Host: The Japan Radiation Research Society, Chairman of the 52nd Annual Meeting, Toshiteru Okubo (Radiation Effects Research Foundation)
Anticancer agents induce DNA lesions such as DNA-protein crosslinks (DPCs), interstrand and intrastrand crosslinks (ICLs), double strand breaks (DSBs), and base modifications to various degrees. DPCs, ICLs, and DSBs block DNA replication and hence exert strong lethal effects on cells. However, it has not been fully elucidated to what extent individual DNA lesions contribute to cell death upon treatment with anticancer agents. To clarify this, we analyzed the relationship between the cell-killing efficacies of anticancer agents and the yields of DPCs, ICLs, and DSBs formed in treated cells. HeLa cells were incubated with different types of anticancer agents including alkylating agents [mitomycin C (MMC) and melphalan (L-PAM)], platinum compounds [cisplatin (cis-Pt) and oxaliplatin (L-OHP)], a DNA methylase inhibitor [5-aza-2'-cytidine (azadC)], and topoisomerase inhibitors [camptothecin (CPT) and etoposide (VP-16)]. The lethal effects of anticancer agents were analyzed by colony formation. The doses that gave 10% cell survival were L-PAM (4.23 μM), L-OHP (1.5 μM), azadC (1.35 μM), cis-Pt (0.68 μM), VP-16 (0.43 μM), MMC (0.025 μM), and CPT (0.0076 μM). To quantify DNA damage, cells were treated with these doses of anticancer agents, and genomic DNA was isolated and purified by CsCl density gradient ultracentrifugation. We established a Western blotting method for highly sensitive detection of DPCs and are currently analyzing DPCs. We will also quantify ICLs and DSBs produced by individual anticancer agents. The results will be presented in the meeting.
