The miR-503 cluster is coordinately under-expressed in endometrial endometrioid adenocarcinoma and targets many oncogenes, cell cycle genes, DNA repair genes and chemotherapy response genes

A C->T Variation in 3'-Untranslated Region Elevates MED12 Protein Level in Breast Cancer That Relates to Better Prognosis

Objective: Mediator complex subunit 12 (MED12) is among the most frequently mutated genes in various types of human cancers. However, there is still a lack of understanding regarding the role of MED12 in breast cancer patient. Therefore, the aim of this study is to explore the roles of MED12 in breast cancer. Materials and Methods: We utilized the UALCAN platform (http://ualcan.path.uab.edu/) for analyzing the transcriptional expression, protein expression, and protein phosphorylation data of MED12. Our study involved 35 breast cancer patients. From these samples, we extracted proteins and RNA. To obtain the sequence of MED12 3'-UTR, we performed reverse transcription-polymerase chain reaction and sequencing. We then used TargetScan to predict the miRNA targets of MED12 3'-UTR and confirmed the interactions between miRNAs and MED12 3'-UTR through dual luciferase assay. Results: The protein level of MED12 was upregulated in breast cancer, while the mRNA level did not show significant changes. Interestingly, higher levels of MED12 mRNA were associated with better prognosis, whereas patients with increased MED12 protein levels tended to have a poorer prognosis. Furthermore, through our analysis of the MED12 3'-UTR sequence, we identified a specific C->T variation that was unique to breast tumors. We also identified four miRNAs (miR-204, -211, -450 b, and -518a) that directly target MED12 3'-UTR. Most important, this C->T variation disrupts the interaction between MED12 3'-UTR and miR-450b, ultimately leading to the upregulation of MED12 in breast cancer. Conclusion: Our study revealed a significant finding regarding a mutation site in the MED12 3'-UTR that contributes to the upregulation of MED12 in breast cancer. This mutation disrupts the interactions between specific miRNAs and MED12 mRNA, leading to increased expression of MED12. These findings have important implications for breast cancer diagnosis, as this mutation site can serve as a potent biomarker.

The interplay of sex steroid hormones and microRNAs in endometrial cancer: current understanding and future directions

Introduction

Endometrial cancer is a hormone-dependent malignancy, and sex steroid hormones play a crucial role in its pathogenesis. Recent studies have demonstrated that microRNAs (miRNAs) can regulate the expression of sex steroid hormone receptors and modulate hormone signaling pathways. Our aim is to provide an overview of the current understanding of the role of miRNAs in endometrial cancer regulated by sex steroid hormone pathways.

Methods

A thorough literature search was carried out in the PubMed database. The articles published from 2018 to the present were included. Keywords related to miRNAs, endometrial cancer, and sex steroid hormones were used in the search.

Results

Dysregulation of miRNAs has been linked to abnormal sex steroid hormone signaling and the development of endometrial cancer. Various miRNAs have been identified as modulators of estrogen and progesterone receptor expression, and the miRNA expression profile has been shown to be a predictor of response to hormone therapy. Additionally, specific miRNAs have been implicated in the regulation of genes involved in hormone-related signaling pathways, such as the PI3K/Akt/mTOR and MAPK/ERK pathways.

Conclusion

The regulation of sex steroid hormones by miRNAs is a promising area of research in endometrial cancer. Future studies should focus on elucidating the functional roles of specific miRNAs in sex steroid hormone signaling and identifying novel miRNA targets for hormone therapy in endometrial cancer management.

Human umbilical cord blood mesenchymal stem cells-derived exosomal microRNA-503-3p inhibits progression of human endometrial cancer cells through downregulating MEST

Endometrial cancer (EC) is a group of epithelial malignant tumors that occur in the endometrium. The specific pathogenesis is not revealed, hence, the goal of this study was to investigate the influence of human umbilical cord blood mesenchymal stem cells (hUMSCs)-derived exosomal microRNA-503-3p (miR-503-3p) on human EC cells by mediating mesoderm-specific transcript (MEST). The binding relationship between MiR-503-3p and MEST was searched. HUMSCs were collected and exosomes (Exos) were isolated and identified. Human EC cell lines HEC-1B and RL95-2 were transfected with elevated miR-503-3p or silenced MEST vector or co-cultured with Exos to figure their roles in biological functions of EC cells. The in vitro effect of miR-503-3p, MEST, and Exos on EC cells was further verified in vivo. MEST was a target of miR-503-3p. Overexpression of miR-503-3p or reduction of MEST suppressed the biological functions of EC cells. Enhanced MEST expression mitigated the role of upregulated miR-503-3p on the growth of EC cells. HUMSCs-derived Exos suppressed EC cell growth, upregulated miR-503-3p-modified HUMSCs-derived Exos had a more obvious inhibitory effect on EC cell growth. The anti-tumor effect of elevated miR-503-3p, silenced MEST, and HUMSCs-derived Exos were verified in nude mice. This study highlights that hUMSCs-derived exosomal miR-503-3p inhibits EC development by suppressing MEST, which is of great benefit to EC therapy.

Construction of miRNA-mRNA Regulatory Network and Prognostic Signature in Endometrial Cancer

Introduction

This bioinformatic study confirmed a new miRNA-mRNA regulatory network and a prognostic signature in endometrial cancer (EC).

Materials and Methods

We downloaded RNA-seq and miRNA-seq data of EC from the TCGA database, then used EdegR package to screen differentially expressed miRNAs and mRNAs (DE-miRNAs and DE-mRNAs). Then, we constructed a regulatory network of EC-associated miRNAs and hub genes by Cytoscape, and determined the expression of unexplored miRNAs in EC tissues and normal adjacent tissues by quantitative Real-Time PCR (qRT-PCR). A prognostic signature model and a predictive nomogram were constructed. Finally, we explored the association between the prognostic model and the immune cell infiltration.

Results

A total of 11,531 DE-mRNAs and 236 DE-miRNAs, as well as 275 and 118 candidate DEGs for upregulated and downregulated DE-miRNAs were screened out. The miRNA-mRNA network included 5 downregulated and 13 upregulated DE-miRNAs. qRT-PCR proved that the expression levels of miRNA-18a-5p, miRNA-18b-5p, miRNA-449c-5p and miRNA-1224-5p and their target genes (NR3C1, CTGF, MYC, and TNS1) were consistent with our predictions. Univariate and multivariate Cox proportional hazards regression analyses of the hub genes revealed a significant prognostic value of NR3C1, EZH2, AND GATA4, and these genes were closely related to eight types of immune infiltration cells.

Conclusion

We identified three genes as candidate biomarkers for EC, which may provide a theoretical basis for targeted therapy.

Epigenetic Regulation of MicroRNA Clusters and Families during Tumor Development

MicroRNAs are small non-coding single-stranded RNA molecules regulating gene expression on a post-transcriptional level based on the seed sequence similarity. They are frequently clustered; thus, they are either simultaneously transcribed into a single polycistronic transcript or they may be transcribed independently. Importantly, microRNA families that contain the same seed region and thus target related signaling proteins, may be localized in one or more clusters, which are in a close relationship. MicroRNAs are involved in basic physiological processes, and their deregulation is associated with the origin of various pathologies, including solid tumors or hematologic malignancies. Recently, the interplay between the expression of microRNA clusters and families and epigenetic machinery was described, indicating aberrant DNA methylation or histone modifications as major mechanisms responsible for microRNA deregulation during cancerogenesis. In this review, the most studied microRNA clusters and families affected by hyper- or hypomethylation as well as by histone modifications are presented with the focus on particular mechanisms. Finally, the diagnostic and prognostic potential of microRNA clusters and families is discussed together with technologies currently used for epigenetic-based cancer therapies.

MicroRNAs in porcine uterus and serum are affected by zearalenone and represent a new target for mycotoxin biomarker discovery

The mycotoxin zearalenone (ZEN) poses a risk to animal health because of its estrogenic effects. Diagnosis of ZEN-induced disorders remains challenging due to the lack of appropriate biomarkers. In this regard, circulating microRNAs (small non-coding RNAs) have remarkable potential, as they can serve as indicators for pathological processes in tissue. Thus, we combined untargeted and targeted transcriptomics approaches to investigate the effects of ZEN on the microRNA expression in porcine uterus, jejunum and serum, respectively. To this end, twenty-four piglets received uncontaminated feed (Control) or feed containing 0.17 mg/kg ZEN (ZEN low), 1.46 mg/kg ZEN (ZEN medium) and 4.58 mg/kg ZEN (ZEN high). After 28 days, the microRNA expression in the jejunum remained unaffected, while significant changes in the uterine microRNA profile were observed. Importantly, 14 microRNAs were commonly and dose-dependently affected in both the ZEN medium and ZEN high group, including microRNAs from the miR-503 cluster (i.e. ssc-miR-424-5p, ssc-miR-450a, ssc-miR-450b-5p, ssc-miR-450c-5p, ssc-miR-503 and ssc-miR-542-3p). Predicted target genes for those microRNAs are associated with regulation of gene expression and signal transduction (e.g. cell cycle). Although the effects in serum were less pronounced, receiver operating characteristic analysis revealed that several microRNA ratios were able to discriminate properly between non-exposed and ZEN-exposed pigs (e.g. ssc-miR-135a-5p/ssc-miR-432-5p, ssc-miR-542-3p/ssc-miR-493-3p). This work sheds new light on the molecular mechanisms of ZEN, and fosters biomarker discovery.

miR-148-3p Inhibits Growth of Glioblastoma Targeting DNA Methyltransferase-1 (DNMT1)

To date, miR-148-3p and DNMT1–recombinant human runt-related transcription factor 3 (RUNX3) axis have been linked to cell proliferation, migration, and invasion; however, their roles and relationships in human glioblastoma multiforme (GBM) are still not clear. Here we found that the expression of miR-148-3p in glioma tissues was decreased compared with adjacent nontumor tissues and correlated with WHO grade, tumor size, and prognosis as well as DNMT1 and RUNX3 expressions. Compared with NHA cells, the expression of miR-148-3p in U87 and U251 cells was also downregulated and accompanied with upregulation of DNMT1 and hypermethylation level of RUNX3 promoter region. miR-148-3p overexpression induced apoptosis and cell cycle arrest of U87 and U251 cells, and affected cell migration and invasion. miR-148-3p mimics effectively suppressed the expression of DNMT1 and methylation of RUNX3 promoter, finally upregulating RUNX3 expression. Mechanistically, the 3′-untranslated region (3′-UTR) of DNMT1 was a direct target of miR-148-3p. Overexpression of miR-148-3p or inhibition of DNMT1 induced the expression of E-cadherin and reduced the expressions of N-cadherin, vimentin, MMP-2, and MMP-9. In conclusion, miR-148-3p directly repressed the expression of DNMT1 and inhibited proliferation, migration, and invasion by regulating DNMT1–RUNX3 axis and the epithelial–mesenchymal transition in GBM. Our findings provide a new foundation for treatment of patients with GBM.