A disintegrin and metalloprotease 12 (ADAM12) is a prognostic factor in resected pathological stage I lung adenocarcinoma

Depletion of slow-cycling PDGFRα+ADAM12+ mesenchymal cells promotes antitumor immunity by restricting macrophage efferocytosis

The capacity to survive and thrive in conditions of limited resources and high inflammation is a major driver of tumor malignancy. Here we identified slow-cycling ADAM12+PDGFRα+ mesenchymal stromal cells (MSCs) induced at the tumor margins in mouse models of melanoma, pancreatic cancer and prostate cancer. Using inducible lineage tracing and transcriptomics, we demonstrated that metabolically altered ADAM12+ MSCs induced pathological angiogenesis and immunosuppression by promoting macrophage efferocytosis and polarization through overexpression of genes such as Gas6, Lgals3 and Csf1. Genetic depletion of ADAM12+ cells restored a functional tumor vasculature, reduced hypoxia and acidosis and normalized CAFs, inducing infiltration of effector T cells and growth inhibition of melanomas and pancreatic neuroendocrine cancer, in a process dependent on TGF-β. In human cancer, ADAM12 stratifies patients with high levels of hypoxia and innate resistance mechanisms, as well as factors associated with a poor prognosis and drug resistance such as AXL. Altogether, our data show that depletion of tumor-induced slow-cycling PDGFRα+ MSCs through ADAM12 restores antitumor immunity.

ADAM12 promotes the resistance of lung adenocarcinoma cells to EGFR-TKI and regulates the immune microenvironment by activating PI3K/Akt/mTOR and RAS signaling pathways

Lung adenocarcinoma (LUAD) is a malignant respiratory disease, resulting in a heavy social burden. Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance and tumor immune microenvironment are important directions in the treatment of LUAD. In this study, we confirmed the role of ADAM metallopeptidase domain 12 (ADAM12) in LUAD development and progression. Our bioinformatic analysis was conducted to screen ADAM12 was correlated with EGFR-TKI and immune infiltration in LUAD patients. Our results showed that the transcription and post-transcription level of ADAM12 is significantly increased in tumor samples compared to normal samples, and ADAM12 correlated with poor prognosis in LUAD patients. High level of ADAM12 accelerated the LUAD progression via promoting proliferation, cell cycle, apoptosis escaping, immune escaping, EGFR-TKI resistance, angiogenesis, invasion and migration based on experiment validation in vitro and in vivo, which could be attenuated by ADAM12 knockdown. Further mechanistic studies suggested that the PI3K/Akt/mTOR and RAS signaling pathways were activated after ADAM12 knockdown. Therefore, ADAM12 might be validated as a possible molecular therapy target and prognostic marker for patients with LUAD.

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

Background

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

Methods

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

Results

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

Conclusions

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

Supplementary Information

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

ADAM12 as a Clinical Prognostic Indicator Associated with Tumor Immune Infiltration in Lung Adenocarcinoma

Twenty-two functional α-disintegrin and metalloproteinases (ADAMs) have been identified in humans, 12 of which have proteolytic activity. The role of ADAMs in cancer has attracted increasing attention. However, the expression and significance of ADAMs in lung adenocarcinoma (LUAD) remain unclear. Most recently, we investigated the transcriptional data of ADAMs and related overall survival in patients with LUAD based on several databases, including TCGA, cBioPortal, Kaplan-Meier Plotter, LinkedOmics, KEGG, TIMER, and TISIDB. Knockdown of ADAM12 was performed in vitro to verify its biological function. According to our findings, 10 ADAMs exhibited significant differential expression in LUAD compared with cancer-adjacent normal tissues. ADAM12 expression was significantly higher in LUAD tissues than in paracancerous tissues, and lower ADAM12 expression was associated with better survival. Genetic alterations of ADAM12 mainly included missense mutations, amplifications, and deep deletions. ADAM12 and positively correlated genes were mainly enriched in protein digestion and absorption, extracellular matrix-receptor interaction, and adhesion plaques. ADAM12 had a moderate correlation with immune cell markers EBIP1, CCNB1, EXO1, KNTC1, PRC1, and FAM198B. Prognostic model was established based on ADAM12 and immune-related genes. In vitro experiments revealed that knocking down ADAM12 inhibited cell proliferation, migration, and invasion. ADAM12 potentially plays an important role in the occurrence of LUAD and may be utilized as an immunotherapy target and a valuable prognostic biomarker for LUAD.

Identification of core genes and clinical outcomes in tumors originated from endoderm (gastric cancer and lung carcinoma) via bioinformatics analysis

ABSTRACT

During last decade, bioinformatics analysis has provided an effective way to study the relationship between various genes and biological processes. In this study, we aimed to identify potential core candidate genes and underlying mechanisms of progression of lung and gastric carcinomas which both originated from endoderm. The expression profiles, GSE54129 (gastric carcinoma) and GSE27262 (lung carcinoma), were collected from GEO database. One hundred eleven patients with gastric carcinoma and 21 health people were included in this research. Meanwhile, there were 25 lung carcinoma patients. Then, 75 differentially expressed genes were selected via GEO2R online tool and Venn software, including 31 up-regulated genes and 44 down-regulated genes. Next, we used Database for Annotation, Visualization, and Integrated Discovery and Metascpe software to analyze Kyoto Encyclopedia of Gene and Genome pathway and gene ontology. Furthermore, Cytoscape software and MCODE App were performed to construct complex of these differentially expressed genes . Twenty core genes were identified, which mainly enriched in extracellular matrix-receptor interaction, focal adhesion, and PI3K-Akt pathway (P < .01). Finally, the significant difference of gene expression between cancer tissues and normal tissues in both lung and gastric carcinomas was examined by Gene Expression Profiling Interactive Analysis database. Twelve candidate genes with positive statistical significance (P < .01), COMP CTHRC1 COL1A1 SPP1 COL11A1 COL10A1 CXCL13 CLDN3 CLDN1 matrix metalloproteinases 7 ADAM12 PLAU, were picked out to further analysis. The Kaplan-Meier plotter website was applied to examine relationship among these genes and clinical outcomes. We found 4 genes (ADAM12, SPP1, COL1A1, COL11A1) were significantly associated with poor prognosis in both lung and gastric carcinoma patients (P  < .05). In conclusion, these candidate genes may be potential therapeutic targets for cancer treatment.

The Significance of Secreted Phosphoprotein 1 in Multiple Human Cancers

Malignant tumor represents a major reason for death in the world and its incidence is growing rapidly. Developing the tools for early diagnosis is possibly a promising way to offer diverse therapeutic options and promote the survival chance. Secreted phosphoprotein 1 (SPP1), also called Osteopontin (OPN), has been demonstrated overexpressed in many cancers. However, the specific role of SPP1 in prognosis, gene mutations, and changes in gene and miRNA expression in human cancers is unclear. In this report, we found SPP1 expression was higher in most of the human cancers. Based on Kaplan-Meier plotter and the PrognoScan database, we found high SPP1 expression was significantly correlated with poor survival in various cancers. Using a large dataset of colon adenocarcinoma (COAD), head and neck cancer (HNSC), lung adenocarcinoma (LUAD), and lung squamous cell carcinoma (LUSC) patients from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases, this study identified 22 common genes and 2 common miRNAs. GO, and KEGG paths analyses suggested that SPP1 correlated genes were mainly involved in positive regulation of immune cell activation and infiltration. SPP1-associated genes and miRNAs regulatory networks suggested that their interactions may play a role in the progression of four selected cancers. SPP1 showed significant positive correlation with the immunocyte and immune marker sets infiltrating degrees. All of these data provide strong evidence that SPP1 may promote tumor progress through interacting with carcinogenic genes and facilitating immune cells’ infiltration in COAD, HNSC, LUAD, and LUSC.

ADAM12 silencing promotes cellular apoptosis by activating autophagy in choriocarcinoma cells

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

Differential roles of protease isoforms in the tumor microenvironment

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

An ADAM12 and FAK positive feedback loop amplifies the interaction signal of tumor cells with extracellular matrix to promote esophageal cancer metastasis

Esophageal squamous cell carcinomas (ESCCs) have a poor prognosis mostly due to early metastasis. To explore the early event of metastasis in ESCC, we established an in vitro selection model to mimic the interaction of tumor cells with extracellular matrix, through which a sub-line of ESCC cells with high invasive ability was generated. By comparing the gene expression profile of the highly invasive sub-line to that of the parental cells, ADAM12-L was identified as a candidate gene promoting ESCC cell invasion. Immunohistochemistry revealed that the ADAM12-L was overexpressed in human ESCC tissues, especially at cancer invasive edge, and ADAM12-L overexpression tightly correlated with increased metastasis and poor outcome of ESCC patients. Indeed, ADAM12-L knockdown reduced the invasion and metastasis of ESCC cells both in vitro and in vivo. Furthermore, we demonstrated that ADAM12-L participated in focal adhesion turnover and promoted the activation of focal adhesion kinase (FAK), which in turn increased ADAM12-L transcription through FAK/JNK/c-Jun axis. Therefore, a loop initiated from the cancer cell upon the engagement with extracellular matrix through FAK and c-Jun to enhance ADAM12-L expression is established, leading to the positive feedback of further FAK activation and prompting metastasis. Our study indicates that overexpression of ADAM12-L can serve as a precision marker to determine the activation of this loop. Targeting ADAM12-L to disrupt this positive feedback loop represents a promising strategy to treat the metastasis of esophageal cancers.

Association between ADAM12 Single-Nucleotide Polymorphisms and Knee Osteoarthritis: A Meta-Analysis

Objective

ADAM12 polymorphisms may be associated with the risk of knee osteoarthritis (KOA), but currently available evidence remains controversial. We performed this meta-analysis to confirm whether ADAM12 polymorphisms were associated with susceptibility of KOA.

Methods

A comprehensive literature search in PubMed, EMBASE, and ISI Web of Science was conducted to identify observational studies assessing the association between ADAM12 polymorphisms and susceptibility of KOA. The strength of association was indicated as odds ratio (OR) and the corresponding 95% confidence interval (95%CI). Four types of genetic model (additive model, dominant model, recessive model, and allele model) were evaluated for each included study. Subgroup analysis by ethnicity was performed.

Results

Seven case-control studies comprising a total of 3512 KOA patients and 5405 healthy controls were included in the meta-analysis. A significant association between rs1871054 and increased KOA risk was found in each genetic model. No significant association was found between KOA and rs3740199, rs1044122, or rs1278279 in any genetic model.

Conclusion

Based on the findings of our study, there was a modest but statistically significant association between rs1871054 and risk of KOA in Asian population, while other polymorphisms (rs3740199, rs1044122, or rs1278279) in ADAM12 were not associated with KOA in any population.

ADAM12 Is a Novel Regulator of Tumor Angiogenesis via STAT3 Signaling

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION AND DISCUSSION

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

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

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

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

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

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

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

Erbb2 up-regulation of ADAM12 expression accelerates skin cancer progression

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

Urinary concentrations of ADAM 12 from breast cancer patients pre- and post-surgery vs. cancer-free controls: a clinical study for biomarker validation

Background

The ADAMs (A Disintegrin and Metalloproteinases) are a family of multi-domain, zinc-dependent metalloproteinase enzymes. ADAM 12 has been previously associated with the onset and progression of breast cancer, and elevated levels of ADAM 12 have been previously found in the urine of breast cancer patients. Aims of the current study are: 1) establish the viability of urinary ADAM 12 as a diagnostic marker for breast cancer, and 2) explore the effects of surgical tumor removal on the levels of urinary ADAM 12.

Methods

A total of 96 patients have been recruited for this study, including 50 patients diagnosed with cancer, and 46 age-matched controls. Commercially available ELISA kits for ADAM 12 were used to quantify the presence and concentration of this enzyme in the urine from cancer patients with ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC) both prior to any treatment and approximately two weeks following surgery, as well as from controls.

Results

We find no statistically significant differences between the concentrations of ADAM 12 in the urine of breast cancer patients prior to treatment and that of their age-matched controls; however the concentration of ADAM 12, both alone and as a function of urine total protein, are significantly elevated following surgery (p < 0.0001). Patients who underwent a mastectomy have significantly higher urinary ADAM 12 concentrations than those who underwent a lumpectomy (significant at p = 0.0271).

Conclusions

These findings suggest that urinary ADAM 12 may not correlate directly with the status and stage of breast cancer as previously thought; rather these increases may be a result of tissue injury and inflammation from biopsy and surgical resection. Results of this study may suggest a need for biomarkers to be evaluated carefully in the context of tissue damage.

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

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

Alternative mRNA splicing generates two distinct ADAM12 prodomain variants

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

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

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

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

A disintegrin and metalloproteinase-12 (ADAM12): function, roles in disease progression, and clinical implications

BACKGROUND

A disintegrin and metalloproteinase-12 (ADAM12) is a member of the greater ADAM family of enzymes: these are multifunctional, generally membrane-bound, zinc proteases for which there are forty genes known (21 of these appearing in humans). ADAM12 has been implicated in the pathogenesis of various cancers, liver fibrogenesis, hypertension, and asthma, and its elevation or decrease in human serum has been linked to these and other physiological/pathological conditions.

SCOPE

In this review, we begin with a brief overview of the ADAM family of enzymes and protein structure. We then discuss the role of ADAM12 in the progression and/or diagnosis of various disease conditions, and we will conclude with an exploration of currently known natural and synthetic inhibitors.

MAJOR CONCLUSION

ADAM12 has potential to emerge as a successful drug target, although targeting the metalloproteinase domain with any specificity will be difficult to achieve due to structural similarity between the members of the ADAM and MMP family of enzymes. Overall, more research is required to establish ADAM12 being as a highly desirable biomarker and drug target of different diseases, and their selective inhibitors as potential therapeutic agents.

GENERAL SIGNIFICANCE

Given the appearance of elevated levels of ADAM12 in various diseases, particularly breast cancer, our understanding of this enzyme both as a biomarker and a potential drug target could help make significant inroads into both early diagnosis and treatment of disease.

Deregulation of the histone demethylase JMJD2A is involved in human carcinogenesis through regulation of the G(1)/S transition

Although a number of JmjC-containing histone demethylases have been identified and biochemically characterized, pathological roles of their dysfunction in human disease such as cancer have not been well elucidated. Here, we report the Jumonji domain containing 2A (JMJD2A) is integral to proliferation of cancer cells. Quantitative real-time PCR analysis revealed higher expression of JMJD2A in clinical bladder cancer tissues than in corresponding non-neoplastic tissues (P<0.0001). Immunohistochemical analysis also showed positive staining for JMJD2A in 288 out of 403 lung cancer cases, whereas no staining was observed in lung normal tissues. Suppression of JMJD2A expression in lung and bladder cancer cells overexpressing this gene, using specific siRNAs, inhibited incorporation of BrdU and resulted in significant suppression of cell growth. Furthermore, JMJD2A appears to directly transactivate the expression of some tumor associated proteins including ADAM12 through the regulation of histone H3K9 methylation. As expression levels of JMJD2A are low in normal tissues, it may be feasible to develop specific inhibitors targeting the enzyme as anti-tumor agents which should have a minimal risk of adverse reaction.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Lysophosphatidic acid-induced ADAM12 expression mediates human adipose tissue-derived mesenchymal stem cell-stimulated tumor growth

Lysophosphatidic acid (LPA) is involved in mesenchymal stem cell-stimulated tumor growth in vivo. However, the molecular mechanism by which mesenchymal stem cells promote tumorigenesis remains elusive. In the present study, we demonstrate that conditioned medium from A549 human lung adenocarcinoma cells (A549 CM) induced the expression of ADAM12, a disintegrin and metalloproteases family member, in human adipose tissue-derived mesenchymal stem cells (hASCs). A549 CM-stimulated ADAM12 expression was abrogated by pretreatment of hASCs with the LPA receptor 1 inhibitor Ki16425 or by small interfering RNA-mediated silencing of LPA receptor 1, suggesting a key role for the LPA-LPA receptor 1 signaling axis in A549 CM-stimulated ADAM12 expression. Silencing of ADAM12 expression using small interfering RNA or short hairpin RNA abrogated LPA-induced expression of both α-smooth muscle actin, a marker of carcinoma-associated fibroblasts, and ADAM12 in hASCs. Using a xenograft transplantation model of A549 cells, we demonstrated that silencing of ADAM12 inhibited the hASC-stimulated in vivo growth of A549 xenograft tumors and the differentiation of transplanted hASCs to α-smooth muscle actin-positive carcinoma-associated fibroblasts. LPA-conditioned medium from hASCs induced the adhesion of A549 cells and silencing of ADAM12 inhibited LPA-induced expression of extracellular matrix proteins, periostin and βig-h3, in hASCs and LPA-conditioned medium-stimulated adhesion of A549 cells. These results suggest a pivotal role for LPA-stimulated ADAM12 expression in tumor growth and the differentiation of hASCs to carcinoma-associated fibroblasts expressing α-smooth muscle actin, periostin, and βig-h3.

A positive feedback loop between HER2 and ADAM12 in human head and neck cancer cells increases migration and invasion

Increased activation of epidermal growth factor receptor (EGFR) family members such as HER2/Erbb2 can result in more aggressive disease, resistance to chemotherapy and reduced survival of head and neck squamous cell carcinoma (HNSCC) patients. In order to identify mechanisms through which these receptor tyrosine kinases accelerate tumor progression, the regulation of metalloprotease expression by EGFR family members was investigated in 11 SCC cell lines. HER2 expression was significantly correlated with ADAM12 (A Disintegrin And Metalloprotease 12) expression in these cell lines and was co-expressed in human head and neck cancers. Inhibition of HER2 or EGFR decreased ADAM12 transcripts while HER2 transfection up-regulated ADAM12 expression. To understand the molecular mechanisms underlying HER2 regulation of ADAM12, we investigated the signaling pathways directing ADAM12 production in SCC cells. Inhibition of phosphatidyl inositol-3-kinase (PI3K) or mammalian Target of Rapamycin (mTOR) decreased ADAM12 transcripts in HER2-expressing SCC cells, while transfection with AKT increased ADAM12 mRNA. Experiments utilizing ADAM12 transfection or siRNA targeting of ADAM12 revealed that the protease increased both the migration and invasiveness of oral SCC cells. Surprisingly, ADAM12 also increased HER2 message, protein levels, and activity through an Ets1-dependent mechanism. Collectively, these results reveal a novel positive activation loop between ADAM12 and HER2 that may contribute to HNSCC progression.

ADAM12 produced by tumor cells rather than stromal cells accelerates breast tumor progression

Expression of ADAM12 is low in most normal tissues but is markedly increased in numerous human cancers, including breast carcinomas. We have previously shown that overexpression of ADAM12 accelerates tumor progression in a mouse model of breast cancer (PyMT). In this study, we found that ADAM12 deficiency reduces breast tumor progression in the PyMT model. However, the catalytic activity of ADAM12 seems to be dispensable for its tumor-promoting effect. Interestingly, we show that ADAM12 endogenously expressed in tumor-associated stroma in the PyMT model does not influence tumor progression, but that ADAM12 expression by tumor cells is necessary for tumor progression in these mice. This finding is consistent with our observation that in human breast carcinoma, ADAM12 is almost exclusively located in tumor cells and, only rarely, seen in the tumor-associated stroma. We hypothesized, however, that the tumor-associated stroma may stimulate ADAM12 expression in tumor cells, on the basis of the fact that TGF-β1 stimulates ADAM12 expression and is a well-known growth factor released from tumor-associated stroma. TGF-β1 stimulation of ADAM12-negative Lewis lung tumor cells induced ADAM12 synthesis, and growth of these cells in vivo induced more than 200-fold increase in ADAM12 expression. Our observation that ADAM12 expression is significantly higher in the terminal duct lobular units (TDLU) adjacent to human breast carcinoma compared with TDLUs found in normal breast tissue supports our hypothesis that tumor-associated stroma triggers ADAM12 expression.

ADAM12 transmembrane and secreted isoforms promote breast tumor growth: a distinct role for ADAM12-S protein in tumor metastasis

Increased levels of ADAM12 have been reported in a variety of human cancers. We have previously reported that urinary ADAM12 is predictive of disease status in breast cancer patients and that ADAM12 protein levels in urine increase with progression of disease. On the basis of these findings, the goal of this study was to elucidate the contribution of ADAM12 in breast tumor growth and progression. Overexpression of both the ADAM12-L (transmembrane) and ADAM12-S (secreted) isoforms in human breast tumor cells resulted in a significantly higher rate of tumor take and increased tumor size. Cells expressing the enzymatically inactive form of the secreted isoform, ADAM12-S, had tumor take rates and tumor volumes similar to those of wild-type cells, suggesting that the tumor-promoting activity of ADAM12-S was a function of its proteolytic activity. Of the two isoforms, only the secreted isoform, ADAM12-S, enhanced the ability of tumor cells to migrate and invade in vitro and resulted in a higher incidence of local and distant metastasis in vivo. This stimulatory effect of ADAM12-S on migration and invasion was dependent on its catalytic activity. Expression of both ADAM12 isoforms was found to be significantly elevated in human malignant breast tissue. Taken together, our results suggest that ADAM12 overexpression results in increased tumor take, tumor size, and metastasis in vivo. These findings suggest that ADAM12 may represent a potential therapeutic target in breast cancer.

ADAM12 induces estrogen-independence in breast cancer cells

Antiestrogen therapy has been used successfully to prolong disease-free and overall survival of ER positive breast cancer patients. However, 50% of patients with ER+ tumors fail to respond to such therapy or eventually acquire resistance to endocrine therapy, resulting in tumor progression and mortality. It is imperative, therefore, to understand the mechanisms that lead to hormone refractory breast cancer in order to develop therapeutics that can modulate the resistance to antiestrogen therapy. The protease, ADAM12, can be detected in the urine of breast cancer patients and its levels correlate with disease status, stage, and cancer risk. Within the context of this study, the authors have investigated the role of the two distinct isoforms of ADAM12 in breast tumor cell proliferation and as potential mediators of endocrine resistance. Using stable clones of ADAM12-overexpressing MCF-7 cells, the authors analyzed proliferation rates of these ER+ breast tumor cells both in estrogen-depleted medium and in the presence of the antiestrogens, tamoxifen, and ICI 182,780. Acquired estrogen resistance in these cells was analyzed using phospho-RTK analysis. Upregulation and phosphorylation of proteins were detected via immunoprecipitation and immunoblotting. EGFR and MAPK inhibitors were used to explore the mechanism of acquired estrogen resistance in breast tumor cells. It was observed that overexpression of the two isoforms, transmembrane ADAM12-L, and secreted ADAM12-S, in breast tumor cells promoted estrogen-independent proliferation. In ADAM12-L-expressing cells, estrogen-independence was a direct result of increased EGFR expression and MAPK activation, whereas, the mechanism in ADAM12-S-expressing cells may be enhanced IGF-1R signaling. The importance of the EGFR signaling pathway in the estrogen-independent growth of ADAM12-L expressing cells was highlighted by the effect of EGFR inhibitors AG1478 and PD15035 or MAPK inhibitor U0126, each of which abolished the antiestrogen resistance in these cells. Taken together, these results demonstrate that ADAM12 isoforms confer a proliferative advantage to MCF-7 cells in the absence of estrogen stimulation, and suggest that downregulation of ADAM12 in combination with endocrine therapy may represent a useful pharmacological approach to breast cancer therapy.

The role of SnoN in transforming growth factor beta1-induced expression of metalloprotease-disintegrin ADAM12

Increased expression of metalloprotease-disintegrin ADAM12 is a hallmark of several pathological conditions, including cancer, cardiovascular disease, and certain inflammatory diseases of the central nervous system or the muscoskeletal system. We show that transforming growth factor beta1 (TGFbeta1) is a potent inducer of ADAM12 mRNA and protein in mouse fibroblasts and in mouse and human mammary epithelial cells. Induction of ADAM12 is detected within 2 h of treatment with TGFbeta1, is Smad2/Smad3-dependent, and is a result of derepression of the Adam12 gene. SnoN, a negative regulator of the TGFbeta signaling pathway, is a master regulator of ADAM12 expression in response to TGFbeta1 stimulation. Overexpression of SnoN in NIH3T3 cells reduces the magnitude of ADAM12 induction by TGFbeta1 treatment. Down-regulation of SnoN expression by short hairpin RNA enhances TGFbeta1-induced expression of ADAM12. In a panel of TGFbeta1-responsive cancer cell lines with high expression of SnoN, induction of ADAM12 by TGFbeta1 is significantly impaired, suggesting that the endogenous SnoN plays a role in regulating ADAM12 expression in response to TGFbeta1. Identification of SnoN as a repressor of the ADAM12 gene should contribute to advances in the studies on the role of ADAM12 in tumor progression and in the development of other pathologies.