TNF-α promotes gallbladder cancer cell growth and invasion through autocrine mechanisms

Tumor necrosis factor-α (TNF-α) has been suggested to be a putative tumor promoter gene, and autocrine of TNF-α expression has been found in colon cancer and ovarian cancer. As the role of autocrine TNF-α in human gallbladder cancer has not yet been elucidated, the present study examined the expression of TNF-α in gallbladder cancer-derived cell lines. Based on the data, TNF-α mRNA and TNF-α protein expression differed significantly different between the cell lines. In addition, using siRNA targeting TNF-α, the vector, pGPU-GFP-siTNF-α, was constructed and then transfected into the SGC-996 cells (gallbladder cancer cell line) which express high levels of endogenous TNF-α. In vitro experiments indicated that the silencing of TNF-α in the SGC-996 cells significantly suppressed proliferation and invasion. However, apoptosis was not induced by the silencing of TNF-α. Furthermore, we traced the mechanisms underlying these effects and found that the silencing of TNF-α affected the TNF-α-AKT-NF-κB-Bcl-2 pathway in the SGC-996 cells. Our data provide evidence that autocrine TNF-α plays a role as a tumor promoter gene in gallbladder cancer cells, possibly by promoting proliferation and invasion through autocrine mechanisms.