title: Cyclic AMP promotes cAMP-responsive element-binding protein-dependent induction of cellular inhibitor of apoptosis protein-2 and suppresses apoptosis of colon cancer cells through ERK1/2 and p38 MAPK.
abstract: We recently reported that cAMP suppresses apoptosis in colon cancer cells and induces cellular inhibitor of apoptosis protein-2 (c-IAP2) via a cAMP-responsive element (CRE), suggesting a mechanism for chemoprevention of colon cancer by non-steroidal anti-inflammatory drugs. In this study, we used T84 human colon cancer cells to define the pathway by which increases in cAMP induce c-IAP2 expression. Treatment with several different cAMP agonists stimulated phosphorylation of CRE-binding protein (CREB) and activated expression of c-IAP2 in a CREB-dependent manner. Studies with pharmacological inhibitors revealed that cAMP-dependent phosphorylation of CREB required activation of ERK1/2 and p38 MAPK but was largely independent of protein kinase A. Immunoblots and transcriptional reporter assays using specific inhibitors, as well as expression of constitutively active forms of MEK1 and MKK3, showed that c-IAP2 induction by cAMP is regulated predominantly through ERK1/2 and p38 MAPK and suggested involvement of p90 ribosomal protein S6 kinase and mitogen and stress response kinase-1 as well. Consistent with those results, we found that cAMP-dependent suppression of apoptosis was blocked by treatment with inhibitors of ERK1/2 and p38 MAPK. We conclude that cAMP can induce c-IAP2 expression in colon cancer cells through CREB phosphorylation and CRE-dependent transcription in a manner that involves activation of ERK1/2 and p38 MAPK. These results emphasize that activation of kinases other than protein kinase A can mediate the actions of agents that increase cAMP, particularly in the regulation of CREB-dependent events.
authors.affiliation: Department of Pharmacology, University of California, San Diego, La Jolla, California 92093-0636, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishihara
authors.forename: Michael
authors.initials: M
authors.lastname: Hwang
authors.forename: Shinae
authors.initials: S
authors.lastname: Kizaka-Kondoh
authors.forename: Lars
authors.initials: L
authors.lastname: Eckmann
authors.forename: Paul A
authors.initials: PA
authors.lastname: Insel
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology*; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D051034:Inhibitor of Apoptosis Proteins; D008156:Luciferases / Q000378:metabolism; D048369:MAP Kinase Kinase 1; D048371:MAP Kinase Kinase 3; 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*; D008954:Models, Biological; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D051034:Inhibitor of Apoptosis Proteins; D011506:Proteins; D000242:Cyclic AMP; D008156:Luciferases; D011505:Protein-Tyrosine Kinases; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D017868:Cyclic AMP-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048371:MAP Kinase Kinase 3; C482125:MAP2K1 protein, human; C482530:MAP2K3 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases