Molecular Mechanisms Driven by MT4-MMP in Cancer Progression

MT4-MMP (or MMP-17) belongs to the membrane-type matrix metalloproteinases (MT-MMPs), a distinct subset of the MMP family that is anchored to the cell surface, in this case by a glycosylphosphatidylinositol (GPI) motif. Its expression in a variety of cancers is well documented. However, the molecular mechanisms by which MT4-MMP contributes to tumor development need further investigation. In this review, we aim to summarize the contribution of MT4-MMP in tumorigenesis, focusing on the molecular mechanisms triggered by the enzyme in tumor cell migration, invasiveness, and proliferation, in the tumor vasculature and microenvironment, as well as during metastasis. In particular, we highlight the putative substrates processed and signaling cascades activated by MT4-MMP that may underlie these malignancy processes and compare this with what is known about its role during embryonic development. Finally, MT4-MMP is a relevant biomarker of malignancy that can be used for monitoring cancer progression in patients as well as a potential target for future therapeutic drug development.

Elevated Plasma Levels of MT4-MMP and MT6-MMP; A New Observation in Patients with Thyroid Nodules

BACKGROUND

Based on the critical role of MT4-MMP and MT6-MMP in carcinogenesis, we focused on MT4-MMP and MT6-MMP circulating levels in patients with thyroid nodules.

METHODS

Plasma samples were collected from three groups, including papillary thyroid cancer (PTC; n=30), multinodular goiter (MNG; n=30), and healthy subjects (n=22). Enzyme-linked immunosorbent assay (ELISA) was used to obtain the concentration of MT4-MMP and MT6-MMP in the three groups.

RESULTS

Analysis of data demonstrated increased levels of MT4-MMP (PTC: 4.90±1.35, MNG: 4.89±1.37, and healthy: 3.13±1.42) and MT6-MMP (PTC: 8.29±2.50, MNG: 7.34±2.09, and healthy:5.01±2.13) in thyroid nodules by comparison with healthy subjects (P<0.05). There were no significant differences in the levels of the two MT-MMPs between PTC and MNG (P>0.05). Increased plasma levels of MT4-MMP (odds ratio=2.48; 95% CI: 1.46-4.19; P=0.001) or MT6-MMP (odds ratio=1.81; 95% CI: 1.29-2.53; P=0.001) were associated with increased risk of PTC tumorigenesis. Interestingly, a strong positive association was observed between MT4-MMP and MT6-MMP in the three groups (PTC: r=0.766**, P=0.000; MNG: r=0.856**, P=0.000; healthy r=0.947**, P=0.000). Areas under the ROC curve for MT4-MMP and MT6-MMP were 0.82 and 0.96, respectively. At the cutoff value>4.7 (ng/mL), MT4-MMP and MT6-MMP showed a sensitivity of 63.3% and 90.0%, respectively, with 100% specificity.

CONCLUSION

Our work has led us to imply that the higher levels of MT4-MMP and MT6-MMP are closely linked with both PTC and MNG tumorigenesis. They may probably promote the development of thyroid lesions; however, more research is needed to further clarify the current findings.

MT4-MMP promotes invadopodia formation and cell motility in FaDu head and neck cancer cells

Hypoxia-inducible factor-1α (HIF-1α) induces cancer metastasis. We previously demonstrated that HIF-1α-induced membrane-type 4 matrix metalloproteinase (MT4-MMP) is involved in hypoxia-mediated metastasis in head and neck squamous cell carcinoma (HNSCC). However, the functions and detailed mechanisms of MT4-MMP in cancer metastasis are not well understood. In this study, we investigated whether MT4-MMP regulates invadopodia formation or individual cell movement-both critical to cancer migration and invasion-in three-dimensional (3D) environments. By expressing MT4-MMP in the HNSCC cell line FaDu, we demonstrated that MT4-MMP increases invadopodia formation and gelatin degradation. Furthermore, the amoeboid-like cell movement on collagen gel was increased by MT4-MMP expression in FaDu cells. Mechanistically, MT4-MMP may induce invadopodia formation by binding with Tks5 and PDGFRα to result in Src activation and promote amoeboid-like movement by stimulating the small GTPases Rho and Cdc42. Altogether, our data indicate that MT4-MMP induces two crucial mechanisms of cancer dissemination, invadopodia formation and amoeboid movement, and elucidate the prometastatic role of MT4-MMP in hypoxia-mediated cancer metastasis.

MT4-MMP Modulates the Expression of miRNAs in Breast Cancer Cells

BACKGROUND

MT4-MMP is a member of the metalloproteinases family, although with a controversial role in the extracellular matrix remodelation. Overexpression of this metalloproteinase has been observed in breast cancer and it has been suggested that it can regulate tumor growth and cancer progression. The mechanisms by which MT4-MMP participates in breast cancer includes tumor blood vessels desestabilization, the activation of an angiogenic switch, and increase of EGFR signaling. However, all the mechanisms by which MT4-MMP participates in breast cancer are still unknowns.

AIM OF THE STUDY

To study if MT4-MMP could modulate the expression of microRNAs (miRNAs) related to biological processes associated with tumor formation and progression.

METHODS

MT4-MMP was ectopically overexpressed in MDA-MB-231 cells and the miRNAs expression profile modulated by the metalloproteinase was studied by using miRNAs microarrays. Microarray data were analyzed with different tools to find the molecular and cellular functions related to the differentially expressed miRNAs. The clinical relevance of some miRNAs was analyzed using a public database.

RESULTS

MT4-MMP overexpression in breast cancer cells induced the modulation of 65 miRNAs, which were related to the alteration of pathways dependent of p53, TGF-β, MAPK, ErbB, and Wnt, as well as processes such as cell cycle, adherens junctions, apoptosis, and focal adhesion. Several of the upregulated miRNAs were associated to a worse prognosis in breast cancer patients.

CONCLUSIONS

In breast cancer cells, the overexpression of MT4-MMP modulates the expression of miRNAs involved in several biological processes associated with tumor formation and progression and with clinical relevance.

MT4-MMP: The GPI-Anchored Membrane-Type Matrix Metalloprotease with Multiple Functions in Diseases

MT4-MMP (or MMP17) belongs to the Membrane-Type Matrix Metalloproteinase (MT-MMP) family. This family of proteases contributes to extracellular matrix remodeling during several physiological processes, including embryogenesis, organogenesis, tissue regeneration, angiogenesis, wound healing, and inflammation. MT4-MMP (MMP17) presents unique characteristics compared to other members of the family in terms of sequence homology, substrate specificity, and internalization mode, suggesting distinct physiological and pathological functions. While the physiological functions of MT4-MMP are poorly understood, it has been involved in different pathological processes such as arthritis, cardiovascular disease, and cancer progression. The mt4-mmp transcript has been detected in a large diversity of cancers. The contribution of MT4-MMP to tumor development has been further investigated in gastric cancer, colon cancer, head and neck cancer, and more deeply in breast cancer. Given its contribution to different pathologies, particularly cancers, MT4-MMP represents an interesting therapeutic target. In this review, we examine its biological and structural properties, and we propose an overview of its physiological and pathological functions.