Robert Beauchamp
Principal Investigator
Last active: 10/31/2018

Transforming growth factor-beta1 enhances Ha-ras-induced expression of cyclooxygenase-2 in intestinal epithelial cells via stabilization of mRNA.

Sheng H, Shao J, Dixon DA, Williams CS, Prescott SM, DuBois RN, Beauchamp RD
J Biol Chem. 2000 275 (9): 6628-35

PMID: 10692471 · DOI:10.1074/jbc.275.9.6628

Oncogenic ras induces the expression of cyclooxygenase-2 (COX-2) in a variety of cells. Here we investigated the role of transforming growth factor-beta (TGF-beta) in the Ras-mediated induction of COX-2 in intestinal epithelial cells (RIE-1). RIE-1 cells were transfected with an inducible Ha-Ras(Val12) cDNA and are referred as RIE-iRas cells. the addition of 5 mM isopropyl-1-thio-beta-D-galactopyranoside (IPTG) induced the expression of Ha-Ras(Val12), closely followed by an increase in the expression of COX-2. Neutralizing anti-TGF-beta antibody partially blocked the Ras-induced increase in COX-2. Combined treatment with IPTG and TGF-beta1 resulted in a 20-50-fold increase in the levels of COX-2 mRNA. The t1/2 of COX-2 mRNA was increased from 13 to 24 min by Ha-Ras induction alone. The addition of TGF-beta1 further stabilized the COX-2 mRNA (t1/2 > 50 min). Stable transfection of a luciferase reporter construct containing the COX-2 3'-untranslated region (3'-UTR) revealed that TGF-beta1 treatment and Ras induction each stabilized the COX-2 3'-UTR. Combined treatment with IPTG and TGF-beta1 synergistically increased the luciferase activity. Furthermore, a conserved AU-rich region located in the proximal COX-2 3'-UTR is required for maximal stabilization of COX-2 3'-UTR by Ras or TGF-beta1 and is necessary for the synergistic stabilization of COX-2 3'-UTR by oncogenic Ras and TGF-beta1.

MeSH Terms (14)

3' Untranslated Regions Animals Cell Line Cyclooxygenase 2 Gene Expression Regulation, Enzymologic Genes, Reporter Intestinal Mucosa Isoenzymes Isopropyl Thiogalactoside Prostaglandin-Endoperoxide Synthases ras Proteins RNA, Messenger Transfection Transforming Growth Factor beta

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