Overexpression of protein kinase C-β1 isoenzyme suppresses indomethacin-induced apoptosis in gastric epithelial cells

Abstract

Background & Aims: We have previously reported that nonsteroidal anti-inflammatory drugs (NSAIDs) could induce apoptosis of gastric epithelial cells both in vivo and in vitro. This study investigated the role of protein kinase C (PKC) isoforms in the regulation of NSAID-induced apoptosis. Methods: Protein levels of 12 PKC isoforms in AGS cells, in the presence or absence of indomethacin, were determined by Western blot. The effect of PKC-β1 overexpression by transfection with its complementary DNA (cDNA) on indomethacin-induced apoptosis and apoptosis-related genes, including p53, p21 waf1/cip1, and c-myc, was further investigated. Results: Treatment with indomethacin decreased the abundance of PKC-β1 and increased that of PKC-β2, η, and ϵ, but did not alter the expression of PKC α, γ, ζ, δ, ι, and μ. Overexpression of PKC-β1 attenuated the apoptotic response of AGS cells to indomethacin, associated with overexpression of p21 waf1/cip1 in both messenger RNA and protein levels. Inhibition of PKC-β1-mediated overexpression of p21 waf1/cip1 by its antisense cDNA partially reduced the antiapoptotic effect of PKC-β1. Conclusions: Indomethacin-induced apoptosis in gastric cancer cells is partly mediated by differential regulation of PKC isoform expression. Enhanced expression of exogenous PKC-β1 protects against indomethacin-induced apoptosis through up-regulation of p21 waf1/cip1. GASTROENTEROLOGY 2000;118:507-514