Studies Of Vinorelbine Plus Radiation On Human Breast Cancer Cell Line MCF-7

Objective: To investigate cell proliferation inhibition, cell cycle distribution and cell apoptosis of human breast cancer cell line MCF-7 treated with vinorelbine alone and combinated with radiation in vitro, in order to demonstrate the mechanism of the anticancer action of vinorelbine alone and combinated with radiation.Methods: The MTT methods was applied to examine the growth inhibition of human breast cancer cell line MCF-7 treated with vinorelbine, and choose the dose of vinorelbine to use. the cells were divided into four groups in random: control group(C),radiation group(R), vinorelbine group(V) and vinorelbine plus radiation group(V+R). the cell cycle distribution and apoptosis index(AI) were analysed by Flow Cytometry. the morphology of the MCF-7 cells apoptosis were observed by transmission electron microscopy. Results: The MTT results showed vinorelbine could significantly inhibited growth proliferation of MCF-7 cells when the cells were exposed to vinorelbine at 1,2,4,8,12ug/ml for 24h. Inhibition rate was 21.40+ 1. 96%, 25. 80 ± 0. 40%, 31. 00 ± 1. 41%, 53. 20 + 1. 47%, 77. 10 ± 1.53%,respectively, and it was in a dose dependent manner.The IC50 for 24h was 7. 20ug/ml.Cell cycle analysis showed the four groups have the different cell cycle distribution. In control group, many cells were in the Gl-S phase, some cells were in the G2 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). In vinorelbine plus radiation group, the percentage of the cell population in Gl was significantly lower than that of control group (P=0. 001) ; and the percentage of the cell population in G2 was significantly higher than that of control group (P<0.05).The apoptotic indexes (AI) of MCF-7 of four groups showed: control group has the very low AI; radiation group has apoptosis when the cells were radiated for 48 hours; the AI of vonorelbine group for 12h, 24h, 48h were 5. 67 + 0. 24%, 10. 05 +0.75% and 8. 32 ±0. 42%. vinorelbine plus radiation group has significant apoptosis when for 12h, the AI of (V+R) group for 12h, 24h,48h were 22. 40± 2. 70%, 12. 95± 1. 85% and 11.35 ±0.05%. The mean AI in 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 of vinorelbine group or radiation group (P<0. 05).Transmission electronmicroscope can detect condensed chromatin,nuclear fragmentation and apoptotic body of MCF-7 cell. Conclusions: 1.Vinorelbine can inhibit the growth of human breast cancer cell line MCF-7. 2.Vinorelbine can cause accumulation of MCF-7 cells in the G2/M phase of the cell cycle, and can induce its apoptosis. 3. Radiation can induce apoptosis of MCF-7. 4.Vinorelbine pretreatment before radiation can potentiate the effects of radiation and apoptosis induced by radiation and vinorelbine.