title: Up-regulation of Flotillin-2 is associated with melanoma progression and modulates expression of the thrombin receptor protease activated receptor 1.
abstract: Flotillin 2 (flot-2) is a highly conserved protein isolated from caveolae/lipid raft domains that tether growth factor receptors linked to signal transduction pathways. Flot-2 protein and mRNA were increased in tumorigenic and metastatic melanoma cell lines in vitro, and the immunostaining intensity increased substantially across a tissue array of melanocytic lesions. Flot-2 transfection transformed SB2 melanoma cells from nontumorigenic, nonmetastatic to highly tumorigenic and metastatic in a nude mouse xenograft model. SB2 cells stably transfected with the flot-2 cDNA (SB2-flot)-2 cells proliferated faster in the absence of serum, and their migration through Matrigel was additionally enhanced by thrombin. When SB2-flot-2 cells were compared with SB2-vector-control cells on a cancer gene pathway array, SB2-flot-2 cells had increased expression of protease activated receptor 1 (PAR-1) mRNA, a transmembrane, G-protein-coupled receptor involved in melanoma progression. PAR-1 and flot-2 were coimmunoprecipitated from SB2-flot-2 cells. Up-regulation of PAR-1 was additionally confirmed in SB2-flot-2 cells and melanoma cell lines. SB2-flot-2 cells transfected with flot-2-specific small-interfering RNAs made substantially less flot-2 and PAR-1 mRNA. In conclusion, flot-2 overexpression is associated with melanoma progression, with increased PAR-1 expression, and with transformation of SB2 melanoma cells to a highly metastatic line. Flot-2 binds to PAR-1, a known upstream mediator of major signal transduction pathways implicated in cell growth and metastasis, and may thereby influence tumor progression.
authors.affiliation: Department of Dermatology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Parul
authors.initials: P
authors.lastname: Hazarika
authors.forename: Marya F
authors.initials: MF
authors.lastname: McCarty
authors.forename: Victor G
authors.initials: VG
authors.lastname: Prieto
authors.forename: Saira
authors.initials: S
authors.lastname: George
authors.forename: Daniel
authors.initials: D
authors.lastname: Babu
authors.forename: Dimpy
authors.initials: D
authors.lastname: Koul
authors.forename: Menashe
authors.initials: M
authors.lastname: Bar-Eli
authors.forename: Madeleine
authors.initials: M
authors.lastname: Duvic
mesh_terms: D000818:Animals; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000235:genetics; D018450:Disease Progression; D006801:Humans; D008297:Male; D008545:Melanoma / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D044463:Receptor, PAR-1 / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection; D015854:Up-Regulation
chemical_list: D018076:DNA, Complementary; D008565:Membrane Proteins; D012333:RNA, Messenger; D044463:Receptor, PAR-1; C106354:flotillins