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Ang II and EGF synergistically induce COX‐2 expression via CREB in intestinal epithelial cells
Author(s) -
Pham Hung,
Chong Benny,
Vincenti Romina,
Slice Lee W.
Publication year - 2008
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.21167
Subject(s) - creb , mapk/erk pathway , transfection , phosphorylation , p38 mitogen activated protein kinases , microbiology and biotechnology , biology , epidermal growth factor , chemistry , cancer research , transcription factor , cell culture , receptor , biochemistry , gene , genetics
Abstract Cyclooxygenase (COX)‐2 derived prostaglandins (PGs) play a major role in intestinal inflammation and colorectal carcinogenesis. Because COX‐2 is the rate‐limiting step in the production of PGs, mechanisms that regulate COX‐2 expression control PG production in the cell. Using the non‐tumorigenic, rat intestinal epithelial cell, IEC‐18, we demonstrate that co‐activation of endogenously expressed AT 1 receptor and EGFR resulted in synergistic expression of COX‐2 mRNA and protein involving transcriptional and post‐transcriptional mechanisms. Ang II and EGF induced transient phosphorylation of ERK, p38 MAPK and CREB. Co‐stimulation with Ang II and EGF prolonged phosphorylation of ERK, p38 MAPK , and CREB. The p38 MAPK selective inhibitor, SB202190, but not the MEK selective inhibitor, PD98059, or the EGFR kinase inhibitor, AG1478, inhibited Ang II‐dependent COX‐2 expression and CREB phosphorylation. EGF‐dependent COX‐2 expression and CREB phosphorylation were inhibited by SB202190, PD98059, and AG1478. Inhibition of CREB expression using two separate RNAi methods blocked COX‐2 expression by Ang II and EGF. Expression of a dominant negative CREB mutant inhibited Ang II‐ and EGF‐dependent induction of the COX‐2 promoter. Ang II induced luciferase expression in cells transfected with the CRE‐luc reporter vector and cells co‐transfected with Gal4‐luc reporter vector and a Gal4‐CREB expression vector. Chromatin immunoprecipitation assays demonstrated CREB binding to the proximal rat COX‐2 promoter region containing a CRE cis‐acting element. These results indicate that co‐stimulation with Ang II and EGF synergistically induced COX‐2 expression in these intestinal epithelial cells through p38 MAPK mediated signaling cascades that converge onto CREB. J. Cell. Physiol. 214:96–109, 2008. © 2007 Wiley‐Liss, Inc.