The prostaglandin receptor EP2 activates multiple signaling pathways and beta-arrestin1 complex formation during mouse skin papilloma development.
Prostaglandin E(2) (PGE(2)) is elevated in many tumor types, but PGE(2)'s contributions to tumor growth are largely unknown. To investigate PGE(2)'s roles, the contributions of one of its receptors, EP2, were studied using the mouse skin initiation/promotion model. Initial studies indicated that protein kinase A (PKA), epidermal growth factor receptor (EGFR) and several effectors-cyclic adenosine 3',5'-monophosphate response element-binding protein (CREB), H-Ras, Src, protein kinase B (AKT) and extracellular signal-regulated kinase (ERK)1/2-were activated in 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted papillomas and that PKA and EGFR inhibition (H89 and AG1478, respectively) decreased papilloma formation. EP2's contributions to the activation of these pathways and papilloma development were determined by inhibiting endogenous TPA-induced PGE(2) production with indomethacin (Indo) and concomitantly treating with the EP2 agonist, CAY10399 (CAY). CAY treatment restored papilloma formation in TPA/Indo-treated mice and increased cyclic adenosine 3',5'-monophosphate and PKA activation as measured by p-CREB formation. CAY treatment also increased EGFR and Src activation and their inhibition by AG1478 and PP2 indicated that Src was upstream of EGFR. CAY also increased H-Ras, ERK1/2 and AKT activation, and AG1478 decreased their activation indicating EGFR being upstream. Supporting EP2's contribution, EP2-/- mice exhibited 65% fewer papillomas and reduced Src, EGFR, H-Ras, AKT and ERK1/2 activation. G protein-coupled receptor (GPCR) activation of EGFR has been reported to involve Src's activation via a GPCR-beta-arrestin-Src complex. Indeed, immunoprecipitation of beta-arrestin1 or p-Src indicated the presence of an EP2-beta-arrestin1-p-Src complex in papillomas. The data indicated that EP2 contributed to tumor formation via activation of PKA and EGFR and that EP2 formed a complex with beta-arrestin1 and Src that contributed to signaling and/or EP2 desensitization.
Chun
Kyung-Soo
KS
Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
Lao
Huei-Chen
HC
Trempus
Carol S
CS
Okada
Manabu
M
Langenbach
Robert
R
D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D066246:ErbB Receptors / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D011905:Genes, ras; D051379:Mice; D008810:Mice, Inbred C57BL; D010212:Papilloma / Q000209:etiology* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000502:physiology*; D058307:Receptors, Prostaglandin E, EP2 Subtype; D015398:Signal Transduction / Q000502:physiology*; D012878:Skin Neoplasms / Q000209:etiology* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity; D000071557:beta-Arrestins; D019061:src-Family Kinases / Q000378:metabolism
D019390:Arrestins; C545645:Ptger2 protein, mouse; D018078:Receptors, Prostaglandin E; D058307:Receptors, Prostaglandin E, EP2 Subtype; D000071557:beta-Arrestins; D000242:Cyclic AMP; D066246:ErbB Receptors; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D013755:Tetradecanoylphorbol Acetate