Abstract 2175: Role of p38 MAPK in regulating Cripto-1 expression and signaling in human embryonal carcinoma cells

Abstract

Abstract Cripto-1 (CR-1) is a cell-membrane protein that is overexpressed in several different types of human carcinomas. We have previously shown that TGFβ1 and Activins can enhance CR-1 expression while BMP2 and BMP4 can inhibit CR-1 expression in NTERA-2 embryonal carcinoma cells and in LS174T colon cancer cells. Nevertheless, there is still a very incomplete picture as to the nature of the epigenetic, transcriptional and hormonal factors that might be involved in regulating Cripto-1 expression under different conditions. Previous studies have demonstrated that activation of p38 MAPK can regulate expression of Nodal, a Cripto-1 ligand, during early embryogenesis and is necessary for the specification of mouse cardiomyocytes from embryonic stem cells, which depends upon a Nodal-dependent signaling pathway involving Cripto-1. We therefore evaluated if activation of p38 MAPK might be involved in regulating Cripto-1 expression and Cripto-1 dependent signaling in human embryonal carcinoma cells. In undifferentiated NTERA-2 and NCCIT embryonal carcinoma cells two p38 MAPK inhibitors PD169316 and SB20358 completely inhibited the basal levels of CR-1 mRNA and protein expression in both cell lines. A JNK inhibitor SP600125 had only minor effects on CR-1 mRNA and protein expression whereas the p44/42 MAPK inhibitor U0126 showed no effect. Transfection of specific siRNA against p38 MAPK was also able to significantly interfere with CR-1 mRNA and protein expression in NTERA2 and NCCIT embryonal carcinoma cells. In contrast, knockdown of p44/42 MAPK or JNK with specific siRNA did not significantly affect CR-1 expression in embryonal carcinoma cells. We therefore evaluated whether CR-1 might trigger activation of p38 MAPK in embryonal carcinoma cells and in mouse mammary epithelial cells. Recombinant CR-1 protein was found to stimulate in a delayed fashion (after 50-60 minutes) p38 MAPK phosphorylation in mouse mammary epithelial cells and in embryonal carcinoma cells suggesting a feed-forward activation loop. Whether p38 MAPK functions in undifferentiated embryonal carcinoma cells to regulate CR-1 expression and/or signaling involving regulation of invasion, migration and epithelial to mesenchymal transition in human embryonal carcinoma cells and in mouse mammary epithelial cells is under investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2175. doi:10.1158/1538-7445.AM2011-2175