Effect of Stemona tuberosa Alkaloids on Apoptosis of SMMC-7721 Cells and Expression of Bcl-2， Bax， and Cleaved Caspase-3 / 中国实验方剂学杂志

Objective:To investigate the effect of<italic> Stemona tuberosa</italic> alkaloids on the apoptosis of human hepatoma SMMC-7721 cells and the expression of apoptosis-related proteins including B lymphocytoma-2 （Bcl-2）， Bcl-2-associated X protein （Bax）， and cleaved cysteinyl aspartate-specific protease-3 （cleaved Caspase-3）. Method:SMMC-7721 cells were routinely cultured， passaged， and treated with various concentrations （50， 75， 112， 167， and 250 mg·L^-1） of <italic>S. tuberosa </italic>alkaloids， while those in the blank control group were only treated with 10% fetal bovine serum. The cell proliferation was determined by tetrazolium bromide （MTT） colorimetry and colony assay and the cell apoptosis by Hoechst 33258 staining. The protein expression levels of Bcl-2， Bax， and cleaved Caspase-3 were detected by Western blot. Result:<italic>S. tuberosa</italic> alkaloids inhibited the proliferation of SMMC-7721 cells， and the inhibition rate was significantly increased in comparison with that in the blank control group （<italic>P</italic><0.01）， with the half maximal inhibitory concentrations （IC₅₀） at 24 h， 48 h， and 72 h being （173.36±8.75）， （112.14±16.50）， and （96.41±2.60）mg·L^-1， respectively. The cell colony-inhibitory activity was significantly increased in a dose-dependent manner （<italic>P</italic><0.01）. Compared with the blank control group， <italic>S. tuberosa</italic> alkaloids promoted the apoptosis of SMMC-7721 cells， manifested as increased number of apoptotic cells and elevated apoptotic rate （<italic>P</italic><0.01）. The typical morphological changes such as brightly blue-fluorescent condensed nuclei， cytoplasmic shrinking， and karyopyknosis were found under the upright fluorescence microscope. As revealed by comparison with the blank control group， the expression of Bcl-2 was significantly down-regulated （<italic>P</italic><0.01）， while the protein expression levels of pro-apoptotic protein Bax and cleaved Caspase-3 in the 75， 112， 167， and 250 mg·L^-1 <italic>S. tuberosa</italic> alkaloids groups were significantly up-regulated （<italic>P</italic><0.01）. Conclusion:<italic>S. tuberosa </italic>alkaloids inhibit the proliferation of SMMC-7721 cells and promote their apoptosis possibly by inhibiting Bcl-2 protein expression and promoting Bax and cleaved Caspase-3 protein expression.