ATM is required for the repair of Topotecan-induced replication-associated double-strand breaks

作者：Koecher Sabrina; Spies Naumann Anja; Kriegs Malte; Dahm Daphi Jochen; Dornreiter Irena

来源：Radiotherapy and Oncology, 2013, 108(3): 409-414.

DOI：10.1016/j.radonc.2013.06.024

• ATM
• Topotecan
• Homology-directed repair
• Replication-associated DSBs
• SKX

Purpose: DNA replication is a promising target for anti-cancer therapies. Therefore, the understanding of replication-associated DNA repair mechanisms is of great interest. One key factor of DNA double-strand break (DSB) repair is the PIK kinase Ataxia-Telangiectasia Mutated (ATM) but it is still unclear whether ATM is involved in the repair of replication-associated DSBs. Here, we focused on the involvement of ATM in homology-directed repair (HDR) of indirect DSBs associated with replication. %26lt;br%26gt;Material and methods: Experiments were performed using ATM-deficient and -proficient human cells. Replication-associated DSBs were induced with Topotecan (TPT) and compared with gamma-irradiation (IR). Cell survival was measured by clonogenic assay. Overall DSB repair and HDR were evaluated by detecting residual gamma H2AX/53BP1 and Rad51 foci, respectively. Cell cycle distribution was analysed by flow cytometry and protein expression by Western blot. %26lt;br%26gt;Results: ATM-deficiency leads to enhanced numbers of residual DSBs, resulting in a pronounced S/G2-block and decreased survival upon TPT-treatment. In common with IR, persisting Rad51 foci were detected following TPT-treatment. %26lt;br%26gt;Conclusions: These results demonstrate that ATM is essentially required for the completion of HR-mediated repair of TPT-induced DSBs formed indirectly at replication forks.

• 出版日期2013-9