从分子及细胞水平的改变研究经口摄入的Cr（Ⅵ）对小鼠的毒性效应
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摘要
铬是自然界中广泛存在的一种元素，主要以三价铬(Cr(Ⅲ))和六价铬(Cr(Ⅵ))的形式存在。受环境中物理、化学和生物等因素的影响，Cr(Ⅲ)与Cr(Ⅵ)之间可以相互转化，但两者对人类健康有着截然不同的影响。Cr(Ⅲ)是一种人体必需的微量元素，它是葡萄糖耐量因子的组成部分，对调节糖代谢、维持体内正常的耐量起重要作用。而Cr(Ⅵ)则被列为对人体危害最大的化学物质之一，也是国际公认的重金属致癌物。
随着铬化合物在工业上的广泛使用，这些生产工业排放的废水、废气和废渣造成的铬污染问题已受到全世界的普遍关注。散布在环境中的Cr(Ⅵ)以离子状态随水循环，它不能被微生物分解，但可被动植物吸收向人体转移，并沿食物链出现生物放大效应，进而影响整个生态系统的平衡，危害人类健康。Cr(Ⅵ)可通过皮肤接触、呼吸吸入和经口摄入三种方式进入人体。其中，皮肤接触和呼吸吸入是职业人群接触Cr(Ⅵ)的主要途径。研究证实，长期暴露于Cr(Ⅵ)环境中的作业工人易患过敏性皮炎和湿疹，还能出现鼻粘膜穿孔或溃疡，慢性鼻炎和支气管炎，甚至导致肺气肿，从而影响肺功能。呼吸吸入的Cr(Ⅵ)对人体造成的最严重的危害在于增加了罹患呼吸道肿瘤的危险性。经口摄入包括饮水和摄入食物，是非职业人群接触Cr(Ⅵ)的最主要方式，国内外学者先后报道了多起因食入Cr(Ⅵ)污染的食物影响人群健康的事件。
大量体外实验证实Cr(Ⅵ)对多种细胞均具有毒性效应，包括肝细胞、肾细胞、成纤维细胞以及淋巴细胞等。此外，皮下注射和腹腔内注射Cr(Ⅵ)的动物实验研究也证实Cr(Ⅵ)能引起机体多个脏器的损伤，其中以肝脏和肾脏的损伤较为明显。但是，由于Cr(Ⅵ)特殊的致毒机制，以皮下注射和腹腔内注射方式建立的动物模型实验并不能正确反映经口摄入的Cr(Ⅵ)对机体产生的毒性效应。而在为数不多的以灌胃或自由饮水方式摄入Cr(Ⅵ)的动物实验中，对Cr(Ⅵ)引起机体毒性效应的研究至今未有定论。
为进一步阐明经口摄入的Cr(Ⅵ)在体内的毒性效应，有必要从分子和细胞水平上研究其在体内可能的致毒机理。综合对Cr(Ⅵ)的一系列体外和体内的研究可以得出，Cr(Ⅵ)引起毒性的最为重要的一个方面就是大量活性活性氧(ROS)的生成并由此引起的氧化应激。近年来，大量研究表明，ROS与细胞凋亡存在着十分密切的关系，它可通过多个信号途径干扰正常的细胞凋亡。因此，通过研究Cr(Ⅵ)对细胞凋亡的诱导有可能阐明Cr(Ⅵ)在体内的致毒机理。
本研究对受试动物以灌胃方式给予Cr(Ⅵ)，通过比较其对不同组织器官造成的损伤，进一步研究经口摄入的Cr(Ⅵ)在体内引起的毒性效应；同时，通过研究Cr(Ⅵ)对细胞凋亡的诱导，以凋亡重要相关蛋白的改变为研究中心探讨其在体内的毒作用机理。
按实验设计，将健康雄性ICR小鼠随机分为4组，每组均为10只；对照组用蒸馏水灌胃，处理组以K_2Cr_2O_7溶液灌胃，剂量设计分别为25、50、100mg/kg体重，灌胃量以小鼠体重计为0.1mL/10g体重。每天灌胃1次，分别给予灌胃1d或5d。染毒结束后继续饲养24h，处死前对小鼠进行摘眼球取血，并立即分离血淋巴细胞进行彗星实验。处死小鼠后迅速切取部分新鲜肝脏和肾脏组织，用于电镜实验和TUNEL实验；剩余组织用液氮速冻后用Western blot进行p53、Bcl-2、Bax、细胞色素c蛋白水平测定以及caspase-3酶活化水平测定，并进行ROS水平、脂质过氧化产物丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性的检测。
实验结果如下：
1．K_2Cr_2O_7染毒小鼠外周血淋巴细胞彗星实验结果显示，1d或5d染毒后随剂量的增加各染毒组尾长也随之升高，并具有显著性差异；除5d染毒的最低剂量组外，其余两个时间段的各染毒组尾相均显著高于对照组；但5d染毒与1d染毒的尾长及尾相数值相比，升高趋势有所降低。
2．K_2Cr_2O_7染毒1d或5d后小鼠肝脏ROS水平均高于对照组，并且，除1d染毒的最低剂量组外，其余各剂量组与对照组比均具有显著性差异。
3．小鼠经K_2Cr_2O_7染毒1d后最低剂量组肝脏SOD活性稍高于对照组，但并无显著性差异，其余两个剂量组SOD活性与对照组相比均无明显变化；5d染毒后各剂量组的SOD活性均显著低于对照组。
4．K_2Cr_2O_7染毒小鼠肝脏CAT活性除1d和5d染毒的最低剂量组与对照组无明显差异外其余各组均低于对照组且具有显著性差异。
5．小鼠经K_2Cr_2O_7染毒1d或5d后，随剂量的升高肝脏MDA含量有上升趋势，但与对照组相比未见统计学差异。
6．经K_2Cr_2O_7染毒1d或5d后，各剂量组小鼠肾脏ROS、MDA、SOD和CAT与对照组相比均没有显著性差异。
7．透射电镜显示，与对照相比，经K_2Cr_2O_7染毒1d或5d后小鼠肝脏细胞超微结构均出现凋亡特征性改变：细胞核皱缩，染色质浓缩并发生边聚化；线粒体变的致密，嵴消失，并且线粒体发生空泡化改变。
8．本研究用TUNEL实验检测K_2Cr_2O_7染毒后小鼠肝脏细胞DNA降解情况，结果所示：与对照组相比，K_2Cr_2O_7染毒1d后小鼠肝细胞核呈棕色的细胞即凋亡细胞数明显增多；5d染毒小鼠肝细胞内也发生相似改变。在1d和5d的两个染毒时间段，随剂量的升高调亡率也随之上升，并显著高于对照组，呈现出明显的剂量反应关系。
9．小鼠经0、25、50、100mg/kg K_2Cr_2O_7染毒1d或5d后，肝组织细胞内caspase-3酶原裂解产生的caspase-3活性片段(17kD)蛋白条带逐渐变粗。与对照组相比，随染毒剂量的增加，caspase-3酶活化逐渐增加，并在最高剂量组100mg/kg差异具有显著性。
10．小鼠染毒后肝组织细胞内p53蛋白水平情况显示，与对照组相比，1d或5d染毒的各剂量组小鼠肝组织细胞内p53蛋白水平均有升高，并在最高剂量组100mg/kg时差异具有显著性。
11．经K_2Cr_2O_7染毒1d或5d后小鼠肝组织细胞内Bcl-2蛋白水平随染毒剂量的增加均呈下降趋势，并且，1d染毒的100mg/kg以及5d染毒的50mg/kg和100mg/kg剂量组均显著低于对照组。Bax蛋白水平随染毒剂量的增加均有升高，但仅在5d染毒的100mg/kg剂量组蛋白水平显著高于对照组。
12．1d或5d染毒小鼠肝组织细胞胞浆内细胞色素c蛋白水平随染毒剂量的增加均呈升高趋势，并且，1d染毒的50mg/kg和100mg/kg剂量组以及5d染毒的100mg/kg剂量组均显著高于对照组。
主要结论：
1．Cr(Ⅵ)灌胃引起小鼠肝脏ROS的显著升高，同时抗氧化酶SOD和CAT活性也明显降低，表明经口摄入的Cr(Ⅵ)破坏体内抗氧化系统的平衡并使机体处于氧化应激状态是Cr(Ⅵ)引起毒性效应的一个重要原因。
2．与肝脏相比，本研究未发现Cr(Ⅵ)灌胃后小鼠肾脏出现明显的氧化应激，表明经口摄入的Cr(Ⅵ)经过体内氧化还原代谢后对机体各个组织器官造成的毒性效应会有较大差异。
3．Cr(Ⅵ)染毒后，小鼠淋巴细胞DNA出现损伤，表明经口摄入的Cr(Ⅵ)在体内产生的ROS和/或还原过程中产生的低价态Cr所引起的DNA损伤是Cr(Ⅵ)的毒性作用之一。
4．Cr(Ⅵ)染毒导致肝细胞发生凋亡，同时肝脏组织中凋亡相关蛋白p53、Bcl-2、Bax、细胞色素c蛋白水平以及caspase-3酶活化水平也发生明显改变，表明p53、Bcl-2、Bax、细胞色素c以及caspase-3参与了Cr(Ⅵ)诱导的细胞凋亡。该结果提示：Cr(Ⅵ)引起机体毒性效应的一个重要原因很有可能就是干扰了机体正常的细胞凋亡过程。
Chromium is an ubiquitous element in nature that exists in primarily two valences states, trivalent (Cr(III)) and hexavalent (Cr(VI)). The two valence states can be transformed mutually under the influence of physical, chemical and biological factors in the environment. However, the effects of the two states on human health are quite different. Cr(III) is an essential micronutrient for human. It is a part of the glucose tolerance factor, which plays an important role in regulating glucose metabolism for the maintenance of normal glucose levels. In contrast, Cr(VI) is regarded as one of the most toxic chemical substances, as well as an international recognized heavy metal carcinogen.
With wide use of the chromium compounds in industries, the waste water, exhaust gas and waste residue emitted from these industries resulted in severe chromium pollution. Great attention has been payed to this increasing severe pollution by the world. Cr(VI) scattered in the environment cycles with the water in ion state. It can not be decomposed by microorganism, but can be absorbed by animals and plants
and then affect the balance of the whole ecosystem. Cr(VI) is toxic to humans due to the effect of biological amplification of Cr(VI) along food chain. Cr(VI) may enter into the human body via dermal contact, inhalation and ingestion. Dermal contact and inhalation are the two major routes of occupational Cr(VI) exposure. Studies have demonstrated that the workers exposed to Cr(VI) chronically were vulnerable to dermatitis and eczema, as well as perforation, ulcer, chronic rhinitis and bronchitis. Cr(VI) may also result in emphysema, and consequently affect lung function. The most toxic effect on humans via inhalation is that it increases the risk of suffering from respiratory tract cancer. Water and food intake is a common route of Cr(VI) exposure for nonoccupational people. Several cases about which ingestion of food contaminated by Cr(VI) caused adverse effects on humans have been reported by researchers at home and abroad.
A plenty of in vitro experiments have demonstrated that Cr(VI) could induce toxic effects on many types of cells including hepatocytes, renal cells, fibroblasts and lymphocytes. Animal experiments also confirmed that Cr(VI) exposed by subcutaneous or intraperitoneal injection could cause several organs damage, especially for liver and kidney. However, due to the special toxic mechanisms of Cr(VI), animal experiments established by subcutaneous or intraperitoneal injection could not properly reflected the toxicity induced by oral administration of Cr(VI) in vivo. Up to now, only a few animal experiments administrated with Cr(VI) by gavage or drinking at liberty have been reported, moreover, conclusions on toxicity induced by oral administration of Cr(VI) remains uncertain.
To illustrate the toxicity of Cr(VI) exposed by oral administration in vivo, it is necessary to study the potential toxic mechanisms at molecular and cellular level. Overview on a series of in vitro and in vivo researches, it can be concluded that an important aspect of Cr(VI) toxicity is the formation of plentiful reactive oxygen
species (ROS) and the consequent oxidative stress. Recently, a large number of studies have showed a close relationship between ROS and apoptosis because ROS could disturb normal apoptosis through many cell signaling pathways. Therefore, investigating the apoptosis induced by Cr(VI) may contribute to illustrating the toxic mechanisms of Cr(VI) in vivo.
The present study was designed to give Cr(VI) to the experimental animals via oral administration (gavage). It was planed to study the toxic effects of Cr(VI) in vivo by comparing the damage in different organs. Furthermore, evaluating the changes of apoptotic related proteins in the process of cell apoptosis was also planed to investigate the toxic mechanisms of Cr(VI) in vivo.
According to the experimental design, the animals were randomly distributed into four groups and were orally administrated (gavage) with potassium dichromate (K_2Cr_2O_7) at a dose of 0, 25, 50, 100 mg/kg body weight once daily for 1 day or consecutive 5 days. The mice were continued breeding for 24 h after the last Cr(VI) treatment. The blood was collected by extirpating the eyeballs, and the blood lymphocytes were separated out for comet assay immediately. The tissues of liver and kidney were quickly dissected off after the mice were sacrificed. One part of the tissues were used for TUNEL assay and transmission electron microscope, the remains were frozen in liquid nitrogen for p53, Bcl-2, Bax, cytochrome c protein level and caspase-3 activation determined by Western blot, and also for ROS level, malondialdehyde (MDA) content, superoxide dismutase (SOD) activity and catalase (CAT) activity evaluation.
Main results:
1. The comet assay of peripheral blood lymphocytes showed that the tail length in treatment groups significantly increased in a dose-dependent manner after 1 day or 5
days of K_2Cr_2O_7 exposure. Except for the lowest dose group at 1 day of exposure, the tail moment at the other treatment groups were obviously higher than that of the control groups. However, comparing with 1 day of exposure, the increasing tendency of the value on the tail length and the tail moment declined after the mice exposed to K_2Cr_2O_7 for 5 days.
2. After the mice were exposed to K_2Cr_2O_7 for 1 day or 5 days, ROS levels in mice liver in treatment groups were all higher than those in control groups. Except for the lowest dose group at 1 day of exposure, there was a significant difference between the control group and the other treatment groups.
3. SOD activity in mice liver was not modified by the administration of K_2Cr_2O_7 at 50 and 100 mg/kg dose for 1 day. However, the value showed a non-significant increase at 25 mg/kg dose compared with the controls. SOD activity declined significantly at the three doses after 5 days of exposure as compared to the controls.
4. CAT activity in mice liver showed a dose-dependent decrease in all K_2Cr_2O_7 treated groups and the difference was significant at 50 and 100 mg/kg doses as compared to the controls.
5. The MDA content in mice liver increased in a dose-dependent manner after administration of K_2Cr_2O_7 to mice for 1 day or 5 days, but no statistical differences were observed between the control and treatment groups.
6. No significant changes were observed on ROS, MDA, SOD and CAT in kidney after administration of K_2Cr_2O_7 to mice between the control and treatment groups.
7. Transmission electron microscopy revealed the ultrastructural alterations of hepatocytes undergoing apoptosis in mouse liver treated with K_2Cr_2O_7 for 1 and 5 days. The typical apoptosis alterations were described as follows: the nucleus of mouse hepatocytes become shrunken. The chromatin was condensed to form dense compact masses and arranged along the crinkly nuclear membrane. In addition, the
mitochondria became a compact and vacuolar structure with loss of cristae.
8. TUNEL assay was used to evaluate DNA degradation in liver after the mice were treated with K_2Cr_2O_7 . The number of cells stained with brown significantly increased in K_2Cr_2O_7 -treated mice compared with the control animals after 1 day of exposure. Such phenomenon also occurred in liver cells after administration of K_2Cr_2O_7 for 5 days. Dose- and time-dependent increase was observed after 1 and 5 days of K_2Cr_2O_7 exposure to mice and the increase was significant between the control and treatment groups.
9. After the mice were exposed to K_2Cr_2O_7 at 0, 25, 50, 100 mg/kg doses for 1 day or 5 days, it could be seen that the protein band of caspase-3 active segment (17 kD) hydrolyzed from caspase-3 zymogen in liver cells gradually became thick. Caspase-3 activation enhanced in accordance with the increase of K_2Cr_2O_7 , and the difference compared with the control animals was significant at the dose of 100 mg/kg.
10. p53 protein level in liver showed that the administration of K_2Cr_2O_7 to mice for 1 or 5 days enhanced the p53 protein level, and the difference compared with the control animals was significant at the dose of 100 mg/kg.
11. Bcl-2 protein level in liver showed a declining tendency with the increase of K_2Cr_2O_7 at 1 or 5 days. Furthermore, the Bcl-2 protein level at 100 mg/kg dose for 1 day as well as at 50 mg/kg and 100 mg/kg doses for 5 days decreased significantly compared with the control groups. Bax protein level increased in a dose-dependent manner, and the difference was significant only at 100 mg/kg dose for 5 days.
12. Cytochrome c protein level in hepatocytes cytoplasm enhanced in accordance with the increase of K_2Cr_2O_7 after 1 day or 5 days of exposure, and the values at 50 mg/kg and 100 mg/kg doses for 1 day as well as at 100 mg/kg dose for 5 days showed a statistical significance compared with the controls.
Main conclusions:
1. ROS level increased and SOD and CAT activity decreased in mice liver after the animals were exposed with oral administration of Cr(VI). The results indicated that one important reason for the toxicity induced by Cr(VI) is that Cr(VI) exposed by oral administration could destroy the balance of antioxidative system and cause the following oxidative stress in vivo.
2. Compared with liver, no significant oxidative stress was observed in kidney after oral administration of Cr(VI) to mice, indicating that the toxic effects on different organs may be different after Cr(VI) underwent redox metabolism in vivo.
3. Oral administration of Cr(VI) induced DNA damage in mice lymphocytes, indicating that the DNA damage induced by ROS and/or Cr intermediates which formed in the Cr(VI) metabolism was one of the Cr(VI) toxic effects.
4. Cr(VI) could induce hepatocytes apoptosis and alter the p53, Bcle-2, Bax, cytochrome c protein levels and caspase-3 activation, indicating p53, Bcle-2, Bax, cytochrome c and caspase-3 take part in the cell apoptosis induced by Cr(VI). These results suggests that an important mechanism on the Cr(VI) toxicity is to disturbe the normal process of cell apoptosis.
随着铬化合物在工业上的广泛使用，这些生产工业排放的废水、废气和废渣造成的铬污染问题已受到全世界的普遍关注。散布在环境中的Cr(Ⅵ)以离子状态随水循环，它不能被微生物分解，但可被动植物吸收向人体转移，并沿食物链出现生物放大效应，进而影响整个生态系统的平衡，危害人类健康。Cr(Ⅵ)可通过皮肤接触、呼吸吸入和经口摄入三种方式进入人体。其中，皮肤接触和呼吸吸入是职业人群接触Cr(Ⅵ)的主要途径。研究证实，长期暴露于Cr(Ⅵ)环境中的作业工人易患过敏性皮炎和湿疹，还能出现鼻粘膜穿孔或溃疡，慢性鼻炎和支气管炎，甚至导致肺气肿，从而影响肺功能。呼吸吸入的Cr(Ⅵ)对人体造成的最严重的危害在于增加了罹患呼吸道肿瘤的危险性。经口摄入包括饮水和摄入食物，是非职业人群接触Cr(Ⅵ)的最主要方式，国内外学者先后报道了多起因食入Cr(Ⅵ)污染的食物影响人群健康的事件。
大量体外实验证实Cr(Ⅵ)对多种细胞均具有毒性效应，包括肝细胞、肾细胞、成纤维细胞以及淋巴细胞等。此外，皮下注射和腹腔内注射Cr(Ⅵ)的动物实验研究也证实Cr(Ⅵ)能引起机体多个脏器的损伤，其中以肝脏和肾脏的损伤较为明显。但是，由于Cr(Ⅵ)特殊的致毒机制，以皮下注射和腹腔内注射方式建立的动物模型实验并不能正确反映经口摄入的Cr(Ⅵ)对机体产生的毒性效应。而在为数不多的以灌胃或自由饮水方式摄入Cr(Ⅵ)的动物实验中，对Cr(Ⅵ)引起机体毒性效应的研究至今未有定论。
为进一步阐明经口摄入的Cr(Ⅵ)在体内的毒性效应，有必要从分子和细胞水平上研究其在体内可能的致毒机理。综合对Cr(Ⅵ)的一系列体外和体内的研究可以得出，Cr(Ⅵ)引起毒性的最为重要的一个方面就是大量活性活性氧(ROS)的生成并由此引起的氧化应激。近年来，大量研究表明，ROS与细胞凋亡存在着十分密切的关系，它可通过多个信号途径干扰正常的细胞凋亡。因此，通过研究Cr(Ⅵ)对细胞凋亡的诱导有可能阐明Cr(Ⅵ)在体内的致毒机理。
本研究对受试动物以灌胃方式给予Cr(Ⅵ)，通过比较其对不同组织器官造成的损伤，进一步研究经口摄入的Cr(Ⅵ)在体内引起的毒性效应；同时，通过研究Cr(Ⅵ)对细胞凋亡的诱导，以凋亡重要相关蛋白的改变为研究中心探讨其在体内的毒作用机理。
按实验设计，将健康雄性ICR小鼠随机分为4组，每组均为10只；对照组用蒸馏水灌胃，处理组以K_2Cr_2O_7溶液灌胃，剂量设计分别为25、50、100mg/kg体重，灌胃量以小鼠体重计为0.1mL/10g体重。每天灌胃1次，分别给予灌胃1d或5d。染毒结束后继续饲养24h，处死前对小鼠进行摘眼球取血，并立即分离血淋巴细胞进行彗星实验。处死小鼠后迅速切取部分新鲜肝脏和肾脏组织，用于电镜实验和TUNEL实验；剩余组织用液氮速冻后用Western blot进行p53、Bcl-2、Bax、细胞色素c蛋白水平测定以及caspase-3酶活化水平测定，并进行ROS水平、脂质过氧化产物丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性的检测。
实验结果如下：
1．K_2Cr_2O_7染毒小鼠外周血淋巴细胞彗星实验结果显示，1d或5d染毒后随剂量的增加各染毒组尾长也随之升高，并具有显著性差异；除5d染毒的最低剂量组外，其余两个时间段的各染毒组尾相均显著高于对照组；但5d染毒与1d染毒的尾长及尾相数值相比，升高趋势有所降低。
2．K_2Cr_2O_7染毒1d或5d后小鼠肝脏ROS水平均高于对照组，并且，除1d染毒的最低剂量组外，其余各剂量组与对照组比均具有显著性差异。
3．小鼠经K_2Cr_2O_7染毒1d后最低剂量组肝脏SOD活性稍高于对照组，但并无显著性差异，其余两个剂量组SOD活性与对照组相比均无明显变化；5d染毒后各剂量组的SOD活性均显著低于对照组。
4．K_2Cr_2O_7染毒小鼠肝脏CAT活性除1d和5d染毒的最低剂量组与对照组无明显差异外其余各组均低于对照组且具有显著性差异。
5．小鼠经K_2Cr_2O_7染毒1d或5d后，随剂量的升高肝脏MDA含量有上升趋势，但与对照组相比未见统计学差异。
6．经K_2Cr_2O_7染毒1d或5d后，各剂量组小鼠肾脏ROS、MDA、SOD和CAT与对照组相比均没有显著性差异。
7．透射电镜显示，与对照相比，经K_2Cr_2O_7染毒1d或5d后小鼠肝脏细胞超微结构均出现凋亡特征性改变：细胞核皱缩，染色质浓缩并发生边聚化；线粒体变的致密，嵴消失，并且线粒体发生空泡化改变。
8．本研究用TUNEL实验检测K_2Cr_2O_7染毒后小鼠肝脏细胞DNA降解情况，结果所示：与对照组相比，K_2Cr_2O_7染毒1d后小鼠肝细胞核呈棕色的细胞即凋亡细胞数明显增多；5d染毒小鼠肝细胞内也发生相似改变。在1d和5d的两个染毒时间段，随剂量的升高调亡率也随之上升，并显著高于对照组，呈现出明显的剂量反应关系。
9．小鼠经0、25、50、100mg/kg K_2Cr_2O_7染毒1d或5d后，肝组织细胞内caspase-3酶原裂解产生的caspase-3活性片段(17kD)蛋白条带逐渐变粗。与对照组相比，随染毒剂量的增加，caspase-3酶活化逐渐增加，并在最高剂量组100mg/kg差异具有显著性。
10．小鼠染毒后肝组织细胞内p53蛋白水平情况显示，与对照组相比，1d或5d染毒的各剂量组小鼠肝组织细胞内p53蛋白水平均有升高，并在最高剂量组100mg/kg时差异具有显著性。
11．经K_2Cr_2O_7染毒1d或5d后小鼠肝组织细胞内Bcl-2蛋白水平随染毒剂量的增加均呈下降趋势，并且，1d染毒的100mg/kg以及5d染毒的50mg/kg和100mg/kg剂量组均显著低于对照组。Bax蛋白水平随染毒剂量的增加均有升高，但仅在5d染毒的100mg/kg剂量组蛋白水平显著高于对照组。
12．1d或5d染毒小鼠肝组织细胞胞浆内细胞色素c蛋白水平随染毒剂量的增加均呈升高趋势，并且，1d染毒的50mg/kg和100mg/kg剂量组以及5d染毒的100mg/kg剂量组均显著高于对照组。
主要结论：
1．Cr(Ⅵ)灌胃引起小鼠肝脏ROS的显著升高，同时抗氧化酶SOD和CAT活性也明显降低，表明经口摄入的Cr(Ⅵ)破坏体内抗氧化系统的平衡并使机体处于氧化应激状态是Cr(Ⅵ)引起毒性效应的一个重要原因。
2．与肝脏相比，本研究未发现Cr(Ⅵ)灌胃后小鼠肾脏出现明显的氧化应激，表明经口摄入的Cr(Ⅵ)经过体内氧化还原代谢后对机体各个组织器官造成的毒性效应会有较大差异。
3．Cr(Ⅵ)染毒后，小鼠淋巴细胞DNA出现损伤，表明经口摄入的Cr(Ⅵ)在体内产生的ROS和/或还原过程中产生的低价态Cr所引起的DNA损伤是Cr(Ⅵ)的毒性作用之一。
4．Cr(Ⅵ)染毒导致肝细胞发生凋亡，同时肝脏组织中凋亡相关蛋白p53、Bcl-2、Bax、细胞色素c蛋白水平以及caspase-3酶活化水平也发生明显改变，表明p53、Bcl-2、Bax、细胞色素c以及caspase-3参与了Cr(Ⅵ)诱导的细胞凋亡。该结果提示：Cr(Ⅵ)引起机体毒性效应的一个重要原因很有可能就是干扰了机体正常的细胞凋亡过程。
Chromium is an ubiquitous element in nature that exists in primarily two valences states, trivalent (Cr(III)) and hexavalent (Cr(VI)). The two valence states can be transformed mutually under the influence of physical, chemical and biological factors in the environment. However, the effects of the two states on human health are quite different. Cr(III) is an essential micronutrient for human. It is a part of the glucose tolerance factor, which plays an important role in regulating glucose metabolism for the maintenance of normal glucose levels. In contrast, Cr(VI) is regarded as one of the most toxic chemical substances, as well as an international recognized heavy metal carcinogen.
With wide use of the chromium compounds in industries, the waste water, exhaust gas and waste residue emitted from these industries resulted in severe chromium pollution. Great attention has been payed to this increasing severe pollution by the world. Cr(VI) scattered in the environment cycles with the water in ion state. It can not be decomposed by microorganism, but can be absorbed by animals and plants
and then affect the balance of the whole ecosystem. Cr(VI) is toxic to humans due to the effect of biological amplification of Cr(VI) along food chain. Cr(VI) may enter into the human body via dermal contact, inhalation and ingestion. Dermal contact and inhalation are the two major routes of occupational Cr(VI) exposure. Studies have demonstrated that the workers exposed to Cr(VI) chronically were vulnerable to dermatitis and eczema, as well as perforation, ulcer, chronic rhinitis and bronchitis. Cr(VI) may also result in emphysema, and consequently affect lung function. The most toxic effect on humans via inhalation is that it increases the risk of suffering from respiratory tract cancer. Water and food intake is a common route of Cr(VI) exposure for nonoccupational people. Several cases about which ingestion of food contaminated by Cr(VI) caused adverse effects on humans have been reported by researchers at home and abroad.
A plenty of in vitro experiments have demonstrated that Cr(VI) could induce toxic effects on many types of cells including hepatocytes, renal cells, fibroblasts and lymphocytes. Animal experiments also confirmed that Cr(VI) exposed by subcutaneous or intraperitoneal injection could cause several organs damage, especially for liver and kidney. However, due to the special toxic mechanisms of Cr(VI), animal experiments established by subcutaneous or intraperitoneal injection could not properly reflected the toxicity induced by oral administration of Cr(VI) in vivo. Up to now, only a few animal experiments administrated with Cr(VI) by gavage or drinking at liberty have been reported, moreover, conclusions on toxicity induced by oral administration of Cr(VI) remains uncertain.
To illustrate the toxicity of Cr(VI) exposed by oral administration in vivo, it is necessary to study the potential toxic mechanisms at molecular and cellular level. Overview on a series of in vitro and in vivo researches, it can be concluded that an important aspect of Cr(VI) toxicity is the formation of plentiful reactive oxygen
species (ROS) and the consequent oxidative stress. Recently, a large number of studies have showed a close relationship between ROS and apoptosis because ROS could disturb normal apoptosis through many cell signaling pathways. Therefore, investigating the apoptosis induced by Cr(VI) may contribute to illustrating the toxic mechanisms of Cr(VI) in vivo.
The present study was designed to give Cr(VI) to the experimental animals via oral administration (gavage). It was planed to study the toxic effects of Cr(VI) in vivo by comparing the damage in different organs. Furthermore, evaluating the changes of apoptotic related proteins in the process of cell apoptosis was also planed to investigate the toxic mechanisms of Cr(VI) in vivo.
According to the experimental design, the animals were randomly distributed into four groups and were orally administrated (gavage) with potassium dichromate (K_2Cr_2O_7) at a dose of 0, 25, 50, 100 mg/kg body weight once daily for 1 day or consecutive 5 days. The mice were continued breeding for 24 h after the last Cr(VI) treatment. The blood was collected by extirpating the eyeballs, and the blood lymphocytes were separated out for comet assay immediately. The tissues of liver and kidney were quickly dissected off after the mice were sacrificed. One part of the tissues were used for TUNEL assay and transmission electron microscope, the remains were frozen in liquid nitrogen for p53, Bcl-2, Bax, cytochrome c protein level and caspase-3 activation determined by Western blot, and also for ROS level, malondialdehyde (MDA) content, superoxide dismutase (SOD) activity and catalase (CAT) activity evaluation.
Main results:
1. The comet assay of peripheral blood lymphocytes showed that the tail length in treatment groups significantly increased in a dose-dependent manner after 1 day or 5
days of K_2Cr_2O_7 exposure. Except for the lowest dose group at 1 day of exposure, the tail moment at the other treatment groups were obviously higher than that of the control groups. However, comparing with 1 day of exposure, the increasing tendency of the value on the tail length and the tail moment declined after the mice exposed to K_2Cr_2O_7 for 5 days.
2. After the mice were exposed to K_2Cr_2O_7 for 1 day or 5 days, ROS levels in mice liver in treatment groups were all higher than those in control groups. Except for the lowest dose group at 1 day of exposure, there was a significant difference between the control group and the other treatment groups.
3. SOD activity in mice liver was not modified by the administration of K_2Cr_2O_7 at 50 and 100 mg/kg dose for 1 day. However, the value showed a non-significant increase at 25 mg/kg dose compared with the controls. SOD activity declined significantly at the three doses after 5 days of exposure as compared to the controls.
4. CAT activity in mice liver showed a dose-dependent decrease in all K_2Cr_2O_7 treated groups and the difference was significant at 50 and 100 mg/kg doses as compared to the controls.
5. The MDA content in mice liver increased in a dose-dependent manner after administration of K_2Cr_2O_7 to mice for 1 day or 5 days, but no statistical differences were observed between the control and treatment groups.
6. No significant changes were observed on ROS, MDA, SOD and CAT in kidney after administration of K_2Cr_2O_7 to mice between the control and treatment groups.
7. Transmission electron microscopy revealed the ultrastructural alterations of hepatocytes undergoing apoptosis in mouse liver treated with K_2Cr_2O_7 for 1 and 5 days. The typical apoptosis alterations were described as follows: the nucleus of mouse hepatocytes become shrunken. The chromatin was condensed to form dense compact masses and arranged along the crinkly nuclear membrane. In addition, the
mitochondria became a compact and vacuolar structure with loss of cristae.
8. TUNEL assay was used to evaluate DNA degradation in liver after the mice were treated with K_2Cr_2O_7 . The number of cells stained with brown significantly increased in K_2Cr_2O_7 -treated mice compared with the control animals after 1 day of exposure. Such phenomenon also occurred in liver cells after administration of K_2Cr_2O_7 for 5 days. Dose- and time-dependent increase was observed after 1 and 5 days of K_2Cr_2O_7 exposure to mice and the increase was significant between the control and treatment groups.
9. After the mice were exposed to K_2Cr_2O_7 at 0, 25, 50, 100 mg/kg doses for 1 day or 5 days, it could be seen that the protein band of caspase-3 active segment (17 kD) hydrolyzed from caspase-3 zymogen in liver cells gradually became thick. Caspase-3 activation enhanced in accordance with the increase of K_2Cr_2O_7 , and the difference compared with the control animals was significant at the dose of 100 mg/kg.
10. p53 protein level in liver showed that the administration of K_2Cr_2O_7 to mice for 1 or 5 days enhanced the p53 protein level, and the difference compared with the control animals was significant at the dose of 100 mg/kg.
11. Bcl-2 protein level in liver showed a declining tendency with the increase of K_2Cr_2O_7 at 1 or 5 days. Furthermore, the Bcl-2 protein level at 100 mg/kg dose for 1 day as well as at 50 mg/kg and 100 mg/kg doses for 5 days decreased significantly compared with the control groups. Bax protein level increased in a dose-dependent manner, and the difference was significant only at 100 mg/kg dose for 5 days.
12. Cytochrome c protein level in hepatocytes cytoplasm enhanced in accordance with the increase of K_2Cr_2O_7 after 1 day or 5 days of exposure, and the values at 50 mg/kg and 100 mg/kg doses for 1 day as well as at 100 mg/kg dose for 5 days showed a statistical significance compared with the controls.
Main conclusions:
1. ROS level increased and SOD and CAT activity decreased in mice liver after the animals were exposed with oral administration of Cr(VI). The results indicated that one important reason for the toxicity induced by Cr(VI) is that Cr(VI) exposed by oral administration could destroy the balance of antioxidative system and cause the following oxidative stress in vivo.
2. Compared with liver, no significant oxidative stress was observed in kidney after oral administration of Cr(VI) to mice, indicating that the toxic effects on different organs may be different after Cr(VI) underwent redox metabolism in vivo.
3. Oral administration of Cr(VI) induced DNA damage in mice lymphocytes, indicating that the DNA damage induced by ROS and/or Cr intermediates which formed in the Cr(VI) metabolism was one of the Cr(VI) toxic effects.
4. Cr(VI) could induce hepatocytes apoptosis and alter the p53, Bcle-2, Bax, cytochrome c protein levels and caspase-3 activation, indicating p53, Bcle-2, Bax, cytochrome c and caspase-3 take part in the cell apoptosis induced by Cr(VI). These results suggests that an important mechanism on the Cr(VI) toxicity is to disturbe the normal process of cell apoptosis.
引文
戴帅．2000．一起由铬引起的食物中毒[J]．海峡预防医学杂志，6(5)：37
杜良，王金生．2004．铬渣毒性对环境的影响与产出量分析[J]．安全与环境学报，4(2)；34-37．
金仁哲，李宝贵，玄长龙等．1994．一起六价铬污染饮用水引起中毒的报告[J]．中国国境卫生检疫杂志，17：14．
李梅莉，朗胜喜．2004．某厂铬酸盐对作业工人健康的影响[J]．职业与健康，20(4)：26-27．
梁群超，郭剑英，唐兆新．2006．自由基与细胞凋亡[J]．上海畜牧兽医通讯，4：41—43．
史黎薇．2003．铬化合物对健康影响的研究进展[J]．卫生研究，32(4)：410-412．
王家骏，叶丽杰，孙文娟，等．1998．铬致大鼠肾组织脂质过氧化作用[J]．卫生毒理学杂志，12(4)：261—262．
王筱冰，张小翠，夏妙红，等．2006．Caspase的活化机制[J]．现代生物医学进展，6(3)：53-55．
谢萍．2004．自由基与细胞凋亡[J]．生物学教学，29(1)：3-4．
张洪霞，钟才高，徐顺清，等．2006．Cr(Ⅵ)诱导肝细胞凋亡与氧化损伤、p53和半胱氨酸天冬氨酸蛋白酶3表达的关系[J]．中国药理学与毒理学杂志，20(2)：144-151．
张双华．2005．70％电子垃圾涌入我国污染使村民癌症高发[OL]．人民网-人民日报海外版，2005-8-8，http://www.chinabyte.com/450/2062450.shtml．
赵堃，柴立元，王云燕等．2006．水环境中铬的存在形态及迁移转化规律[J]．工业安全与环保，32(8)：1-3．
褚启龙，杨克敌，王爱国．2003．氧化应激与细胞凋亡关系的研究进展[J]．卫生研究，32(3)：
276—279
Arakawa, H., R. Ahmad, M. Naoui, and H.A. TajmiroRiahi. 2000. A comparative study of calf thymus
DNA binding to Cr(III) and Cr(VI) ions. Evidence for the guanine N-7-chromium-phosphate
chelate formation. J Biol Chem. 275: 10~50-10!53.
Bagchi, D., E.A. Hassoun, M. Bagchi, D.E Muldoon, and S.J. Stchs. !995a. Oxidative stress induced
by chronic administration of sodium dichromate [Cr(~1)] to rats. Comp Biochem Physiol C
Pharmacol Toxicol Endocrinol. 110: 281-287.
Bagchi, D., E.A. Hassoun, M. Bagchi, and S.J. Stohs. 1995b. Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 110: 177-187.
Banin, S., L. Moyal, S. Shieh, Y. Taya, CW. Anderson, L. Chessa, N.I. Smorodinsky, C. Prives, Y. Reiss, Y. Shiloh, and Y. Ziv. 1998. Enhanced phosphorylation of p53 by ATM in response to DNA damage. Science. 281: 1674-1677.
Barros, M.H., L.E. Netto, and A.J. Kowaltowski. 2003. H(2)O(2) generation in Saccharomyces cerevisiae respiratory pet mutants: effect of cytochrome c. Free Radic Biol Med. 35: 179-188.
Beck, M.A. 1999. Selenium and host defence towards viruses. Proc Nutr Soc. 58: 707-711.
Bjorkerud, B.and S. Bjorkerud. 1996. Contrary effects of lightly and strongly oxidized LDL with potent promotion of growth versus apoptosis on arterial smooth muscle cells, macrophages, and fibroblasts. Arterioscler Thromb Vasc Biol. 16: 416-424.
Blankert, S.A., V.H. Coryell, B.T. Picard, K.K. Wolf, R.E. Lomas, and D.M. Stearns. 2003. Characterization of nonmutagenic Cr(III)-DNA interactions. Chem Res Toxicol. 16: 847-854.
Bose, R.N., S. Moghaddas, P.A. Mazzer, L.P. Dudones, L. Joudah, and D. Stroup. 1999. Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation. Nucleic Acids Res. 27: 2219-2226.
Carlisle, D.L., DE. Pritchard, J. Singh, B.M. Owens, L.J. Blankenship, J.M. Orenstein, and S.R. Patierno. 2000. Apoptosis and P53 induction in human lung fibroblasts exposed to chromium (VI): effect of ascorbate and tocopherol. Toxicol Sci. 55: 60-68.
Casadevall, M., P. da Cruz Fresco, and A. Kortenkamp. 1999. Chromium(VI)-mediated DNA damage: oxidative pathways resulting in the formation of DNA breaks and abasic sites. Chem Biol Interact. 123: 117-132.
Celander, D.W.and T.R. Cech. 1990. Iron(II)-ethylenediaminetetraacetic acid catalyzed cleavage of RNA and DNA oligonucleotides: similar reactivity toward single- and double-stranded forms. Biochemistry. 29: 1355-1361.
Coogan, T.P., J. Motz, C.A. Snyder, K.S. Squibb, and M. Costa. 1991. Differential DNA-protein crosslinking in lymphocytes and liver following chronic drinking water exposure of rats to potassium chromate. Toxicol Appl Pharmacol. 109: 60-72.
Costa, M. 2003. Potential hazards of hexavalent chromate in our drinking water. Toxicol Appl Pharmacol. 188: 1-5.
Crump, C, K. Crump, E. Hack, R. Luippold, K. Mundt, E. Liebig, J. Panko, D. Paustenbach, and D. Proctor. 2003. Dose-response and risk assessment of airborne hexavalent chromium and lung cancer mortality. Risk Anal. 23: 1147-1163.
D'Agostini, F, A. Izzotti, C. Bennicelli, A. Camoirano, E. Tampa, and S. De Flora. 2002. Induction of apoptosis in the lung but not in the liver of rats receiving intra-tracheal instillations of chromium(VI). Carcinogenesis. 23: 587-593.
Dana Devi, K., R. Rozati, B. Saleha Banu, K. Jamil, and P. Grover. 2001. In vivo genotoxic effect of potassjum dichromate in mice leukocytes using comet assay. Food Chem Toxicol. 39: 859-865.
Dartsch, PC, S. Hildenbrand, R. Kimmel, and F.W. Schmahl. 1998. Investigations on the nephrotoxicity and hepatotoxicity of trivalent and hexavalent chromium compounds. Int Arch Occup Environ Health. 71 Suppl: S40-45.
das Neves, R.P., T.M. Santos, L. Pereira Mde, and J.P. de Jesus. 2002. Comparative histological studies on liver of mice exposed to Cr(VI) and Cr(V) compounds. Hum Exp Toxicol. 21: 365-369.
De Flora, S. 2000. Threshold mechanisms and site specificity in chromium(Vl) carcinogenesis. Carcinogenesis. 21: 533-541.
De Flora, S., GS. Badolati, D. Serra, A. Picciotto, M.R. Magnolia, and V. Savarino. 1987. Circadian reduction of chromium in the gastric environment. Mutat Res. 192: 169-174.
De Flora, S., A. Camoirano, M. Bagnasco, C. Bennicelli, G.E. Corbett, and B.D. Kerger. 1997. Estimates of the chromium(VI) reducing capacity in human body compartments as a mechanism for attenuating its potential toxicity and carcinogenicity. Carcinogenesis. 18: 531-537.
De Flora, S., D. Serra, A. Camoirano, and P. Zanacchi. 1989. Metabolic reduction of chromium, as related to its carcinogenic properties. Biol Trace Elem Res. 21: 179-187.
Ding, M.and X. Shi. 2002. Molecular mechanisms of Cr(VI)-induced carcinogenesis. Mol Cell Biochem. 234-235: 293-300.
Edremitlioglu, M., D. Kilic, S. Oter, U. Kisa, A. Korkmaz, O. Coskun, and O. Bedir. 2005. The effect of hyperbaric oxygen treatment on the renal functions in septic rats: relation to oxidative damage. Surg Today. 35:653-661.
Fan, T.J., L.H. Han, R.S. Cong, and J. Liang. 2005. Caspase family proteases and apoptosis. Acta Biochim Biophys Sin (Shanghai). 37: 719-727.
Febel, H., B. Szegedi, and S. Huszar. 2001. Absorption of inorganic, trivalent and hexavalent chromium following oral and intrajejunal doses in rats. Acta Vet Hung. 49: 203-209.
Feng, Z., W. Hu, W.N. Rom, M. Costa, and M.S. Tang. 2003. Chromium(VI) exposure enhances polycyclic aromatic hydrocarbon-DNA binding at the p53 gene in human lung cells. Carcinogenesis. 24: 771-778.
Finkel, T. 2003. Oxidant signals and oxidative stress. Curr Opin Cell Biol. 15: 247-254.
Fornace, A.J., Jr., D.S. Seres, J.F. Lechner, and C.C. Harris. 1981. DNA-protein cross-linking by chromium salts. Chem Biol Interact. 36: 345-354.
Fridman, J.S.and S.W. Lowe. 2003. Control of apoptosis by p53. Oncogene. 22: 9030-9040.
Gambelunghe, A., R. Piccinini, G Abbritti, M. Ambrogi, B. Ugolini, C. Marchetti, G Migliorati, C. Balducci, and G. Muzi. 2006. Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4). J Occup Environ Med. 48:319-325.
Goulart, M., M.C. Batoreu, A.S. Rodrigues, A. Laires, and J. Rueff. 2005. Liponeroxidation products and thiol antioxidants in chromium exposed workers. Mutagenesis. 20: 311-315.
Gunaratnam, M.and M.H. Grant. 2002. Chromium(VI)-inducerl damage to the cytoskeleton and cell death in isolated hepatocytes. Biochem Soc Trans. 30: 748-750.
Hayashi, Y., T. Kondo, Q.L. Zhao, R. Ogawa, Z.G. Cui, L.B. Feril, Jr., H. Teranishi, and M. Kasuya. 2004. Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells. Toxicol Appl Pharmacol. 197: 96-106.
Hojo, Y.and Y. Satomi. 1991. In vivo nephrotoxicity induced in mice by chromium(VI). Involvement of glutathione and chromium(V). Biol Trace Elem Res. 31: 21-31.
Huang, Y.L., C.Y. Chen, J.Y. Sheu, I.C. Chuang, J.H. Pan, and T.H. Lin. 1999. Lipid peroxidation in workers exposed to hexavalent chromium. J Toxicol Environ Health A. 56: 235-247.
Ito, K.and S. Kawanishi. 1997. Site-specific DNA damage induced by UVA radiation in the presence of endogenous photosensitizer. Biol Chem. 378: 1307-1312.
Izzotti, A., M. Bagnasco, A. Camoirano, M. Orlando, and S. De Flora. 1998. DNA fragmentation, DNA-protein crosslinks, postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine. Mutat Res. 400: 233-244.
Kastan, M.B., O. Onyekwere, D. Sidransky, B. Vogelstein, and R.W. Craig. 1991. Participation of p53 protein in the cellular response to DNA damage. Cancer Res. 51: 6304-6311.
Kawanishi, S., S. Inoue, and S. Sano. 1986. Mechanism of DNA cleavage induced by sodium chromate(VI) in the presence of hydrogen peroxide. J Biol Chem. 261: 5952-5958.
Kerger, B.D., R.O. Richter, S.M. Chute, D.G Dodge, S.K. Overman, J. Liang, B.L. Finley, and D.J. Paustenbach. 1996. Refined exposure assessment for ingestion of tapwater contaminated with hexavalent chromium: consideration of exogenous and endogenous reducing agents. J Expo Anal Environ Epidemiol. 6: 163-179.
Kim, E.and K.J. Na. 1991. Nephrotoxicity of sodium dichromate depending on the route of administration. Arch Toxicol. 65: 537-541.
Kohen. R.and A. Nyska. 2002. Oxidation of biological systems: oxidative stress phenomena, antioxidants, redox reactions, and methods for their quantification. Toxicol Pathol. 30: 620-650.
Lawler, J.M., W. Song, and S.R. Demaree. 2003. Hindlimb unloading increases oxidative stress and disrupts antioxidant capacity in skeletal muscle. Free Radic Biol Med. 35: 9-16.
Lennon, S.V., S.J. Martin, and T.G Cotter. 1991. Dose-dependent induction of apoptosis in human tumour cell lines by widely diverging stimuli. Cell Prolif. 24: 203-214.
Levina, A., RA. Lay, and N.E. Dixon. 2001. Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro. Chem Res Toxicol. 14:946-950.
Li, G, L. Li, and D. Yin. 2005a. A novel observation: melatonin's interaction with malondiadehyde. Neuro Endocrinol Lett. 26: 61-66.
Li, L.J., F. Zhang, X.M. Liu, Y.P. Guo, and E.B. Ma. 2005b. Oxidative stress related enzymes in response to chromium (VI) toxicity in Oxya chinensis (Orthoptera: Acridoidae). J Environ Sci (China). 17: 823-826.
Marklund, S.and G Marklund. 1974. Involvement of the superoxide anion radical in the autoxidation of pyrogallol and a convenient assay for superoxide dismutase. Eur J Biochem. 47: 469-474.
Matsuoka, S., G Rotman, A. Ogawa, Y. Shiloh, K. Tamai, and S.J. Elledge. 2000. Ataxia telangiectasia-mutated phosphorylates Chk2 in vivo and in vitro. Proc Natl Acad Sci U S A. 97: 10389-10394.
Merk, O., K. Reiser, and G Speit. 2000. Analysis of chromate-induced DNA-protein crosslinks with the comet assay. Mutat Res. 471: 71-80.
Mihara, M., S. Erster, A. Zaika, O. Petrenko, T. Chittenden, P. Pancoska, and U.M. Moll. 2003. p53 has a direct apoptogenic role at the mitochondria. Mol Cell. 11: 577-590.
Milczarek, GJ., J. Martinez, and GT. Bowden. 1997. p53 Phosphorylation: biochemical and functional consequences. Life Sci. 60: 1-11.
Miyamae, Y, K. Iwasaki, N. Kinae, S. Tsuda, M. Murakami, M. Tanaka, and Y.F. Sasaki. 1997. Detection of DNA lesions induced by chemical mutagens using the single-cell gel electrophoresis (comet) assay. 2. Relationship between DNA migration and alkaline condition. Mutat Res. 393: 107-113.
Nordberg, J.and E.S. Arner. 2001. Reactive oxygen species, antioxidants, and the mammalian thioredoxin system. Free Radic Biol Med. 31: 1287-1312.
O'Brien, T., H.G Mandel, D.E. Pritchard, and S.R. Patierno. 2002. Critical role of chromium (Cr)-DNA interactions in the formation of Cr-induced polymerase arresting lesions. Biochemistry. 41: 12529-12537.
O'Brien, T.J., S. Ceryak, and S.R. Patierno. 2003. Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms. Mutat Res. 533: 3-36.
Ohkawa, H., N. Ohishi, and K. Yagi. 1979. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Anal Biochem. 95: 351-358.
Pandey, V., V. Dixit, and R. Shyam. 2005. Antioxidative responses in relation to growth of mustard (Brassica juncea cv. Pusa Jaikisan) plants exposed to hexavalent chromium. Chemosphere. 61: 40-47.
Park, R.M., J.F. Bena, L.T. Stayner, R.J. Smith, H.J. Gibb, and P.S. Lees. 2004. Hexavalent chromium and lung cancer in the chromate industry: a quantitative risk assessment. Risk Anal. 24: 1099-1108.
Paustenbach, D.J., B.L. Finley, F.S. Mowat, and B.D. Kerger. 2003. Human health risk and exposure assessment of chromium (VI) in tap water. J Toxicol Environ Health A. 66: 1295-1339.
Petrilli, F.L.and S. de Flora. 1988. Metabolic reduction of chromium as a threshold mechanism limiting its in vivo activity. Sci Total Environ. 71: 357-364.
Philchenkov, A. 2004. Caspases: potential targets for regulating cell death. J Cell Mol Med. 8: 432-444.
Quievryn, G, E. Peterson, J. Messer, and A. Zhitkovich. 2003. Genotoxicity and mutagenicity of chromium(VI)/ascorbate-generated DNA adducts in human and bacterial cells. Biochemistry. 42: 1062-1070.
Riedl, S.J.and Y. Shi. 2004. Molecular mechanisms of caspase regulation during apoptosis. Nat Rev Mol Cell Biol. 5: 897-907.
Rowbotham, A.L., L.S. Levy, and L.K. Shuker. 2000. Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects. J Toxicol Environ Health B Crit Rev. 3: 145-178.
Rudolf, E., M. Cervinka, J. Cerman, and L. Schroterova. 2005. Hexavalent chromium disrupts the actin cytoskeleton and induces mitochondria-dependent apoptosis in human dermal fibroblasts. Toxicol In Vitro. 19:713-723.
Shi, X., S.S. Leonard, K.J. Liu, L. Zang, P.M. Gannett, and Y. Rojanasakul. 1998. Cr(III)-mediated hydroxyl radical generation via Haber-Weiss cycle. Journal of Inorganic Biochemistry. 69: 263-268.
Shi, X.L.and N.S. Dalai. 1992. The role of superoxide radical in chromium (VI)-generated hydroxyl radical: the Cr(VI) Haber-Weiss cycle. Arch Biochem Biophys. 292: 323-327.
Singh, N.P., M.T. McCoy, R.R. Tice, and E.L. Schneider. 1988. A simple technique for quantitation of low levels of DNA damage in individual cells. Exp Cell Res. 175: 184-191.
Sinha, S., R. Saxena, and S. Singh. 2005. Chromium induced lipid peroxidation in the plants of Pistia stratiotes L.: role of antioxidants and antioxidant enzymes. Chemosphere. 58: 595-604.
Sugden, K.D.and K.E. Wetterhahn. 1997. Direct and hydrogen peroxide-induced chromium(V) oxidation of deoxyribose in single-stranded and double-stranded calf thymus DNA. Chem Res Toxicol. 10: 1397-1406.
Susa, N., S. Ueno, Y. Furukawa, N. Michiba, and S. Minoura. 1989. Induction of lipid peroxidation in mice by hexavalent chromium and its relation to the toxicity. Nippon Juigaku Zasshi. 51: 1103-1110.
Susin, S.A., E. Daugas, L. Ravagnan, K. Samejima, N. Zamzami, M. Loeffler, P. Costantini, K.F. Ferri, T. Irinopoulou, M.C. Prevost, G. Brothers, T.W. Mak, J. Penninger, W.C. Earnshaw, and G Kroemer. 2000. Two distinct pathways leading to nuclear apoptosis. J Exp Med. 192: 571-580.
Thomenius, M.J.and C.W. Distelhorst. 2003. Bcl-2 on the endoplasmic reticulum: protecting the mitochondria from a distance. J Cell Sci. 116: 4493-4499.
Travacio, M., J.M. Polo, and S. Llesuy. 2001. Chromium (VI) induces oxidative stress in the mouse brain. Toxicology. 162: 139-148.
van Gurp, M., N. Festjens G van Loo, X. Saelens, and P. Vandenabeele. 2003. Mitochondrial intermembrane proteins in cell death. Biochem Biophys Res Commun. 304: 487-497.
Wang, S., S.S. Leonard, J. Ye, M. Ding, and X. Shi. 2000. The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation. Am J Physiol Cell Physiol. 279: C868-875.
Wang, S., S.S. Leonard, J. Ye, N. Gao, L. Wang, and X. Shi. 2004. Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction. Mol Cell Biochem. 255: 119-127.
Wang, S.and X. Shi. 2001. Mechanisms of Cr(VI)-induced p53 activation: the role of phosphorylation, mdm2 and ERK. Carcinogenesis. 22:757-762.
Xu, J., F.C. Manning, and S.R. Patierno. 1994. Preferential formation and repair of chromium-induced DNA adducts and DNA-protein crosslinks in nuclear matrix DNA. Carcinogenesis. 15: 1443-1450.
Ye, J., S. Wang, S.S. Leonard, Y. Sun, L. Butterworth, J. Antonini, M. Ding, Y. Rojanasakul, V. Vallyathan, V. Castranova, and X. Shi. 1999. Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis. J Biol Chem. 274: 34974-34980.
Yu, J.and L. Zhang. 2005. The transcriptional targets of p53 in apoptosis control. Biochem Biophys Res Commun. 331:851-858.
Zhang, H., J. Heim, and B. Meyhack. 1998. Redistribution of Bax from cytosol to membranes is induced by apoptotic stimuli and is an early step in the apoptotic pathway. Biochem Biophys Res Commun. 251: 454-459.
Zhitkovich, A. 2005. Importance of chromium-DNA adducts in mutagenicity and toxicity of chromium(VI). Chem Res Toxicol. 18: 3-11.
Zhitkovich, A., G. Quievryn, J. Messer, and Z. Motylevich. 2002. Reductive activation with cysteine represents a chromium(HI)-dependent pathway in the induction of genotoxicity by carcinogenic chromium(VI). Environ Health Perspect. 110 Suppl 5: 729-731.
Zhitkovich, A., S. Shrager, and J. Messer. 2000. Reductive metabolism of Cr(VI) by cysteine leads to the formation of binary and ternary Cr-DNA adducts in the absence of oxidative DNA damage. Chem Res Toxicol. 13: 1114-1124.
Zhitkovich, A., Y. Song, G Quievryn, and V. Voitkun. 2001. Non-oxidative mechanisms are responsible for the induction of mutagenesis by reduction of Cr(VI) with cysteine: role of ternary DNA adducts in Cr(III)-dependent mutagenesis. Biochemistry. 40: 549-560.
Arakawa, H., R. Ahmad, M. Naoui, and H.A. Tajmir-Riahi. 2000. A comparative study of calf thymus DNA binding to Cr(III) and Cr(VI) ions. Evidence for the guanine N-7-chromium-phosphate chelate formation. J Biol Chem. 275: 10150-10153.
Bose, R.N., S. Moghaddas, P.A. Mazzer, L.P. Dudones, L. Joudah, and D. Stroup. 1999. Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation. Nucleic Acids Res. 27: 2219-2226.
Celander, D.W.and T.R. Cech. 1990. Iron(II)-ethylenediaminetetraacetic acid catalyzed cleavage of RNA and DNA oligonucleotides: similar reactivity toward single- and double-stranded forms. Biochemistry. 29: 1355-1361.
Costa, M. 2003. Potential hazards of hexavalent chromate in our drinking water. Toxicol Appl Pharmacol. 188: 1-5.
de la Sienra, E., M.A. Armienta, and M.E. Gonsebatt. 2003. Potassium dichromate increases the micronucleus frequency in the crayfish Procambarus clarkii. Environ Pollut. 126: 367-370.
Fornace, A.J., Jr., D.S. Seres, J.F. Lechner, and C.C. Harris. 1981. DNA-protein cross-linking by chromium salts. Chem Biol Interact. 36: 345-354.
Gajewski, E.and M. Dizdaroglu. 1990. Hydroxyl radical induced cross-linking of cytosine and tyrosine in nucleohistone. Biochemistry. 29: 977-980.
Ha, L., S. Ceryak, and S.R. Patierno. 2003. Chromium (VI) activates ataxia telangiectasia mutated (ATM) protein. Requirement of ATM for both apoptosis and recovery from terminal growth arrest. J Biol Chem. 278: 17885-17894.
Hamilton, J.W.and K.E. Wetterhahn. 1986. Chromium (VI)-induced DNA damage in chick embryo liver and blood cells in vivo. Carcinogenesis. 7: 2085-2088.
Hook, S.E.and R.F. Lee. 2004. Genotoxicant induced DNA damage and repair in early and late developmental stages of the grass shrimp Paleomonetes pugio embryo as measured by the comet assay. Aquat Toxicol. 66: 1-14.
Ito, K.and S. Kawanishi. 1997. Site-specific DNA damage induced by UVA radiation in the presence of endogenous photosensitizer. Biol Chem. 378: 1307-1312.
Izzotti, A., M. Bagnasco, A. Camoirano, M. Orlando, and S. De Flora. 1998. DNA fragmentation, DNA-protein crosslinks, postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine. Mutat Res. 400: 233-244.
Kawanishi, S., S. Inoue, and S. Sano. 1986. Mechanism of DNA cleavage induced by sodium chromate(VI) in the presence of hydrogen peroxide. J Biol Chem. 261: 5952-5958.
Koster, A.and D. Beyersmann. 1985. Chromium binding by calf thymus nuclei and effects on chromatin. Toxicol. Environ. Che. 10: 307-313.
Levina, A., P.A. Lay, and N.E. Dixon. 2001. Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro. Chem Res Toxicol. 14: 946-950.
Liu, K., J. Husler, J. Ye, S.S. Leonard, D. Cutler, F. Chen, S. Wang, Z. Zhang, M. Ding, L. Wang, and X. Shi. 2001. On the mechanism of Cr (VI)-induced carcinogenesis: dose dependence of uptake and cellular responses. Mol Cell Biochem. 222: 221-229.
O'Brien, T., H.G. Mandel, D.E. Pritchard, and S.R. Patierno. 2002a. Critical role of chromium (Cr)-DNA interactions in the formation of Cr-induced polymerase arresting lesions. Biochemistry. 41: 12529-12537.
O'Brien, T., J. Xu, and S.R. Patierno. 2001. Effects of glutathione on chromium-induced DNA crosslinking and DNA polymerase arrest. Mol Cell Biochem. 222: 173-182.
O'Brien, T.J., S. Ceryak, and S.R. Patierno. 2003. Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms. Mutat Res. 533: 3-36.
O'Brien, T.J., J.L. Fornsaglio, S. Ceryak, and S.R. Patierno. 2002b. Effects of hexavalent chromium on the survival and cell cycle distribution of DNA repair-deficient S. cerevisiae. DNA Repair (Amst). 1: 617-627.
Pritchard, D.E., S. Ceryak, L. Ha, J.L. Fornsaglio, S.K. Hartman, T.J. O'Brien, and S.R. Patierno. 2001. Mechanism of apoptosis and determination of cellular fate in chromium(VI)-exposed populations of telomerase-immortalized human fibroblasts. Cell Growth Differ.-12: 487-496.
Quievryn, G., J. Messer, and A. Zhitkovich. 2002. Carcinogenic chromium(VI) induces cross-linking of vitamin C to DNA in vitro and in human lung A549 cells. Biochemistry. 41:3156-3167.
Quievryn, G., E. Peterson, J. Messer, and A. Zhitkovich. 2003. Genotoxicity and mutagenicity of chromium(VI)/ascorbate-generated DNA adducts in human and bacterial cells. Biochemistry. 42: 1062-1070.
Salnikow, K., A. Zhitkovich, and M. Costa. 1992. Analysis of the binding sites of chromium to DNA and protein in vitro and in intact cells. Carcinogenesis. 13: 2341-2346.
Snow, E.T.and L.S. Xu. 1991. Chromium(III) bound to DNA templates promotes increased polymerase processivity and decreased fidelity during replication in vitro. Biochemistry. 30: 11238-11245.
Strauss, J.K.and L.J. Maher, 3rd. 1994. DNA bending by asymmetric phosphate neutralization. Science. 266: 1829-1834.
Sugden, K.D., C.K. Campo, and B.D. Martin. 2001. Direct oxidation of guanine and 7,8-dihydro-8-oxoguanine in DNA by a high-valent chromium complex: a possible mechanism for chromate genotoxicity. Chem Res Toxicol. 14: 1315-1322.
Sugden, K.D.and B.D. Martin. 2002. Guanine and 7,8-dihydro-8-oxo-guanine-specific oxidation in DNA by chromium(V). Environ Health Perspect. 110 Suppl 5: 725-728.
Sugden, K.D.and K.E. Wetterhahn. 1997. Direct and hydrogen peroxide-induced chromium(V) oxidation of deoxyribose in single-stranded and double-stranded caif thymus DNA. Chem Res Toxicol. 10:1397-1406.
Tsou, T.C., H.J. Lai, and J.L. Yang. 1999. Effects of mannitol or catalase on the generation of reactive oxygen species leading to DNA damage by Chromium(VI) reduction with ascorbate. Chem Res Toxicol. 12: 1002-1009.
Ueno, S., T. Kashimoto, N. Susa, Y. Furukawa, M. Ishii, K. Yokoi, M. Yasuno, Y.F. Sasaki, J.
Ueda, Y. Nishimura, and M. Sugiyama. 2001. Detection of dichromate (Vl)-induced DNA strand breaks and formation of paramagnetic chromium in multiple mouse organs. Toxicol Appl Pharmacol. 170: 56-62.
Voitkun, V., A. Zhitkovich, and M. Costa. 1998. Cr(III)-mediated crosslinks of glutathione or amino acids to the DNA phosphate backbone are mutagenic in human cells. Nucleic Acids Res. 26: 2024-2030.
Xu, J., F.C. Manning, and S.R. Patierno. 1994. Preferential formation and repair of chromium-induced DNA adducts and DNA-protein crosslinks in nuclear matrix DNA. Carcinogenesis. 15: 1443-1450.
Zhitkovich, A., G. Quievryn, J. Messer, and Z. Motylevich. 2002. Reductive activation with cysteine represents a chromium(III)-dependent pathway in the induction of genotoxicity by carcinogenic chromium(VI). Environ Health Perspect. 110 Suppl 5: 729-731.
Zhitkovich, A., S. Shrager, and J. Messer. 2000. Reductive metabolism of Cr(VI) by cysteine leads to the formation of binary and ternary Cr-DNA adducts in the absence of oxidative DNA damage. Chem Res Toxicol. 13:1114-1124.
Zhitkovich, A., Y. Song, G. Quievryn, and V. Voitkun. 2001. Non-oxidative mechanisms are responsible for the induction of mutagenesis by reduction of Cr(VI) with cysteine: role of ternary DNA adducts in Cr(III)-dependent mutagenesis. Biochemistry. 40: 549-560.
Zhitkovich, A., V. Voitkun, and M. Costa. 1995. Glutathione and free amino acids form stable complexes with DNA following exposure of intact mammalian cells to chromate. Carcinogenesis. 16: 907-913.
Zhitkovich, A.. V. Voitkun, and M. Costa. 1996. Formation of the amino acid-DNA complexes by hexavalent and trivalent chromium in vitro: importance of trivalent chromium and the phosphate group. Biochemistry. 35: 7275-7282.
Zhitkovich, A., V. Voitkun, T. Kluz, and M. Costa. 1998. Utilization of DNA-protein cross-links as a biomarker of chromium exposure. Environ Health Perspect. 106 Suppl 4: 969-974.
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Anuradha, C.D., S. Kanno, and S. Hirano. 2001. Oxidative damage to mitochondria is a preliminary step to caspase-3 activation in fluoride-induced apoptosis in HL-60 cells. Free Radic Biol Med. 31: 367-373.
Arakawa, H., F. Wu, M. Costa, W. Rom, and M.S. Tang. 2006. Sequence specificity of Cr(Ⅲ)-DNA adduct formation in the p53 gene: NGG sequences are preferential adduct-forming sites. Carcinogenesis. 27: 639-645.
Bagchi, D., J. Balmoori, M. Bagchi, X. Ye, C.B. Williams, and S.J. Stohs. 2000. Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (Ⅵ) in liver and brain tissues of mice. Free Radic Biol Med. 28: 895-903.
Bagchi, D., S.J. Stohs, B.W. Downs, M. Bagchi, and H.G. Preuss. 2002. Cytotoxicity and oxidative mechanisms of different forms of chromium. Toxicology. 180: 5-22.
Banin, S.,L. Moyal, S. Shieh, Y. Taya, C.W. Anderson, L. Chessa, N.I. Smorodinsky, C. Prives, Y. Reiss, Y. Shiloh, and Y. Ziv. 1998. Enhanced phosphorylation of p53 by ATM in response to DNA damage. Science. 281: 1674-1677.
Brady, H.J.and G. Gil-Gomez. 1998. Bax. The pro-apoptotic Bcl-2 family member, Bax. Int J Biochem Cell Biol. 30: 647-650.
Carlisle, D.L., D.E. Pritchard, J. Singh, B.M. Owens, L.J. Blankenship, J.M. Orenstein, and S.R. Patierno. 2000a. Apoptosis and P53 induction in human lung fibroblasts exposed to chromium (Ⅵ): effect of ascorbate and tocopherol. Toxicol Sci. 55: 60-68.
Carlisle, D.L., D.E. Pritchard, J. Singh, and S.R. Patierno. 2000b. Chromium(Ⅵ) induces p53-dependent apoptosis in diploid human lung and mouse dermal fibroblasts. Mol Carcinog. 28:111-118.
Ceryak, S., C. Zingariello, T. O'Brien, and S.R. Patierno. 2004. Induction of pro-apoptotic and cell cycle-inhibiting genes in chromium (VI)-treated human lung fibroblasts: lack of effect of ERK. Mol Cell Biochem. 255: 139-149.
Ding, M.and X. Shi. 2002. Molecular mechanisms of Cr(VI)-induced carcinogenesis. Mol Cell Biochem. 234-235: 293-300.
Donald, S.P., X.Y. Sun, C.A. Hu, J. Yu, J.M. Mei, D. Valle, and J.M. Phang. 2001. Proline oxidase, encoded by p53-induced gene-6, catalyzes the generation of proline-dependent reactive oxygen species. Cancer Res. 61: 1810-1815.
Feng, Z., W. Hu, W.N. Rom, M. Costa, and M.S. Tang. 2003. Chromium(VI) exposure enhances polycyclic aromatic hydrocarbon-DNA binding at the p53 gene in human lung cells. Carcinogenesis. 24: 771-778.
Foo, S.Y.and GP. Nolan. 1999. NF-kappaB to the rescue: RELs, apoptosis and cellular transformation. Trends Genet. 15: 229-235.
Gambelunghe, A., R. Piccinini, G. Abbritti, M. Ambrogi, B. Ugolini, C. Marchetti, G Migliorati, C. Balducci, and G Muzi. 2006. Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4). J Occup Environ Med. 48: 319-325.
Gunaratnam, M.and M.H. Grant. 2002. Chromium(VI)-induced damage to the cytoskeleton and cell death in isolated hepatocytes. Biochem Soc Trans. 30: 748-750.
Ha, L., S. Ceryak, and S.R. Patierno. 2003. Chromium (VI) activates ataxia telangiectasia mutated (ATM) protein. Requirement of ATM for both apoptosis and recovery from terminal growth arrest. J Biol Chem. 278: 17885-17894.
Haupt, Y., A.I. Robles, C. Prives, and V. Rotter. 2002. Deconstruction of p53 functions and regulation. Oncogene. 21: 8223-8231.
Hayashi, Y., T. Kondo, Q.L. Zhao, R. Ogawa, Z.G Cui, L.B. Feril, Jr., H. Teranishi, and M. Kasuya. 2004. Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells. Toxicol Appl Pharmacol. 197: 96-106.
lzzotti, A., M. Bagnasco, C. Cartiglia, M. Longobardi, and S. De Flora. 2004. Proteomic analysis as related to transcriptome data in the lung of chromium(Ⅵ)-treated rats. Int J Oncol. 24: 1513-1522.
Khosravi, R., R. Maya, T. Gottlieb, M. Oren, Y. Shiloh, and D. Shkedy. 1999. Rapid ATM-dependent phosphorylation of MDM2 precedes p53 accumulation in response to DNA damage. Proc Natl Acad Sci U S A. 96: 14973-14977.
Matsuoka, S., G. Rotman, A. Ogawa, Y. Shiloh, K. Tamai, and S.J. Elledge. 2000. Ataxia telangiectasia-mutated phosphorylates Chk2 in vivo and in vitro. Proc Natl Acad Sci U S A. 97: 10389-10394.
Norbury, C.J.and B. Zhivotovsky. 2004. DNA damage-induced apoptosis. Oncogene. 23:2797-2808.
Polyak, K., Y. Xia, J.L. Zweier, K.W. Kinzler, and B. Vogelstein. 1997. A model for p53-induced apoptosis. Nature. 389: 300-305.
Pritchard, D.E., J. Singh, D.L. Carlisle, and S.R. Patierno. 2000. Cyclosporin A inhibits chromium(Ⅵ)-induced apoptosis and mitochondrial cytochrome c release and restores clonogenic survival in CHO cells. Carcinogenesis. 21: 2027-2033.
Rudolf, E.and M. Cervinka. 2006. The role of intracellular zinc in chromium(Ⅵ)-induced oxidative stress, DNA damage and apoptosis. Chem Biol Interact. 162: 212-227.
Rudolf, E., M. Cervinka, J. Cerman, and L. Schroterova. 2005. Hexavalent chromium disrupts the actin cytoskeleton and induces mitochondria-dependent apoptosis in human dermal fibroblasts. Toxicol In Vitro. 19: 713-723.
Russo, P., A. Catassi, A. Cesario, A. Imperatori, N. Rotolo, M. Fini, P. Granone, and L. Dominioni. 2005. Molecular mechanisms of hexavalent chromium-induced apoptosis in human bronchoalveolar cells. Am J Respir Cell Mol Biol. 33: 589-600.
Shimada, H., Y.H. Shiao, M. Shibata, and M.P. Waalkes. 1998. Cadmium suppresses apoptosis induced by chromium. J Toxicol Environ Health A. 54: 159-168.
Wang, S., F. Chen, Z. Zhang, B.H. Jiang, L. Jia, and X. Shi. 2004a. NF-kappaB prevents cells from undergoing Cr(VI)-induced apoptosis. Mol Cell Biochem. 255: 129-137.
Wang, S., S.S. Leonard, J. Ye, M. Ding, and X. Shi. 2000. The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation. Am J Physiol Cell Physiol. 279: C868-875.
Wang, S., S.S. Leonard, J. Ye, N. Gao, L. Wang, and X. Shi. 2004b. Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction. Mol Cell Biochem. 255: 119-127.
Wang, S.and X. Shi. 2001. Mechanisms of Cr(VI)-induced p53 activation: the role of phosphorylation, mdm2 and ERK. Carcinogenesis. 22: 757-762.
Ye, J.and X. Shi. 2001. Gene expression profile in response to chromium-induced cell stress in A549 cells. Mol Cell Biochem. 222: 189-197.
Ye, J., S. Wang, S.S. Leonard, Y. Sun, L. Butterworth, J. Antonini, M. Ding, Y. Rojanasakul, V. Vallyathan, V. Castranova, and X. Shi. 1999. Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis. J Biol Chem. 274: 34974-34980.
Yu, J.and L. Zhang. 2005. The transcriptional targets of p53 in apoptosis control. Biochem Biophys Res Commun. 331: 851-858.
Zhang, H., J. Heim, and B. Meyhack. 1998. Redistribution of Bax from cytosol to membranes is induced by apoptotic stimuli and is an early step in the apoptotic pathway. Biochem Biophys Res Commun. 251:454-459.
杜良，王金生．2004．铬渣毒性对环境的影响与产出量分析[J]．安全与环境学报，4(2)；34-37．
金仁哲，李宝贵，玄长龙等．1994．一起六价铬污染饮用水引起中毒的报告[J]．中国国境卫生检疫杂志，17：14．
李梅莉，朗胜喜．2004．某厂铬酸盐对作业工人健康的影响[J]．职业与健康，20(4)：26-27．
梁群超，郭剑英，唐兆新．2006．自由基与细胞凋亡[J]．上海畜牧兽医通讯，4：41—43．
史黎薇．2003．铬化合物对健康影响的研究进展[J]．卫生研究，32(4)：410-412．
王家骏，叶丽杰，孙文娟，等．1998．铬致大鼠肾组织脂质过氧化作用[J]．卫生毒理学杂志，12(4)：261—262．
王筱冰，张小翠，夏妙红，等．2006．Caspase的活化机制[J]．现代生物医学进展，6(3)：53-55．
谢萍．2004．自由基与细胞凋亡[J]．生物学教学，29(1)：3-4．
张洪霞，钟才高，徐顺清，等．2006．Cr(Ⅵ)诱导肝细胞凋亡与氧化损伤、p53和半胱氨酸天冬氨酸蛋白酶3表达的关系[J]．中国药理学与毒理学杂志，20(2)：144-151．
张双华．2005．70％电子垃圾涌入我国污染使村民癌症高发[OL]．人民网-人民日报海外版，2005-8-8，http://www.chinabyte.com/450/2062450.shtml．
赵堃，柴立元，王云燕等．2006．水环境中铬的存在形态及迁移转化规律[J]．工业安全与环保，32(8)：1-3．
褚启龙，杨克敌，王爱国．2003．氧化应激与细胞凋亡关系的研究进展[J]．卫生研究，32(3)：
276—279
Arakawa, H., R. Ahmad, M. Naoui, and H.A. TajmiroRiahi. 2000. A comparative study of calf thymus
DNA binding to Cr(III) and Cr(VI) ions. Evidence for the guanine N-7-chromium-phosphate
chelate formation. J Biol Chem. 275: 10~50-10!53.
Bagchi, D., E.A. Hassoun, M. Bagchi, D.E Muldoon, and S.J. Stchs. !995a. Oxidative stress induced
by chronic administration of sodium dichromate [Cr(~1)] to rats. Comp Biochem Physiol C
Pharmacol Toxicol Endocrinol. 110: 281-287.
Bagchi, D., E.A. Hassoun, M. Bagchi, and S.J. Stohs. 1995b. Chromium-induced excretion of urinary lipid metabolites, DNA damage, nitric oxide production, and generation of reactive oxygen species in Sprague-Dawley rats. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 110: 177-187.
Banin, S., L. Moyal, S. Shieh, Y. Taya, CW. Anderson, L. Chessa, N.I. Smorodinsky, C. Prives, Y. Reiss, Y. Shiloh, and Y. Ziv. 1998. Enhanced phosphorylation of p53 by ATM in response to DNA damage. Science. 281: 1674-1677.
Barros, M.H., L.E. Netto, and A.J. Kowaltowski. 2003. H(2)O(2) generation in Saccharomyces cerevisiae respiratory pet mutants: effect of cytochrome c. Free Radic Biol Med. 35: 179-188.
Beck, M.A. 1999. Selenium and host defence towards viruses. Proc Nutr Soc. 58: 707-711.
Bjorkerud, B.and S. Bjorkerud. 1996. Contrary effects of lightly and strongly oxidized LDL with potent promotion of growth versus apoptosis on arterial smooth muscle cells, macrophages, and fibroblasts. Arterioscler Thromb Vasc Biol. 16: 416-424.
Blankert, S.A., V.H. Coryell, B.T. Picard, K.K. Wolf, R.E. Lomas, and D.M. Stearns. 2003. Characterization of nonmutagenic Cr(III)-DNA interactions. Chem Res Toxicol. 16: 847-854.
Bose, R.N., S. Moghaddas, P.A. Mazzer, L.P. Dudones, L. Joudah, and D. Stroup. 1999. Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation. Nucleic Acids Res. 27: 2219-2226.
Carlisle, D.L., DE. Pritchard, J. Singh, B.M. Owens, L.J. Blankenship, J.M. Orenstein, and S.R. Patierno. 2000. Apoptosis and P53 induction in human lung fibroblasts exposed to chromium (VI): effect of ascorbate and tocopherol. Toxicol Sci. 55: 60-68.
Casadevall, M., P. da Cruz Fresco, and A. Kortenkamp. 1999. Chromium(VI)-mediated DNA damage: oxidative pathways resulting in the formation of DNA breaks and abasic sites. Chem Biol Interact. 123: 117-132.
Celander, D.W.and T.R. Cech. 1990. Iron(II)-ethylenediaminetetraacetic acid catalyzed cleavage of RNA and DNA oligonucleotides: similar reactivity toward single- and double-stranded forms. Biochemistry. 29: 1355-1361.
Coogan, T.P., J. Motz, C.A. Snyder, K.S. Squibb, and M. Costa. 1991. Differential DNA-protein crosslinking in lymphocytes and liver following chronic drinking water exposure of rats to potassium chromate. Toxicol Appl Pharmacol. 109: 60-72.
Costa, M. 2003. Potential hazards of hexavalent chromate in our drinking water. Toxicol Appl Pharmacol. 188: 1-5.
Crump, C, K. Crump, E. Hack, R. Luippold, K. Mundt, E. Liebig, J. Panko, D. Paustenbach, and D. Proctor. 2003. Dose-response and risk assessment of airborne hexavalent chromium and lung cancer mortality. Risk Anal. 23: 1147-1163.
D'Agostini, F, A. Izzotti, C. Bennicelli, A. Camoirano, E. Tampa, and S. De Flora. 2002. Induction of apoptosis in the lung but not in the liver of rats receiving intra-tracheal instillations of chromium(VI). Carcinogenesis. 23: 587-593.
Dana Devi, K., R. Rozati, B. Saleha Banu, K. Jamil, and P. Grover. 2001. In vivo genotoxic effect of potassjum dichromate in mice leukocytes using comet assay. Food Chem Toxicol. 39: 859-865.
Dartsch, PC, S. Hildenbrand, R. Kimmel, and F.W. Schmahl. 1998. Investigations on the nephrotoxicity and hepatotoxicity of trivalent and hexavalent chromium compounds. Int Arch Occup Environ Health. 71 Suppl: S40-45.
das Neves, R.P., T.M. Santos, L. Pereira Mde, and J.P. de Jesus. 2002. Comparative histological studies on liver of mice exposed to Cr(VI) and Cr(V) compounds. Hum Exp Toxicol. 21: 365-369.
De Flora, S. 2000. Threshold mechanisms and site specificity in chromium(Vl) carcinogenesis. Carcinogenesis. 21: 533-541.
De Flora, S., GS. Badolati, D. Serra, A. Picciotto, M.R. Magnolia, and V. Savarino. 1987. Circadian reduction of chromium in the gastric environment. Mutat Res. 192: 169-174.
De Flora, S., A. Camoirano, M. Bagnasco, C. Bennicelli, G.E. Corbett, and B.D. Kerger. 1997. Estimates of the chromium(VI) reducing capacity in human body compartments as a mechanism for attenuating its potential toxicity and carcinogenicity. Carcinogenesis. 18: 531-537.
De Flora, S., D. Serra, A. Camoirano, and P. Zanacchi. 1989. Metabolic reduction of chromium, as related to its carcinogenic properties. Biol Trace Elem Res. 21: 179-187.
Ding, M.and X. Shi. 2002. Molecular mechanisms of Cr(VI)-induced carcinogenesis. Mol Cell Biochem. 234-235: 293-300.
Edremitlioglu, M., D. Kilic, S. Oter, U. Kisa, A. Korkmaz, O. Coskun, and O. Bedir. 2005. The effect of hyperbaric oxygen treatment on the renal functions in septic rats: relation to oxidative damage. Surg Today. 35:653-661.
Fan, T.J., L.H. Han, R.S. Cong, and J. Liang. 2005. Caspase family proteases and apoptosis. Acta Biochim Biophys Sin (Shanghai). 37: 719-727.
Febel, H., B. Szegedi, and S. Huszar. 2001. Absorption of inorganic, trivalent and hexavalent chromium following oral and intrajejunal doses in rats. Acta Vet Hung. 49: 203-209.
Feng, Z., W. Hu, W.N. Rom, M. Costa, and M.S. Tang. 2003. Chromium(VI) exposure enhances polycyclic aromatic hydrocarbon-DNA binding at the p53 gene in human lung cells. Carcinogenesis. 24: 771-778.
Finkel, T. 2003. Oxidant signals and oxidative stress. Curr Opin Cell Biol. 15: 247-254.
Fornace, A.J., Jr., D.S. Seres, J.F. Lechner, and C.C. Harris. 1981. DNA-protein cross-linking by chromium salts. Chem Biol Interact. 36: 345-354.
Fridman, J.S.and S.W. Lowe. 2003. Control of apoptosis by p53. Oncogene. 22: 9030-9040.
Gambelunghe, A., R. Piccinini, G Abbritti, M. Ambrogi, B. Ugolini, C. Marchetti, G Migliorati, C. Balducci, and G. Muzi. 2006. Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4). J Occup Environ Med. 48:319-325.
Goulart, M., M.C. Batoreu, A.S. Rodrigues, A. Laires, and J. Rueff. 2005. Liponeroxidation products and thiol antioxidants in chromium exposed workers. Mutagenesis. 20: 311-315.
Gunaratnam, M.and M.H. Grant. 2002. Chromium(VI)-inducerl damage to the cytoskeleton and cell death in isolated hepatocytes. Biochem Soc Trans. 30: 748-750.
Hayashi, Y., T. Kondo, Q.L. Zhao, R. Ogawa, Z.G. Cui, L.B. Feril, Jr., H. Teranishi, and M. Kasuya. 2004. Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells. Toxicol Appl Pharmacol. 197: 96-106.
Hojo, Y.and Y. Satomi. 1991. In vivo nephrotoxicity induced in mice by chromium(VI). Involvement of glutathione and chromium(V). Biol Trace Elem Res. 31: 21-31.
Huang, Y.L., C.Y. Chen, J.Y. Sheu, I.C. Chuang, J.H. Pan, and T.H. Lin. 1999. Lipid peroxidation in workers exposed to hexavalent chromium. J Toxicol Environ Health A. 56: 235-247.
Ito, K.and S. Kawanishi. 1997. Site-specific DNA damage induced by UVA radiation in the presence of endogenous photosensitizer. Biol Chem. 378: 1307-1312.
Izzotti, A., M. Bagnasco, A. Camoirano, M. Orlando, and S. De Flora. 1998. DNA fragmentation, DNA-protein crosslinks, postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine. Mutat Res. 400: 233-244.
Kastan, M.B., O. Onyekwere, D. Sidransky, B. Vogelstein, and R.W. Craig. 1991. Participation of p53 protein in the cellular response to DNA damage. Cancer Res. 51: 6304-6311.
Kawanishi, S., S. Inoue, and S. Sano. 1986. Mechanism of DNA cleavage induced by sodium chromate(VI) in the presence of hydrogen peroxide. J Biol Chem. 261: 5952-5958.
Kerger, B.D., R.O. Richter, S.M. Chute, D.G Dodge, S.K. Overman, J. Liang, B.L. Finley, and D.J. Paustenbach. 1996. Refined exposure assessment for ingestion of tapwater contaminated with hexavalent chromium: consideration of exogenous and endogenous reducing agents. J Expo Anal Environ Epidemiol. 6: 163-179.
Kim, E.and K.J. Na. 1991. Nephrotoxicity of sodium dichromate depending on the route of administration. Arch Toxicol. 65: 537-541.
Kohen. R.and A. Nyska. 2002. Oxidation of biological systems: oxidative stress phenomena, antioxidants, redox reactions, and methods for their quantification. Toxicol Pathol. 30: 620-650.
Lawler, J.M., W. Song, and S.R. Demaree. 2003. Hindlimb unloading increases oxidative stress and disrupts antioxidant capacity in skeletal muscle. Free Radic Biol Med. 35: 9-16.
Lennon, S.V., S.J. Martin, and T.G Cotter. 1991. Dose-dependent induction of apoptosis in human tumour cell lines by widely diverging stimuli. Cell Prolif. 24: 203-214.
Levina, A., RA. Lay, and N.E. Dixon. 2001. Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro. Chem Res Toxicol. 14:946-950.
Li, G, L. Li, and D. Yin. 2005a. A novel observation: melatonin's interaction with malondiadehyde. Neuro Endocrinol Lett. 26: 61-66.
Li, L.J., F. Zhang, X.M. Liu, Y.P. Guo, and E.B. Ma. 2005b. Oxidative stress related enzymes in response to chromium (VI) toxicity in Oxya chinensis (Orthoptera: Acridoidae). J Environ Sci (China). 17: 823-826.
Marklund, S.and G Marklund. 1974. Involvement of the superoxide anion radical in the autoxidation of pyrogallol and a convenient assay for superoxide dismutase. Eur J Biochem. 47: 469-474.
Matsuoka, S., G Rotman, A. Ogawa, Y. Shiloh, K. Tamai, and S.J. Elledge. 2000. Ataxia telangiectasia-mutated phosphorylates Chk2 in vivo and in vitro. Proc Natl Acad Sci U S A. 97: 10389-10394.
Merk, O., K. Reiser, and G Speit. 2000. Analysis of chromate-induced DNA-protein crosslinks with the comet assay. Mutat Res. 471: 71-80.
Mihara, M., S. Erster, A. Zaika, O. Petrenko, T. Chittenden, P. Pancoska, and U.M. Moll. 2003. p53 has a direct apoptogenic role at the mitochondria. Mol Cell. 11: 577-590.
Milczarek, GJ., J. Martinez, and GT. Bowden. 1997. p53 Phosphorylation: biochemical and functional consequences. Life Sci. 60: 1-11.
Miyamae, Y, K. Iwasaki, N. Kinae, S. Tsuda, M. Murakami, M. Tanaka, and Y.F. Sasaki. 1997. Detection of DNA lesions induced by chemical mutagens using the single-cell gel electrophoresis (comet) assay. 2. Relationship between DNA migration and alkaline condition. Mutat Res. 393: 107-113.
Nordberg, J.and E.S. Arner. 2001. Reactive oxygen species, antioxidants, and the mammalian thioredoxin system. Free Radic Biol Med. 31: 1287-1312.
O'Brien, T., H.G Mandel, D.E. Pritchard, and S.R. Patierno. 2002. Critical role of chromium (Cr)-DNA interactions in the formation of Cr-induced polymerase arresting lesions. Biochemistry. 41: 12529-12537.
O'Brien, T.J., S. Ceryak, and S.R. Patierno. 2003. Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms. Mutat Res. 533: 3-36.
Ohkawa, H., N. Ohishi, and K. Yagi. 1979. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Anal Biochem. 95: 351-358.
Pandey, V., V. Dixit, and R. Shyam. 2005. Antioxidative responses in relation to growth of mustard (Brassica juncea cv. Pusa Jaikisan) plants exposed to hexavalent chromium. Chemosphere. 61: 40-47.
Park, R.M., J.F. Bena, L.T. Stayner, R.J. Smith, H.J. Gibb, and P.S. Lees. 2004. Hexavalent chromium and lung cancer in the chromate industry: a quantitative risk assessment. Risk Anal. 24: 1099-1108.
Paustenbach, D.J., B.L. Finley, F.S. Mowat, and B.D. Kerger. 2003. Human health risk and exposure assessment of chromium (VI) in tap water. J Toxicol Environ Health A. 66: 1295-1339.
Petrilli, F.L.and S. de Flora. 1988. Metabolic reduction of chromium as a threshold mechanism limiting its in vivo activity. Sci Total Environ. 71: 357-364.
Philchenkov, A. 2004. Caspases: potential targets for regulating cell death. J Cell Mol Med. 8: 432-444.
Quievryn, G, E. Peterson, J. Messer, and A. Zhitkovich. 2003. Genotoxicity and mutagenicity of chromium(VI)/ascorbate-generated DNA adducts in human and bacterial cells. Biochemistry. 42: 1062-1070.
Riedl, S.J.and Y. Shi. 2004. Molecular mechanisms of caspase regulation during apoptosis. Nat Rev Mol Cell Biol. 5: 897-907.
Rowbotham, A.L., L.S. Levy, and L.K. Shuker. 2000. Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects. J Toxicol Environ Health B Crit Rev. 3: 145-178.
Rudolf, E., M. Cervinka, J. Cerman, and L. Schroterova. 2005. Hexavalent chromium disrupts the actin cytoskeleton and induces mitochondria-dependent apoptosis in human dermal fibroblasts. Toxicol In Vitro. 19:713-723.
Shi, X., S.S. Leonard, K.J. Liu, L. Zang, P.M. Gannett, and Y. Rojanasakul. 1998. Cr(III)-mediated hydroxyl radical generation via Haber-Weiss cycle. Journal of Inorganic Biochemistry. 69: 263-268.
Shi, X.L.and N.S. Dalai. 1992. The role of superoxide radical in chromium (VI)-generated hydroxyl radical: the Cr(VI) Haber-Weiss cycle. Arch Biochem Biophys. 292: 323-327.
Singh, N.P., M.T. McCoy, R.R. Tice, and E.L. Schneider. 1988. A simple technique for quantitation of low levels of DNA damage in individual cells. Exp Cell Res. 175: 184-191.
Sinha, S., R. Saxena, and S. Singh. 2005. Chromium induced lipid peroxidation in the plants of Pistia stratiotes L.: role of antioxidants and antioxidant enzymes. Chemosphere. 58: 595-604.
Sugden, K.D.and K.E. Wetterhahn. 1997. Direct and hydrogen peroxide-induced chromium(V) oxidation of deoxyribose in single-stranded and double-stranded calf thymus DNA. Chem Res Toxicol. 10: 1397-1406.
Susa, N., S. Ueno, Y. Furukawa, N. Michiba, and S. Minoura. 1989. Induction of lipid peroxidation in mice by hexavalent chromium and its relation to the toxicity. Nippon Juigaku Zasshi. 51: 1103-1110.
Susin, S.A., E. Daugas, L. Ravagnan, K. Samejima, N. Zamzami, M. Loeffler, P. Costantini, K.F. Ferri, T. Irinopoulou, M.C. Prevost, G. Brothers, T.W. Mak, J. Penninger, W.C. Earnshaw, and G Kroemer. 2000. Two distinct pathways leading to nuclear apoptosis. J Exp Med. 192: 571-580.
Thomenius, M.J.and C.W. Distelhorst. 2003. Bcl-2 on the endoplasmic reticulum: protecting the mitochondria from a distance. J Cell Sci. 116: 4493-4499.
Travacio, M., J.M. Polo, and S. Llesuy. 2001. Chromium (VI) induces oxidative stress in the mouse brain. Toxicology. 162: 139-148.
van Gurp, M., N. Festjens G van Loo, X. Saelens, and P. Vandenabeele. 2003. Mitochondrial intermembrane proteins in cell death. Biochem Biophys Res Commun. 304: 487-497.
Wang, S., S.S. Leonard, J. Ye, M. Ding, and X. Shi. 2000. The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation. Am J Physiol Cell Physiol. 279: C868-875.
Wang, S., S.S. Leonard, J. Ye, N. Gao, L. Wang, and X. Shi. 2004. Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction. Mol Cell Biochem. 255: 119-127.
Wang, S.and X. Shi. 2001. Mechanisms of Cr(VI)-induced p53 activation: the role of phosphorylation, mdm2 and ERK. Carcinogenesis. 22:757-762.
Xu, J., F.C. Manning, and S.R. Patierno. 1994. Preferential formation and repair of chromium-induced DNA adducts and DNA-protein crosslinks in nuclear matrix DNA. Carcinogenesis. 15: 1443-1450.
Ye, J., S. Wang, S.S. Leonard, Y. Sun, L. Butterworth, J. Antonini, M. Ding, Y. Rojanasakul, V. Vallyathan, V. Castranova, and X. Shi. 1999. Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis. J Biol Chem. 274: 34974-34980.
Yu, J.and L. Zhang. 2005. The transcriptional targets of p53 in apoptosis control. Biochem Biophys Res Commun. 331:851-858.
Zhang, H., J. Heim, and B. Meyhack. 1998. Redistribution of Bax from cytosol to membranes is induced by apoptotic stimuli and is an early step in the apoptotic pathway. Biochem Biophys Res Commun. 251: 454-459.
Zhitkovich, A. 2005. Importance of chromium-DNA adducts in mutagenicity and toxicity of chromium(VI). Chem Res Toxicol. 18: 3-11.
Zhitkovich, A., G. Quievryn, J. Messer, and Z. Motylevich. 2002. Reductive activation with cysteine represents a chromium(HI)-dependent pathway in the induction of genotoxicity by carcinogenic chromium(VI). Environ Health Perspect. 110 Suppl 5: 729-731.
Zhitkovich, A., S. Shrager, and J. Messer. 2000. Reductive metabolism of Cr(VI) by cysteine leads to the formation of binary and ternary Cr-DNA adducts in the absence of oxidative DNA damage. Chem Res Toxicol. 13: 1114-1124.
Zhitkovich, A., Y. Song, G Quievryn, and V. Voitkun. 2001. Non-oxidative mechanisms are responsible for the induction of mutagenesis by reduction of Cr(VI) with cysteine: role of ternary DNA adducts in Cr(III)-dependent mutagenesis. Biochemistry. 40: 549-560.
Arakawa, H., R. Ahmad, M. Naoui, and H.A. Tajmir-Riahi. 2000. A comparative study of calf thymus DNA binding to Cr(III) and Cr(VI) ions. Evidence for the guanine N-7-chromium-phosphate chelate formation. J Biol Chem. 275: 10150-10153.
Bose, R.N., S. Moghaddas, P.A. Mazzer, L.P. Dudones, L. Joudah, and D. Stroup. 1999. Oxidative damage of DNA by chromium(V) complexes: relative importance of base versus sugar oxidation. Nucleic Acids Res. 27: 2219-2226.
Celander, D.W.and T.R. Cech. 1990. Iron(II)-ethylenediaminetetraacetic acid catalyzed cleavage of RNA and DNA oligonucleotides: similar reactivity toward single- and double-stranded forms. Biochemistry. 29: 1355-1361.
Costa, M. 2003. Potential hazards of hexavalent chromate in our drinking water. Toxicol Appl Pharmacol. 188: 1-5.
de la Sienra, E., M.A. Armienta, and M.E. Gonsebatt. 2003. Potassium dichromate increases the micronucleus frequency in the crayfish Procambarus clarkii. Environ Pollut. 126: 367-370.
Fornace, A.J., Jr., D.S. Seres, J.F. Lechner, and C.C. Harris. 1981. DNA-protein cross-linking by chromium salts. Chem Biol Interact. 36: 345-354.
Gajewski, E.and M. Dizdaroglu. 1990. Hydroxyl radical induced cross-linking of cytosine and tyrosine in nucleohistone. Biochemistry. 29: 977-980.
Ha, L., S. Ceryak, and S.R. Patierno. 2003. Chromium (VI) activates ataxia telangiectasia mutated (ATM) protein. Requirement of ATM for both apoptosis and recovery from terminal growth arrest. J Biol Chem. 278: 17885-17894.
Hamilton, J.W.and K.E. Wetterhahn. 1986. Chromium (VI)-induced DNA damage in chick embryo liver and blood cells in vivo. Carcinogenesis. 7: 2085-2088.
Hook, S.E.and R.F. Lee. 2004. Genotoxicant induced DNA damage and repair in early and late developmental stages of the grass shrimp Paleomonetes pugio embryo as measured by the comet assay. Aquat Toxicol. 66: 1-14.
Ito, K.and S. Kawanishi. 1997. Site-specific DNA damage induced by UVA radiation in the presence of endogenous photosensitizer. Biol Chem. 378: 1307-1312.
Izzotti, A., M. Bagnasco, A. Camoirano, M. Orlando, and S. De Flora. 1998. DNA fragmentation, DNA-protein crosslinks, postlabeled nucleotidic modifications, and 8-hydroxy-2'-deoxyguanosine in the lung but not in the liver of rats receiving intratracheal instillations of chromium(VI). Chemoprevention by oral N-acetylcysteine. Mutat Res. 400: 233-244.
Kawanishi, S., S. Inoue, and S. Sano. 1986. Mechanism of DNA cleavage induced by sodium chromate(VI) in the presence of hydrogen peroxide. J Biol Chem. 261: 5952-5958.
Koster, A.and D. Beyersmann. 1985. Chromium binding by calf thymus nuclei and effects on chromatin. Toxicol. Environ. Che. 10: 307-313.
Levina, A., P.A. Lay, and N.E. Dixon. 2001. Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro. Chem Res Toxicol. 14: 946-950.
Liu, K., J. Husler, J. Ye, S.S. Leonard, D. Cutler, F. Chen, S. Wang, Z. Zhang, M. Ding, L. Wang, and X. Shi. 2001. On the mechanism of Cr (VI)-induced carcinogenesis: dose dependence of uptake and cellular responses. Mol Cell Biochem. 222: 221-229.
O'Brien, T., H.G. Mandel, D.E. Pritchard, and S.R. Patierno. 2002a. Critical role of chromium (Cr)-DNA interactions in the formation of Cr-induced polymerase arresting lesions. Biochemistry. 41: 12529-12537.
O'Brien, T., J. Xu, and S.R. Patierno. 2001. Effects of glutathione on chromium-induced DNA crosslinking and DNA polymerase arrest. Mol Cell Biochem. 222: 173-182.
O'Brien, T.J., S. Ceryak, and S.R. Patierno. 2003. Complexities of chromium carcinogenesis: role of cellular response, repair and recovery mechanisms. Mutat Res. 533: 3-36.
O'Brien, T.J., J.L. Fornsaglio, S. Ceryak, and S.R. Patierno. 2002b. Effects of hexavalent chromium on the survival and cell cycle distribution of DNA repair-deficient S. cerevisiae. DNA Repair (Amst). 1: 617-627.
Pritchard, D.E., S. Ceryak, L. Ha, J.L. Fornsaglio, S.K. Hartman, T.J. O'Brien, and S.R. Patierno. 2001. Mechanism of apoptosis and determination of cellular fate in chromium(VI)-exposed populations of telomerase-immortalized human fibroblasts. Cell Growth Differ.-12: 487-496.
Quievryn, G., J. Messer, and A. Zhitkovich. 2002. Carcinogenic chromium(VI) induces cross-linking of vitamin C to DNA in vitro and in human lung A549 cells. Biochemistry. 41:3156-3167.
Quievryn, G., E. Peterson, J. Messer, and A. Zhitkovich. 2003. Genotoxicity and mutagenicity of chromium(VI)/ascorbate-generated DNA adducts in human and bacterial cells. Biochemistry. 42: 1062-1070.
Salnikow, K., A. Zhitkovich, and M. Costa. 1992. Analysis of the binding sites of chromium to DNA and protein in vitro and in intact cells. Carcinogenesis. 13: 2341-2346.
Snow, E.T.and L.S. Xu. 1991. Chromium(III) bound to DNA templates promotes increased polymerase processivity and decreased fidelity during replication in vitro. Biochemistry. 30: 11238-11245.
Strauss, J.K.and L.J. Maher, 3rd. 1994. DNA bending by asymmetric phosphate neutralization. Science. 266: 1829-1834.
Sugden, K.D., C.K. Campo, and B.D. Martin. 2001. Direct oxidation of guanine and 7,8-dihydro-8-oxoguanine in DNA by a high-valent chromium complex: a possible mechanism for chromate genotoxicity. Chem Res Toxicol. 14: 1315-1322.
Sugden, K.D.and B.D. Martin. 2002. Guanine and 7,8-dihydro-8-oxo-guanine-specific oxidation in DNA by chromium(V). Environ Health Perspect. 110 Suppl 5: 725-728.
Sugden, K.D.and K.E. Wetterhahn. 1997. Direct and hydrogen peroxide-induced chromium(V) oxidation of deoxyribose in single-stranded and double-stranded caif thymus DNA. Chem Res Toxicol. 10:1397-1406.
Tsou, T.C., H.J. Lai, and J.L. Yang. 1999. Effects of mannitol or catalase on the generation of reactive oxygen species leading to DNA damage by Chromium(VI) reduction with ascorbate. Chem Res Toxicol. 12: 1002-1009.
Ueno, S., T. Kashimoto, N. Susa, Y. Furukawa, M. Ishii, K. Yokoi, M. Yasuno, Y.F. Sasaki, J.
Ueda, Y. Nishimura, and M. Sugiyama. 2001. Detection of dichromate (Vl)-induced DNA strand breaks and formation of paramagnetic chromium in multiple mouse organs. Toxicol Appl Pharmacol. 170: 56-62.
Voitkun, V., A. Zhitkovich, and M. Costa. 1998. Cr(III)-mediated crosslinks of glutathione or amino acids to the DNA phosphate backbone are mutagenic in human cells. Nucleic Acids Res. 26: 2024-2030.
Xu, J., F.C. Manning, and S.R. Patierno. 1994. Preferential formation and repair of chromium-induced DNA adducts and DNA-protein crosslinks in nuclear matrix DNA. Carcinogenesis. 15: 1443-1450.
Zhitkovich, A., G. Quievryn, J. Messer, and Z. Motylevich. 2002. Reductive activation with cysteine represents a chromium(III)-dependent pathway in the induction of genotoxicity by carcinogenic chromium(VI). Environ Health Perspect. 110 Suppl 5: 729-731.
Zhitkovich, A., S. Shrager, and J. Messer. 2000. Reductive metabolism of Cr(VI) by cysteine leads to the formation of binary and ternary Cr-DNA adducts in the absence of oxidative DNA damage. Chem Res Toxicol. 13:1114-1124.
Zhitkovich, A., Y. Song, G. Quievryn, and V. Voitkun. 2001. Non-oxidative mechanisms are responsible for the induction of mutagenesis by reduction of Cr(VI) with cysteine: role of ternary DNA adducts in Cr(III)-dependent mutagenesis. Biochemistry. 40: 549-560.
Zhitkovich, A., V. Voitkun, and M. Costa. 1995. Glutathione and free amino acids form stable complexes with DNA following exposure of intact mammalian cells to chromate. Carcinogenesis. 16: 907-913.
Zhitkovich, A.. V. Voitkun, and M. Costa. 1996. Formation of the amino acid-DNA complexes by hexavalent and trivalent chromium in vitro: importance of trivalent chromium and the phosphate group. Biochemistry. 35: 7275-7282.
Zhitkovich, A., V. Voitkun, T. Kluz, and M. Costa. 1998. Utilization of DNA-protein cross-links as a biomarker of chromium exposure. Environ Health Perspect. 106 Suppl 4: 969-974.
全晓塞，王淑华，尚国平，等．2003．饮用水二次污染研究(Ⅰ)—末梢水水质与二次污染．宁夏工程技术，2(4)：337-339．
王晓峰，楼建林，邢鸣鸾，连灵君，徐立红．六价铬致小鼠DNA损伤及肝肾氧化应激的实验研究．环境科学学报，2006，26(11)：1860-1864
王晓峰，傅文宇，朱欣，徐立红．六价铬对大鼠肝细胞体外的毒作用．癌变．畸变．突变，2005，17(6)：343-345
王晓峰，徐立红．Cr(Ⅵ)化合物引起DNA损伤的机制．环境与健康杂志，2006，23(1)：93-96
Anuradha, C.D., S. Kanno, and S. Hirano. 2001. Oxidative damage to mitochondria is a preliminary step to caspase-3 activation in fluoride-induced apoptosis in HL-60 cells. Free Radic Biol Med. 31: 367-373.
Arakawa, H., F. Wu, M. Costa, W. Rom, and M.S. Tang. 2006. Sequence specificity of Cr(Ⅲ)-DNA adduct formation in the p53 gene: NGG sequences are preferential adduct-forming sites. Carcinogenesis. 27: 639-645.
Bagchi, D., J. Balmoori, M. Bagchi, X. Ye, C.B. Williams, and S.J. Stohs. 2000. Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (Ⅵ) in liver and brain tissues of mice. Free Radic Biol Med. 28: 895-903.
Bagchi, D., S.J. Stohs, B.W. Downs, M. Bagchi, and H.G. Preuss. 2002. Cytotoxicity and oxidative mechanisms of different forms of chromium. Toxicology. 180: 5-22.
Banin, S.,L. Moyal, S. Shieh, Y. Taya, C.W. Anderson, L. Chessa, N.I. Smorodinsky, C. Prives, Y. Reiss, Y. Shiloh, and Y. Ziv. 1998. Enhanced phosphorylation of p53 by ATM in response to DNA damage. Science. 281: 1674-1677.
Brady, H.J.and G. Gil-Gomez. 1998. Bax. The pro-apoptotic Bcl-2 family member, Bax. Int J Biochem Cell Biol. 30: 647-650.
Carlisle, D.L., D.E. Pritchard, J. Singh, B.M. Owens, L.J. Blankenship, J.M. Orenstein, and S.R. Patierno. 2000a. Apoptosis and P53 induction in human lung fibroblasts exposed to chromium (Ⅵ): effect of ascorbate and tocopherol. Toxicol Sci. 55: 60-68.
Carlisle, D.L., D.E. Pritchard, J. Singh, and S.R. Patierno. 2000b. Chromium(Ⅵ) induces p53-dependent apoptosis in diploid human lung and mouse dermal fibroblasts. Mol Carcinog. 28:111-118.
Ceryak, S., C. Zingariello, T. O'Brien, and S.R. Patierno. 2004. Induction of pro-apoptotic and cell cycle-inhibiting genes in chromium (VI)-treated human lung fibroblasts: lack of effect of ERK. Mol Cell Biochem. 255: 139-149.
Ding, M.and X. Shi. 2002. Molecular mechanisms of Cr(VI)-induced carcinogenesis. Mol Cell Biochem. 234-235: 293-300.
Donald, S.P., X.Y. Sun, C.A. Hu, J. Yu, J.M. Mei, D. Valle, and J.M. Phang. 2001. Proline oxidase, encoded by p53-induced gene-6, catalyzes the generation of proline-dependent reactive oxygen species. Cancer Res. 61: 1810-1815.
Feng, Z., W. Hu, W.N. Rom, M. Costa, and M.S. Tang. 2003. Chromium(VI) exposure enhances polycyclic aromatic hydrocarbon-DNA binding at the p53 gene in human lung cells. Carcinogenesis. 24: 771-778.
Foo, S.Y.and GP. Nolan. 1999. NF-kappaB to the rescue: RELs, apoptosis and cellular transformation. Trends Genet. 15: 229-235.
Gambelunghe, A., R. Piccinini, G. Abbritti, M. Ambrogi, B. Ugolini, C. Marchetti, G Migliorati, C. Balducci, and G Muzi. 2006. Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4). J Occup Environ Med. 48: 319-325.
Gunaratnam, M.and M.H. Grant. 2002. Chromium(VI)-induced damage to the cytoskeleton and cell death in isolated hepatocytes. Biochem Soc Trans. 30: 748-750.
Ha, L., S. Ceryak, and S.R. Patierno. 2003. Chromium (VI) activates ataxia telangiectasia mutated (ATM) protein. Requirement of ATM for both apoptosis and recovery from terminal growth arrest. J Biol Chem. 278: 17885-17894.
Haupt, Y., A.I. Robles, C. Prives, and V. Rotter. 2002. Deconstruction of p53 functions and regulation. Oncogene. 21: 8223-8231.
Hayashi, Y., T. Kondo, Q.L. Zhao, R. Ogawa, Z.G Cui, L.B. Feril, Jr., H. Teranishi, and M. Kasuya. 2004. Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells. Toxicol Appl Pharmacol. 197: 96-106.
lzzotti, A., M. Bagnasco, C. Cartiglia, M. Longobardi, and S. De Flora. 2004. Proteomic analysis as related to transcriptome data in the lung of chromium(Ⅵ)-treated rats. Int J Oncol. 24: 1513-1522.
Khosravi, R., R. Maya, T. Gottlieb, M. Oren, Y. Shiloh, and D. Shkedy. 1999. Rapid ATM-dependent phosphorylation of MDM2 precedes p53 accumulation in response to DNA damage. Proc Natl Acad Sci U S A. 96: 14973-14977.
Matsuoka, S., G. Rotman, A. Ogawa, Y. Shiloh, K. Tamai, and S.J. Elledge. 2000. Ataxia telangiectasia-mutated phosphorylates Chk2 in vivo and in vitro. Proc Natl Acad Sci U S A. 97: 10389-10394.
Norbury, C.J.and B. Zhivotovsky. 2004. DNA damage-induced apoptosis. Oncogene. 23:2797-2808.
Polyak, K., Y. Xia, J.L. Zweier, K.W. Kinzler, and B. Vogelstein. 1997. A model for p53-induced apoptosis. Nature. 389: 300-305.
Pritchard, D.E., J. Singh, D.L. Carlisle, and S.R. Patierno. 2000. Cyclosporin A inhibits chromium(Ⅵ)-induced apoptosis and mitochondrial cytochrome c release and restores clonogenic survival in CHO cells. Carcinogenesis. 21: 2027-2033.
Rudolf, E.and M. Cervinka. 2006. The role of intracellular zinc in chromium(Ⅵ)-induced oxidative stress, DNA damage and apoptosis. Chem Biol Interact. 162: 212-227.
Rudolf, E., M. Cervinka, J. Cerman, and L. Schroterova. 2005. Hexavalent chromium disrupts the actin cytoskeleton and induces mitochondria-dependent apoptosis in human dermal fibroblasts. Toxicol In Vitro. 19: 713-723.
Russo, P., A. Catassi, A. Cesario, A. Imperatori, N. Rotolo, M. Fini, P. Granone, and L. Dominioni. 2005. Molecular mechanisms of hexavalent chromium-induced apoptosis in human bronchoalveolar cells. Am J Respir Cell Mol Biol. 33: 589-600.
Shimada, H., Y.H. Shiao, M. Shibata, and M.P. Waalkes. 1998. Cadmium suppresses apoptosis induced by chromium. J Toxicol Environ Health A. 54: 159-168.
Wang, S., F. Chen, Z. Zhang, B.H. Jiang, L. Jia, and X. Shi. 2004a. NF-kappaB prevents cells from undergoing Cr(VI)-induced apoptosis. Mol Cell Biochem. 255: 129-137.
Wang, S., S.S. Leonard, J. Ye, M. Ding, and X. Shi. 2000. The role of hydroxyl radical as a messenger in Cr(VI)-induced p53 activation. Am J Physiol Cell Physiol. 279: C868-875.
Wang, S., S.S. Leonard, J. Ye, N. Gao, L. Wang, and X. Shi. 2004b. Role of reactive oxygen species and Cr(VI) in Ras-mediated signal transduction. Mol Cell Biochem. 255: 119-127.
Wang, S.and X. Shi. 2001. Mechanisms of Cr(VI)-induced p53 activation: the role of phosphorylation, mdm2 and ERK. Carcinogenesis. 22: 757-762.
Ye, J.and X. Shi. 2001. Gene expression profile in response to chromium-induced cell stress in A549 cells. Mol Cell Biochem. 222: 189-197.
Ye, J., S. Wang, S.S. Leonard, Y. Sun, L. Butterworth, J. Antonini, M. Ding, Y. Rojanasakul, V. Vallyathan, V. Castranova, and X. Shi. 1999. Role of reactive oxygen species and p53 in chromium(VI)-induced apoptosis. J Biol Chem. 274: 34974-34980.
Yu, J.and L. Zhang. 2005. The transcriptional targets of p53 in apoptosis control. Biochem Biophys Res Commun. 331: 851-858.
Zhang, H., J. Heim, and B. Meyhack. 1998. Redistribution of Bax from cytosol to membranes is induced by apoptotic stimuli and is an early step in the apoptotic pathway. Biochem Biophys Res Commun. 251:454-459.