Gene: maps to 11q23 and covers approximately 11 kb (Sirum K.L. and Brinckerhoff C.E., 1989). mRNA: size: ~1.8 kb. Protein: MMP3 can degrade numerous extracellular matrix (ECM) substrates, including collagens III, IV, V, IX, X, and XI, laminins, elastin, entactin, fibronectin, fibrin, fibrillins, fibulin, link protein, osteonectin, tenascin, vitronectin, and ECM proteoglycans. MMP3 can also release cell surface molecules, including E-cadherin, L-selectin, heparin-binding EGF-like growth factor, and TNF-alpha; it can activate other MMPs, including MMP9 and the collagenases; and it can inactivate several serine proteinase inhibitors (Sternlicht M.D. et al., 1999)
See also: structural and functional characteristics of MMPs
Breast cancer
Cell lines:
- Observations suggest that MCF-7 breastt cancer cells (BCC) in culture produce both soluble and membrane-bound factor(s) which stimulate the production of pro-MMPs (including MMP3) and TIMP-1 in neighbouring stromal cells, but the factor(s) released into the medium and that associated with cell membranes are probably different. Such communication between the normal and malignant cell types may, in part, assist the cancer cells to invade and metastasise (Ito A. et al., 1995).
- The expression of c-ets-1 was comparedd with invasiveness in vitro and expression of vimentin, E-cadherin, uPA, MMP-1 and MMP-3 in a panel of human breast cancer cell lines. An association was found between c-ets-1 expression and the invasive, epithelial to mesenchymal transition (EMT)-derived phenotype, which is typified by the expression of vimentin and the lack of E-cadherin. However, no clear quantitative or qualitative relationship between the expression of c-ets-1 and the three proteinases known to be regulated by c-ets-1, except that when they were expressed, it was only in the invasive c-ets-1-positive lines. uPA mRNAs were found in three of the four vimentin-positive lines, MMP-1 in two of the four, and MMP-3 could not be detected in any of the cell lines. Intriguingly, MDA-MB-435 cells, which exhibit the highest metastatic potential of these cell lines in nude mice, expressed vimentin and c-ets-1, but lacked expression of these three proteinases, at least under the culture conditions employed (Gilles C. et al., 1997).
- Epithelial-to-mesenchymal transition ((EMT) is characterized by loss of cell-cell interactions , acquisition of a scattered morphology, downregulation of epithelial cytokeratins and E-cadherin, and upregulation of the mesenchymal marker vimentin. MMP3 may promote EMT in vitro and in vivo, and lead to a premalignant phenotype in mammary epithelial cells (Lochter A. et al., 1997; Sternlicht M.D. et al., 1999).
- To examine MMP-9 activation in a celluular setting, cultures of human tumor cells that were induced to produce MMP-9 over a 200-fold concentration range (0.03 to 8.1 nM) were used. Plasmin, generated by the endogenous plasminogen activator (uPA), is not an efficient activator of proMMP-9. Plasmin, however, is very efficient at generating active MMP-3 from exogenously added proMMP-3. The activated MMP-3, when its concentration exceeds that to TIMP, becomes a potent activator of proMMP-9. Addition to the cultures of already-activated MMP-3 relinquishes the requirement for plasminogen and proMMP-3 additions and results in direct activation of the endogenous proMMP-9. The activated MMP-9 enhances the invasive phenotype of the cultured cells as their ability to transverse basement membrane is significantly increased following zymogen activation (Hahn-Dantona E. et al., 1999).
- Analysis of MMP expression by RT-PCR sshowed expression of MMP-1, MMP-3, and MMP-13 in highly invasive MDA-MB-231 BCC, but not in slightly invasive MCF-7, T-47D, and BT-20 cell lines. The extracellular secretion of MMP-1 and MMP-3 by MDA-MB 231 cells could be also shown by ELISA. TIMP-1 and TIMP-2 mRNAs were found in all cell lines, however, the extracellular secretion of both TIMPs was much higher in MDA-MB-231 cells than in the other cell lines. When the cells were cultured on Matrigel matrix, MMP-9 expression was induced in MDA-MB-231 cells only, as assessed by RT-PCR and zymography experiments. The invasive potential of MDA-MB-231 cells evaluated in vitro through Matrigel was significantly inhibited by the MMP inhibitor BB-2516 (Balduyck M et al., 2000).
Tumors:
- Expression of mRNAs encoding MMP1, MMPP2 and MMP3, and of TIMP1 were studied in human mammary pathology by in situ hybridization and Northern blot analysis. Out of 6 benign lesions, 2 expressed MMP2 mRNAs. mRNAs encoding MMP1 and MMP3 were detectable in occasional stromal and tumor cells in 2 out of 17 carcinomas. Thirteen out of 17 cancers expressed MMP2 mRNA throughout the tumor in stromal cells close to noninvasive tumor clusters and well-differentiated invasive cancer cells. TIMP1 mRNA expression was detected in noninvasive and well-differentiated invasive tumor cells (Polette M. et al., 1993).
- Phenotypically normal mammary epitheliial cells with tetracycline-regulated expression of MMP3 formed epithelial glandular structures in vivo without MMP3 but formed invasive mesenchymal-like tumors with MMP3. Once initiated, the tumors became independent of continued MMP3 expression. MMP3 also promoted spontaneous premalignant changes and malignant conversion in mammary glands of transgenic mice. These changes were blocked by coexpression of a TIMP1 transgene. The premalignant and malignant lesions had stereotyped genomic changes unlike those seen in other murine mammary cancer models. These data indicate that MMP3 influences tumor initiation and alters neoplastic risk (Sternlicht M.D. et al., 1999).
- The expression pattern of MMP-3 was deetermined by in situ hybridization in normal breast tissue (n=6), fibrocystic disease (n=20), five cases of which contained radial scars, lobular carcinoma in situ (CLIS; n=5), ductal carcinoma in situ (DCIS; n=9) and invasive carcinomas (n=24). Tumor cells and peritumor stroma showed low MMP-3 transcript levels, especially in medullary carcinomas (Brummer O. et al., 1999).
- Material from 65 cases of invasive ducctal breast cancer was analyzed by immunohistochemistry for the localization of MMP-2, -3 and -9 and by the non-radioactive in-situ hybridization technique for the localization of the MMP-3-mRNA. A distinct positive immunoreaction for MMP-2, -3 and -9 was observed over both invasive, as well as non-invasive tumor cells, without apparent differences in the staining intensity. There was a significant staining of tumor cell complexes undergoing lymphangiotic dissemination. In addition to this tumor cell staining pattern, a positive immunoreaction, although to reduced proportion, was observed over peritumoral fibroblastic and endothelial stroma cells. Normal breast tissue also revealed a positive immunostaining of epithelial and stromal cells. By in-situ hybridization, mRNA expression for MMP-3 was observed both in tumor and stroma cells, comparable to the protein data. Normal breast epithelia reacted weakly positive for MMP-3-mRNA (Lebeau A. et al., 1999).
- In primary breast cancers, TIMP-1 leveels were found to be weakly but significantly correlated with those for MMP1, proMMP2, active MMP2, MMP3 and proMMP9 (McCarthy K. et al., 1999).
- The expression patterns of MMP-1, -2, and -3 were determined by in situ hybridization in normal breast tissue (n=6), fibrocystic disease (n=20), five cases of which contained radial scars, lobular carcinoma in situ (CLIS; n=5), ductal carcinoma in situ (DCIS; n=9) and invasive carcinomas (n=24). Only a few cells displayed MMP-1- and MMP-2-specific labeling in normal breast tissue and fibrocystic disease. Noninvasive ductal carcinomas showed elevated MMP-2 transcript levels in peritumor stromal cells in the absence of significant MMP-1 specific signals. In general, compared with adjacent normal breast tissue, a gradual increase of MMP-2 was found in noninvasive to invasive cancers. Invasive ductal and lobular carcinomas displayed co-expression of MMP-1 and MMP-2 by stromal cells, mainly of the invasion front, with high signal intensity particularly in high-grade invasive carcinomas. Tumor cells and peritumor stroma showed low MMP-3 transcript levels, especially in medullary carcinomas (Brummer O. et al., 1999).
- Immunoreactivity for MMP3 was detectedd in 22/77 (28.5%) breast carcinomas. MMP3 mRNA was detected in 72/77 (93.5) carcinomas, exclusively in stromal cells within the tumors or in the marginal portion of tumors. MMP3 mRNA was detected more often in ductal carcinomas. MMP3 immunoreactivity in stromal or cancer cells and MMP3 mRNA expression was not associated with menopausal status, histological type or grade, ER, PgR, c-erB-B2 (Nakopoulou L. et al., 1999).
- By substrate zymography, MMP3 was meassured in paired tumour and normal tissue samples from 43 breast cancer patients. Latent MMP3 was more widely expressed in breast tumours than active MMP3. Both latent and active MMP3 were expressed in a significantly greater number of breast tumours when compared with the corresponding normal tissue samples (Garbett E.A. et al., 1999).
References
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