Direct cell-cell interaction enhances pro-MMP-2 production and activation in co-culture of laryngeal cancer cells and fibroblasts: involvement of EMMPRIN and MT1-MMP.

Matrix metalloproteinases-2 (MMP-2, gelatinase A) has been regarded as a crucial enzyme for tumor progression, invasion, and metastasis by its capability to degrade the basement membrane components, and its activation process is critical for tumor development. Recently, EMMPRIN/CD147, which is a member of immunoglobulin superfamily, has been reported to be highly expressed in tumor cells and induce production of MMPs from fibroblasts adjacent to the tumor cells. In this study, we demonstrated that production of pro- and active forms of MMP-2 by human dermal fibroblasts was enhanced by the direct cell-cell contact with co-cultured HEp-2 cells derived from a human laryngeal epidermoid carcinoma. The results from immunoblotting and reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated that HEp-2 cells express a higher level of EMMPRIN but only a low level of MMP-2 and membrane type 1-matrix metalloproteinase (MT1-MMP), whereas fibroblasts express a higher level of MMP-2 and MT1-MMP and a low level of EMMPRIN. In a mixed co-culture with direct cell-cell contacts, co-cultured HEp-2 cells stimulated the pro- and active MMP-2 production from fibroblasts, but not in a separated co-culture through polycarbonate membrane. Production of pro/active MMP-2 and MT1-MMP (activator of pro-MMP-2) in fibroblasts was induced by the addition of membrane fractions prepared from HEp-2 cells to the fibroblast culture, and the induction was suppressed by the EMMPRIN depletion after immunoprecipitation, signifying the participation of EMMPRIN for the induction and activation of MMP-2. Our results suggest an importance of the direct cell-cell interaction involving EMMPRIN rather than humoral factors such as cytokines for pro-MMP-2 production and activation followed by tumor progression, invasion, and metastasis in laryngeal cancer.