TGF-α inhibits apoptosis of murine gastric pit cells through an NF-κB-dependent pathway

Background & Aims: Recently, some growth factors have been shown to play roles not only as growth factors but also as cell-surviving factors. Transforming growth factor (TGF)-alpha is expressed in normal gastric mucosa. In this study, we investigated the cell-surviving effect of TGF-alpha on gastric mucosal cells and its signaling mechanism. Methods: We used a gastric mucosal cell line, GSM06, and gastric cancer cell line, AGS. Apoptosis was induced by serum depletion or exposure to sodium butyrate. Analysis of apoptosis was performed by DNA ladder assay, measuring the DNA fragmentation ratio (Burton method), and 4',6-diamidino-2-phenylindole staining. Results: TGF-alpha protected gastric mucosal cells against apoptosis induced by serum depletion or sodium butyrate in a dose-dependent manner. This antiapoptotic effect of TGF-alpha was blocked by the pretreatment with reagents that can potentially inhibit NF-kappaB activation, whereas neither MEK inhibitor PD098059 nor PI-3-hinase inhibitor wortmannin abolished this effect. Electrophoretic mobility shift assay showed nuclear factor kappaB (NF-kappaB) activation by TGF-alpha stimulation. TGF-alpha also enhanced the expression of Bcl-2 family proteins in an NF-kappaB- dependent manner. Conclusions: TGF-alpha plays an antiapoptotic role in gastric mucosal cells via the NF-kappaB-dependent pathway.