Gelatinases have been shown to play a key role in angiogenesis and tumor metastasis. Small molecular weight synthetic inhibitors for these enzymes are highly sought for potential use as anti-metastatic agents. Virtually all of the known inhibitors of matrix metalloproteinases (MMPs) are broad spectrum. We report herein the synthesis and kinetic characterization of two compounds, 4-(4-phenoxyphenylsulfonyl)butane-1,2-dithiol (compound 1) and 5-(4-phenoxyphenylsulfonyl)pentane-1,2-dithiol (compound 2), that are potent and selective gelatinase inhibitors. These compounds are slow, tightbinding inhibitors of gelatinases (MMP-2 and MMP-9) with K i values in the nanomolar range. In contrast, competitive inhibition of the catalytic domain of membranetype 1 metalloproteinase (MMP-14 cat ) with comparable K i values (K i ϳ200 nM) was observed. Binding to stromelysin (MMP-3) was substantially weaker, with K i values in the micromolar range (K i ϳ10 M). No binding to matrilysin (MMP-7) and collagenase 1 (MMP-1) was detected at inhibitor concentrations up to 60 M. We have previously shown that synthetic MMP inhibitors work synergistically with TIMP-2 in the promotion of pro-MMP-2 activation by MT1-MMP in a process that depends on the affinity of the inhibitor toward MT1-MMP. It is shown herein that the dithiols are significantly less efficient (>100-fold) than marimastat, a broad-spectrum MMP inhibitor, in enhancing pro-MMP-2 activation in cells infected to express MT1-MMP, consistent with the lower affinity of the dithiols toward MT1-MMP. Thus, in contrast to broad-spectrum MMP inhibitors, the dithiols are less likely to promote MT1-MMP-dependent pro-MMP-2 activation in the presence of TIMP-2, while maintaining their ability to inhibit active MMP-2 effectively.
Matrix metalloproteinases (MMPs)1 are zinc-dependent endopeptidases known to play key roles in normal and pathological conditions involving remodeling and turnover of extracellular matrix, such as embryonic development, wound healing, angiogenesis, arthritis, cardiovascular diseases, and cancer. In cancer, MMPs are known to be required at all stages of tumorigenesis, including tumor establishment and growth, neovascularization, intravasation, extravasation, and metastasis (1, 2). MMPs are expressed as zymogenic latent enzymes. The zymogenic form has a propeptide that achieves coordination to the catalytic zinc ion by a strictly conserved cysteine residue (for a comparative review of MMP structures see Ref.3). MMP activation occurs when the cysteine thiolate-zinc ion coordination is broken, usually as a consequence of two proteolytic cleavages of the propeptide, either by autolysis or by hydrolytic action of other proteinases (4 -6). MMPs are inhibited by the tissue inhibitors of metalloproteinases (TIMPs), a family of four proteins that are the natural inhibitors of MMPs.A subgroup of the MMP family, gelatinases A and B (MMP-2 and MMP-9, respectively), has been shown to play a key role in angiogenesis and tumor metastasis (7, 8). MMP-2 has been the subject of intens...