title: Tissue inhibitor of metalloproteinase-1 protects human breast epithelial cells against intrinsic apoptotic cell death via the focal adhesion kinase/phosphatidylinositol 3-kinase and MAPK signaling pathway.
abstract: Tissue inhibitor of metalloproteinase (TIMP-1) is a natural protease inhibitor of matrix metalloproteinases (MMPs). Recent studies revealed a novel function of TIMP-1 as a potent inhibitor of apoptosis in mammalian cells. However, the mechanisms by which TIMP-1 exerts its anti-apoptotic effect are not understood. Here we show that TIMP-1 activates cell survival signaling pathways involving focal adhesion kinase, phosphatidylinositol 3-kinase, and ERKs in human breast epithelial cells to TIMP-1. TIMP-1-activated cell survival signaling down-regulates caspase-mediated classical apoptotic pathways induced by a variety of stimuli including anoikis, staurosporine exposure, and growth factor withdrawal. Consistently, down-regulation of TIMP-1 expression greatly enhances apoptotic cell death. In a previous study, substitution of the second amino acid residue threonine for glycine in TIMP-1, which confers selective MMP inhibition, was shown to obliterate its anti-apoptotic activity in activated hepatic stellate cells suggesting that the anti-apoptotic activity of TIMP-1 is dependent on MMP inhibition. Here we show that the same mutant inhibits apoptosis of human breast epithelial cells, suggesting different mechanisms of TIMP-1 regulation of apoptosis depending on cell types. Neither TIMP-2 nor a synthetic MMP inhibitor protects breast epithelial cells from intrinsic apoptotic cell death. Furthermore, TIMP-1 enhances cell survival in the presence of the synthetic MMP inhibitor. Taken together, the present study unveils some of the mechanisms mediating the anti-apoptotic effects of TIMP-1 in human breast epithelial cells through TIMP-1-specific signal transduction pathways.
authors.affiliation: Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
authors.forename: Xu-Wen
authors.initials: XW
authors.lastname: Liu
authors.forename: M Margarida
authors.initials: MM
authors.lastname: Bernardo
authors.forename: Rafael
authors.initials: R
authors.lastname: Fridman
authors.forename: Hyeong-Reh Choi
authors.initials: HR
authors.lastname: Kim
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D001940:Breast / Q000166:cytology* / Q000378:metabolism*; D002470:Cell Survival; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D020935:MAP Kinase Signaling System; D061965:Matrix Metalloproteinase Inhibitors; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D061965:Matrix Metalloproteinase Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human