Increased Cdc7 expression is a marker of oral squamous cell carcinoma and overexpression of Cdc7 contributes to the resistance to DNA-damaging agents

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• 作者：An Ning Cheng ; Shih Sheng Jiang ; Chi-Chen Fan ; Yu-Kang Lo ; Chan-Yen Kuo ; Chung-Hsing Chen ; Ying-Lan Liu ; Chun-Chung Lee ; Wei-Shone Chen ; Tze-Sing Huang ; Tao-Yeuan Wang ; Alan Yueh-Luen Lee
• 关键词：DDK ; Dbf4-dependent kinase ; DDR ; DNA damage response ; OSCC ; oral squamous cell carcinoma ; IHC ; immunohistochemistry ; HU ; hydroxyurea ; CPT ; camptothecin ; CI ; confidence interval ; HR ; hazard ratios ; TUNEL ; terminal deoxynucleotidyl transferase-mediated dUTP
• 刊名：Cancer Letters
• 出版年：2013
• 出版时间：1 September, 2013
• 年：2013
• 卷：337
• 期：2
• 页码：218-225
• 全文大小：2035 K

文摘

Cdc7-Dbf4 kinase (Dbf4-dependent kinase, DDK) is an essential factor of DNA replication and DNA damage response (DDR), which is associated with tumorigenesis. However, Cdc7 expression has never been associated to the outcome of oral squamous cell carcinoma (OSCC) patients, and the mechanism underlying cancer cell survival mediated by Cdc7 remains unclear. The Cdc7 protein expression of 105 OSCC tumor and 30 benign tissues was examined by immunohistochemistry assay. Overall survival rates of 80 OSCC patients were measured using Kaplan-Meier estimates and the log-rank tests. Cdc7 overexpression by adenovirus system was used to scrutinize the underlying mechanism contributed to cancer cell survival upon DDR. In silico analysis showed that increased Cdc7 is a common feature of cancer. Cdc7 overexpression was found in 96 of 105 (91.4 % ) studied cases of OSCC patients. Patients with higher Cdc7 expression, either categorized into two groups: Cdc7 high expression (2+ to 3+) versus Cdc7 low expression (0 to 1+) [hazard ratios (HR) = 2.6; 95 % confidence interval (CI) = 1.28-5.43; P = 0.0087] or four groups (0 to 3+) [HR = 1.71; 95 % CI = 1.20-2.44; P = 0.0032], exhibited a poorer outcome. Multivariate analysis showed that Cdc7 is an independent marker for survival prediction. Overexpressed Cdc7 inhibits genotoxin-induced apoptosis to increase the survival of cancer cells. In summary, Cdc7 expression, which is universally upregulated in cancer, is an independent prognostic marker of OSCC. Cdc7 inhibits genotoxin-induced apoptosis and increases survival in cancer cells upon DDR, suggesting that high expression of Cdc7 enhances the resistance to chemotherapy.