lncRNA MEG3 inhibits pituitary tumor development by participating in cell proliferation, apoptosis and EMT processes

Recent advances of miR-23 in human diseases and growth development

MicroRNA (miRNA) is broadly manifested in eukaryotes and serves as a critical function in biological development and disease occurrence. With the rapid advancement of experimental research tools, researchers have discovered functional correlations among different miRNA isoforms and clusters within the same miRNA family. As a highly conserved member in the miR-23-27-24 cluster, miR-23 exhibits different isoforms and participates in various essential development. Although the miR-23-27-24 cluster has overlapping target sites, their differential expression can demonstrate independent biological functions. Furthermore, the untapped effects of miR-23 on organisms, whether as a functional cluster or a single regulator, has not been systematically elucidated yet. In this review article, we analyze the genomic location of miR-23 and its sequence variances among its isoforms or family members while summarizing its regulatory functions in metabolic diseases, immune responses, cardiovascular diseases, cancer, organ development as well as nervous system function. This review highlights the significant role of miR-23 as a biomarker for disease diagnosis and a key regulatory factor in pathogenesis, which can help us comprehend the diverse functions of miRNAs and provide a theoretical reference for the functional differences among miRNA isoforms.

Silencing of maternally expressed RNAs in Dlk1-Dio3 domain causes fatal vascular injury in the fetal liver

The mammalian imprinted Dlk1-Dio3 domain contains multiple lncRNAs, mRNAs, the largest miRNA cluster in the genome and four differentially methylated regions (DMRs), and deletion of maternally expressed RNA within this locus results in embryonic lethality, but the mechanism by which this occurs is not clear. Here, we optimized the model of maternally expressed RNAs transcription termination in the domain and found that the cause of embryonic death was apoptosis in the embryo, particularly in the liver. We generated a mouse model of maternally expressed RNAs silencing in the Dlk1-Dio3 domain by inserting a 3 × polyA termination sequence into the Gtl2 locus. By analyzing RNA-seq data of mouse embryos combined with histological analysis, we found that silencing of maternally expressed RNAs in the domain activated apoptosis, causing vascular rupture of the fetal liver, resulting in hemorrhage and injury. Mechanistically, termination of Gtl2 transcription results in the silencing of maternally expressed RNAs and activation of paternally expressed genes in the interval, and it is the gene itself rather than the IG-DMR and Gtl2-DMR that causes the aforementioned phenotypes. In conclusion, these findings illuminate a novel mechanism by which the silencing of maternally expressed RNAs within Dlk1-Dio3 domain leads to hepatic hemorrhage and embryonic death through the activation of apoptosis.

Identification of a novel histone acetylation-related long non-coding RNA model combined with qRT-PCR experiments for prognosis and therapy in gastric cancer

Gastric cancer (GC) is considered a global health crisis due to the scarcity of early diagnostic methods. Numerous studies have substantiated the involvement of histone acetylation imbalance in the progression of diverse tumor types. The potential roles of long non-coding RNA (lncRNA) in improving prognostic, predictive as well as therapeutic approaches in cancers have made it a major hotspot in recent years. Nevertheless, existent studies have never concerned the prognostic and clinical value of histone acetylation-related lncRNAs (HARlncs) in GC. Based on the aforementioned rationale, we developed a prognostic model incorporating four HARlncs-AC114730.1, AL445250.1, LINC01778, and AL163953.1-which demonstrated potential as an independent predictor of prognosis. Subsequently, GC patients were stratified into high-risk and low-risk groups. The low-risk group exhibited significantly higher overall survival (OS) compared to the high-risk group. Based on the analyses of the tumor microenvironment (TME) and immune responses, significant differences were observed between the two risk groups in terms of immune cell infiltration, immune checkpoint (ICP) expression, and other TME alterations. Furthermore, the sensitivity of GC patients to some chemotherapeutic drugs and the discrepant biological behaviors of three tumor clusters were studied in this model. In summary, we developed an effective HARlncs model with the objective of offering novel prognostic prediction methods and identifying potential therapeutic targets for GC patients.

LncRNA MEG3 Inhibits the Epithelial-mesenchymal Transition of Bladder Cancer Cells through the Snail/E-cadherin Axis

OBJECTIVE

This study aimed to investigate the role of the long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) in the epithelial-mesenchymal transition (EMT) of bladder cancer cells and the potential mechanisms.

METHODS

Cell invasion, migration, and wound healing assays were conducted to assess the effects of MEG3 on the invasive and migratory capabilities of bladder cancer cells. The expression levels of E-cadherin were measured using Western blotting, RT-qPCR, and dual luciferase reporter assays. RNA immunoprecipitation and pull-down assays were performed to investigate the interactions between MEG3 and its downstream targets.

RESULTS

MEG3 suppressed the invasion and migration of bladder cancer cells and modulated the transcription of E-cadherin. The binding of MEG3 to the zinc finger region of the transcription factor Snail prevented its ability to transcriptionally repress E-cadherin. Additionally, MEG3 suppressed the phosphorylation of extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and P38, thereby decreasing the expression of Snail and stimulating the expression of E-cadherin.

CONCLUSION

MEG3 plays a vital role in suppressing the EMT in bladder cancer cells, indicating its potential as a promising therapeutic target for the treatment of bladder cancer.

Expression analysis of necroptosis related genes and lncRNAs in patients with pituitary neuroendocrine tumors

Necroptosis can either be the cause of tumorigenesis or it can impede its process. Recently, it has been proved that long non-coding RNAs (lncRNAs) have different crucial roles at cellular level, especially on cell death. Regarding the important role of necroptosis and lncRNAs in the pathogenesis of different cancers, especially pituitary adenomas (PAs), we assessed expression levels of two necroptosis related genes, namely TRADD and BIRC2, in addition to three related lncRNAs, namely FLVCR1-DT, MAGI2-AS3, and NEAT1 in PAs compared with adjacent normal tissues (ANTs). TRADD had no significant difference between two groups; however, BIRC2, FLVCR1-DT, MAGI2-AS3, and NEAT1 were upregulated in PAs compared to ANTs (Expression ratios [95% CI] = 2.3 [1.47-3.6], 2.13 [1.02-4.44], 3.01 [1.76-5.16] and 2.47 [1.37-4.45], respectively). When taking into account different types of PAs, significant upregulation of BIRC2, MAGI2-AS3 and NEAT1 was recorded in non-functioning PAs compared with corresponding ANTs (Expression ratios [95% CI] =1.9 [1.04-3.43], 2.69 [1.26-5.72] and 2.22 [0.98-5.01], respectively). Additionally, higher levels of BIRC2 were associated with higher flow of CSF (P value=0.048). Moreover, higher Knosp classified tumors had lower levels of BIRC2 (P value=0.001). Finally, lower levels of MAGI2-AS3 were associated with larger tumor size (P value=0.006). NEAT1 expression was correlated with FLVCR1-DT and TRADD. TRADD expression was correlated with FLVCR1-DT. Additional correlation was observed between expression of BIRC2 and MAGI2-AS3. In sum, this study provides evidence that dysregulated levels of studied genes could contribute to the pathogenesis of pituitary tumors.

Interplay between lncRNA/miRNA and Wnt/ß-catenin signaling in brain cancer tumorigenesis

Brain cancers are among the most aggressive malignancies with high mortality and morbidity worldwide. The pathogenesis of brain cancers is a very complicated process involving various genetic mutations affecting several oncogenic signaling pathways like Wnt/β-catenin axis. Uncontrolled activation of this oncogenic signaling is associated with decreased survival rate and poor prognosis in cancer patients. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) were shown to play important roles in regulating cell proliferation, differentiation, and apoptosis by regulating the expression of their target genes. Aberrant expression of these non-coding RNAs (ncRNAs) was reported in many human cancers, including glioblastoma, medulloblastoma, meningioma, and pituitary adenoma. Multiple lncRNAs were shown to participate in brain tumor pathogenesis by targeting Wnt signaling regulatory miRNAs. SNHG7/miR-5095, PCAT6/miR-139-3p, SNHG6/miR-944, SNHG1/ miR-556-5p, SNHG17/ miR-506-3p, LINC00702/miR-4652-3p, DLGAP1-AS1/miR-515-5p, HOTAIR/miR-1, HOTAIR/miR-206, CRNDE/miR-29c-3p, AGAP2-AS1/ miR-15a/b-5p, CLRN1-AS1/miR-217, MEG3/miR-23b-3p, and GAS5/miR-27a-5p are identified lncRNA/miRNA pairs that are involved in this process. Therefore, recognition of the expression profile and regulatory role of ncRNAs on the Wnt signaling may offer a novel approach to the diagnosis, prognosis, and treatment of human cancers. This review summarizes previous data on the modulatory role of lncRNAs/miRNAs on the Wnt/β-catenin pathway implicated in tumor growth, EMT, metastasis, and chemoresistance in brain cancers.

Regulation of long noncoding RNAs in the pathogenesis and clinical implications of pituitary adenomas

BACKGROUND

Pituitary adenoma (PA) is a type of tumor that develops in the sella turcica and is one of the most frequent intracranial tumors. It belongs to a type of adenoma derived from a single clone of cells in the pituitary gland. PA ranks third among all intracranial tumors, following only gliomas and meningioma. The average prevalence rate is approximately 15% at autopsy and 22.5% at radiological examinations.

OBJECTIVE AND SIGNIFICANCE

Most PAs are benign and non-invasive adenomas that can be removed surgically or controlled with medication. However, approximately 35% of them show invasion into nearby anatomical structures and cannot be completely resected. 0.1%~0.2% of PA cases eventually develop into pituitary carcinomas. Additionally, PA may cause severe morbidity due to mass effects and the disorder of pituitary hormone secretion. Therefore, there is an urgent need to clarify the pathological mechanism of PA, improve the accuracy of diagnosis, and develop targeted therapies.

RESEARCH STATUS

Although current knowledge about the pathogenesis of PA remains limited, epigenetic modulation of PA has been increasingly implicated. Long non-coding RNAs (lncRNAs) are known to regulate gene expression post-transcriptionally and exert substantial roles in the initiation, progression, or suppression of various tumors. Accumulating evidence has shown close relationships between lncRNA dysregulation and PA development.

CONCLUSIONS

This review highlights recent progress in the study of lncRNAs in PA pathogenesis and their potential as diagnostic/prognostic biomarkers or therapeutic targets for PA patients.

LncRNA MEG3: Potential stock for precision treatment of cardiovascular diseases

The prevalence and mortality rates of cardiovascular diseases are increasing, and new treatment strategies are urgently needed. From the perspective of basic pathogenesis, the occurrence and development of cardiovascular diseases are related to inflammation, apoptosis, fibrosis and autophagy of cardiomyocytes, endothelial cells and other related cells. The involvement of maternally expressed gene 3 (MEG3) in human disease processes has been increasingly reported. P53 and PI3K/Akt are important pathways by which MEG3 participates in regulating cell apoptosis. MEG3 directly or competitively binds with miRNA to participate in apoptosis, inflammation, oxidative stress, endoplasmic reticulum stress, EMT and other processes. LncRNA MEG3 is mainly involved in malignant tumors, metabolic diseases, immune system diseases, cardiovascular and cerebrovascular diseases, etc., LncRNA MEG3 has a variety of pathological effects in cardiomyocytes, fibroblasts and endothelial cells and has great clinical application potential in the prevention and treatment of AS, MIRI, hypertension and HF. This paper will review the research progress of MEG3 in the aspects of mechanism of action, other systemic diseases and cardiovascular diseases, and point out its great potential in the prevention and treatment of cardiovascular diseases. lncRNAs also play a role in endothelial cells. In addition, lncRNA MEG3 has shown biomarker value, prognostic value and therapeutic response measurement in tumor diseases. We boldly speculate that MEG3 will play a role in the emerging discipline of tumor heart disease.

Emerging Roles of miRNA, lncRNA, circRNA, and Their Cross-Talk in Pituitary Adenoma

Pituitary adenoma (PA) is a common intracranial tumor without specific biomarkers for diagnosis and treatment. Non-coding RNAs (ncRNAs), including microRNAs (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA), regulate a variety of cellular processes, such as cell proliferation, differentiation, and apoptosis. Increasing studies have shown that the dysregulation of ncRNAs, especially the cross-talk between lncRNA/circRNA and miRNA, is related to the pathogenesis, diagnosis, and prognosis of PA. Therefore, ncRNAs can be considered as promising biomarkers for PA. In this review, we summarize the roles of ncRNAs from different specimens (i.e., tissues, biofluids, cells, and exosomes) in multiple subtypes of PA and highlight important advances in understanding the contribution of the cross-talk between ncRNAs (e.g., competing endogenous RNAs) to PA disease.

The Long Noncoding RNA MEG3 Retains Epithelial-Mesenchymal Transition by Sponging miR-146b-5p to Regulate SLFN5 Expression in Breast Cancer Cells

More and more studies have shown that long noncoding RNAs (lncRNAs) play essential roles in malignant tumors. The lncRNA MEG3 serves as a crucial molecule in breast cancer development, but the specific molecular mechanism needs to be further explored. We previously reported that Schlafen family member 5 (SLFN5) inhibits breast cancer malignant development by regulating epithelial-mesenchymal transition (EMT), invasion, and proliferation/apoptosis. Herein, we demonstrated that MEG3 was downregulated in pan-cancers and correlated with SLFN5 expression positively in breast cancer by bioinformatics analysis of TCGA and UCSC Xena data. Intervention with MEG3 positively affected SLFN5 expression in breast cancer cells. MEG3 repressed EMT and migration/invasion, similar to our previously reported functions of SLFN5 in breast cancer. Through bioinformatics analysis of starBase and LncBase data, 12 miRNAs were found to regulate both SLFN5 and MEG3, in which miR-146b-5p was confirmed to be regulated by MEG3 using MEG3 siRNA and overexpression method. MiR-146b-5p could bind to both SLFN5 3′UTR and MEG3, and inhibit their expression in a competing endogenous RNA mechanism, assayed by luciferase reporter and RNA pull down methods. Therefore, we conclude that MEG3 positively modulates SLFN5 expression by sponging miR-146b-5p and inhibits breast cancer development.

The FOXO family of transcription factors: key molecular players in gastric cancer

Gastric cancer (GC) is the fifth most frequently diagnosed cancer worldwide and the third leading cause of cancer-related death with an oncological origin. Despite its decline in incidence and mortality in recent years, GC remains a global public problem that seriously threatens patients' health and lives. The forkhead box O proteins (FOXOs) are a family of evolutionarily conserved transcription factors (TFs) with crucial roles in cell fate decisions. In mammals, the FOXO family consists of four members FOXO1, 3a, 4, and 6. FOXOs play crucial roles in a variety of biological processes, such as development, metabolism, and stem cell maintenance, by regulating the expression of their target genes in space and time. An accumulating amount of evidence has shown that the dysregulation of FOXOs is involved in GC progression by affecting multiple cellular processes, including proliferation, apoptosis, invasion, metastasis, cell cycle progression, carcinogenesis, and resistance to chemotherapeutic drugs. In this review, we systematically summarize the recent findings on the regulatory mechanisms of FOXO family expression and activity and elucidate its roles in GC progression. Moreover, we also highlight the clinical implications of FOXOs in GC treatment.

Recent advancements in the molecular biology of pituitary adenomas

INTRODUCTION

Pituitary adenomas are a common and diverse group of intracranial tumors arising from the anterior pituitary that are usually slow-growing and benign, but still pose a significant healthcare burden to patients. Additionally, they are increasing in both incidence and prevalence, leading to a need for better understanding of molecular changes in the development of these tumors.

AREAS COVERED

A PubMed literature search was conducted using the terms 'pituitary adenoma' in combination with keywords related to secretory subtype: lactotroph, somatotroph, corticotroph, gonadotroph and null cell, in addition to their transcription factor expression: PIT1, TPIT, and SF-1. Articles resulting from this search were analyzed, as well as relevant articles cited as their references. In this review, we highlight recent advances in the genetic and epigenetic characterization of individual pituitary adenoma subtypes and the effect it may have on guiding future clinical treatment of these tumors.

EXPERT OPINION

Understanding the molecular biology of pituitary adenomas is a fundamental step toward advancing the treatment of these tumors. Yet crucial knowledge gaps exist in our understanding of the underlying molecular biology of pituitary adenomas which can potentially be addressed by turning to differentially activated molecular pathways in tumor relative to normal gland.

LncRNA HLA-F-AS1 Enhances the Migration, Invasion and Apoptosis of Glioblastoma Cells by Targeting lncRNA MEG3

Background

Previous studies revealed the oncogenic role of long non-coding RNA (lncRNA) HLA-F-AS1 in colon cancer and breast cancer, while its role in other cancers is unclear. We predicted the direct interaction between HLA-F-AS1 and MEG3, which is a tumor suppressor lncRNA. We then assessed the interaction between HLA-F-AS1 and MEG3 in glioblastoma (GBM).

Methods

The expression levels of HLA-F-AS1 and MEG3 in GBM and paired non-tumor tissues from 60 GBM patients were analyzed by RT-qPCR. Overexpression of HLA-F-AS1 and MEG3 was achieved in GBM cells to explore the interaction between them. The direct interaction between them was confirmed by RNA pull-down assay. The roles of HLA-F-AS1 and MEG3 in cell invasion, migration and apoptosis were explored by Transwell assays and cell apoptosis assay.

Results

HLA-F-AS1 was highly expressed, and MEG3 was downregulated in GBM. Overexpression of HLA-F-AS1 reduced the expression levels of MEG3 while overexpression of MEG3 did not alter the expression of HLA-F-AS1. HLA-F-AS1 increased cell migration and invasion, but decreased cell apoptosis. MEG3 played opposite roles and reduced the effects of HLA-F-AS1 on cell behaviors.

Conclusion

HLA-F-AS1 may sponge MEG3 in GBM cells to promote cell invasion and migration, and to suppress cell apoptosis.

The Emerging Role of Non-Coding RNAs in Pituitary Gland Tumors and Meningioma

Long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are non-coding transcripts which are involved in the pathogenesis of pituitary gland tumors. LncRNAs that participate in the pathogenesis of pituitary gland tumors mainly serve as sponges for miRNAs. CLRN1-AS1/miR-217, XIST/miR-424-5p, H19/miR-93a, LINC00473/miR-502-3p, SNHG7/miR-449a, MEG8/miR-454-3p, MEG3/miR-23b-3p, MEG3/miR-376B-3P, SNHG6/miR-944, PCAT6/miR-139-3p, lncRNA-m433s1/miR-433, TUG1/miR-187-3p, SNHG1/miR-187-3p, SNHG1/miR-302, SNHG1/miR-372, SNHG1/miR-373, and SNHG1/miR-520 are identified lncRNA/miRNA pairs that are involved in this process. Hsa_circ_0001368 and circOMA1 are two examples of circRNAs that contribute to the pathogenesis of pituitary gland tumors. Meanwhile, SNHG1, LINC00702, LINC00460, and MEG3 have been found to partake in the pathogenesis of meningioma. In the current review, we describe the role of non-coding RNAs in two types of brain tumors, i.e., pituitary tumors and meningioma.