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

Eriko Takatori,1 Tadahiro Shoji,1 Takashi Sawai,2 Akira Kurose,3 Toru Sugiyama11Department of Obstetrics and Gynecology, 2Department of Pathology, Iwate Medical University, Morioka, Japan; 3Department of Anatomic Pathology, Hirosaki University, Hirosaki, JapanBackground: 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 γH2AX.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-γH2AX antibody. γH2AX and nuclear DNA were then simultaneously detected by flow cytometry using fluorescein isothiocyanate and propidium iodide, respectively, to determine the amounts of γH2AX 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 G2/M phases, and increased apoptosis. Similarly, with CBDCA, OVISE showed S- and G2/M-phase arrest, while RMG-I showed G2/M-phase arrest.Conclusion: The mechanism of action of GEM and CBDCA in CCC cell lines was elucidated using γH2AX as a DNA damage marker. Our findings suggested that concomitant use of GEM plus CBDCA may be effective in the treatment of CCC.Keywords: γH2AX, clear-cell carcinoma, ovarian cancer, DNA damage, apoptosis, gemcitabine, carboplatin