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

Exploring the oncogenic and tumor-suppressive roles of Circ-ADAM9 in cancer

Circular RNAs (circRNAs) constitute a recently identified category of closed continuous loop RNA transcripts, serving as a subset of competing endogenous RNAs (ceRNAs) with the capacity to modulate genes by acting as microRNA sponges. In the context of cancer growth, numerous investigations have explored the potential functions of circRNAs, revealing their diverse functions either as oncogenes, promoting cancer progression, or as tumor suppressors, mitigating disease development. Among these, circRNA ADAM9 (Circ-ADAM9) is now recognized as an important player in a variety of mechanisms, both physiological and pathological, especially in cancer. The aberrant expression of Circ-ADAM9 has been observed across multiple human malignancies, implying a significant involvement in tumorigenesis. This comprehensive review aims to synthesize recent findings elucidating the function of Circ-ADAM9 in many malignancies. Additionally, the review explores the possibility of Circ-ADAM9 as a valuable biomarker, offering insights into its prognostic, diagnostic, and therapeutic implications. By summarizing the latest discoveries in this field, the review contributes to our understanding of the multifaceted contribution of Circ-ADAM9 in tumor biology and its potential applications in clinical settings.

The entanglement of extracellular matrix molecules and immune checkpoint inhibitors in cancer: a systematic review of the literature

Introduction

Immune-checkpoint inhibitors (ICIs) have emerged as a core pillar of cancer therapy as single agents or in combination regimens both in adults and children. Unfortunately, ICIs provide a long-lasting therapeutic effect in only one third of the patients. Thus, the search for predictive biomarkers of responsiveness to ICIs remains an urgent clinical need. The efficacy of ICIs treatments is strongly affected not only by the specific characteristics of cancer cells and the levels of immune checkpoint ligands, but also by other components of the tumor microenvironment, among which the extracellular matrix (ECM) is emerging as key player. With the aim to comprehensively describe the relation between ECM and ICIs' efficacy in cancer patients, the present review systematically evaluated the current literature regarding ECM remodeling in association with immunotherapeutic approaches.

Methods

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and was registered at the International Prospective Register of Systematic Reviews (PROSPERO, CRD42022351180). PubMed, Web of Science, and Scopus databases were comprehensively searched from inception to January 2023. Titles, abstracts and full text screening was performed to exclude non eligible articles. The risk of bias was assessed using the QUADAS-2 tool.

Results

After employing relevant MeSH and key terms, we identified a total of 5070 studies. Among them, 2540 duplicates, 1521 reviews or commentaries were found and excluded. Following title and abstract screening, the full text was analyzed, and 47 studies meeting the eligibility criteria were retained. The studies included in this systematic review comprehensively recapitulate the latest observations associating changes of the ECM composition following remodeling with the traits of the tumor immune cell infiltration. The present study provides for the first time a broad view of the tight association between ECM molecules and ICIs efficacy in different tumor types, highlighting the importance of ECM-derived proteolytic products as promising liquid biopsy-based biomarkers to predict the efficacy of ICIs.

Conclusion

ECM remodeling has an important impact on the immune traits of different tumor types. Increasing evidence pinpoint at ECM-derived molecules as putative biomarkers to identify the patients that would most likely benefit from ICIs treatments.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022351180, identifier CRD42022351180.

Domatinostat Targets the FOXM1-Survivin Axis to Reduce the Viability of Ovarian Cancer Cells Alone and in Combination with Chemotherapeutic Agents

The deregulation of the FOXM1 transcription factor is a key molecular alteration in ovarian cancer, contributing to the development and progression of ovarian cancer via activation of the target genes. As such, FOXM1 is a highly attractive therapeutic target in the treatment of ovarian cancer, but there has been no clinically tested FOXM1 inhibitor to date. We investigated in this study the effects of domatinostat, a class I-selective HDAC inhibitor currently in the clinical stage of development as a cancer therapeutic, on the expression of FOXM1 and viability of ovarian cancer cells. Cell viability, as well as protein and mRNA expression of FOXM1 and its transcriptional target survivin, was examined after domatinostat treatment of TOV21G and SKOV3 ovarian cancer cell lines in the absence or presence of cisplatin and paclitaxel. The effect of FOXM1 knockdown on survivin expression and those of genetic and pharmacological inhibition of survivin alone or in combination with the chemotherapeutic agents on cell viability were also examined. Domatinostat reduced the protein and mRNA expression of FOXM1 and survivin and also the viability of ovarian cancer cells alone and in combination with cisplatin or paclitaxel at clinically relevant concentrations. Knockdown experiments showed survivin expression was dependent on FOXM1 in ovarian cancer cells. Survivin inhibition was sufficient to reduce the viability of ovarian cancer cells alone and in combination with the chemotherapeutic agents. Our findings suggest that domatinostat, which effectively targets the FOXM1-survivin axis required for the viability of ovarian cancer cells, is a promising option for the treatment of ovarian cancer.

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).

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.

An Overview of ADAM9: Structure, Activation, and Regulation in Human Diseases

ADAM9 (A disintegrin and a metalloprotease 9) is a membrane-anchored protein that participates in a variety of physiological functions, primarily through the disintegrin domain for adhesion and the metalloprotease domain for ectodomain shedding of a wide variety of cell surface proteins. ADAM9 influences the developmental process, inflammation, and degenerative diseases. Recently, increasing evidence has shown that ADAM9 plays an important role in tumor biology. Overexpression of ADAM9 has been found in several cancer types and is correlated with tumor aggressiveness and poor prognosis. In addition, through either proteolytic or non-proteolytic pathways, ADAM9 promotes tumor progression, therapeutic resistance, and metastasis of cancers. Therefore, comprehensively understanding the mechanism of ADAM9 is crucial for the development of therapeutic anti-cancer strategies. In this review, we summarize the current understanding of ADAM9 in biological function, pathophysiological diseases, and various cancers. Recent advances in therapeutic strategies using ADAM9-related pathways are presented as well.

Knockdown of ADAMDEC1 inhibits the progression of glioma in vitro

BACKGROUND

Glioma is one of the most lethal malignant tumors all over the world. The prognosis of patients with high‑grade glioma remains very poor. Therefore, it is urgent to find a novel strategy for the treatment of glioma. It has been reported that ADAMDEC1 could regulate the progression of multiple diseases, including cancers. However, the role of ADAMDEC1 during the tumorigenesis of glioma remains largely unknown. Methods, Gene expression of ADAMDEC1 in glioma tissues or in cells was detected by qRT-PCR. Western blot was performed to measure the protein expressions of p53, active caspase3, active caspase9, CDK2 and Cyclin A in glioma cells. Cell proliferation was detected by CCK-8 assay. Cell apoptosis or cycle was tested by flow cytometry. Transwell was used to test the invasion of glioma cells.

RESULTS

The expression of ADAMDEC1 in glioma tissues or cells was significantly upregulated. In addition, downregulation of ADAMDEC1 notably inhibited the proliferation and induced apoptosis of glioma cells through upregulation of active caspase 3 and active caspase 9. Besides, silencing of ADAMDEC1 obviously induced G1 arrest in glioma cells via modulation of cell cycle-related proteins. Finally, knockdown of ADAMDEC1 significantly inhibited the migration and invasion of glioma cells. In contrast, overexpression of ADAMDEC1 promoted cell proliferation, migration and invasion of glioma cells.

CONCLUSION

Downregulation of ADAMDEC1 could significantly inhibit the tumorigenesis of glioma in vitro, which may serve as a novel target for the treatment of glioma.

Effect of miR-26b-5p on cis-diamine dichloroplatinum-induced ovarian granulosa cell injury by targeting MAP3K9

The proliferation and differentiation of granulosa cells are very important for follicular development. The dysfunction of granulosa cells leading to follicular development is an important cause of ovarian endocrine abnormalities. More and more evidence shows that microRNAs are involved in the regulation of ovarian granulosa cell function. It has been found that MiR-26b may be involved in CDDP resistance. Studies have shown that miR-26b can promote apoptosis of ovarian granulosa cells, but there are few studies on its mechanism, and no studies have been found on the damage of miR-26b-5p to rat ovarian granulosa cells induced by CDDP. Identification of ovarian granulosa cells was conducted by immunochemical staining. Cell counting kit 8 (CCK-8) was used to detect cell viability, flow cytometry was used to detect cell apoptosis, quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot (WB) were used to analyze the expression of miR-26b-5p, MAP3K9, cleaved Caspase-3, Bax, and Bcl-2; dual-luciferase reporter assay results further verify the targeting relation between miR-26b-5p and MAP3K9. CDDP remarkably inhibited ovarian granulosa cell viability and induced ovarian granulosa cell apoptosis; miR-26b-5p inhibitor enhanced viability and inhibited apoptosis of ovarian granulosa cells, which treated with CDDP, but had little effect on normal cells. MAP3K9 partially reversed the effect of miR-26b-5p on ovarian granulosa cells induced by CDDP. miR-26b-5p has a protective effect on CDDP-induced ovarian granulosa cells via targeting MAP3K9.

Long noncoding RNA CASC9 promotes the proliferation and metastasis of papillary thyroid cancer via sponging miR-488-3p

Cancer susceptibility candidate 9 (CASC9) is a recently identified lncRNA that acted as a tumor promotor in diversified cancer types. However, its role in papillary thyroid cancer (PTC) remains unknown. The expression of CASC9 was measured in 52 human PTC tissues and PTC cell lines as well as their controls. The proliferation, migration, and invasion of PTC cells were determined after knockdown or overexpression of CASC9 to evaluate the effect of CASC9 on PTC cells. Also, the role of PTC tumorigenesis was confirmed in mice xenograft models. Additionally, the underlying mechanisms of CASC9 were further researched. We found that CASC9 expression was augmented in human PTC tissues and cells. Higher CASC9 expression was associated with large tumor size, advanced stage, or lymph node metastasis. Downregulation of CASC9 significantly attenuated the proliferative, migrative, and invasive abilities of PTC cells, and suppressed tumorigenesis in vivo. While overexpression of CASC9 elevated the proliferation, migration, and invasion of PTC cells. miR‐488‐3p expression was decreased, and ADAM9 level was increased in PTC tissues and cells. CASC9 expression was negatively related to miR‐488‐3p, but positively associated with ADAM9 expression in PTC tissues. Molecular mechanism analysis revealed that CASC9 functioned via sponging miR‐488‐3p to regulate ADAM9 expression, followed by activation of EGFR‐Akt signaling. In conclusion, lncRNA CASC9 promoted the malignant phenotypes of PTC via modulating miR‐488‐3p/ADAM9 pathway. This study may provide a novel therapeutic target for the treatment of PTC.

Aberrant expression of ADAM9 in ovarian cancer and its clinical significance

Background

The oncogene a disintegrin and metalloproteinase 9 (ADAM9) was up‐regulated in ovarian cancer tissues, and the present study aims to explore the potential diagnostic and prognostic value of ADAM9 in ovarian cancer (OC).

Methods

A total of 30 paired fresh OC tumor tissues and the paired‐adjacent normal tissue, and 90 formalin‐fixed paraffin‐embedded (FFPE) OC samples and adjacent normal tissue were collected. The expression of OC in FFPE samples was examined by immunohistochemical methods, and the mRNA expression of ADAM9 in fresh tumor samples was examined by RT‐qPCR methods. Receiver operating characteristics curve was drawn to analyze the potential diagnostic value of ADAM9. Kaplan‐Meier survival analysis was performed to compare the overall survival (OS) and disease‐free survival (DFS) of the ADAM9 positive and negative OC patients.

Results

The positive rate of ADAM9 in FFPE OC tumor tissue was markedly higher than in the non‐tumorous tissue (61/90 vs 47/90), and increased expression level of ADAM9 may associate with higher histological grade, advanced Figo stage and increased risk of metastasis; moreover, the mRNA expression of ADAM9 was also increased in OC tissue compared with the normal tissue (P < .001), and results of ROC analysis suggested that ADAM9 is a sensitive marker for the diagnosis of OC( AUC 0.8389, 95% confidence interval 0.7333 to 0.9445); finally, increased expression of ADAM9 may indicate decreased OS (P = .004) and DFS (P = .014) of the patients.

Conclusion

A disintegrin and metalloproteinase 9 was up‐regulated in OC, and ADAM9 may serve as potential diagnostic and prognostic marker for the diagnosis and treatment of OC.

ADAM proteases: Emerging role and targeting of the non-catalytic domains

ADAM proteases are multi domain transmembrane metalloproteases that cleave a range of cell surface proteins and activate signaling pathways implicated in tumor progression, including those mediated by Notch, EFGR, and the Eph receptors. Consequently, they have emerged as key therapeutic targets in the efforts to inhibit tumor initiation and progression. To that end, two main approaches have been taken to develop ADAM antagonists: (i) small molecule inhibitors, and (ii) monoclonal antibodies. In this mini-review we describe the distinct features of ADAM proteases, particularly of ADAM10 and ADAM17, their domain organization, conformational rearrangements, regulation, as well as their emerging importance as therapeutic targets in cancer. Further, we highlight an anti-ADAM10 monoclonal antibody that we have recently developed, which has shown significant promise in inhibiting Notch signaling and deterring growth of solid tumors in pre-clinical settings.

Metalloproteinases and their roles in human cancer

It is now widely appreciated that members of the matrix metalloproteinase (MMP) family of enzymes play a key role in cancer development and progression along with many of the hallmarks associated with them. The activity of these enzymes has been directly implicated in extracellular matrix remodeling, the processing of growth factors and receptors, the modulation of cell migration, proliferation, and invasion, the epithelial to mesenchymal transition, the regulation of immune responses, and the control of angiogenesis. Certain MMP family members have been validated as biomarkers of a variety of human cancers including those of the breast, brain, pancreas, prostate, ovary, and others. The related metalloproteinases, the A disintegrin and metalloproteinases (ADAMs), share a number of these functions as well. Here, we explore these essential metalloproteinases and some of their disease-associated activities in detail as well as some of their complementary translational potential. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc.

USP39 promotes ovarian cancer malignant phenotypes and carboplatin chemoresistance

Ubiquitin‑specific protease 39 (USP39), as one of the deubiquitinating enzymes (DUBs), exhibits aberrant an expression and has oncogenic functions in several types of cancer. However, the function and underlying molecular mechanisms of action of USP39 in ovarian cancer remain largely undetermined. The present study thus aimed to investigate whether USP39 is a promising tumor‑associated gene and whether it could be a viable target for overcoming chemotherapeutic resistance in ovarian cancer. The present study identified that USP39 was highly expressed in ovarian cancer samples with carboplatin resistance. A series of functional assays revealed that the knockdown of USP39 in ES2 and SKOV3 cells significantly decreased cell proliferation, induced cell cycle arrest at the G2/M phase and impaired the cell colony formation ability. USP39 deficiency enhanced the carboplatin‑induced apoptosis of the SKOV3 cells via the activation of poly‑ADP ribose polymerase and caspase‑3. USP39 knockdown led to the inhibition of cell migration and invasion. The opposite effects were observed when USP39 was overexpressed in the ES2 and SKOV3 cells. In vivo animal models revealed that the subcutaneous transplantation and intraperitoneal injection of USP39‑overexpressing ES2 cells increased tumor burden with or without treatment with carboplatin. However, the knockdown of USP39 suppressed SKOV3 cell growth in vivo. Mechanistic analyses also demonstrated that USP39 induced the phosphorylation of extracellular signal‑regulated kinase and AKT and increased the expression of epidermal growth factor receptor and cyclin B1. Collectively, the findings of this study suggest that USP39 may paly a vital role in regulating ovarian cancer malignant phenotypes and carboplatin resistance. Therefore, USP39 may prove to be a promising therapeutic target for patients with ovarian cancer.

ADAM9 contributes to vascular invasion in pancreatic ductal adenocarcinoma

A disintegrin and a metalloprotease (ADAM)‐9 is a metzincin cell‐surface protease with strongly elevated expression in solid tumors, including pancreatic ductal adenocarcinoma (PDAC). In this study, we performed immunohistochemistry (IHC) of a tissue microarray (TMA) to examine the expression of ADAM9 in a cohort of >100 clinically annotated PDAC cases. We report that ADAM9 is prominently expressed by PDAC tumor cells, and increased ADAM9 expression levels correlate with poor tumor grading (P = 0.027) and the presence of vasculature invasion (P = 0.017). We employed gene expression silencing to generate a loss‐of‐function system for ADAM9 in two established PDAC cell lines. In vitro analysis showed that loss of ADAM9 does not impede cellular proliferation and invasiveness in basement membrane. However, ADAM9 plays a crucial role in mediating cell migration and adhesion to extracellular matrix substrates such as fibronectin, tenascin, and vitronectin. This effect appears to depend on its catalytic activity. In addition, ADAM9 facilitates anchorage‐independent growth. In AsPC1 cells, but not in MiaPaCa‐2 cells, we noted a pronounced yet heterogeneous impact of ADAM9 on the abundance of various integrins, a process that we characterized as post‐translational regulation. Sprout formation of human umbilical vein endothelial cells (HUVECs) is promoted by ADAM9, as examined by transfer of cancer cell conditioned medium; this finding further supports a pro‐angiogenic role of ADAM9 expressed by PDAC cancer cells. Immunoblotting analysis of cancer cell conditioned medium highlighted that ADAM9 regulates the levels of angiogenic factors, including shed heparin‐binding EGF‐like growth factor (HB‐EGF). Finally, we carried out orthotopic seeding of either wild‐type AsPC‐1 cells or AsPC‐1 cells with silenced ADAM9 expression into murine pancreas. In this in vivo setting, ADAM9 was also found to foster angiogenesis without an impact on tumor cell proliferation. In summary, our results characterize ADAM9 as an important regulator in PDAC tumor biology with a strong pro‐angiogenic impact.

Clear cell carcinoma of the ovary: Clinicopathologic features and outcomes in a Chinese cohort

This retrospective analysis aimed to clarify the clinical and pathologic features of ovarian clear cell carcinoma (OCCC), and to determine the factors predictive of survival.Data waereextracted from OCCC patients who underwent primary surgery followed by adjuvant chemotherapy in Obstetrics & Gynecology Hospital of Fudan University between January2007 and December 2014. Kaplan-Meier survival estimates and Cox proportional hazards model were used for survival analyses.Of 130 patients (mean age = 56.2 years), 66.2% had stage I disease when the 5-year overall survival and 5-year disease-free survival were 89.2% and 88.1%, respectively. Patients frequently presented with large pelvic mass (>10 cm) and mild-to-moderate elevation of serological CA125 (≤200U/ mL). 60.7% of the cases at stage III/IV exhibited resistance to platinum-based chemotherapy; 37.69% of the tumors arose from endometriosis. On multivariate analysis, stage and chemoresistance were independent prognostic factors predictive for poorer survival. Survival at stage IC1 (surgical rupture) was comparable to that at stage IA (capsule intact), whereas survival at stage IC2/IC3 (rupture before surgery) was significantly worse than that at stage IA.OCCC shows distinct features compared to other epithelial ovarian cancers. FIGO stage and response to chemotherapy affect prognosis independently. Arising from endometriosis is not associated with better survival. Preoperative rupture rather than intraoperative rupture confers an adverse prognosis in otherwise stage IA disease.

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.