Objective:The aim of the study was to evaluate the inhibition of different chemotherapy drugs on γ-synuclein (SNCG) positive expression of breast cancer cell line MDA-MB231,and the effects on cell cycle and apoptosis,and to explore the related mechanism as well.Methods:We treated the breast cancer cell line MDA-MB231 for the inhibition of SNCG with chemotherapy drugs such as irinotecan,nedaplatin and 5-fluorouracil using RT-PCR and immunohistochemistry,and adopted flow cytometry to detect cell cycle distribution and apoptosis.Results:At the transcription and translation levels,the SNCG expression level in nedaplatin group and 5-fluorouracil group was lower than that of other groups and there was statistically significance (P < 0.01) compared with the control group,while there was not statistically significant between irinotecan group and the control group.After drugs action,cell cycle and distribution in each experiment group changed obviously,where the cells in G0G1 phase increased,especially the cells in the nedaplatin group and 5-fluorouracil group changed most significantly,as well as the obvious change in the cells of nedaplatin group and 5-fluorouracil group in the apoptosis period.Conclusion:There was a stronger inhibition of SNCG expression in nedaplatin and 5-fluorouracil groups,and can cause significant cell cycle and apoptosis changes.It may also be concluded that nedaplatin and 5-fluorouracil could make effects by the mechanisms of inhibiting cancer cell proliferation and inducing cell apoptosis. Objective: The aim of the study was to evaluate the inhibition of different chemotherapy drugs on γ-synuclein (SNCG) positive expression of breast cancer cell line MDA-MB231, and the effects on cell cycle and apoptosis, and to explore the related mechanism as well. Methods: We treated the breast cancer cell line MDA-MB231 for the inhibition of SNCG with chemotherapy drugs such as irinotecan, nedaplatin and 5-fluorouracil using RT-PCR and immunohistochemistry, and flow cytometry to detect cell cycle distribution and apoptosis. Results: At the transcription and translation levels, the SNCG expression level in nedaplatin group and 5-fluorouracil group was lower than that of other groups and there was Bian significance (P <0.01) compared with the control group, while there was not significant event between irinotecan group and the control group. After the drug action, cell cycle and distribution in each experiment group changed obviously, where the cells in G0G1 phase increased, e specially the cells in the nedaplatin group and 5-fluorouracil group changed most significantly, as well as the obvious change in the cells of nedaplatin group and 5-fluorouracil group in the apoptosis period. Confc: There was a stronger inhibition of SNCG expression in nedaplatin and 5-fluorouracil groups, and can cause significant cell cycle and apoptosis changes. It may also be concluded that nedaplatin and 5-fluorouracil could make effects by the mechanisms of inhibiting cancer cell proliferation and inducing cell apoptosis.