title: Hepatocyte growth factor/scatter factor induces feedback up-regulation of CD44v6 in melanoma cells through Egr-1.
abstract: The hepatocyte growth factor/scatter factor (HGF/SF) receptor c-Met and variants of the CD44 family of surface adhesion molecules, including CD44v6, have been implicated in cancer progression and metastasis. CD44 isoforms bearing heparin sulfate chains can bind to HGF/SF and facilitate its presentation to c-Met. Here, we demonstrate that HGF/SF-Met binding up-regulates the expression of CD44v6 in murine melanoma cells, serving to compensate for loss by internalization. c-Met-mediated CD44v6 up-regulation was achieved through transcriptional activation of the immediate early gene egr-1. Enhanced egr-1 expression was apparent at the level of RNA 40 min after exposure to HGF/SF, and Egr-1 protein was detectable between 1 and 2 h post-treatment. CD44v6 RNA levels were correspondingly elevated 2 h after HGF/SF exposure. HGF/SF induced egr-1 activation via the Ras>Erk1/2 pathway but not through either phosphatidylinositol 3'-kinase or protein kinase C. Binding of NK2, a naturally occurring splice variant of HGF/SF, to c-Met failed to induce either Egr-1 or CD44v6, accounting at least in part for its antagonistic behavior. We also identified an Egr-1-binding site in the mouse CD44 gene promoter that accounts for its responsiveness to HGF/SF in melanoma cells. The compensatory up-regulation of both c-Met and CD44v6 in response to HGF/SF has important implications with respect to strategies used by cancer cells to sustain stimulation of growth- and metastasis-promoting pathways associated with tumor progression.
authors.affiliation: Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4264, USA.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Recio
authors.forename: Glenn
authors.initials: G
authors.lastname: Merlino
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051766:Early Growth Response Protein 1; D005246:Feedback / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D017228:Hepatocyte Growth Factor / Q000502:physiology*; D018960:Hyaluronan Receptors / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D017874:Immediate-Early Proteins; D020935:MAP Kinase Signaling System / Q000276:immunology; D008546:Melanoma, Experimental / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D019859:Proto-Oncogene Proteins c-met / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D015854:Up-Regulation
chemical_list: C112697:CD44v6 antigen; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D006023:Glycoproteins; D018960:Hyaluronan Receptors; D017874:Immediate-Early Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases