Objective To explore the inducing effect of platycodin D on the apoptosis of human transitional cell carcinoma 5637 cell lines and related molecular mechanism.

Methods The change of cell morphology was observed by HE staining and transmission electron microscope. The apoptosis was detected by flow cytometry. The change of apoptosis-related proteins expression was detected by Western blot. The mRNA expressions of p53, Bcl-2 and Bax related with apoptosis pathway were detected by PCR method. The expressions of apoptosis-related proteins in 5637 cells were detected by immunocytochemical method.

Results From HE staining and transmission electron microscope, we found the apoptosis of 5637 cells treated with platycodin D. The number of apoptotic and dead cells was increased, with visible apoptotic bodies in platycodin D group. Compared with control group, the cell apoptosis index of platycodin D group was significantly higher(P < 0.01); the expressions of Survivin and Livin were significantly decreased(P < 0.05); the expressions of Caspase-9, Caspase-8, Caspase-3 and Cyt-c were increased(P < 0.05); the expressions of p53 and Bax mRNA were greatly increased but Bcl-2 mRNA was decreased(P < 0.01); the expressions of Bax, Caspase-9, Caspase-8 and Caspase-3 were increased, but Bcl-2 was decreased(P < 0.01).

Conclusion Platycodin D could induce the apoptosis of 5637 cells, which may be related to up-regulating Caspase-9, Caspase-8, Caspase-3, Cyt-c, p53 expression, down-regulating Bcl-2 expression and activating the mitochondrial pathway and death receptor pathway.