ADAM12 is selectively overexpressed in human glioblastomas and is associated with glioblastoma cell proliferation and shedding of heparin-binding epidermal growth factor

ADAM12-Generated Basigin Ectodomain Binds β1 Integrin and Enhances the Expression of Cancer-Related Extracellular Matrix Proteins

Desmoplasia is a common feature of aggressive cancers, driven by a complex interplay of protein production and degradation. Basigin is a type 1 integral membrane receptor secreted in exosomes or released by ectodomain shedding from the cell surface. Given that soluble basigin is increased in the circulation of patients with a poor cancer prognosis, we explored the putative role of the ADAM12-generated basigin ectodomain in cancer progression. We show that recombinant basigin ectodomain binds β1 integrin and stimulates gelatin degradation and the migration of cancer cells in a matrix metalloproteinase (MMP)- and β1-integrin-dependent manner. Subsequent in vitro and in vivo experiments demonstrated the altered expression of extracellular matrix proteins, including fibronectin and collagen type 5. Thus, we found increased deposits of collagen type 5 in the stroma of nude mice tumors of the human tumor cell line MCF7 expressing ADAM12-mimicking the desmoplastic response seen in human cancer. Our findings indicate a feedback loop between ADAM12 expression, basigin shedding, TGFβ signaling, and extracellular matrix (ECM) remodeling, which could be a mechanism by which ADAM12-generated basigin ectodomain contributes to the regulation of desmoplasia, a key feature in human cancer progression.

Abnormal glycosylation in glioma: related changes in biology, biomarkers and targeted therapy

Glioma is a rapidly growing and aggressive primary malignant tumor of the central nervous system that can diffusely invade the brain tissue around, and the prognosis of patients is not significantly improved by traditional treatments. One of the most general posttranslational modifications of proteins is glycosylation, and the abnormal distribution of this modification in gliomas may shed light on how it affects biological behaviors of glioma cells, including proliferation, migration, and invasion, which may be produced by regulating protein function, cell-matrix and cell‒cell interactions, and affecting receptor downstream pathways. In this paper, from the perspective of regulating protein glycosylation changes and abnormal expression of glycosylation-related proteins (such as glycosyltransferases in gliomas), we summarize how glycosylation may play a crucial role in the discovery of novel biomarkers and new targeted treatment options for gliomas. Overall, the mechanistic basis of abnormal glycosylation affecting glioma progression remains to be more widely and deeply explored, which not only helps to inspire researchers to further explore related diagnostic and prognostic markers but also provides ideas for discovering effective treatment strategies and improving glioma patient survival and prognosis.

ADAM12 promotes clear cell renal cell carcinoma progression and triggers EMT via EGFR/ERK signaling pathway

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is a major worldwide health problem due to its high prevalence and mortality rate. A disintegrin and metalloproteinase 12 (ADAM12) is aberrantly expressed in various cancers and plays an important role in tumor progression. However, its explicit effect and molecular mechanism in ccRCC remain unclear.

METHODS

We investigated the dysregulation of ADAM12 in ccRCC through public databases and bioinformatics analyses. The expression of ADAM12 was further verified in ccRCC tissues by RT-qPCR and immunohistochemistry (IHC). The relationship between ADAM12 expression and clinicopathological characteristics was analyzed statistically. The effects of ADAM12 on the proliferation, migration and invasion of ccRCC cells were examined by in vitro and in vivo experiments.

RESULTS

ADAM12 was significantly upregulated in ccRCC tissues and associated with poor prognosis in ccRCC patients. ADAM12 promoted ccRCC cell proliferation, migration and invasion in vitro and the growth of subcutaneous tumors in vivo. Knockdown of ADAM12 successfully suppressed its oncogenic function. Mechanistically, its overexpression induced epithelial-mesenchymal transition (EMT) by downregulating E-cadherin and upregulating N-cadherin and Snail. Moreover, ADAM12 participated in the epidermal growth factor receptor (EGFR) pathway and activated the downstream signal ERK1/2 by shedding the EGFR ligand, thereby upregulating target genes including c-Myc, enhancing cell survival and invasion ability, and promoting tumor progression, metastasis and the induction of EMT.

CONCLUSIONS

High expression of ADAM12 induced EMT and promoted cell proliferation, migration, and invasion by activating the EGFR/ERK signaling pathway in ccRCC.

The Biochemistry and Physiology of A Disintegrin and Metalloproteinases (ADAMs and ADAM-TSs) in Human Pathologies

Metalloproteinases are a group of proteinases that plays a substantial role in extracellular matrix remodeling and its molecular signaling. Among these metalloproteinases, ADAMs (a disintegrin and metalloproteinases) and ADAM-TSs (ADAMs with thrombospondin domains) have emerged as highly efficient contributors mediating proteolytic processing of various signaling molecules. ADAMs are transmembrane metalloenzymes that facilitate the extracellular domain shedding of membrane-anchored proteins, cytokines, growth factors, ligands, and their receptors and therefore modulate their biological functions. ADAM-TSs are secretory, and soluble extracellular proteinases that mediate the cleavage of non-fibrillar extracellular matrix proteins. ADAMs and ADAM-TSs possess pro-domain, metalloproteinase, disintegrin, and cysteine-rich domains in common, but ADAM-TSs have characteristic thrombospondin motifs instead of the transmembrane domain. Most ADAMs and ADAM-TSs are activated by cleavage of pro-domain via pro-protein convertases at their N-terminus, hence directing them to various signaling pathways. In this article, we are discussing not only the structure and regulation of ADAMs and ADAM-TSs, but also the importance of these metalloproteinases in various human pathophysiological conditions like cardiovascular diseases, colorectal cancer, autoinflammatory diseases (sepsis/rheumatoid arthritis), Alzheimer's disease, proliferative retinopathies, and infectious diseases. Therefore, based on the emerging role of ADAMs and ADAM-TSs in various human pathologies, as summarized in this review, these metalloproteases can be considered as critical therapeutic targets and diagnostic biomarkers.

MicroRNA-149 Regulates Proliferation, Migration, and Invasion of Pituitary Adenoma Cells by Targeting ADAM12 and MMP14

OBJECTIVE

Pituitary adenomas (PAs) can adapt an aggressive phenotype by invading adjacent brain structures with rapid cellular proliferation. Previous studies demonstrated that excessive expression of metalloproteases ADAM12 and MMP-14 is instrumental for the active proliferation and invasiveness of PA cells in vitro and of tumors in vivo. However, the mechanisms regulating ADAM12 and MMP-14 expression in PAs remain unclear.

METHODS

Target gene prediction and transcriptomic profiling of invasive vs. noninvasive human PA samples were performed to identify miRNA species potentially involved in the regulation of ADAM12 and MMP14. For cellular analyses of miRNA functions, two mouse PA cell lines (AtT20 and TtT/GF) were transfected with miR-149-3p and miR-149-5p, respectively. The effects of miR-149 (3p and 5p) on expression levels of ADAM12 and MMP14 were determined by Western blotting followed by an analysis of proliferation and colony formation assays, scratch migration assays, and invasion assays.

RESULTS

A significant downregulation of miRNA-149 was observed in invasive vs. noninvasive PA (0.32 vs. 0.09, P<0.0001). In AtT-20 and TtT/GF mouse PAs cells, transfection of mimic miRNA-149 (3p and 5p) caused a significantly reduced cell proliferation and matrigel invasion, whilst the effect on cell migration was less pronounced. Both strands of miRNA-149 (3p and 5p) markedly reduced protein levels of ADAM12 and MMP-14 by at least 40% in both cell lines.

CONCLUSION

This study proved that the invasiveness of PA cells is, at least partly, regulated by miRNA-149-dependent expression of ADAM12 and MMP-14.

Tumor Microenvironment in Glioma Invasion

A major malignant trait of gliomas is their remarkable infiltration capacity. When glioma develops, the tumor cells have already reached the distant part. Therefore, complete removal of the glioma is impossible. Recently, research on the involvement of the tumor microenvironment in glioma invasion has advanced. Local hypoxia triggers cell migration as an environmental factor. The transcription factor hypoxia-inducible factor (HIF) -1α, produced in tumor cells under hypoxia, promotes the transcription of various invasion related molecules. The extracellular matrix surrounding tumors is degraded by proteases secreted by tumor cells and simultaneously replaced by an extracellular matrix that promotes infiltration. Astrocytes and microglia become tumor-associated astrocytes and glioma-associated macrophages/microglia, respectively, in relation to tumor cells. These cells also promote glioma invasion. Interactions between glioma cells actively promote infiltration of each other. Surgery, chemotherapy, and radiation therapy transform the microenvironment, allowing glioma cells to invade. These findings indicate that the tumor microenvironment may be a target for glioma invasion. On the other hand, because the living body actively promotes tumor infiltration in response to the tumor, it is necessary to reconsider whether the invasion itself is friend or foe to the brain.

Serum-based measurements of stromal activation through ADAM12 associate with poor prognosis in colorectal cancer

Background

Recently it has been recognized that stromal markers could be used as a clinically relevant biomarker for therapy response and prognosis. Here, we report on a serum marker for stromal activation, A Disintegrin and Metalloprotease 12 (ADAM12) in colorectal cancer (CRC).

Methods

Using gene expression databases we investigated ADAM12 expression in CRC and delineated the source of ADAM12 expression. The clinical value of ADAM12 was retrospectively assessed in the CAIRO2 trial in metastatic CRC with 235 patients (31% of total cohort), and an independent rectal cancer cohort (n = 20).

Results

ADAM12 is expressed by activated CRC associated fibroblasts. In the CAIRO2 trial cohort, ADAM12 serum levels were prognostic (ADAM12 low versus ADAM12 high; median OS 25.3 vs. 17.1 months, HR 1.48 [95% CI 1.11–1.96], P = 0.007). The prognostic potential was specifically high for metastatic rectal cancer (HR 1.78 [95% CI 1.06–3.00], P = 0.030) and mesenchymal subtype tumors (HR 2.12 [95% CI 1.25–3.60], P = 0.004). ADAM12 also showed potential for predicting recurrence in an exploratory analysis of non-metastatic rectal cancers.

Conclusions

Here we describe a non-invasive marker for activated stroma in CRC which associates with poor outcome, especially for primary cancers located in the rectum.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09436-0.

A Disintegrin and Metalloproteinase (ADAM) Family: Their Significance in Malignant Tumors of the Central Nervous System (CNS)

Despite the considerable advances in diagnostic methods in medicine, central nervous system (CNS) tumors, particularly the most common ones-gliomas-remain incurable, with similar incidence rates and mortality. A growing body of literature has revealed that degradation of the extracellular matrix by matrix metalloproteinases (MMPs) might be involved in the pathogenesis of CNS tumors. However, the subfamily of MMPs, known as disintegrin and metalloproteinase (ADAM) proteins are unique due to both adhesive and proteolytic activities. The objective of our review is to present the role of ADAMs in CNS tumors, particularly their involvement in the development of malignant gliomas. Moreover, we focus on the diagnostic and prognostic significance of selected ADAMs in patients with these neoplasms. It has been proven that ADAM12, ADAMTS4 and 5 are implicated in the proliferation and invasion of glioma cells. In addition, ADAM8 and ADAM19 are correlated with the invasive activity of glioma cells and unfavorable survival, while ADAM9, -10 and -17 are associated with tumor grade and histological type of gliomas and can be used as prognostic factors. In conclusion, several ADAMs might serve as potential diagnostic and prognostic biomarkers as well as therapeutic targets for malignant CNS tumors. However, future research on ADAMs biology should be performed to elucidate new strategies for tumor diagnosis and treatment of patients with these malignancies.

Pparγ1 Facilitates ErbB2-Mammary Adenocarcinoma in Mice

HER2, which is associated with clinically aggressive disease, is overexpressed in 15-20% of breast cancers (BC). The host immune system participates in the therapeutic response of HER2⁺ breast cancer. Identifying genetic programs that participate in ErbB2-induced tumors may provide the rational basis for co-extinction therapeutic approaches. Peroxisome proliferator-activated receptor γ (PPARγ), which is expressed in a variety of malignancies, governs biological functions through transcriptional programs. Herein, genetic deletion of endogenous Pparγ1 restrained mammary tumor progression, lipogenesis, and induced local mammary tumor macrophage infiltration, without affecting other tissue hematopoietic stem cell pools. Endogenous Pparγ1 induced expression of both an EphA2-Amphiregulin and an inflammatory INFγ and Cxcl5 signaling module, that was recapitulated in human breast cancer. Pparγ1 bound directly to growth promoting and proinflammatory target genes in the context of chromatin. We conclude Pparγ1 promotes ErbB2-induced tumor growth and inflammation and represents a relevant target for therapeutic coextinction. Herein, endogenous Pparγ1 promoted ErbB2-mediated mammary tumor onset and progression. PPARγ1 increased expression of an EGF-EphA2 receptor tyrosine kinase module and a cytokine/chemokine 1 transcriptional module. The induction of a pro-tumorigenic inflammatory state by Pparγ1 may provide the rationale for complementary coextinction programs in ErbB2 tumors.

A Disintegrin and Metalloprotease 12 Promotes Tumor Progression by Inhibiting Apoptosis in Human Colorectal Cancer

Simple Summary

A disintegrin and metalloprotease 12 (ADAM12) has been associated with tumor development and progression. The aim of the current study was to evaluate the impact of ADAM12 on cancer progression, prognosis, and therapeutic targets in colorectal cancer (CRC). Our results show that ADAM12 overexpression enhanced proliferation, inhibited apoptosis, and acted as a positive regulator of cell cycle progression in CRC cells. Phosphorylation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was decreased and that of Akt was increased by ADAM12 overexpression. These results were reversed upon ADAM12 knockdown. ADAM12 overexpression was significantly associated with the cancer stage, depth of invasion, lymph node metastasis, distant metastasis, and poor survival in CRC patients. In a mouse xenograft model, tumor area, volume, and weight were significantly greater for the ADAM12 overexpression group and significantly lower for the ADAM12 knockdown group. In conclusion, ADAM12 may serve as a promising biomarker and/or therapeutic target in CRC.

Abstract

A disintegrin and metalloprotease 12 (ADAM12) has been implicated in cell growth, tumor formation, and metastasis. Therefore, we evaluated the role of ADAM12 in colorectal cancer (CRC) progression and prognosis, and elucidated whether targeted downregulation of ADAM12 could lead to therapeutic sensitization. The effect of ADAM12 on tumor cell behavior was assessed in CRC cell lines, CRC tissues, and a mouse xenograft model. ADAM12 overexpression enhanced proliferation, inhibited apoptosis, and acted as positive regulator of cell cycle progression in CRC cells. Phosphorylation of PTEN was decreased and that of Akt was increased by ADAM12 overexpression. These results were reversed upon ADAM12 knockdown. ADAM12 overexpression was significantly associated with the cancer stage, depth of invasion, lymph node metastasis, distant metastasis, and poor survival in CRC patients. In a mouse xenograft model, tumor area, volume, and weight were significantly greater for the ADAM12-pcDNA6-myc-transfected group than for the empty-pcDNA6-myc-transfected group, and significantly lower for the ADAM12-pGFP-C-shLenti-transfected group than for the scrambled pGFP-C-shLenti-transfected group. In conclusion, ADAM12 overexpression is essential for the growth and progression of CRC. Furthermore, ADAM12 knockdown reveals potent anti-tumor activity in a mouse xenograft model. Thus, ADAM12 may serve as a promising biomarker and/or therapeutic target in CRC.

Analysis of ADAM12-Mediated Ephrin-A1 Cleavage and Its Biological Functions

Accumulating evidence indicates that an elevated ephrin-A1 expression is positively correlated with a worse prognosis in some cancers such as colon and liver cancer. The detailed mechanism of an elevated ephrin-A1 expression in a worse prognosis still remains to be fully elucidated. We previously reported that ADAM12-cleaved ephrin-A1 enhanced lung vascular permeability and thereby induced lung metastasis. However, it is still unclear whether or not cleaved forms of ephrin-A1 are derived from primary tumors and have biological activities. We identified the ADAM12-mediated cleavage site of ephrin-A1 by a Matrix-assisted laser desorption ionization mass spectrometry and checked levels of ephrin-A1 in the serum and the urine derived from the primary tumors by using a mouse model. We found elevated levels of tumor-derived ephrin-A1 in the serum and the urine in the tumor-bearing mice. Moreover, inhibition of ADAM-mediated cleavage of ephrin-A1 or antagonization of the EphA receptors resulted in a significant reduction of lung metastasis. The results suggest that tumor-derived ephrin-A1 is not only a potential biomarker to predict lung metastasis from the primary tumor highly expressing ephrin-A1 but also a therapeutic target of lung metastasis.

Extracellular proteolysis in glioblastoma progression and therapeutics

Gliomas encompass highly invasive primary central nervous system (CNS) tumours of glial cell origin with an often-poor clinical prognosis. Of all gliomas, glioblastoma is the most aggressive form of primary brain cancer. Current treatments in glioblastoma are insufficient due to the invasive nature of brain tumour cells, which typically results in local tumour recurrence following treatment. The latter represents the most important cause of mortality in glioblastoma and underscores the necessity for an in-depth understanding of the underlying mechanisms. Interestingly, increased synthesis and secretion of several proteolytic enzymes within the tumour microenvironment, such as matrix metalloproteinases, lysosomal proteases, cathepsins and kallikreins for extracellular-matrix component degradation may play a major role in the aforementioned glioblastoma invasion mechanisms. These proteolytic networks are key players in establishing and maintaining a tumour microenvironment that promotes tumour cell survival, proliferation, and migration. Indeed, the targeted inhibition of these proteolytic enzymes has been a promisingly useful therapeutic strategy for glioblastoma management in both preclinical and clinical development. We hereby summarize current advances on the biology of the glioblastoma tumour microenvironment, with a particular emphasis on the role of proteolytic enzyme families in glioblastoma invasion and progression, as well as on their subsequent prognostic value as biomarkers and their therapeutic targeting in the era of precision medicine.

From putative brain tumor marker to high cognitive abilities: Emerging roles of a disintegrin and metalloprotease (ADAM) 12 in the brain

ADAM (a disintergin and metalloprotease) 12 is a member of the large family of multidomain metalloprotease-disintegrins, which possess cell-binding and metalloprotease properties. The enzyme is responsible for the shedding of a number of membrane-bound proteins (heparin-binding-EGF, insulin-like growth factor 2-binding proteins 3 and 5, oxytocinase, glycoprotein non-metastatic melanoma protein B and basigin). In rat and human CNS, ADAM12 is predominantly localized in white and gray matter oligodendrocytes. In addition it can be detected in astrocytes, neurons and endothelial cells. Its function in healthy brain is not well established yet, but prominent roles in CNS development, myelination and high cognitive abilities are discussed. There is increasing evidence that ADAM12 is involved in numerous major diseases of the CNS, which are summarized in the present review (brain tumors, multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer´s disease, stroke, schizophrenia, autism and bipolar disorder).

Role of RNA modifications in cancer

Specific chemical modifications of biological molecules are an efficient way of regulating molecular function, and a plethora of downstream signalling pathways are influenced by the modification of DNA and proteins. Many of the enzymes responsible for regulating protein and DNA modifications are targets of current cancer therapies. RNA epitranscriptomics, the study of RNA modifications, is the new frontier of this arena. Despite being known since the 1970s, eukaryotic RNA modifications were mostly identified on transfer RNA and ribosomal RNA until the last decade, when they have been identified and characterized on mRNA and various non-coding RNAs. Increasing evidence suggests that RNA modification pathways are also misregulated in human cancers and may be ideal targets of cancer therapy. In this Review we highlight the RNA epitranscriptomic pathways implicated in cancer, describing their biological functions and their connections to the disease.

SP1-Mediated Upregulation of lncRNA LINC01614 Functions a ceRNA for miR-383 to Facilitate Glioma Progression Through Regulation of ADAM12

Background

Long non-coding RNAs (lncRNAs) play an imperative role in tumorigenesis, but few lncRNAs have been functionally characterized in glioma. The aim of the present study was to identify the role of long non-coding RNA LINC01614 (LINC01614) in glioma development and explore the underlying mechanisms of LINC01614/miR-383/ADAM12 axis.

Patients and Methods

LncRNA expression in glioma specimens was measured by lncRNA microarray and qRT-PCR. The prognostic value of LINC01614 expression was statistically analyzed in 112 glioma patients. Loss-of-function experiments were conducted to investigate the biological functions of LINC01614 in vitro. Luciferase analyses, ChIP assays, and RNA pull-down were performed to determine the underlying LINC01614 mechanisms.

Results

We identified a novel glioma-related lncRNA LINC01614 by analyzing TCGA datasets. The distinct upregulation of LINC01614 was observed in both glioma specimens and cell lines using RT-PCR. We also observed that LINC01614 upregulation was induced by nuclear transcription factor SP1. Clinical assays revealed that high levels of LINC01614 were associated with KPS, WHO grade and shorter overall survival of glioma patients. Multivariate analysis further confirmed that LINC01614 was an independent prognostic marker for glioma patients. Besides, functional assays displayed that silence of LINC01614 knockdown distinctly inhibited cell growth, migration and invasion and promoted cell apoptosis in glioma cells. LINC01614 expression was enriched in the cytoplasm of glioma cells. Mechanistic investigation revealed that LINC01614 functioned as a competing endogenous RNA to upregulate a disintegrin and metalloproteinase 12 (ADAM12) by sponging miR-383.

Conclusion

Overall, these findings showed that SP1-induced upregulation of LINC01614 promoted glioma malignant progression via modulating the miR-383/ADAM12 axis, which may provide a promising therapy for glioma.

RNA modifications in brain tumorigenesis

RNA modifications are emerging as critical regulators in cancer biology, thanks to their ability to influence gene expression and the predominant protein isoforms expressed during cell proliferation, migration, and other pro-oncogenic properties. The reversibility and dynamic nature of post-transcriptional RNA modifications allow cells to quickly adapt to microenvironmental changes. Recent literature has revealed that the deregulation of RNA modifications can promote a plethora of developmental diseases, including tumorigenesis. In this review, we will focus on four key post-transcriptional RNA modifications which have been identified as contributors to the pathogenesis of brain tumors: m6A, alternative polyadenylation, alternative splicing and adenosine to inosine modifications. In addition to the role of RNA modifications in brain tumor progression, we will also discuss potential opportunities to target these processes to improve the dismal prognosis for brain tumors.

ADAM12 silencing promotes cellular apoptosis by activating autophagy in choriocarcinoma cells

ADAM metallopeptidase domain 12 (ADAM12) has been demonstrated to mediate cell proliferation and apoptosis resistance in several types of cancer cells. However, the effect of ADAM12 silencing on the proliferation and apoptosis of choriocarcinoma cells remains unknown. The present study revealed that ADAM12 silencing significantly inhibited cellular activity and proliferation in the human choriocarcinoma JEG3 cell line and increased the rate of apoptosis. In addition, ADAM12 silencing significantly increased the expression levels of the autophagy proteins microtubule-associated protein-light-chain 3 (LC3B) and autophagy related 5 (ATG5) and the fluorescence density of LC3B in JEG-3 cells. However, the suppression of autophagy by 3-methyladenine could block ADAM12 silencing-induced cellular apoptosis. ADAM12 silencing reduced the levels of the inflammatory factors interleukin-1β, interferon-γ and TNF-α, and inactivated nuclear p65-NF-κB and p-mTOR in JEG-3 cells. The downregulation of p-mTOR expression by ADAM12 silencing was rescued in 3-methyladenine-treated JEG-3 cells, indicating that mTOR might participate in the autophagy-mediated pro-apoptotic effect of ADAM12 silencing. In conclusion, ADAM12 silencing promoted cellular apoptosis in human choriocarcinoma JEG3 cells, which might be associated with autophagy and the mTOR response. These findings indicate that ADAM12 silencing might be a potential novel therapeutic target for choriocarcinoma.

Differential roles of protease isoforms in the tumor microenvironment

Alternative splicing of precursor mRNA is a key mediator of gene expression regulation leading to greater diversity of the proteome in complex organisms. Systematic sequencing of the human genome and transcriptome has led to our understanding of how alternative splicing of critical genes leads to multiple pathological conditions such as cancer. For many years, proteases were known only for their roles as proteolytic enzymes, acting to regulate/process proteins associated with diverse cellular functions. However, the differential expression and altered function of various protease isoforms, such as (i) anti-apoptotic activities, (ii) mediating intercellular adhesion, and (iii) modifying the extracellular matrix, are evidence of their specific contribution towards shaping the tumor microenvironment. Revealing the alternative splicing of protease genes and characterization of their protein products/isoforms with distinct and opposing functions creates a platform to understand how protease isoforms contribute to specific cancer hallmarks. Here, in this review, we address cancer-specific isoforms produced by the alternative splicing of proteases and their distinctive roles in the tumor microenvironment.

ADAR2/miR-589-3p axis controls glioblastoma cell migration/invasion

Recent studies have reported the emerging role of microRNAs (miRNAs) in human cancers. We systematically characterized miRNA expression and editing in the human brain, which displays the highest number of A-to-I RNA editing sites among human tissues, and in de novo glioblastoma brain cancer. We identified 299 miRNAs altered in their expression and 24 miRNAs differently edited in human brain compared to glioblastoma tissues. We focused on the editing site within the miR-589–3p seed. MiR-589–3p is a unique miRNA almost fully edited (∼100%) in normal brain and with a consistent editing decrease in glioblastoma. The edited version of miR-589–3p inhibits glioblastoma cell proliferation, migration and invasion, while the unedited version boosts cell proliferation and motility/invasion, thus being a potential cancer-promoting factor. We demonstrated that the editing of this miRNA is mediated by ADAR2, and retargets miR-589–3p from the tumor-suppressor PCDH9 to ADAM12, which codes for the metalloproteinase 12 promoting glioblastoma invasion. Overall, our study dissects the role of a unique brain-specific editing site within miR-589–3p, with important anticancer features, and highlights the importance of RNA editing as an essential player not only for diversifying the genomic message but also for correcting not-tolerable/critical genomic coding sites.

ADAM12 is a circulating marker for stromal activation in pancreatic cancer and predicts response to chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) is characterized by abundant stroma that harbors tumor-promoting properties. No good biomarkers exist to monitor the effect of stromal targeting therapies or to predict response. We set out to identify such non-invasive markers for PDAC stroma and predict response to therapy. Gene expression datasets, co-culture experiments, xenografts, and patient samples were analyzed. Serum samples were measured from a cohort of 58 resected patients, and 87 metastatic or locally advanced PDAC patients. Baseline and follow-up levels were assessed in 372 additional metastatic PDAC patients who received nab-paclitaxel with gemcitabine (n = 184) or gemcitabine monotherapy (n = 188) in the phase III MPACT trial. Increased levels of ADAM12 were found in PDAC patients compared to healthy controls (p < 0.0001, n = 157 and n = 38). High levels of ADAM12 significantly associated with poor outcome in resected PDAC (HR 2.07, p = 0.04). In the MPACT trial survival was significantly longer for patients who received nab-paclitaxel and had undetectable ADAM12 levels before treatment (OS 12.3 m vs 7.9 m p = 0.0046). Consistently undetectable or decreased ADAM12 levels during treatment significantly associated with longer survival as well (OS 14.4 m and 11.2 m, respectively vs 8.3, p = 0.0054). We conclude that ADAM12 is a blood-borne proxy for stromal activation, the levels of which have prognostic significance and correlate with treatment benefit.

Both Autocrine Signaling and Paracrine Signaling of HB-EGF Enhance Ocular Neovascularization

OBJECTIVE

The incidence of blindness is increasing because of the increase in abnormal ocular neovascularization. Anti-VEGF (vascular endothelial growth factor) therapies have led to good results, although they are not a cure for the blindness. The purpose of this study was to determine what role HB-EGF (heparin-binding epidermal growth factor-like growth factor) plays in ocular angiogenesis.

APPROACH AND RESULTS

We examined the role played by HB-EGF in ocular neovascularization in 2 animal models of neovascularization: laser-induced choroidal neovascularization (CNV) and oxygen-induced retinopathy. We also studied human retinal microvascular endothelial cells in culture. Our results showed that the neovascularization was decreased in both the CNV and oxygen-induced retinopathy models in HB-EGF conditional knockout mice compared with that in wild-type mice. Moreover, the expressions of HB-EGF and VEGF were increased after laser-induced CNV and oxygen-induced retinopathy, and their expression sites were located around the neovascular areas. Exposure of human retinal microvascular endothelial cells to HB-EGF and VEGF increased their proliferation and migration, and CRM-197 (cross-reactive material-197), an HB-EGF inhibitor, decreased the HB-EGF-induced and VEGF-induced cell proliferation and migration. VEGF increased the expression of HB-EGF mRNA. VEGF-dependent activation of EGFR (epidermal growth factor receptor)/ERK1/2 (extracellular signal-regulated kinase 1/2) signaling and cell proliferation of endothelial cells required stimulation of the ADAM17 (a disintegrin and metalloprotease) and ADAM12. CRM-197 decreased the grades of the fluorescein angiograms and size of the CNV areas in marmoset monkeys.

CONCLUSIONS

These findings suggest that HB-EGF plays an important role in the development of CNV. Therefore, further investigations of HB-EGF are needed as a potential therapeutic target in the treatment of exudative age-related macular degeneration.

ADAM12 Is a Novel Regulator of Tumor Angiogenesis via STAT3 Signaling

ADAM12, (ADisintegrin and metalloproteinase domain-containing protein 12), is upregulated in epithelial cancers and contributes to increased tumor proliferation, metastasis, and endocrine resistance. However, its role in tumor angiogenesis is unknown. Here, we report that ADAM12 is upregulated in the vessels of aggressive breast tumors and exerts key regulatory functions. ADAM12 significantly increases bFGF-mediated angiogenesis in vivo and ADAM12 levels are upregulated in tumors that have undergone a switch to the angiogenic phenotype. Importantly, ADAM12-overexpressing breast tumors display a higher microvessel density (MVD). Our goal was to identify the mechanisms by which tumor-associated ADAM12 promotes angiogenesis. ADAM12 expression in breast tumor cells correlated with a significant upregulation of proangiogenic factors such as VEGF and MMP-9 and downregulation of antiangiogenic factors such as Thrombospondin-1 (THBS1/TSP1) and Tissue Inhibitor of Metalloproteinases-2 (TIMP-2). Co-culture with ADAM12-expressing tumor cells promoted endothelial cell (EC) recruitment and capillary tube formation. Conversely, downregulation of endogenous ADAM12 in breast cancer cell lines resulted in reduction of pro-angiogenic factors and EC recruitment. These ADAM12-mediated effects are driven by the activation of EGFR, STAT3 and Akt signaling. Blockade of EGFR/STAT3 or silencing of ADAM12 reversed the proangiogenic tumor phenotype, significantly downregulated pro-angiogenic mitogens and reduced EC recruitment. In human breast cancer tissues, ADAM12 expression was significantly positively correlated with pro-angiogenic factors including VEGF and MMP-9 but negatively associated with TSP1.Implications: These novel findings suggest that ADAM12 regulates EC function and facilitates a proangiogenic microenvironment in a STAT3-dependent manner. A combined approach of targeting ADAM12 and STAT3 signaling in breast cancer may represent a promising strategy to inhibit tumor neovascularization. Mol Cancer Res; 15(11); 1608-22. ©2017 AACR.

Upregulation of ADAM12 contributes to accelerated cell proliferation and cell adhesion-mediated drug resistance (CAM-DR) in Non-Hodgkin's Lymphoma

OBJECTIVE

ADAM12 is a member of a disintegrin and metalloproteinase family and has been reported to participate in the development of variety of tumors. However, the role of ADAM12 in Non-Hodgkin Lymphoma (NHL) has not been investigated. The present study was undertaken to determine the expression and biologic function of ADAM12 in human NHL.

METHODS

First, we constructed a model of cell adhesion in NHL, the mRNA, and protein level of ADAM12 in suspension and the adhesion model was analyzed by RT-PCR and western blot. Then, flow cytometry assay and western blot were used to investigate the mechanism of ADAM12 in the proliferation of NHL cells. In vitro, after using siRNA interfering ADAM12 expression, we performed adhesion assay and cell viability assay to determine the effect of ADAM12 on adhesive rate and drug sensitivity.

RESULTS

ADAM12 was lowly expressed in suspended cells and highly expressed in adherent NHL cells. In addition, ADAM12 was positively correlated with the proliferation and apoptosis of NHL cells by regulating the expression of p-AKT and p-GSK-3β. Furthermore, ADAM12 promoted cell adhesion-mediated drug resistance (CAM-DR) in DLBCL via AKT signaling pathway.

CONCLUSION AND DISCUSSION

Our data support a role for ADAM12 in NHL cell proliferation, adhesion, and drug resistance, and it may pave the way for a novel therapeutic approach for CAM-DR in NHL.

miR-135b suppresses tumorigenesis in glioblastoma stem-like cells impairing proliferation, migration and self-renewal

Glioblastoma multiforme (GBM) is the most common and fatal malignant adult primary brain tumor. Currently, the overall prognosis for GBM patients remains poor despite advances in neurosurgery and adjuvant treatments. MicroRNAs (miRNAs) contribute to the pathogenesis of various types of tumor, including GBM. In this study we analyzed the expression of a panel of miRNAs, which are known to be differentially expressed by the brain and GBM tumor, in a collection of patient-derived GBM stem-like cells (GSCs). Notably, the average expression level of miR-135b, was the most downregulated compared to its normal counterpart, suggesting a potential role as anti-oncogene.

Restoration of miR-135b in GSCs significantly decreased proliferation, migration and clonogenic abilities. More importantly, miR-135b restoration was able to significantly reduce brain infiltration in mouse models of GBM obtained by intracerebral injection of GSC lines. We identified ADAM12 and confirmed SMAD5 and GSK3β as miR-135b targets and potential mediators of its effects. The whole transcriptome analysis ascertained that the expression of miR-135b downmodulated additional genes driving key pathways in GBM survival and infiltration capabilities.

Our results identify a critical role of miR-135b in the regulation of GBM development, suggesting that miR-135b might act as a tumor-suppressor factor and thus providing a potential candidate for the treatment of GBM patients.

ADAM9 Expression Is Associate with Glioma Tumor Grade and Histological Type, and Acts as a Prognostic Factor in Lower-Grade Gliomas

The A disintegrin and metalloproteinase 9 (ADAM9) protein has been suggested to promote carcinoma invasion and appears to be overexpressed in various human cancers. However, its role has rarely been investigated in gliomas and, thus, in the current study we have evaluated ADAM9 expression in gliomas and examined the relevance of its expression in the prognosis of glioma patients. Clinical characteristics, RNA sequence data, and the case follow-ups were reviewed for 303 patients who had histological, confirmed gliomas. The ADAM9 expression between lower-grade glioma (LGG) and glioblastoma (GBM) patients was compared and its association with progression-free survival (PFS) and overall survival (OS) was assessed to evaluate its prognostic value. Our data suggested that GBM patients had significantly higher expression of ADAM9 in comparison to LGG patients (p < 0.001, t-test). In addition, among the LGG patients, aggressive astrocytic tumors displayed significantly higher ADAM9 expression than oligodendroglial tumors (p < 0.001, t-test). Moreover, high ADAM9 expression also correlated with poor clinical outcome (p < 0.001 and p < 0.001, log-rank test, for PFS and OS, respectively) in LGG patients. Further, multivariate analysis suggested ADAM9 expression to be an independent marker of poor survival (p = 0.002 and p = 0.003, for PFS and OS, respectively). These results suggest that ADAM9 mRNA expression is associated with tumor grade and histological type in gliomas and can serve as an independent prognostic factor, specifically in LGG patients.

Metalloproteinases ADAM12 and MMP-14 are associated with cavernous sinus invasion in pituitary adenomas

Invasion of tumor cells critically depends on cell-cell or cell-extracellular matrix interactions. Enzymes capable of modulating these interactions belong to the proteinase families of ADAM (a disintegrin and metalloprotease) and MMP (matrix metalloprotease) proteins. Our objective is to examine their expression levels and evaluate the relationship between expression levels and cavernous sinus invasion in pituitary adenomas. Tissue samples from 35 patients with pituitary adenomas were analyzed. Quantitative real-time polymerase chain reaction (qPCR) was employed to assess mRNA expression levels for ADAM and MMP genes. Protein levels were examined using immunohistochemistry and Western Blot. Correlation analyses between expression levels and clinical parameters were performed. By silencing ADAM12 and MMP-14 with siRNA in a mouse pituitary adenoma cell line (TtT/GF), their cellular effects were investigated. In our study, nine women and 26 men were included, with a mean age of 53.1 years (range 15-84 years) at the time of surgery. There were 19 cases with cavernous sinus invasion. The proteins ADAM12 and MMP-14 were significantly up-regulated in invasive adenomas compared to noninvasive adenomas. Both human isoforms of ADAM12 (ADAM12L and ADAM12s) were involved in tumor invasion; moreover, ADAM12L was found to correlate positively with Ki-67 proliferation index in pituitary adenomas. In TtT/GF pituitary adenoma cells, silencing of ADAM12 and MMP-14 significantly inhibited cell invasion and migration, respectively, whereas only silencing of ADAM12 suppressed cell proliferation. We conclude that ADAM12 and MMP-14 are associated with cavernous sinus invasion in pituitary adenomas, which qualifies these proteins in diagnosis and therapy.

ADAMs family and relatives in cardiovascular physiology and pathology

A disintegrin and metalloproteinases (ADAMs) are a family of membrane-bound proteases. ADAM-TSs (ADAMs with thrombospondin domains) are a close relative of ADAMs that are present in soluble form in the extracellular space. Dysregulated production or function of these enzymes has been associated with pathologies such as cancer, asthma, Alzheimer's and cardiovascular diseases. ADAMs contribute to angiogenesis, hypertrophy and apoptosis in a stimulus- and cell type-dependent manner. Among the ADAMs identified so far (34 in mouse, 21 in human), ADAMs 8, 9, 10, 12, 17 and 19 have been shown to be involved in cardiovascular development or cardiomyopathies; and among the 19 ADAM-TSs, ADAM-TS1, 5, 7 and 9 are important in development of the cardiovascular system, while ADAM-TS13 can contribute to vascular disorders. Meanwhile, there remain a number of ADAMs and ADAM-TSs whose function in the cardiovascular system has not been yet explored. The current knowledge about the role of ADAMs and ADAM-TSs in the cardiovascular pathologies is still quite limited. The most detailed studies have been performed in other cell types (e.g. cancer cells) and organs (nervous system) which can provide valuable insight into the potential functions of ADAMs and ADAM-TSs, their mechanism of action and therapeutic potentials in cardiomyopathies. Here, we review what is currently known about the structure and function of ADAMs and ADAM-TSs, and their roles in development, physiology and pathology of the cardiovascular system.

The EGFR-HER2 module: a stem cell approach to understanding a prime target and driver of solid tumors

The epidermal growth factor receptor (EGFR) and a coreceptor denoted HER2/ERBB2 are frequently overexpressed or mutated in solid tumors, such as carcinomas and gliomas. In line with driver roles, cancer drugs intercepting EGFR or HER2 currently outnumber therapies targeting other hubs of signal transduction. To explain the roles for EGFR and HER2 as prime drivers and targets, we take lessons from invertebrates and refer to homeostatic regulation of several mammalian tissues. The model we infer ascribes to the EGFR-HER2 module pivotal functions in rapid clonal expansion of progenitors called transient amplifying cells (TACs). Accordingly, TACs of tumors suffer from replication stress, and hence accumulate mutations. In addition, several lines of evidence propose that in response to EGF and related mitogens, TACs might undergo dedifferentiation into tissue stem cells, which might enable entry of oncogenic mutations into the stem cell compartment. According to this view, antibodies or kinase inhibitors targeting EGFR-HER2 effectively retard some solid tumors because they arrest mutation-enriched TACs and possibly inhibit their dedifferentiation. Deeper understanding of the EGFR-HER2 module and relations between cancer stem cells and TACs will enhance our ability to control a broad spectrum of human malignancies.

The Disintegrin and Metalloprotease ADAM12 Is Associated with TGF-β-Induced Epithelial to Mesenchymal Transition

The increased expression of the Disintegrin and Metalloprotease ADAM12 has been associated with human cancers, however its role remain unclear. We have previously reported that ADAM12 expression is induced by the transforming growth factor, TGF-β and promotes TGF-β-dependent signaling through interaction with the type II receptor of TGF-β. Here we explore the implication of ADAM12 in TGF-β-mediated epithelial to mesenchymal transition (EMT), a key process in cancer progression. We show that ADAM12 expression is correlated with EMT markers in human breast cancer cell lines and biopsies. Using a non-malignant breast epithelial cell line (MCF10A), we demonstrate that TGF-β-induced EMT increases expression of the membrane-anchored ADAM12L long form. Importantly, ADAM12L overexpression in MCF10A is sufficient to induce loss of cell-cell contact, reorganization of actin cytoskeleton, up-regulation of EMT markers and chemoresistance. These effects are independent of the proteolytic activity but require the cytoplasmic tail and are specific of ADAM12L since overexpression of ADAM12S failed to induce similar changes. We further demonstrate that ADAM12L-dependent EMT is associated with increased phosphorylation of Smad3, Akt and ERK proteins. Conversely, inhibition of TGF-β receptors or ERK activities reverses ADAM12L-induced mesenchymal phenotype. Together our data demonstrate that ADAM12L is associated with EMT and contributes to TGF-β-dependent EMT by favoring both Smad-dependent and Smad-independent pathways.

The role of proteases in regulating Eph/ephrin signaling

Proteases regulate a myriad of cell functions, both in normal and disease states. In addition to protein turnover, they regulate a range of signaling processes, including those mediated by Eph receptors and their ephrin ligands. A variety of proteases is reported to directly cleave Ephs and/or ephrins under different conditions, to promote receptor and/or ligand shedding, and regulate receptor/ligand internalisation and signaling. They also cleave other adhesion proteins in response to Eph-ephrin interactions, to indirectly facilitate Eph-mediated functions. Proteases thus contribute to Eph/ephrin mediated changes in cell-cell and cell-matrix interactions, in cell morphology and in cell migration and invasion, in a manner which appears to be tightly regulated by, and co-ordinated with, Eph signaling. This review summarizes the current literature describing the function and regulation of protease activities during Eph/ephrin-mediated cell signaling.

ADAM12 is a prognostic factor associated with an aggressive molecular subtype of high-grade serous ovarian carcinoma

ADAM metallopeptidase domain 12 (ADAM12) is a promising biomarker because of its low expression in normal tissues and high expression in a variety of human cancers. However, ADAM12 levels in ovarian cancer have not been well characterized. We previously identified ADAM12 as one of the signature genes associated with poor survival in high-grade serous ovarian carcinoma (HGSOC). Here, we sought to determine if high levels of the ADAM12 protein and/or messenger RNA (mRNA) are associated with clinical variables in HGSOC. We show that high protein levels of ADAM12 in banked preoperative sera are associated with shorter progression-free and overall survival. Tumor levels of ADAM12 mRNA were also associated with shorter progression-free and overall survival as well as with lymphatic and vascular invasion, and residual tumor volume following cytoreductive surgery. The majority of genes co-expressed with ADAM12 in HGSOC were transforming growth factor (TGF)β signaling targets that function in collagen remodeling and cell-matrix adhesion. In tumor sections, the ADAM12 protein and mRNA were expressed in epithelial cancer cells and surrounding stromal cells. In vitro data showed that ADAM12 mRNA levels can be increased by TGFβ signaling and direct contact between epithelial and stromal cells. High tumor levels of ADAM12 mRNA were characteristic of the mesenchymal/desmoplastic molecular subtype of HGSOC, which is known to have the poorest prognosis. Thus, ADAM12 may be a useful biomarker of aggressive ovarian cancer for which standard treatment is not effective.

Effects of nitric oxide synthase deficiency on a disintegrin and metalloproteinase domain-containing protein 12 expression in mouse brain samples

A disintegrin and metalloproteinase domain-containing protein 12 (ADAM12) belongs to the ADAM family of transmembrane proteins. Via proteolysis, cell adhesion, cell-cell fusion, cell-matrix interaction and membrane protein shedding, ADAM proteins are involved in normal brain development, and also in cancer genesis and progression, and in inflammation. Therefore, neurobiological research focusing on this protein is increasing. Nitric oxide (NO), which is endogenously produced by NO synthases (NOS), is associated with glial tumors. However, knock-out of NOS produces only limited antitumor effects. The present study analyzed the expression of ADAM12 in the cortex and hippocampus of C57/BL6 wild-type mice, and endothelial NOS-, neuronal NOS-(nNOS) or inducible NOS (iNOS)-deficient (-/-) mice, at different stages of development. Expression of ADAM12 was quantified using immunoblot analysis of cortical and hippocampal tissue samples from fetal, neonatal (5 days postnatal), adult (12 weeks old) or >1 year old mice. Using reverse transcription-quantitative polymerase chain reaction, ADAM12 expression was analyzed in cultured N9, OLN93, C6 and PC12 cells, representing the four main cell types in the brain, following NOS inhibition. ADAM12 expression was low in all mouse genotypes and regions of the brain, and in fetal and neonatal mice, an increase in expression was observed with increasing age. The highest levels of expression were observed in the cortex of adult mice, iNOS(-/-) mice of >1 year and wild-type mice, and in the hippocampus of adult and iNOS(-/-) mice of >1 year. By contrast, ADAM12 expression was lowest in adult nNOS(-/-) mice. Inhibition of NOS using N(ω)-Nitro-L-arginine methyl ester hydrochloride, induced ADAM12 mRNA expression in N9 and PC12 cell lines. Inhibition of NOS using L-N(6)-(1-Iminoethyl)lysine dihydrochloride, induced ADAM12 mRNA expression in N9 and C6 cell lines. No change in ADAM12 expression was observed in OLN93 cells following NOS inhibition. ADAM12 expression in mouse hippocampus and cortex samples demonstrated considerable variation during development, with a marked increase observed in adult and >1 year old mice, compared with that in fetal and neonatal mice.

Expression of a-disintegrin and metalloproteinase 10 correlates with grade of malignancy in human glioma

The aim of the present study was to determine the expression of a-disintegrin and metalloproteinase 10 (ADAM10) in human glioma tissues from surgical specimens and discuss its possible significance in glioma biology. A total of 43 glioma specimens obtained from patients between 2007 and 2010 were collected and a series of assays were performed. Of these, 22 cases were low-grade gliomas, while 21 cases were high-grade gliomas. In addition, 20 cases of meningioma were used as the control group. Reverse transcription-polymerase chain reaction (RT-PCR), western blot analysis and immunohistochemistry were used to determine the mRNA and protein expression levels of ADAM10. Besides the quantitative analysis, histological observations were also performed to localize ADAM10 expression in glioma cells. The RT-PCR and western blot analysis results demonstrated increased ADAM10 expression in the low-grade glioma samples compared with the control (P<0.05), while ADAM10 expression was further increased in the high-grade glioma samples (P<0.01 vs. control; P<0.05 vs. low-grade glioma), indicating that the mRNA and protein expression levels of ADAM10 were malignancy-dependent. The immunohistochemical analysis revealed that the ADAM10 protein was located on both the tumor cell membrane and blood vessel walls within tumor tissues. In conclusion, these results indicated that ADAM10 expression correlates with the grade of malignancy in human glioma from surgical specimens. In addition, the fact that ADAM10 protein was expressed on cell membranes and blood vessel walls within tumor tissues, indicates that its expression may be associated with invasive tumor growth and peritumoral edema formation.

ADAM-9 is a novel mediator of tenascin-C-stimulated invasiveness of brain tumor-initiating cells

BACKGROUND

Tenascin-C (TNC), an extracellular matrix protein overexpressed in malignant gliomas, stimulates invasion of conventional glioma cell lines (U251, U87). However, there is a dearth of such information on glioma stemlike cells. Here, we have addressed whether and how TNC may regulate the invasiveness of brain tumor-initiating cells (BTICs) that give rise to glioma progenies.

METHODS

Transwell inserts coated with extracellular matrix proteins were used to determine the role of TNC in BTIC invasion. Microarray analysis, lentiviral constructs, RNA interference-mediated knockdown, and activity assay ascertained the role of proteases in TNC-stimulated BTIC invasion in culture. Involvement of proteases was validated using orthotopic brain xenografts in mice.

RESULTS

TNC stimulated BTIC invasiveness in a metalloproteinase-dependent manner. A global gene expression screen identified the metalloproteinase ADAM-9 as a potential regulator of TNC-stimulated BTIC invasiveness, and this was corroborated by an increase of ADAM-9 protein in 4 glioma patient-derived BTIC lines. Notably, RNA interference to ADAM-9, as well as inhibition of mitogen-activated protein kinase 8 (c-Jun NH2-terminal kinase), attenuated TNC-stimulated ADAM-9 expression, proteolytic activity, and BTIC invasiveness. The relevance of ADAM-9 to tumor invasiveness was validated using resected human glioblastoma specimens and orthotopic xenografts where elevation of ADAM-9 and TNC expression was prominent at the invasive front of the tumor.

CONCLUSIONS

This study has identified TNC as a promoter of the invasiveness of BTICs through a mechanism involving ADAM-9 proteolysis via the c-Jun NH2-terminal kinase pathway.

Urinary ADAM12 and MMP-9/NGAL complex detect the presence of gastric cancer

Although the early diagnosis of gastric cancer provides the opportunity for curative endoscopic resection, comprehensive screening endoscopy would be invasive and expensive. To date, there is a complete absence of clinically useful gastric cancer biomarkers. With the goal of discovering noninvasive biomarkers for the early diagnosis of gastric cancer, we have conducted a case-control study using urine samples from individuals with gastric cancer versus healthy control samples. Of the enrolled 106 patients from September, 2012 to April, 2013, a cohort of 70 patients composed of 35 patients with gastric cancer and 35 age- and sex-matched healthy controls was analyzed. The gastric cancer group was composed of stage IA of 62.9% (22/35). The urinary levels of MMP-9/NGAL complex (uMMP-9/NGAL) and ADAM12 (uADAM12) were significantly higher in the gastric cancer group compared with the healthy control group as determined by monospecific ELISAs (uMMP-9/NGAL: median, 85 pg/mL vs. 0 pg/mL; P = 0.020; uADAM12: median, 3.35 ng/mL vs. 1.44 ng/mL; P < 0.001). Multivariate analysis demonstrated that both uMMP-9/NGAL and uADAM12 were significant, independent diagnostic biomarkers for gastric cancer. Moreover, MMP-9/NGAL activity was significantly elevated as determined by gelatin zymography. The combination of uMMP-9/NGAL with uADAM12 distinguished between control samples and gastric cancer samples with an AUC of 0.825 (P < 0.001) in an ROC analysis. Significantly, immunohistochemical analyses demonstrated a high coexpression of MMP-9 and NGAL (P < 0.001) and high expression of ADAM12 (P < 0.001) in gastric cancer tissues compared with adjacent normal tissues (N = 35). In summary, uMMP-9/NGAL and uADAM12 are potential noninvasive biomarkers for gastric cancer, including early-stage disease.

N-glycosylation regulates ADAM8 processing and activation

The transmembrane ADAM8 (A Disintegrin And Metalloproteinase 8) protein is abundantly expressed in human breast tumors and derived metastases compared with normal breast tissue, and plays critical roles in aggressive Triple-Negative breast cancers (TNBCs). During ADAM8 maturation, the inactive proform dimerizes or multimerizes and autocatalytically removes the prodomain leading to the formation of the active, processed form. ADAM8 is a glycoprotein; however, little was known about the structure or functional role of these sugar moieties. Here, we report that in estrogen receptor (ER)α-negative, but not -positive, breast cancer cells ADAM8 contains N-glycosylation, which is required for its correct processing and activation. Consistently ADAM8 dimers were detected on the surface of ERα-negative breast cancer cells but not on ERα-positive ones. Site-directed mutagenesis confirmed four N-glycosylazhytion sites (Asn-67, Asn-91, Asn-436, and Asn-612) in human ADAM8. The Asn-67 and Asn-91 prodomain sites contained high mannose, whereas complex type N-glycosylation was observed on Asn-436 and Asn-612 in the active and remnant forms. The Asn-91 and Asn-612 sites were essential for its correct processing and cell surface localization, in particular its exit from the Golgi and endoplasmic reticulum, respectively. The N436Q mutation led to decreased ADAM8 stability due to enhanced lysosomal degradation. In contrast, mutation of the Asn-67 site had only modest effects on enzyme stability and processing. Thus, N-glycosylation is essential for processing, localization, stability, and activity of ADAM8.

Erbb2 up-regulation of ADAM12 expression accelerates skin cancer progression

Solar ultraviolet (UV) radiation can cause severe damage to the skin and is the primary cause of most skin cancer. UV radiation causes DNA damage leading to mutations and also activates the Erbb2/HER2 receptor through indirect mechanisms involving reactive oxygen species. We hypothesized that Erbb2 activation accelerates the malignant progression of UV-induced skin cancer. Following the induction of benign squamous papillomas by UV exposure of v-ras(Ha) transgenic Tg.AC mice, mice were treated topically with the Erbb2 inhibitor AG825 and tumor progression monitored. AG825 treatment reduced tumor volume, increased tumor regression, and delayed the development of malignant squamous cell carcinoma (SCC). Progression to malignancy was associated with increased Erbb2 and ADAM12 (A Disintegin And Metalloproteinase 12) transcripts and protein, while inhibition of Erbb2 blocked the increase in ADAM12 message upon malignant progression. Similarly, human SCC and SCC cell lines had increased ADAM12 protein and transcripts when compared to normal controls. To determine whether Erbb2 up-regulation of ADAM12 contributed to malignant progression of skin cancer, Erbb2 expression was modulated in cultured SCC cells using forced over-expression or siRNA targeting, demonstrating up-regulation of ADAM12 by Erbb2. Furthermore, ADAM12 transfection or siRNA targeting revealed that ADAM12 increased both the migration and invasion of cutaneous SCC cells. Collectively, these results suggest Erbb2 up-regulation of ADAM12 as a novel mechanism contributing to the malignant progression of UV-induced skin cancer. Inhibition of Erbb2/HER2 reduced tumor burden, increased tumor regression, and delayed the progression of benign skin tumors to malignant SCC in UV-exposed mice. Inhibition of Erbb2 suppressed the increase in metalloproteinase ADAM12 expression in skin tumors, which in turn increased migration and tumor cell invasiveness.

p75 neurotrophin receptor cleavage by α- and γ-secretases is required for neurotrophin-mediated proliferation of brain tumor-initiating cells

Malignant gliomas are highly invasive, proliferative, and resistant to treatment. Previously, we have shown that p75 neurotrophin receptor (p75NTR) is a novel mediator of invasion of human glioma cells. However, the role of p75NTR in glioma proliferation is unknown. Here we used brain tumor-initiating cells (BTICs) and show that BTICs express neurotrophin receptors (p75NTR, TrkA, TrkB, and TrkC) and their ligands (NGF, brain-derived neurotrophic factor, and neurotrophin 3) and secrete NGF. Down-regulation of p75NTR significantly decreased proliferation of BTICs. Conversely, exogenouous NGF stimulated BTIC proliferation through α- and γ-secretase-mediated p75NTR cleavage and release of its intracellular domain (ICD). In contrast, overexpression of the p75NTR ICD induced proliferation. Interestingly, inhibition of Trk signaling blocked NGF-stimulated BTIC proliferation and p75NTR cleavage, indicating a role of Trk in p75NTR signaling. Further, blocking p75NTR cleavage attenuated Akt activation in BTICs, suggesting role of Akt in p75NTR-mediated proliferation. We also found that p75NTR, α-secretases, and the four subunits of the γ-secretase enzyme were elevated in glioblastoma multiformes patients. Importantly, the ICD of p75NTR was commonly found in malignant glioma patient specimens, suggesting that the receptor is activated and cleaved in patient tumors. These results suggest that p75NTR proteolysis is required for BTIC proliferation and is a novel potential clinical target.

ADAM-12 as a diagnostic marker for the proliferation, migration and invasion in patients with small cell lung cancer

Small cell lung cancer (SCLC) is highly aggressive and is characterized by malignant metastasis. Approximately 90% of patients die due to extensive metastasis. The extracellular matrix (ECM) is a natural barrier that can prevent cellular invasion and metastasis. Therefore, degradation of the ECM must take place in order for extensive metastasis to occur. A disintegrin and metalloprotease (ADAM) is a multi-domain protease that plays an important role in tumorigenesis, as well as tumor development, invasion and metastasis. However, there have been few reports on the expression and role of ADAMs in SCLC. In the current study, the expression and role of ADAMs in SCLC proliferation, invasion and metastasis was investigated. A total of 150 SCLC tissue samples were examined by immunohistochemistry for ADAMs expression. ADAM-12 was found to be abundantly expressed in 72.67% samples and other ADAMs were found to be expressed in 10% to 40% of samples. ADAM-12 levels in serum and urine, from 70 SCLC patients and 40 normal controls, were also measured using ELISA. ADAM-12 expression was significantly higher in SCLC patients than in healthy controls and in patients with extensive disease compared to those with more limited disease. Silencing the expression of ADAM-12 in H1688 cells through the use of specific siRNA significantly reduced cellular proliferation, invasion and metastasis. Supplementing the expression of ADAM-12-L or -S in H345 cells, significantly enhanced cellular proliferation, invasion and metastasis. Animal models with metastatic SCLC also exhibited increased expression of ADAM-12 along with enhanced invasion and metastasis. In brief, ADAM-12 is an independent prognostic factor and diagnostic marker, and is involved in the proliferation, invasion and metastasis of SCLC.

Cellular reprogramming into a brown adipose tissue-like phenotype by co-expression of HB-EGF and ADAM 12S

Abnormal adipogenesis leads to excessive fat accumulation and several health disorders. Mouse fibroblasts (MLC) transfected with ADAM 12S and HB-EGF promoted lipid accumulation. Addition of KBR-7785, an ADAM 12S inhibitor, to HB-EGF/ADAM 12S expressing cells suppressed adipogenesis. BrdU incorporation was attenuated and enhanced mitotracker staining was observed in HB-EGF/ADAM 12S cells. Quantitative real time RT-PCR resulted in elevated levels of expression of three brown adipose tissue (BAT) genes (PRDM16, PGC-1α, and UCP-1), while expression levels of the three white adipose tissue (WAT) genes (PPARγ, C/EBPα, and AKT-1) were unaltered in HB-EGF/ADAM 12S cells. Amino- or carboxy-terminal deletions of HB-EGF (HB-EGFΔN and HB-EGFΔC) co-expressed with ADAM 12S stimulated lipid accumulation. Human epidermoid carcinoma cells (A431) also exhibited lipid accumulation by HB-EGF/ADAM 12S co-expression. These studies suggest ADAM 12S and HB-EGF are involved in cellular plasticity resulting in the production of BAT-like cells and offers insight into novel therapeutic approaches for fighting obesity.

Alternative mRNA splicing generates two distinct ADAM12 prodomain variants

Human ADAM12, transcript variant 1 (later on referred to as Var-1b), present in publicly available databases contains the sequence 5′-GTAATTCTG-3′ at the nucleotide positions 340–348 of the coding region, at the 3′ end of exon 4. The translation product of this variant, ADAM12-Lb, includes the three amino acid motif ¹¹⁴VIL¹¹⁶ in the prodomain. This motif is not conserved in ADAM12 from different species and is not present in other human ADAMs. Currently, it is not clear whether a shorter variant, Var-1a, encoding the protein version without the ¹¹⁴VIL¹¹⁶ motif, ADAM12-La, is expressed in human. In this work, we have established that human mammary epithelial cells and breast cancer cells express both Var-1a and Var-1b transcripts. Importantly, the proteolytic processing and intracellular trafficking of the corresponding ADAM12-La and ADAM12-Lb proteins are different. While ADAM12-La is cleaved and trafficked to the cell surface in a manner similar to ADAM12 in other species, ADAM12-Lb is retained in the ER and is not proteolytically processed. Furthermore, the relative abundance of ADAM12-La and ADAM12-Lb proteins detected in several breast cancer cell lines varies significantly. We conclude that the canonical form of transmembrane ADAM12 is represented by Var-1a/ADAM12-La, rather than Var-1b/ADAM12-Lb currently featured in major sequence databases.

ADAM12 is expressed in the tumour vasculature and mediates ectodomain shedding of several membrane-anchored endothelial proteins

ADAM (a disintegrin and metalloproteinase) 12 is a metalloprotease implicated in cancer progression. ADAM12 can activate membrane-anchored proteins, such as sonic hedgehog, Delta-like 1 and certain epidermal growth factor receptor ligands, through a process called ectodomain shedding. We screened several membrane-anchored proteins to further dissect the substrate profile of ADAM12-mediated ectodomain shedding, and found shedding of five previously unreported substrates [Kitl1, VE-cadherin (vascular endothelial cadherin), Flk-1 (fetal liver kinase 1), Tie-2, and VCAM-1 (vascular cell adhesion molecule 1)], of which the latter four are specifically expressed by endothelial cells. We also observed that ADAM12 expression was increased in the tumour vasculature of infiltrating ductal carcinoma of the human breast as compared with little to no expression in normal breast tissue vasculature, suggesting a role for ADAM12 in tumour vessels. These results prompted us to further evaluate ADAM12-mediated shedding of two endothelial cell proteins, VE-cadherin and Tie-2. Endogenous ADAM12 expression was very low in cultured endothelial cells, but was significantly increased by cytokine stimulation. In parallel, the shed form of VE-cadherin was elevated in such cytokine-stimulated endothelial cells, and ADAM12 siRNA (small interfering RNA) knockdown reduced cytokine-induced shedding of VE-cadherin. In conclusion, the results of the present study demonstrate a role for ADAM12 in ectodomain shedding of several membrane-anchored endothelial proteins. We speculate that this process may have importance in tumour neovascularization or/and tumour cell extravasation.

Notch increases the shedding of HB-EGF by ADAM12 to potentiate invadopodia formation in hypoxia

Hypoxia increases the levels of ADAM12 in a Notch-dependent manner, leading to increased ectodomain shedding of HB-EGF and subsequent promotion of invadopodia formation.

Notch regulates cell–cell contact-dependent signaling and is activated by hypoxia, a microenvironmental condition that promotes cellular invasion during both normal physiology and disease. The mechanisms by which hypoxia and Notch regulate cellular invasion are not fully elucidated. In this paper, we show that, in cancer cells, hypoxia increased the levels and activity of the ADAM12 metalloprotease in a Notch signaling–dependent manner, leading to increased ectodomain shedding of the epidermal growth factor (EGF) receptor (EGFR) ligand heparin-binding EGF-like growth factor. Released HB-EGF induced the formation of invadopodia, cellular structures that aid cancer cell invasion. Thus, we describe a signaling pathway that couples cell contact–dependent signaling with the paracrine activation of the EGFR, indicating cross talk between the Notch and EGFR pathways in promoting cancer cell invasion. This signaling pathway might regulate the coordinated acquisition of invasiveness by neighboring cells and mediate the communication between normoxic and hypoxic areas of tumors to facilitate cancer cell invasion.

A Disintegrin And Metalloproteinase 12 produced by tumour cells accelerates osteosarcoma tumour progression and associated osteolysis

BACKGROUND

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents for whom the prognosis remains unfavourable despite treatment protocols that combine chemotherapy and surgery. Metalloproteinases decisively contribute to cancer development and promotion by regulating cell growth, angiogenesis or inflammation. However, their role in osteosarcoma remains still unknown.

METHODS

A screening of a large panel of metalloproteinases and their inhibitors, carried out in osteolytic (K7M2 and POS-1) or osteoblastic (MOS-J) mouse osteosarcoma models, shows that a member of a family of cell surface metallopeptidases, A Disintegrin And Metalloproteinase 12 (ADAM12), is highly expressed in the K7M2 and POS-1 cell lines and weakly expressed in the MOS-J cell line. To investigate whether ADAM12, involved in several pathologic conditions characterised by abnormal cell growth, plays a role in osteosarcoma tumour growth, ADAM12 was overexpressed in MOS-J and downregulated in K7M2 cells.

RESULTS

In vivo experiments demonstrated that ADAM12 favours tumour growth, leading to a significant modification in animal survival. In vitro assays showed that ADAM12 knockdown in K7M2 cells slows cell proliferation. In addition, the study of microarchitectural parameters, assessed by micro-computed tomography (CT) analysis, showed that ADAM12 favours bone osteolysis, as demonstrated both in an ADAM12 overexpressing (MOS-J) and a knockdown (K7M2) model. Histological analysis showed that ADAM12 inhibited osteoblast activity and therefore enhanced bone resorption.

CONCLUSIONS

Our study demonstrates that ADAM12 expression not only favours tumour growth but also associates enhanced osteolysis with a significant reduction in animal survival, suggesting that ADAM12 could be a new therapeutic target in osteosarcoma.

Oral cancer diagnosis via a ferrocenylnaphthalene diimide-based electrochemical telomerase assay

BACKGROUND

Telomerase is regarded as a good marker for cancer because it is unregulated in most tumor cells compared with normal cells. We evaluated telomerase activity in the lysate of tumor tissue and surrounding cells of oral cancer patients by an electrochemical technique, dubbed the electrochemical telomerase assay (ECTA).

METHODS

The assay used ferrocenylnaphthalene diimide (FND) as the probe. Electrochemical telomerase substrate (ETS) primer immobilized on the electrode was elongated by telomerase and FND bound to the product to give rise to a current. The data were standardized with the change in current before and after the elongation, respectively.

RESULTS

The change in current increased more than 30% in biopsy samples from most cancer patients, whereas the increase was 20% or lower in most healthy individuals. On the basis of this difference individual clinical samples were judged telomerase positive, ambiguous, or negative. The positive rates in the cancerous tissues and exfoliated cells (EOCs) of the patients were 85% and 90%, respectively, whereas the corresponding values were 50% and 10% by the telomerase repeat amplification protocol. Furthermore, the positive rate for the ECTA was 100% in early tumors smaller than 2 cm, and 95% and 82% of biopsy and exfoliated cells of healthy individuals were correctly judged as negative. Fifty-six unknown samples with EOCs tested were correctly judged to be cancerous or normal in 84% of cases.

CONCLUSIONS

The ECTA yielded high hit rates for cancerous and normal cells, especially in EOCs, results indicating that this minimally invasive test is suitable for oral cancer diagnosis.