By mining DNA microarray data bases at GenBank TM , we identified up-regulation of membrane type 1 matrix metalloproteinase (MT1-MMP) in human primary and metastatic prostate cancer specimens as compared with nonmalignant prostate tissues. To explore the role of up-regulated MT1-MMP in early stage cancer progression, we have employed a three-dimensional cell culture model. Minimally invasive human prostate cancer cells (LNCaP) were transfected with MT1-green fluorescent protein (GFP) chimeric cDNA as compared with GFP cDNA, and morphologic and phenotypic changes were characterized. GFP-expressing LNCaP cells formed multicellular spheroids with cuboidal-like epithelial morphology, whereas MT1-GFP-expressing cells displayed a fibroblast-like morphology and a scattered growth pattern in type I collagen gels. Cell morphologic changes were accompanied by decreased epithelial markers and enhanced mesenchymal markers, consistent with epithelial-to-mesenchymal transition. MT1-MMP-induced morphologic change and cell scattering were abrogated by target inhibition of either the catalytic domain or the hemopexin domain. We further demonstrated that MT1-MMP-induced phenotypic changes were dependent upon up-regulation of Wnt5a, which has been implicated in epithelial-to-mesenchymal transition. We conclude that MT1-MMP plays an important role in early cancer dissemination by converting epithelial cells to migratory mesenchymal-like cells.Most human cancers are epithelial in origin. Carcinoma progression is often accompanied by the loss of an epithelial phenotype and the acquisition of a fibroblastic or mesenchymal phenotype (epithelial-to-mesenchymal transition (EMT) 2 ).This transition has emerged as a critical step in the conversion of early stage cancer to invasive and metastatic cancer (1, 2). Turning an epithelial cell into a mesenchymal cell requires alterations in morphology, cellular architecture, adhesion, and migration. A molecular hallmark of EMT is the decrease or loss of expression of the adherens junction protein, E-cadherin, resulting in loss of cell-cell association and change of cell morphology. Decreased levels of E-cadherin and cytokeratins and acquisition of mesenchymal proteins like fibronectin and vimentin are indicative of a switch toward a mesenchymal dedifferentiated phenotype; these phenotypic changes result in enhanced cell motility and invasiveness (3). Enhanced production and activation of matrix metalloproteinases (MMPs), especially membrane type 1 MMP (MT1-MMP), have been described in most types of carcinoma, including commonly occurring prostate and breast cancer (4). High levels of MMPs in cancer tissues have been correlated with poor prognosis. MMPs have been linked with EMT through both autocrine and/or paracrine pathways (5). Secreted MMPs (e.g. MMP-2, -3, -9, and -28) have been associated with cancer cell EMT through various mechanisms (6 -8). Although MT1-MMP is capable of cleaving E-cadherin in transfected breast cancer cells (9), the effect of this cleavage on EMT has not been characte...

Substrate degradation and cell migration are key steps in cancer metastasis. Membrane-type 1-matrix metalloproteinase (MT1-MMP) has been linked with these processes. Using the fluorescein isothiocyanate (FITC)-labeled fibronectin degradation assay combined with the phagokinetic cell migration assay, structurefunction relationships of MT1-MMP were studied. Our data indicate that MT1-MMP initiates substrate degradation and enhances cell migration; cell migration occurs as a concurrent but independent event. Using recombinant DNA approaches, we demonstrated that the hemopexin-like domain and a nonenzymatic component of the catalytic domain of MT1-MMP are essential for MT1-MMP-mediated cell migration. Because the cytoplasmic domain of MT1-MMP was not required for MT1-MMP-mediated fibronectin degradation and cell migration, it is proposed that cross-talk between the hemopexin domain of MT1-MMP and adjacent cell surface molecules is responsible for outside-in signaling. Employing cDNAs encoding dominant negative mutations, we demonstrated that Rac1 participates in the MT1-MMP signal transduction pathway. These data demonstrated that each domain of MT1-MMP plays a distinct role in substrate degradation and cell migration.Cell migration and invasion are critical coordinated events in the cancer dissemination process (1, 2). Cell migration involves the locomotion of a cell over an extracellular matrix (ECM) 1 substratum (3). Extension of the leading edge is associated with adhesion, i.e. binding of integrins to their ECM ligands leading to subsequent migration and further invasion (4). Cancer cell invasion requires degradation of surrounding ECM and basement membrane by proteinases located at the leading edge of migrating cells. Extracellular proteolytic enzymes, i.e. matrix metalloproteinases (MMPs), serine and cysteine proteinases have long been implicated in cancer metastasis (1, 5).MMPs have been linked to the metastatic phenotype of tumor cells through both correlative and functional studies. Production and activation of MMPs in tumors are required for degradation of the ECM and dissemination of cancer cells to distant organs (2). MMPs also play an important role in tumor angiogenesis (6). The mechanism of activation of latent MMP-2 (pMMP-2) in tumors has been the focus of considerable recent interest based on the identification of a new category of intrinsic membrane-type MMPs (MT1, 2, 3, 4, 5, and 6-MMPs) (7).MT1-MMP is able to activate pMMP-2 on the surface of tumor cells by assembling a unique triplex with tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and pMMP-2; a second MT1-MMP molecule then cleaves the propeptide of pMMP-2, thereby activating the enzyme at the cell surface (8 -10). Integrin receptors, ␣ 3 ␤ 1 and ␣ v ␤ 3 , participate in this response (11). Recombinant MT1-MMP hydrolyze collagen types I, II, and III and digests cartilage proteoglycan, fibronectin, fibrinogen, vitronectin, and laminin (12).It is now recognized that the actions of MMPs are not restricted to the simple breakdown of ECM...

Airway smooth muscle (ASM) proliferation and migration are major components of airway remodeling in asthma. Asthmatic airways are exposed to mechanical strain, which contributes to their remodeling. Matrix metalloproteinase (MMP) plays an important role in remodeling. In the present study, we examined if the mechanical strain of human ASM (HASM) cells contributes to their proliferation and migration and the role of MMPs in this process. HASM were exposed to mechanical strain using the FlexCell system. HASM cell proliferation, migration and MMP release, activation, and expression were assessed. Our results show that cyclic strain increased the proliferation and migration of HASM; cyclic strain increased release and activation of MMP-1, -2, and -3 and membrane type 1-MMP; MMP release was preceded by an increase in extracellular MMP inducer; Prinomastat [a MMP inhibitor (MMPI)] significantly decreased cyclic strain-induced proliferation and migration of HASM; and the strain-induced increase in the release of MMPs was accompanied by an increase in tenascin-C release. In conclusion, cyclic mechanical strain plays an important role in HASM cell proliferation and migration. This increase in proliferation and migration is through an increase in MMP release and activation. Pharmacological MMPIs should be considered in the pursuit of therapeutic options for airway remodeling in asthma.

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