Julie Decock

Matrix metalloproteinases: protective roles in cancer

•  Introduction •  MMP‐3 •  MMP‐8 •  MMP‐9 •  MMP‐12 •  MMP‐19 •  MMP‐26 •  Conclusions

Association of Matrix Metalloproteinase-8 Gene Variation with Breast Cancer Prognosis

Animal and cell studies indicate an inhibitory effect of matrix metalloproteinase-8 (MMP8) on tumorigenesis and metastasis. We investigated whether MMP8 gene variation was associated with breast cancer metastasis and prognosis in humans. We first studied nine tagging single nucleotide polymorphisms (SNP) in the MMP8 gene in 140 clinically and pathologically well-characterized breast cancer patients. Four of the SNPs were found to be associated with lymph node metastasis, the most pronounced being a promoter SNP (rs11225395) with its minor allele (T) associating with reduced susceptibility to lymph node metastasis (P = 0.02). This SNP was further evaluated for association with cancer relapse and survival among a cohort of approximately 1,100 breast cancer patients who had been followed for cancer recurrence and mortality for a median of 7.1 years. The T allele was associated with reduced cancer relapse and greater survival, particularly among patients with earlier stage cancer. Among patients of tumor-node-metastasis stage 0 to II, the adjusted hazard ratio of disease-free survival was 0.7 [95% confidence interval (95% CI), 0.5-0.9] for patients carrying T allele compared with those homozygous for the C allele (P = 0.02). In vitro experiments showed that the T allele had higher promoter activity than the C allele in breast cancer cells. Electrophoretic mobility shift assays showed binding of nuclear proteins to the DNA sequence at the SNP site of the T allele but not that of the C allele. The data suggest that MMP8 gene variation may influence breast cancer prognosis and support the notion that MMP8 has an inhibitory effect on cancer metastasis.

Genetic polymorphisms of matrix metalloproteinases in lung, breast and colorectal cancer

The matrix metalloproteinases (MMPs) can degrade various components of the extracellular matrix and are implicated in the development and progression of cancer. There is evidence suggesting an association of MMP gene polymorphisms with cancer susceptibility and/or metastasis. This paper reviews the findings on several single nucleotide polymorphisms in the collagenase, stromelysin and gelatinase genes in lung cancer, breast cancer and colorectal cancer.

Plasma MMP1 and MMP8 expression in breast cancer: protective role of MMP8 against lymph node metastasis.

BackgroundElevated levels of matrix metalloproteinases have been found to associate with poor prognosis in various carcinomas. This study aimed at evaluating plasma levels of MMP1, MMP8 and MMP13 as diagnostic and prognostic markers of breast cancer.MethodsA total of 208 breast cancer patients, of which 21 with inflammatory breast cancer, and 42 healthy controls were included. Plasma MMP1, MMP8 and MMP13 levels were measured using ELISA and correlated with clinicopathological characteristics.ResultsMedian plasma MMP1 levels were higher in controls than in breast cancer patients (3.45 vs. 2.01 ng/ml), while no difference was found for MMP8 (10.74 vs. 10.49 ng/ml). ROC analysis for MMP1 revealed an AUC of 0.67, sensitivity of 80% and specificity of 24% at a cut-off value of 4.24 ng/ml. Plasma MMP13 expression could not be detected. No correlation was found between MMP1 and MMP8 levels. We found a trend of lower MMP1 levels with increasing tumour size (p = 0.07); and higher MMP8 levels with premenopausal status (p = 0.06) and NPI (p = 0.04). The median plasma MMP1 (p = 0.02) and MMP8 (p = 0.007) levels in the non-inflammatory breast cancer patients were almost twice as high as those found in the inflammatory breast cancer patients. Intriguingly, plasma MMP8 levels were positively associated with lymph node involvement but showed a negative correlation with the risk of distant metastasis. Both controls and lymph node negative patients (pN0) had lower MMP8 levels than patients with moderate lymph node involvement (pN1, pN2) (p = 0.001); and showed a trend for higher MMP8 levels compared to patients with extensive lymph node involvement (pN3) and a strong predisposition to distant metastasis (p = 0.11). Based on the hypothesis that blood and tissue protein levels are in reverse association, these results suggest that MMP8 in the tumour may have a protective effect against lymph node metastasis.ConclusionIn summary, we observed differences in MMP1 and MMP8 plasma levels between healthy controls and breast cancer patients as well as between breast cancer patients. Interestingly, our results suggest that MMP8 may affect the metastatic behaviour of breast cancer cells through protection against lymph node metastasis, underlining the importance of anti-target identification in drug development.

The roles of ADAMTS metalloproteinases in tumorigenesis and metastasis.

The human ADAMTS (a disintegrin and metalloproteinase with thrombospondin-like motifs) family of 19 secreted, multidomain proteolytic enzymes is involved in a wide range of biological processes including ECM assembly and degradation, hemostasis, organogenesis and the regulation of angiogenesis. Defects in certain family members give rise to inherited human genetic diseases, while aberrant expression of other ADAMTSs has been linked to the pathogenesis of arthritis and cancer. Several ADAMTSs act as tumor or metastasis suppressors whose functions are lost either by mutation or epigenetic silencing during tumor progression. This review looks in depth at the involvement of ADAMTSs as positive and negative mediators in cancer growth and spread.

Cathepsin B, cathepsin H, cathepsin X and cystatin C in sera of patients with early-stage and inflammatory breast cancer

Numerous studies have linked cathepsins and their inhibitor cystatin C to tumor invasion and metastasis. We examined whether cathepsin B, cathepsin H, cathepsin X and cystatin C could be detected in sera from women with early stage or inflammatory breast cancer and whether they correlated with clinicopathological characteristics. Preoperative serum was obtained from 176 patients with early-stage breast cancer (tumor size <or= 5 cm, negative lymph nodes) and 31 patients with inflammatory breast cancer. Cathepsin and cystatin C levels were measured by ELISA. The patient and tumor characteristics under study were age at diagnosis, menopausal status, tumor size, tumor grade, and steroid hormone receptor status. Serum cathepsin B levels were significantly lower in patients with poorly differentiated tumors. High cystatin C levels were associated with tumor size, postmenopausal status and patient age. Interestingly, significantly lower levels of cathepsin X and H were found in patients with inflammatory breast cancer, a trend also observed for cathepsin B and cystatin C. In conclusion, our results show a limited association of cathepsins B, H, X and cystatin C with established prognostic parameters. These data are promising and encourage future analysis of the clinical outcome of our patients in order to examine the potential prognostic value of these biomarkers. Further, this study indicates a role for cathepsin X and H in inflammatory breast cancer.

Proteases and metastasis: clinical relevance nowadays?

Purpose of review A great deal of breast cancer research has been devoted to the search for new prognostic and predictive markers which could, on the one hand, enable a more precise identification of patients at high risk of recurrence and, on the other hand, predict the response of each individual patient to the administered therapy. Proteases have been the center of interest because of their prominent involvement in cancer progression and metastasis. In particular, the matrix metalloproteinases, the serine protease urokinase plasminogen activator, the cathepsins, and corresponding inhibitors have been studied extensively. This article reviews the developments during the last year in this field. Recent findings The prognostic effect of urokinase plasminogen activator and plasminogen activator inhibitor 1 was confirmed in a meta-analysis and in a prospective randomized clinical study that provided level 1 evidence for the clinical value of these markers. Furthermore, encouraging data suggest that both urokinase plasminogen activator and plasminogen activator inhibitor 1 might be important predictive markers. To date, findings on the prognostic and predictive value of the matrix metalloproteinases, the cathepsins, and their inhibitors are still inconclusive. Summary On the basis of currently available data, tumor urokinase plasminogen activator and plasminogen activator inhibitor 1 levels could already be used in everyday clinical practice for selection of candidates for adjuvant systemic therapy. Further effort should be put into the standardization of the matrix metalloproteinases and cathepsins determination so that their clinical relevance in breast cancer can be defined.

Matrix Metalloproteinase 8 (Collagenase 2) Induces the Expression of Interleukins 6 and 8 in Breast Cancer Cells

Background: Matrix metalloproteinase 8 is a metastasis-suppressing metalloprotease that regulates neutrophil chemotaxis in inflammation. Results: MMP-8 expression by breast cancer cells is deleterious to long-term growth, but it induces IL-6 and IL-8, factors that conventionally promote malignancy. Conclusion: MMP-8 influences signaling that regulates expression of proinflammatory factors. Significance: These effects may contribute to how MMP-8 controls the onset and resolution of inflammation. Matrix metalloproteinase 8 (MMP-8) is a tumor-suppressive protease that cleaves numerous substrates, including matrix proteins and chemokines. In particular, MMP-8 proteolytically activates IL-8 and, thereby, regulates neutrophil chemotaxis in vivo. We explored the effects of expression of either a WT or catalytically inactive (E198A) mutant version of MMP-8 in human breast cancer cell lines. Analysis of serum-free conditioned media from three breast cancer cell lines (MCF-7, SK-BR-3, and MDA-MB-231) expressing WT MMP-8 revealed elevated levels of IL-6 and IL-8. This increase was mirrored at the mRNA level and was dependent on MMP-8 catalytic activity. However, sustained expression of WT MMP-8 by breast cancer cells was non-permissive for long-term growth, as shown by reduced colony formation compared with cells expressing either control vector or E198A mutant MMP-8. In long-term culture of transfected MDA-MB-231 cells, expression of WT but not E198A mutant MMP-8 was lost, with IL-6 and IL-8 levels returning to base line. Rare clonal isolates of MDA-MB-231 cells expressing WT MMP-8 were generated, and these showed constitutively high levels of IL-6 and IL-8, although production of the interleukins was no longer dependent upon MMP-8 activity. These studies support a causal connection between MMP-8 activity and the IL-6/IL-8 network, with an acute response to MMP-8 involving induction of the proinflammatory mediators, which may in part serve to compensate for the deleterious effects of MMP-8 on breast cancer cell growth. This axis may be relevant to the recognized ability of MMP-8 to orchestrate the innate immune system in inflammation in vivo.

Metalloproteinase-Dependent and -Independent processes contribute to inhibition of breast cancer cell migration, angiogenesis and liver metastasis by a disintegrin and metalloproteinase with thrombospondin motifs-15

The ADAMTS proteinases are a family of secreted, matrix‐associated enzymes that have diverse roles in the regulation of tissue organization and vascular homeostasis. Several of the 19 human family members have been identified as having either tumor promoting or suppressing roles. We previously demonstrated that decreased ADAMTS15 expression correlated with a worse clinical outcome in mammary carcinoma (e.g., Porter et al., Int J Cancer 2006;118:1241–7). We have explored the effects of A Disintegrin and Metalloproteinase with Thrombospondin motifs‐15 (ADAMTS‐15) on the behavior of MDA‐MB‐231 and MCF‐7 breast cancer cells by stable expression of either a wild‐type (wt) or metalloproteinase‐inactive (E362A) protein. No effects on mammary cancer cell proliferation or apoptosis were observed for either form of ADAMTS‐15. However, both forms reduced cell migration on fibronectin or laminin matrices, though motility on a Type I collagen matrix was unimpaired. Knockdown of syndecan‐4 attenuated the inhibitory effects of ADAMTS‐15 on cell migration. In contrast to its effects on cell migration, wt ADAMTS‐15 but not the E362A inactive mutant inhibited endothelial tubulogenesis in 3D collagen gels and angiogenesis in the aortic ring assay. In experimental metastasis assays in nude mice, MDA‐MB‐231 cells expressing either form of ADAMTS‐15 showed reduced spread to the liver, though lung colonization was enhanced for cells expressing wt ADAMTS‐15. These studies indicate that extracellular ADAMTS‐15 has multiple actions on tumor pathophysiology. Via modulation of cell‐ECM interactions, which likely involve syndecan‐4, it attenuates mammary cancer cell migration independent of its metalloproteinase activity; however, its antiangiogenic action requires catalytic functionality, and its effects on metastasis in vivo are tissue niche‐dependent.

TGF-β-Elicited Induction of Tissue Inhibitor of Metalloproteinases (TIMP)-3 Expression in Fibroblasts Involves Complex Interplay between Smad3, p38α, and ERK1/2

Transforming growth factor-β (TGF-β) promotes extracellular matrix deposition by down-regulating the expression of matrix degrading proteinases and upregulating their inhibitors. Tissue inhibitor of metalloproteinases (TIMP)-3 is an ECM-associated specific inhibitor of matrix degrading metalloproteinases. Here, we have characterized the signaling pathways mediating TGF-β-induced expression of TIMP-3. Basal and TGF-β-induced TIMP-3 mRNA expression was abolished in Smad4-deficient mouse embryonic fibroblasts and restoring Smad4 expression rescued the response. Inhibition of Smad signaling by expression of Smad7 and dominant negative Smad3 completely abolished TGF-β-elicited expression of TIMP-3 in human fibroblasts, whereas overexpression of Smad3 enhanced it. Inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activation with PD98059 and p38 mitogen-activated protein kinase activity by SB203580 resulted in suppression of TGF-β-induced TIMP-3 expression, indicating that ERK1/2 and p38 MAPK mediate the effect of TGF-β on TIMP-3 expression. Specific activation of p38α and ERK1/2 by constitutively active mutants of MKK3b or MEK1, respectively, and simultaneous co-expression of Smad3 resulted in induction of TIMP-3 expression in the absence of TGF-β indicating that Smad3 co-operates with p38 and ERK1/2 in the induction of TIMP-3 expression. These results demonstrate the complex interplay between Smad3, p38α, and ERK1/2 signaling in the regulation of TIMP-3 gene expression in fibroblasts, which may play a role in inflammation, tissue repair, and fibrosis.