Ethyl acetate extract of Patrinia scabiosaefolia downregulates anti-apoptotic Bcl-2/Bcl-XL expression, and induces apoptosis in human breast carcinoma MCF-7 cells independent of caspase-9 activation

Patrinia scabiosaefolia Fisch. is a Chinese medicinal herb used traditionally for treating intestinal carbuncle. Although Patrinia scabiosaefolia has also been suggested for cancer therapy, there has not been any scientific evidence supporting this application. In this study, a panel of human cancer cells, including breast carcinoma MCF-7; hepatocellular carcinoma HepG2; skin melanoma A375; lung carcinoma A549 and prostate adenocarcinoma PC-3, were treated in vitro with ethyl acetate extract of Patrinia scabiosaefolia (EAE-PS) for 48 h. Results from MTT study showed that MCF-7 was the most responsive (IC50 = 112.3 μg/ml) while PC-3 was the most resistant (IC50 = 348.7 μg/ml) one to cell growth inhibition. DNA flow cytometry demonstrated that EAE-PS induced apoptosis in the resistant MCF-7 cells by 14.5-fold of the control level after 36 h of treatment. Immunoblot studies further illustrated that although EAE-PS downregulated the anti-apoptotic Bcl-2/Bcl-XL expression in breast cancer cells, the induced apoptosis could not be prevented by the caspase-9 inhibitor (Z-LEHD-FMK). All these results suggest that EAE-PS retards MCF-7 cell growth by activating the caspase-independent mitochondrial cell death pathway. Results from this study support future research and development of the bioactive ingredients from Patrinia scabiosaefolia as anticancer agents, especially against those apoptosis-resistant cancers with deregulated Bcl-2/Bcl-XL expression.