Targeting Chk2 improves gastric cancer chemotherapy by impairing DNA damage repair

Abstract

Our results demonstrate that the addition of cisplatin after paclitaxel-induced mitotic arrest was more effective than individual treatment on gastric adenocarci noma cells (MKN45). However, the treatment did not induce benefits in cells derived from lymph node metas tasis (ST2957). Time-lapse microscopy revealed that cell death was caused by mitotic catastrophe and apoptosis induction, as the use of the caspase inhibitor z-VAD-fmk decreased cell death. We propose that the molecular mechanism mediating this cell fate is a slippage suffered by these cells, given that our Western blot (WB) analysis revealed premature cyclin B degradation. This resulted in the cell exiting from mitosis without undergoing DNA damage repair, as demonstrated by the strong phosphory lation of H2AX. A comet assay indicated that DNA repair was impaired, and Western blotting showed that the Chk2 protein was degraded after sequential treatment (paclitaxel cisplatin). Based on these results, the modulation of cell death during mitosis may be an effective strategy for gas tric cancer therapy. Keywords Cancer ! Mitosis ! Cisplatin ! DNA damage response