[Effects of p16/pRb and JNK signaling pathways in hydroquinone-induced malignant transformation of TK6 cells].

ABSTRACT

Objective: To investigate the cell cycle and apoptosis in hydroquinone (HQ) -induced malignant transformation of TK6 cells and its related regulatory mechanisms. Methods: TK6 cells were exposed to 20 µmol/L HQ, 24 h/time, once a week, for 19 weeks as experimental group and TK6 cells treated with phosphate buffer (PBS) for 19 weeks was used as control group from March 2014. In regulatory mechanism research, the cells were divided into four groups control group, experimental group, control inhibitor group and experimental inhibitor group (inhibitor groups were added 10 µmol/L P600125) . Cell cycle and apoptosis were detected by flow cytometry. The protein expression of cell cycle-related proteins and JNK signaling pathway proteins were detected by Western blot. Results: Flow cytometry showed that compared with control group, the ratio of cells in the G0/G1 phase of the experimental group was significantly decreased (P=0.001) , and the ratio of cells in the S phase was significantly increased (P=0.002) . Western blotting demonstrated that the protein expressions of p-Rb (Ser780) , E2F1, Cyclin D1, p-p16 (Ser152) , JNK1, p-JNK1 (Thr183/Tyr185) , c-jun, p-c-jun (Ser63) (P=0.015, 0.021, 0.001, 0.001, 0.005, 0.001, 0.039, 0.003) were up-regulated, while the protein expressions of Rb (P=0.048) and p16 (P=0.002) were significantly down-regulated. After exposed to SP600125, compared with experimental group, there were no significant changes in cell cycle distribution (P=0.946) and apoptosis rate (P=0.923) in experimental inhibitor group. The expression of c-jun (P=0.040) protein was down-regulated, while the expression of Rb (P=0.027) protein was up-regulated in experimental inhibitor group. Conclusion: In HQ-induced TK6 cells malignant transformation, the cell cycle is arrested in the S phase, and the p16/pRb signaling pathway is inhibited, while the JNK signaling pathway is activated. However, the activated JNK signaling pathway may not be involved in the regulation of cell cycle.