Effects of Taoerqi extract on proliferation and apoptosis of human breast carcinoma cell line MCF-7

AIM: To investigate the effects and related mechanism of Taoerqi on the proliferation inhibition and onset of apoptosis in breast carcinoma cell line MCF-7.METHODS: Antiproliferative effect of Taoerqi extract against MCF-7 was tested by MTT assay,morphologic changes of MCF-7 were observed by inverted microscope,electron microscope and HE staining,and cell apoptosis percentage and cell cycle phase distribution of MCF-7 were measured by flow cytometric assay.The expressions of proliferation-and apoptosis-associated proteins were determined by immunocytochemical method.RESULTS: A time-dependent and dose-dependent proliferation inhibition was demonstrated in Taoerqi extract.With the Taoerqi extract treatment of 1,2 and 3 mg/L for 72 h,the inhibitory rate was 43.0%,54.9%,78.5% respectively.The characteristic morphological changes of apoptosis were observed in cells after treated by 2 mg/L of Taoerqi,and many multinucleate giant cells were also found.Taoerqi induced a G2/M cell cycle arrest and the apoptosis was time-and dose-dependent.With the treatment of 2 mg/L Taoerqi for 48 h,the protein expressions of PCNA and Bcl-2 decreased from(154.78±0.16) and(85.56±0.09) to(78.46±0.15) and((40.43±)0.07) (P0.01),while p21~(WAF1/CIP1) and c-Myc increased from(92.32±0.12) and(114.48±0.14) to((125.54±)0.09) and(156.52±0.08)(P0.01).CONCLUSION: The time-dependent and dose-dependent proliferation inhibitory effect of Taoerqi extract on breast cancer cells appears to be caused by the up-regulation of p21~(WAF1/CIP1) expression,down-regulation of PCNA expression,and the apoptosis is related to the down-regulation of anti-apoptotic protein Bcl-2 and the up-regulation of c-Myc protein.G2/M arrest is also associated with apoptosis.