Abstract:

Objective To study the migration of polyploid tumor cells induced by docetaxel, the characteristics of epithelial-mesenchymal transition, and the killing effect of immune cells on them, in order to explore the potential role of polyploid tumor cells in tumor recurrence. Methods The human non-small cell lung cancer A549 cells were treated with 1 μmol/L docetaxel for 24 h, and the cells were collected as Doc 1 d group. After drug removal, the cells were cultured in fresh and complete medium for 3 or 5 days, then the cells were collected as Doc 3 d group or Doc 5 d group respectively. The A549 cells were treated with DMSO for 24 h as control group. Immunofluorescence staining was used to detect cell morphology, flow cytometry was used to analyze cell ploidy, scratch test was used to detect cell migration, Western blotting was used to detect the expression of epithelial-mesenchymal transition related proteins, and lactate dehydrogenase release method was used to evaluate the killing activity of cytokine-induced killer (CIK) cells. Results Compared with the control group, most of the cells in the Doc 1 d group, Doc 3 d group and Doc 5 d group were apoptotic, a few of the surviving cells were significantly larger, and the nucleus was polynuclear. The proportions of polyploid cell subset (DNA content > 4N) in the control group, Doc 1 d group, Doc 3 d group and Doc 5 d group were (1.93±0.55)%, (22.97±2.37)%, (51.30±12.51)% and (67.87±8.31)% respectively, and the difference among the four groups was statistically significant (F=26.521, P<0.001). The proportion of polyploid cell subset in Doc 1 d group, Doc 3 d group and Doc 5 d group was significantly higher than that in the control group (all P<0.001). With the prolongation of withdrawal time, the proportion of polyploid cell subset in Doc 3 d group and Doc 5 d group was significantly higher than that in Doc 1 d group (P=0.009; P=0.004). After 24 h and 48 h culture, the wound healing rates of the control group were both 100%, and the wound healing rates of the Doc 3 d group were (39.10±2.12)% and (46.13±5.32)% respectively, with no significant difference (t=2.126, P=0.051). Compared with the control group at 24 h and 48 h, the cell migration abilities of Doc 3 d group were significantly lower (t=49.756, P<0.001; t=30.825, P<0.001). Compared with the control group, the expression of E-cadherin protein decreased gradually in the Doc 1 d group, Doc 3 d group and Doc 5 d group, the expression of Vimentin protein increased gradually, and the expressions of Snail protein and N-cadherin protein did not change significantly. The killing efficiencies of CIK cells against the cells of the control group, Doc 3 d group and Doc 5 d group were (27.27±1.91)%, (17.87±2.35)%, (9.47±0.51)% respectively, and the difference was statistically significant (F=11.294, P<0.001). The killing efficiency of Doc 3 d group and Doc 5 d group was significantly lower than that of the control group (P=0.004; P<0.001). The killing efficiency of Doc 5 d group was significantly lower than that of Doc 3 d group (P=0.003). Conclusion The migration ability of polyploid tumor cells induced by docetaxel is weakened, but epithelial-mesenchymal transition is likely to occur, and the killing effect of immune cells on them is reduced.

Key words: Carcinoma,non-small-cell lung, Polyploid tumor cells, Docetaxel, Epithelial-mesenchymal transition