Regulation of survivin and Bcl-2 in HepG2 cell apoptosis induced by quercetin.
Quercetin, a widely distributed bioflavonoid, has been shown to induce growth inhibition in a variety of human cancer cells. However, the regulation of survivin and Bcl-2 on the quercetin-induced cell-growth inhibition and apoptosis in cancer cells remains unclear. In the present study, we report that quercetin can inhibit proliferation and induce apoptosis in HepG2 cells in dose- and time-dependent manner. Hoechst 33258 and acridine orange/ethidium bromide (AO/EB) staining showed that HepG2 cells underwent the typical morphologic changes of apoptosis characterized by nuclear shrinkage, chromatin condensation, or fragmentation after exposure to quercetin. Cell-cycle analysis reveals a significant increase of the proportion of cells in G(0)/G(1) phase. We also demonstrate that the levels of survivin and Bcl-2 protein expression in HepG2 cells decreased concurrently, and the levels of p53 protein increased significantly after treatment with quercetin by immunocytochemistry analysis. Relative activity of caspase-3 and caspase-9 increased significantly. These data clearly indicate that quercetin-induced apoptosis is associated with caspase activation, and the levels of survivin and Bcl-2. Our results indicate that the expression of survivin may be associated with Bcl-2 expression, and the inhibition expression of survivin, in conjunction with Bcl-2, might cause more pronounced apoptotic effects. Together, concurrent down-regulated survivin and Bcl-2 play an important role in HepG2 cell apoptosis induced by quercetin.
Tan
Jun
J
Bioengineering College, Chongqing University, Chongqing, P. R. China. tanjunmail@126.com
Wang
Bochu
B
Zhu
Liancai
L
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D016193:G1 Phase; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011794:Quercetin / Q000494:pharmacology*; D016192:Resting Phase, Cell Cycle; D000077022:Survivin
D000970:Antineoplastic Agents; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D000077022:Survivin; D011794:Quercetin; D053148:Caspase 3; D053453:Caspase 9