TY - JOUR
T1 - Induction of cyclooxygenase-2 by activated Ha-ras oncogene in rat-1 fibroblasts and the role of mitogen-activated protein kinase pathway
AU - Sheng, Hongmiao
AU - Williams, Christopher S.
AU - Shao, Jinyi
AU - Liang, Peng
AU - DuBois, Raymond N.
AU - Beauchamp, R. Daniel
PY - 1998/8/21
Y1 - 1998/8/21
N2 - Elevated cyclooxygenase-2 (COX-2) expression and activity have been observed in several different transformed cell types that express mutated ras genes. To investigate the mechanism of increased COX-2 expression following Ras-mediated transformation, Rat-1:iRas cell line was transfected with an Ha- Ras(Val-12) cDNA expression vector that is under the transcriptional control of the lac operon and is inducible with isopropyl-1-thio-β-D- galactopyranoside (IPTG). IPTG treatment caused parallel increases in the levels of Ha-Ras and COX-2 proteins in Rat-1:iRas cells. The increased expression of COX-2 was accompanied by increased prostaglandin E2 production. Selective inhibition of COX-2 activity suppressed the production of prostaglandin E2 by > 90% but did not alter the progress of the morphological transformation. The level of COX-2 mRNA was up-regulated by activated Ha-Ras. Induction of Ras increased the transcription of COX-2 by 44.3 ± 10.1% and increased the half-life of COX-2 mRNA by ~3.5-fold. A specific mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) inhibitor (PD 98059) caused a delay in both the activation of ERK1/2 and the induction of COX-2 in IPTG-induced Rat-1:iRas cells. Inhibition of ERK activity by PD 98059 also suppressed the induction of COX- 2 by epidermal growth factor in intestinal epithelial cells and significantly reduced the expression of COX-2 in Ha-Ras-transformed rat intestinal epithelial cells. ERK activity appears to be required for induction of COX-2 by Ras.
AB - Elevated cyclooxygenase-2 (COX-2) expression and activity have been observed in several different transformed cell types that express mutated ras genes. To investigate the mechanism of increased COX-2 expression following Ras-mediated transformation, Rat-1:iRas cell line was transfected with an Ha- Ras(Val-12) cDNA expression vector that is under the transcriptional control of the lac operon and is inducible with isopropyl-1-thio-β-D- galactopyranoside (IPTG). IPTG treatment caused parallel increases in the levels of Ha-Ras and COX-2 proteins in Rat-1:iRas cells. The increased expression of COX-2 was accompanied by increased prostaglandin E2 production. Selective inhibition of COX-2 activity suppressed the production of prostaglandin E2 by > 90% but did not alter the progress of the morphological transformation. The level of COX-2 mRNA was up-regulated by activated Ha-Ras. Induction of Ras increased the transcription of COX-2 by 44.3 ± 10.1% and increased the half-life of COX-2 mRNA by ~3.5-fold. A specific mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) inhibitor (PD 98059) caused a delay in both the activation of ERK1/2 and the induction of COX-2 in IPTG-induced Rat-1:iRas cells. Inhibition of ERK activity by PD 98059 also suppressed the induction of COX- 2 by epidermal growth factor in intestinal epithelial cells and significantly reduced the expression of COX-2 in Ha-Ras-transformed rat intestinal epithelial cells. ERK activity appears to be required for induction of COX-2 by Ras.
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U2 - 10.1074/jbc.273.34.22120
DO - 10.1074/jbc.273.34.22120
M3 - Article
C2 - 9705357
AN - SCOPUS:0032555484
SN - 0021-9258
VL - 273
SP - 22120
EP - 22127
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 34
ER -