The metalloproteinase ADAM-12 regulates bronchial epithelial cell proliferation and apoptosis

The emerging roles of lysine-specific demethylase 4A in cancer: Implications in tumorigenesis and therapeutic opportunities

Lysine-specific demethylase 4 A (KDM4A, also named JMJD2A, KIA0677, or JHDM3A) is a demethylase that can remove methyl groups from histones H3K9me2/3, H3K36me2/3, and H1.4K26me2/me3. Accumulating evidence suggests that KDM4A is not only involved in body homeostasis (such as cell proliferation, migration and differentiation, and tissue development) but also associated with multiple human diseases, especially cancers. Recently, an increasing number of studies have shown that pharmacological inhibition of KDM4A significantly attenuates tumor progression in vitro and in vivo in a range of solid tumors and acute myeloid leukemia. Although there are several reviews on the roles of the KDM4 subfamily in cancer development and therapy, all of them only briefly introduce the roles of KDM4A in cancer without systematically summarizing the specific mechanisms of KDM4A in various physiological and pathological processes, especially in tumorigenesis, which greatly limits advances in the understanding of the roles of KDM4A in a variety of cancers, discovering targeted selective KDM4A inhibitors, and exploring the adaptive profiles of KDM4A antagonists. Herein, we present the structure and functions of KDM4A, simply outline the functions of KDM4A in homeostasis and non-cancer diseases, summarize the role of KDM4A and its distinct target genes in the development of a variety of cancers, systematically classify KDM4A inhibitors, summarize the difficulties encountered in the research of KDM4A and the discovery of related drugs, and provide the corresponding solutions, which would contribute to understanding the recent research trends on KDM4A and advancing the progression of KDM4A as a drug target in cancer therapy.

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.

Identification and Exploration of Novel Macrophage M2-Related Biomarkers and Potential Therapeutic Agents in Endometriosis

Endometriosis (EM) is a chronic neuroinflammatory disorder that is associated with pain and infertility that affects ∼10% of reproductive-age women. The pathophysiology and etiology of EM remain poorly understood, and diagnostic delays are common. Exploration of the underlying molecular mechanism, as well as novel diagnostic biomarkers and therapeutic targets, is urgently needed. Inflammation is known to play a key role in the development of lesions, which are a defining feature of the disorder. In our research, the CIBERSORT and WGCNA algorithms were used to establish a weighted gene co-expression network and to identify macrophage-related hub genes using data downloaded from the GEO database (GSE11691, 7305). The analysis identified 1,157 differentially expressed genes (DEGs) in EM lesions, of which five were identified as being related to M2 macrophages and were validated as differentially expressed by qRT-PCR and immunohistochemistry (IHC). Of these putative novel biomarker genes, bridging integrator 2 (BIN2), chemokine receptor 5 (CCR5), and macrophage mannose receptor 1 (MRC1) were upregulated, while spleen tyrosine kinase (SYK) and metalloproteinase 12 (ADAM12) were downregulated in ectopic endometria vs. normal endometria. Meanwhile, 23 potentially therapeutic small molecules for EM were obtained from the cMAP database, among which topiramate, isoflupredone, adiphenine, dexverapamil, MS-275, and celastrol were the top six molecules with the highest absolute enrichment values. This is our first attempt to use the CIBERSORT and WGCNA algorithms for the identification of novel Mϕ2 macrophage-related biomarkers of EM. Our findings provide novel insights into the impact of immune cells on the etiology of EM; nevertheless, further investigation of these key genes and therapeutic drugs is needed to validate their effects on EM.

Transcriptional analysis of cleft palate in TGFβ3 mutant mice

Cleft palate (CP) is one of the most common craniofacial birth defects, impacting about 1 in 800 births in the USA. Tgf-β3 plays a critical role in regulating murine palate development, and Tgf-β3 null mutants develop cleft palate with 100% penetrance. In this study, we compared global palatal transcriptomes of wild type (WT) and Tgf-β3 −/− homozygous (HM) mouse embryos at the crucial palatogenesis stages of E14.5, and E16.5, using RNA-seq data. We found 1,809 and 2,127 differentially expressed genes at E16.5 vs. E14.5 in the WT and HM groups, respectively (adjusted p < 0.05; |fold change|> 2.0). We focused on the genes that were uniquely up/downregulated in WT or HM at E16.5 vs. E14.5 to identify genes associated with CP. Systems biology analysis relating to cell behaviors and function of WT and HM specific genes identified functional non-Smad pathways and preference of apoptosis to epithelial-mesenchymal transition. We identified 24 HM specific and 11 WT specific genes that are CP-related and/or involved in Tgf-β3 signaling. We validated the expression of 29 of the 35 genes using qRT-PCR and the trend of mRNA expression is similar to that of RNA-seq data . Our results enrich our understanding of genes associated with CP that are directly or indirectly regulated via TGF-β.

ADAM12 induces EMT and promotes cell migration, invasion and proliferation in pituitary adenomas via EGFR/ERK signaling pathway

Pituitary adenomas are the second most common primary brain tumor with invasive properties. We have previously identified that ADAM12 (a disintegrin and metalloprotease 12) overexpression is associated with the tumor invasion of pituitary adenomas, however, the underlying mechanism remains unknown. This study aims to elucidate the mechanistic role of ADAM12 in regulating the tumor invasion of pituitary adenomas. In this study, we first showed that ADAM12 expression was concomitant with epithelial to mesenchymal transition (EMT) process in clinical specimens of human pituitary adenomas. Further functional studies showed that ADAM12 silencing in pituitary adenoma cells significantly inhibited the EMT process and suppressed cell migration, invasion and proliferation without influencing cell apoptosis. Mechanistically, ADAM12 silencing significantly reduced ectodomain shedding of epidermal growth factor receptor (EGFR) ligands and attenuated the EGFR/ERK signaling pathway. Blocking of EGFR signaling resulted in EMT suppression similar to silencing of ADAM12 and reduced cell migration, invasion and proliferation, while EGFR activation abolished the suppression on EMT, proliferation, migration and invasion induced by ADAM12 silencing. Moreover, ADAM12 silencing significantly impaired tumorigenesis and EMT of pituitary adenoma cells in vivo. Taken together, our study provide crucial evidence that ADAM12 induces EMT and promotes cell migration, invasion and proliferation in pituitary adenomas via EGFR/ERK signaling pathway. These finds strongly suggest that ADAM12 might serve as a novel valuable therapeutic target for pituitary adenomas.

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.

Methyl Protodioscin, a Steroidal Saponin, Inhibits Neointima Formation in Vitro and in Vivo

Restenosis (or neointimal hyperplasia) remains a clinical limitation of percutaneous coronary angioplasty. Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are known to be involved in the development of restenosis. The present study aimed to investigate the ability and molecular mechanisms of methyl protodioscin (1), a steroidal saponin isolated from the root of Dioscorea nipponica, to inhibit neointimal formation. Our study demonstrated that 1 markedly inhibited the growth and migration of VSMCs (A7r5 cells). A cytometric analysis suggested that 1 induced growth inhibition by arresting VSMCs at the G1 phase of the cell cycle. A rat carotid artery balloon injury model indicated that neointima formation of the balloon-injured vessel was markedly reduced after extravascular administration of 1. Compound 1 decreased the expression levels of ADAM15 (a disintegrin and metalloprotease 15) and its downstream signaling pathways in the VSMCs. Moreover, the expressions and activities of matrix metalloproteinases (MMP-2 and MMP-9) were also suppressed by 1 in a concentration-dependent manner. Additionally, the molecular mechanisms appear to be mediated, in part, through the downregulation of ADAM15, FAK, ERK, and PI3K/Akt.

ADAM33 and ADAM12 genetic polymorphisms and their expression in Egyptian children with asthma

BACKGROUND

The ADAM family is involved in some pathologic processes, such as inflammation and asthma.

OBJECTIVES

To assess the association between ADAM33 and ADAM12 single-nucleotide polymorphisms (SNPs) with asthma risk and severity and to investigate the effect of ADAM33 and ADAM12 polymorphisms on expression of these proteases in sputum.

METHODS

Two SNPs of the ADAM33 gene, F+1 (rs511898) G/A and ST+4 (rs44707) A/C, and 2 SNPs of the ADAM12 gene, rs3740199 and rs1871054, were analyzed in 400 asthma cases and 200 controls aged 3 to 14 years using the polymerase chain reaction-restriction fragment length polymorphism method. Messenger RNA expression profile of ADAM33 and ADAM12 proteases in sputum from studied groups was determined by reverse transcription polymerase chain reaction.

RESULTS

ADAM33 F+1 homozygous mutant genotype (AA) and ST+4 heterozygous and homozygous mutant genotype (AC and CC) and mutant alleles of both polymorphisms were significantly associated with asthma risk and severity in moderate and severe subgroups. Patients with the ADAM12 (rs3740199) CC genotype were at increased risk for moderate and severe asthma. Messenger RNA levels of ADAM12 were significantly increased in asthmatic children compared with controls, whereas we were not able to detect the expression of ADAM33 in the sputum of the groups studied. The ADAM12 expression was significantly higher in homozygous CC (variant type) compared with homozygous GG (wild type) of both ADAM12 rs3740199 and rs1871054 in the asthmatic group.

CONCLUSION

Our analysis suggests a likely role for ADAM33 and ADAM12 in the development of asthma in Egyptian children. Furthermore, ADAM12 polymorphisms may affect ADAM12 expression in asthma.

Targeting autocrine HB-EGF signaling with specific ADAM12 inhibition using recombinant ADAM12 prodomain

Dysregulation of ErbB-family signaling underlies numerous pathologies and has been therapeutically targeted through inhibiting ErbB-receptors themselves or their cognate ligands. For the latter, “decoy” antibodies have been developed to sequester ligands including heparin-binding epidermal growth factor (HB-EGF); however, demonstrating sufficient efficacy has been difficult. Here, we hypothesized that this strategy depends on properties such as ligand-receptor binding affinity, which varies widely across the known ErbB-family ligands. Guided by computational modeling, we found that high-affinity ligands such as HB-EGF are more difficult to target with decoy antibodies compared to low-affinity ligands such as amphiregulin (AREG). To address this issue, we developed an alternative method for inhibiting HB-EGF activity by targeting its cleavage from the cell surface. In a model of the invasive disease endometriosis, we identified A Disintegrin and Metalloproteinase 12 (ADAM12) as a protease implicated in HB-EGF shedding. We designed a specific inhibitor of ADAM12 based on its recombinant prodomain (PA12), which selectively inhibits ADAM12 but not ADAM10 or ADAM17. In endometriotic cells, PA12 significantly reduced HB-EGF shedding and resultant cellular migration. Overall, specific inhibition of ligand shedding represents a possible alternative to decoy antibodies, especially for ligands such as HB-EGF that exhibit high binding affinity and localized signaling.

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.

Silencing ADAM10 inhibits the in vitro and in vivo growth of hepatocellular carcinoma cancer cells

A disintegrin and metalloprotease 10 (ADAM10) is a transmembrane protein associated with metastasis in a number of types of cancer. Little is known, however, regarding the role of ADAM10 in hepatocellular carcinoma (HCC). The aim of the present study was to evaluate whether downregulation of ADAM10 effects HCC cell proliferation, cell cycle, cell migration and cell invasion. A recombinant small hairpin RNA expression vector carrying ADAM10 was constructed and then transfected into the HepG2 human HCC cell line. In vitro cell proliferation, cell cycle, cell migration and cell invasion, and in vivo tumor growth were determined following the downregulation of ADAM10 by RNA interference. The results revealed that downregulation of ADAM10 expression in HepG2 tumor cells using the RNA silencing approach significantly suppressed cell proliferation, cell migration and cell invasion in vitro, and tumor growth in vivo. Furthermore, ADAM10 silencing was able to significantly reduce constitutive phosphorylation of phosphoinositide 3-kinase (PI3K) and Akt, which implies that ADAM10 is, at least partially, involved in the activation of the PI3K/Akt signaling pathway. These results suggest that ADAM10 is important in regulating the proliferation and metastasis of HCC. Thus, ADAM10 is a promising therapeutic target for the prevention of tumor metastases in HCC.

ADAM17 mediates OSCC development in an orthotopic murine model

BACKGROUND

ADAM17 is one of the main sheddases of the cells and it is responsible for the cleavage and the release of ectodomains of important signaling molecules, such as EGFR ligands. Despite the known crosstalk between ADAM17 and EGFR, which has been considered a promising targeted therapy in oral squamous cell carcinoma (OSCC), the role of ADAM17 in OSCC development is not clear.

METHOD

In this study the effect of overexpressing ADAM17 in cell migration, viability, adhesion and proliferation was comprehensively appraised in vitro. In addition, the tumor size, tumor proliferative activity, tumor collagenase activity and MS-based proteomics of tumor tissues have been evaluated by injecting tumorigenic squamous carcinoma cells (SCC-9) overexpressing ADAM17 in immunodeficient mice.

RESULTS

The proteomic analysis has effectively identified a total of 2,194 proteins in control and tumor tissues. Among these, 110 proteins have been down-regulated and 90 have been up-regulated in tumor tissues. Biological network analysis has uncovered that overexpression of ADAM17 regulates Erk pathway in OSCC and further indicates proteins regulated by the overexpression of ADAM17 in the respective pathway. These results are also supported by the evidences of higher viability, migration, adhesion and proliferation in SCC-9 or A431 cells in vitro along with the increase of tumor size and proliferative activity and higher tissue collagenase activity as an outcome of ADAM17 overexpression.

CONCLUSION

These findings contribute to understand the role of ADAM17 in oral cancer development and as a potential therapeutic target in oral cancer. In addition, our study also provides the basis for the development of novel and refined OSCC-targeting approaches.

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.

Curcumin-cyclodextrin complexes potentiate gemcitabine effects in an orthotopic mouse model of lung cancer

Background:

Overall clinical outcome for advanced lung cancer remains very disappointing despite recent advances in treatment. Curcumin has been reported as potentially active against cancer.

Methods:

Owing to poor curcumin solubility, we have used cyclodextrins (CD) as an excipient allowing a considerable increase of aqueous solubility and bioavailability of curcumin. The effects of solubilised curcumin have been evaluated in cell cultures as well as in an in vivo orthotopic lung tumour mouse model.

Results:

Cell proliferation was reduced while apoptosis rates were increased when lung epithelial tumour cells were cultured in the presence of curcumin–CD complexes. For in vivo experiments, cells were grafted into lungs of C57Bl/6 mice treated by an oral administration of a non-soluble form of curcumin, CDs alone or curcumin–CD complexes, combined or not with gemcitabine. The size of orthotopically implanted lung tumours was reduced upon curcumin complex administration as compared with treatments with placebo or non-solubilised curcumin. Moreover, curcumin potentiated the gemcitabine-mediated antitumour effects.

Conclusion:

Our data demonstrate that curcumin, when given orally in a CD-solubilised form, reduces lung tumour size in vivo. In vitro experiments show impaired tumour cell proliferation and increased cell apoptosis. Moreover, our data underline a potential additive effect of curcumin with gemcitabine thus providing an efficient therapeutic option for antilung cancer therapy.

ADAM10 overexpression confers resistance to doxorubicin-induced apoptosis in hepatocellular carcinoma

Chemoresistance represents a major obstacle to successful treatment of hepatocellular carcinoma (HCC). A disintegrin and metalloproteinase 10 (ADAM10) is known to be frequently upregulated in many cancers. We aimed to determine the biological function of ADAM10 in the chemoresistance of HCC cells. Overexpression of ADAM10 in three HCC cell lines (HepG2, Hep3B, and Huh7) conferred protection against doxorubicin-induced apoptosis, as determined by Annexin V staining. Western blot analysis revealed that ADAM10-overexpressing cells had a significantly lower amount of cleaved caspase-3 and an elevated expression of myeloid cell leukemia-1 (Mcl-1), a prosurvival member of the Bcl-2 family. Conversely, RNA interference-mediated silencing of endogenous ADAM10 potentiated doxorubicin-induced apoptosis in HepG2 and Hep3B cells, which was coupled with increased cleavage of caspase-3 and decreased expression of Mcl-1. Ectopic expression of ADAM10 resulted in a marked increase in the phosphorylation of phosphatidylinositol 3-kinase (PI3-K) and Akt. Most interestingly, the pretreatment with the PI3-K inhibitor LY294002 significantly enhanced doxorubicin-induced apoptosis and diminished the Mcl-1 expression in ADAM10-overexpressing Huh7 cells. Our data provide evidence that ADAM10 plays an important role in modulating the chemosensitivity of HCC cells, which, at least partially, involves the activation of the PI3-K/Akt pathway. ADAM10 may be a promising target for the improvement of chemotherapeutic efficacy in HCC.

Histamine may induce airway remodeling through release of epidermal growth factor receptor ligands from bronchial epithelial cells

Asthma is a chronic inflammatory disease that is associated with airway remodeling, including hyperplasia of airway epithelial cells and airway smooth muscle cells, and goblet cell differentiation. We wished to address the potential role of histamine, a key biogenic amine involved in allergic reactions, in airway remodeling through the epidermal growth factor receptor (EGFR) pathway. Here, we demonstrate that histamine releases 2 EGFR ligands, amphiregulin and heparin-binding epidermal growth factor-like growth factor (HB-EGF), from airway epithelial cells. Amphiregulin and HB-EGF were expressed in airway epithelium of patients with asthma. Histamine up-regulated their mRNA expression (amphiregulin 3.2-fold, P<0.001; HB-EGF 2.3-fold, P<0.05) and triggered their release (amphiregulin EC(50) 0.50 μM, 31.2 ± 2.7 pg/ml with 10 μM histamine, P<0.01; HB-EGF EC(50) 0.54 μM, 78.5 ± 1.8 pg/ml with 10 μM histamine, P<0.001) compared to vehicle control (amphiregulin 19.3 ± 0.9 pg/ml; HB-EGF 60.2 ± 1.0 pg/ml), in airway epithelial cells. Histamine increased EGFR phosphorylation (2.1-fold by Western blot analysis) and induced goblet cell differentiation (CLCA1 up-regulation by real-time qPCR) in normal human bronchial epithelial (NHBE) cells. Moreover, amphiregulin and HB-EGF caused proliferation and migration of both NHBE cells and human airway smooth muscle cells. These results suggest that histamine may induce airway remodeling via the epithelial-derived EGFR ligands amphiregulin and HB-EGF.

Molecular characterization and expression analysis of ADAM12 during chicken embryonic development

ADAM12 is a member of the disintegrin and metalloprotease (ADAM) family of molecules, which consist of multiple domains. ADAM12 is involved in different physiological and pathological processes. In the present study, full-length sequences of two chicken ADAM12 isoforms were cloned and identified by reverse transcription-polymerase chain reaction (RT-PCR), rapid amplification of cDNA ends methods and bioinformatics analysis. The long isoform consists of all domains characteristic for ADAMs and is strongly expressed in different tissues, whereas the short isoform lacks large parts of the metalloprotease and disintegrin domains and is only expressed weakly. Results from semi-quantitative RT-PCR show that the complete ADAM12 is stably expressed throughout chicken embryonic development, while the short isoform is only regionally detectable in the lung and brain. Results from in situ hybridization show that chicken ADAM12 is expressed exclusively in tissues and organs derived from the neural tube, the neural crest or the mesoderm, with a highly regulated spatiotemporal expression pattern. Our data confirm and extend studies of ADAM12 in other species, and suggest that ADAM12 may play a role in the development of several organs, including the formation of feather buds.

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.

Aberrant expression of disintegrin-metalloprotease proteins in the formation and progression of uterine cervical cancer

OBJECTIVE

Dysregulated expression of disintegrin-metalloprotease proteins [a disintegrin and metalloproteases (ADAMs) and ADAMs with thrombospondin motif (ADAMTSs)] has been reported in many types of cancers and is believed to play an important role in cancer formation and metastasis. However, little is known about the expression of ADAMs and ADAMTSs in the development of human cervical cancer.

METHODS

Reverse transcriptase polymerase chain reaction and immunoblotting were performed to assess the expression of several disintegrin-metalloproteases and tissue inhibitors of metalloproteinases (TIMPs) in squamous-type cervical cancer cells and oncogenically modified keratinocytes (immortalized human cervical keratinocytes transduced with human papilloma virus-16 E6/E7 proteins with or without oncogenes). Immunohistochemistry of ADAM-9, ADAM-10 and TIMP-3 was performed on 31 primary human cervical tissue specimens of preinvasive and invasive cervical carcinoma.

RESULTS

mRNA levels of ADAM-9, ADAM-10, ADAM-12, TIMP-2 and TIMP-3 were upregulated as cervical cells progressed from dysplastic to malignant lesions compared to normal cervical cells. These results were corroborated at the protein level by Western blot analysis and immunohistochemistry.

CONCLUSION

The expression of disintegrin-metalloproteases and their endogenous regulators was dysregulated during cervical carcinogenesis. The aberrant expression of ADAMs might contribute to the pathogenesis of cervical cancer formation and progression.

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.

Transforming growth factor-beta1-mediated activation of NF-kappaB contributes to enhanced ADAM-12 expression in mammary carcinoma cells

A disintegrin and metalloproteinase-12 (ADAM-12), a member of multifunctional family of proteins, is upregulated in many cancers, including breast, lung, liver, prostate, gastric, and bladder. The multidomain structure, composed of a prodomain, a metalloproteinase, disintegrin-like, epidermal growth factor-like, cysteine-rich and transmembrane domains, and a cytoplasmic tail, allows ADAM-12 to promote matrix degradation, cell-cell adhesion, and intracellular signaling capacities and thereby to play a critical role in cancer growth and metastasis. Despite ample evidence linking increased ADAM-12 expression with cancer, the mechanisms controlling its upregulation are still unknown. In the present study, transforming growth factor-β1 (TGF-β1) is shown to increase ADAM-12 mRNA expression in MDA-MB-231 breast carcinoma cells. We have identified a promoter element responsible for TGF-β1-mediated ADAM-12 induction. We show interaction of NF-κB with ADAM-12 promoter and that high level of NF-κB activity in breast carcinoma cells results in the upregulation of ADAM-12 expression. Site-directed mutagenesis of the NF-κB element in ADAM-12 promoter and inhibition of NF-κB activity by Bay-11-7085 and MG-132 significantly reduced TGF-β1-mediated increase of ADAM-12 promoter-driven gene expression. Transfection of cells with a dominant-negative mutant form of IκBα (IκBαΔN), which inhibits activation of NF-κB, significantly reduced transcription from ADAM-12 promoter-reporter in TGF-β1-stimulated MDA-MB-231 cancer cells. In correlation, overexpression of NF-κB induced ADAM-12 expression in a dose-dependent manner. DNA-binding and ChIP assays indicated that p65 subunit of NF-κB binds to ADAM-12 promoter. Together, our study identified a cellular mechanism for induction of ADAM-12, which involves NF-κB and its activation by TGF-β1.

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

A disintegrin and metalloproteinase 9 (ADAM9) is a type I transmembrane protein that has been associated with cancer development and metastases. Here, we show that ADAM9 is highly expressed in metastatic cancer tissues and in an adenoid cystic carcinoma cell line with a high metastatic potential. Using RNA interference for gene silencing, we show that ADAM9 is essential for in vitro cancer cell proliferation and invasion as well as in vivo cancer metastasis in an experimental murine model of lung metastases. These data indicate that ADAM9 is potentially an important new therapeutic target for the prevention of tumor metastases in adenoid cystic carcinoma.

Intestinal phenotype in mice overexpressing a heparin-binding EGF-like growth factor transgene in enterocytes

PRIMARY OBJECTIVE

Heparin-binding EGF-like growth factor (HB-EGF) protects the intestine from damage in animals. Future clinical trials of HB-EGF may involve administration of repeated doses of HB-EGF. Since HB-EGF activates EGF receptors which have been implicated in tumor development, we examined the effects of HB-EGF overexpression in the intestine.

RESEARCH DESIGN

We generated transgenic (TG) mice in which the human HB-EGF gene is driven by the villin promoter to overexpress HB-EGF along the crypt-villous axis from the duodenum to the colon.

RESULTS

HB-EGF TG mice have increased enterocyte proliferation balanced by increased enterocyte apoptosis. Despite prolonged overexpression of HB-EGF, no evidence of intestinal hyperplasia or tumor formation occurs. Although HB-EGF TG mice have no significant phenotypic alterations under basal conditions, they have increased resistance to intestinal injury.

CONCLUSIONS

Prolonged intestinal HB-EGF overexpression results in no significant phenotypic alterations under basal conditions, but confers protection against intestinal injury.

Role of ADAM and ADAMTS metalloproteinases in airway diseases

Lungs are exposed to the outside environment and therefore to toxic and infectious agents or allergens. This may lead to permanent activation of innate immune response elements. A Disintegrin And Metalloproteinases (ADAMs) and ADAMs with Thrombospondin motifs (ADAMTS) are proteinases closely related to Matrix Metalloproteinases (MMPs). These multifaceted molecules bear metalloproteinase and disintegrin domains endowing them with features of both proteinases and adhesion molecules. Proteinases of the ADAM family are associated to various physiological and pathological processes and display a wide spectrum of biological effects encompassing cell fusion, cell adhesion, "shedding process", cleavage of various substrates from the extracellular matrix, growth factors or cytokines... This review will focus on the putative roles of ADAM/ADAMTS proteinases in airway diseases such as asthma and COPD.

Role of A disintegrin and metalloprotease-12 in neutrophil recruitment induced by airway epithelium

Among proteases, metalloproteases are implicated in tissue remodeling, as shown in numerous diseases including allergy. ADAMs (A Disintegrin And Metalloprotease) metalloproteases are implicated in physiologic processes such as cytokine and growth factor shedding, cell migration, adhesion, or repulsion. Our aim was to measure ADAM-12 expression in airway epithelium and to define its role during the allergic response. To raise this question, we analyzed the ADAM-12 expression ex vivo after allergen exposure in patients with allergic rhinitis and in vitro in cultured primary human airway epithelial cells (AEC). Clones of BEAS-2B cells transfected with the full-length form of ADAM-12 were generated to study the consequences of ADAM-12 up-regulation on AEC function. After allergen challenge, a strong increase of ADAM-12 expression was observed in airway epithelium from patients with allergic rhinitis but not from control subjects. In contrast with the other HB-epidermal growth factor sheddases, ADAM-10 and -17, TNF-alpha in vitro increased the expression of ADAM-12 by AEC, an effect amplified by IL-4 and IL-13. Up-regulation of ADAM-12 in AEC increased the expression of alpha3 and alpha4 integrins and to the modulation of cell migration on fibronectin but not on collagen. Moreover, overexpression of ADAM-12 in BEAS-2B enhanced the secretion of CXCL1 and CXCL8 and their capacity to recruit neutrophils. CD47 was strongly decreased by ADAM-12 overexpression, a process associated with a reduced adhesion of neutrophils. These effects were mainly dependent on epidermal growth factor receptor activation. In summary, ADAM-12 is produced during allergic reaction by AEC and might increase neutrophil recruitment within airway mucosa.