Identification of hMex-3A and its effect on human bladder cancer cell proliferation

MEX3A promotes colorectal cancer migration, invasion and EMT via regulating the Wnt/β-catenin signaling pathway

BACKGROUND

Mex-3 RNA binding family members are well-established to be important in cancer development and progression. However, the functions of Mex-3 RNA binding family member A (MEX3A) in colorectal cancer (CRC) metastasis remain poorly understood. In this study, we aim to reveal the function and the mechanism of MEX3A in promoting CRC metastasis.

METHODS

We used multiple databases including TCGA database, UALCAN, LinkedOmics, CancerSEA, GeneMANIA and STRING database to investigate the expression, the functions and underlying molecular mechanism of MEX3A in CRC. Multiple experimental methods were adapted to determine the study, including real-time PCR (qPCR), immunohistochemistry (IHC), western blot (WB), transfection, transwell migration and invasion assays, immunofluorescence (IF).

RESULTS

We found that MEX3A was significantly upregulated and correlated to tumor stage and lymph nodal metastasis in CRC through bioinformatics analysis and tissue immunohistochemistry (IHC). The higher expression of MEX3A in CRC correlated with poor recurrence-free survival (RFS) and overall survival (OS). In vitro studies showed that knockdown of MEX3A suppressed EMT transition, invasion and metastasis of CRC cells. Mechanistically, we revealed that MEX3A promotes epithelial-mesenchymal transition (EMT), invasion and metastasis of CRC cells by upregulating the Wnt/β-catenin signaling pathway.

CONCLUSION

In conclusion, our study reveals that MEX3A promotes CRC migration, invasion and EMT via regulating the Wnt/β-catenin signaling pathway and could be a novel therapeutic target for this patient population.

Construction of a TP53 mutation-associated ceRNA network as prognostic biomarkers in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) continues to endanger human health worldwide. Regulatory networks of competing endogenous RNAs (ceRNAs) play important roles in HCC. TP53 is the second most often altered gene in HCC and has a significant role in regulating target genes such as miRNAs and lncRNAs.

Methods

Data from patients with TP53 mutation were collected through the cBioPortal database and differential analysis was performed to screen RNAs related to TP53 mutation. The lncRNA-miRNA-mRNA relationship was predicted by the miRcode, miRDB, and TargetScan databases. The ceRNA networks were screened and visualized by Cytoscape. Core ceRNA networks were generated by differential analysis, coexpression analysis, prognostic analysis and subcellular localization. Finally, methylation, mutation, PPI, GSEA, immunity and drug sensitivity analyses of MEX3A were performed to determine the role of MEX3A in HCC.

Results

We identified 1508 DEmRNAs, 85 DEmiRNAs and 931 DElncRNAs and obtained a ceRNA network including 28 lncRNAs, 4 miRNAs and 31 mRNAs. Twenty hub DERNAs in the TP53-altered-related ceRNA network were screened out by Cytoscape and the core ceRNA network (LINC00491/TCL6-hsa-miR-139-5p-MEX3A) was obtained by multiple analyses. In addition, we discovered that the methylation level of MEX3A was decreased and the mutation frequency was raised in HCC. Furthermore, elevated MEX3A expression was associated with alterations in the HCC immunological microenvironment.

Conclusion

We successfully constructed a reciprocal ceRNA network, which could provide new ideas for exploring HCC mechanisms and therapeutic approaches.

Transcriptome signatures of host tissue infected with African swine fever virus reveal differential expression of associated oncogenes

African swine fever (ASF) has emerged as a threat to swine production worldwide. Evasion of host immunity by ASF virus (ASFV) is well understood. However, the role of ASFV in triggering oncogenesis is still unclear. In the present study, ASFV-infected kidney tissue samples were subjected to Illumina-based transcriptome analysis. A total of 2463 upregulated and 825 downregulated genes were differentially expressed (p < 0.05). A literature review revealed that the majority of the differentially expressed host genes were key molecules in signaling pathways involved in oncogenesis. Bioinformatic analysis indicated the activation of certain oncogenic KEGG pathways, including basal cell carcinoma, breast cancer, transcriptional deregulation in cancer, and hepatocellular carcinoma. Analysis of host-virus interactions revealed that the upregulated oncogenic RELA (p65 transcription factor) protein of Sus scrofa can interact with the A238L (hypothetical protein of unknown function) of ASFV. Differential expression of oncogenes was confirmed by qRT-PCR, using the H3 histone family 3A gene (H3F3A) as an internal control to confirm the RNA-Seq data. The levels of gene expression indicated by qRT-PCR matched closely to those determined through RNA-Seq. These findings open up new possibilities for investigation of the mechanisms underlying ASFV infection and offer insights into the dynamic interaction between viral infection and oncogenic processes. However, as these investigations were conducted on pigs that died from natural ASFV infection, the role of ASFV in oncogenesis still needs to be investigated in controlled experimental studies.

Investigation of the Potential Correlation Between RNA-Binding Proteins in the Evolutionarily Conserved MEX3 Family and Non-small-Cell Lung Cancer

Members of the MEX3 (muscle excess 3) family, uniquely characterised as mRNA binding proteins, play emerging roles in the post-transcriptional regulation of programmed biological processes, including tumour cell death and immune mechanisms, and have been shown to be involved in a variety of diseases. However, the role of MEX3 in non-small cell lung cancer (NSCLC) has not been fully elucidated. In this study, we found no significant changes in the sequence and copy number of the MEX3 gene through analysis using the COSMIC database, revealing its stability during malignancy development. Its expression in NSCLC was examined using the Oncomine™ database, and the prognosis of each member gene was analysed by Kaplan–Meier. The results showed that overexpression of MEX3A, MEX3B, MEX3C and MEX3D was associated with significantly worse OS in patients with LUAD, while overexpression of MEX3D was also associated with significantly worse OS in patients with LUSC. Afterwards, we applied the Tumour Immunology Estimation Resource (TIMER) tool to assess the correlation between different MEX3 and infiltrative immune cell infiltration. Ultimately, we found that most MEX3 members were highly expressed in NSCLC, with high expression suggesting poor prognosis and correlating with immune cell infiltration. The complexity and heterogeneity of NSCLC was understood through MEX3, setting the framework for the prognostic impact of MEX3 in NSCLC patients and the development of new targeted therapeutic strategies in the future.

Processing body (P-body) and its mediators in cancer

In recent years, processing bodies (P-bodies) formed by liquid-liquid phase separation, have attracted growing scientific attention due to their involvement in numerous cellular activities, including the regulation of mRNAs decay or storage. These cytoplasmic dynamic membraneless granules contain mRNA storage and decay components such as deadenylase and decapping factors. In addition, different mRNA metabolic regulators, including m⁶A readers and gene-mediated miRNA-silencing, are also associated with such P-bodies. Cancerous cells may profit from these mRNA decay shredders by up-regulating the expression level of oncogenes and down-regulating tumor suppressor genes. The main challenges of cancer treatment are drug resistance, metastasis, and cancer relapse likely associated with cancer stem cells, heterogeneity, and plasticity features of different tumors. The mRNA metabolic regulators based on P-bodies play a great role in cancer development and progression. The dysregulation of P-bodies mediators affects mRNA metabolism. However, less is known about the relationship between P-bodies mediators and cancerous behavior. The current review summarizes the recent studies on P-bodies mediators, their contribution to tumor development, and their potential in the clinical setting, particularly highlighting the P-bodies as potential drug-carriers such as exosomes to anticancer in the future.

MicroRNA-139-5p Suppresses Cell Malignant Behaviors in Breast Cancer through Targeting MEX3A

OBJECTIVE

The study was designed to evaluate the underlying mechanism of microRNA-139-5p in breast cancer (BC).

METHODS

Expression statuses of microRNA-139-5p and MEX3A were measured by qRT-PCR and western blotting. The anticancer effect of microRNA-139-5p in vitro was tested by a set of assays. Interaction between microRNA-139-5p and MEX3A was validated by dual-luciferase detection.

RESULTS

MicroRNA-139-5p expression in BC cells was obviously low, while MEX3A was significantly overexpressed. MicroRNA-139-5p restrained proliferative, invasive, and migratory abilities of BC cells and increased apoptosis level of BC cells, while MEX3A exerted a promoting effect on BC cell growth. Dual-luciferase reporter detection confirmed that microRNA-139-5p bound to MEX3A 3'-UTR.

CONCLUSIONS

MicroRNA-139-5p inhibited the development of BC by targeting MEX3A. MicroRNA-139-5p/MEX3A may be a target for BC therapy.

Harnessing the Activation of RIG-I Like Receptors to Inhibit Glioblastoma Tumorigenesis

Glioblastoma (GB) is an incurable form of brain malignancy in an adult with a median survival of less than 15 months. The current standard of care, which consists of surgical resection, radiotherapy, and chemotherapy with temozolomide, has been unsuccessful due to an extensive inter- and intra-tumoral genetic and molecular heterogeneity. This aspect represents a serious obstacle for developing alternative therapeutic options for GB. In the last years, immunotherapy has emerged as an effective treatment for a wide range of cancers and several trials have evaluated its effects in GB patients. Unfortunately, clinical outcomes were disappointing particularly because of the presence of tumor immunosuppressive microenvironment. Recently, anti-cancer approaches aimed to improve the expression and the activity of RIG-I-like receptors (RLRs) have emerged. These innovative therapeutic strategies attempt to stimulate both innate and adaptive immune responses against tumor antigens and to promote the apoptosis of cancer cells. Indeed, RLRs are important mediators of the innate immune system by triggering the type I interferon (IFN) response upon recognition of immunostimulatory RNAs. In this mini-review, we discuss the functions of RLRs family members in the control of immune response and we focus on the potential clinical application of RLRs agonists as a promising strategy for GB therapy.

Comprehensive Analysis of Prognostic Value of MEX3A and Its Relationship with Immune Infiltrates in Ovarian Cancer

MEX3A is a critical RNA-binding ubiquitin ligase that is upregulated in various types of cancer. However, the correlations of MEX3A with prognosis and its molecular mechanism in ovarian cancer (OC) remain unclear. The expression level, prognostic values, and the genetic variations of MEX3A were analyzed via Gene Expression Profiling Interactive Analysis (GEPIA) Oncomine, Kaplan-Meier plotter, and cBioPortal. We used the LinkedOmics database to investigate the functions of MEX3A coexpressed genes and performed visualizing gene interaction network analysis on the GeneMANIA website. The correlations between MEX3A and cancer immune infiltration were analyzed by the Tumor Immune Estimation Resource (TIMER) site and the TISIDB database. Furthermore, in vitro analysis was performed to evaluate the biological functions of MEX3A in OC cells. Our study showed that the expression of the MEX3A in OC was higher than in normal tissues; it had the greatest prognostic value in OC, and strong physical interaction with PABPC1, LAMTOR2, KHDRBS2, and IGF2BP2, which indicated the association between MEX3A and immune infiltration. We also found that MEX3A was negatively related to infiltrating levels of several types of immune cells, including macrophages, neutrophils, dendritic cells (DCs), B cells, and CD8+ T cells. Additionally, in vitro experiments demonstrated that MEX3A promotes proliferation and migration in OC cells. Taken together, MEX3A might influence the biological functions of OC cells by regulating the immune infiltration in the microenvironment as a prognostic biomarker and a potential therapeutic target.

Oncogenic Potential of the Dual-Function Protein MEX3A

MEX3A belongs to the MEX3 (Muscle EXcess) protein family consisting of four members (MEX3A-D) in humans. Characteristic for MEX3 proteins is their domain structure with 2 HNRNPK homology (KH) domains mediating RNA binding and a C-terminal really interesting new gene (RING) domain that harbors E3 ligase function. In agreement with their domain composition, MEX3 proteins were reported to modulate both RNA fate and protein ubiquitination. MEX3 paralogs exhibit an oncofetal expression pattern, they are severely downregulated postnatally, and re-expression is observed in various malignancies. Enforced expression of MEX3 proteins in various cancers correlates with poor prognosis, emphasizing their oncogenic potential. The latter is supported by MEX3A's impact on proliferation, self-renewal as well as migration of tumor cells in vitro and tumor growth in xenograft studies.

MEX3A suppresses proliferation and EMT via inhibiting Akt signaling pathway in cervical cancer

MEX3A, one member of the human MEX3 gene family, exerts different effects on a variety of human cancer cells. However, the biological functions and regulatory mechanism have not been explored in cervical cancer. In our study, we used multiple approaches to determine the functions and underlying molecular mechanism of MEX3A in cervical tumorigenesis, including CCK-8 assay, BrdU assay, FACS for cell cycle and apoptosis, wound healing assay, Transwell migration and invasion assays, immunohistochemistry (IHC) assay, Transfection, real-time RT-PCR and Western blotting analysis. IHC results showed that the expression levels of MEX3A were decreased in cervical cancer patients with advanced clinical stages and lymph node involvement. Moreover, upregulation of MEX3A attenuated cell proliferation, migration and invasion and induced cell cycle arrest at G0/G1 phase in human cervical cancer cells, whereas knockdown of MEX3A exhibited the opposite effects. Mechanistically, MEX3A exerted its tumor suppressive functions via inactivation of Akt signaling pathway and inhibiting epithelial to mesenchymal transition (EMT). Importantly, Akt activation by its activator SC79 reversed the biological functions of MEX3A overexpression. Furthermore, MEX3A inhibited tumor growth in xenograft models. Overall, our investigation suggested that MEX3A participated in antitumor activity in cervical cancer by inhibition of the Akt signaling pathway and EMT. Hence, targeting MEX3A might have a therapeutic potential to treat cervical cancer.

The effects of MEX3A knockdown on proliferation, apoptosis and migration of osteosarcoma cells

Background

Osteosarcoma is an aggressive malignant tumor which has attracted worldwide attention. MEX3A may be associated with tumors while has not yet seen its coverage on osteosarcoma. Herein, this study was to investigate the correlation between MEX3A and the progression of osteosarcoma.

Methods

Firstly, we determined that expression of MEX3A was significantly higher in osteosarcoma tissues than that in marginal bone by immunohistochemical staining. Additionally, MEX3A expression was downregulated by the RNAi‐mediated knockdown. The functions of MEX3A knockdown on proliferation, apoptosis, cell cycle, migration was assessed by MTT assay, flow cytometry, wound-healing assay and Transwell assay, respectively. Knockdown of MEX3A resulted in suppressing cell proliferation, increasing cell apoptosis, inducing the G2 phase cell cycle arrest, and attenuating cellular migration. Furthermore, mouse xenograft model confirmed inhibitory effects of MEX3A knockdown on osteosarcoma formation.

Results

The preliminary exploration on the molecular mechanism of MEX3A in osteosarcoma cells showed that the induction of apoptosis needs the participation of a series of apoptosis- associated factors, such as upregulation of Caspase 3, Caspase 8 and HSP60, downregulation of HSP27 and XIAP.

Conclusions

In summary, these findings predicated that therapy directed at decreasing MEX3A expression is a potential osteosarcoma treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01882-3.

MEX3A contributes to development and progression of glioma through regulating cell proliferation and cell migration and targeting CCL2

Glioma is one of the most commonly diagnosed intracranial malignant tumors with extremely high morbidity and mortality, whose treatment was seriously limited because of the unclear molecular mechanism. In this study, in order to identify a novel therapeutic target for glioma treatment, we explored the functions and mechanism of MEX3A in regulating glioma. The immunohistochemical staining of MEX3A in glioma and normal tissues revealed the upregulation of MEX3A and further indicated the relationship between high MEX3A expression and higher malignancy as well as poorer prognosis of glioma. In vitro loss-of-function and gain-of-function experiments comprehensively demonstrated that MEX3A may promote glioma development through regulating cell proliferation, cell apoptosis, cell cycle, and cell migration. In vivo experiments also suggested the inhibition of glioma growth by MEX3A knockdown. Moreover, our mechanistic study identifies CCL2 as a potential downstream target of MEX3A, which possesses similar regulatory effects on glioma development with MEX3A and could attenuate the promotion of glioma induced by MEX3A overexpression. Overall, MEX3A was identified as a potential tumor promoter in glioma development and therapeutic target in glioma treatment.

The Role of the RNA-Binding Protein Family MEX-3 in Tumorigenesis

The muscle excess 3 (MEX-3) protein was first identified in Caenorhabditis elegans (C. elegans), and its respective homologues were also observed in vertebrates, including humans. It is a RNA-binding protein (RBP) with an additional ubiquitin E3 ligase function, which further acts as a post-transcriptional repressor through unknown mechanisms. In humans, MEX-3 proteins post-transcriptionally regulate a number of biological processes, including tumor immunological relevant ones. These have been shown to be involved in various diseases, including tumor diseases of distinct origins. This review provides information on the expression and function of the human MEX-3 family in healthy tissues, as well after malignant transformation. Indeed, the MEX-3 expression was shown to be deregulated in several cancers and to affect tumor biological functions, including apoptosis regulation, antigen processing, and presentation, thereby, contributing to the immune evasion of tumor cells. Furthermore, current research suggests MEX-3 proteins as putative markers for prognosis and as novel targets for the anti-cancer treatment.

MEX3A knockdown inhibits the development of pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDA) is one of the most serious causes of death in the world due to its high mortality and inefficacy treatments. MEX3A was first identified in nematodes and was associated with tumor formation and may promote cell proliferation and tumor metastasis. So far, nothing is known about the relationship between MEX3A and PDA.

Methods

In this study, the expression level of MEX3A in PDA tissues was measured by immunohistochemistry. The qRT-PCR and western blot were used to identify the constructed MEX3A knockdown cell lines, which was further used to construct mouse xenotransplantation models. Cell proliferation, colony formation, cell apoptosis and migration were detected by MTT, colony formation, flow cytometry and Transwell.

Results

This study showed that MEX3A expression is significantly upregulated in PDA and associated with tumor grade. Loss-of-function studies showed that downregulation of MEX3A could inhibit cell growth in vitro and in vivo. Moreover, it was demonstrated that knockdown of MEX3A in PDA cells promotes apoptosis by regulating apoptosis-related factors, and inhibits migration through influencing EMT. At the same time, the regulation of PDA progression by MEX3A involves changes in downstream signaling pathways including Akt, p-Akt, PIK3CA, CDK6 and MAPK9.

Conclusions

We proposed that MEX3A is associated with the prognosis and progression of PDA,which can be used as a potential therapeutic target.

The RNA-Binding Ubiquitin Ligase MEX3A Affects Glioblastoma Tumorigenesis by Inducing Ubiquitylation and Degradation of RIG-I

Glioblastoma multiforme (GB) is the most malignant primary brain tumor in humans, with an overall survival of approximatively 15 months. The molecular heterogeneity of GB, as well as its rapid progression, invasiveness and the occurrence of drug-resistant cancer stem cells, limits the efficacy of the current treatments. In order to develop an innovative therapeutic strategy, it is mandatory to identify and characterize new molecular players responsible for the GB malignant phenotype. In this study, the RNA-binding ubiquitin ligase MEX3A was selected from a gene expression analysis performed on publicly available datasets, to assess its biological and still-unknown activity in GB tumorigenesis. We find that MEX3A is strongly up-regulated in GB specimens, and this correlates with very low protein levels of RIG-I, a tumor suppressor involved in differentiation, apoptosis and innate immune response. We demonstrate that MEX3A binds RIG-I and induces its ubiquitylation and proteasome-dependent degradation. Further, the genetic depletion of MEX3A leads to an increase of RIG-I protein levels and results in the suppression of GB cell growth. Our findings unveil a novel molecular mechanism involved in GB tumorigenesis and suggest MEX3A and RIG-I as promising therapeutic targets in GB.

Clinical characteristics and prognostic value of MEX3A mRNA in liver cancer

BACKGROUND

MEX3A is an RNA-binding proteins (RBPs) that promotes the proliferation, invasion, migration and viability of cancer cells. The aim of this study was to explore the clinicopathological characteristics and prognostic significance of MEX3A mRNA expression in liver cancer.

METHODS

RNA-Seq and clinical data were collected from The Cancer Genome Atlas (TCGA). Boxplots were used to represent discrete variables of MEX3A. Chi-square tests were used to analyze the correlation between clinical features and MEX3A expression. Receiver operating characteristic (ROC) curves were used to confirm diagnostic ability. Independent prognostic ability and values were assessed using Kaplan-Meier curves and Cox analysis.

RESULTS

We acquired MEX3A RNA-Seq from 50 normal liver tissues and 373 liver cancer patients along with clinical data. We found that MEX3A was up-regulated in liver cancer which increased according to histological grade (p < 0.001). MEX3A showed moderate diagnostic ability for liver cancer (AUC = 0.837). Kaplan-Meier curves and Cox analysis revealed that the high expression of MEX3A was significantly associated with poor survival (OS and RFS) (p < 0.001). Moreover, MEX3A was identified as an independent prognostic factor of liver cancer (p < 0.001).

CONCLUSIONS

MEX3A expression shows promise as an independent predictor of liver cancer prognosis.