title: ALK5 promotes tumor angiogenesis by upregulating matrix metalloproteinase-9 in tumor cells.
abstract: Transforming growth factor beta 1 (TGF-beta1) is a potent tumor suppressor but, paradoxically, TGF-beta1 enhances tumor growth and metastasis in the late stages of cancer progression. This study investigated the role of TGF-beta type I receptor, ALK5, and three mitogen-activated protein kinases (MAPKs) in metastasis by breast cancer cell line MDA-MB-231. We show that autocrine TGF-beta signaling in MDA-MB-231 cells is required for tumor cell invasion and tumor angiogenesis. Expression of kinase-inactive ALK5 reduces tumor invasion and formation of new blood vessels within the tumor orthotopic xenografts in severe combined immunodeficiency (SCID) mice. In contrast, constitutively active ALK5-T204D enhances tumor invasion and angiogenesis by stimulating expression of matrix metalloproteinase MMP-9/gelatinase-B. Ablation of MMP-9 in ALK5-T204D cells by RNA interference (RNAi) reduces tumor invasion and tumor growth. Importantly, RNAi-MMP-9 reduces tumor neovasculature and increases tumor cell death. Induction of MMP-9 by TGF-beta-ALK5 signaling requires MEK-ERK but not JNK, p38 MAPK or Smad4. Dominant-negative MEK blocks and constitutively active MEK1 enhances MMP-9 expression. However, all three MAPK cascades (ERK, JNK and p38 MAPK) are required for TGF-beta-mediated cell migration. Collectively, our results show that TGF-beta-ALK5-MAPK signaling in tumor cells promotes tumor angiogenesis and MMP-9 is an important component of this program.
authors.affiliation: Department of Cancer Genetics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: A
authors.initials: A
authors.lastname: Safina
authors.forename: E
authors.initials: E
authors.lastname: Vandette
authors.forename: A V
authors.initials: AV
authors.lastname: Bakin
mesh_terms: D030201:Activin Receptors, Type I / Q000502:physiology*; D000818:Animals; D001943:Breast Neoplasms / Q000098:blood supply / Q000201:enzymology* / Q000473:pathology*; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis* / Q000235:genetics*; D051379:Mice; D016513:Mice, SCID; D009361:Neoplasm Invasiveness; D009389:Neovascularization, Pathologic / Q000201:enzymology*; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D053773:Transforming Growth Factor beta1 / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology*
chemical_list: D018125:Receptors, Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human; C000625842:Tgfbr1 protein, mouse; D020780:Matrix Metalloproteinase 9