Expression of a disintegrin and metalloprotease (ADAM and ADAMTS) enzymes in human non-small-cell lung carcinomas (NSCLC)

Expression of ADAMs ("a disintegrin and metalloprotease") in the human lung

In view of the associations of "a disintegrin and metalloprotease" (ADAM) with respiratory diseases, we assessed the expression of various ADAMs in human lung tissue. Lung tissue was obtained from nine individuals who underwent surgery for lung cancer or underwent lung transplantation for emphysema. Also, 16HBE 14o- (human bronchial epithelial) and A549 (alveolar type II epithelium-like) cell lines were used. Immunohistochemistry was performed with antibodies recognizing different ADAM domains. The ADAMs were typically distributed over the bronchial epithelium. ADAM8 and ADAM10 were expressed diffusely in all layers of the epithelium. ADAM9, ADAM17, and ADAM19 were predominantly expressed in the apical part of the epithelium, and ADAM33 was predominantly and strongly expressed in basal epithelial cells. In smooth muscle, ADAM19 and ADAM17 were strongly expressed, as was ADAM33, though this expression was weaker. ADAM33 was strongly expressed in vascular endothelium. All ADAMs were generally expressed in inflammatory cells. The typical distribution of ADAMs in the lung, especially in the epithelium, is interesting and suggests a localized function. As most ADAMs are involved in release of (pro-) inflammatory mediators and growth factors, they may play an important role in the first line of defense and in initiation of repair events in the airways.

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

OBJECTIVES

The ADAMs (a disintegrin and metalloproteinase) enzymes compose a family of membrane-bound proteins characterized by their multi-domain structure and ADAM-12 expression is elevated in human non-small cell lung cancers. The aim of this study was to investigate the roles played by ADAM-12 in critical steps of bronchial cell transformation during carcinogenesis.

MATERIALS AND METHODS

To assess the role of ADAM-12 in tumorigenicity, BEAS-2B cells were transfected with a plasmid encoding human full-length ADAM-12 cDNA, and then the effects of ADAM-12 overexpression on cell behaviour were explored. Treatment of clones with heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) neutralizing antibodies as well as an EGFR inhibitor allowed the dissection of mechanisms regulating cell proliferation and apoptosis.

RESULTS

Overexpression of ADAM-12 in BEAS-2B cells promoted cell proliferation. ADAM-12 overexpressing clones produced higher quantities of HB-EGF in their culture medium which may rely on membrane-bound HB-EGF shedding by ADAM-12. Targeting HB-EGF activity with a neutralizing antibody abrogated enhanced cell proliferation in the ADAM-12 overexpressing clones. In sharp contrast, targeting of amphiregulin, EGF or transforming growth factor-alpha failed to influence cell proliferation; moreover, ADAM-12 transfectants were resistant to etoposide-induced apoptosis and the use of a neutralizing antibody against HB-EGF activity restored rates of apoptosis to be similar to controls.

CONCLUSIONS

ADAM-12 contributes to enhancing HB-EGF shedding from plasma membranes leading to increased cell proliferation and reduced apoptosis in this bronchial epithelial cell line.

ADAMTS-1 metalloproteinase promotes tumor development through the induction of a stromal reaction in vivo

ADAMTS-1 (a disintegrin and metalloproteinase with thrombospondin motifs), the first described member of the ADAMTS family, is differentially expressed in various tumors. However, its exact role in tumor development and progression is still unclear. The aim of this study was to investigate the effects of ADAMTS-1 transfection in a bronchial epithelial tumor cell line (BZR) and its potential to modulate tumor development. ADAMTS-1 overexpression did not affect in vitro cell properties such as (a) proliferation in two-dimensional culture, (b) proliferation in three-dimensional culture, (c) anchorage-independent growth in soft agar, (d) cell migration and invasion in modified Boyden chamber assay, (e) angiogenesis in the aortic ring assay, and (f) cell apoptosis. In contrast, ADAMTS-1 stable transfection in BZR cells accelerated the in vivo tumor growth after s.c. injection into severe combined immunodeficient mice. It also promoted a stromal reaction characterized by myofibroblast infiltration and excessive matrix deposition. These features are, however, not observed in tumors derived from cells overexpressing a catalytically inactive mutant of ADAMTS-1. Conditioned media from ADAMTS-1-overexpressing cells display a potent chemotactic activity toward fibroblasts. ADAMTS-1 overexpression in tumors was associated with increased production of matrix metalloproteinase-13, fibronectin, transforming growth factor beta (TGF-beta), and interleukin-1beta (IL-1beta). Neutralizing antibodies against TGF-beta and IL-1beta blocked the chemotactic effect of medium conditioned by ADAMTS-1-expressing cells on fibroblasts, showing the contribution of these factors in ADAMTS-1-induced stromal reaction. In conclusion, we propose a new paradigm for catalytically active ADAMTS-1 contribution to tumor development, which consists of the recruitment of fibroblasts involved in tumor growth and tumor-associated stroma remodeling.

HDAC inhibition upregulates the expression of angiostatic ADAMTS1

HDAC inhibitors are promising anticancer agents that induce cell cycle arrest and apoptosis. However, the role of HDACs in cancer progression, such as angiogenesis and metastasis, remains largely unexplored. Among various HDAC inhibitors, we demonstrate that TSA and SAHA upregulated the expression of angiostatic ADAMTS1 in A549 cells. HDAC6 inhibitor tubacin, and knockdown of HDAC6, also lead to ADAMTS1 upregulation. By reporter, DAPA, and ChIP assays, the proximal GC boxes were demonstrated to be essential for ADAMTS1 induction. Decreased binding of SP1 and HDAC6 to the ADAMTS1 promoter after TSA treatment was also seen. These data suggest the involvement of HDAC6 and SP1 in the HDACi-induced expression of angiostatic ADAMTS1.

Cellular roles of ADAM12 in health and disease

ADAM12 belongs to the large family of ADAMs (a disintegrin and metalloproteases) and possesses extracellular metalloprotease and cell-binding functions, as well as intracellular signaling capacities. Interest in ADAM12 has increased recently because its expression is related to tumor progression and it is a potential biomarker for breast cancer. It is therefore important to understand ADAM12's functions. Many cellular roles for ADAM12 have been suggested. It is an active metalloprotease, and has been implicated in insulin-like growth factor (IGF) receptor signaling, through cleavage of IGF-binding proteins, and in epidermal growth factor receptor (EGFR) pathways, via ectodomain shedding of membrane-tethered EGFR ligands. These proteolytic events may regulate diverse cellular responses, such as altered cell differentiation, proliferation, migration, and invasion. ADAM12 may also regulate cell-cell and cell-extracellular matrix contacts through interactions with cell surface receptors - integrins and syndecans - potentially influencing the actin cytoskeleton. Moreover, ADAM12 interacts with several cytoplasmic signaling and adaptor molecules through its intracellular domain, thereby directly transmitting signals to or from the cell interior. These ADAM12-mediated cellular effects appear to be critical events in both biological and pathological processes. This review presents current knowledge on ADAM12 functions gained from in vitro and in vivo observations, describes ADAM12's role in both normal physiology and pathology, particularly in cancer, and discusses important areas for future investigation.

Altered expression of genes regulating angiogenesis in experimental androgen-independent prostate cancer

BACKGROUND

The aim of this study was to investigate how the expression of genes regulating angiogenesis is altered when prostate cancer cells progress into androgen-independency.

METHODS

A gene array specific for angiogenesis was used to compare the human prostate cancer cell line LNCaP (androgen-dependent) with its more angiogenic and tumorigenic subline LNCaP-19 (androgen-independent). Results were verified with real-time RT-PCR, and further investigations were focused on the angiogenesis inhibitor a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1). Expression of ADAMTS1 was investigated in vitro as well as in subcutaneous tumors with real-time RT-PCR and Western blotting. Microvessel density (MVD), versican proteolysis and protein levels of TIMP-2 and TIMP-3, known as ADAMTS1 inhibitors, were also analyzed in tumor xenografts.

RESULTS

The gene array revealed decreased expression of ADAMTS1, ephrin-A5, fibronectin 1, and neuropilin 1 in LNCaP-19 compared to LNCaP, while expression of midkine and VEGF were increased. Further studies showed that mRNA and protein levels of ADAMTS1 were significantly lower in LNCaP-19 compared to LNCaP, both in vitro and in subcutaneous tumors. The amount of ADAMTS1 correlated negatively with MVD, but no relation was found between ADAMTS1 and versican proteolysis.

CONCLUSIONS

Expression of several genes associated with angiogenesis was altered during transition into androgen-independency. Among these, a significant decrease was found for ADAMTS1, whose expression inversely correlated with MVD. Its role in progression of prostate cancer needs further investigation, but this inhibitor of angiogenesis could be an interesting candidate for future anti-angiogenic therapy.

Nuclear translocation of ADAM-10 contributes to the pathogenesis and progression of human prostate cancer

A disintegrin and metalloproteases (ADAM) are cell membrane-anchored proteins with potential implications for the metastasis of human cancer cells via cell adhesion and protease activities. In prostate cancer (PC), the ADAM-10 protein showed a nuclear localization whereas in benign prostate hypertrophy (BPH) it was predominantly bound to the cell membrane. We hypothesized that the pathogenesis and progression of PC are attributable to the nuclear translocation of ADAM-10. Immunoblotting revealed that after 5alpha-dihydrotestosterone treatment, a 60-kDa active form of ADAM-10 was increased in the nuclear fraction but decreased in the cell membrane and cytoplasmic fractions of human androgen-dependent PC cells. Immunocytochemistry revealed that after 5alpha-dihydrotestosterone treatment, the ADAM-10 protein was translocated from the cell membrane to the nucleus. Coimmunoprecipitation of androgen receptor and ADAM-10 was detected in the nuclear fraction but not in the cell membrane and cytoplasmic fractions. Immunohistochemical study of 64 PC and 20 BPH samples showed that the intensity of ADAM-10 staining was significantly higher in the nuclei of PC cells than in the nuclei of BPH cells (P < 0.0001). It was also significantly lower in the cell membrane of PC cells than in the cell membrane of BPH cells (P = 0.0017). Nuclear staining intensity was significantly correlated with the clinical T-factor (P = 0.004), the Gleason score (P < 0.0001) and preoperative prostate-specific antigen levels (P = 0.0061). ADAM-10 small interfering RNA transfectants showed a significant decrease in cell growth compared to the controls. Our results suggest that in human PC, the nuclear translocation of ADAM-10 coupled with the androgen receptor is involved in tumor growth and progression.

Emerging roles of proteases in tumour suppression

Proteases have long been associated with cancer progression because of their ability to degrade extracellular matrices, which facilitates invasion and metastasis. However, recent studies have shown that these enzymes target a diversity of substrates and favour all steps of tumour evolution. Unexpectedly, the post-trial studies have also revealed proteases with tumour-suppressive effects. These effects are associated with more than 30 different enzymes that belong to three distinct protease classes. What are the clinical implications of these findings?

Emerging roles of ADAM and ADAMTS metalloproteinases in cancer

A disintegrin and metalloproteinases (ADAMs) are a recently discovered family of proteins that share the metalloproteinase domain with matrix metalloproteinases (MMPs). Among this family, structural features distinguish the membrane-anchored ADAMs and the secreted ADAMs with thrombospondin motifs referred to as ADAMTSs. By acting on a large panel of membrane-associated and extracellular substrates, they control several cell functions such as adhesion, fusion, migration and proliferation. The current review addresses the contribution of these proteinases in the positive and negative regulation of cancer progression as mainly mediated by the regulation of growth factor activities and integrin functions.

Quantitative real-time reverse transcription PCR study of the expression of vascular endothelial growth factor (VEGF) splice variants and VEGF receptors (VEGFR-1 and VEGFR-2) in non small cell lung cancer

BACKGROUND

Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis and its expression is increased in non-small cell lung cancer (NSCLC). We aimed to determine the expression pattern of VEGF splice variants in NSCLC and its correlation with the clinicopathological characteristics of tumors.

METHODS

We used real-time reverse transcription PCR to quantify the mRNA expression of total VEGF, 4 VEGF splice variants (VEGF(121), VEGF(165), VEGF(183), and VEGF(189)), and 2 VEGF receptors (VEGFR-1 and VEGFR-2) in 27 pairs of cancerous and adjacent noncancerous tissues originating from patients with NSCLC.

RESULTS

Total VEGF, VEGF(121), and VEGF(165) were expressed in all specimens, whereas VEGF(183) and VEGF(189) were present in small amounts in certain samples. Total VEGF, VEGF(121), and VEGF(165) mRNA was upregulated in cancerous compared with healthy tissues, whereas VEGF(183) and VEGF(189) expression tended to be higher in healthy tissues. The expression of VEGFRs was similar between matched specimens. No correlation was found between the expression of total VEGF or VEGF splice variants and the clinicopathological characteristics of tumors. The expression patterns of VEGF splice variants differed between tissue pairs. VEGF(121) was the major variant expressed in all samples; however, its relative expression was higher in cancerous tissues. The relative expression of VEGF(183) and VEGF(189) was upregulated in healthy lung tissues, whereas the ratio of VEGF(165) to total VEGF was similar between matched specimens.

CONCLUSIONS

The expression pattern of certain VEGF splice variants is altered during tumorigenesis. Our data support the hypothesis that during malignant progression an angiogenic switch favoring the shorter diffusible isoforms occurs.

Expression of ADAMs and their inhibitors in sputum from patients with asthma

ADAMs (a disintegrin and metalloprotease) constitute a family of cell surface proteins containing disintegrin and metalloprotease domains which associate features of adhesion molecules and proteases. ADAMTSs (a disintegrin and metalloprotease with thrombospondin motifs) bear thrombospondin type I motifs in C-terminal extremity, and most of them are secreted proteins. Because genetic studies have shown that ADAM-33 gene polymorphisms are associated with asthma, we designed this study to assess mRNA expression profile of several ADAM and ADAMTS proteases in sputum from patients with asthma and to investigate the relationship between expression of these proteases and asthma-associated inflammation and airway obstruction. mRNA expression profile of selected ADAM and ADAMTS proteinases (ADAM-8, -9, -10, -12, -15, -17, and -33; ADAMTS-1, -2, -15, -16, -17, -18, and -19), their physiological inhibitors TIMP-1 and TIMP-3, and RECK, a membrane-anchored MMP activity regulator, was obtained by RT-PCR analysis performed on cells collected by sputum induction from 21 patients with mild to moderate asthma and 17 healthy individuals. mRNA levels of ADAM-8, ADAM-9, ADAM-12, TIMP-1, and TIMP-3 were significantly increased, whereas mRNA levels coding for ADAMTS-1, ADAMTS-15, and RECK were significantly decreased in patients with asthma compared with control patients. ADAM-8 expression was negatively correlated with the forced expiratory volume at the first second (FEV(1)) (r = -0.57, P < 0.01), whereas ADAMTS-1 and RECK expressions were positively correlated to FEV(1) (r = 0.45, P < 0.05, and r = 0.55, P = 0.01, respectively). We conclude that expression of ADAMs and ADAMTSs and their inhibitors is modulated in airways from patients with asthma and that these molecules may play a role in the pathogenesis of asthma.

Expression of ADAMs and their inhibitors in sputum from patients with asthma

ADAMs (a disintegrin and metalloprotease) constitute a family of cell surface proteins containing disintegrin and metalloprotease domains which associate features of adhesion molecules and proteases. ADAMTSs (a disintegrin and metalloprotease with thrombospondin motifs) bear thrombospondin type I motifs in C-terminal extremity, and most of them are secreted proteins. Because genetic studies have shown that ADAM-33 gene polymorphisms are associated with asthma, we designed this study to assess mRNA expression profile of several ADAM and ADAMTS proteases in sputum from patients with asthma and to investigate the relationship between expression of these proteases and asthma-associated inflammation and airway obstruction. mRNA expression profile of selected ADAM and ADAMTS proteinases (ADAM-8, -9, -10, -12, -15, -17, and -33; ADAMTS-1, -2, -15, -16, -17, -18, and -19), their physiological inhibitors TIMP-1 and TIMP-3, and RECK, a membrane-anchored MMP activity regulator, was obtained by RT-PCR analysis performed on cells collected by sputum induction from 21 patients with mild to moderate asthma and 17 healthy individuals. mRNA levels of ADAM-8, ADAM-9, ADAM-12, TIMP-1, and TIMP-3 were significantly increased, whereas mRNA levels coding for ADAMTS-1, ADAMTS-15, and RECK were significantly decreased in patients with asthma compared with control patients. ADAM-8 expression was negatively correlated with the forced expiratory volume at the first second (FEV(1)) (r = -0.57, P < 0.01), whereas ADAMTS-1 and RECK expressions were positively correlated to FEV(1) (r = 0.45, P < 0.05, and r = 0.55, P = 0.01, respectively). We conclude that expression of ADAMs and ADAMTSs and their inhibitors is modulated in airways from patients with asthma and that these molecules may play a role in the pathogenesis of asthma.

Targeting ADAMS and ERBBs in lung cancer

Aberrant ERBB receptor activity contributes to the development of many human cancers. Receptor overexpression, kinase domain (KD) mutations, and autocrine ligand production contribute to ERBB activation in human tumors. ERBB-targeted tyrosine kinase inhibitors (TKIs) and monoclonal antibodies are used in cancer treatment; however, clinical hurdles, including patient selection and TKI resistance, need to be overcome in order to optimize therapy. This minireview will discuss recent findings on possible mechanisms leading to ERBB-targeted therapy resistance and potential means to overcome them.