A novel small molecule, SR 13179, decreases gelatinase activity in breast carcinoma cells through induction of TIMP-2 protein: A possible mechanism for its anti-invasive and anti-tumor activity

Abstract

2339

Tissue inhibitor of metalloproteinase-2 (TIMP-2) is known to play a role in the inhibition of tumor invasion and angiogenesis by blocking the activation of pro-MMP-2 (progelatinase) by MT1-MMP, a process regulated by binding of TIMP-2 with MT1-MMP. However, recent data suggest that the antiangiogenic and antitumor effects of TIMP-2 may also occur through MMP-independent mechanisms such as inactivation of some growth signaling pathways. Overexpression of TIMP-2 or adenovirus-mediated TIMP-2 therapy has shown to significantly inhibit tumor growth, angiogenesis and metastasis in animal models. Development of small molecule therapeutic agents that increase cellular TIMP-2 levels therefore offer a new molecular-targeted approach to anti-angiogenic and anti-metastatic treatment of cancer. We report the discovery of a novel class of small molecules, of which SR 13179 is a lead compound, that inhibit the invasion of highly metastatic human breast cancer cell lines MCF10CA1a and MDA-MB-231, at doses that do not affect migration or cell viability. We show that SR 13179 inhibits the gelatinolytic activity of MMP-2 by >50% in zymography experiments. SR 13179 has no effect on the expression of MMP-2 or MT1-MMP protein or mRNA, but instead increased protein levels of TIMP-2 by 5-fold after 48 h. SR 13179 has potent antitumor activity in several tumor cell lines regardless of their hormone receptor, p53 or multi-drug resistance status. SR 13179 also possesses potent anti-angiogenic activity in the chorioallantoic membrane (CAM) assay. Since TIMP-2 is a multifunctional molecule with inhibitory effects on tumor growth, metastasis and angiogenesis, it is likely that the increase in TIMP-2 protein levels by SR 13179 plays a central role in the anti-tumor, anti-invasive and anti-angiogenic activity of this novel small molecule. These activities can be mediated through MMP-dependent as well as MMP-independent growth signaling pathways. The results of these mechanistic studies with SR 13179 will be presented. These studies were partly supported by the DoD Breast Cancer Research Program grant (DAMD 17-03-1-0587 to NZ).