Study on the proliferation and apoptosis characteristics of polyploid non-small cell lung cancer A549 cells induced by docetaxel / 肿瘤研究与临床

ABSTRACT

Objective:To investigate the proliferation and apoptosis characteristics of polyploid non-small cell lung cancer (NSCLC) cell model induced by docetaxel (Doc), and to analyze the potential role of polyploid tumor cells in chemotherapy resistance and tumor recurrence.Methods:NSCLC A549 cells were treated with dimethyl sulfoxide (DMSO) or 1 μmol/L Doc for 24 h. After drug removal, the cells were cultured in complete medium until the third day or the 5th day, and then they were recorded as the control group, Doc 24 h group, Doc 24 h+ 3 d group, Doc 24 h + 5 d group, respectively. The cell morphology was detected by using immunofluorescence staining. Flow cytometry was used to determine cell ploidy and cell cycle. Dil labeling and CFSE labeling were applied to detect cell proliferation. Flow cytometry by Annexin-V/PI double labeling was used to detect apoptosis. The changes of cyclin and apoptotic protein were analyzed by using Western blot.Results:Immunofluorescence staining results showed that compared with the control group, the volume of a small number of surviving cells in Doc 24 h group was increased slightly and the cells showed multinuclear status; while the cell volume in Doc 24 h+ 3 d group and Doc 24 h+ 5 d group continued to increase, and the nucleus remained multinuclear. The results of cell ploidy analysis also showed that the percentage of polyploid cell subsets was (3.40±0.95)%, (20.80±2.87)% in Doc 24 h group, (55.67±3.85)% in Doc 24 h+3 d group and (76.20±2.51)% in Doc 24 h+5 d group. With the prolongation of withdrawal time, the percentage of polyploid cell subsets was increased, and the difference was statistically significant ( F= 478.054, P < 0.05). The percentage of G 1 and S phase cell subsets in Doc 24 h group was lower than that in the control group, and the percentage of G 2/M phase cell subsets was higher than that in the control group, and the difference was statistically significant (both P < 0.05). The protein expression level of cdc2, P-cdc2 (Thr14), P-cdc2 (Tyr15), P-cyclin B1 (Ser128), P-cyclin B1 (Ser147) in the cells of the control group, Doc 24 h group, Doc 24 h+ 3 d group and Doc 24 h+ 5 d group was down-regulated in sequence, while the expression level of cyclin B1 was up-regulated, and cdc25c was down-regulated in Doc 24 h + 3 d group and Doc 24 h+ 5 d group. Dil staining results showed that the fluorescence of cell-labeled Dil in Doc 24 h group, Doc 24 h+ 3 d group and Doc 24 h + 5 d group did not decrease significantly. CFSE staining showed that the fluorescence intensity of CFSE labeled by polyploid A549 cells did not change significantly with the prolonged withdrawal time. Annexin-V/PI double staining showed that the percentage of apoptotic cell subsets in Doc 24 h group was higher than that in the control group ( P < 0.05), but the percentage of apoptotic cell subsets in Doc 24 h + 3 d group and Doc 24 h + 5 d group was lower than that in Doc 24 h group, while there was no statistically significant difference when compared with the control group ( P > 0.05). Western blot results showed that the expression of bcl-xl and mcl-1 in the control group, Doc 24 h group, Doc 24 h + 3 d group and Doc 24 h + 5 d group was up-regulated in sequence, while the expression of bax and bak in Doc 24 h + 3 d group and Doc 24 h + 5 d group was up-regulated, but down-regulated in Doc 24 h+5 d group. Conclusions:Doc can induce polyploidy of A549 cells in vitro. The cell cycle is blocked in G 2/M phase. After doc treatment, the proliferation of A549 cells is significantly decreased, and the apoptosis of A549 cells is promoted. However, with the prolongation of withdrawal time, apoptosis resistance occurs, and the expression levels of corresponding pro-apoptosis and anti-apoptosis proteins show significant changes. This may be helpful for polyploid tumor cells to produce drug resistance and tumor recurrence after chemotherapy intervention.