Modulating Bcl-2 family proteins and caspase-3 in induction of apoptosis by paeoniflorin in human cervical cancer cells

Paeoniflorin (PF), the principal bioactive component in the paeony root, has been used alone or combined with other herbs for many years in traditional Chinese medicine. New studies have shown that PF possesses an antitumor effect. However, the effect of PF on human cervical cancer cells has not been reported previously. This study determined the effect of PF on human cervical cancer cell line (HeLa) cells by the methyl thiazolyl tetrazolium (MTT) assay, flow cytometry with annexin V‐fluorescein isothiocyanate (FITC)/propidium iodide (PI) technology, the transmission electron microscope (TEM) and immunocytochemical technique. After treatment with PF, the proliferation of HeLa cells was inhibited in a dose and time‐dependent manner (p < 0.05). The apoptosis rate of HeLa cells increased with ascending concentrations of PF (p < 0.05) and the proportion of HeLa cells in S phase showed an increasing trend also. Typical apoptotic changes of HeLa cells exposed to PF were seen under the TEM. Meanwhile, there was a decrease in the expression of Bcl‐2 and an enhancement in the expression of Bax and caspase‐3 genes compared with the control group (p < 0.05). In conclusion, PF can induce significantly the apoptosis of HeLa cells, which may be demonstrated by the down‐regulation of anti‐apoptosis gene Bcl‐2 and the up‐regulation of pro‐apoptosis genes Bax and caspase‐3. Copyright © 2011 John Wiley & Sons, Ltd.