Metastasis tumor-associated protein-2 knockdown suppresses the proliferation and invasion of human glioma cells in vitro and in vivo

Loss of MTA2-mediated downregulation of PTK7 inhibits hepatocellular carcinoma metastasis progression by modulating the FAK-MMP7 axis

The expression of metastasis tumor-associated protein 2 (MTA2) and protein tyrosine kinase 7 (PTK7) is associated with hepatocellular carcinoma (HCC) progression. However, the functional effect and mechanism through which MTA2 regulates PTK7-mediated HCC progression remains unclear. Here, we found that MTA2 knockdown significantly down-regulated PTK7 expression in HCC cells (SK-Hep-1 and PLC/PRF/5). Data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases show that the PTK7 expression level was higher in HCC tissues than in normal liver tissues. In HCC patients, the PTK7 expression level clearly correlated with tumor stage and grade, lower overall survival (OS) correlated positively with MTA2 level, and PTK7 expression acted as a downstream factor for MTA2 expression. In addition, matrix metalloproteinase 7 (MMP7) expression was closely regulated by PTK7, and the mRNA and protein expression levels of MTA2 and PTK7 correlated positively with lower OS. MMP7 downregulation by PTK7 knockdown clearly decreased the migration and invasion abilities of HCC cells. In HCC cells, recombinant human MMP7 reversed the PTK7 knockdown-induced suppression of migration and invasion. Furthermore, deactivation of FAK using siFAK or FAK inhibitor (PF-573228, PF) synergistically contributed to PTK7 knockdown-inhibited FAK activity, MMP7 expression, and the migration and invasion abilities of HCC cells. Collectively, our findings show that PTK7 mediates HCC progression by regulating the MTA2-FAK-MMP7 axis and may be a diagnostic value for HCC patients.

Prognostic, Immunological, and Mutational Analysis of MTA2 in Pan-Cancer and Drug Screening for Hepatocellular Carcinoma

BACKGROUND

Metastasis-associated protein 2 (MTA2) is a member of the metastasis-associated transcriptional regulator family and is a core component of the nucleosome remodeling and histone deacetylation complex. Despite growing evidence that MTA2 plays a crucial role in the tumorigenesis of certain cancers, no systematic pan-cancer analysis of MTA2 is available to date. Therefore, the aim of our study is to explore the prognostic value of MTA2 in 33 cancer types and to investigate its potential immune function.

METHODS

by comprehensive use of databases from TCGA, GTEx, GEO, UCSC xena, cBioPortal, comPPI, GeneMANIA, TCIA, MSigDB, and PDB, we applied various bioinformatics approaches to investigate the potential role of MTA2, including analyzing the association of MTA2 with MSI, prognosis, gene mutation, and immune cell infiltration in different tumors. We constructed a nomogram in TCGA-LIHC, performed single-cell sequencing (scRNA-seq) analysis of MTA2 in hepatocellular carcinoma (HCC), and screened drugs for the treatment of HCC. Finally, immunohistochemical experiments were performed to verify the expression and prognostic value of MTA2 in HCC. In vitro experiments were employed to observe the growth inhibition effects of MK-886 on the HCC cell line HepG2.

RESULTS

The results suggested that MTA2 was highly expressed in most cancers, and MTA2 expression was associated with the prognosis of different cancers. In addition, MTA2 expression was associated with Tumor Mutation Burden (TMB) in 12 cancer types and MSI in 8 cancer types. Immunoassays indicated that MTA2 positively correlated with activated memory CD4 T cells and M0 macrophage infiltration levels in HCC. ScRNA-seq analysis based on the GEO dataset discovered that MTA2 was significantly expressed in T cells in HCC. Finally, the eXtreme Sum (Xsum) algorithm was used to screen the antitumor drug MK-886, and the molecular docking technique was utilized to reveal the binding capacity between MK-886 and the MTA2 protein. The results demonstrated excellent binding sites between them, which bind to each other through Π-alkyl and alkyl interaction forces. An immunohistochemistry experiment showed that MTA2 protein was highly expressed in HCC, and high MTA2 expression was associated with poor survival in HCC patients. MK-886 significantly inhibited the proliferation and induced cell death of HepG2 cells in a dose-dependent manner.

CONCLUSIONS

Our study demonstrated that MTA2 plays crucial roles in tumor progression and tumor immunity, and it could be used as a prognostic marker for various malignancies. MK-886 might be a powerful drug for HCC.

LncRNA HOTAIR promotes the invasion and metastasis of oral squamous cell carcinoma through metastasis-associated gene 2

Despite therapeutic advancements, there has been little improvement in the survival status of patients with oral squamous cell carcinoma (OSCC). HOX antisense intergenic RNA (HOTAIR) has been shown to be dysregulated in several cancer types. However, the roles of HOTAIR in OSCC remain largely unknown. In this study, we investigated the association of HOTAIR expression with clinicopathological features in OSCC patients and the crucial roles of HOTAIR in the modulation of tumor progression. Our results showed that HOTAIR was highly expressed both in OSCC tissue samples and cell lines compared with corresponding normal oral mucosa tissues and human oral keratinocytes. Its overexpression was positively correlated with TNM (tumor-node-metastases) stage, histological grade, and regional lymph node metastasis. The knockdown of HOTAIR by short hairpin RNA significantly decreased the migration, invasion, and epithelial-mesenchymal transition of OSCC cells in vitro. Moreover, there was a negative correlation between HOTAIR and microRNA-326 expression in OSCC tissue samples and cell lines. Luciferase reporter and loss-of-function assays revealed that HOTAIR acted as a competitive endogenous RNA effectively sponging miR-326, thereby regulating the derepression of metastasis-associated gene 2 (MTA2). Finally, the expression and clinical significance of MTA2 were analyzed in another cohort of OSCC tissue samples. High MTA2 expression was significantly correlated with clinicopathological features of advanced OSCC and poor prognosis for patients with OSCC. Collectively, HOTAIR overexpression promoted the progression of OSCC. The HOTAIR-miR-326-MTA2 axis may contribute to a better understanding of OSCC pathogenesis and be a potential therapeutic target for OSCC.

PMEPA1 isoform a drives progression of glioblastoma by promoting protein degradation of the Hippo pathway kinase LATS1

The Hippo signaling pathway controls organ development and is also known, in cancer, to have a tumor suppressing role. Within the Hippo pathway, we here demonstrate, in human gliomas, a functional interaction of a transmembrane protein, prostate transmembrane protein, androgen induced 1 (PMEPA1) with large tumor suppressor kinase 1 (LATS1). We show that PMEPA1 is upregulated in primary human gliomas. The PMEPA1 isoform PMEPA1a was predominantly expressed in glioma specimens and cell lines, and ectopic expression of the protein promoted glioma growth and invasion in vitro and in an orthotopic xenograft model in nude mice. In co-immunoprecipitation experiments, PMEPA1a associated with the Hippo tumor suppressor kinase LATS1. This interaction led to a proteasomal degradation of LATS1 through recruitment of the ubiquitin ligase, neural precursor cell expressed, developmentally downregulated 4 (NEDD4), which led to silencing of Hippo signaling. Alanine substitution in PMEPA1a at PY motifs resulted in failed LATS1 degradation. Targeting of a downstream component in the Hippo signaling pathway, YAP, with shRNA, interfered with the growth promoting activities of PMEPA1a in vitro and in vivo. In conclusion, the presented work shows that PMEPA1a contributes to glioma progression by a dysregulation of the Hippo signaling pathway and thus represents a promising target for the treatment of gliomas.

MTA2 as a Potential Biomarker and Its Involvement in Metastatic Progression of Human Renal Cancer by miR-133b Targeting MMP-9

Metastasis-associated protein 2 (MTA2) was previously known as a requirement to maintain malignant potentials in several human cancers. However, the role of MTA2 in the progression of renal cell carcinoma (RCC) has not yet been delineated. In this study, MTA2 expression was significantly increased in RCC tissues and cell lines. Increased MTA2 expression was significantly associated with tumour grade (p = 0.002) and was an independent prognostic factor for overall survival with a high RCC tumour grade. MTA2 knockdown inhibited the migration, invasion, and in vivo metastasis of RCC cells without effects on cell proliferation. Regarding molecular mechanisms, MTA2 knockdown reduced the activity, protein level, and mRNA expression of matrix metalloproteinase-9 (MMP-9) in RCC cells. Further analyses demonstrated that patients with lower miR-133b expression had poorer survival rates than those with higher expression from The Cancer Genome Atlas database. Moreover, miR-133b modulated the 3′untranslated region (UTR) of MMP-9 promoter activities and subsequently the migratory and invasive abilities of these dysregulated expressions of MTA2 in RCC cells. The inhibition of MTA2 could contribute to human RCC metastasis by regulating the expression of miR-133b targeting MMP-9 expression.

Metastasis-associated protein 2 regulates human hepatocellular carcinoma metastasis progression through modulating p38MAPK/MMP2 pathways

Studies have shown the overexpression of metastasis-associated protein 2 (MTA2) to be associated with hepatocellular carcinoma (HCC) progression. However, the molecular mechanism of MTA2 expression in HCC is unclear. In our study, we found a higher level of MTA2 in HCC tissues than in normal tissues and a significant correlation between tumor grade and overall survival of HCC patients. We also found that MTA2 inhibition reduced the migration and invasion capabilities of HCC cells, independent of cell proliferation. Mechanistic studies have suggested that MTA2 protein and mRNA are more highly expressed in SK-Hep-1 and Huh-7 cells compared with other HCC cells. MTA2 silencing drastically reduced migration and invasion capability and also inhibited matrix metalloproteinase 2 (MMP2) at the transcriptional and translation levels in both cells. In addition, treatment with the MMP2 antibody markedly impaired MTA2-knockdown-mediated inhibition of migration and invasion in SK-Hep-1 cells. Furthermore, MTA2 knockdown reduced the phosphorylation of the p38MAPK protein, whereas the inhibition of p38MAPK (SB203580 or si-p38) confirmed that blocking the p38MAPK pathway mediated MTA2-knockdown-inhibited migration and invasion in SK-Hep-1 cells. We demonstrated the molecular mechanism by which MTA2 inhibits human HCC cell metastasis through the p38MAPK/MMP2 pathways, which might be helpful in determining the diagnostic value of this protein in patients with HCC

Repression of metastasis-associated protein 2 for inhibiting metastasis of human oral cancer cells by promoting the p-cofilin-1/ LC3-II expression

BACKGROUND

The overexpression of metastasis-associated protein 2 (MTA2) contributes to human tumor progression and metastasis in various tumor cells. However, the role of MTA2 in human oral cancer progression remains unknown.

MATERIALS AND METHODS

MTA2 expression in human oral tumor tissues and cell lines was measured by immunohistochemistry and Western blotting. Cell proliferation and cell cycle were analyzed using MTT assay and flow cytometry. The effects of MTA2 on oral cell migration and invasion were investigated using migration and invasion assays. The expression of MTA2, p-cofilin-1, and MTA2-induced LC3-II levels were measured using Western blotting and an immunofluorescence assay.

RESULTS

Based on the human oral cancer tissue array and TCGA database, we found that MTA2 was increased in oral cancer tissues than in non-tumor oral tissues (P < .01). Moreover, MTA2 is significantly associated with tumor grade (P < .01) and the overall survival rate of patients with grade III tumor (P < .05). MTA2 expression in oral cancer cells was markedly higher than that in normal oral cells. Cell proliferation and cell cycle were not significantly changed in the cells inhibited by MTA2. MTA2 knockdown can inhibit cell migration and invasion of human oral cancer cells. Furthermore, we suggest that MTA2 inhibition enhances p-cofilin and LC3-II expression, and the knockdown of LC3-II expression in cells inhibited by MTA2 had the opposite effect.

CONCLUSION

These results indicate that MTA2 may serve as a candidate prognostic biomarker and that targeting autophagy is a potential therapeutic strategy for treating human oral cancer.

MTA2 promotes HCC progression through repressing FRMD6, a key upstream component of hippo signaling pathway

Discerning oncogenic drivers from passengers remains a major effort in understanding of the essence of the initiation and development of hepatocellular carcinoma (HCC), the most common primary liver malignancy and the third leading cause of cancer mortality worldwide. Here we report that MTA2, Metastasis Associated 1 Family Member 2, is significantly up-regulated in HCC. We show that high level of MTA2 expression is strongly correlated with advanced pathological stages and poor overall survival of the patients. Genome-wide identification of the transcriptional targets of MTA2 by ChIP-seq indicates that MTA2 represses a cohort of genes including FRMD6 that are critically involved in the growth and mobility of HCC. We demonstrate that the MTA2 promotes the proliferation and metastasis of HCC in vitro and in vivo through suppressing Hippo signaling pathway. Together, these results reveal a key role for the MTA2-FRDM6-Hippo axis in human hepatocarcinogenesis.

MTA2-mediated inhibition of PTEN leads to pancreatic ductal adenocarcinoma carcinogenicity

Metastasis-associated protein 2 (MTA2) is a core subunit of the nucleosome remodeling and deacetylating (NuRD) complex and functions by mediating chromatin remodeling and gene silencing. However, its biological actions and clinical significance in pancreatic ductal adenocarcinoma (PDAC) remain elusive. The aim of this study was to explore the function and regulation mechanism of MTA2 in PDAC. As shown in GEO, ICGC, and TCGA databases, a higher expression of MTA2 was noticed in the PDAC tissues than in the normal pancreatic tissues. Moreover, a higher expression level of MTA2 was associated with a shorter overall survival time in these public PDAC databases. We further investigated the underlying mechanisms of these observations by using a chromatin immunoprecipitation (ChIP)-based deep sequencing, luciferase reporter, and quantitative ChIP assays. We identified the repressive binding of MTA2 to the promoter of phosphatase and tensin homolog (PTEN). We also found that Snail recruited MTA2 and HDAC1 to suppress PTEN expression. Ectopic expression and knockdown of MTA2 were performed to evaluate the effects of this gene on PDAC cell proliferation, migration, and invasion. Using CCK-8, colony formation and transwell assays, and a xenograft tumor model, we revealed that MTA2 promoted PDAC cell proliferation, migration, and invasion in vitro and PDAC tumor growth in vivo by downregulation of PTEN. In benzyl isothiocyanate (BITC)-treated MIA Paca-2 cells and PANC-1 cells, MTA2 level decreased in a dose- and time-dependent manner with concomitant upregulation of PTEN level and downregulation of phosphorylated PI3K and AKT levels, providing evidence of the involvement of MTA2 and PTEN in the regulation of the PI3K/AKT pathway in BITC-mediated PDAC suppression. Collectively, these findings uncover a novel role for MTA2 in the regulation of PDAC progression and help to elucidate the mechanisms involved in this process.

Metastasis-associated protein 3 in colorectal cancer determines tumor recurrence and prognosis

Metastasis-associated protein family (MTA) promotes tumor cell invasion and metastasis of human malignancies. However, the novel component of MTA family, MTA3 was found to play conflicting roles in human malignancies. While the expression pattern and potential function of MTA3 in colorectal cancer has not been addressed yet. In the present study, we investigated the protein expression of MTA3 by immunohistochemistry assay, analyzed its association with tumor progression, recurrence and prognosis in239 cases of patients. Results showed that MTA3 expression in colorectal cancer was significantly decreased in colorectal cancer compared with normal specimens. Its expression was found to be correlated with tumor differentiation, metastases and TNM stage. Kaplan–Meier analysis proved that MTA3 was associated with both disease-free survival and overall survival of patients with colorectal cancer that patients with negative MTA3 expression tend to have unfavorable outcome. Moreover, cox's proportional hazards analysis showed that negative MTA3 expression was an independent prognostic marker of poor outcome. These results provided the first evidence that MTA3 level was decreased in colorectal cancer and significantly correlated with tumor cell invasion and metastasis. It also demonstrated that MTA3 might serve as a potential marker of tumor recurrence and prognosis of colorectal cancer.

Angiogenesis and evading immune destruction are the main related transcriptomic characteristics to the invasive process of oral tongue cancer

Metastasis of head and neck tumors is responsible for a high mortality rate. Understanding its biochemistry may allow insights into tumorigenesis. To that end we carried out RNA-Seq analyses of 5 SCC9 derived oral cancer cell lines displaying increased invasive potential. Differentially expressed genes (DEGs) were annotated based on p-values and false discovery rate (q-values). All 292 KEGG pathways related to the human genome were compared in order to pinpoint the absolute and relative contributions to the invasive process considering the 8 hallmarks of cancer plus 2 new defined categories, as well as we made with our transcriptomic data. In terms of absolute contribution, the highest correlations were associated to the categories of evading immune destruction and energy metabolism and for relative contributions, angiogenesis and evading immune destruction. DEGs were distributed into each one of all possible modes of regulation, regarding up, down and continuum expression, along the 3 stages of metastatic progression. For p-values twenty-six genes were consistently present along the tumoral progression and 4 for q-values. Among the DEGs, we found 2 novel potentially informative metastatic markers: PIGG and SLC8B1. Furthermore, interactome analysis showed that MYH14, ANGPTL4, PPARD and ENPP1 are amenable to pharmacological interventions.

Identification of candidate biomarkers that involved in the epigenetic transcriptional regulation for detection gastric cancer by iTRAQ based quantitative proteomic analysis

BACKGROUND

The sensitivities and specificities of biomarkers for gastric cancer are insufficient for clinical detection, and new diagnostics are therefore urgently required.

METHODS

A discovery set of gastric cancer tissues was labeled with iTRAQ reagents, separated using SCX chromatography, and identified using LC-ESI-MS/MS. A validation set of gastric cancer tissues was used to confirm the expression levels of potential markers.

RESULTS

The present study detected metastasis-associated protein 2 (MTA2) and Histone deacetylases 1 (HDAC1) proteins that were overexpressed in gastric cancer tissues compared with that in adjacent gastric tissue. The sensitivity and specificity of MTA2 in detecting 76 cases gastric cancers were 57.9% (95% CI: 46.5%-69.3%) and 55.3% (95% CI: 43.8%-66.7%), respectively. The sensitivity and specificity of HDAC1 were 61.8% (95% CI: 50.7%-73%) and 63.2% (95% CI: 52.1%-74.3%), respectively. The co-expression of MTA2 and HDAC1 in gastric cancer achieved 65.3% sensitivity (95% CI: 51.5%-79.1%) and 65.2% specificity (95% CI: 50.9%-79.5%), which was strongly associated with lymph node metastasis and TNM staging.

CONCLUSION

The present findings indicated a tight correlation between the MTA2 and HDAC1 expression level and lymph node metastasis and TNM staging in gastric cancers. Therefore, MTA2 and HDAC1 might be predictors of lymph node metastasis phenotype and possible target molecule for anticancer drug design in human gastric cancer.

Upregulation of metastasis-associated gene 2 promotes cell proliferation and invasion in nasopharyngeal carcinoma

Aims

Metastasis-associated gene 2 (MTA2) is reported to play an important role in tumor progression, but little is known about the role of MTA2 in nasopharyngeal carcinoma (NPC). The aim of the study was to explore the expression and function of MTA2 in NPC.

Methods

Expression of MTA2 in NPC tissues and cell lines was detected by immunohistochemistry and Western blotting. Relationship between MTA2 expression and clinicopathological features was analyzed. Stable MTA2-overexpressing and MTA2-siliencing NPC cells were established by transfection with plasmids encoding MTA2 cDNA and lentivirus-mediated short hairpin RNA, respectively. Cell viability was determined by Cell Counting Kit-8 and colony formation assay. Cell migration ability was evaluated by wound healing and transwell invasion assay. The impact of MTA2 knockdown on growth and metastasis of CNE2 cells in vivo was determined by nude mouse xenograft models. Expression of several Akt pathway proteins was detected by Western blotting.

Results

MTA2 was upregulated in NPC tissues and three NPC cell lines detected (CNE1, CNE2, and HNE1). MTA2 expression was related to clinical stage and lymph node metastasis of patients with NPC. MTA2 upregulation promoted proliferation and invasion of CNE1 cells, while MTA2 depletion had opposite effects on CNE2 cells. Moreover, MTA2 depletion suppressed growth and metastasis of CNE2 cells in vivo. MTA2 overexpression activated Akt and upregulated the expression of matrix metalloproteinase 7 and cyclin D1.

Conclusion

We conclude that MTA2 acts as an oncogene in tumorigenesis of NPC. MTA2 may be a potential target for gene therapy in NPC.

Expression of metastasis-associated protein 3 in human brain glioma related to tumor prognosis

Glioma represents a disparate group of tumors characterized by high invasion ability, and therefore it is of clinical significance to identify molecular markers and therapeutic targets for better clinical management. Previously, metastasis-associated protein family (MTA) is considered to promote tumor cell invasion and metastasis of human malignancies. Recently, the newly identified MTA3 has been shown to play conflicting roles in human malignancies, while the expression pattern and potential clinical significance of MTA3 in human glioma have not been addressed yet. In the present study, we investigated the protein expression of MTA3 by immunohistochemistry assay and analyzed its association with glioma prognosis in 186 cases of patients. Results showed that MTA3 expression was decreased in glioma compared with that in normal brain (P < 0.05). In addition, tumors with high MTA3 expression were more likely to be of low WHO grade (P = 0.005) and reserve of body function (P = 0.014). Survival analysis showed that decreased MTA3 expression was independently associated with unfavorable overall survival of patients (P < 0.001). These results provide the first evidence that MTA3 expression was decreased in human glioma and negatively associated with prognosis of patients, suggesting that MTA3 may play a tumor suppressor role in glioma.

MTA2 enhances colony formation and tumor growth of gastric cancer cells through IL-11

Background

We have preliminarily reported MTA2 expression in gastric cancer and its biological functions by using knockdown cell models, while the molecular mechanisms of MTA2 in regulating malignant behaviors are still unclear.

Methods

MTA2 overexpression models were established by transfection assay in gastric cancer cells BGC-823 and MKN28. Cell proliferation assay, colony formation in soft agar, wound-healing assay and transwell migration assay were performed with MTA2 overexpression and negative control (NC) cells. Subcutaneous xenografts and pulmonary metastasis models by BGC-823/MTA2 and BGC-823/NC cells were used to observe the capacity of growth and metastasis in vivo. Differential gene expression in MTA2 knockdown and overexpression cells was analyzed by microarrays. IL-11, which demonstrated as differential expression in microarray, was detected by real-time PCR, western blot, ELISA and immunohistochemistry staining. Recombinant human IL-11 (rhIL-11) was administrated in cell proliferation and colony formation as rescue assay.

Results

The numbers of colonies in soft agar were significantly more in BGC-823/MTA2 and MKN28/MTA2 cells, comparing with those in their NC cells. Capabilities of cell proliferation, wound-healing and cell migration were not significantly changed in MTA2 overexpression cells. The sizes of subcutaneous xenografts and pulmonary metastases of BGC-832/MTA2 cells were significantly larger than those in BGC-823/NC group. Differential expression of IL-11 was identified by genome expression microarray both in MTA2 knockdown and overexpression cells. IL-11 expression was elevated in BGC-823/MTA2 cells, whereas reduced in SGC-7901/shMTA2 cells. Administration of rhIL-11 recovered colony formation capacity of SGC-7901/shMTA2 cells.

Conclusions

MTA2 overexpression enhances colony formation and tumor growth of gastric cancer cells, but not plays important role in cancer cell migration and metastasis. IL-11 is one of the downstream effectors of MTA2 in regulating gastric cancer cells growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1366-y) contains supplementary material, which is available to authorized users.

Subcellular localization of MTA proteins in normal and cancer cells

The subcellular localization of a protein is closely linked to and indicates its function. The metastatic tumor antigen (MTA) family has been under continuous investigation since its identification two decades ago. MTA1, MTA2, and MTA3 are the main members of the MTA family. MTA1, as the representative member of this family, has been shown to be widely expressed in both embryonic and adult tissues, as well as in normal and cancerous conditions, indicating that MTA1 has functions both in physiological and pathological contexts. MTA1 is expressed at a higher level in most cancers than in their normal tissue counterparts. Even in normal cells, MTA1 levels vary a great deal from tissue to tissue. Importantly, MTA1 shows a multiple localization pattern in the cell, as do MTA2 and MTA3. Different MTA components in different subcellular compartments may exert different molecular functions in the cell. Previous studies revealed that MTA1 and MTA2 are predominately localized to the nucleus, while MTA3 is observed in both the nucleus and cytoplasm. Recent studies have reported that MTA1 is located in the nucleus, cytoplasm, and the nuclear envelope. In the nucleus, MTA1 dynamically interacts with chromatin in a MTA1-K532 methylation-dependent manner, whereas cytoplasmic MTA1 binds to the microtubule skeleton. MTA1 also shows a dynamic distribution during the cell cycle. Further investigations are needed to identify the exact subcellular localizations of MTA proteins. We review the sub-cellular localization patterns of the MTA family members and give a comprehensive overview of their respective molecular activities in multiple contexts.