AIM:To investigate the apoptosis in primary gastric cancercells induced by genistein,and the relationship betweenthis apoptosis and expression of bcl-2 and bax.METHODS:MTT assay was used to determine the cell growthinhibitory rate in vitro.Transmission electron microscope andTUNEL staining were used to quantitatively and qualitativelydetect the apoptosis of primary gastric cancer cells beforeand after genistein treatment.Immunohistochemical stainingand RT-PCR were used to detect the expression of apoptosis-associated genes bcl-2 and bax.RESULTS:Genistein inhibited the growth of primary gastriccancer cells in dose-and time-dependent manner.Genisteininduced primary gastric cancer cells to undergo apoptosiswith typically apoptotic characteristics.TUNEL assay showedthat after the treatment of primary gastric cancer cells withgenistein for 24 to 96h,the apoptotic rates of primary gastriccancer cells increased time-dependently.Immunohistochemicalstaining showed that after the treatment of primary gastriccancer cells with genistein for 24 to 96h,the positivity ratesof Bcl-2 proteins were apparently reduced with time andthe positivity rates of Bax proteins were apparently increasedwith time.After exposed to genistein at 20 μmol/L for 24,48,72 and 96 respectively,the density of bcl-2 mRNAdecreased progressively and the density of bax mRNAincreased progressively with elongation of time.CONCLUSION:Genistein is able to induce the apoptosis inprimary gastric cancer cells.This apoptosis may be mediatedby down-regulating the apoptosis- associated bcl-2 geneand up-regulating the expression of apoptosis-associatedbax gene. AIM: To investigate the apoptosis in primary gastric cancer cells induced by genistein, and the relationship betweenthis apoptosis and expression of bcl-2 and bax. METHODS: MTT assay was used to determine the cell growth inhibitory rate in vitro. Transmission electron microscope and TUNEL staining were used to quantitatively and qualitativelydetect the apoptosis of primary gastric cancer cells before and after genistein treatment. Immunohistochemical staining and RT-PCR were used to detect the expression of apoptosis-associated genes bcl-2 and bax.RESULTS: Genistein inhibited the growth of primary gastriccancer cells in dose -and time-dependent manner. Genistein induced primary gastric cancer cells to undergo apoptosis with the apoptotic characteristics. TUNEL assay showed that after the treatment of primary gastric cancer cells with genistein for 24 to 96 h, the apoptotic rates of primary gastriccancer cells increased time-dependently. Immunohistochemical stains showed that after the treatment of pr imary gastriccancer cells with genistein for 24 to 96 h, the positivity rates of Bcl-2 proteins were apparently reduced with time and the positivity rates of Bax proteins were apparently increased with time. After last to genistein at 20 μmol / L for 24, 48, 72 and 96 respectively, the density of bcl-2 mRNA decreased progressively and the density of bax mRNA increased progressively with elongation of time. CONCLUSION: Genistein is able to induce the apoptosis in primary gastric cancer cells. This apoptosis may be mediated by down-regulating the apoptosis- associated bcl- 2 gene and up-regulating the expression of apoptosis-associatedbax gene.