Induction of cytochromes P450, caspase-3 and DNA damage by PCB3 and its hydroxylated metabolites in porcine ovary
- 作者：Anna Ptak ; Gabriele Ludewig ; Maria Kapiszewska ; Zofia Magnowska ; Hans-Joachim Lehmler ; Larry W. Robertson and Ewa L. Gregoraszczuk
- 关键词：PCB3 ; Hydroxylated metabolites ; Prepubertal pig ovary ; CYP ; DNA damage ; Caspase-3 activity
- 刊名：Toxicology Letters
- 出版年：2006
- 期刊代码：49_03784274
- 类别：pha
- 出版时间：25 October 2006
- 卷：166
- 期：3
- 页码：200-211
- 文件大小：408 K
摘要
Polychlorinated biphenyl (PCBs) levels of tens and hundreds of pg/ml for individual congeners are measured in human follicular fluid. PCB3 (4-chlorobiphenyl), caused a significant increase in estradiol secretion in porcine granulose–theca cell co-cultures and its two metabolites, 4-OH-PCB3 and 3,4-diOH-PCB3, were even more potent than PCB3 itself [Ptak, A., Ludewig, G., Lehmler, H.J., Wojtowicz, A.K., Robertson, L.W., Gregoraszczuk, E.L. 2005. Comparison of the actions of 4-chlorobiphenyl and its hydroxylated metabolites on estradiol secretion by ovarian follicles in primary cells in culture. Reprod. Toxicol. 20, 57–64]. The question is whether these follicle cells are potentially able to metabolize PCB3 to hydroxylated and genotoxic or cytotoxic intermediates. We report here that granulose–theca co-cultures express xenobiotic-metabolizing cytochrome P450 activities, with CYP1A1 > CYP2B CYP1A2. A significant increase in CYP1A1 and 2B, but not CYP1A2, activity was seen in cells that were exposed to 6 ng/ml PCB3 or 20 nM 17-β-estradiol. An increase in caspase-3 activity, indicative for apoptosis, was only observed in PCB3-exposed cells after 24 h exposure. Genotoxicity, determined with the Comet assay, was initially reduced after 24 h exposure to PCB3 and both metabolites compared to untreated controls, followed by a significant transient increase in Comets at the 4 and 24 h time point with PCB3 and 4-OH-PCB3. 3,4-diOH-PCB3 induced a significant increase only after 72 h of recovery. We hypothesize that these biphasic damage kinetics may be due to cross-links caused by adduct formation. These results show for the first time that granulose–theca cells in co-culture express CYP1A1, 2B and 1A2 activities and that PCBs at concentrations that are reached in the environment induce genotoxicity in granulosa cells.