Impairment of APE1 function enhances cellular sensitivity to clinically relevant alkylators and antimetabolites.
Impairment of APE1 function enhances cellular sensitivity to clinically relevant alkylators and antimetabolites.
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DOI：
10.1158/1541-7786.mcr-08-0519
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发表时间：
2009-06
期刊：
影响因子：
--
通讯作者：
Wilson DM 3rd
中科院分区：
文献类型：
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作者：
McNeill DR;Lam W;DeWeese TL;Cheng YC;Wilson DM 3rd
Base excision repair (BER) is the major pathway for removing mutagenic and cytotoxic oxidative and alkylation DNA modifications. Using a catalytically-inactive, dominant negative protein form of human APE1, termed ED, which binds with high affinity to substrate DNA and blocks subsequent repair steps, we assessed the role of BER in mediating cellular resistance to clinically relevant alkylating drugs and antimetabolites. Colony formation assays revealed that ED expression enhanced cellular sensitivity to melphalan not at all; to decarbazine, thiotepa, busulfan and carmustine moderately (1.2 to 2.4-fold); and to streptozotocin and temozolomide significantly (2.0 to 5.3-fold). The effectiveness of ED to promote enhanced cytotoxicity generally correlated with the agent's (i) monofunctional nature, (ii) capacity to induce N7-guanine and N3-adenine modifications, and (iii) inability to generate O6-guanine adducts or DNA crosslinks. ED also enhanced the cell killing potency of the antimetabolite troxacitabine, apparently by blocking the processing of DNA strand breaks, yet had no effect on the cytotoxicity of gemcitabine, results that agree well with the known efficiency of APE1 to excise these nucleoside analogs from DNA. Most impressively, ED expression produced an ∼5- and 25-fold augmentation of the cell killing effect of 5-fluorouracil (5-FU) and 5-fluorodeoxyuridine, respectively, implicating BER in the cellular response to such antimetabolites; the increased 5-FU sensitivity was associated with an accumulation of abasic sites and active caspase positive staining. Our data suggest that APE1, and BER more broadly, is a potential target for inactivation in anti-cancer treatment paradigms that involve select alkylating agents or antimetabolites.
