RNAi-mediated ADAM9 gene silencing inhibits metastasis of adenoid cystic carcinoma cells

Mesenchymal stem cell (MSC)-derived exosomes as novel vehicles for delivery of miRNAs in cancer therapy

Mesenchymal stem cells (MSCs) are known as promising sources for cancer therapy and can be utilized as vehicles in cancer gene therapy. MSC-derived exosomes are central mediators in the therapeutic functions of MSCs, known as the novel cell-free alternatives to MSC-based cell therapy. MSC-derived exosomes show advantages including higher safety as well as more stability and convenience for storage, transport and administration compared to MSCs transplant therapy. Unmodified MSC-derived exosomes can promote or inhibit tumors while modified MSC-derived exosomes are involved in the suppression of cancer development and progression via the delivery of several therapeutics molecules including chemotherapeutic drugs, miRNAs, anti-miRNAs, specific siRNAs, and suicide gene mRNAs. In most malignancies, dysregulation of miRNAs not only occurs as a consequence of cancer progression but also is directly involved during tumor initiation and development due to their roles as oncogenes (oncomiRs) or tumor suppressors (TS-miRNAs). MiRNA restoration is usually achieved by overexpression of TS-miRNAs using synthetic miRNA mimics and viral vectors or even downregulation of oncomiRs using anti-miRNAs. Similar to other therapeutic molecules, the efficacy of miRNAs restoration in cancer therapy depends on the effectiveness of the delivery system. In the present review, we first provided an overview of the properties and potentials of MSCs in cancer therapy as well as the application of MSC-derived exosomes in cancer therapy. Finally, we specifically focused on harnessing the MSC-derived exosomes for the aim of miRNA delivery in cancer therapy.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomal MicroRNA-126-3p Inhibits Pancreatic Cancer Development by Targeting ADAM9

Pancreatic cancer is a lethal malignancy with relatively few effective therapies. Recent investigations have highlighted the role of microRNAs (miRNAs) as crucial regulators in various tumor processes including tumor progression. Hence the current study aimed to investigate the role of bone marrow mesenchymal stem cell (BMSC)-derived exosomal microRNA-126-3p (miR-126-3p) in pancreatic cancer. Initially, miRNA candidates and related genes associated with pancreatic cancer were screened. PANC-1 cells were transfected with miR-126-3p or silenced a disintegrin and a metalloproteinase-9 (ADAM9) to examine their regulatory roles in pancreatic cancer cells. Additionally, exosomes derived from BMSCs were isolated and co-cultured with pancreatic cancer cells to elucidate the effects of exosomes in pancreatic cancer. Furthermore, the effects of overexpressed miR-126-3p derived from BMSCs exosomes on proliferation, migration, invasion, apoptosis, tumor growth, and metastasis of pancreatic cancer cells were analyzed in connection with lentiviral packaged miR-126-3p in vivo. Restored miR-126-3p was observed to suppress pancreatic cancer through downregulating ADAM9. Notably, overexpressed miR-126-3p derived from BMSCs exosomes inhibited the proliferation, invasion, and metastasis of pancreatic cancer cells, and promoted their apoptosis both in vitro and in vivo. Taken together, the key findings of the study indicated that overexpressed miR-126-3p derived from BMSCs exosomes inhibited the development of pancreatic cancer through the downregulation of ADAM9, highlighting the potential of miR-126-3p as a novel biomarker for pancreatic cancer treatment.

ADAM9 expression promotes an aggressive lung adenocarcinoma phenotype

A disintegrin and metalloproteinase 9 (ADAM9) possesses potent metastasis-inducing capacities and is highly expressed in several cancer cells. Previous work has shown that ADAM9 participates in the adhesive-invasive phenotype in lung cancer cells in vitro. In this study, we evaluated whether ADAM9 expression plays a critical role in metastatic processes in vivo and in angiogenesis. We first found that high ADAM9 expression was correlated with poor lung adenocarcinoma patient prognosis on Prognoscan data base. In vivo model based on intravenous injection in nude mice showed that a stable downregulation of ADAM9 in A549 (TrA549 A9-) cells was associated with a lower number of nodules in the lung, suggesting lower potentials for extravasation and metastasis. On a subcutaneous xenograft we showed that TrA549 A9- produced significantly smaller tumours and exhibited fewer neovessels. In addition, in vitro human umbilical vein endothelial cells exposed to supernatant from TrA549 A9- could reduce the formation of more vessel-like structures. To further understand the mechanism, a human antibody array analysis confirmed that five cytokines were downregulated in TrA549 A9- cells. Interleukin 8 was the most significantly downregulated, and its interaction with CXCR2 was implicated in angiogenesis on an in vitro model. These results emphasize the critical influence of ADAM9 on lung cancer progression and aggressiveness. ADAM9 should at least be a marker of cancer aggressiveness and a potential therapeutic target for cancer treatment.

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.

miRNA-520f Reverses Epithelial-to-Mesenchymal Transition by Targeting ADAM9 and TGFBR2

Reversing epithelial-to-mesenchymal transition (EMT) in cancer cells has been widely considered as an approach to combat cancer progression and therapeutic resistance, but a limited number of broadly comprehensive investigations of miRNAs involved in this process have been conducted. In this study, we screened a library of 1120 miRNA for their ability to transcriptionally activate the E-cadherin gene CDH1 in a promoter reporter assay as a measure of EMT reversal. By this approach, we defined miR-520f as a novel EMT-reversing miRNA. miR-520f expression was sufficient to restore endogenous levels of E-cadherin in cancer cell lines exhibiting strong or intermediate mesenchymal phenotypes. In parallel, miR-520f inhibited invasive behavior in multiple cancer cell systems and reduced metastasis in an experimental mouse model of lung metastasis. Mechanistically, miR-520f inhibited tumor cell invasion by directly targeting ADAM9, the TGFβ receptor TGFBR2 and the EMT inducers ZEB1, ZEB2, and the snail transcriptional repressor SNAI2, each crucial factors in mediating EMT. Collectively, our results show that miR-520f exerts anti-invasive and antimetastatic effects in vitro and in vivo, warranting further study in clinical settings. Cancer Res; 77(8); 2008-17. ©2017 AACR.

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 silencing inhibits breast tumor cells transmigration through blood and lymphatic endothelial cells

ADAMs are transmembrane multifunctional proteins that contain disintegrin and metalloprotease domains. ADAMs act in a diverse set of biological processes, including fertilization, inflammatory responses, myogenesis, cell migration, cell proliferation and ectodomain cleavage of membrane proteins. These proteins also have additional functions in pathological processes as cancer and metastasis development. ADAM9 is a member of ADAM protein family that is overexpressed in several types of human carcinomas. The aim of this study was to investigate the role of ADAM9 in hematogenous and lymphatic tumor cell dissemination assisting the development of new therapeutic tools. The role of ADAM9 in the interaction of breast tumor cells (MDA-MB-231) and endothelial cells was studied through RNA silencing. ADAM9 silencing in MDA-MB-231 cells had no influence in expression of several genes related to the metastatic process such as ADAM10, ADAM12, ADAM17, cMYC, MMP9, VEGF-A, VEGF-C, osteopontin and collagen XVII. However, there was a minor decrease in ADAM15 expression but an increase in that of MMP2. Moreover, ADAM9 silencing had no effect in the adhesion of MDA-MB-231 cells to vascular (HMEC-1 and HUVEC) and lymphatic cells (HMVEC-dLyNeo) under flow condition. Nevertheless, siADAM9 in MDA-MB-231 decreased transendothelial cell migration in vitro through HUVEC, HMEC-1 and HMVEC-dLyNeo (50%, 40% and 32% respectively). These results suggest a role for ADAM9 on the extravasation step of the metastatic cascade through both blood and lymph vessels.

Disruption and inactivation of the PP2A complex promotes the proliferation and angiogenesis of hemangioma endothelial cells through activating AKT and ERK

Hemangioma is a benign vascular neoplasm of unknown etiology. In this study, we generated an endothelial-specific PyMT gene-expressing transgenic mouse model that spontaneously develops hemangioma. Based on this transgenic model, a specific binding between PyMT and the core AC dimer of protein phosphatase 2A (PP2A) was verified in hemangioma vascular endothelial cells. The binding between PyMT and the PP2A AC dimer resulted in dissociation of the B subunit from the PP2A complex and inactivation of PP2A phosphatases, which in turn activated AKT and ERK signaling and promoted cell proliferation, migration and angiogenesis in vitro and tumorigenesis in vivo. Consistent with the in vitro findings, decreased PP2A phosphatase activity and disruption of the PP2A heterotrimeric complex were also observed in both primary transgene-positive TG(+) mouse hemangioma endothelial cells (TG(+) HEC cells) and human proliferating phase hemangioma endothelial (human HEC-P) cells, but not in transgene-negative TG(-) mouse normal vascular endothelial cells (TG(-) NEC cells) and human involuting phase hemangioma endothelial (human HEC-I) cells. Further, it was observed that in human hemangioma cells, endoglin could compete with the PP2A/A, C subunits for binding to the PP2A/B subunit, thereby resulting in dissociation of the B subunit from the PP2A complex. Treatment of Tie2/PyMT transgenic mice with the PP2A activator FTY720 significantly delayed the occurrence of hemangioma. Our data provide evidence of a previously unreported anti-proliferation and anti-angiogenesis effect of PP2A in vascular endothelial cells, and show the therapeutic value of PP2A activators in hemangioma.

Disintegrin and metalloproteinases (ADAMs) expression in gastroesophageal reflux disease and in esophageal adenocarcinoma

BACKGROUND

Clinically useful marker molecules for the progression of gastroesophageal reflux disease and Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC) are lacking. Many adenocarcinomas and inflammatory conditions exhibit increased expression of ADAMs, 'a disintegrin and metalloproteinases'.

METHODS

We assessed the expression of five ADAMs (9, 10, 12, 17, 19) in three esophageal cell lines (Het-1A, OE19, OE33) by RT-PCR and Western blotting, and in human samples of normal esophagus, esophagitis, BE, Barrett's dysplasia, and EAC by RT-PCR, and in selected samples by immunohistochemistry.

RESULTS

EAC patients showed increased mRNA expression of ADAMs 9, 12, 17 and 19, as compared to controls. At immunohistochemistry, ADAM9 and ADAM10 proteins were increased in EAC. Patient samples also showed increased mRNA expression of ADAM12 in esophagitis, of ADAM9 in BE, and of ADAMs 9, 12 and 19 in Barrett's dysplasia, as compared to controls. Two EAC cell lines showed increased ADAM9 mRNA.

CONCLUSIONS

ADAM9 expression is increased in EAC. Its predecessors show increased ADAM9 mRNA expression. The importance of the alterations in ADAM expression for the development of EAC, and their use as marker molecules, warrant further studies.

Combined RNAi targeting human Stat3 and ADAM9 as gene therapy for non-small cell lung cancer

Previous studies have demonstrated that human signal transducer and activator of transcription 3 (Stat3) and disintegrin and metalloproteinase 9 (ADAM9) are promising targets for RNA interference (RNAi)-based gene therapy for human non-small cell lung cancer (NSCLC). Thus, in the present study, the recombinant lentiviral (Lv) small hairpin (sh)RNA expression plasmids Lv/sh-Stat3 and Lv/sh-ADAM9, which targeted Stat3 and ADAM9, respectively, were constructed and subsequently infected into the A549 human NSCLC cell line. Cell proliferation, migration, invasion and apoptosis were determined in vitro in A549 cells following treatment with Lv/sh-Stat3 or Lv/sh-ADAM9 alone or in combination. In addition, the combined effect of Lv/sh-Stat3 and Lv/sh-ADAM9 gene therapy was evaluated in vivo using A549 xenograft models in nude mice. The in vitro experiments demonstrated that A549 cells treated with a combination of Lv/sh-Stat3 and Lv/sh-ADAM9 exhibited a significant additive effect in their cell proliferation, migration, invasion and apoptosis abilities, compared with A549 cells treated with Lv/sh-Stat3 or Lv/sh-ADAM9 alone. The in vivo experiments conducted in A549 xenograft tumor mouse models revealed that the combined treatment with Lv/sh-Stat3 and Lv/sh-ADAM9 exerted an additive effect on tumor growth inhibition, compared with the treatment with Lv/sh-Stat3 or Lv/sh-ADAM9 alone. These results suggested that combined RNAi gene therapy targeting human Stat3 and ADAM9 may be a novel and promising strategy for the treatment of NSCLC.

Preferred SH3 domain partners of ADAM metalloproteases include shared and ADAM-specific SH3 interactions

A disintegrin and metalloproteinases (ADAMs) constitute a protein family essential for extracellular signaling and regulation of cell adhesion. Catalytic activity of ADAMs and their predicted potential for Src-homology 3 (SH3) domain binding show a strong correlation. Here we present a comprehensive characterization of SH3 binding capacity and preferences of the catalytically active ADAMs 8, 9, 10, 12, 15, 17, and 19. Our results revealed several novel interactions, and also confirmed many previously reported ones. Many of the identified SH3 interaction partners were shared by several ADAMs, whereas some were ADAM-specific. Most of the ADAM-interacting SH3 proteins were adapter proteins or kinases, typically associated with sorting and endocytosis. Novel SH3 interactions revealed in this study include TOCA1 and CIP4 as preferred partners of ADAM8, and RIMBP1 as a partner of ADAM19. Our results suggest that common as well as distinct mechanisms are involved in regulation and execution of ADAM signaling, and provide a useful framework for addressing the pathways that connect ADAMs to normal and aberrant cell behavior.

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.

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 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.

The role and clinical implications of microRNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is common and one of the most aggressive of all human cancers. Recent studies have indicated that miRNAs, a class of small noncoding RNAs that regulate gene expression post-transcriptionally, directly contribute to HCC by targeting many critical regulatory genes. Several miRNAs are involved in hepatitis B or hepatitis C virus replication and virus-induced changes, whereas others participate in multiple intracellular signaling pathways that modulate apoptosis, cell cycle checkpoints, and growth-factor-stimulated responses. When disturbed, these pathways appear to result in malignant transformation and ultimately HCC development. Recently, miRNAs circulating in the blood have acted as possible early diagnostic markers for HCC. These miRNA also could serve as indicators with respect to drug efficacy and be prognostic in HCC patients. Such biomarkers would assist stratification of HCC patients and help direct personalized therapy. Here, we summarize recent advances regarding the role of miRNAs in HCC development and progression. Our expectation is that these and ongoing studies will contribute to the understanding of the multiple roles of these small noncoding RNAs in liver tumorigenesis.

Snake venom disintegrins and cell migration

Cell migration is a key process for the defense of pluricellular organisms against pathogens, and it involves a set of surface receptors acting in an ordered fashion to contribute directionality to the movement. Among these receptors are the integrins, which connect the cell cytoskeleton to the extracellular matrix components, thus playing a central role in cell migration. Integrin clustering at focal adhesions drives actin polymerization along the cell leading edge, resulting in polarity of cell movement. Therefore, small integrin-binding proteins such as the snake venom disintegrins that inhibit integrin-mediated cell adhesion are expected to inhibit cell migration. Here we review the current knowledge on disintegrin and disintegrin-like protein effects on cell migration and their potential use as pharmacological tools in anti-inflammatory therapy as well as in inhibition of metastatic invasion.