Analysis of the antitumor activity of gemcitabine and carboplatin against ovarian clear-cell carcinoma using the DNA damage marker γH2AX

Background: Differences in the incidence and type of DNA damage induced by antitumor agents for ovarian clear-cell carcinoma (CCC) were determined in two CCC cell lines, using gamma H2AX. Materials and methods: The antitumor activity of gemcitabine (GEM) and carboplatin (CBDCA) were examined using cultured cell lines of CCC (OVISE and RMG-I). Each cell line was treated with GEM and CBDCA, the cells were collected, fixed, and then reacted with anti-gamma H2AX antibody.gamma H2AX and nuclear DNA were then simultaneously detected by flow cytometry using fluorescein isothiocyanate and propidium iodide, respectively, to determine the amounts of gamma H2AX formed in each cell-cycle phase. Results: After administration of GEM, both cell lines showed DNA damage and cell-cycle arrest in the S and G(2)/M phases, and increased apoptosis. Similarly, with CBDCA, OVISE showed S-and G(2)/M-phase arrest, while RMG-I showed G(2)/M-phase arrest. Conclusion: The mechanism of action of GEM and CBDCA in CCC cell lines was elucidated using gamma H2AX as a DNA damage marker. Our findings suggested that concomitant use of GEM plus CBDCA may be effective in the treatment of CCC.