Metastasis-associated Protein 1 Protein Research Articles

Nicotinic Acid-Mediated Modulation of Metastasis-Associated Protein 1 Methylation and Inflammation in Brain Arteriovenous Malformation.

We explored metastasis-associated protein 1 (MTA1) promoter methylation in the development of brain arteriovenous malformation (BAVM). The clinical data of 148 sex- and age-matched BAVMs and controls were collected, and the MTA1 DNA methylation in peripheral white blood cells (WBC) was assessed by bisulfite pyrosequencing. Among them, 18 pairs of case-control samples were used for WBC mRNA detection, 32 pairs were used for WBC MTA1 protein measurement, and 50 pairs were used for plasma inflammatory factor analysis. Lipopolysaccharide (LPS) treatment was used to induce an inflammatory injury cell model of human brain microvascular endothelial cells (BMECS). 5-Aza-2'-deoxycytidine (5-AZA), nicotinic acid (NA), and MTA1 siRNAs were used in functional experiments to examine BMECS behaviors. RT-qPCR, Western blot, and ELISA or cytometric bead arrays were used to measure the expression levels of MTA1, cytokines, and signaling pathway proteins in human blood or BMECS. The degree of MTA1 promoter methylation was reduced in BAVM compared with the control group and was inversely proportional to MTA1 expression. Plasma ApoA concentrations in BAVM patients were significantly lower than those in controls and correlated positively with MTA1 promoter methylation and negatively with MTA1 expression. The expression of cytokine was markedly higher in BAVM than in controls. Cell experiments showed that 5-AZA decreased the methylation level of MTA1 and increased the expression of MTA1 protein. LPS treatment significantly increased cytokine concentrations (p < 0.05). NA and MTA1 silencing could effectively reverse the LPS-mediated increase in IL-6 and TNF-α expression through the NF-κB pathway. Our study indicated that NA may regulate MTA1 expression by affecting promoter DNA methylation, improve vascular inflammation through the NF-κB pathway, and alleviate the pathological development of BAVM.

Upregulation of MTA1 in Colon Cancer Drives A CD8+ T Cell-Rich But Classical Macrophage-Lacking Immunosuppressive Tumor Microenvironment.

BackgroundThe MTA1 protein encoded by metastasis-associated protein 1 (MTA1) is a key component of the ATP-dependent nucleosome remodeling and deacetylase (NuRD) complex, which is widely upregulated in cancers. MTA1 extensively affects downstream gene expression by participating in chromatin remodeling. Although it was defined as a metastasis-associated gene in first reports and metastasis is a process prominently affected by the tumor microenvironment, whether it affects the microenvironment has not been investigated. In our study, we elucidated the regulatory effect of MTA1 on tumor-associated macrophages (TAMs) and how this regulation affects the antitumor effect of cytotoxic T lymphocytes (CTLs) in the tumor microenvironment of colorectal cancer.MethodsWe detected the cytokines affected by MTA1 expression via a cytokine antibody array in control HCT116 cells and HCT116 cells overexpressing MTA1. Multiplex IHC staining was conducted on a colorectal cancer tissue array from our cancer cohort. Flow cytometry (FCM) was performed to explore the polarization of macrophages in the coculture system and the antitumor killing effect of CTLs in the coculture system. Bioinformatics analysis was conducted to analyze the Cancer Genome Atlas (TCGA) colorectal cancer cohort and single-cell RNA-seq data to assess the immune infiltration status of the TCGA colorectal cancer cohort and the functions of myeloid cells.ResultsMTA1 upregulation in colorectal cancer was found to drive an immunosuppressive tumor microenvironment. In the tumor microenvironment of MTA1-upregulated colorectal cancer, although CD8+ T cells were significantly enriched, macrophages were significantly decreased, which impaired the CTL effect of the CD8+ T cells on tumor cells. Moreover, upregulated MTA1 in tumor cells significantly induced infiltrated macrophages into tumor-associated macrophage phenotypes and further weakened the cytotoxic effect of CD8+ T cells.ConclusionUpregulation of MTA1 in colorectal cancer drives an immunosuppressive tumor microenvironment by decreasing the microphages from the tumor and inducing the residual macrophages into tumor-associated microphage phenotypes to block the activation of the killing CTL, which contributes to cancer progression.

The E3 ligase for metastasis associated 1 protein, TRIM25, is targeted by microRNA-873 in hepatocellular carcinoma

Tumor metastasis accounts for 90% of all cancer-related deaths. Epithelial to mesenchymal transition (EMT) considered to be centrally important in acquired resistance to chemotherapy and in progression of tumors to secondary organs. One of the important mediators of metastatic progression in hepatocellular carcinoma (HCC) is the metastasis associated protein 1 (MTA-1). We have earlier shown that in the context of HCC and normal liver cell lines, MTA-1 protein is actively stabilized in HCC cell lines and actively degraded in normal liver cells. We have also shown that TRIM25 is the E3 ligase that interacts with and degrades MTA-1 protein. The identity of the factor regulating expression of TRIM25 in normal liver cells and HCC is unknown. In the current work we elucidate that microRNA (miR)− 873 targets TRIM25 in HCC cells. Both metagenomic analysis and quantification of miR-873 and TRIM25 in 25 HCC patients revealed an inverse correlation between the two in HCC patients with high miR-873 and low TRIM25 expression, respectively. The expression pattern was mimicked in the normal liver cells THLE-2 and the HCC cell line, HuH6. In vitro luciferase reporter assays confirmed TRIM25 as the target of miR-873. Transient transfection of HuH6 cells with an anti-miR-873 antagomir significantly decreased both transwell motility in these cells. Furthermore, in in vivo xenograft assays treatment with anti-miR-873 antagomir significantly decreased hepatic nodules formation. Cumulatively, our data indicate that suppression of TRIM25 expression by high levels of miR-873 dictates MTA1 protein upregulation in HCC.

Metastasis-associated protein 1 (MTA1) in gastric cancer tissues is positively associated with poorer prognosis

BackgroundThe present study examined the clinical significance of metastasis-associated protein 1 (MTA1) in the progression and patient survival of gastric cancer. MethodsParaffin-embedded resected tissues of gastric cancer mucosa (n = 436) and adjacent normal mucosa (n = 92) were assessed immunohistochemically for MTA1 protein, and scored according to the percentage of cells positively stained for MTA1 combined with stain intensity. Associations between MTA1 staining scores and clinicopathological factors, including survival time, were evaluated. ResultsThe staining scores for MTA1 were significantly higher in gastric cancer tissues than in matched normal tissues. MTA1 scores positively correlated with tumor size, depth of invasion, presence of lymph node metastasis, lymphatic involvement, venous invasion, distal metastasis, and advanced clinical staging. Patients with high MTA1 scores in gastric cancer tissues had a significantly lower five-year survival rate compared with patients with low MTA1 scores. The multivariate analysis indicated that MTA1 protein levels in resected gastric cancer tissues, as reflected by immunohistochemical staining, are an independent prognostic index of gastric carcinoma (P < 0.01). ConclusionMTA1 immunopositivity was significantly associated with progression of gastric cancer, and may be helpful in gastric cancer prognosis.

EXPRESSION OF METASTASIS ASSOCIATED PROTEIN 1 AS A POSSIBLE PROGNOSTIC INDICATOR IN ORAL SQUAMOUS CELL CARCINOMA

INTRODUCTION: Lymph node (LN) metastasis is one of the most important prognostic factors related to survival of oral squamous cell carcinoma (OSCC). Although, metastasis associated protein 1 (MTA1) overexpression is closely correlated with the metastasis of several human cancers, its role in determining lymph node metastases in OSCC patients remains undefined. Proliferating Cell Nuclear Antigen (PCNA) is the most representative proliferating marker; yet there is a controversy as to whether it can be used as a prognostic marker in OSCC. OBJECTIVES: To evaluate the immunoexpression of MTA1 and PCNA in metastatic versus non-metastatic OSCC; and correlate it with LN metastasis. MATERIALS AND METHODS: MTA1 and PCNA immunoexpression was detected immunohistochemically in 20 OSCC specimens; 10 of which had metastatic LNs and 10 with non-metastatic LNs (used as a control group). Their correlation with LN metastasis was evaluated. RESULTS: MTA1 immunoexpression showed significant correlation with LN metastasis but not with the histologic grade of the tumor. Whereas, PCNA immunoexpression revealed a significant correlation with the histologic grade of the tumor, but not with nodal metastasis. CONCLUSIONS: The present study suggests that MTA1 protein may have a clinical potential to be used as a prognostic factor to identify pathologically node-negative OSCC patients who may be at high risk to develop regional metastasis. On the other hand, PCNA is unlikely to play an important role in predicting LN metastasis in OSCC patients. KEYWORDS: OSCC, MTA1, PCNA, LN metastasis.

Abstract 1637: 22(S)-Hydroxycholesterol, an antagonist of LXR, inhibits breast cancer cell migration

Abstract The Liver X Receptor (LXR) is a well-established ligand-regulated transcription factor involved in cholesterol homeostasis, lipid metabolism, and inflammation. Recent studies have reported a strong antiproliferative effect of LXRs in multiple types of cancer including prostate, colon, lung, and breast cancer. However, little is known about its association with cancer metastasis. Therefore we aimed to investigate the potential of LXR ligands in the context of breast cancer cell migration, and its underlying molecular mechanism. We first performed 2D-migration assay in 4T1 breast cancer cells. Treatment of an LXR antagonist significantly reduced the rate of 4T1 cell migration. However, LXR agonists such as T0901317, GW3965 did not have much effect. Next, we investigated the molecular mechanism of cell migration. Since the degree of invasion and metastasis of breast carcinoma is well correlated with elevated expression of metastasis-associated protein 1 (MTA1), we examined whether MTA1 expression could be regulated by LXR ligands. Interestingly, when LXR agonists were treated, increased protein expression of MTA1 and its downstream target protein HIF-1α was observed in MCF7, MDA-MB-231, and 4T1-Luc breast cancer cell lines. Transient expression of LXRα demonstrated the same results as well. Furthermore, the treat of 22(S)-HC down-regulated MTA1 and HIF-1α protein expressions. Together, our findings indicate that LXR influences migratory pattern of breast cancer cells, which may affect metastatic property of breast cancer cells via LXR-dependent regulation of MTA1 and HIF-1α expression. Citation Format: Sewon Hwang, Tae Young Na, Hyelin Na, Minho Lee, Mi-Ock Lee. 22(S)-Hydroxycholesterol, an antagonist of LXR, inhibits breast cancer cell migration. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1637.

Abstract 3862: Ormeloxifene, a novel pharmacological activator of PKD1 enhances docetaxel sensitivity in prostate cancer

Abstract Background: Prostate cancer (PrCa) is the second leading cause of cancer-related deaths in American Men. Docetaxel (DTX) is a standard first-line treatment for metastatic castration-resistant PrCa after the failure of hormone therapy. However, most PrCa patients who receive DTX experience only transient benefits and rapidly develop incurable drug resistance. Protein Kinase D1 (PKD1), one of the serine threonine kinases from PKD family is highly expressed in normal prostate tissues and is suppressed during PrCa progression. Accumulative evidence suggest a tumor suppressive role of PKD1 in PrCa, while other isoforms of PKD (PKD2 and PKD3) act as oncogene. In this study, we identified pharmacological agent Ormeloxifene (ORM) which selectively activates PKD1 and inhibits metastasis associated protein 1 (MTA1), thus induces sensitivity to DTX treatment in PrCa cells. Materials and Methods: We have used androgen-independent human PrCa cells (C4-2) which show low PKD1 expression compared to other PrCa cell lines. Cells were treated with 10 and 15 μM doses of ORM for 24 hrs and various functional assays (cell proliferation, colony formation, motility and invasion) were performed. In a parallel experiment, cells were treated with ORM (10 and 15 μM) for 24 hrs protein and RNA samples isolation. Protein lysates were used to investigate the effect of ORM on PKD1, PKD2, PKD3 and MTA1 protein levels. qRT-PCR was performed to investigate the effect of ORM on PKD1, PKD2 and PKD3 expression at mRNA levels. To investigate if ORM treatment sensitizes the effects of DTX, cells were treated with ORM and DTX alone or in combination. In-silico docking studies were performed to determine the putative molecular interaction of ORM with MTA1. Results: ORM treatment inhibits proliferation and clonogenic potential of C4-2 cells. We observed that ORM significantly induces PKD1 expression at protein and mRNA level in C4-2 cells. To determine whether this PKD1 inducing effects of ORM in PrCa cells is specific, we examined the effects of ORM on PKD2 and PKD3 at mRNA and protein levels. Interestingly, we observed that ORM treatment inhibits expression of oncogenic PKD3 isoform, however, no effect PKD2 was observed. MTA1 is involved in DTX resistance and ORM treatment effectively inhibited the expression of MTA1. However, there was no effect of DTX treatment on the expression of MTA1. We also observed that ORM treatment significantly potentiates the effect of DTX on cell viability and colony formation of C4-2 cells. In-silico docking studies between ORM and MTA1 showed four potential binding sites with best score at serine 270. Conclusion: Overall, our study defines ORM as a novel PKD1 activator/modulator which also inhibits a key metastasis associated protein, MTA1 and sensitizes the PrCa cells to DTX. Based on these results, it appears that ORM may be a novel therapeutic modality for advanced stage metastatic PrCa alone or in combination with DTX. Citation Format: Aditya Ganju, Bilal Bin Hafeez, Fathi Halaweish, Wei Li, Man Mohan Singh, Murali Mohan Yallapu, Subhash Chauhan, Meena Jaggi. Ormeloxifene, a novel pharmacological activator of PKD1 enhances docetaxel sensitivity in prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3862.

Clinicopathological and prognostic significance of metastasis-associated protein 1 expression and its correlation with angiogenesis in lung invasive adenocarcinomas, based on the 2011 IASLC/ATS/ERS classification.

Based on previous findings regarding the angiogenic activities and prognostic roles of metastasis-associated protein 1 (MTA1) in early-stage non-small cell lung cancer, the clinicopathological and prognostic significance of MTA1 protein expression, and its correlation with angiogenesis in lung invasive adenocarcinoma, were further assessed in the present study, according to the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification. High protein expression levels of MTA1 were commonly observed in patients with lung invasive adenocarcinoma, and were significantly correlated with tumor size (P=0.030), lymph node metastasis (P=0.021) and microvessel density (P=0.015). Survival analysis demonstrated that patients with high protein expression levels of MTA1 exhibited significantly shorter five-year disease-free and overall survival than those patients whose protein expression levels of MTA1 were low (24.5% vs. 48.7%, P=0.001, and 34.7% vs. 59.2%, P=0.005, respectively). In addition, Cox regression multivariate analysis demonstrated that high protein expression levels of MTA1 significantly correlated with unfavorable five-year disease-free survival (P=0.024). These findings indicate that MTA1 protein expression may possess clinical potential as an indicator of progressive phenotype. Therefore, MTA1 is a promising prognostic predictor to identify subgroups of patients with high risk of relapse, and a potentially novel therapeutic target for antiangiogenesis in patients with lung invasive adenocarcinoma.

Metastasis-associated protein 1 expression in oral squamous cell carcinomas: correlation with metastasis and angiogenesis.

Metastasis-associated protein 1 (MTA1) has been associated with poor prognosis in several carcinomas. Recent investigation has found that in different tumors, MTA1 protein significantly correlates with tumor angiogenesis, suggesting that MTA1 may be a possible angiogenesis-promoting molecule in malignant tumors. Thus, the current study was performed to determine the role of MTA1 protein in the biological behavior of oral squamous cell carcinoma and its relation with tumor angiogenesis. In this study, 44 oral squamous cell carcinomas and 15 normal epitheliums were reviewed by IHC staining for MTA1 and CD105. Frequency of MTA1 expression in SCCs was recorded as 97.7%, which was significantly higher than that of the control group (33.3%). Mean percentage of MTA1 expression in oral squamous cell carcinomas was 76.88 ± 25.33% which was significantly higher than that of the control group (22.81 ± 10.83). Our data showed a correlation between MTA1 expression with lymph node metastasis, tumor size and, stage. Evaluation of the correlation between MTA1 protein expression and micro vessel density showed that high micro vessel density was detected more frequently in tumors with MTA1 protein overexpression than in those without overexpression. In the present study, high expression of the MTA1 protein was seen in oral squamous cell carcinoma, and was closely associated with tumor progression and increased tumor angiogenesis. The findings may indicate that MTA1 protein has clinical potentials as a useful indicator of progressive phenotype, a promising prognostic predictor to identify patients with poor prognosis and may be a potential novel therapeutic target of anti-angiogenesis for patients with oral squamous cell carcinoma.

Effects of antioxidants on drugs used against testicular cancer-induced alterations in metastasis-associated protein 1 signaling in the rat testis

Metastasis-associated protein 1 (MTA1) is involved in tumor growth and metastasis of cancers. Being a component of nucleosome remodeling and histone deacetylase complex, the protein is also associated with DNA damage response pathway. Since the protein is involved in cancer pathology, we first investigated the effects of bleomycin, etoposide, and cisplatin (BEP) on MTA1 signaling in the testis. Second, since the antioxidants (AOs) have protective effects, we further investigated whether or not an AO cocktail modulates the effects of the drugs. Adult male Sprague Dawley rats (N = 4) were treated either with saline, or AO (α-tocopherol, l-ascorbic acid, zinc, and selenium), or therapeutic dose levels of etoposide (15 mg/kg) and cisplatin (3 mg/kg) from day 1-4 of the week and B (1.5 mg/kg) on the second day of the week, or BEP + AO. The real-time polymerase chain reaction showed that MTA1 and MTA1s (short form) gene expression was downregulated in AO (100% and 100%), BEP (86% and 71%), and BEP + AO (97% and 93%) groups. Western blotting and immunohistochemistry results showed that unnormalized MTA1 protein expression was upregulated in AO (38%) and BEP + AO (34%) groups; however, the MTA1/β-actin ratio was upregulated in all treated groups (21, 19, and 15%, respectively). In conclusion, the results indicate that both BEP and AO suppress MTA1 and MTA1s transcription, which may render the germ cells to be more prone to apoptosis. However, upregulation of MTA1 protein expression may be related to induced DNA damage. Modulation of MTA1 signaling is a novel mechanism of action of BEP and AO, which may be useful in developing newer anticancer drugs.

Down-regulation of MTA1 protein leads to the inhibition of migration, invasion, and angiogenesis of non-small-cell lung cancer cell line

Metastasis-associated protein 1 (MTA1) high expression has been detected in a wide variety of human aggressive tumors and plays important roles in the malignant biological behaviors such as invasion, metastasis, and angiogenesis. However, the specific roles and mechanisms of MTA1 protein in regulating the malignant behaviors of non-small-cell lung cancer (NSCLC) cells still remain unclear. To elucidate the detailed functions of MTA1 protein, we down-regulated the MTA1 protein expression in NSCLC cell line by RNA interference (RNAi) in vitro, and found that down-regulation of MTA1 protein significantly inhibited the migration and invasion potentials of 95D cells. Further research revealed that down-regulation of MTA1 protein significantly decreased the activity of matrix metalloproteinase-9, which could be the mechanism responsible for the inhibition of 95D cells migration and invasion. In addition, the tube formation assay demonstrated that the number of complete tubes induced by the conditioned medium of MTA1-siRNA 95D cells was significantly smaller than that of 95D cells. These findings demonstrate that MTA1 protein plays important roles in regulating the migration, invasion, and angiogenesis potentials of 95D cells, suggesting that MTA1 protein down-regulation by RNAi might be a novel therapeutic approach to inhibit the progression of NSCLC.

Close Association of Metastasis‐Associated Protein 1 Overexpression with Increased Angiogenesis and Poor Survival in Patients with Histologically Node‐Negative Gastric Cancer

Although metastasis-associated protein 1 (MTA1) has been recently demonstrated as a potent angiogenesis-promoting factor in various malignant tumors, its angiogenic property in gastric cancer (GC) remains unclear. This study has detected the expression of MTA1 protein in surgically resected tissues of pathologic N0 (pN0) GC and further investigated its relation with other clinicopathologic factors and tumor angiogenesis and prognosis. MTA1 protein expression was detected immunohistochemically in 111 pN0 GC specimens. Its correlations with clinicopathologic factors and tumor prognosis were evaluated. The intratumoral microvessel density (MVD) was assessed based on CD105 antigen immunoreactivity and analyzed for correlation with MTA1 protein expression. Overexpression of MTA1 was detected in 36.04 % of patients and exhibited a significant association with tumor size and MVD. Survival analysis demonstrated that both overall (OS) and disease-free (DFS) survivals in patients overexpressing MTA1 were significantly poorer than those without MTA1 overexpression 5 years after the operation (both p < 0.001). Multivariate survival analysis demonstrated that MTA1 overexpression was an independent prognosticator for unfavorable OS and DFS (p < 0.001, respectively). MTA1 overexpression is frequently observed in pN0 GC patients and is significantly associated with increased angiogenesis and poor prognosis. Detection of MTA1 protein expression may help predict the relapse and prognosis of pN0 GC. Also, MTA1 protein may form a novel target for antiangiogenic therapy.

Metastasis‐associated Protein 1 Nuclear Expression is Closely Associated with Tumor Progression and Angiogenesis in Patients with Esophageal Squamous Cell Cancer

The purposes of the present study were to detect the expression of metastasis-associated protein 1 (MTA1) in patients with esophageal squamous cell cancer (ESCC), and to evaluate the relevance of MTA1 protein expression to the tumor progression, angiogenesis, and prognosis. Both MTA1 protein and intratumoral microvessels were examined by immunohistochemical staining in 131 ESCC patients who successfully underwent subtotal esophagectomy and esophagogastric anastomosis at Qilu Hospital between Jan 2004 and Dec 2005. Intratumoral microvessel density (MVD) was recorded by counting CD-34 positive immunostained endothelial cells. All statistical analyses were performed with SPSS 13.0 statistical software. High expression of MTA1 protein was detected in 57 cases and significantly correlated with tumor invasion depth (P = 0.041), lymph node metastasis (P = 0.021), pathologic stage (P = 0.003), and MVD (P = 0.044). Survival analysis showed that patients with MTA1 protein high expression had significantly poor overall 5-year survival (P = 0.002), and the factor found on multivariate analysis to significantly affect overall survival was only pathologic stage (P = 0.040). Further stratified survival analysis split by pathologic stage demonstrated that MTA1 protein high expression significantly predicted unfavorable prognosis among patients with pathologic stage II disease (P = 0.006). High expression of the MTA1 protein is common in ESCC, and is closely associated with tumor progression, increased tumor angiogenesis, and poor survival. These findings indicate that MTA1 protein has clinical potentials as a useful indicator of progressive phenotype, a promising prognostic predictor to identify patients with poor prognosis, and a potential novel therapeutic target of antiangiogenesis for patients with ESCC.

Overexpression of Metastasis-Associated Protein 1 is Significantly Correlated with Tumor Angiogenesis and Poor Survival in Patients with Early-Stage Non-Small Cell Lung Cancer

The aims of this work are to detect the expression levels of metastasis-associated protein 1 (MTA1) in patients with early-stage non-small cell lung cancer (NSCLC), and to investigate the relationship of MTA1 protein with clinicopathologic factors, tumor angiogenesis, and prognosis. One hundred and two patients with pathologic stage I NSCLC who successfully underwent curative surgical resection were enrolled in this study. Immunohistochemical staining for MTA1 and CD34 was performed using the streptavidin-peroxidase method, and intratumoral microvessel density (MVD) was recorded by counting CD34-positive immunostained endothelial cells. All statistical analyses were performed with SPSS statistical software to determine the effects of MTA1 protein on clinicopathologic factors, tumor angiogenesis, and prognosis. MTA1 protein overexpression was detected in 41 cases and was significantly associated with MVD (P = 0.008). MTA1 protein overexpression and high MVD were significantly associated with tumor relapse (P = 0.004 and 0.007) and poor 5-year disease-free survival (P = 0.001 and 0.004). Patients with MTA1 protein overexpression and high MVD had significantly poor overall survival (P = 0.005 and 0.043) and disease-specific survival (P = 0.006 and 0.031) at 5 years after operation. Multivariate analysis demonstrated that MTA1 protein overexpression was an independent prognosticator for unfavorable disease-free, overall, and disease-specific survival (P = 0.011, 0.024, and 0.046). MTA1 protein overexpression is common in early-stage NSCLC and is significantly associated with tumor angiogenesis and poor survival. These findings suggest that MTA1 may have clinical potential as a promising predictor to identify individuals with poor prognostic potential and as a possible novel target molecule of antiangiogenic therapy for patients with early-stage NSCLC.

Metastasis-associated protein 1 induces VEGF-C and facilitates lymphangiogenesis in colorectal cancer

To study the correlation between high metastasis-associated protein 1 (MTA1) expression and lymphangiogenesis in colorectal cancer (CRC) and its role in production of vascular endothelial growth factor-C(VEGF-C). Impact of high MTA1 and VEGF-C expression levels on disease progression and lymphovascular density (LVD, D2-40-immunolabeled) in 81 cases of human CRC was evaluated by immunohistochemistry. VEGF-C mRNA and protein expressions in human LoVo and HCT116 cell lines were detected by real-time polymerase chain reaction and Western blotting, respectively, with a stable expression vector or siRNA. The elevated MTA1 and VEGF-C expression levels were correlated with lymph node metastasis and Dukes stages (P < 0.05). Additionally, high MTA1 expression level was correlated with a large tumor size (P < 0.05). A significant correlation was found between MTA1 and VEGF-C protein expressions in tumor cells (r = 0.371, P < 0.05). Similar to the VEGF-C expression level, high MTA1 expression level was correlated with high LVD in CRC (P < 0.05). Furthermore, over-expression of MTA1 significantly enhanced the VEGF-C mRNA and protein expression levels, whereas siRNAs - knocked down MTA1 decreased the VEGF-C expression level. MTA1, as a regulator of tumor-associated lymphangiogenesis, promotes lymphangiogenesis in CRC by mediating the VEGF-C expression.

Abstract A24: Resveratrol-induced and MTA1-associated miRNAs in prostate cancer prevention

Abstract Prostate cancer (PCa) remains one of the most frequently diagnosed cancers in men in Western countries. Since noticeable geographic variations have been observed in the incidence of PCa, studies have implicated a “Western” diet in the development of PCa. Because of this and the nature of PCa, which is typically diagnosed in the elderly population wth a relatively slower rate of growth and progression, chemoprevention through dietary compounds promises to be an effective approach for PCa. Resveratrol (Res) (3,5,4’-trihydroxy-trans-stilbene), a natural compound found in grapes, peanuts and berries, is one of the most promising diet-derived chemopreventive agent with potential chemotherapeutic capacities. There is growing evidence that Res may contribute to chromatin remodeling that are important in cancer progression. Metastasis-associated protein 1 (MTA1), which is overexpressed in many cancer, is a part of nucleosome remodeling and deacetylation (NuRD) complex that mediates posttranslational modifications of histones and nonhistone proteins resulting in transcriptional gene silencing. The complex also contains histone deacetylases 1 and 2 (HDAC1 and 2). MTA1/HDAC1 subunit plays an essential role in governing deacetylation of histones and other proteins. We recently demonstrated that Res down-regulated MTA1 protein levels in PCa cells, leading to destabilization of MTA1/HDAC1/NuRD complex thus allowing acetylation and activation of tumor suppressor p53. MTA1 silencing by RNA interference further sensitized PCa cells to Res-dependent p53 acetylation, transcriptional activation of p21 and Bax and apoptosis. To further understand Res-induced MTA1-associated epigenetic alterations, we analyzed MTA1-associated and Res-induced microRNAs expression changes using LNCaP cells expressing and silenced for MTA1. We found that expression of 13 miRNA was increase, and 17 miRNAs was decreased in cells silenced for MTA1 gene. In addition, 28 miRNAs were overexpresed, and 23 miRNAs were degreased under Res treatment. Among these miRNAs were some with well-characterized cancer association, such as let-7g, miR-16-2, miR-26a, miR-20b, miR-27a, miR-22, miR-34a, miR-92 and others. The predicted targets for the overlapping miRNAs are significantly enriched for protein-coding oncogenes and tumor suppressors. Our data indicate that MTA1-associated miRNAs are involved in Res-mediated anticancer and preventive effects in prostate cancer. Citation Information: Cancer Prev Res 2010;3(12 Suppl):A24.

Localization and Androgen Regulation of Metastasis-Associated Protein 1 in Mouse Epididymis

BackgroundMetastasis-associated protein 1 (MTA1), the founding member of the MTA family of genes, can modulate transcription by influencing the status of chromatin remodeling. Despite its strong correlation with the metastatic potential of cancer cells, MTA1 can also regulate crucial cellular pathways by modifying the acetylation status. We have previously reported the presence of MTA1/MTA1 in human and mouse testes, providing the evidence for its involvement in the regulation of testicular function during murine spermatogenesis. The objective of present study was to further assess the localization of MTA1 in mouse epididymis on both transcriptional and translational level, and then to explore whether MTA1 expression is regulated by androgens and postnatal epididymal development.Methodology/Principal FindingsMice were deprived of circulating androgen by bilaterally castration and were then supplemented with exogenous testosterone propionate for one week. MTA1 was immunolocalized in the epithelium of the entire epididymis with the maximal expression in the nuclei of principal cells and of clear cells in proximal region. Its expression decreased gradually after castration, whereas testosterone treatment could restore the expression, indicating that the expression of this gene is dependent on androgen. During postnatal development, the protein expression in the epididymis began to appear from day 7 to day 14, increased dramatically from postnatal day 28, and peaked at adulthood onwards, coinciding with both the well differentiated status of epididymis and the mature levels of circulating androgens. This region- and cell-specific pattern was also conservative in normal human epididymis.ConclusionsOur data suggest that the expression of MTA1 protein could be regulated by androgen pathway and its expression level is closely associated with the postnatal development of the epididymis, giving rise to the possibility that this gene plays a potential role in sperm maturation and fertility.

Metastasis-Associated Protein 1 Nuclear Expression is Associated with Tumor Progression and Clinical Outcome in Patients with Non-small Cell Lung Cancer

Little research has been done to test the usefulness of metastasis-associated protein 1 (MTA1) as a prognostic marker for non-small cell lung cancer (NSCLC). In this study, we investigated MTA1 expression and its prognostic value for NSCLC. NSCLC surgical tissue samples were taken from 100 patients with NSCLC who had been followed up for more than 2 years. The expression of MTA1 protein was evaluated by immunohistochemistry, and the correlations between the expression of MTA1 and clinical features and the prognosis were analyzed. The difference of MTA1 protein expression between NSCLCs and their adjacent nonneoplastic lung tissues was analyzed in a tissue microarray. The change of MTA1 mRNA expression and protein expression after RNA interference (RNAi) was detected by real-time polymerase chain reaction, Western blot, and immunocytochemistry in NSCLC cell line 95D. Overexpression of MTA1 (immunoreactivity scoring >4) was shown in 61.0% of the NSCLC cases but only in 9.4% of their adjacent nonneoplastic lung tissues (p < 0.001). The MTA1 expression level was correlated with lymph node metastasis (p = 0.013) and clinical stage (p = 0.002). Survival analysis showed that the MTA1 overexpression group had a significantly shorter overall survival time than the MTA1 downexpression group (p = 0.003). However, multivariate analysis showed that MTA1 expression was not a significant and independent prognostic parameter for patients with NSCLC. After RNAi, the 95D cells exhibit consistent reduction in MTA1 mRNA expression and MTA1 protein expression. MTA1 protein expression is associated with tumor progression and clinical outcome in patients with NSCLC. Further molecular, cellular, and animal model studies on MTA1 gene will provide new clues for exploring the mechanism of carcinogenesis and tumor progression in patients with NSCLC.

Resveratrol enhances p53 acetylation and apoptosis in prostate cancer by inhibiting MTA1/NuRD complex

Dietary compounds and epigenetic influences are well recognized factors in cancer progression. Resveratrol (Res), a dietary compound from grapes, has anticancer properties; however, its epigenetic effects are understudied. Metastasis-associated protein 1 (MTA1) is a part of the nucleosome remodeling deacetylation (NuRD) corepressor complex that mediates posttranslational modifications of histones and nonhistone proteins resulting in transcriptional repression. MTA1 overexpression in prostate cancer (PCa) correlates with tumor aggressiveness and metastasis. In this study, we have identified a novel MTA1-mediated mechanism, by which Res restores p53-signaling pathways in PCa cells. We show, for the first time, that Res causes down-regulation of MTA1 protein, leading to destabilization of MTA1/NuRD thus allowing acetylation/activation of p53. We demonstrated that MTA1 decrease by Res was concomitant with accumulation of Ac-p53. MTA1 knockdown further sensitized PCa cells to Res-dependent p53 acetylation and recruitment to the p21 and Bax promoters. Furthermore, MTA1 silencing maximized the levels of Res-induced apoptosis and pro-apoptotic Bax accumulation. HDAC inhibitor SAHA, like MTA1 silencing, increased Res-dependent p53 acetylation and showed cooperative effect on apoptosis. Our results indicate a novel epigenetic mechanism that contributes to Res anticancer activities: the inhibition of MTA1/NuRD complexes due to MTA1 decrease, which suppresses its deacetylation function and allows p53 acetylation and subsequent activation of pro-apoptotic genes. Our study identifies MTA1 as a new molecular target of Res that may have important clinical applications for PCa chemoprevention and therapy, and points to the combination of Res with HDAC inhibitors as an innovative therapeutic strategy for the treatment of PCa.

E3 ubiquitin ligase COP1 regulates the stability and functions of MTA1

Metastasis-associated protein 1 (MTA1), a component of the nucleosome remodeling and histone deacetylation (NuRD) complex, is widely upregulated in human cancers. However, the mechanism for regulating its protein stability remains unknown. Here we report that MTA1 is an ubiquitinated protein and targeted by the RING-finger E3 ubiquitin-protein ligase constitutive photomorphogenesis protein 1 (COP1) for degradation via the ubiquitin-proteasome pathway. Induced expression of wild-type COP1 but not its RING motif mutants promotes the ubiquitination and degradation of MTA1, indicating that the ligase activity is required for the COP1-mediated proteolysis of MTA1. Conversely, depletion of endogenous COP1 resulted in a marked decrease in MTA1 ubiquitination, accompanied by a pronounced accumulation of MTA1 protein. MTA1, in turn, destabilizes COP1 by promoting its autoubiquitination, thus creating a tight feedback loop that regulates both MTA1 and COP1 protein stability. Accordingly, disruption of the COP1-mediated proteolysis by ionizing radiation leads to MTA1 stabilization, accompanied by an increased coregulatory function of MTA1 on its target. Furthermore, we discovered that MTA1 is required for optimum DNA double-strand break repair after ionizing radiation. These findings provide novel insights into the regulation of MTA1 protein and reveal a novel function of MTA1 in DNA damage response.