Studies on effects of vinorelbine plus radiation on human breast cancer cell line MCF-7

Objective: To investigate the mechanism of the anticancer action of vinorelbine combined with radiation on human breast cancer cell line MCF-7. Methods: The MTT method was applied to examine the growth inhibition of MCF-7 treated with vinorelbine. The cell cycle distribution and apoptosis index (AI) were analysed by flow cytometry. The morphology of the MCF-7 cells apoptosis was observed by transmission electron microscopy. Results: The MTT result showed the IC50 of vinorelbine for 24 h was 7.20 μg/ml. Cell cycle analysis showed the four groups have the different cell cycle distribution. In control group, many cells were in the G1-S phase; in vinorelbine group, the percentage of the cell population in G2/M was significantly different from that of control group or radiation group (P<0.05). The apoptotic indexes (AI) of MCF-7 of four groups showed: The mean AI at different time of radiation group, vinorelbine group and vinorelbine plus radiation group were 2.98 +- 3.90%, 8.01 +- 1.87%, 15.57 +- 5.23%, the AI of (V+R) group was significantly different from that in the vinorelbine group or radiation group (P<0.05). Transmission electronic microscope can detect condensed chromatin, nuclear fragmentation and apoptotic body of MCF-7 cells. Conclusion: Vinorelbine can inhibit the growth of human breast cancer cell line MCF-7. It can cause accumulation of MCF-7 cells in the G2/M phase of the cell cycle, and can induce its apoptosis. Vinorelbine pretreatment before radiation can potentiate the effects of radiation and apoptosis induced by radiation