title: Enhanced invasion and tumor growth of fibroblast growth factor 8b-overexpressing MCF-7 human breast cancer cells.
abstract: Fibroblast growth factor 8 (FGF-8) is a secreted heparin-binding protein, which has mitogenic and transforming activity. Increased expression of FGF-8 has been found in human breast cancer, and it has a potential autocrine role in its progression. Human FGF-8 is alternatively spliced to generate four protein isoforms (a, b, e, and f). Isoform b has been shown to be the most transforming. In this work, we studied the role of FGF-8b in the growth (in vitro and in vivo) of MCF-7 human breast cancer cells, which proliferate in an estrogen-dependent manner. Constitutive overexpression of FGF-8b in MCF-7 cells down-regulated FGF-8b-binding receptors FGF receptor (FGFR) 1IIIc, FGFR2IIIc, and FGFR4 found to be expressed in these cells. FGF-8b overexpression led to an increase in the anchorage-independent proliferation rate in suspension culture and colony formation in soft agar, when MCF-7 cells were cultured with or without estradiol. FGF-8b also provided an additional growth advantage for cells stimulated with estradiol. In addition, FGF-8b-transfected cells invaded more actively through Matrigel than did control cells. This was possibly due to the increased secretion of matrix metalloproteinase 9. In vivo, FGF-8b-transfected MCF-7 cells formed faster growing tumors than vector-only-transfected cells when xenografted into nude mice. The tumors formed by FGF-8b-transfected cells were more vascular than the tumors formed by vector-only-transfected cells. In conclusion, FGF-8b expression confers a growth advantage to MCF-7 breast carcinoma cells, both in vitro and in vivo. In addition to stimulation of proliferation, this growth advantage probably arises from increased invasion and tumor vascularization induced by FGF-8b. The results suggest that FGF-8b signaling may be an important factor in the regulation of tumorigenesis and progression of human breast cancer.
authors.affiliation: Department of Anatomy, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: J K
authors.initials: JK
authors.lastname: Ruohola
authors.forename: T P
authors.initials: TP
authors.lastname: Viitanen
authors.forename: E M
authors.initials: EM
authors.lastname: Valve
authors.forename: J A
authors.initials: JA
authors.lastname: Seppänen
authors.forename: N T
authors.initials: NT
authors.lastname: Loponen
authors.forename: J J
authors.initials: JJ
authors.lastname: Keskitalo
authors.forename: P T
authors.initials: PT
authors.lastname: Lakkakorpi
authors.forename: P L
authors.initials: PL
authors.lastname: Härkönen
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D002448:Cell Adhesion / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D005260:Female; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000378:metabolism; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D017468:Receptors, Fibroblast Growth Factor / Q000096:biosynthesis / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014183:Transplantation, Heterologous
chemical_list: C496456:FGF8 protein, human; C496457:Fgf8 protein, mouse; D020033:Protein Isoforms; D017468:Receptors, Fibroblast Growth Factor; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors