Posttranscriptional regulation of cyclooxygenase-2 in rat intestinal epithelial cells.
Modulation of cyclooxygenase-2 (COX-2) mRNA stability plays an important role in the regulation of its expression by oncogenic Ras. Here, we evaluate COX-2 mRNA stability in response to treatment with two known endogenous promoters of gastrointestinal cancer, the bile acid (chenodeoxycholate; CD) and ceramide. Treatment with CD and ceramide resulted in a 10-fold increase in the level of COX-2 protein and a four-fold lengthening of the half-life of COX-2 mRNA. COX-2 mRNA stability was assessed by Northern blot analysis and by evaluating the AU-rich element located in the COX-2 3'-UTR. A known inhibitor of mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK), PD98059, reversed the effects of CD or ceramide to stabilize COX-2 mRNA. Overexpression of a dominant-negative ERK-1 or ERK-2 protein also led to destabilization of COX-2 mRNA. Treatment with a p38 MAPK inhibitor, PD169316, or transfection with a dominant-negative p38 MAPK construct reversed the effect of CD or ceramide to stabilize COX-2 mRNA. Expression of a dominant-negative c-Jun N-terminal kinase (JNK) had no effect on COX-2 mRNA stability in cells treated with CD or ceramide. We conclude that posttranscriptional mechanisms play an important role in the regulation of COX-2 expression during carcinogenesis.
Zhang
Z
Z
Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Sheng
H
H
Shao
J
J
Beauchamp
R D
RD
DuBois
R N
RN
D000818:Animals; D002460:Cell Line; D002518:Ceramides / Q000494:pharmacology; D002635:Chenodeoxycholic Acid / Q000494:pharmacology; D051546:Cyclooxygenase 2; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000201:enzymology; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D048051:p38 Mitogen-Activated Protein Kinases
D002518:Ceramides; D007527:Isoenzymes; D012333:RNA, Messenger; D002635:Chenodeoxycholic Acid; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases