Identification of binding partners that facilitate membrane-type 5 matrix metalloproteinase (MT5-MMP) processing of amyloid precursor protein.

One of the pathological hallmarks of Alzheimer's disease (AD) is the presence of extracellular deposits of amyloid beta (Aß) peptide. In addition to Aß as the core component of the amyloid plaque, the amyloid precursor protein (APP) processing fragment Aß was also found accumulated around the plaque. The APPη pathway, mainly mediated by membrane-type 5 matrix metalloproteinase (MT5-MMP), represents an important factor in AD pathogenesis. The proamyloidogenic features of MT5-MMP could result from interactions with APP when trafficking between organelles, so determination of the location within the cell of APPη cleavage and interacting proteins of MT5-MMP affecting this process will be of priority in understanding the role of MT5-MMP in AD. In the present study, MT5-MMP was found to be located in the nucleus, cytosol, and cytosolic subcellular granules of CHO cells that stably expressed wild-type human APP751. MT5-MMP fusion proteins were constructed that could localize enzyme production in the Golgi apparatus, endosome, ER, mitochondria, or plasma membrane. The fusion proteins significantly increased sAPPη when directed to the endosome, Golgi apparatus, plasma membrane, or mitochondria. Since the C-terminal region of MT5-MMP is responsible for its intracellular location and trafficking, this domain was used as the bait in a yeast two-hybrid screen to identify MT5-MMP protein partners in a human brain cDNA library. Identified binding partners included N4BP2L1, TMX3, EIG121, bridging Integrator 1 (BIN1), RUFY4, HTRA1, and TMEM199. The binding of N4BP2L1, EIG121, BIN1, or TMX3 to MT5-MMP resulted in the most significant increase in sAPPη production. Thus, the action of MT5-MMP on APP occurs in multiple locations within the cell and is facilitated by site-specific binding partners.

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.

The Catalytic Domain Mediates Homomultimerization of MT1-MMP and the Prodomain Interferes with MT1-MMP Oligomeric Complex Assembly.

Homomultimerization of MT1-MMP (membrane type 1 matrix metalloproteinase) through the hemopexin, transmembrane, and cytoplasmic domains plays a very important role in the activation of proMMP-2 and the degradation of pericellular collagen. MT1-MMP is overexpressed in many types of cancers, and it is considered to be a key enzyme in facilitating cancer cell migration. Since the oligomerization of MT1-MMP is important for its proteolytic activity in promoting cancer invasion, we have further investigated the multimerization by using heterologously expressed MT1-MMP ectodomains in insect cells to gain additional mechanistic insight into this process. We show that the whole ectodomain of MT1-MMP can form dimers and higher-order oligomeric complexes. The enzyme is secreted in its active form and the multimeric complex assembly is mediated by the catalytic domain. Blocking the prodomain removal determines the enzyme to adopt the monomeric structure, suggesting that the prodomain prevents the MT1-MMP oligomerization process. The binding affinity of MT1-MMP to type I collagen is dependent on the oligomeric state. Thus, the monomers have the weakest affinity, while the binding strength increases proportionally with the complexity of the multimers. Collectively, our experimental results indicate that the catalytic domain of MT1-MMP is necessary and sufficient to mediate the formation of multimeric structures.

Emerging roles of MT-MMPs in embryonic development.

Membrane-type matrix metalloproteinases (MT-MMPs) are cell membrane-tethered proteinases that belong to the family of the MMPs. Apart from their roles in degradation of the extracellular milieu, MT-MMPs are able to activate through proteolytic processing at the cell surface distinct molecules such as receptors, growth factors, cytokines, adhesion molecules, and other pericellular proteins. Although most of the information regarding these enzymes comes from cancer studies, our current knowledge about their contribution in distinct developmental processes occurring in the embryo is limited. In this review, we want to summarize the involvement of MT-MMPs in distinct processes during embryonic morphogenesis, including cell migration and proliferation, epithelial-mesenchymal transition, cell polarity and branching, axon growth and navigation, synapse formation, and angiogenesis. We also considered information about MT-MMP functions from studies assessed in pathological conditions and compared these data with those relevant for embryonic development.

MT5-MMP controls APP and ß-CTF/C99 metabolism through proteolytic-dependent and -independent mechanisms relevant for Alzheimer's disease.

We previously discovered the implication of membrane-type 5-matrix metalloproteinase (MT5-MMP) in Alzheimer's disease (AD) pathogenesis. Here, we shed new light on pathogenic mechanisms by which MT5-MMP controls the processing of amyloid precursor protein (APP) and the fate of amyloid beta peptide (Aß) as well as its precursor C99, and C83. We found in human embryonic kidney cells (HEK) carrying the APP Swedish familial mutation (HEKswe) that deleting the C-terminal non-catalytic domains of MT5-MMP hampered its ability to process APP and release the soluble 95 kDa form (sAPP95). Catalytically inactive MT5-MMP variants increased the levels of Aß and promoted APP/C99 sorting in the endolysosomal system, likely through interactions of the proteinase C-terminal portion with C99. Most interestingly, the deletion of the C-terminal domain of MT5-MMP caused a strong degradation of C99 by the proteasome and prevented Aß accumulation. These discoveries reveal new control of MT5-MMP over APP by proteolytic and non-proteolytic mechanisms driven by the C-terminal domains of the proteinase. The targeting of these non-catalytic domains of MT5-MMP could, therefore, provide new insights into the therapeutic regulation of APP-related pathology in AD.

The Role of the Metzincin Superfamily in Prostate Cancer Progression: A Systematic-Like Review.

Prostate cancer remains a leading cause of cancer-related morbidity in men. Potentially important regulators of prostate cancer progression are members of the metzincin superfamily of proteases, principally through their regulation of the extracellular matrix. It is therefore timely to review the role of the metzincin superfamily in prostate cancer and its progression to better understand their involvement in this disease. A systematic-like search strategy was conducted. Articles that investigated the roles of members of the metzincin superfamily and their key regulators in prostate cancer were included. The extracted articles were synthesized and data presented in tabular and narrative forms. Two hundred and five studies met the inclusion criteria. Of these, 138 investigated the role of the Matrix Metalloproteinase (MMP) subgroup, 34 the Membrane-Tethered Matrix Metalloproteinase (MT-MMP) subgroup, 22 the A Disintegrin and Metalloproteinase (ADAM) subgroup, 8 the A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) subgroup and 53 the Tissue Inhibitor of Metalloproteinases (TIMP) family of regulators, noting that several studies investigated multiple family members. There was clear evidence that specific members of the metzincin superfamily are involved in prostate cancer progression, which can be either in a positive or negative manner. However, further understanding of their mechanisms of action and how they may be used as prognostic indicators or molecular targets is required.

The prognostic value and potential mechanism of Matrix Metalloproteinases among Prostate Cancer.

Background: Matrix Metalloproteinases (MMPs) play an indispensable role in the initial alteration and development of PCa. We tried to generate an MMP-related prognostic signature (MMPS) in prostate cancer (PCa). Methods: TCGA-PRAD, MSKCC/GSE21032, GSE116918, GSE70769 cohorts were enrolled to assess the prognostic value of MMPs. The least absolute shrinkage and selection operator (LASSO) Cox regression was employed to generate the MMPS signature. The log-rank test and Kaplan-Meier (K-M) survival curve were applied to show the difference RFS, The receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) was plotted to predict the accuracy of signature. CIBERSORT was conducted to analyze the different immune infiltration in MMPS-H and MMPS-L groups. Potential signaling pathways activated in the MMPS-H groups by Metascape. Results: MMP1, MMP7, MMP11, MMP24 and MMP26 were selected by LASSO regression and established the MMPS predict signature. The MMPS showed the high prognostic value in TCGA-PRAD training cohort (AUC=0.714) and validation cohorts (GSE116918: AUC=0.976, GSE70769: AUC=0.738, MSKCC: AUC=0.793). Pid integrin1 pathway, G2M checkpoint, and response to growth factor signaling pathways were activated in MMPS-H group, patients with the high MMPS risk score and low M2 macrophage showed the worst recurrence-free survival (RFS). Conclusion: MMPs involved and played an essential role in the tumorigenesis and biochemical recurrence in PCa patients. The MMPS signature could accurately predict the recurrence of PCa patients and validated in several cohorts.

Role of Cyclosporine in Gingival Hyperplasia: An In Vitro Study on Gingival Fibroblasts.

BACKGROUND: Gingival hyperplasia could occur after the administration of cyclosporine A. Up to 90% of the patients submitted to immunosuppressant drugs have been reported to suffer from this side effect. The role of fibroblasts in gingival hyperplasia has been widely discussed by literature, showing contrasting results. In order to demonstrate the effect of cyclosporine A on the extracellular matrix component of fibroblasts, we investigated the gene expression profile of human fibroblasts after cyclosporine A administration. MATERIALS AND METHODS: Primary gingival fibroblasts were stimulated with 1000 ng/mL cyclosporine A solution for 16 h. Gene expression levels of 57 genes belonging to the "Extracellular Matrix and Adhesion Molecules" pathway were analyzed using real-time PCR in treated cells, compared to untreated cells used as control. RESULTS: Expression levels of different genes were significantly de-regulated. The gene CDH1, which codes for the cell adhesion protein E-cadherin, showed up-regulation. Almost all the extracellular matrix metalloproteases showed down-regulation (MMP8, MMP11, MMP15, MMP16, MMP24, MMP26). The administration of cyclosporine A was followed by down-regulation of other genes: COL7A1, the transmembrane receptors ITGB2 and ITGB4, and the basement membrane constituents LAMA2 and LAMB1. CONCLUSION: Data collected demonstrate that cyclosporine inhibits the secretion of matrix proteases, contributing to the accumulation of extracellular matrix components in the gingival connective tissue, causing gingival overgrowth. Patients affected by gingival overgrowth caused by cyclosporine A need to be further investigated in order to determine the role of this drug on fibroblasts.

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.

Melanoma cell adhesion molecule is the driving force behind the dissemination of melanoma upon S100A8/A9 binding in the original skin lesion.

Since metastasis accounts for the majority of cancer-associated deaths, studies on the mechanisms of metastasis are needed to establish innovative strategies for cancer treatment. We previously reported that melanoma cell adhesion molecule (MCAM) functions as a critical receptor for S100A8/A9, and binding of S100A8/A9 to MCAM results in the migration of melanoma cells to lung tissue. However, the critical role of MCAM in the original melanoma skin lesion is still not clear. In this study, we aimed to determine the importance of the S100A8/A9-MCAM axis in melanoma dissemination in a skin lesion as a critical early step for metastasis. Mechanistic studies revealed the downstream signaling of MCAM that signaled the induction of metastasis. S100A8/A9-MCAM binding activates mitogen-activated protein kinase kinase kinase 8 (MAP3K8), also termed TPL2, leading to strong activation of the transcription factor ETV4 and subsequent induction of matrix metalloproteinase-25 (MMP25), and finally to induction of melanoma lung tropic metastasis. Collectively, our results demonstrate a crucial role of the S100A8/A9-MCAM signaling axis in metastatic onset of melanoma cells and indicate that strategies targeting the identified pathway may be useful for the establishment of innovative anti-cancer therapies.

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.

Expression of MT4-MMP, EGFR, and RB in Triple-Negative Breast Cancer Strongly Sensitizes Tumors to Erlotinib and Palbociclib Combination Therapy.

PURPOSE: Here, we investigated the clinical relevance of an unprecedented combination of three biomarkers in triple-negative breast cancer (TNBC), both in human samples and in patient-derived xenografts of TNBC (PDX-TNBC): EGFR, its recently identified partner (MT4-MMP), and retinoblastoma protein (RB).Experimental Design: IHC analyses were conducted on human and PDX-TNBC samples to evaluate the production of the three biomarkers. The sensitivity of cancer cells expressing or not MT4-MMP to anti-EGFR (erlotinib) or anti-CDK4/6 inhibitor (palbociclib) was evaluated in vitro in 2D and 3D proliferation assays and in vivo using xenografts and PDX-TNBC displaying different RB, MT4-MMP, and EGFR status after single (erlotinib or palbociclib) or combined (erlotinib + palbociclib) treatments. RESULTS: EGFR and MT4-MMP were coexpressed in >70% of TNBC samples and PDX-TNBC, among which approximately 60% maintained RB expression. Notably, approximately 50% of all TNBC and PDX-TNBC expressed the three biomarkers. Single erlotinib and palbociclib treatments drastically reduced the in vitro proliferation of cells expressing EGFR and MT4-MMP when compared with control cells. Both TNBC xenografts and PDX expressing MT4-MMP, EGFR, and RB, but not PDX-TNBC with RB loss, were sensitive to erlotinib and palbociclib with an additive effect of combination therapy. Moreover, this combination was efficient in another PDX-TNBC expressing the three biomarkers and resistant to erlotinib alone. CONCLUSIONS: We defined a new association of three biomarkers (MT4-MMP/EGFR/RB) expressed together in 50% of TNBC and demonstrated its usefulness to predict the TNBC response to anti-EGFR and anti-CDK4/6 drugs used in single or combined therapy.

Micro-RNAs as critical regulators of matrix metalloproteinases in cancer.

Metastasis is known to be one of the important factors associated with cancer-related deaths worldwide. Several cellular and molecular targets are involved in the metastasis process. Among these targets, matrix metalloproteinases (MMPs) play central roles in promoting cancer metastasis. MMPs could contribute toward tumor growth, angiogenesis, migration, and invasion via degradation of the extracellular matrix and activation of pre-pro-growth factors. Therefore, identification of various cellular and molecular pathways that affect MMPs could contribute toward a better understanding of the metastatic pathways involved in various tumors. Micro-RNAs are important targets that could affect MMPs. Multiple lines of evidence have indicated that deregulation of various micro-RNAs, including miR-9, Let-7, miR-10b, and miR-15b, affects metastasis of tumor cells via targeting MMPs.

Extracellular gamma-synuclein promotes tumor cell motility by activating ß1 integrin-focal adhesion kinase signaling pathway and increasing matrix metalloproteinase-24, -2 protein secretion.

BACKGROUND: Increasing evidence reveals a significant correlation between gamma-synuclein (SNCG) level and tumor invasion and metastasis in various human cancers. Our previous investigation showed that SNCG could secrete into extracellular environment and promoted tumor cell motility, but the mechanism is unknown. METHODS: The membrane binding ability of SNCG was characterized by immunohistochemical staining, immunofluorescence staining and fractionation of colorectal cancer (CRC) cell membrane. Association between SNCG and ß1 integrin was validated by coimmunoprecipitation and far Western blot. After inhibition of ß1 integrin and focal adhesion kinase (FAK), effect of SNCG on cell motility was measured by transwell chamber assays and changes of protein levels were detected by Western blot. Association between SNCG and activated ß1 integrin levels in human CRC tissues was determined by Spearman's rank correlation analysis. Secreted proteins in conditioned medium (CM) were screened by antibody array. RESULTS: Extracellular SNCG bound ß1 integrin on CRC cell membrane and increased levels of activated ß1 integrin and FAK. Correspondingly, SNCG-enhanced cell motility was counteracted by knockdown or inhibition of ß1 integrin or FAK. Further study revealed that high SNCG level indicated poor outcome and SNCG levels positively correlated with those of activated ß1 integrin and phospho-FAK (Tyr397) in human CRC tissues. Additionally, extracellular SNCG promoted secretion of fibronectin (FN), vitronectin (VN), matrix metalloproteinase (MMP)-2, and MMP-24 from HCT116 cells. Protease activity of MMP-2 in the CM of HCT116 cells was increased by treatment with SNCG, which was abolished by inhibiting ß1 integrin. CONCLUSION: Our results highlight the potential role of SNCG in remodeling extracellular microenvironment and inducing ß1 integrin-FAK signal pathway of CRC cells.

Biological function evaluation and effects of laser micro-pore burn-denatured acellular dermal matrix.

OBJECTIVE: In the field of burns repairs, many problems exist in the shortage of donor skin, the expense of allograft or xenograft skin, temporary substitution and unsatisfactory extremity function after wound healing. Previous studies showed that burn-denatured skin could return to normal dermis formation and function. This study investigates the application of laser micro-pore burn-denatured acellular dermis matrix (DADM) from an escharotomy in the repair of burn wounds and evaluates the biological properties and wound repair effects of DADM in implantation experiments in Kunming mice. METHODS: Specific-pathogen-free (SPF) Kunming mice were used in this study. A deep II° burn wound was created on the dorsum of the mice by an electric heated water bath. The full-thickness wound tissue was harvested. The necrotic tissue and subcutaneous tissue were removed. The denatured dermis was preserved and treated with 0.25% trypsin, 0.5% Triton X-100. The DADM was drilled by laser micro-pore. The biological properties and grafting effects of laser micro-pore burn-DADM were evaluated by morphology, cytokine expression levels and subcutaneous implantation experiments in Kunming mice. RESULTS: We found statistical significance (P<0.05) of the elastic modulus (MPa), maximum load force (N) and contraction measurement (CM) of the laser micro-pore burn-DADM (experimental group) compared to the control group (no laser micro-pore burn-DADM). Cytokine expression level was different in the dermal matrixes harvested at various time points after burn (24h, 48h, 72h and infected wound group). Comparing the dermal matrix from 24h burn tissue to infected wound tissue, the expression level of IL-6, MMP-24, VE-cadherin and VEGF were decreased. We found no inflammatory cells infiltration in the dermal matrix were observed in both experimental and control groups (24h burn group), while the obviously vascular infiltration and fiber fusion were observed in the experimental group after subcutaneous implantation experiments. CONCLUSION: There was better bio-performance, low immunogenicity and better dermal incorporation after treated by laser micro-pore drilling and decellularized deep II° burn-DADM, which may be considered as a better substitute for dermal matrix. Furthermore, the earlier harvested DADM after burn (24h) shows the better transplantation effect.

Gaseous signalling molecule SO2 via Hippo­MST pathway to improve myocardial fibrosis of diabetic rats.

Recent studies have indicated the existence of an endogenous sulfur dioxide (SO2)­generating system in the cardiovascular system. The present study aimed to discuss the function and regulatory mechanism of gaseous signal molecule SO2 in inhibiting apoptosis and endoplasmic reticulum stress (ERS) via the Hippo­MST signaling pathway to improve myocardial fibrosis of diabetic rats. A total of 40 male Sprague­Dawley rats were randomly divided into four groups (10 rats per group): Normal control group (control group), diabetic rats group [streptozotocin (STZ) group], SO2 intervention group (STZ+SO2 group) and diabetes mellitus rats treated with L­Aspartic acid ß­hydroxamate (HDX) group (HDX group). Diabetic rats models were established by intra­peritoneal injection of STZ (40 mg/kg) Following model establishment, intra­peritoneal injection of Na2SO3/NaHSO3 solution (0.54 mmol/kg) was administered in the STZ+SO2 group, and HDX solution (25 mg/kg/week) was administered in the HDX group. A total of 4 weeks later, echocardiography was performed to evaluate rats' cardiac function; Masson staining, terminal deoxynucleotidyl transferase dUTP nick end labeling staining and transmission electron microscopy examinations were performed to observe myocardial morphological changes. ELISA was employed to determine the SO2 content. Western blot analysis was performed to detect the expression of proteins associated with apoptosis, ERS and the Hippo­MST signalling pathway. Compared with the control group, the STZ group and HDX group had a disordered arrangement of myocardial cells with apparent myocardial fibrosis, and echocardiography indicated that the cardiac function was lowered, there was an obvious increase of apoptosis in myocardial tissue, the expression levels of apoptosis­associated protein B­cell lymphoma associated protein X, caspase­3 and caspase­9 were upregulated, and Bcl­2 expression was downregulated. The expression of ERS and Hippo­MST pathway­associated proteins, including CHOP, GRP94, MST1 and MST2, were significantly upregulated. By contrast, these above­mentioned changes were reversed by SO2 treatment. Compared with STZ group, the HDX group had a further increase of myocardial fibrosis and apoptosis, while there were no statistically significant differences in the expression of Bax/Bcl­2, caspase­3, caspase­9 and ERS and Hippo­MST pathway­associated proteins. The results of the present study demonstrated that the gaseous signal molecule SO2 can effectively improve the myocardial fibrosis of diabetic rats, and its mechanism may be associated with reduced apoptosis and ERS by downregulated Hippo­MST pathway.

Expression and Characterization of Membrane-Type 4 Matrix Metalloproteinase (MT4-MMP) and its Different Forms in Melanoma.

BACKGROUND/AIMS: Membrane-type matrix metalloproteinases (MT-MMPs) are expressed on the cell surface and hydrolyze extracellular matrix components and signaling molecules by which they influence cancer cell migration and metastasis. Two of the six known MT-MMPs are anchored to the plasma membrane via a GPI anchor, one of which is MT4-MMP. Only little is known about MT4-MMP expression, synthesis, regulation and degradation. METHODS: We analyzed several human cancer cell lines as well as tissue homogenates using Western blotting and quantitative PCR for the expression of MT4-MMP. Organelles of SK-Mel-28 cells were separated using continuous Iodixanol gradients. Glycosylation of the SK-Mel-28 protein was studied via glucosidases and site directed mutagenesis of the MT4-MMP cDNA prior to transfection. RESULTS: We found the MT4-MMP highly expressed in human melanoma cell lines as well as skin and melanoma tissue samples. Three forms of MT4-MMP with molecular masses of 45 kDa, 58 kDa and 69 kDa were detected. Further, we demonstrate that the 58 kDa form is the mature protein in the cell membrane, while the 69 kDa form is its precursor found in intracellular compartments. The 69 kDa forms are processed by furin cleavage in the Golgi apparatus. Moreover, we identified Asn318 as the single N-glycosylation site of MT4-MMP. CONCLUSION: We demonstrate the novel expression of MT4-MMP in melanocytic tissues and propose a precursor/product-relationship of the different forms of MT4-MMP in melanoma cells.

MT4-MMP and EGFR expression levels are key biomarkers for breast cancer patient response to chemotherapy and erlotinib.

BACKGROUND: Triple-negative breast cancers (TNBC) are heterogeneous cancers with poor prognosis. We aimed to determine the clinical relevance of membrane type-4 matrix metalloproteinase (MT4-MMP), a membrane type matrix metalloproteinase that interacts with epidermal growth factor receptor (EGFR) overexpressed in >50% of TNBC. METHODS: We conducted a retrospective immunohistochemical analysis on human TNBC samples (n=81) and validated our findings in in vitro and in vivo assays. RESULTS: Membrane type-4 matrix metalloproteinase and EGFR are produced in 72.5% of TNBC samples, whereas those proteins are faintly produced by healthy tissues. Unexpectedly, tumour relapse after chemotherapy was reduced in samples highly positive for MT4-MMP. Mechanistically, this is ascribed to a higher sensitivity of MT4-MMP-producing cells to alkylating or intercalating chemotherapeutic agents, as assessed in vitro. In sharp contrast, MT4-MMP expression did not affect tumour cell sensitivity to paclitaxel that interferes with protease trafficking. Importantly, MT4-MMP expression sensitised cancer cells to erlotinib, a tyrosine kinase EGFR inhibitor. In a pre-clinical model, the growth of MT4-MMP overexpressing xenografts, but not of control ones, was reduced by epirubicin or erlotinib. The combination of suboptimal drug doses blocked drastically the growth of MT4-MMP-producing tumours. CONCLUSIONS: We demonstrate that MT4-MMP defines a sub-population of TNBC sensitive to a combination of DNA-targeting chemotherapeutic agents and anti-EGFR drugs.

Identifying key stage-specific genes and transcription factors for gastric cancer based on RNA-sequencing data.

BACKGROUND: To identify gastric cancer (GC)-associated genes and transcription factors (TFs) using RNA-sequencing (RNA-seq) data of Asians. MATERIALS AND METHODS: The RNA-seq data (GSE36968) were downloaded from Gene Expression Omnibus database, including 6 noncancerous gastric tissue samples, 5 stage I GC samples, 5 stage II GC samples, 8 stage III GC samples, and 6 stage IV GC samples. The gene expression values in each sample were calculated using Cuffdiff. Following, stage-specific genes were identified by 1-way analysis of variance and hierarchical clustering analysis. Upstream TFs were identified using Seqpos. Besides, functional enrichment analysis of stage-specific genes was performed by DAVID. In addition, the underlying protein-protein interactions (PPIs) information among stage IV-specific genes were extracted from STRING database and PPI network was constructed using Cytoscape software. RESULTS: A total of 3576 stage-specific genes were identified, including 813 specifically up-regulated genes in the normal gastric tissues, 2224 stage I and II-specific genes, and 539 stage IV-specific genes. Also, a total of 9 and 11 up-regulated TFs were identified for the stage I and II-specific genes and stage IV-specific genes, respectively. Functional enrichment showed SPARC, MMP17, and COL6A3 were related to extracellular matrix. Notably, 2 regulatory pathways HOXA4-GLI3-RUNX2-FGF2 and HMGA2-PRKCA were obtained from the PPI network for stage IV-specific genes. In the PPI network, TFs HOXA4 and HMGA2 might function via mediating other genes. CONCLUSION: These stage-specific genes and TFs might act in the pathogenesis of GC in Asians.

Inactivation of Capicua drives cancer metastasis.

Metastasis is the leading cause of death in people with lung cancer, yet the molecular effectors underlying tumor dissemination remain poorly defined. Through the development of an in vivo spontaneous lung cancer metastasis model, we show that the developmentally regulated transcriptional repressor Capicua (CIC) suppresses invasion and metastasis. Inactivation of CIC relieves repression of its effector ETV4, driving ETV4-mediated upregulation of MMP24, which is necessary and sufficient for metastasis. Loss of CIC, or an increase in levels of its effectors ETV4 and MMP24, is a biomarker of tumor progression and worse outcomes in people with lung and/or gastric cancer. Our findings reveal CIC as a conserved metastasis suppressor, highlighting new anti-metastatic strategies that could potentially improve patient outcomes.