Signal transduction pathways regulating cyclooxygenase-2 expression: potential molecular targets for chemoprevention.
Expression of cyclooxygenase-2 (COX-2) has been reported to be elevated in human colorectal adenocarcinoma and other tumors, including those of breast, cervical, prostate, and lung. Genetic knock-out or pharmacological inhibition of COX-2 has been shown to protect against experimentally-induced carcinogenesis. Results from epidemiological and laboratory studies indicate that regular intake of selective COX-2 inhibitors reduces the risk of several forms of human malignancies. Thus, it is conceivable that targeted inhibition of abnormally or improperly elevated COX-2 provides one of the most effective and promising strategies for cancer chemoprevention. The COX-2 promoter contains a TATA box and binding sites for several transcription factors including nuclear factor-kappaB (NF-kappaB), nuclear factor for interleukin-6/CCAAT enhancer-binding protein (NF-IL6/C/EBP) and cyclic AMP response element (CRE) binding protein. Upregulation of COX-2 is mediated by a variety of stimuli including tumor promoters, oncogenes, and growth factors. Stimulation of either protein kinase C (PKC) or Ras signaling enhances mitogen-activated protein kinase (MAPK) activity, which, in turn, activates transcription of cox-2. Celecoxib, the first US FDA approved selective COX-2 inhibitor, initially developed for the treatment of adult rheumatoid arthritis and osteoarthritis, has been reported to reduce the formation of polyps in patients with familial adenomatous polyposis. This COX-2 specific inhibitor also protects against experimentally-induced carcinogenesis, but the underlying molecular mechanisms are poorly understood. The present review covers the signal transduction pathways responsible for regulating COX-2 expression as novel molecular targets of chemopreventive agents with celecoxib as a specific example.
Chun
Kyung-Soo
KS
Laboratory of Biochemistry and Molecular Toxicology, College of Pharmacy, Seoul National University, 151-742, South Korea.
Surh
Young-Joon
YJ
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D000068579:Celecoxib; D018890:Chemoprevention; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D009369:Neoplasms / Q000517:prevention & control; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D011720:Pyrazoles; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology* / Q000627:therapeutic use; D014158:Transcription, Genetic / Q000187:drug effects
D000970:Antineoplastic Agents; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D011720:Pyrazoles; D013449:Sulfonamides; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D000068579:Celecoxib