ADAM9 is highly expressed in renal cell cancer and is associated with tumour progression

Circ_0061140 Potentiates Clear Cell Renal Cell Carcinoma Progression Via the MicroRNA-126-5p/ADAM9 Axis

Circular RNAs (circRNAs) function as new cancer biomarkers, but the role of circ_0061140 remains unknown in clear cell renal cell carcinoma (ccRCC). Therefore, we aimed to validate the functions of circ_0061140 in ccRCC and its potential as a prognostic biomarker. At first, circ_0061140 expression in ccRCC tissues and cells was detected, and circ_0061140 was upregulated in ccRCC tissues (p < 0.0001) and cells (p < 0.0001). Patients with high expression of circ_0061140 had a worse prognosis (p < 0.05). Then, siRNA against circ_0061140 was transfected into Caki-1 and UT14 cells to explore its roles in the biological functions of ccRCC cells, and suppressing roles of downregulated circ_0061140 were observed in the cell growth of Caki-1 and UT14 cells (p < 0.01). Next, circ_0061140 was found to be a sponge of miR-126-5p, and ADAM9 was determined to be a target of miR-126-5p. Finally, functional rescue experiments were conducted to observe their roles in ccRCC cell growth. It was suggested that suppressed miR-126-5p or overexpressed ADAM9 induced cell proliferation and restricted cell apoptosis in ccRCC cells based on si-circ_0061140 (p < 0.01). Altogether, this study highlights that circ_0061140 plays an oncogenic role in ccRCC through modulation of the miR-126-5p/ADAM9 axis.

Overexpression of a disintegrin and metalloproteinase 9 (ADAM9) in relation to poor prognosis of patients with oral squamous cell carcinoma

This study investigates the expressions of ADAM9, CDCP1 and t-PA in OSCC and their impacts on patient prognosis. Previous research has demonstrated the overexpression of ADAM9 and activation of plasminogen activator in OSCC, but CDCP1's role remains unexplored. While these biomolecules are known to contribute to lung cancer metastasis, their concurrent expressions in OSCC have not been thoroughly examined. Our aim is to assess the expressions of ADAM9, CDCP1, and t-PA in OSCC specimens, compare them with normal oral tissues, and explore their correlation with OSCC's clinicopathological features and patient survival outcomes.

Hypoxia Promotes the Expression of ADAM9 by Tubular Epithelial Cells, Which Enhances Transforming Growth Factor β1 Activation and Promotes Tissue Fibrosis in Patients With Lupus Nephritis

OBJECTIVE

Enhanced expression of transforming growth factor (TGF) β in the kidneys of patients with lupus nephritis (LN) can lead to progressive fibrosis, resulting in end-organ damage. ADAM9 activates TGFβ1 by cleaving the latency-associated peptide (LAP). We hypothesized that ADAM9 in the kidney may accelerate fibrogenesis by activating TGFβ1.

METHODS

We assessed the expression of ADAM9 in the kidneys of mice and humans who were lupus prone. In vitro experiments were conducted using tubular epithelial cells (TECs) isolated from mice and explored the mechanisms responsible for the up-regulation of ADAM9 and the subsequent activation of TGFβ1. To assess the role of ADAM9 in the development of tubular-intestinal fibrosis in individuals with LN, we generated MRL/lpr mice who were Adam9 deficient.

RESULTS

ADAM9 was highly expressed in tubules from MRL/lpr mice. The transcription factor hypoxia-inducible factor-1α was found to promote the transcription of ADAM9 in TECs. TECs from mice who were Adam9 deficient and exposed to the hypoxia mimetic agent dimethyloxalylglycine failed to cleave the LAP to produce bioactive TGFβ1 from latent TGFβ1. Coculture of TECs from mice who were Adam9 deficient with fibroblasts in the presence of dimethyloxalylglycine and latent TGFβ1 produced decreased amounts of type I collagen and α-smooth muscle actin (SMA) by fibroblasts. MRL/lpr mice who were Adam9 deficient showed reduced interstitial fibrosis. At the translational level, ADAM9 expression in tissues and urine of patients with LN was found to increase.

CONCLUSION

Hypoxia promotes the expression of ADAM9 by TECs, which is responsible for the development of interstitial fibrosis in patients with LN by enhancing the TGFβ1 activation, which promotes fibroblasts to produce collagen and α-SMA.

An Antibody of the Secreted Isoform of Disintegrin and Metalloprotease 9 (sADAM9) Inhibits Epithelial-Mesenchymal Transition and Migration of Prostate Cancer Cell Lines

Prostate cancer (PC) is the most common cancer diagnosed in men worldwide. Currently, castration-resistant prostate cancer (CRPC), which is resistant to androgen deprivation therapy, has a poor prognosis and is a therapeutic problem. We investigated the antitumor effects on PC of an antibody neutralizing secreted disintegrin and metalloproteinase domain-containing protein 9 (sADAM9), which is a blood-soluble form. We performed proliferation assays, wound healing assays, invasion assays, Western blot (WB), and an in vivo study in which a sADAM9 neutralizing antibody was administered intratumorally to PC-bearing mice. In invasion assays, the sADAM9 neutralizing antibody significantly inhibited invasion in all cell lines (TRAMP-C2: p = 0.00776, LNCaP: p = 0.000914, PC-3: p = 0.0327, and DU145: p = 0.0254). We examined epithelial-mesenchymal transition (EMT) markers, one of the metastatic mechanisms, in WB and showed downregulation of Slug in TRAMP-C2, LNCaP, and DU145 and upregulation of E-cadherin in TRAMP-C2 and PC-3 by sADAM9 neutralization. In mouse experiments, the sADAM9 neutralizing antibody significantly suppressed tumor growth compared to controls (1.68-fold in TRAMP-C2, 1.89-fold in LNCaP, and 2.67-fold in PC-3). These results suggested that the sADAM9 neutralizing antibody inhibits invasion, migration, and tumor growth in PC. Previous studies examined the anti-tumor effect of knockdown of total ADAM9 or sADAM9, but this study used the new technology of neutralizing antibodies for sADAM9. This may be novel because there was no animal study using a neutralizing antibody for sADAM9 to see the relationship between ADAM9 expression and prostate cancer.

A disintegrin and metalloproteinase domain 9 facilitates SARS-CoV-2 entry into cells with low ACE2 expression

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of the Coronavirus disease-19 (COVID-19) pandemic, utilizes angiotensin-converting enzyme 2 (ACE2) as a receptor for virus infection. However, the expression pattern of ACE2 does not coincide with the tissue tropism of SARS-CoV-2, hinting that other host proteins might be involved in facilitating SARS-CoV-2 entry. To explore potential host factors for SARS-CoV-2 entry, we performed an arrayed shRNA screen in H1650 and HEK293T cells. Here, we identified a disintegrin and a metalloproteinase domain 9 (ADAM9) protein as an important host factor for SARS-CoV-2 entry. Our data showed that silencing ADAM9 reduced virus entry, while its overexpression promoted infection. The knockdown of ADAM9 decreased the infectivity of the variants of concern tested-B.1.1.7 (alpha), B.1.617.2 (delta), and B.1.1.529 (omicron). Furthermore, mechanistic studies indicated that ADAM9 is involved in the binding and endocytosis stages of SARS-CoV-2 entry. Through immunoprecipitation experiments, we demonstrated that ADAM9 binds to the S1 subunit of the SARS-CoV-2 Spike. Additionally, ADAM9 can interact with ACE2, and co-expression of both proteins markedly enhances virus infection. Moreover, the enzymatic activity of ADAM9 facilitates virus entry. Our study reveals an insight into the mechanism of SARS-CoV-2 virus entry and elucidates the role of ADAM9 in virus infection. IMPORTANCE COVID-19, an infectious respiratory disease caused by SARS-CoV-2, has greatly impacted global public health and the economy. Extensive vaccination efforts have been launched worldwide over the last couple of years. However, several variants of concern that reduce the efficacy of vaccines have kept emerging. Thereby, further understanding of the mechanism of SARS-CoV-2 entry is indispensable, which will allow the development of an effective antiviral strategy. Here, we identify a disintegrin and metalloproteinase domain 9 (ADAM9) protein as a co-factor of ACE2 important for SARS-CoV-2 entry, even for the variants of concern, and show that ADAM9 interacts with Spike to aid virus entry. This virus-host interaction could be exploited to develop novel therapeutics against COVID-19.

Unfavorable immunotherapy plus tyrosine kinase inhibition outcome of metastatic renal cell carcinoma after radical nephrectomy with increased ADAM9 expression

Immunotherapy plus tyrosine kinase inhibitor (IO-TKI) has become the standard first-line therapy for advanced renal cell carcinoma (RCC). However, the modest response rate of IO-TKI therapy and the absence of biomarkers limited the selection of treatment strategies for RCC patients. There were three cohorts enrolled: two from our facility (ZS-MRCC and ZS-HRRCC) and one from a clinical study (JAVELIN-101). By RNA sequencing, the expression of ADAM9 in each sample was measured. By flow cytometry and immunohistochemistry, immune infiltration and T cell function were examined. Primary outcomes were established as treatment response and progression-free survival (PFS). Patients with low-ADAM9 expression had a higher objective response rate (56.5% vs 13.6%, P = 0.01) and longer PFS in both cohorts. In the ZS-HRRCC cohort, the expression of ADAM9 was associated with increased tumor-infiltrating T cells, which was proved by immunohistochemistry (P < 0.05) and flow cytometry (Spearman's ρ = 0.42, P < 0.001). In the high-ADAM9 group, CD8⁺ and CD4⁺ T cells revealed an exhausted phenotype with decreased GZMB (Spearman's ρ =  - 0.31, P = 0.05, and Spearman's ρ =  - 0.49, P < 0.001, respectively), and fewer Macrophages were identified. A predictive RFscore was further constructed by random forest approach, involving ADAM9 and immunologic genes. Only in the subgroup with the lower RFscore did IO-TKI outperform TKI monotherapy. High-ADAM9 expression was associated with immunosuppression and IO-TKI resistance. Expression of ADAM9 was also associated with the exhaustion and dysfunction of T cells. ADAM9-based RFscore has the potential to be used as a biomarker to distinguish the optimal patient treatment methods between IO-TKI and TKI monotherapy.

VHL Ser65 mutations enhance HIF2α signaling and promote epithelial-mesenchymal transition of renal cancer cells

Background

Von Hippel-Lindau (VHL) disease is an autosomal dominant genetic neoplastic disorder caused by germline mutation or deletion of the VHL gene, characterized by the tendency to develop multisystem benign or malignant tumors. The mechanism of VHL mutants in pathogenicity is poorly understand.

Results

Here we identified heterozygous missense mutations c.193T > C and c.194C > G in VHL in several patients from two Chinese families. These mutations are predicted to cause Serine (c.193T > C) to Proline and Tryptophan (c.194C > G) substitution at residue 65 of VHL protein (p.Ser65Pro and Ser65Trp). Ser65 residue, located within the β-domain and nearby the interaction sites with hypoxia-inducing factor α (HIFα), is highly conserved among different species. We observed gain of functions in VHL mutations, thereby stabilizing HIF2α protein and reprograming HIF2α genome-wide target gene transcriptional programs. Further analysis of independent cohorts of patients with renal carcinoma revealed specific HIF2α gene expression signatures in the context of VHL Ser65Pro or Ser65Trp mutation, showing high correlations with hypoxia and epithelial-mesenchymal transition signaling activities and strong associations with poor prognosis.

Conclusions

Together, our findings highlight the crucial role of pVHL-HIF dysregulation in VHL disease and strengthen the clinical relevance and significance of the missense mutations of Ser65 residue in pVHL in the familial VHL disease.

A Disintegrin and Metalloproteinase (ADAM) Family-Novel Biomarkers of Selected Gastrointestinal (GI) Malignancies?

The global burden of gastrointestinal (GI) cancers is expected to increase. Therefore, it is vital that novel biomarkers useful for the early diagnosis of these malignancies are established. A growing body of data has linked secretion of proteolytic enzymes, such as metalloproteinases (MMPs), which destroy the extracellular matrix, to pathogenesis of GI tumours. A disintegrin and metalloproteinase (ADAM) proteins belong to the MMP family but have been proven to be unique due to both proteolytic and adhesive properties. Recent investigations have demonstrated that the expression of several ADAMs is upregulated in GI cancer cells. Thus, the objective of this review is to present current findings concerning the role of ADAMs in the pathogenesis of GI cancers, particularly their involvement in the development and progression of colorectal, pancreatic and gastric cancer. Furthermore, the prognostic significance of selected ADAMs in patients with GI tumours is also presented. It has been proven that ADAM8, 9, 10, 12, 15, 17 and 28 might stimulate the proliferation and invasion of GI malignancies and may be associated with unfavourable survival. In conclusion, this review confirms the role of selected ADAMs in the pathogenesis of the most common GI cancers and indicates their promising significance as potential prognostic biomarkers as well as therapeutic targets for GI malignancies. However, due to their non-specific nature, future research on ADAM biology should be performed to elucidate new strategies for the diagnosis of these common and deadly malignancies and treatment of patients with these diseases.

Preclinical Evaluation of IMGC936, a Next Generation Maytansinoid-based Antibody-drug Conjugate Targeting ADAM9-expressing Tumors

A disintegrin and metalloprotease (ADAM) 9 is a member of the ADAM family of multifunctional, multidomain type 1 transmembrane proteins. ADAM9 is overexpressed in many cancers, including non-small cell lung, pancreatic, gastric, breast, ovarian, and colorectal cancer, but exhibits limited expression in normal tissues. A target-unbiased discovery platform based on intact tumor and progenitor cell immunizations, followed by an immunohistochemistry screen, led to the identification of anti-ADAM9 antibodies with selective tumor-versus-normal tissue binding. Subsequent analysis revealed anti-ADAM9 antibodies were efficiently internalized and processed by tumor cells making ADAM9 an attractive target for antibody-drug conjugate development. Here, we describe the preclinical evaluation of IMGC936, a novel antibody-drug conjugate targeted against ADAM9. IMGC936 is comprised of a high-affinity humanized antibody site-specifically conjugated to DM21-C, a next-generation linker-payload that combines a maytansinoid microtubule-disrupting payload with a stable tripeptide linker, at a drug antibody ratio of approximately 2.0. Additionally, the YTE mutation (M252Y/S254T/T256E) was introduced into the CH2 domain of the antibody Fc to maximize in vivo plasma half-life and exposure. IMGC936 exhibited cytotoxicity toward ADAM9-positive human tumor cell lines, as well as bystander killing, potent antitumor activity in human cell line-derived xenograft and patient-derived xenograft tumor models, and an acceptable safety profile in cynomolgus monkeys with favorable pharmacokinetic properties. Our preclinical data provide a strong scientific rationale for the further development of IMGC936 as a therapeutic candidate for the treatment of ADAM9-positive cancers. A first-in-human study of IMGC936 in patients with advanced solid tumors has been initiated (NCT04622774).

Non-coding RNAs and glioblastoma: Insight into their roles in metastasis

Glioma, also known as glioblastoma multiforme (GBM), is the most prevalent and most lethal primary brain tumor in adults. Gliomas are highly invasive tumors with the highest death rate among all primary brain malignancies. Metastasis occurs as the tumor cells spread from the site of origin to another site in the brain. Metastasis is a multifactorial process, which depends on alterations in metabolism, genetic mutations, and the cancer microenvironment. During recent years, the scientific study of non-coding RNAs (ncRNAs) has led to new insight into the molecular mechanisms involved in glioma. Many studies have reported that ncRNAs play major roles in many biological procedures connected with the development and progression of glioma. Long ncRNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are all types of ncRNAs, which are commonly dysregulated in GBM. Dysregulation of ncRNAs can facilitate the invasion and metastasis of glioma. The present review highlights some ncRNAs that have been associated with metastasis in GBM. miRNAs, circRNAs, and lncRNAs are discussed in detail with respect to their relevant signaling pathways involved in metastasis.

Screening and Identification of Key Biomarkers in Lower Grade Glioma via Bioinformatical Analysis

Lower-grade glioma (LGG) is a common type of central nervous system tumor. Due to its complicated pathogenesis, the choice and timing of adjuvant therapy after tumor treatment are controversial. This study explored and identified potential therapeutic targets for lower-grade. The bioinformatics method was employed to identify potential biomarkers and LGG molecular mechanisms. Firstly, we selected and downloaded GSE15824, GSE50161, and GSE86574 from the GEO database, which included 40 LGG tissue and 28 normal brain tissue samples. GEO and VENN software identified of 206 codifference expressed genes (DEGs). Secondly, we applied the DAVID online software to investigate the DEG biological function and KEGG pathway enrichment, as well as to build the protein interaction visualization network through Cytoscape and STRING website. Then, the MCODE plug is used in the analysis of 22 core genes. Thirdly, the 22 core genes were analyzed with UNCLA software, of which 18 genes were associated with a worse prognosis. Fourthly, GEPIA was used to analyze the 18 selected genes, and 14 genes were found to be a significantly different expression between LGGs and normal brain tumor samples. Fifthly, hierarchical gene clustering was used to examine the 14 important gene expression differences in different histologies, as well as analysis of the KEGG pathway. Five of these genes were shown to be abundant in the natural killer cell-mediated cytokines (NKCC) and phagosome pathways. The five key genes that may be affected by the immune microenvironment play a crucial role in LGG development.

Overexpression of ADAM9 decreases radiosensitivity of hepatocellular carcinoma cell by activating autophagy

A disintegrin and a metalloprotease (ADAM)9 upregulated within human hepatocellular carcinoma (HCC) cells, but its effect on HCC radiosensitivity remains unknown. The present work aimed to examine the effect of ADAM9 on HCC radiosensitivity and to reveal its possible mechanism, which may be helpful in identifying a potential therapeutic strategy. Changes in ADAM9 expression after X-ray irradiation were identified using western blot, qRT-PCR, and immunofluorescence. ADAM9 stable knockdown and overexpression cell lines were constructed using lentivirus packaging. The radiosensitivity of HCC cells with altered ADAM9 expression was examined by CCK-8 assays, subcutaneous tumorigenesis experiments, and clone formation assays. This study also determined how autophagy affected HCC cell radiosensitivity. Furthermore, ADAM9, p62 and Bax expressions in HCC tissues that were removed after radiotherapy were detected by immunohistochemistry, and the relationship among the levels of these molecules was statistically analyzed. The level of ADAM9expression in HCC cells increased after X-ray irradiation. Through CCK-8 assays, subcutaneous tumorigenesis experiments, and clone formation assays, this work discovered the increased MHCC97H cell radiosensitivity after ADAM9 knockdown, and the radiosensitivity of Huh7 cells decreased after the overexpression of ADAM9. Furthermore, ADAM9 induced HCC cell autophagy via downregulating Nrf2 expression, while autophagy inhibition or induction reversed the effects of altered ADAM9 expression on radiosensitivity. Moreover, ADAM9 level showed a negative correlation with Bax and p62 expression within HCC tissues after radiotherapy. Taken together, ADAM9 decreased the radiosensitivity of HCC cells, and autophagy mediated this process.

Key metalloproteinase-mediated pathways in the kidney

Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases (ADAMs) belong to the metzincin family of zinc-containing multidomain molecules, and can act as soluble or membrane-bound proteases. These enzymes inactivate or activate other soluble or membrane-expressed mediator molecules, which enables them to control developmental processes, tissue remodelling, inflammatory responses and proliferative signalling pathways. The dysregulation of MMPs and ADAMs has long been recognized in acute kidney injury and in chronic kidney disease, and genetic targeting of selected MMPs and ADAMs in different mouse models of kidney disease showed that they can have detrimental and protective roles. In particular, MMP-2, MMP-7, MMP-9, ADAM10 and ADAM17 have been shown to have a mainly profibrotic effect and might therefore represent therapeutic targets. Each of these proteases has been associated with a different profibrotic pathway that involves tissue remodelling, Wnt-β-catenin signalling, stem cell factor-c-kit signalling, IL-6 trans-signalling or epidermal growth factor receptor (EGFR) signalling. Broad-spectrum metalloproteinase inhibitors have been used to treat fibrotic kidney diseases experimentally but more targeted approaches have since been developed, including inhibitory antibodies, to avoid the toxic side effects initially observed with broad-spectrum inhibitors. These advances not only provide a solid foundation for additional preclinical studies but also encourage further translation into clinical research.

mir-126-5p Promotes Cisplatin Sensitivity of Non-Small-Cell Lung Cancer by Inhibiting ADAM9

OBJECTIVE

The aim of the study was to investigate molecular mechanisms underlying the role of miR-126-5p in cisplatin (DDP) sensitivity of non-small-cell lung cancer (NSCLC).

METHODS

The expression of miR-126-5p and ADAM9 in NSCLC cancer tissues and adjacent tissues, cisplatin-sensitive and drug-resistant NSCLC patient tissues, human normal lung epithelial cells (BESA-2B), human lung adenocarcinoma cell lines A549 and H1560, and cisplatin-resistant mutant cell lines A549/DDP and H1560/DDP was detected by qRT-PCR. After overexpression of miR-126-5p or ADAM9 in A549/DDP and H1560/DDP, MTT and clone formation were used to detect the cell proliferation ability of each treatment group. Flow cytometry was used to detect changes in cell apoptosis. The protein expression of ADAM9 and key molecules of PTEN/PI3K/Akt pathways in cells was measured by western blot.

RESULTS

Compared with NSCLC adjacent tissues and NSCLC cisplatin-sensitive tissues, miR-126-5p expression was downregulated in NSCLC tissues and cisplatin-resistant NSCLC tissues and ADAM9 was upregulated. qRT-PCR further detected that miR-126-5p was downregulated in A549, H1560, and their cisplatin-resistant strains A549/DDP and H1560/DDP, while ADAM9 was upregulated. Moreover, overexpression of miR-126-5p inhibited A549/DDP and H1560/DDP cell proliferation and promoted cell apoptosis. The results of dual luciferase showed that miR-126-5p targeted and negatively regulated ADAM9. We also found that overexpression of ADAM9 could reverse the effects of miR-126-5p on NSCLC cell proliferation, apoptosis, and cisplatin sensitivity, and this effect may be achieved by inhibiting the activity of the PTEN/PI3K/Akt signaling pathway.

CONCLUSION

Our data indicated that miR-126-5p may negatively regulate ADAM9 to promote the sensitivity of clinical DDP treatment of NSCLC and be a potential therapeutic target for NSCLC treatment.

ADAM9 enhances Th17 cell differentiation and autoimmunity by activating TGF-β1

The a disintegrin and metalloproteinase (ADAM) family of proteinases alter the extracellular environment and are involved in the development of T cells and autoimmunity. The role of ADAM family members in Th17 cell differentiation is unknown. We identified ADAM9 to be specifically expressed and to promote Th17 differentiation. Mechanistically, we found that ADAM9 cleaved the latency-associated peptide to produce bioactive transforming growth factor β1, which promoted SMAD2/3 phosphorylation and activation. A transcription factor inducible cAMP early repressor was found to bind directly to the ADAM9 promoter and to promote its transcription. Adam9-deficient mice displayed mitigated experimental autoimmune encephalomyelitis, and transfer of Adam9-deficient myelin oligodendrocyte globulin-specific T cells into Rag1 ^-/- mice failed to induce disease. At the translational level, an increased abundance of ADAM9 levels was observed in CD4⁺ T cells from patients with systemic lupus erythematosus, and ADAM9 gene deletion in lupus primary CD4⁺ T cells clearly attenuated their ability to differentiate into Th17 cells. These findings revealed that ADAM9 as a proteinase provides Th17 cells with an ability to activate transforming growth factor β1 and accelerates its differentiation, resulting in aberrant autoimmunity.

Involvement of the A disintegrin and metalloproteinase 9 in oral cancer cell invasion

The aims of this study were to determine the functional roles of the transmembrane glycoprotein, Disintegrin and metalloproteinase domain-containing protein 9 (ADAM 9), in the phosphorylation of epidermal growth factor receptor (EGFR) and AKT and in the aggressiveness of oral cancer cells. Immunohistochemistry and immunoblotting were conducted to determine expression of ADAM 9 and the levels of EGFR phosphorylated at the tyrosine 1173 residue (p-EGFR^tyr1173 ) and AKT phosphorylated at the serine 473 residue (p-AKT^ser473 ) in oral cancer tissues and in the oral cancer cell lines HN5, HN6, HN15, and HN008. Small interfering RNA (siRNA) was used to inhibit expression of ADAM9 mRNA, and thus production of ADAM9 protein, in oral cancer cells. ADAM9-knockdown cells were examined for p-EGFR^tyr1173 and p-AKT^ser473 levels and used for cell proliferation and invasion assays. A positive correlation among overexpression of ADAM 9, p-EGFR^tyr1173 , and p-AKT^ser473 was found in oral cancer tissues. These biomolecules were also overexpressed in HN6 and HN15 cell lines. Expression of ADAM9 in HN6 and HN15 cells was statistically significantly inhibited by siRNA against ADAM9 mRNA (siADAM9) compared with the negative-control siRNA (scramble). The levels of p-AKT^ser473 , but not those of p-EGFR^tyr1173 , were statistically significantly blocked by siADAM9. Although the proliferation rates of ADAM9 knocked-down HN6 and HN15 cells did not differ from those of cells exposed to scramble, a statistically significant decrease in cell invasion was found in these ADAM9-silenced cells. These results suggest a functional role of the ADAM 9/AKT signaling pathway in oral cancer cell invasion, which may be beneficial as a therapeutic target of oral cancer.

Structure, regulatory factors and cancer-related physiological effects of ADAM9

The ADAMs family belongs to the transmembrane protein superfamily of zinc-dependent metalloproteases, which consists of multiple domains. These domains have independent but complementary functions that enable them to participate in multiple biological processes. Among them, ADAM9 can not only participate in the degradation of extracellular matrix as a metalloprotease, but also mediate tumor cell adhesion through its deintegrin domain, which is closely related to tumor invasion and metastasis. It is widely expressed in a variety of tumor cells and can affect the proliferation, invasion and metastasis of related cancer cells. We provide our views on current progress, its increasing importance as a strategic treatment goal, and our vision for the future of ADAM9.

Leukotriene receptor antagonists enhance HCC treatment efficacy by inhibiting ADAMs and suppressing MICA shedding

In our previous genome-wide association study, we demonstrated the association between MHC class I-related chain A (MICA) and hepatocellular carcinoma (HCC) development in patients with chronic hepatitis C. Increasing membrane-bound MICA (mMICA) in cancer cells by reducing MICA sheddases facilitates natural killer (NK) cell-mediated cytotoxicity. Our recent study clarified that A disintegrin and metalloproteases (ADAM), including ADAM9, are MICA sheddases in HCC, and that the suppression of ADAMs increases mMICA, demonstrating the rationality of mMICA-NK targeted therapy. Furthermore, we showed that regorafenib suppresses ADAM9 transcriptionally and translationally. A library of FDA-approved drugs was screened for more efficient inhibitors of ADAM9. Flow cytometry evaluation of the expression of mMICA after treatment with various candidate drugs identified leukotriene receptor antagonists as potential ADAM9 inhibitors. Furthermore, leukotriene receptor antagonists alone or in combination with regorafenib upregulated mMICA, which was in turn downregulated by leukotriene C4 and D4 via ADAM9 function. Our study demonstrates that leukotriene receptor antagonists could be developed as novel drugs for immunological control and suppression of ADAM9 in HCC. Further, leukotriene receptor antagonists should be explored as combination therapy partners with conventional multi-kinase inhibitors for developing therapeutic strategies with enhanced efficacies for HCC management and treatment.

ADAM9 Mediates Triple-Negative Breast Cancer Progression via AKT/NF-κB Pathway

Upregulation of a disintegrin and metalloprotease 9 (ADAM9) is correlated with progression of cancers, such as prostate, bladder, and pancreatic cancers. However, its role in triple-negative breast cancer (TNBC) is still unclear. Our study aimed to investigate whether ADAM9 is upregulated and promoted the aggressiveness in TNBC. Breast cancer cell lines and patient specimens were used to evaluate the ADAM9 expression by western blotting and immunohistochemistry staining, respectively. Compared with the non-TNBC, ADAM9 expression was significantly increased in TNBC cells and TNBC patient specimens. Based on the data acquired from public databases, the correlation between ADAM9 expression and breast cancer patient survival was analyzed by Kaplan-Meier method. It was shown that ADAM9 overexpression was significantly correlated with poorer survival in patients with TNBC. Furthermore, ADAM9 in TNBC cells was knocked down by small interference RNA and then studied by the MTT/colony formation assay, wound healing assay and transwell invasion assay on the cell proliferation, migration, and invasion, respectively. We found that inhibiting ADAM9 expression suppressed TNBC cell proliferation, migration, and invasion by lowering the activation of AKT/NF-κB pathway. Our results demonstrated that ADAM9 is an important molecule in mediating TNBC aggressiveness and may be a potential useful therapeutic target in TNBC treatment.

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.

Fisetin Suppresses the Proliferation and Metastasis of Renal Cell Carcinoma through Upregulation of MEK/ERK-Targeting CTSS and ADAM9

Fisetin, a natural flavonoid, is known to have anticarcinogenic effects against several cancers, but its role in mediating renal cell carcinoma (RCC) progression has not been delineated. Cell viability, cytotoxicity, and cell cycle distribution were measured using the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and propidium iodide staining with flow cytometry. The in vitro migration and invasion assay was used to examine in vivo cell migration and invasion. Human protease antibody array analysis was conducted with cell migration/invasion-related proteins. Western blotting and quantitative reverse transcription polymerase chain reaction were used for assessing protein expression related to the cell cycle, cell invasion, and mitogen-activated protein kinase (MAPK) signaling pathway. We found that fisetin significantly inhibited cell viability through cell cycle arrest in the G2/M phase, in addition to downregulating cyclin D1 and upregulating p21/p27. Fisetin inhibited the migration and invasion of human RCC cells through the downregulation of CTSS and a disintegrin and metalloproteinase 9 (ADAM9). Fisetin also upregulated ERK phosphorylation in 786-O and Caki-1 cells. Furthermore, treatment with a MEK inhibitor (UO126) reduced the inhibitory effects of fisetin on the metastasis of RCC cells through the ERK/CTSS/ADAM9 pathway. Fisetin inhibits proliferation and metastasis of RCC cells by downregulating CTSS and ADAM9 through the MEK/ERK signaling pathway. These findings indicate that fisetin is a promising antitumor agent against RCC.

ADAM9 Expression in Uterine Cervical Cancer and Its Associated Factors

Background:

Cervical cancer is a preventable disease caused by human papillomaviruses. It is the third most common cancer to occur in women of reproductive age. The ADAM9 protein plays a role in basement membrane degradation and tumour metastasis in certain types of tumour. Thus, it has the potential to become a new targeted therapy. The objective of this study was to investigate ADAM9 expression in cervical cancer and to determine the factors associated with ADAM9-positive expression.

Methods:

This cross-sectional study was conducted in Hospital Universiti Sains Malaysia (HUSM) Kelantan, Malaysia from December 2010 to December 2012. Histological slides obtained from 95 cervical cancer cases diagnosed and/or treated in HUSM from 2000 to 2010 were analysed. The ADAM9 immunostain was then performed on the paraffin blocks. The statistical data entry and analysis were done using SPSS version 18.0. Multiple logistic regression analysis was performed to determine the factors associated with ADAM9-positive expression.

Result:

Of the 95 cervical cancer patients included in the study, 72 (75.8%) patients showed positive ADAM9 expression. The mean age of the patients was 53.89 (10.83) years old. Squamous cell carcinoma was the most common type of cervical cancer (n = 67, 70.5%). Factors that showed a statistically significant association with ADAM9-positive expression were tumour size (adjusted odds ratio [adj. OR]: 1.08; 95% confidence interval [CI]: 1.02, 1.13; p = 0.004), distant metastasis (adj. OR: 12.82; 95% CI: 1.91, 86.13; p = 0.009) and the histological type of cervical cancer (i.e. squamous cell carcinoma) (adj. OR: 7.39; 95% CI: 1.42, 38.51; p = 0.017).

Conclusion:

The ADAM9 immunostain was consistently positive in malignant cells. Thus, ADAM9 expression can be used as a prognostic/therapeutic indicator in aiding clinician decision-making regarding patient treatment (targeted therapy).

MicroRNA-30a suppresses the proliferation, migration and invasion of human renal cell carcinoma cells by directly targeting ADAM9

An increasing number of studies reported that microRNA (miR)-30a was dysregulated in several types of human cancer and may contribute to cancer carcinogenesis and progression. However, its expression and roles in renal cell carcinoma (RCC) remain unknown. In the present study, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to quantify miR-30a expression in RCC tissues and cell lines. The cell counting kit-8 assay, migration and invasion assays were used to evaluate the roles of miR-30a on the proliferation, migration and invasion of RCC cells. The target gene of miR-30a was identified by luciferase reporter assays, RT-qPCR and western blotting. The results indicated that miR-30a was downregulated in RCC tissues and cell lines compared with corresponding noncancerous tissues and normal renal cell line, respectively. Re-expression of miR-30a inhibited the proliferation, migration and invasion of RCC cells. Additionally, ADAM metallopeptidase domain 9 (ADAM9) was validated as a direct target of miR-30a. Furthermore, the knockdown of ADAM9 by small interfering RNAs was able to mimic the effects of miR-30a overexpression in RCC cells. These results highlight the important role for miR-30a in the occurrence and development of RCC, and the restoration of miR-30a might be investigated as a potential strategy for treating RCC.

The pleiotropic roles of ADAM9 in the biology of solid tumors

A disintegrin and a metalloprotease (ADAM) 9 is a metzincin cell-surface protease involved in several biological processes such as myogenesis, fertilization, cell migration, inflammatory response, proliferation, and cell-cell interactions. ADAM9 has been found over-expressed in several solid tumors entities such as glioma, melanoma, prostate cancer, pancreatic ductal adenocarcinoma, gastric, breast, lung, and liver cancers. Immunohistochemical analyses highlight ADAM9 expression by actual cancer cells and associate its abundant presence with clinicopathological features such as shortened overall survival, poor tumor grade, de-differentiation, therapy resistance, and metastasis formation. In each of these tumors, ADAM9 may contribute to tumor biology via proteolytic or non-proteolytic mechanisms. For example, in liver cancer, ADAM9 has been found to shed MHC class I polypeptide-related sequence A, contributing towards the evasion of tumor immunity. ADAM9 may also contribute to tumor biology in non-proteolytic ways probably through interaction with different integrins. For example, in melanoma, the interaction between ADAM9 and β1 integrins facilitates tumor stroma cross talks, which then promotes invasion and metastasis via the activation of MMP1 and MMP2. In breast cancer, the interaction between β1 integrins on endothelial cells and ADAM9 on tumor cells facilitate tumor cell extravasation and invasion to distant sites. This review summarizes the present knowledge on ADAM9 in solid cancers, and the different mechanisms which it employ to drive tumor progression.

Sorting nexin 9 (SNX9) regulates levels of the transmembrane ADAM9 at the cell surface

ADAM9 is an active member of the family of transmembrane ADAMs (a disintegrin and metalloproteases). It plays a role in processes such as bone formation and retinal neovascularization, and importantly, its expression in human cancers correlates with disease stage and poor prognosis. Functionally, ADAM9 can cleave several transmembrane proteins, thereby shedding their ectodomains from the cell surface. Moreover, ADAM9 regulates cell behavior by binding cell-surface receptors such as integrin and membrane-type matrix metalloproteases. Because these functions are mainly restricted to the cell surface, understanding the mechanisms regulating ADAM9 localization and activity at this site is highly important. To this end, we here investigated how intracellular trafficking regulates ADAM9 availability at the cell surface. We found that ADAM9 undergoes constitutive clathrin-dependent internalization and subsequent degradation or recycling to the plasma membrane. We confirmed previous findings of an interaction between ADAM9 and the intracellular sorting protein, sorting nexin 9 (SNX9), as well as its close homolog SNX18. Knockdown of either SNX9 or SNX18 had no apparent effects on ADAM9 internalization or recycling. However, double knockdown of SNX9 and SNX18 decreased ADAM9 internalization significantly, demonstrating a redundant role in this process. Moreover, SNX9 knockdown revealed a nonredundant effect on overall ADAM9 protein levels, resulting in increased ADAM9 levels at the cell surface, and a corresponding increase in the shedding of Ephrin receptor B4, a well-known ADAM9 substrate. Together, our findings demonstrate that intracellular SNX9-mediated trafficking constitutes an important ADAM9 regulatory pathway.

ADAM9 is over-expressed in human ovarian clear cell carcinomas and suppresses cisplatin-induced cell death

ADAMs (a disintegrin and metalloproteinases) are involved in various biological events such as cell adhesion, migration and invasion, membrane protein shedding and proteolysis. However, there have been no systematic studies on the expression of ADAMs in human ovarian carcinomas. We therefore examined mRNA expression of all the proteolytic ADAM species including ADAM8, 9, 10, 12, 15, 17, 19, 20, 21, 28, 30, 33 and ADAMDEC1 in human ovarian carcinomas, and found that prototype membrane-anchored ADAM9m, but not secreted isoform ADAM9s, is significantly over-expressed in carcinomas than in control non-neoplastic ovarian tissue. Among the histological subtypes of serous, endometrioid, mucinous and clear cell carcinomas, ADAM9m expression was highest in clear cell carcinomas. Immunohistochemistry showed that all the clear cell carcinoma samples displayed ADAM9m primarily on the carcinoma cell membrane. By immunoblotting, ADAM9m was detected mainly in an active form in the clear cell carcinoma tissues. When two clear cell carcinoma cell lines (RMG-I and TOV21G cells) with ADAM9m expression were treated with cisplatin, viability was significantly reduced and apoptosis increased in ADAM9m knockdown cells compared with mock transfectants. In addition, treatment of the cells with neutralizing anti-ADAM9m antibody significantly decreased viability compared with non-immune IgG, whereas ADAM9m over-expression significantly increased viability compared with mock transfectants. Our data show, to the best of our knowledge, for the first time, that ADAM9m is over-expressed in an activated form in human ovarian clear cell carcinomas, and suggest that ADAM9m plays a key role in cisplatin resistance.

Loss of ADAM9 expression impairs β1 integrin endocytosis, focal adhesion formation and cancer cell migration

The transmembrane protease ADAM9 is frequently upregulated in human cancers, and it promotes tumour progression in mice. In vitro, ADAM9 regulates cancer cell adhesion and migration by interacting with integrins. However, how ADAM9 modulates integrin functions is not known. We here show that ADAM9 knockdown increases β1 integrin levels through mechanisms that are independent of its protease activity. In ADAM9-silenced cells, adhesion to collagen and fibronectin is reduced, suggesting an altered function of the accumulated integrins. Mechanistically, ADAM9 co-immunoprecipitates with β1 integrin, and both internalization and subsequent degradation of β1 integrin are significantly decreased in ADAM9-silenced cells, with no effect on β1 integrin recycling. Accordingly, the formation of focal adhesions and actin stress fibres in ADAM9-silenced cells is altered, possibly explaining the reduction in cell adhesion and migration in these cells. Taken together, our data provide mechanistic insight into the ADAM9-integrin interaction, demonstrating that ADAM9 regulates β1 integrin endocytosis. Moreover, our findings indicate that the reduced migration of ADAM9-silenced cells is, at least in part, caused by the accumulation and altered activity of β1 integrin at the cell surface.

Overexpression of ADAM9 in oral squamous cell carcinoma

Overexpression of a disintegrin and metalloproteinase 9 (ADAM9) has been shown in various types of cancer. Some studies have reported inconclusive findings regarding chromosomal aberrations in the ADAM9-containing region and ADAM9 expression in oral cancer. Therefore, in this study, ADAM9 protein expression was determined and compared between oral squamous cell carcinoma (OSCC) and normal oral tissues, and between oral cancer cell lines and human oral keratinocytes (HOKs). In total, 34 OSCC and 10 healthy paraffin-embedded tissue sections were probed with an anti-ADAM9 antibody, and the immunohistochemical score was determined by multiplying the percentage of positively stained cells with the intensity score. Four different oral cancer and eight independent HOK cell lines were cultured, and the expression of membrane ADAM9 and active ADAM9 at 84 kDa in these cell lines was assayed by flow cytometry and western blot hybridization, respectively. The results showed that the median immunohistochemical score of ADAM9 expression in OSCC tissues was significantly greater than that in normal tissues (P<0.001). Furthermore, among OSCC cases, intense staining of ADAM9 expression was detected in well-differentiated and in moderately-differentiated OSCC; ADAM9 expression was also correlated with an increased degree of cell differentiation (r=0.557; P=0.001). Expression of membrane ADAM9 was present in 3/4 cancer cell lines. Expression of active ADAM9 varied among all the tested cell lines, but significantly higher ADAM9 expression was present in certain cancer cell lines than those in HOKs (P<0.05). In summary, ADAM9 expression is enhanced in OSCC and oral cancer cell lines, suggesting its role in the pathogenesis of oral cancer. Similar to the overexpression of ADAM9 in well-differentiated prostate cancer, high degrees of ADAM9 expression have also been observed in well-differentiated OSCC.

MicroRNA-154/ADAM9 axis inhibits the proliferation, migration and invasion of breast cancer cells

Breast cancer is the leading cause for cancer-associated mortality in women. Although great progress has been made in the earlier diagnosis and systemic therapy of patients with breast cancer in recent years, recurrence or distant metastasis continue to present major barriers to the successful treatment of breast cancer. Therefore, fully understanding the molecular mechanisms underlying the progression of breast cancer may be critical for the development of effective therapeutic strategies against breast cancer. The aim of the present study was to explore the expression, function and molecular mechanisms of microRNA-154 (miR-154) in human breast cancer. It was demonstrated that miR-154 was significantly downregulated in breast cancer tissue and cell lines. The restoration of miR-154 expression suppressed the proliferation, migration and invasion of breast cancer cells. ADAM metallopeptidase domain 9 (ADAM9) was identified as a novel direct target for miR-154 in breast cancer. It was demonstrated that miR-154 acted as a tumor suppressor in breast cancer by targeting ADAM9. The results of the present study suggest that the restoration of miR-154 expression may be an effective therapeutic strategy for the treatment of breast cancer in the future.

MicroRNA‑543 inhibits proliferation, invasion and induces apoptosis of glioblastoma cells by directly targeting ADAM9

Glioma is the most common type of malignant brain tumor in humans and accounts for 81% of all malignant brain tumor cases in adults. The abnormal expression of microRNAs (miRs) has been reported to be important in the formation and progression of various types of human cancer, including glioblastoma (GBM). Therefore, studies into the expression, and roles of microRNAs as diagnostic and prognostic markers, as well as their therapeutic value for patients with GBM are warranted. The expression and roles of miR‑543 have been reported in several types of human cancer. However, the role of miR‑543 in GBM remains unclear. In the current study, the expression pattern of miR‑543 in GBM, the effects of miR‑543 on GBM cells and the underlying molecular mechanism was determined. The results of the present study demonstrated that miR‑543 was significantly downregulated in GBM tissue samples and cell lines. Furthermore, the upregulation of miR‑543 inhibited GBM cell proliferation and invasion, as well as promoted cell apoptosis. In addition, a disintegrin and metalloproteinase 9 (ADAM9) was identified to be a direct target gene of miR‑543. Furthermore, ADAM9 was significantly upregulated in GBM tissue samples and its expression was inversely correlated with miR‑543 expression in GBM tissue, suggesting that miR‑543 downregulation may contribute to ADAM9 upregulation in GBM. Finally, the results of the rescue experiment indicated that ADAM9 overexpression significantly reversed the effects of miR‑543 on the proliferation, invasion and apoptosis of GBM cells, suggesting that miR‑543 serves as a tumor suppressor in GBM through ADAM9 regulation. Overall, these findings indicate that the miR‑543/ADAM9 signaling pathway may provide as a potential therapeutic strategy for GBM.

Loss of tumor suppressor miR-126 contributes to the development of hepatitis B virus-related hepatocellular carcinoma metastasis through the upregulation of ADAM9

Hepatocellular carcinoma is the most common histological type of primary liver cancer, which represents the second leading cause of cancer-related mortality. MiR-126 was reported to be downregulated in hepatocellular carcinoma tissues, compared with its levels in noncancerous tissues. However, baseline miR-126 expression levels in hepatitis B virus-related hepatocellular carcinoma patients who did not undergo pre-operational treatment remains unknown since hepatitis B virus infection and pre-operational transcatheter arterial chemoembolization were shown to upregulate miR-126 expression. Here, we demonstrated that miR-126 is generally downregulated in a homogeneous population of pre-operational treatment-naïve hepatitis B virus-related hepatocellular carcinoma patients (84.0%, 84/100), and its expression is significantly associated with pre-operational alpha-fetoprotein levels ( p < 0.05), microvascular invasion ( p < 0.05), tumor metastasis ( p < 0.05), as well as early recurrence (12 months after surgery; p < 0.01). Furthermore, the results of our study revealed that miR-126 is negatively correlated with ADAM9 expression in hepatitis B virus-related hepatocellular carcinoma patients. Overexpression of miR-126 was shown to attenuate ADAM9 expression in hepatocellular carcinoma cells, which subsequently inhibits cell migration and invasion in vitro. In addition, Cox proportional hazards regression model analysis showed that ADAM9 levels, tumor number, microvascular invasion, and tumor metastasis rate represent independent prognostic factors for shorter recurrence-free survival. In conclusion, we demonstrated that the loss of tumor suppressor miR-126 in hepatitis B virus-related hepatocellular carcinoma cells contributes to the development of metastases through the upregulated expression of its target gene, ADAM9. MiR-126-ADAM9 pathway-based therapeutic targeting may represent a novel approach for the inhibition of hepatitis B virus-related hepatocellular carcinoma metastases.

Deletion of ADAM-9 in HGF/CDK4 mice impairs melanoma development and metastasis

ADAM-9 is a metalloproteinase expressed in peritumoral areas by invading melanoma cells and by adjacent peritumoral stromal cells; however, its function in stromal and melanoma cells is not fully understood. To address this question in vivo in a spontaneous melanoma model, we deleted ADAM-9 in mice carrying the hepatocyte growth factor (Hgf) transgene and knock-in mutation Cdk4^R24C/R24C, demonstrated to spontaneously develop melanoma. Spontaneous melanoma arose less frequently in ADAM-9-deleted mice than in controls. Similarly reduced tumor numbers (although with faster growth kinetics) were detected upon induction of melanoma with 7,12-dimethylbenz[a]anthracene (DMBA). However, more lesions were induced at early time points in the absence of ADAM-9. Increased initial and decreased late tumor numbers were paralleled by altered tumor cell proliferation, but not apoptosis or inflammation. Importantly, significantly reduced lung metastases were detected upon ADAM-9 deletion. Using in vitro assays to address this effect mechanistically, we detected reduced adhesion and transmigration of ADAM-9-silenced melanoma cells to/through the endothelium. This implies that ADAM-9 functionally and cell autonomously mediates extravasation of melanoma cells. In vitro and in vivo we demonstrated that the basement membrane (BM) component laminin β3-chain is a direct substrate of ADAM-9, thus contributing to destabilization and disruption of the BM barrier during invasion. In in vitro invasion assays using human melanoma cells and skin equivalents, depletion of ADAM-9 resulted in decreased invasion of the BM, which remained almost completely intact, as shown by continuous staining for laminin β3-chain. Importantly, supplying soluble ADAM-9 to the system reversed this effect. Taken together, our data show that melanoma derived ADAM-9 autonomously contributes to melanoma progression by modulating cell adhesion to the endothelium and altering BM integrity by proteolytically processing the laminin-β3 chain. This newly described process and ADAM-9 itself may represent potential targets for anti-tumor therapies.

Characterization of the catalytic properties of the membrane-anchored metalloproteinase ADAM9 in cell-based assays

ADAM9 (A Disintegrin And Metalloprotease 9) is a membrane-anchored metalloproteinase that has been implicated in pathological retinal neovascularization and in tumor progression. ADAM9 has constitutive catalytic activity in both biochemical and cell-based assays and can cleave several membrane proteins, including epidermal growth factor and Ephrin receptor B4; yet little is currently known about the catalytic properties of ADAM9 and its post-translational regulation and inhibitor profile in cell-based assays. To address this question, we monitored processing of the membrane-anchored Ephrin receptor B4 (EphB4) by co-expressing ADAM9, with the catalytically inactive ADAM9 E > A mutant serving as a negative control. We found that ADAM9-dependent shedding of EphB4 was not stimulated by three commonly employed activators of ADAM-dependent ectodomain shedding: phorbol esters, pervanadate or calcium ionophores. With respect to the inhibitor profile, we found that ADAM9 was inhibited by the hydroxamate-based metalloprotease inhibitors marimastat, TAPI-2, BB94, GM6001 and GW280264X, and by 10 nM of the tissue inhibitor of metalloproteinases (TIMP)-3, but not by up to 20 nM of TIMP-1 or -2. Additionally, we screened a non-hydroxamate small-molecule library for novel ADAM9 inhibitors and identified four compounds that selectively inhibited ADAM9-dependent proteolysis over ADAM10- or ADAM17-dependent processing. Taken together, the present study provides new information about the molecular fingerprint of ADAM9 in cell-based assays by showing that it is not stimulated by strong activators of ectodomain shedding and by defining a characteristic inhibitor profile. The identification of novel non-hydroxamate inhibitors of ADAM9 could provide the basis for designing more selective compounds that block the contribution of ADAM9 to pathological neovascularization and cancer.

MicroRNA-140 represses glioma growth and metastasis by directly targeting ADAM9

Glioma is the most frequent primary malignant tumor of the human brain. Recently, great progress has been made in the combined therapy of glioma. However, the clinical effects of these treatments and prognosis for patients with glioma remains poor. MicroRNAs (miRNAs) have been demonstrated to play important roles in the initiation and progression of various types of human cancers, also including glioma. The present study investigated the expression patterns of microRNA‑140 (miR-140) in glioma, and the roles of miR-140 in glioma cell proliferation, migration and invasion. The results showed that miR-140 was significantly downreuglated in glioma tissues and cell lines, and low expression levels of miR-140 were correlated with World Health Organization (WHO) grade and Karnofsky performance score (KPS) of glioma patients. Restoration of miR-140 obviously suppressed glioma cell proliferation, migration and invasion. In addition, a disintegrin and metalloproteinase 9 (ADAM9) was identified as a novel direct target gene of miR-140 in glioma. Furthermore, knockdown of ADAM9 simulated the tumor suppressor functions of miR-140, while overexpression of ADAM9 abrogated these suppressive effects induced by miR-140 in glioma cells. In conclusion, the present study demonstrated the expression and clinical roles of miR-140 in glioma and suggested that miR-140 inhibited proliferation, migration and invasion of glioma cells, partially at least via suppressing ADAM9 expression. Therefore, miR-140 may be a novel candidate target for the development of therapeutic strategies for patients with glioma.

Changes in expressions of ADAM9, 10, and 17 as well as α-secretase activity in renal cell carcinoma

BACKGROUND

ADAM9, 10, and 17 are a class of disintegrins and metallproteinases with α-secretase activity. There are conflicting results regarding the role(s) of ADAM9, 10, and 17 in carcinogenesis, and only a few studies have examined their levels and cellular localization in renal cell carcinoma (RCC). Studies examining changes in α-secretase activity in RCC compared to enzymatic activity of the uninvolved kidney are lacking.

METHOD

A cross-sectional study was conducted in 56 patients undergoing radical nephrectomy after the diagnosis of RCC. α-Secretase activity was determined using flourogenic substrate in freshly frozen tumor tissues as well as similarly treated tissues from the neighboring kidney. Immunohistochemical analyses of ADAM9, 10, and 17 were also performed.

RESULTS

α-Secretase activity decreased markedly in all types of RCC as compared to neighboring uninvolved kidney tissue having 5 to 10 times higher levels of α-secretase activity. Although type-dependent variations were observed, tumoral expressions of ADAMs, except for ADAM17, were lower in the tumors compared to that of neighboring tissues, but the changes in α-secretase activity were greater. In RCC tissue, ADAM9 expressions were localized in nuclear and cytoplasmic compartments, whereas ADAM10 and 17 were present predominately in the cytoplasm potentially explaining the markedly decreased enzyme activity. Membranous localization of ADAMs was noted in uninvolved kidney tissue.

CONCLUSIONS

The loss of α-secretase activity observed here in conjunction with previous findings argue against tumorigenic effects of ADAM9, 10, and 17 supporting that increased nuclear and cytoplasmic expression may be an attempt to compensate for loss of function.

Platelet integrin 61 controls lung metastasis through direct binding to cancer cell-derived ADAM9

Metastatic dissemination of cancer cells, which accounts for 90% of cancer mortality, is the ultimate hallmark of malignancy. Growing evidence suggests that blood platelets have a predominant role in tumor metastasis; however, the molecular mechanisms involved remain elusive. Here, we demonstrate that genetic deficiency of integrin α6β1 on platelets markedly decreases experimental and spontaneous lung metastasis. In vitro and in vivo assays reveal that human and mouse platelet α6β1 supports platelet adhesion to various types of cancer cells. Using a knockdown approach, we identified ADAM9 as the major counter receptor of α6β1 on both human and mouse tumor cells. Static and flow-based adhesion assays of platelets binding to DC-9, a recombinant protein covering the disintegrin-cysteine domain of ADAM9, demonstrated that this receptor directly binds to platelet α6β1. In vivo studies showed that the interplay between platelet α6β1 and tumor cell-expressed ADAM9 promotes efficient lung metastasis. The integrin α6β1-dependent platelet-tumor cell interaction induces platelet activation and favors the extravasation process of tumor cells. Finally, we demonstrate that a pharmacological approach targeting α6β1 efficiently impairs tumor metastasis through a platelet-dependent mechanism. Our study reveals a mechanism by which platelets promote tumor metastasis and suggests that integrin α6β1 represents a promising target for antimetastatic therapies.

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.

miR-126-3p Inhibits Thyroid Cancer Cell Growth and Metastasis, and Is Associated with Aggressive Thyroid Cancer

BACKGROUND

Previous studies have shown that microRNAs are dysregulated in thyroid cancer and play important roles in the post-transcriptional regulation of target oncogenes and/or tumor suppressor genes.

METHODOLOGY/PRINCIPAL FINDINGS

We studied the function of miR-126-3p in thyroid cancer cells, and as a marker of disease aggressiveness. We found that miR-126-3p expression was significantly lower in larger tumors, in tumor samples with extrathyroidal invasion, and in higher risk group thyroid cancer in 496 papillary thyroid cancer samples from The Cancer Genome Atlas study cohort. In an independent sample set, lower miR-126-3p expression was observed in follicular thyroid cancers (which have capsular and angioinvasion) as compared to follicular adenomas. Mechanistically, ectopic overexpression of miR-126-3p significantly inhibited thyroid cancer cell proliferation, in vitro (p<0.01) and in vivo (p<0.01), colony formation (p<0.01), tumor spheroid formation (p<0.05), cellular migration (p<0.05), VEGF secretion and endothelial tube formation, and lung metastasis in vivo. We found 14 predicted target genes, which were significantly altered upon miR-126-3p transfection in thyroid cancer cells, and which are involved in cancer biology. Of these 14 genes, SLC7A5 and ADAM9 were confirmed to be inhibited by miR-126-3p overexpression and to be direct targets of miR-136-3p.

CONCLUSIONS/SIGNIFICANCE

To our knowledge, this is the first study to demonstrate that miR-126-3p has a tumor-suppressive function in thyroid cancer cells, and is associated with aggressive disease phenotype.

RNAi-mediated A disintegrin and metalloproteinase 9 gene silencing inhibits the tumor growth of non-small lung cancer in vitro and in vivo

A disintegrin and metalloproteinase 9 (ADAM9) is a type I transmembrane protein that has been associated with cancer development and metastasis in various types of cancer. However, little is known about its role in non-small cell lung cancer (NSCLC). The aim of the present study was to evaluate whether downregulation of ADAM9 affects cell proliferation, apoptosis, migration and invasion in NSCLC. Thus, a recombinant lentiviral small hairpin RNA expression vector carrying ADAM9 was constructed and infected into the human NSCLC cell line A549. Cell proliferation, apoptosis, migration and invasion in vitro and tumor growth in vivo were determined following downregulation of ADAM9 by RNA interference-mediated ADAM9 gene silencing. It was found that downregulation of ADAM9 expression using an RNA silencing approach in A549 tumor cells significantly inhibited cell proliferation, migration and invasion, induced cell apoptosis in vitro, as well as suppressed in vivo tumor growth in an experimental mouse model of lung metastasis. These data indicate that ADAM9 is potentially an important new therapeutic target for the prevention of tumor growth in NSCLC.

ADAM9 disintegrin domain activates human neutrophils through an autocrine circuit involving integrins and CXCR2

ADAM9 is a member of the ADAM family whose expression positively correlates with tumor progression. Besides the metalloprotease activity, ADAM9D interacts with different integrins, modulating cell-adhesion events. Previous studies pointed to an important role for neutrophils in tumor development, as the inhibition of neutrophil migration or depletion of this immune cell impairs tumor growth. However, our understanding of the molecular mechanisms involved in this process, as well as the main key players acting on neutrophils, is very limited. Here, we investigated the possible modulatory effects of ADAM9D on human neutrophil functions. Our results show that ADAM9D promotes neutrophil activation and chemotaxis in a process that depends on the engagement of α_vβ₃ and α₉β₁ integrins and on the activation of PI3K/Akt and MAPK signaling pathway. ADAM9D impairs migration of neutrophils toward fMLP, LTB₄, and IL-8 as classic chemoattractants. This effect is blocked by PTX, a G(i)PCR inhibitor. Furthermore, CXCR2 antagonists RPTX and SB225002 also impaired neutrophil chemotaxis in response to ADAM9D, suggesting a hierarchical cross-talk of integrins with CXCR2. Our results indicate that ADAM9D activates neutrophil functions and may be implicated in the inflammatory events associated with cancer and other disorders.

A disintegrin and metalloproteinase 9 is involved in ectodomain shedding of receptor-binding cancer antigen expressed on SiSo cells

In several human malignancies, the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is associated with aggressive characteristics and poor overall survival. RCAS1 alters the tumor microenvironment by inducing peripheral lymphocyte apoptosis and angiogenesis, while reducing the vimentin-positive cell population. Although proteolytic processing, referred to as "ectodomain shedding," is pivotal for induction of apoptosis by RCAS1, the proteases involved in RCAS1-dependent shedding remain unclear. Here we investigated proteases involved in RCAS1 shedding and the association between tumor protease expression and serum RCAS1 concentration in uterine cancer patients. A disintegrin and metalloproteinase (ADAM) 9 was shown to be involved in the ectodomain shedding of RCAS1. Given the significant correlation between tumor ADAM9 expression and serum RCAS1 concentration in both cervical and endometrial cancer as well as the role for ADAM9 in RCAS1 shedding, further exploration of the regulatory mechanisms by which ADAM9 converts membrane-anchored RCAS1 into its soluble form should aid the development of novel RCAS1-targeting therapeutic strategies to treat human malignancies.

ADAM9 up-regulates N-cadherin via miR-218 suppression in lung adenocarcinoma cells

Lung cancer is the leading cause of cancer death worldwide, and brain metastasis is a major cause of morbidity and mortality in lung cancer. CDH2 (N-cadherin, a mesenchymal marker of the epithelial-mesenchymal transition) and ADAM9 (a type I transmembrane protein) are related to lung cancer brain metastasis; however, it is unclear how they interact to mediate this metastasis. Because microRNAs regulate many biological functions and disease processes (e.g., cancer) by down-regulating their target genes, microRNA microarrays were used to identify ADAM9-regulated miRNAs that target CDH2 in aggressive lung cancer cells. Luciferase assays and western blot analysis showed that CDH2 is a target gene of miR-218. MiR-218 was generated from pri-mir-218-1, which is located in SLIT2, in non-invasive lung adenocarcinoma cells, whereas its expression was inhibited in aggressive lung adenocarcinoma. The down-regulation of ADAM9 up-regulated SLIT2 and miR-218, thus down-regulating CDH2 expression. This study revealed that ADAM9 activates CDH2 through the release of miR-218 inhibition on CDH2 in lung adenocarcinoma.

ADAM9 silencing inhibits breast tumor cell invasion in vitro

ADAM9 (A Disintegrin And Metalloproteinase 9) is a member of the ADAM protein family which contains a disintegrin domain. This protein family plays key roles in many physiological processes, including fertilization, migration, and cell survival. The ADAM proteins have also been implicated in various diseases, including cancer. Specifically, ADAM9 has been suggested to be involved in metastasis. To address this question, we generated ADAM9 knockdown clones of MDA-MB-231 breast tumor cells using silencing RNAs that were tested for cell adhesion, proliferation, migration and invasion assays. In RNAi-mediated ADAM9 silenced MDA-MB-231 cells, the expression of ADAM9 was lower from the third to the sixth day after silencing and inhibited tumor cell invasion in matrigel by approximately 72% when compared to control cells, without affecting cell adhesion, proliferation or migration. In conclusion, the generation of MDA-MB-231 knockdown clones lacking ADAM9 expression inhibited tumor cell invasion in vitro, suggesting that ADAM9 is an important molecule in the processes of invasion and metastasis.

High expression of a disintegrin and metalloproteinase-9 predicts a shortened survival time in completely resected stage I non-small cell lung cancer

The aim of this study was to investigate the abnormal expression of a disintegrin and metalloproteinase-9 (ADAM9) in human resected non-small cell lung cancer (NSCLC) tissue, in order to evaluate the significance of ADAM9 expression in surgically resected NSCLC. Sixty-four cases of completely resected stage I NSCLC with mediastinal N2 lymph node dissection were immunohistochemically analyzed for ADAM9 protein expression. Survival, univariate and multivariate analyses were conducted to assess the significance of ADAM9 expression and its correlation with other clinicopathological characteristics. ADAM9 was observed to be significantly more highly expressed in NSCLC tissue compared with normal control lung tissue (P=0.001). The 5-year survival rate for patients with NSCLC tissues highly expressing ADAM9 was significantly lower when compared with NSCLC tissues of patients exhibiting low expression of ADAM9 (56.9 vs. 88.9%, P= 0.012). Multivariate analysis identified that high expression of ADAM9 is an independent factor of shortened survival time in resected stage I NSCLC (HR, 3.385; 95% CI, 1.224–9.360; P=0.019). These results clearly demonstrate that ADAM9 is highly expressed in NSCLC and highly expressed ADAM9 correlates with shortened survival time, suggesting that ADAM9 is a novel biomarker for predicting prognosis in resected stage I NSCLC. ADAM9 may also become a useful predictive biomarker for the selection of adjuvant chemotherapy treatment of NSCLC.

Stromal fibroblast-specific expression of ADAM-9 modulates proliferation and apoptosis in melanoma cells in vitro and in vivo

ADAMs are members of the zinc metalloproteinase superfamily characterized by the presence of disintegrin and metalloprotease domains. In human melanoma, ADAM-9 is expressed in focalized areas of the tumor-stroma border in both melanoma and stromal cells. However, the role of ADAM-9 in melanoma progression remains elusive. To analyze the role of stromal-derived ADAM-9 for the growth and survival of melanoma cells, we have used in vitro coculture systems of melanoma cells and ADAM-9(-/-) fibroblasts. Coculture of melanoma cells in the presence of ADAM-9(-/-) fibroblasts led to increased melanoma cell proliferation and reduced apoptosis as compared with control cocultures. We identified TIMP-1 and sTNFRI as the two relevant factors expressed in increased amounts in culture supernatants from ADAM-9(-/-) fibroblasts. TIMP-1 was associated with induced melanoma cell proliferation, whereas soluble TNFR1 mediated the reduced cellular apoptosis in vitro. In vivo, injection of murine melanoma cells into the flank of ADAM-9(-/-) animals resulted in the development of significantly larger tumors than in wild-type animals as a result of increased proliferation and decreased apoptosis of melanoma cells. Taken together, stromal expression of ADAM-9 during melanoma development modulates the expression of TIMP-1 and sTNFR1, which in turn affect tumor cell proliferation and apoptosis.

Gene expression profiles of the NCI-60 human tumor cell lines define molecular interaction networks governing cell migration processes

Although there is extensive information on gene expression and molecular interactions in various cell types, integrating those data in a functionally coherent manner remains challenging. This study explores the premise that genes whose expression at the mRNA level is correlated over diverse cell lines are likely to function together in a network of molecular interactions. We previously derived expression-correlated gene clusters from the database of the NCI-60 human tumor cell lines and associated each cluster with function categories of the Gene Ontology (GO) database. From a cluster rich in genes associated with GO categories related to cell migration, we extracted 15 genes that were highly cross-correlated; prominent among them were RRAS, AXL, ADAM9, FN14, and integrin-beta1. We then used those 15 genes as bait to identify other correlated genes in the NCI-60 database. A survey of current literature disclosed, not only that many of the expression-correlated genes engaged in molecular interactions related to migration, invasion, and metastasis, but that highly cross-correlated subsets of those genes engaged in specific cell migration processes. We assembled this information in molecular interaction maps (MIMs) that depict networks governing 3 cell migration processes: degradation of extracellular matrix, production of transient focal complexes at the leading edge of the cell, and retraction of the rear part of the cell. Also depicted are interactions controlling the release and effects of calcium ions, which may regulate migration in a spaciotemporal manner in the cell. The MIMs and associated text comprise a detailed and integrated summary of what is currently known or surmised about the role of the expression cross-correlated genes in molecular networks governing those processes.

Graded activation of the MEK1/MT1-MMP axis determines renal epithelial cell tumor phenotype

Activation of Raf/Ras/mitogen-activated protein kinase (MEK)/mitogen-activated protein kinase signaling and elevated expression of membrane type-1 matrix metalloproteinase (MT1-MMP) are associated with von Hippel-Lindau gene alterations in renal cell carcinoma. We postulated that the degree of MEK activation was related to graded expression of MT1-MMP and the resultant phenotype of renal epithelial tumors. Madin Darby canine kidney epithelial cells transfected with a MEK1 expression plasmid yielded populations with morphologic phenotypes ranging from epithelial, mixed epithelial/mesenchymal to mesenchymal. Clones were analyzed for MEK1 activity, MT1-MMP expression and extent of epithelial-mesenchymal transition. Phenotypes of the MDCK-MEK1 clones were evaluated in vivo with nu/nu mice. Tissue microarray of renal cell cancers was quantitatively assessed for expression of phosphorylated MEK1 and MT1-MMP proteins and correlations drawn to Fuhrman nuclear grade. Graded increases in the MEK signaling module were associated with graded induction of epithelial-mesenchymal transition of the MDCK cells and induction of MT1-MMP transcription and synthesis. Inhibition of MEK1 and MT1-MMP activity reversed the epithelial-mesenchymal transition. Tumors generated by epithelial, mixed epithelial/mesenchymal and mesenchymal MDCK clones demonstrated a gradient of phenotypes extending from well-differentiated, fully encapsulated non-invasive tumors to tumors with an anaplastic morphology, high Fuhrman nuclear score, neoangiogenesis and invasion. Tumor microarray demonstrated a statistically significant association between the extent of phosphorylated MEK1, MT1-MMP expression and nuclear grade. We conclude that graded increases in the MEK1 signaling module are correlated with M1-MMP expression, renal epithelial cell tumor phenotype, invasive activity and nuclear grade. Phosphorylated MEK1 and MT1-MMP may represent novel, and mechanistic, biomarkers for the assessment of renal cell carcinoma.

Cyclin D1 expression in B-cell lymphomas

OBJECTIVE

Cyclin D1, an important component of cell cycle machinery and a protein with known oncogenic potential, is downregulated in normal mature B lymphocytes. Its expression detected in a number of malignancies, including B-cell lymphomas, may be important for oncogenesis.

MATERIALS AND METHODS

In our work, we determined the level of cyclin D1 expression in various B-cell lymphomas (i.e., mantle cell lymphoma, B-cell chronic lymphocytic leukemia, diffuse large B-cell lymphoma, follicular lymphoma, and marginal zone lymphoma) and compared it with normal B cells. For cyclin D1 level evaluation, the real-time quantitative polymerase chain reaction data was normalized. We tested five reference genes for stability on our sample set and using the three most stable ones (YWHAZ, ubiquitin c, and HPRT) obtained rather small intra-group variance for cyclin D1 expression in most lymphomas. This allowed their statistically significant ranking according to cyclin D1 expression level.

RESULTS

Median values of normalized cyclin D1 expression determined by real-time quantitative polymerase chain reaction were 1.32 for mantle cell lymphoma, 0.02 for B-cell chronic lymphocytic leukemia, 0.009 for diffuse large B-cell lymphoma, 0.004 for marginal zone lymphoma, 0.002 for follicular lymphoma compared with 0.0003 for reactive lymphoid tissue, and 0.00004 for sorted B cells of healthy donors.

CONCLUSIONS

Our data demonstrate that mantle cell lymphoma, a lymphoma with t(11;14)(q13;q32) translocation, has the level of cyclin D1 increased by four orders of magnitude, while other B-cell lymphomas without t(11;14)(q13;q32) translocation still have the level of cyclin D1 significantly elevated above that of normal lymphocytes (2 orders for B-cell chronic lymphocytic leukemia and an order for other lymphomas) and suggests more than one method of its upregulation in malignant B cells.