OBJECTIVETo investigate the expression of apoptosis-related protein Bcl-w in adenocarcinoma of the small intestine, and the apoptotic effect of Bcl-w siRNA on small intestinal adenocarcinoma cells HuTu-80.

METHODSForty-two tissue samples were examined in our study, including 7 cases from human small intestinal adenocarcinoma, and 35 cases from normal small intestine served as control. The expression of Bcl-w was detected by immunohistochemistry (IHC). Western blot analysis was performed to confirm whether Bcl-w siRNA could effectively down-regulate Bcl-w protein after HuTu-80 cells were transfected with Bcl-w siRNA. The cells were treated with chemotherapeutic agent 5-Fu to observe whether Bcl-w protein-silecing affects the pro-apoptotic effect of 5-Fu. Flow cytometry analysis was used for assessment of apoptotic rate of HuTu-80 cells cultured with Bcl-w siRNA alone, with 5-Fu alone, and with combination of Bcl-w siRNA and 5-Fu, using untreated HuTu-80 cells as control.

RESULTSThe positive rate of Bcl-w expression was significantly higher in small intestinal adenocarcinoma than that in normal tissue (85.7% vs. 25.7%, P=0.005). Compared with the control group, Bcl-w siRNA transfection effectively down-regulated the expression of Bcl-w protein (P<0.05). The apoptosis in HuTu-80 cells was not increased significantly in Bcl-w-/-cells compared with that of control group (12.4±2.2)% vs. (8.6±1.7)% (P>0.05). However, compared with the 5-Fu group, the apoptosis in HuTu-80 cells was effectively enhanced after combination treatment with Bcl-w siRNA and 5-Fu (45.7±2.1)% vs. (71.6±3.2)% (P<0.05).

CONCLUSIONSBcl-w protein plays a significant role in the carcinogenesis of human small intestinal adenocarcinoma. Down-regulation of Bcl-w protein in small intestine adenocarcinoma HuTu-80 cells leads them susceptible to 5-Fu.