Inhibition of prostate cancer cell invasion by targeting the different domains of membrane type 1-matrix metalloproteinase (MT1-MMP)

Abstract

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Extracellular matrix (ECM) degradation and cell migration are key steps for initiation of malignant cell invasion and metastasis. MT1-MMP has been linked with those processes by digesting ECM components and promoting cell migration. We recently demonstrated that the catalytic domain and hemopexin (PEX) domain of MT1-MMP play a distinct role in terms of substrate degradation and cell migration, respectively (Cao et al. J. Biol. Chem., 2004). By employing a three-dimensional (3D) culture system and cancer cell lines stably expressing MT1-MMP-Green Fluorescent Protein chimera (MT1-GFP) or GFP control, we now present evidence that MT1-MMP induces cancer cell scattering in 3D type I collagen matrices and this cell growth pattern is completely abolished by inhibiting either the catalytic domain or the PEX domain of MT1-MMP. LNCaP human prostate cancer cells stably transfected with MT1-GFP chimeric cDNA presented a scattering growth pattern in 3D type I collagen matrices as compared with spherical aggregates of LNCaP cells expressing GFP control. Inhibition of enzymatic activity of MT1-MMP by the synthetic hydroxamate inhibitor (CT1748) or TIMP-2, but not TIMP-1 interfered with MT1-MMP-induced cell scattering resulting in formation of cell aggregates. Cells expressing constitutively inactive MT1-MMP (MT1E240-A-GFP chimera) behaved like GFP-expressing cells emphasizing the essential role of enzymatic activity of MT1-MMP in cancer cell invasion. We previously demonstrated that an antibody against the PEX domain of MT1-MMP efficiently blocked MT1-MMP-induced LNCaP cell migration in 2D culture system. To evaluate the effect of the inhibitory antibody on MT1-MMP-induced cell scattering in the 3D collagen type I matrices, the antibody was added into the test system. Cell scattering induced by MT1-MMP was inhibited by the antibody against the PEX domain of MT1-MMP. The same inhibitory effect targeting either the catalytic domain or the PEX domain of MT1-MMP was found with human breast cancer MCF-7 cells stably transfected with MT1-GFP chimeric cDNA. Taken together, our data emphasize that ECM degradation and cell migration are critical aspects for MT1-MMP-induced cancer cell invasion. Targeting either the catalytic core structure or the PEX domain of MT1-MMP will result in interference with MT1-MMP-induced cancer cell invasion.