title: Hyaluronan-CD44 interaction with neural Wiskott-Aldrich syndrome protein (N-WASP) promotes actin polymerization and ErbB2 activation leading to beta-catenin nuclear translocation, transcriptional up-regulation, and cell migration in ovarian tumor cells.
abstract: In this study we have investigated the interaction of hyaluronan (HA) and CD44 with the neuronal Wiskott-Aldrich syndrome protein (N-WASP) in regulating actin polymerization and ErbB2/beta-catenin signaling in human ovarian tumor cells (SK-OV-3.ipl cells). Biochemical and immunological analyses indicate that N-WASP is expressed in SK-OV-3.ipl cells and that the binding of HA stimulates N-WASP association with CD44 and Arp2/Arp3 leading to filamentous actin formation and ovarian tumor cell migration. In addition, HA binding promotes CD44-N-WASP association with ErbB2 and activates ErbB2 kinase activity that in turn increases phosphorylation of the cytoskeletal protein, beta-catenin. Subsequently, phosphorylated beta-catenin is transported into the nucleus leading to beta-catenin-mediated TCF/LEF-transcriptional co-activation. Because HA-induced beta-catenin phosphorylation, nuclear translocation, and TCF/LEF transcriptional activation is effectively blocked by the ErbB2 inhibitor, AG825, we conclude that HA/CD44-N-WASP-associated ErbB2 activation is required for beta-catenin-mediated signaling events. Transfection of SK-OV-3.ipl cells with N-WASP-VCA (verpolin homology, cofilin homology, and acidic domain) fragment cDNA not only blocks HA/CD44-induced N-WASP-Arp2/3 complex formation but also inhibits actin polymerization/F-actin assembly and tumor cell migration. Overexpression of the N-WASP-VCA domain also significantly reduces HA-induced ErbB2 recruitment to CD44, diminishes beta-catenin phosphorylation/nuclear translocation, and abrogates TCF/LEF-specific transcriptional co-activation by beta-catenin. Taken together, our findings strongly suggest that N-WASP plays a pivotal role in regulating HA-mediated CD44-ErbB2 interaction, beta-catenin signaling, and actin cytoskeleton functions that are required for tumor-specific behaviors and ovarian cancer progression.
authors.affiliation: Department of Medicine, University of California, Endocrine Unit, Veterans Affairs Medical Center, San Francisco, California 94121, USA. lilly.bourguignon@ucsf.edu
authors.forename: Lilly Y W
authors.initials: LY
authors.lastname: Bourguignon
authors.forename: Karine
authors.initials: K
authors.lastname: Peyrollier
authors.forename: Eli
authors.initials: E
authors.lastname: Gilad
authors.forename: Amy
authors.initials: A
authors.lastname: Brightman
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D010051:Ovarian Neoplasms / Q000378:metabolism* / Q000473:pathology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D015533:Transcriptional Activation / Q000502:physiology; D014162:Transfection; D015854:Up-Regulation / Q000502:physiology; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D000199:Actins; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid; D018719:Erb-b2 Receptor Tyrosine Kinases; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D051176:beta Catenin; C497483:CD44 protein, human; C495770:Wasl protein, rat