title: Hypoxia stimulates breast carcinoma cell invasion through MT1-MMP and MMP-2 activation.
abstract: The process of cancer cell invasion involves degradation of the extracellular matrix (ECM) by proteases, integrin adhesion and cell motility. The role of ECM degrading proteases on the hypoxia-induced invasion of breast carcinoma cells was investigated. Hypoxia markedly increased the invasion capacity of MDA-MB-231 and MDA-MB-435 breast carcinoma cell lines. Matrix metalloproteinase (MMP) inhibitors blocked the hypoxia-induced invasion, whereas other protease inhibitors had no effect. Antibodies or siRNAs blocking either membrane type-1 MMP (MT1-MMP) or MMP-2 were effective in reducing the hypoxia-induced invasion. Serum-free reconstitution experiments confirmed the involvement of the MT1-MMP/MMP-2/tissue inhibitor of metalloproteinase-2 complex in this hypoxia-induced response. Overexpression of MT1-MMP in a poorly invasive breast cancer cell line, T47-D, promoted hypoxia-induced invasion and MMP-2 activation. Cell surface accumulation and activation of MT1-MMP without apparent regulation at the mRNA or protein levels indicated a post-translational adaptive response to hypoxia. Inhibition of the small GTPase RhoA eliminated the hypoxia-induced invasion and blocked the localization of MT1-MMP to the plasma membrane. Zymographic and molecular analysis of human breast tumors showed a strong correlation between hypoxic microenvironments and MMP-2 activation without changes in MT1-MMP expression. Our studies suggest that hypoxic tumor microenvironments promote breast cancer invasion through an MT1-MMP-dependent mechanism.
authors.affiliation: Center for Vascular Biology, University of Connecticut Health Center, Farmington, CT 06030-3501, USA.
authors.forename: U M
authors.initials: UM
authors.lastname: Muñoz-Nájar
authors.forename: K M
authors.initials: KM
authors.lastname: Neurath
authors.forename: F
authors.initials: F
authors.lastname: Vumbaca
authors.forename: K P
authors.initials: KP
authors.lastname: Claffey
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000502:physiology*; D020782:Matrix Metalloproteinases / Q000502:physiology*; D053504:Matrix Metalloproteinases, Membrane-Associated; D009361:Neoplasm Invasiveness; D034622:RNA Interference; D012333:RNA, Messenger / Q000032:analysis; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000502:physiology; D020742:rhoA GTP-Binding Protein / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D019716:Tissue Inhibitor of Metalloproteinase-2; D020782:Matrix Metalloproteinases; D053504:Matrix Metalloproteinases, Membrane-Associated; D020778:Matrix Metalloproteinase 2; D020742:rhoA GTP-Binding Protein