[Study of ceramide monohexoside in ovarian cell line COC1/DDP resistant to cisplantin].

OBJECTIVE: To investigate the effect of ceramide monohexoside (CMH) on resistance to cisplatin and apoptosis in ovarian cell line COC1/DDP, and to provide new ideals and clues to seek new effective methods for studying the mechanism and reversing the resistance in ovarian cell line as well.

METHODS: COC1 cells and COC1/DDP cells (before and after the treatment of mifepristone) were collected and neutral glycosphingolipids (N-GSLs) of the cells was isolated and purified, changes of CMH content were analyzed by high performance thin layer chromatography (HPTLC). The COC1/DDP cells were divided into three groups, one treated by cisplatin, one treated by mifepristone, the other treated by cisplatin and mifepristone. The survival rate of cells in three groups were evaluated by the methyl thiazolyl tetrazolium (MTT) assay, DNA ladders were presented by DNA gel electrophoresis, the forms of cells were observed by transmission electron microscope (TEM).

RESULTS: The levels of CMH were (37.1 +/- 3.3)% in COC1/DDP, higher than that in COC1 (14.1 +/- 1.4)% (P < 0.001). After treating by 1.25, 5 micro mol/L mifepristone, the CMH were (26.6 +/- 2.6)% (P < 0.05) and (17.5 +/- 0.7)% (P < 0.001), respectively. Mifepristone had no effect on the viability of COC1/DDP cell below a concentration of 5 micro mol/L. But when mifepristone of 1.25 or 5 micro mol/L combined with cisplatin at a concentration of 0.1, 0.25, 0.5, 1.25, 2.5 micro g/ml, the inhibition rate of COC1/DDP cell is higher than that of COC1/DDP cells only treated by cisplatin at the concentration of 0.1 to 2.5 micro g/ml (P < 0.001). The combined treatment elicited DNA fragmentation, however, neither cisplatin of 1.25 micro g/ml nor mifepristone of 5 micro mol/L alone could potentiate DNA fragmentation. After the combined treatment, the COC1/DDP cells produced apoptosis body.

CONCLUSIONS: CMH is related with resistance to cisplantin in ovarian cell line COC1/DDP. When CMH of COC1/DDP cells was inhibited by mifepristone, the cells were sensitive to cisplatin and apoptosis was elicited.