Properties and clinical relevance of MTA1 protein in human cancer

CRISPR/Cas9 knockout of MTA1 enhanced RANKL-induced osteoclastogenesis in RAW264.7 cells partly via increasing ROS activities

Metastasis-associated protein 1 (MTA1), belonging to metastasis-associated proteins (MTA) family, which are integral parts of nucleosome remodelling and histone deacetylation (NuRD) complexes. However, the effect of MTA1 on osteoclastogenesis is unknown. Currently, the regulation of MTA1 in osteoclastogenesis was reported for the first time. MTA1 knockout cells (KO) were established by CRISPR/Cas9 genome editing. RAW264.7 cells with WT and KO group were stimulated independently by RANKL to differentiate into mature osteoclasts. Further, western blotting and quantitative qRT-PCR were used to explore the effect of MTA1 on the expression of osteoclast-associated genes (including CTSK, MMP9, c-Fos and NFATc1) during osteoclastogenesis. Moreover, the effects of MTA1 on the expression of reactive oxygen species (ROS) in osteoclastogenesis was determined by 2', 7' -dichlorodihydrofluorescein diacetate (DCFH-DA) staining. Nuclear translocation of Nrf2 was assessed by immunofluorescence staining and western blotting. Our results indicated that the MTA1 deletion group could differentiate into osteoclasts with larger volume and more TRAP positive. In addition, compared with WT group, KO group cells generated more actin rings. Mechanistically, the loss of MTA1 increased the expression of osteoclast-specific markers, including c-Fos, NFATc1, CTSK and MMP-9. Furthermore, the results of qRT-PCR and western blotting showed that MTA1 deficiency reduced basal Nrf2 expression and inhibited Nrf2-mediated expression of related antioxidant enzymes. Immunofluorescence staining demonstrated that MTA1 deficiency inhibited Nrf2 nuclear translocation. Taken together, the above increased basal and RANKL-induced intracellular ROS levels, leading to enhanced osteoclast formation.

Metastatic tumor antigen 1 contributes to hepatocarcinogenesis posttranscriptionally through RNA-binding function

BACKGROUND AND AIMS

Both nuclear and cytoplasmic overexpression of metastatic tumor antigen 1 (MTA1) contributes to tumorigenesis of HCC. Most studies have focused on nuclear MTA1 whose function is mainly a chromatin modifier regulating the expression of various cancer-promoting genes. By contrast, the molecular mechanisms of cytoplasmic MTA1 in carcinogenesis remain elusive. Here, we reveal a role of MTA1 in posttranscriptional gene regulation.

APPROACH AND RESULTS

We conducted the in vitro and in vivo RNA-protein interaction assays indicating that MTA1 could bind directly to the 3'-untranslated region of MYC RNA. Mutation at the first glycine of the conserved GXXG loop within a K-homology II domain-like structure in MTA1 (G78D) resulted in the loss of RNA-binding activity. We used gain- and loss-of-function strategy showing that MTA1, but not the G78D mutant, extended the half-life of MYC and protected it from the lethal -7-mediated degradation. The G78D mutant exhibited lower activity in promoting tumorigenesis than wild-type in vitro and in vivo. Furthermore, RNA-immunoprecipitation sequencing analysis demonstrated that MTA1 binds various oncogenesis-related mRNAs besides MYC . The clinical relevance of cytoplasmic MTA1 and its interaction with MYC were investigated using HBV-HCC cohorts with or without early recurrence. The results showed that higher cytoplasmic MTA1 level and MTA1- MYC interaction were associated with early recurrence.

CONCLUSIONS

MTA1 is a generic RNA-binding protein. Cytoplasmic MTA1 and its binding to MYC is associated with early recurrence in patients with HBV-HCC. This function enables it to regulate gene expression posttranscriptionally and contributes to hepatocarcinogenesis.

RUNX2 recruits the NuRD(MTA1)/CRL4B complex to promote breast cancer progression and bone metastasis

Runt-related transcription factor 2 (RUNX2) is an osteogenesis-related transcription factor that has emerged as a prominent transcription repressing factor in carcinogenesis. However, the role of RUNX2 in breast cancer metastasis remains poorly understood. Here, we show that RUNX2 recruits the metastasis-associated 1 (MTA1)/NuRD and the Cullin 4B (CUL4B)-Ring E3 ligase (CRL4B) complex to form a transcriptional-repressive complex, which catalyzes the histone deacetylation and ubiquitylation. Genome-wide analysis of the RUNX2/NuRD(MTA1)/CRL4B complex targets identified a cohort of genes including peroxisome proliferator-activated receptor alpha (PPARα) and superoxide dismutase 2 (SOD2), which are critically involved in cell growth, epithelial-to-mesenchymal transition (EMT) and invasion. We demonstrate that the RUNX2/NuRD(MTA1)/CRL4B complex promotes the proliferation, invasion, tumorigenesis, bone metastasis, cancer stemness of breast cancer in vitro and in vivo. Strikingly, RUNX2 expression is upregulated in multiple human carcinomas, including breast cancer. Our study suggests that RUNX2 is a promising potential target for the future treatment strategies of breast cancer.

Molecular Mechanisms and Animal Models of HBV-Related Hepatocellular Carcinoma: With Emphasis on Metastatic Tumor Antigen 1

Hepatocellular carcinoma (HCC) is an important cause of cancer death worldwide, and hepatitis B virus (HBV) infection is a major etiology, particularly in the Asia-Pacific region. Lack of sensitive biomarkers for early diagnosis of HCC and lack of effective therapeutics for patients with advanced HCC are the main reasons for high HCC mortality; these clinical needs are linked to the molecular heterogeneity of hepatocarcinogenesis. Animal models are the basis of preclinical and translational research in HBV-related HCC (HBV-HCC). Recent advances in methodology have allowed the development of several animal models to address various aspects of chronic liver disease, including HCC, which HBV causes in humans. Currently, multiple HBV-HCC animal models, including conventional, hydrodynamics-transfection-based, viral vector-mediated transgenic, and xenograft mice models, as well as the hepadnavirus-infected tree shrew and woodchuck models, are available. This review provides an overview of molecular mechanisms and animal models of HBV-HCC. Additionally, the metastatic tumor antigen 1 (MTA1), a cancer-promoting molecule, was introduced as an example to address the importance of a suitable animal model for studying HBV-related hepatocarcinogenesis.

Prognostic value of MTA1, SOX4 and EZH2 expression in esophageal squamous cell carcinoma

Esophageal cancer has always been one of the major malignant tumor types affecting the health of the Chinese population. Metastasis-associated protein 1 (MTA1), SOX4 and enhancer of zeste homolog 2 (EZH2) are all potent inducers of invasion and metastasis in esophageal squamous cell carcinoma (ESCC). However, the role of these signaling molecules and their implication in ESCC have remained largely elusive. In the present study, the effects of MTA1, SOX4 and EZH2 on the prognosis of patients with ESCC were explored. Immunohistochemistry was used to examine the expression levels of MTA1, SOX4 and EZH2. The χ² test was used to analyze the association between protein expression and clinicopathological parameters. Kaplan-Meier curves and Cox proportional hazards model survival analysis was performed to investigate the effects of the three proteins examined on disease prognosis. The results indicated that MTA1 may be used as a prognostic and diagnostic marker for ESCC. To the best of our knowledge, the present study was the first to demonstrate that MTA1-SOX4 signaling is associated with prognosis in ESCC. However, no significant association was noted between SOX4 and EZH2 in the present study, which was inconsistent with previously reported findings. The function of the MTA1-SOX4-EZH2 axis and the interactions of the proteins involved require further investigation.

FTO downregulation mediated by hypoxia facilitates colorectal cancer metastasis

Fat mass and obesity-associated protein (FTO), an N6-methyladenosine (m⁶A) demethylase, participates in tumor progression and metastasis in many malignancies, but its role in colorectal cancer (CRC) is still unclear. Here, we found that FTO protein levels, but not RNA levels, were downregulated in CRC tissues. Reduced FTO protein expression was correlated with a high recurrence rate and poor prognosis in resectable CRC patients. Moreover, we demonstrated that hypoxia restrained FTO protein expression, mainly due to an increase in ubiquitin-mediated protein degradation. The serine/threonine kinase receptor associated protein (STRAP) might served as the E3 ligase and K216 was the major ubiquitination site responsible for hypoxia-induced FTO degradation. FTO inhibited CRC metastasis both in vitro and in vivo. Mechanistically, FTO exerted a tumor suppressive role by inhibiting metastasis-associated protein 1 (MTA1) expression in an m⁶A-dependent manner. Methylated MTA1 transcripts were recognized by an m⁶A "reader", insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2), which then stabilized its mRNA. Together, our findings highlight the critical role of FTO in CRC metastasis and reveal a novel epigenetic mechanism by which the hypoxic tumor microenvironment promotes CRC metastasis.

A TGF-β-MTA1-SOX4-EZH2 signaling axis drives epithelial-mesenchymal transition in tumor metastasis

MTA1, SOX4, EZH2, and TGF-β are all potent inducers of epithelial-mesenchymal transition (EMT) in cancer; however, the signaling relationship among these molecules in EMT is poorly understood. Here, we investigated the function of MTA1 in cancer cells and demonstrated that MTA1 overexpression efficiently activates EMT. This activation resulted in a significant increase in the migratory and invasive properties of three different cancer cell lines through a common mechanism involving SOX4 activation, screened from a gene expression profiling analysis. We showed that both SOX4 and MTA1 are induced by TGF-β and both are indispensable for TGF-β-mediated EMT. Further investigation identified that MTA1 acts upstream of SOX4 in the TGF-β pathway, emphasizing a TGF-β-MTA1-SOX4 signaling axis in EMT induction. The histone methyltransferase EZH2, a component of the polycomb (PcG) repressive complex 2 (PRC2), was identified as a critical responsive gene of the TGF-β-MTA1-SOX4 signaling in three different epithelial cancer cell lines, suggesting that this signaling acts broadly in cancer cells in vitro. The MTA1-SOX4-EZH2 signaling cascade was further verified in TCGA pan-cancer patient samples and in a colon cancer cDNA microarray, and activation of genes in this signaling pathway predicted an unfavorable prognosis in colon cancer patients. Collectively, our data uncover a SOX4-dependent EMT-inducing mechanism underlying MTA1-driven cancer metastasis and suggest a widespread TGF-β-MTA1-SOX4-EZH2 signaling axis that drives EMT in various cancers. We propose that this signaling may be used as a common therapeutic target to control epithelial cancer metastasis.

MTA1 promotes the invasion and migration of oral squamous carcinoma by inducing epithelial-mesenchymal transition via the hedgehog signaling pathway

The metastasis-associated gene 1 (MTA1) has previously been recognized as an oncogene in many tumors, and aberrant MTA1 expression has been related to invasion and migration; however, its role and underlying molecular mechanism in oral squamous carcinoma (OSCC) remain largely unexplored. In this work, we determined the expression of MTA1 in OSCC tissues and cell lines. The effect of MTA1 on metastasis and the role of MTA1 in the epithelial-to-mesenchymal transition (EMT) of OSCC cells were evaluated by assays both in vitro and in vivo. We also identified the key Hedgehog signaling pathway-related protein involved in the MTA1-induced EMT. We found that MTA1 expression was upregulated and positively related to the metastasis in OSCC tissues and cell lines. MTA1 overexpression promoted OSCC invasion, migration, and induced EMT, while its silencing had the opposite effect both in vitro and in vivo. Additionally, our data further revealed the relevant molecular mechanism, Hedgehog(Hh) signaling pathway contributed to the effect of MTA1 on the aggressive phenotypes of OSCC cells.These findings indicate that MTA1 enhances OSCC cells invasion and migration by inducing EMT via the Hedgehog signaling pathway, which suggests MTA1 may be an effective anti-OSCC therapeutic target.

Prognostic and clinical significance of metastasis-associated gene 1 overexpression in solid cancers: A meta-analysis

BACKGROUND

In the past 2 decades, metastasis-associated gene 1 (MTA1) has attracted attention for its close association with cancer progression and its roles in chromatin remodeling processes, making it a central gene in cancer. The present meta-analysis was performed to assess MTA1 expression in solid tumors.

MATERIALS AND METHODS

This analysis identified studies that evaluated the relationship between MTA1 expression and clinical characteristics or prognosis of patients with solid tumors via the PubMed, Cochrane Library, and Embase electronic databases. Fixed-effect and random-effect meta-analytical techniques were used to correlate MTA1 expression with outcome measures. The outcome variables are shown as odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI).

RESULTS

Analysis of 40 cohort studies involving 4564 cancer patients revealed a significant association of MTA1 overexpression with tumor patient age (>50 vs. <50 years: combined OR 0.73, 95% CI 0.57-0.94), tumor grade (G3/4 vs. G1/2: combined OR 1.94, 95% CI 1.48-2.53), tumor size (>3 cm vs. <3 cm: combined OR 2.35, 95% CI 1.73-3.19), T stage (T3/4 vs. T1/2: combined OR 2.11, 95% CI 1.74-2.56), lymph node metastasis (yes vs. no: combined OR 2.92, 95% CI 2.26-3.75), distant metastasis (yes vs. no: combined OR 2.26, 95% CI 1.42-3.59), TNM stage (III/IV vs. I/II: combined OR 2.50, 95% CI 1.84-3.38), vascular invasion (yes vs. no: combined OR 2.26, 95% CI 1.92-3.56), and poor overall survival time (HR 1.83; 95% CI: 1.53-2.20; P = .000).

CONCLUSIONS

Our analyses demonstrate that MTA1 was an effective predictor of a worse prognosis in tumor patients. Moreover, MTA1 may play important role in tumor progression and outcome, and targeting MTA1 may be a new strategy for anti-cancer therapy.

Characterization of metastatic tumor antigen 1 and its interaction with hepatitis B virus X protein in NF-κB signaling and tumor progression in a woodchuck hepatocellular carcinoma model

The metastatic tumor antigen 1 (MTA1) protein is associated with tumor invasiveness and poor prognosis in patients with hepatocellular carcinoma (HCC), particularly in those with hepatitis B virus (HBV)-related HCC. Chronically woodchuck hepatitis virus (WHV)-infected woodchuck is an ideal animal model for studying the pathogenesis of HBV-associated liver diseases, including HCC. To investigate the roles of MTA1 in HBV-associated hepatocarcinogenesis in the woodchuck model, we cloned the woodchuck MTA1 (wk-MTA1) complementary (c)DNA and characterized its molecular functions. The sequence and organization of the wk-MTA1 protein were highly conserved among different species. Similar to its expression in human HCC, wk-MTA1 was upregulated in woodchuck HCC, as determined at RNA and protein levels. Furthermore, an MTA1-spliced variant, wk-MTA1dE4, was overexpressed in woodchuck HCC, and it was attributed to approximately 50% of the total transcripts. The percentage of wk-MTA1dE4-overexpressed woodchuck HCCs was higher than that of the total wk-MTA1-overexpressed HCCs (77.8% vs 61.1%) and wk-MTA1dE4 may represent a more sensitive marker than the total wk-MTA1 in woodchuck HCC. We overexpressed or knocked down wk-MTA1 in a woodchuck HCC cell line and demonstrated that wk-MTA1 could interact with the WHV X protein (WHx) and play indispensable roles in WHx-mediated NF-κB activation and tumor cell migration- and invasion-promoting activities. In conclusion, our results support the hypothesis that woodchuck HCC recapitulates HBV-associated HCC with respect to the molecular characteristics of MTA1 and provides new clues for conducting mechanistic studies of MTA1 in HBV-associated hepatocarcinogenesis, including the possible clinical significance of wk-MTA1dE4.

MTA1 is a novel regulator of autophagy that induces tamoxifen resistance in breast cancer cells

Tamoxifen is commonly used to treat patients with ESR/ER-positive breast cancer, but its therapeutic benefit is limited by the development of resistance. Recently, alterations in macroautophagy/autophagy function were demonstrated to be a potential mechanism for tamoxifen resistance. Although MTA1 (metastasis-associated 1) has been implicated in breast tumorigenesis and metastasis, its role in endocrine resistance has not been studied. Here, we report that the level of MTA1 expression was upregulated in the tamoxifen resistant breast cancer cell lines MCF7/TAMR and T47D/TR, and knockdown of MTA1 sensitized the cells to 4-hydroxytamoxifen (4OHT). Moreover, knockdown of MTA1 significantly decreased the enhanced autophagy flux in the tamoxifen resistant cell lines. To confirm the role of MTA1 in the development of tamoxifen resistance, we established a cell line, MCF7/MTA1, which stably expressed MTA1. Compared with parental MCF7, MCF7/MTA1 cells were more resistant to 4OHT-induced growth inhibition in vitro and in vivo, and showed increased autophagy flux and higher numbers of autophagosomes. Knockdown of ATG7 or cotreatment with hydroxychloroquine, an autophagy inhibitor, restored sensitivity to 4OHT in both the MCF7/MTA1 and tamoxifen resistant cells. In addition, AMP-activated protein kinase (AMPK) was activated, probably because of an increased AMP:ATP ratio and decreased expression of mitochondrial electron transport complex components. Finally, publicly available breast cancer patient datasets indicate that MTA1 levels correlate with poor prognosis and development of recurrence in patients with breast cancer treated with tamoxifen. Overall, our findings demonstrated that MTA1 induces AMPK activation and subsequent autophagy that could contribute to tamoxifen resistance in breast cancer.

NuRD subunit MTA1 interacts with the DNA non-homologous end joining Ku complex in cancer cells

Metastasis-associated antigen 1 (MTA1) is a chromatin modifier mediating DNA modification and gene expression. Ku70/Ku80 complex has been reported to be essential in DNA damage response. In an effort to explore the MTA1 interactome, we captured the Ku70/Ku80 complex with two specific MTA1 antibodies in a colon cancer cell line. We first validated the in vitro interaction between MTA1 and the Ku complex by co-immunoprecipitation (co-IP) analyses in cell lysate, showing that the interaction occurred mainly at the nucleus, but also existed in the cytoplasm at a lower level. We further visualized and confirmed their in vivo interaction using proximity ligation assay (PLA), which, in line with the in vitro analysis, also demonstrated a vast majority of interaction plots in the nucleus and a small number in the cytoplasm. We previously demonstrated that MTA1 distributed dynamically and periodically during the cell cycle. Here, through fluorescent colocalization, we found that MTA1 and Ku proteins colocalized well in the nucleus at interphase and moved synchronously from prophase to anaphase. Interestingly, at the time of telophase, when MTA1 was reported to re-enter the nucleus, they were separated and moved non-synchronously. Moreover, using in situ PLA, we visualized that the interaction occurred at both interphase and mitosis. At interphase, they interacted mainly in the nucleus, but during mitosis, they interact at the periphery of chromosomes. We also showed that MTA1 correlated well with Ku in both the cancerous and normal tissues, and that they cooperated in UV-induced DNA damage response. Collectively, our data uncover a specific interaction between MTA1 and Ku complex at both the nucleus and cytoplasm, and across the whole cell cycle. We therefore propose a potential functional crosstalk between NuRD and Ku complexes, the two most fundamental function units in cells, via physical interaction.

MTA1 interacts with Ku complex mainly in the nucleus at interphase and surrounding the chromosome during mitosis.

Clinicopathological Significance of MTA 1 Expression in Patients with Non-Small Cell Lung Cancer: A Meta-Analysis

Background:

Metastasis associated gene 1(MTA1) is one of the most deregulated molecules in human cancer and leads to cancer progression and metastasis. We performed a meta-analysis to determine the correlations between MTA1 expression and the clinicopathological characteristics of non-small cell lung cancer (NSCLC).

Methods:

We searched PubMed, Springer, Science Direct, Google Scholar and China National Knowledge Infrastructure (CNKI) for relevant articles. For statistical analyses, we used R3.1.1 software. The fixed or random effects model was employed based on the results of the statistical test for homogeneity.

Results:

Seven studies involving 660 NSCLC patients were included. The proportion of MTA1 overexpression with 95% confidence interval (95% CI) was 0.53(95% CI: 0.43-0.62) in NSCLC patients; 0.47(95% CI: 0.40-0.55) in age <60 years and 0.52(95% CI: 0.34-0.70) in age ≥60 years; 0.5(95% CI: 0.41-0.62) in males and 0.51(95% CI: 0.39-0.62) in females; 0.59(95% CI: 0.48-0.69) in squamous cell carcinoma (SC) and 0.57(95% CI: 0.46-0.67) in adenocarcinoma (AC); 0.39(95% CI: 0.23-0.56) in well-differentiated tumors, 0.44(95% CI: 0.37-0.51) in moderately differentiated tumors and 0.55(95% CI: 0.37-0.51) in poorly differentiated tumors; 0.48(95% CI: 0.36-0.60) in clinical grade (III-IV) NSCLC and 0.75 (95% CI: 0.69-0.81) in clinical grade (I-II) NSCLC; 0.58(95% CI: 0.45-0.71) in T Stage (T1/T2) NSCLC; 0.68(95% CI: 0.49-0.82) in NSCLC patients with lymph node positivity and 0.51(95% CI: 0.43-0.58) in NSCLC patients with lymph node negativity.

Conclusions:

These results indicated that MTA1 might be a valuable biomarker in the diagnosis of NSCLC. MTA1 overexpression was significantly associated with age ≥60 years, gender, histopathological type, clinical grade (I-II), T stage (T1/T2) and lymph node positivity in NSCLC patients.

MTA1 expression in human cancers - Clinical and pharmacological significance

Remarkably, majority of the cancer deaths are due to metastasis, not because of primary tumors. Metastasis is one of the important hallmarks of cancer. During metastasis invasion of primary tumor cells from the site of origin to a new organ occurs. Metastasis associated proteins (MTAs) are a small family of transcriptional coregulators that are closely associated with tumor metastasis. These proteins are integral components of nuclear remodeling and deacetylation complex (NuRD). By virtue of being integral components of NuRD, these proteins regulate the gene expression by altering the epigenetic changes such as acetylation and methylation on the target gene chromatin. Among the MTA proteins, MTA1 expression is very closely correlated with the aggressiveness of several cancers that includes breast, liver, colon, pancreas, prostate, blood, esophageal, gastro-intestinal etc. Considering its close association with aggressiveness in human cancers, MTA1 may be considered as a potential therapeutic target for cancer treatment. The recent developments in its crystal structure further strengthened the idea of developing small molecule inhibitors for MTA1. In this review, we discuss the recent trends on the diverse functions of MTA1 and its role in various cancers, with the focus to consider MTA1 as a 'druggable' target in the control of human cancers.

[Relationship between MTA1 Expression and Prognosis of Chinese Lung Cancer Patients: A Meta-analysis]

BACKGROUND

It has been proven that metastasis associated protein 1 (MTA1) was correlated with tumor invasion and migration and poor prognosis of several malignant carcinomas. The prognostic role of MTA1 expression in lung cancer remained controversial, we performed this meta-analysis to assess the prognostic value of MTA1 expression in lung cancer.

METHODS

A systematic literature search was conducted to identify eligible studies which dealing with the relationship between MTA1 expression and prognosis of lung cancer in PubMed, Embase, Wanfang databases, China Biology Medicine disc and China National Knowledge Infrastructure. The pooled hazard ratio (HR) were used to assess the relationship between MTA1 expression and prognosis of lung cancer. All data were analysed using the Stata 12.0 software.

RESULTS

A total of 712 Chinese lung cancer patients from 8 studies were included in this meta-analysis. There was significant heterogeneity existed in these studies (I2=59.0%, P=0.017), so we used a random effects model to calculate the pooled HR=2.07 (95%CI: 1.42-3.02, P<0.001). At the same time, we observed through stratified analysis by histology that there was no significant heterogeneity in non-small cell lung cancer (NSCLC), and the fixed effects model was used to calculate the pooled HR=1.66 (95%CI: 1.27-2.18, P<0.001).

CONCLUSIONS

Overexpression of MTA1 could be a marker of poor prognosis in Chinese NSCLC patients, but not in lung cancer or small cell lung cancer. Additional studies with larger samples and well-designed were required to derive the more precise outcome.

Metastasis-Associated Protein 1 Deficiency Results in Compromised Pulmonary Alveolar Capillary Angiogenesis in Mice

Background

The aim of this study was to investigate the effects of metastasis-associated protein 1 (MTA1) deficiency during angiogenesis of pulmonary alveolar capillaries in mice and to determine the molecular mechanisms involved.

Material/Methods

The expressions of MTA1, CD34, vascular endothelial growth factor (VEGF), alpha smooth muscle actin (α-SMA), and HIF-1α were analyzed in the lungs of MTA1-knockout (KO) and wild-type mice at embryonic day 18.5 and 2 months by quantitative PCR, immunoblotting, and immunohistochemistry. The morphological changes were investigated during pulmonary alveolar capillary formation. The heart weight/body weight (HW/BW) ratio and the size of the right ventricular wall cardiomyocytes were also measured. Regulation of MTA1 on HIF-1α was determined in vitro.

Results

MTA1 deficiency reduced the number of pulmonary alveolar capillaries compared to the wild-type mice. MTA1-KO mice exhibited a decreased expression of HIF-1α and VEGF in the lungs. The retarded growth of the MTA1-KO mice was also noticed during the first week after birth. Accordingly, MTA1 deficiency resulted in increased infant mortality. In surviving adult mice, MTA1 deficiency induced myocardial hypertrophy, highlighted by an increased heart weight/body weight ratio and larger cardiomyocytes. In cultured cells, HIF-1α and VEGF levels were significantly upregulated upon MTA1 overexpression, suggesting a close relationship between all 3 molecules.

Conclusions

MTA1 participates in the formation of pulmonary capillaries via stabilization of HIF-1α. This finding sheds new light on the function of MTA1 in lung development, opening new avenues for the diagnosis/treatment of related pulmonary diseases.

MTA1 promotes epithelial to mesenchymal transition and metastasis in non-small-cell lung cancer

The present study assessed the role of metastasis-associated protein 1 (MTA1) in epithelial to mesenchymal transition (EMT) and metastasis in non-small-cell lung cancer (NSCLC) cells using a normal lung epithelium cell line, three NSCLC cell lines, a mouse NSCLC model, and 56 clinical NSCLC samples. We observed that MTA1 overexpression decreased cellular adhesion, promoted migration and invasion, and changed cytoskeletal polarity. MTA1 knockdown had the opposite effects. MTA1 overexpression decreased E-cadherin, Claudin-1, and ZO-1 levels and increased Vimentin expression in vitro and in vivo, through activation of AKT/GSK3β/β-catenin signaling. However, treatment with the AKT inhibitor MK2206 did not completely rescue effects associated with MTA1 expression changes, indicating that pathways other than the AKT/GSK3β/β-catenin pathway could be involved in MTA1-induced EMT. Compared with normal lung tissues, MTA1 expression was elevated in NSCLC patient tissues and was correlated with American Joint Committee on Cancer stage, T stage, lymphatic metastasis, and patient overall survival. Additionally, MTA1 expression was positively associated with p-AKT and cytoplasmic β-catenin levels. These findings indicate MTA1 promotes NSCLC cell EMT and metastasis via AKT/GSK3β/β-catenin signaling, which suggests MTA1 may be an effective anti-NSCLC therapeutic target.

Significance of expression of MTA1 and RECK in carcinogenesis of colonic polyps

AIM

To detect the expression of MTA1 and RECK in colonic polyps and colorectal carcinoma tissues, and to explore the role of MTA1 and RECK in the carcinogenesis of colonic polyps.

METHODS

Immunochemical staining was used to detect the expression of MTA1 and RECK proteins in 104 cases of colorectal carcinoma, 114 cases of colonic polyps and 30 cases of normal colorectal mucosa.

RESULTS

The positive expression rate of MTA1 gradually increased from normal colorectal mucosa to tubular adenoma, villous adenoma and colorectal carcinoma (P < 0.05). The positive expression rate of MTA1 in middle-severe dysplasia group was significantly higher than that in the mild dysplasia group in colonic polyps (P < 0.05). The expression rates of RECK were 100.00%, 78.57%, 77.27%, and 53.85% in normal colonic tissue, tubular adenoma, villous adenoma and colon carcinoma, respectively. The positive expression rate of RECK gradually decreased from normal colonic tissues to tubular adenoma, villous adenoma and colon carcinoma. The expression rate of RECK in the severe dysplasia group was significantly lower than that in the mild dysplasia group in colonic polyps (P < 0.05).

CONCLUSION

MTA1 is highly expressed in colorectal carcinoma, but the expression of RECK is absent. MTA1 and RECK may be involved in the carcinogenesis of colonic polyps.

Dynein axonemal heavy chain 8 promotes androgen receptor activity and associates with prostate cancer progression

To gain insight into cellular factors regulating AR action that could promote castration resistant prostate cancer (CRPC), we performed a genome-wide RNAi screen for factors that promote ligand-independent AR transcriptional activity and integrated clinical databases for candidate genes that are positively associated with prostate cancer metastasis and recurrence. From this analysis, we identified Dynein Axonemal Heavy Chain 8 (DNAH8) as an AR regulator that displayed higher mRNA expression in metastatic than in primary tumors, and showed high expression in patients with poor prognosis. Axonemal dyneins function in cellular motility, but the function of DNAH8 in prostate cancer or other cell types has not been reported. DNAH8 is on chromosome 6q21.2, a cancer-associated amplicon, and is primarily expressed in prostate and testis. Its expression is higher in primary tumors compared to normal prostate, and is further increased in metastatic prostate cancers. Patients expressing high levels of DNAH8 have a greater risk of relapse and a poor prognosis after prostatectomy. Depletion of DNAH8 in prostate cancer cells suppressed AR transcriptional activity and proliferation. Androgen treatment increased DNAH8 mRNA expression, and AR bound the DNAH8 promoter sequence indicating DNAH8 is an AR target gene. Thus, DNAH8 is a new regulator of AR associated with metastatic tumors and poor prognosis.

Interplay between 15-lipoxygenase-1 and metastasis-associated antigen 1 in the metastatic potential of colorectal cancer

OBJECTIVES

Metastasis-associated antigen 1 (MTA1) is implicated in metastasis while 15-lipoxygenase-1 (15-LOX-1) reduces cell motility, when re-expressed in colorectal cancer (CRC). We aimed to understand any potential interplay between MTA1 and 15-LOX-1 in CRC metastasis.

MATERIALS AND METHODS

ALOX15 and MTA1 expression in tumour and normal samples were analysed from TCGA RNA-seq data, microarray data sets and a human CRC cDNA array. Western blots, chromatin immunoprecipitation (ChIP), luciferase assays and electrophoretic mobility shift assays (EMSA) were carried out in HT-29 and LoVo cells re-expressing 15-LOX-1 to determine NF- κB activity at the MTA1 promoter. Functional assays in cells ectopically expressing either 15-LOX-1, MTA-1 or both, were carried out to determine adhesion and cell motility.

RESULTS

Significantly higher expression of MTA1 was observed in tumours compared to normal tissues; MTA1 overexpression resulted in reduced adhesion in CRC cell lines. Re-expression of 15-LOX-1 in the CRC cell lines reduced expression of endogenous MTA1, corroborated by negative correlation between the two genes in two independent human CRC microarray data sets, with greater significance in specific subsets of patients. DNA binding and transcriptional activity of NF-κB at the MTA1 promoter was significantly lower in cells re-expressing 15-LOX-1. Functionally, the same cells had reduced motility, which was rescued when they overexpressed MTA1, and further corroborated by expressions of E-cadherin and vimentin.

CONCLUSIONS

Expression of MTA1 and 15-LOX-1 negatively correlated in specific subsets of CRC. Mechanistically, this is at least in part through reduced recruitment of NF-κB to the MTA1 promoter.

Structure, expression and functions of MTA genes

Metastatic associated proteins (MTA) are integrators of upstream regulatory signals with the ability to act as master coregulators for modifying gene transcriptional activity. The MTA family includes three genes and multiple alternatively spliced variants. The MTA proteins neither have their own enzymatic activity nor have been shown to directly interact with DNA. However, MTA proteins interact with a variety of chromatin remodeling factors and complexes with enzymatic activities for modulating the plasticity of nucleosomes, leading to the repression or derepression of target genes or other extra-nuclear and nucleosome remodeling and histone deacetylase (NuRD)-complex independent activities. The functions of MTA family members are driven by the steady state levels and subcellular localization of MTA proteins, the dynamic nature of modifying signals and enzymes, the structural features and post-translational modification of protein domains, interactions with binding proteins, and the nature of the engaged and resulting features of nucleosomes in the proximity of target genes. In general, MTA1 and MTA2 are the most upregulated genes in human cancer and correlate well with aggressive phenotypes, therapeutic resistance, poor prognosis and ultimately, unfavorable survival of cancer patients. Here we will discuss the structure, expression and functions of the MTA family of genes in the context of cancer cells.

Unravelling the Complexity and Functions of MTA Coregulators in Human Cancer

Since the initial recognition of the metastasis-associated protein 1 (MTA1) as a metastasis-relevant gene approximately 20 years ago, our appreciation for the complex role of the MTA family of coregulatory proteins in human cancer has profoundly grown. MTA proteins consist of six family members with similar structural units and act as central signaling nodes for integrating upstream signals into regulatory chromatin-remodeling networks, leading to regulation of gene expression in cancer cells. Substantial experimental and clinical evidence demonstrates that MTA proteins, particularly MTA1, are frequently deregulated in a wide range of human cancers. The MTA family governs cell survival, the invasive and metastatic phenotypes of cancer cells, and the aggressiveness of cancer and the prognosis of patients with MTA1 overexpressing cancers. Our discussion here highlights our current understanding of the regulatory mechanisms and functional roles of MTA proteins in cancer progression and expands upon the potential implications of MTA proteins in cancer biology and cancer therapeutics.