AIM: To investigate the effect of Euphorbia esula(E. esula) extract in inhibiting proliferation and inducing apoptosis in SGC-7901 cells.METHODS: E. esula extract at different concentrations was used to inhibit proliferation and induce apoptosis of human gastric carcinoma SGC-7901 cells. Inhibition of proliferation was detected with thiazolyl blue assay, and apoptosis was detected with fluorescence microscopy, transmission electron microscopy, and flow cytometry. The mechanisms were studied by measurement of caspase-3 and caspase-8 activities and Bax and Bcl2 m RNA expression.RESULTS: The thiazolyl blue assay showed that SGC-7901 cell viability and proliferation were inhibited significantly by E. esula extract in a timeand concentration-dependent manner. Fluorescence microscopy revealed that the cell nuclei showed the characteristic changes of apoptosis, such as uneven staining and chromatin marginalization. Some key features of apoptosis were also observed undertransmission electron microscopy, which included cellular shrinkage and the foaming or bubbling phenomenon. When the cells were analyzed by flow cytometry, a sub-G1 peak could be seen clearly. Spectrophotometric assay of caspase-3 and caspase-8 activities in the treated cells showed an approximately two-fold increase. Reverse transcriptase polymerase chain reaction showed that Bax m RNA expression was upregulated, while Bcl2 m RNA expression was downregulated.CONCLUSION: E. esula extract inhibited proliferation and induced apoptosis in SGC-7901 cells, in a caspasedependent manner, involving upregulation of Bax and downregulation of Bcl2. AIM: To investigate the effect of Euphorbia esula (E. esula) extract in inhibiting proliferation and inducing apoptosis in SGC-7901 cells. METHODS: E. esula extract at different concentrations was used to inhibit proliferation and induce apoptosis of human gastric carcinoma SGC- 7901 cells. Inhibition of proliferation was detected with thiazolyl blue assay, and apoptosis was detected with fluorescence microscopy, transmission electron microscopy, and flow cytometry. The mechanisms were studied by measurement of caspase-3 and caspase-8 activities and Bax and Bcl2 m RNA expression.RESULTS: The thiazolyl blue assay showed that the cell nuclei showed the characteristic changes of apoptosis, such as of the cell nuclei showed the characteristic changes of apoptosis, staining and chromatin marginalization. Some key features of apoptosis were also observed undertransmission electron m icroscopy, which included cellular shrinkage and the foaming or bubbling phenomenon. When the cells were analyzed by flow cytometry, a sub-G1 peak could be seen clearly. Spectrophotometric assay of caspase-3 and caspase-8 activities in the treated cells showed an approximately Two-fold increase. Reverse transcriptase polymerase chain reaction showed that Bax m RNA expression was upregulated, while Bcl2 m RNA expression was downregulated. CONCLUSION: E. esula extract inhibited proliferation and induced apoptosis in SGC-7901 cells, in a caspase dependent manner, involving upregulation of Bax and downregulation of Bcl2.