Changes of Ubiquitin and bcl-2 During Autophagic Apoptosis of HepG2 Cells Induced by Vincristine

Objective 　To study the changes of ubiquitin during vincristine (VCR) mediated autophagic apoptosis of Hep G2 cells, and determine the influences of inhibiting ubiquitin-proteasome pathway on this apoptosis and bcl-2. Methods 　To induce autophagic apoptosis of Hep G2 cells t reated with VCR. The apoptosis and the expression of ubiquitin were detected with flowcytometry( FCM) and the expression of bcl-2 was examined by RT-PCR technique. Results 　VCR could significantly increase ubiquitin level in Hep G2 cells that underwent autophagic apoptosis ( P < 0. 01) . There are higher apoptosis rate ( P < 0. 01) and lower expression of bcl-2 in the cells by using VCR combined with lactacystin (a proteasome inhibitor) than that in the cells treated with VCR alone. Conclusion Ubiquitin-proteasome pathway is involved in the VCR-induced autophagic apoptosis of hep G2 cells and in regulating the levels of bcl-2, which might have a role in mediating autophagic apoptosis in Hep G2 cells. The inhibition of Ubiquitin-proteasome pathway can enhance VCR-induced apoptosis in Hep G2 cells.