Background Bcl-2,the anti-apoptotic protein is overexpressed in the majority of gastric cancers and associated with its pathogenesis.To better understanding of the role of Bcl-2,RNA interference(RNAi)was used to inhibit Bcl-2 expression in the human gastric cancer cells in vitro and in vivo.Methods Bcl-2 small interfering RNA (siRNA) was transfected into human gastric cancer cells SGC-7901,and Bcl-2 expression was monitored by real-time polymerase chain reaction (PCR) and Western blot.Cell proliferation,apoptosis,and telomerase activity were examined by MTT,flow cytometry.and TRAP assay,respectively.Gastric cancer cells treated with 100 nmol/L Bcl-2 siRNA were subcutaneously transplanted into nude mice and tumor growth was assessed.Results Bcl-2 siRNA significantly inhibited the expression of Bcl-2 in human gastric cancer cells at both mRNA and protein levels in a time-and dose-dependent manner.Bcl-2 siRNA also decreased telomerase activity (by 78.76%)and increased the rate of apoptosis(by 37.47%).SGC-7901 cell growth was also significantly suppressed in vivo and in vitro.Conclusions Bcl-2 expression knockdown suppressed the growth of gastric cancer cells.Thus,Bcl-2 may play a very important role in carcinogenesis of gastric cancer and its knockdown may offer a new potential gene therapy approach for human gastric cancer in future.