title: All-trans retinoic acid-induced hyaluronan production and hyperplasia are partly mediated by EGFR signaling in epidermal keratinocytes.
abstract: All-trans retinoic acid (RA) compromises epidermal differentiation and causes keratinocyte hyperproliferation through mechanisms not completely understood, but may involve the regulatory matrix molecule hyaluronan. In this work, the influences of all-trans RA on epidermal morphology and hyaluronan metabolism were examined in organotypic and monolayer cultures of rat epidermal keratinocytes (REKs). All-trans RA treatment of organotypic REK cultures (10 days) increased the synthesis of hyaluronan, the expression of hyaluronan synthases Has2 and Has3, and the CD44 receptor, with hyperplasia of the epidermis. The hyperplasia and hyaluronan production induced by all-trans RA were blocked with (1) AG1478, an inhibitor of the EGFR; (2) UO126, an inhibitor of the MAPK/ERK kinase, and (3) GM6001, an inhibitor of the matrix metalloproteinases. These effects were consistent with the findings that all-trans RA upregulated heparin-binding epidermal growth factor-like growth factor mRNA expression and increased the phosphorylation of EGFR and extracellular signal-regulated kinase 1/2 (ERK1/2). Interestingly, the activation of EGFR and ERK1/2 was seen already 30 minutes after all-trans RA treatment, suggesting that the activation of this signaling pathway is a primary response to all-trans RA. These results indicate that the effects of all-trans RA on keratinocyte proliferation and hyaluronan synthesis are partly mediated through EGFR signaling.
authors.affiliation: Department of Anatomy, Institute of Biomedicine, University of Kuopio, Kuopio, Finland. Sanna.Pasonen@uku.fi
authors.forename: Sanna M
authors.initials: SM
authors.lastname: Pasonen-Seppänen
authors.forename: Edward V
authors.initials: EV
authors.lastname: Maytin
authors.forename: Kari J
authors.initials: KJ
authors.lastname: Törrönen
authors.forename: Juha M T
authors.initials: JM
authors.lastname: Hyttinen
authors.forename: Vincent C
authors.initials: VC
authors.lastname: Hascall
authors.forename: Donald K
authors.initials: DK
authors.lastname: MacCallum
authors.forename: Anne H
authors.initials: AH
authors.lastname: Kultti
authors.forename: Tiina A
authors.initials: TA
authors.lastname: Jokela
authors.forename: Markku I
authors.initials: MI
authors.lastname: Tammi
authors.forename: Raija H
authors.initials: RH
authors.lastname: Tammi
mesh_terms: D000818:Animals; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004817:Epidermis / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology*; D066246:ErbB Receptors / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018960:Hyaluronan Receptors / Q000032:analysis / Q000378:metabolism; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000032:analysis / Q000378:metabolism*; D006965:Hyperplasia; D015603:Keratinocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D045726:Metalloproteases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D018960:Hyaluronan Receptors; D014212:Tretinoin; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C491097:Has2 protein, rat; C491355:Has3 protein, rat; D000076002:Hyaluronan Synthases; D066246:ErbB Receptors; D020930:MAP Kinase Kinase Kinases; D045726:Metalloproteases