title: Heregulin-mediated ErbB2-ERK signaling activates hyaluronan synthases leading to CD44-dependent ovarian tumor cell growth and migration.
abstract: Heregulin (HRG)-induced cell responses are mediated by the ErbB family of tyrosine kinase receptors. In this study we have investigated HRG activation of ErbB2, extracellular signal-regulated kinase (ERK) signaling, and their role in regulating hyaluronan synthase (HAS) activity in human ovarian tumor cells (SK-OV-3.ipl cells). Immunological and biochemical analyses indicate that ErbB2, ErbB3, and ErbB4 are all expressed in SK-OV-3.ipl cells and that ErbB4 (but not ErbB3) is physically linked to ErbB2 following HRG stimulation. Furthermore, our data indicate that the HRG-induced ErbB2.ErbB4 complexes stimulate ErbB2 tyrosine kinase, which induces both ERK phosphorylation and kinase activity. The activated ERK then increases the phosphorylation of HAS1, HAS2, and HAS3. Consequently, all three HAS isozymes are activated resulting in hyaluronan (HA) production. Because HRG-mediated HAS isozyme phosphorylation/activation can be effectively blocked by either AG825 (an ErbB2 inhibitor) or thiazolidinedione compound (an ERK blocker), we conclude that ErbB2-ERK signaling and HAS isozyme phosphorylation/HA production are functionally coupled in SK-OV-3.ipl cells. HRG also promotes HA- and CD44-dependent oncogenic events (e.g. CD44-Cdc42 association, p21-activated kinase 1 activation, and p21-activated kinase 1-filamin complex formation) and tumor cell-specific behaviors in an ErbB2-ERK signaling-dependent manner. Finally, we have found that the down-regulation of HAS isozyme expression (by transfecting cells with HAS1/HAS2/HAS3-specific small interfering RNAs) not only inhibits HRG-mediated HAS phosphorylation/activation and HA production but also impairs CD44-specific Cdc42-PAK1/filamin signaling, cytoskeleton activation and tumor cell behaviors. Taken together, these findings clearly indicate that HRG activation of ErbB2-ERK signaling modulates HAS phosphorylation/activation and HA production leading to CD44-mediated oncogenic events and ovarian cancer progression.
authors.affiliation: Department of Medicine, University of California at San Francisco, USA. lilly.bourguignon@ucsf.edu
authors.forename: Lilly Y W
authors.initials: LY
authors.lastname: Bourguignon
authors.forename: Eli
authors.initials: E
authors.lastname: Gilad
authors.forename: Karine
authors.initials: K
authors.lastname: Peyrollier
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D003285:Contractile Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D064448:Filamins; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D014453:Glucuronosyltransferase / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D000076002:Hyaluronan Synthases; D007527:Isoenzymes / Q000096:biosynthesis; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D008840:Microfilament Proteins / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D020890:Neuregulin-1; D010051:Ovarian Neoplasms / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D066247:Receptor, ErbB-4; D045162:Thiazolidinediones / Q000494:pharmacology; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D054462:p21-Activated Kinases
chemical_list: D003285:Contractile Proteins; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D064448:Filamins; D014453:Glucuronosyltransferase; D018960:Hyaluronan Receptors; D000076002:Hyaluronan Synthases; D007527:Isoenzymes; D008840:Microfilament Proteins; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; D020890:Neuregulin-1; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D018719:Erb-b2 Receptor Tyrosine Kinases; D066247:Receptor, ErbB-4; D045162:Thiazolidinediones; D020764:cdc42 GTP-Binding Protein; D054462:p21-Activated Kinases; C497483:CD44 protein, human; C094131:NRG1 protein, human; C089946:2,4-thiazolidinedione; C508053:ERBB2 protein, human; C587689:ERBB4 protein, human; C587690:Erbb4 protein, mouse; C515903:PAK1 protein, human; C515905:Pak1 protein, mouse