Acquisition of matrix metalloproteinase-2 (MMP-2) activity is temporally associated with increased migration and invasiveness of cancer cells. ProMMP-2 activation requires multimolecular complex assembly involving proMMP-2, membrane type 1-MMP (MT1-MMP, MMP-14), and tissue inhibitor of metalloproteinases-2 (TIMP-2). Because transforming growth factor-β1 (TGF-β1) promotes tumor invasion in advanced squamous cell carcinomas, the role of TGF-β1 in the regulation of MMP activity in a cellular model of invasive oral squamous cell carcinoma was examined. Treatment of oral squamous cell carcinoma cells with TGF-β1 promoted MMP-dependent cell scattering and collagen invasion, increased expression of MMP-2 and MT1-MMP, and enhanced MMP-2 activation. TGF-β1 induced concomitant activation of ERK1/2 and p38 MAPK, and kinase inhibition studies revealed a negative regulatory role for ERK1/2 in modulating acquisition of MMP-2 activity. Thus, a reciprocal effect on proMMP-2 activation was observed whereupon blocking ERK1/2 phosphorylation promoted proMMP-2 activation and MT1-MMP activity, whereas inhibiting p38 MAPK activity decreased proteolytic potential. The cellular mechanism for the control of MT1-MMP catalytic activity involved concurrent reciprocal modulation of TIMP-2 expression by ERK1/2 and p38 MAPKs, such that inhibition of ERK1/2 phosphorylation decreased TIMP-2 production, and down-regulation of p38 MAPK activity enhanced TIMP-2 synthesis. Further, p38 MAPK inhibition promoted ERK1/2 phosphorylation, providing additional evidence for cross-talk between MAPK pathways. These observations demonstrate the complex reciprocal effects of ERK1/2 and p38 MAPK in the regulation of MMP activity, which could complicate the use of MAPK-specific inhibitors as therapeutic agents to down-regulate the biologic effects of TGF-β1 on pericellular collagen degradation and tumor invasion.
This work was supported in part by Grants K08CA94877 (to H. G. M.), R01CA85870 (to M. S. S.), R01CA77816 (to L. C. P.), and R01CA94079 (to L. C. P.) from the NCI, National Institutes of Health, and P01DE12328 (to M. S. S.) from the NIDCR, National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Supported by Grant IRG-93-037-07 from the American Cancer Society to the Robert H. Lurie Comprehensive Cancer Center and by the Zell Family Foundation.
Supported by Grant T32 CA70085 from the National Institutes of Health to the Robert H. Lurie Comprehensive Cancer Center training program in signal transduction and cancer.
