A comparative molecular analysis of DNA damage response, cell cycle progression, viability and apoptosis of malignant granulosa cells exposed to gemcitabine and cisplatin

Abstract

We aimed to provide a comparative characterization of DNA damage response elements, survival/apoptosis and cell cycle progression of the malignant granulosa cells exposed to gemcitabine and cisplatin. Malignant granulosa tumor cell lines COV434 and KGN were used for the experiments. Cell viability, proliferation, DNA damage response and apoptosis were investigated. Cell cycle progression was assessed. In vitro estradiol (E-2) and AMH productions of the cells were measured. Exposure of asynchronous malignant granulosa cells to gemcitabine caused growth arrest, induced DNA damage and activated cellular stress pathways, cell cycle checkpoint sensors and triggered apoptosis as evidenced by increased expression of phospho-p38, gamma-histone H2AX, phospho-Chk-1/phospho-Chk-2, and cleaved forms of PARP and caspase-3 in a dose dependent manner. In vitro E-2 and AMH productions of the cells were decreased along with reduction in viable cell mass. Cisplatin treatment produced a similar response but it was associated with JNK activation rather than p38. When the cells were synchronized and treated with gemcitabine at G(2)/M transition, the degradation of cyclin B1 and dephosphorylation of cdc-2 at Tyr 15 residue did not occur, resulting in cycle arrest. Similar effects on cell cycle progression was also observed in cisplatin. However, it was associated with JNK activation and higher expression of gamma-histone H2AX and cleaved forms of caspase-3 and PARP, indicative of more extensive DNA damage and apoptosis in the cells. This descriptive study provides evidence that gemcitabine exerts cytotoxic effects and causes perturbations in cell cycle progression of malignant granulosa cells.