Tissue inhibitor of metalloproteinases-2 (TIMP-2) suppresses TKR-growth factor signaling independent of metalloproteinase inhibition

The tissue inhibitors of metalloproteinases (TIMPs) block matrix metallopro teinase (MMP)-mediated increases in cell proliferation, migration, and inva sion that are associated with extracellular matrix (ECM) turnover. Here we demonstrate a direct role for TIMP-2 in regulating tyrosine kinase-type gro wth factor receptor activation. We show that TIMP-2 suppresses the mitogeni c response to tyrosine kinase-type receptor growth factors in a fashion tha t is independent of MMP inhibition. The TIMP-2 suppression of mitogenesis i s reversed by the adenylate cyclase inhibitor SQ22536, and implicates cAMP as the second messenger in these effects. TIMP-2 neither altered the releas e of transforming growth factor alpha from the cell surface, nor epidermal growth factor (EGF) binding to the cognate receptor, EGFR, TIMP-2 binds to the surface of AS49 cells in a specific and saturable fashion (K-d = 147 pM ), that is not competed by the synthetic MMP inhibitor BB-94 and is indepen dent of MT-1-MMP. TIMP-2 induces a decrease in phosphorylation of EGFR and a concomitant reduction in Grb-2 association. TIMP-2 prevents SH2-protein-t yrosine phosphatase-l (SHP-1) dissociation from immunoprecipitable EGFR com plex and a selective increase in total SHP-1 activity. These studies repres ent a new functional paradigm for TIMP-2 in which TIMP suppresses EGF-media ted mitogenic signaling by short-circuiting EGFR activation.