IMMUNOHISTOCHEMICAL LOCALIZATION OF MATRIX METALLOPROTEINASE 2 AND ITS SPECIFIC INHIBITOR TIMP-2 IN NEOPLASTIC TISSUES WITH MONOCLONAL-ANTIBODIES

Matrix metalloproteinase-2 (MMP-2), synthesized as a 631 amino-acid pr oenzyme, is activated by cleavage of the first 80 amino acids and natu rally inhibited by tissue inhibitor of metalloproteinase-2 (TIMP-2). W e report here the production of MAbs against MMP-2 and TIMP-2 and thei r use in localizing the respective antigens on tumor tissues. The anti -MMP-2 MAb recognized the latent and activated MMP-2 mutant protein (m utein) with C-terminal deletion at amino acid 425, indicating that bot h N- and C-terminal amino acids of MMP-2 are not important for its bin ding. The binding study of anti-TIMP-2 MAb, using several C-terminally truncated TIMP-2 muteins, showed that the amino acids I I 1- 126 of T IMP-2 are essential for the binding of this antibody, Besides their re spective antigens, both MAbs also recognized the MMP-2/TIMP-2 complex. On frozen sections of breast tumor, anti-MMP-2 MAb stained mainly tum or-cell cytoplasm with varying intensity, while anti-TIMP-2 MAb gave a stromal staining of varying intensity and a weak or absent staining o f tumor-cell cytoplasm, suggesting different localization of the prote ins in these tumors. In addition, in 1/3 of the breast cases both anti bodies also localized on tumor-cell membranes. Similar cytoplasmic and stromal but not membrane staining patterns were observed in colon, ga stric, endometrial, squamous-cell, prostatic and ovarian carcinoma as well. Since MMP-2 degrades type-IV collagen, the major component of ba sement membranes, the differences between MMP-2 and TIMP-2 levels and localization in individual tumors may relate to the invasiveness of th e tumor and thus provide predictive information. However, this aspect could not be discussed in this study because no biological and clinica l parameters such as lymph-node involvement or Dukes' stage of the tum ors were available. (C) Wiley-Liss, Inc.