Tumor suppression by MEG3 lncRNA in a human pituitary tumor derived cell line

Non-coding RNAs and exosomal non-coding RNAs in pituitary adenoma

Pituitary adenoma (PA) is the third most common primary intracranial tumor in terms of overall disease incidence. Although they are benign tumors, they can have a variety of clinical symptoms, but are mostly asymptomatic, which often leads to diagnosis at an advanced stage when surgical intervention is ineffective. Earlier identification of PA could reduce morbidity and allow better clinical management of the affected patients. Non-coding RNAs (ncRNAs) do not generally code for proteins, but can modulate biological processes at the post-transcriptional level through a variety of molecular mechanisms. An increased number of ncRNA expression profiles have been found in PAs. Therefore, understanding the expression patterns of different ncRNAs could be a promising method for developing non-invasive biomarkers. This review summarizes the expression patterns of dysregulated ncRNAs (microRNAs, long non-coding RNAs, and circular RNAs) involved in PA, which could one day serve as innovative biomarkers or therapeutic targets for the treatment of this neoplasia. We also discuss the potential molecular pathways by which the dysregulated ncRNAs could cause PA and affect its progression.

Hypoxia-induced long non-coding RNA plasmacytoma variant translocation 1 upregulation aggravates pulmonary arterial smooth muscle cell proliferation by regulating autophagy via miR-186/Srf/Ctgf and miR-26b/Ctgf signaling pathways

BACKGROUND

The lncRNA PVT1 reportedly functions as a competing endogenous RNA (ceRNA) of miR-186 and miR-26b in different tissue types. In this study, we investigated the possible involvement of the miR-186/Srf/Ctgf and miR-26b/Ctgf signaling pathways in the pathogenesis of hypoxia-induced PAH.

METHODS

Expression of PVT1, miR-186, miR-26b, and Srf and Ctgf mRNAs were evaluated by real-time polymerase chain reaction. Protein expression of SRF, CTGF, LC3B-I, LC3B-II, and Beclin-I was evaluated using western blotting. The regulatory relationship between the lncRNA, miRNAs, and target mRNAs was explored using luciferase assays. Immunohistochemistry was used to evaluate the expression of SRF and CTGF in situ. MTT assay was performed to assess the proliferation of PASMCs.

RESULTS

Exposure to hypoxia markedly altered the expression of PVT1, Srf, Ctgf, miR-186, and miR-26b in a rat model. MiR-186 binding sites in the sequences of Srf mRNA and PVT1 were confirmed by luciferase assays, indicating that miR-186 may interact with both PVT1 and Srf mRNA. Additionally, miR-26b binding sites were identified in the sequences of Ctgf mRNA and PVT1, suggesting that miR-26b may interact with both PVT1 and Ctgf mRNA. In line with this, we found that overexpression of PVT1 reduced expression of miR-26b and miR-186 but activated expression of Srf, Ctgf, LC3B-II, and Beclin-I.

CONCLUSIONS

Upregulation of PVT1 by exposure to hypoxia promoted the expression of CTGF, leading to deregulation of autophagy and abnormal proliferation of PASMCs. Dysregulation of the miR-186/Srf/Ctgf and miR-26b/Ctgf signaling pathways may be involved in the pathogenesis of hypoxia-induced PASMCs.

Mice With RIP-Cre-mediated Deletion of the Long Noncoding RNA Meg3 Show Normal Pancreatic Islets and Enlarged Pituitary

Context

Maternally expressed gene 3 (MEG3) is a long noncoding RNA (lncRNA) that has been implicated as a tumor suppressor.

Objective

The expression of MEG3 RNA is downregulated in various human tumors, including pituitary adenoma and pancreatic islet tumors due to MEG3 gene deletion or DNA hypermethylation. Mouse models with conventional germline deletion of Meg3 have shown that Meg3 is essential for perinatal or postnatal development and survival. However, a direct role of Meg3 loss in tumorigenesis has not been shown.

Methods

To observe a causal relationship between Meg3 loss and tumorigenesis, we have generated a mouse model with conditional deletion of Meg3 mediated by the RIP-Cre transgene that initiated Meg3 deletion in pancreatic islet β cells and anterior pituitary.

Results

Meg3 loss did not lead to the development of islet tumors. Interestingly, RIP-Cre-mediated Meg3 loss led to the development of an enlarged pituitary. The genes in the Meg3 region are transcribed together as a 210 kb RNA that is processed into Meg3 and other transcripts. Whether these tandem transcripts play a functional role in the growth of pancreatic endocrine cells and pituitary cells remains to be determined.

Conclusion

Our mouse model shows that Meg3 loss leads to hyperplasia in the pituitary and not in pancreatic islets, thus serving as a valuable model to study pathways associated with pituitary cell proliferation and function. Future mouse models with specific inactivation of Meg3 alone or other transcripts in the Meg3 polycistron are warranted to study tissue-specific effects on initiating neoplasia and tumor development.

ST8SIA6-AS1 Promotes the Epithelial-to-Mesenchymal Transition and Angiogenesis of Pituitary Adenoma

To investigate the effect of long noncoding RNA ST8SIA6-AS1 on the epithelial-to-mesenchymal transition (EMT) and angiogenesis of pituitary adenoma and its possible mechanism. The expression levels of ST8SIA6-AS1 and HOXA9 in noninvasive pituitary adenoma and invasive pituitary adenoma were detected using qRT-PCR. sh-ST8SIA6-AS1 transfection silenced the expression of ST8SIA6-AS1 in GH3 and GTI-1 cells. The effects of ST8SIA6-AS1 on the proliferation, invasion, angiogenesis, and EMT of GH3 and GTI-1 pituitary adenoma cells were detected. The migration ability of cells was detected through scratch assay. Dual luciferase analysis verified the targeting relationship between ST8SIA6-AS1 and miR-5195-3p. ST8SIA6-AS1 and HOXA9 were highly expressed in invasive pituitary adenoma. In pituitary adenomas, miR-5195-3p directly targeted HOXA9. miR-5195-3p is the target gene of ST8SIA6-AS1. ST8SIA6-AS1 knockdown inhibited the proliferation, invasion, angiogenesis, and EMT of pituitary adenoma. HOXA9 expression mediates the biological effect of ST8SIA6-AS1. ST8SIA6-AS1 targets miR-5195-3p to regulate the expression of HOXA9 and promote the EMT of pituitary adenomas.

An Exploration of Non-Coding RNAs in Extracellular Vesicles Delivered by Swine Anterior Pituitary

Extracellular vesicles are lipid bilayer-delimited particles carrying proteins, lipids, and small RNAs. Previous studies have demonstrated that they had regulatory functions both physiologically and pathologically. However, information remains inadequate on extracellular vesicles from the anterior pituitary, a key endocrine organ in animals and humans. In this study, we separated and identified extracellular vesicles from the anterior pituitary of the Duroc swine model. Total RNA was extracted and RNA-seq was performed, followed by a comprehensive analysis of miRNAs, lncRNAs, and circRNAs. Resultantly, we obtained 416 miRNAs, 16,232 lncRNAs, and 495 circRNAs. Furthermore, GO and KEGG enrichment analysis showed that the ncRNAs in extracellular vesicles may participate in regulating intracellular signal transduction, cellular component organization or biogenesis, small molecule binding, and transferase activity. The cross-talk between them also suggested that they may play an important role in the signaling process and biological regulation. This is the first report of ncRNA data in the anterior pituitary extracellular vesicles from the duroc swine breed, which is a fundamental resource for exploring detailed functions of extracellular vesicles from the anterior pituitary.

Role of MicroRNAs and Long Non-Coding RNAs in Regulating Angiogenesis in Human Breast Cancer- A Molecular Medicine Perspective

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are proficient in regulating gene expression post-transcriptionally. Considering the recent trend in exploiting non-coding RNAs (ncRNAs) as cancer therapeutics, the potential use of miRNAs and lncRNAs as biomarkers and novel therapeutic agents against angiogenesis is an important scientific aspect. An estimated 70% of the genome is actively transcribed, only 2% of which codes for known protein-coding genes. Long noncoding RNAs (lncRNAs) are a large and diverse class of RNAs > 200 nucleotides in length, and not translated into protein, and are of utmost importance and it governs the expression of genes in a temporal, spatial, and cell context-dependent manner. Angiogenesis is an essential process for organ morphogenesis and growth during development, and it is relevant during the repair of wounded tissue in adults. It is coordinated by an equilibrium of pro-and anti-angiogenic factors; nevertheless, when affected, it promotes several diseases, including breast cancer. Signaling pathways involved here are tightly controlled systems that regulate the appropriate timing of gene expression required for the differentiation of cells down a particular lineage essential for proper tissue development. Lately, scientific reports are indicating that ncRNAs, such as miRNAs, and lncRNAs, play critical roles in angiogenesis related to breast cancer. The specific roles of various miRNAs and lncRNAs in regulating angiogenesis in breast cancer, with particular focus on the downstream targets and signaling pathways regulated by these ncRNAs with molecular medicine perspective, are highlighted in this write-up.

Noncoding RNAs: biology and applications-a Keystone Symposia report

The human transcriptome contains many types of noncoding RNAs, which rival the number of protein-coding species. From long noncoding RNAs (lncRNAs) that are over 200 nucleotides long to piwi-interacting RNAs (piRNAs) of only 20 nucleotides, noncoding RNAs play important roles in regulating transcription, epigenetic modifications, translation, and cell signaling. Roles for noncoding RNAs in disease mechanisms are also being uncovered, and several species have been identified as potential drug targets. On May 11-14, 2021, the Keystone eSymposium "Noncoding RNAs: Biology and Applications" brought together researchers working in RNA biology, structure, and technologies to accelerate both the understanding of RNA basic biology and the translation of those findings into clinical applications.

Evolving Landscape of Long Non-coding RNAs in Cerebrospinal Fluid: A Key Role From Diagnosis to Therapy in Brain Tumors

Long non-coding RNAs (lncRNAs) are a type of non-coding RNAs that act as molecular fingerprints and modulators of many pathophysiological processes, particularly in cancer. Specifically, lncRNAs can be involved in the pathogenesis and progression of brain tumors, affecting stemness/differentiation, replication, invasion, survival, DNA damage response, and chromatin dynamics. Furthermore, the aberrations in the expressions of these transcripts can promote treatment resistance, leading to tumor recurrence. The development of next-generation sequencing technologies and the creation of lncRNA-specific microarrays have boosted the study of lncRNA etiology. Cerebrospinal fluid (CSF) directly mirrors the biological fluid of biochemical processes in the brain. It can be enriched for small molecules, peptides, or proteins released by the neurons of the central nervous system (CNS) or immune cells. Therefore, strategies that identify and target CSF lncRNAs may be attractive as early diagnostic and therapeutic options. In this review, we have reviewed the studies on CSF lncRNAs in the context of brain tumor pathogenesis and progression and discuss their potential as biomarkers and therapeutic targets.

The role of long noncoding RNAs in patients with Luminal A invasive breast ductal carcinoma

Breast cancer is the most common form of cancer in women around the world. The molecular mechanisms of this heterogeneous disease have been extensively investigated; but yet; It requires a lot of sensitive and specific markers for prognosis and early detection approaches. Non-protein coding RNAs known as lncRNAs have been reported in tumorigenic involvement so they can be used for therapeutic purposes. In the present study, the expression levels of CCAT1, PDCD4, PDCD4-AS1, and MEG3 LncRNA in adjacent tumor and breast tissue in 88 Iranian patients were evaluated by quantitative real-time PCR. CCAT1 was significantly expressed and PDCD4-AS1 decreased in tumor samples, PDCD4 and PDCD4-AS1 showed a positive correlation with each other, higher levels of PDCD4-AS1 were associated with better survival, tumor samples showed lower levels of PDCD4 in Showed comparisons with normal tissue. Our findings suggest that lncRNAs play an important role in controlling gene expression after transcription of major tumor suppressors or carcinogenic genes, leading to the development of triple-negative breast cancer (TNBC). In conclusion, this study investigated the prognostic role of lncRNA in breast cancer patients.

The Long Non-coding RNA Cytoskeleton Regulator (CYTOR) Sponges microRNA- 206 (miR-206) to Promote Proliferation and Invasion of HP75 Cells

BACKGROUND

The role and mechanism of long non-coding RNA cytoskeleton regulator (CYTOR) in Invasive Pituitary Adenomas (IPA) have not been elucidated previously.

OBJECTIVE

This study aimed to investigate the interaction between CYTOR and miR-206 and their roles in IPA using HP75 cells as the model.

METHODS

The expression levels of CYTOR and miR-206 were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in IPA tissues and cell lines. The Chi-square test was used to analyze the correlation between CYTOR expression and clinical-pathological parameters. HP75 cell proliferation was detected by Cell Counting Kit-8 assay and colony formation assay. Scratch healing experiments and Transwell assay were used to detect migration and invasion of HP75 cells. The relationship between CYTOR and miR-206 was predicted by bioinformatics and verified by qRT-PCR and the dual-luciferase reporter gene method.

RESULTS

CYTOR is up-regulated in IPA tissues and cell lines. The high expression of CYTOR is associated with adenoma invasiveness and adenoma size of the patients. Down-regulation of CYTOR decreases the proliferation, migration and invasion of HP75 cells, while up-regulation of miR-206 can inhibit proliferation, migration and invasion of HP75 cells. MiR-206 is identified as a target of CYTOR and could be negatively regulated by it in IPA.

DISCUSSION

CYTOR, as a tumor-promoting factor, facilitates the proliferation, migration and invasion of HP75 cells through sponging miR-206.

CONCLUSION

The CYTOR-miR-206 axis provides new insights into the diagnosis and treatment of IPA.

Novel Insights into Pituitary Tumorigenesis: Genetic and Epigenetic Mechanisms

Substantial advances have been made recently in the pathobiology of pituitary tumors. Similar to many other endocrine tumors, over the last few years we have recognized the role of germline and somatic mutations in a number of syndromic or nonsyndromic conditions with pituitary tumor predisposition. These include the identification of novel germline variants in patients with familial or simplex pituitary tumors and establishment of novel somatic variants identified through next generation sequencing. Advanced techniques have allowed the exploration of epigenetic mechanisms mediated through DNA methylation, histone modifications and noncoding RNAs, such as microRNA, long noncoding RNAs and circular RNAs. These mechanisms can influence tumor formation, growth, and invasion. While genetic and epigenetic mechanisms often disrupt similar pathways, such as cell cycle regulation, in pituitary tumors there is little overlap between genes altered by germline, somatic, and epigenetic mechanisms. The interplay between these complex mechanisms driving tumorigenesis are best studied in the emerging multiomics studies. Here, we summarize insights from the recent developments in the regulation of pituitary tumorigenesis.

Altered Long Noncoding RNA Expression Profile in Multiple Myeloma Patients with Bisphosphonate-Induced Osteonecrosis of the Jaw

Bisphosphonates (BPs) are inhibitors of osteoclast-mediated bone resorption used for the treatment of multiple myeloma (MM) patients with osteolytic lesions. Bisphosphonate-induced osteonecrosis of the jaw (BONJ) is an infrequent drug-caused adverse event of these agents. Long noncoding RNAs (lncRNAs) are a set of more than 200 base pairs, noncoding RNA molecules, which are critical posttranscriptional regulators of gene expression. Our study was aimed at evaluating 17 lncRNAs, whose targets were previously validated as key elements in MM, bone metabolism, and angiogenesis in MM subjects without BONJ (MM group), in MM subjects with BONJ (BONJ group), and a group of healthy controls (CTRL group). Our results demonstrated a different lncRNA profile in BONJ patients compared to MM patients and controls. Two lncRNAs (DANCR and MALAT1) were both downregulated compared to controls and MM, twelve (HOTAIR, MEG3, TP73-AS1, HOTTIP, HIF1A-AS2, MANTIS, CTD-2201E18, CTD1-2003C8, R-471B22, RP1-43E13, RP11-553L6.5, and RP1-286D6) were overexpressed in MM with BONJ, and one (H19) was upregulated compared with only MM. Two lncRNAs (JHDMD1 and MTMR9LP) had higher expression, but these differences were not statistically significant. The examined lncRNAs target several genes and metabolic pathways. An altered lncRNA signature could contribute to the onset of BONJ or have a protective action. Targeting these lncRNAs could offer a possibility for the prevention or therapy of BONJ.

Long noncoding RNA PITPNA-AS1 promotes cervical cancer progression through regulating the cell cycle and apoptosis by targeting the miR-876-5p/c-MET axis

Cervical cancer is a common tumor type and a leading cause of tumor death among female in the world. However, the molecular mechanisms revealing the cervical cancer progression have not been fully investigated. Long noncoding RNA (LncRNA) PITPNA-AS1 is a newly found lncRNA, showing the promoting role in tumor growth. But its effects on cervical cancer development still remain unknown. In the study, we found that PITPNA-AS1 was markedly increased in human cervical cancer tissues and cell lines. PITPNA-AS1 over-expression elevated the proliferation of cervical cancer cells, whereas PITPNA-AS1 knockdown reduced the cell proliferation. Moreover, PITPNA-AS1 knockdown markedly accelerated the G0/G1 and reduced the G2/M phase transitions through decreasing the cyclin-dependent kinase (CDK)-2/4/6 and CyclinD1 expression levels. In addition, apoptosis was significantly induced by PITPNA-AS1 knockdown in cervical cancer cells. Importantly, PITPNA-AS1 was identified as the sponge of miR-876-5p, and a negative correlation was detected between PITPNA-AS1 and miR-876-5p in cervical cancer samples. Moreover, tyrosine-protein kinase MET (c-MET) was identified to be a down-streaming target gene of miR-876-5p in cervical cancer cells. PITPNA-AS1 meditated the effects of c-MET on the proliferation, apoptosis and cell cycle in cervical cancer cells by adsorbing miR-876-5p. In summary, targeting the PITPNA-AS1-associated signaling could be a therapeutic strategy for the treatment of cervical cancer.

Long non-coding RNA MEG3 is involved in osteogenic differentiation and bone diseases (Review)

Osteogenic differentiation originating from mesenchymal stem cells (MSCs) requires tight co-ordination of transcriptional factors, signaling pathways and biomechanical cues. Dysregulation of such reciprocal networks may influence the proliferation and apoptosis of MSCs and osteoblasts, thereby impairing bone metabolism and homeostasis. An increasing number of studies have shown that long non-coding (lnc)RNAs are involved in osteogenic differentiation and thus serve an important role in the initiation, development, and progression of bone diseases such as tumors, osteoarthritis and osteoporosis. It has been reported that the lncRNA, maternally expressed gene 3 (MEG3), regulates osteogenic differentiation of multiple MSCs and also acts as a critical mediator in the development of bone formation and associated diseases. In the present review, the proposed mechanisms underlying the roles of MEG3 in osteogenic differentiation and its potential effects on bone diseases are discussed. These discussions may help elucidate the roles of MEG3 in osteogenic differentiation and highlight potential biomarkers and therapeutic targets for the treatment of bone diseases.

Comprehensive circular RNA profiling reveals that hsa_circ_0001368 is involved in growth hormone-secreting pituitary adenoma development

Growth hormone-secreting pituitary adenoma (GHPA) represents about 20% of all histological subtypes of pituitary adenoma (PA), which may result in serious complications and shortened lifespan via growth-hormone (GH) hypersecretion. To date, no biomarkers of early diagnosis or therapeutic targets for GHPA treatment have yet been found. Recently, growing evidence has indicated that circular RNAs (circRNAs) are critical for the development and progression of numerous diseases, including cancers; however, their role in the pathogenesis of GHPA has not been reported. Here, we revealed the expression profile of circRNAs in GHPA using a circRNA microarray, and found 1938 circRNAs were upregulated and 1601 circRNAs were downregulated in GHPA versus normal control. Then the ten most up-regulated circRNAs were selected for the mapping of a circRNA-miRNA-target gene interaction network. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses further indicate that target genes were mostly enriched in the mTOR and the Wnt signaling pathway. Among these differentially expressed circRNAs, hsa_circ_0001368 was verified significant up-regulated by qRT-PCR, which was specific up-regulated in GHPA and correlated with the invasiveness and serum GH level of GHPA; functional studies indicated that knockdown of hsa_circ_0001368 significantly inhibited the proliferation, invasion and GH secreting level of GHPA primary culture cells. Moreover, hsa_circ_0001368 had a significant positive correlation with the pituitary-specific transcription factor Pit-1. In conclusion, our study identified a wealth of candidate circRNAs involved in GHPA and proposed that hsa_circ_0001368 may represent a novel potential biomarker and therapeutic target of GHPA.

HAND2-AS1 Inhibits Gastric Adenocarcinoma Cells Proliferation and Aerobic Glycolysis via miRNAs Sponge

Objective

To study the effect of lncRNA HAND2-AS1 on gastric adenocarcinoma (GA) cell property and explore its specific mechanism.

Methods

Data on stomach adenocarcinoma (STAD) were analyzed to screen differentially expressed lncRNA HAND2-AS1. RNA22-HAS database and dual luciferase reporter assay were applied to confirm the target relationship between HAND2-AS1/HIF3A and miR-184. The HAND2-AS1 and miR-184 expressions in tissue or cells were determined by qRT-PCR and Western blot. Besides, after GA cells (AGS) cultured in normoxic and hypoxic condition, phosphoenolpyruvate (PEP) and lactic acid were quantified by Phosphoenolpyruvate Fluorometric Assay Kit and Lactic Acid Detection kit, respectively. Additionally, colony formation assay, transwell invasion and migration assays were used to evaluate the abilities of cell invasion, migration, and proliferation in distinct conditions.

Results

The HAND2-AS1 and HIF3A expressions were down-regulated and miR-184 expression was up-regulated in GA tissues and cells. Dual luciferase reporter assay confirmed HAND2-AS1 and HIF3A were targeted by miR-184. AGS cell proliferation abilities were restrained by HAND2-AS1 and HIF3A overexpression and enhanced by miR-184, as well as migration and invasion abilities. In addition, HAND2-AS1 rescued enhanced AGS cell proliferation, cell migration, cell invasion abilities and glycolytic process caused by hypoxia via miR-184/HIF3A.

Conclusion

LncRNA HAND2-AS1 could inhibit GA cell proliferation, migration and invasion abilities and glycolytic process induced by hypoxia through miR-184/HIF3A signaling.

Genome-Wide Analysis and Function Prediction of Long Noncoding RNAs in Sheep Pituitary Gland Associated with Sexual Maturation

Long noncoding RNA (lncRNA) plays a crucial role in the hypothalamic-pituitary-testis (HPT) axis associated with sheep reproduction. The pituitary plays a connecting role in the HPT axis. However, little is known of their expression pattern and potential roles in the pituitary gland. To explore the potential lncRNAs that regulate the male sheep pituitary development and sexual maturation, we constructed immature and mature sheep pituitary cDNA libraries (three-month-old, TM, and nine-month-old, NM, respectively, n = 3) for lncRNA and mRNA high-throughput sequencing. Firstly, the expression of lncRNA and mRNA were comparatively analyzed. 2417 known lncRNAs and 1256 new lncRNAs were identified. Then, 193 differentially expressed (DE) lncRNAs and 1407 DE mRNAs were found in the pituitary between the two groups. Moreover, mRNA-lncRNA interaction network was constructed according to the target gene prediction of lncRNA and functional enrichment analysis. Five candidate lncRNAs and their targeted genes HSD17B12, DCBLD2, PDPK1, GPX3 and DLL1 that enriched in growth and reproduction related pathways were further filtered. Lastly, the interaction of candidate lncRNA TCONS_00066406 and its targeted gene HSD17B12 were validated in in vitro of sheep pituitary cells. Our study provided a systematic presentation of lncRNAs and mRNAs in male sheep pituitary, which revealed the potential role of lncRNA in male reproduction.

LncRNA MEG3 inhibits HMEC-1 cells growth, migration and tube formation via sponging miR-147

Long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) has been identified as a regulatory molecule in angiogenesis. The goal of this study was to illustrate how MEG3 affects the angiogenesis of vascular endothelial cells. Expression of MEG3, miR-147 and intracellular cell adhesion molecule-1 (ICAM-1) in human microvascular endothelial cell line (HMEC-1) was altered by transfection, then cell viability, apoptosis, migration, tube formation, as well as the correlation among MEG3, miR-147 and ICAM-1 were explored. MEG3 was down-regulated during tube formation of HMEC-1 cells. MEG3 expression suppressed cells viability, migration and tube formation, while it induced apoptosis. MEG3 could bind with miR-147 and repress miR-147 expression. MiR-147 induced ICAM-1 expression, and contained ICAM-1 target sequences. The anti-atherogenic actions of MEG3 were inhibited by miR-147, and the anti-atherogenic actions of miR-147 suppression were also inhibited when ICAM-1 was overexpressed. Further, ICAM-1 overexpression showed activated roles in Wnt/β-catenin and Jak/Stat signaling pathways. In low-density lipoprotein receptor (Ldlr)−/− mice, MEG3 overexpression reduced CD68+, CD3+ and ICAM-1 areas in lesions and increased collagen content. MEG3 inhibited HMEC-1 cell growth, migration and tube formation. The anti-atherogenic actions of MEG3 might be mediated via sponging miR-147, and thereby repressing the expression of ICAM-1.

Construction of lncRNA regulatory networks reveal the key lncRNAs associated with Pituitary adenomas progression

Pituitary adenomas (PA) is one of the most frequent types of intracranial neoplasms. Long noncoding RNAs (lncRNAs) played important roles in the progression of human cancers, including PA. However, the roles of lncRNAs in PA remained to be further investigated. We performed analysis of GSE26966 dataset to identify differently expressed lncRNAs in PA. Co-expression network, lncRNA-RNA binding proteins network, and competing endogenous RNA networks were constructed. Moreover, we performed RT-qPCR assay to validate four key lncRNAs expression in PA. This study identified differently expressed mRNAs and lncRNAs by using GSE26966 database. Furthermore, we constructed lncRNA-mRNA co-expression, lncRNA-RBP interaction and ceRNA networks. Bioinformatics analysis showed these lncRNAs were involved in regulating mechanical stimulus, gene expression, JAK-STAT cascade, cell cycle arrest, FoxO signaling, HIF-1 signaling, Insulin signaling, Oxytocin signaling, and MAPK signaling. We also showed KCNQ1OT1, SNHG7, MEG3, and SNHG5 were down-regulated in PA. Our findings could provide a novel insight to understand the mechanisms of lncRNAs underlying PA pathogenesis and identify new biomarkers for PA.

MEG3/MIR-376B-3P/HMGA2 axis is involved in pituitary tumor invasiveness

OBJECTIVE

To date, long noncoding RNAs (lncRNAs) have proven to function as key regulators in tumorigenesis. Among these lncRNAs, MEG3 displays low levels in various neoplasms and tumor cell lines. However, the regulatory mechanism of MEG3 and MIR-376B-3P, one of the microRNAs from downstream gene clusters of the DLK1-MEG3 locus, remains insufficiently defined.

METHODS

The authors used quantitative real-time polymerase chain reaction analysis to analyze whether decreased MEG3 and MIR-376B-3P expression levels were associated with the invasiveness of clinical nonfunctioning pituitary adenomas (CNFPAs) in 30 patients. Furthermore, functional experiments unveiled the pathophysiological role of MEG3, MIR-376B-3P, and HMGA2 in pituitary-derived folliculostellate (PDFS) cell lines. Moreover, dual-luciferase reporter assay, Western blot analysis, and immunofluorescence were applied to reveal the correlations among MEG3, MIR-376B-3P, and HMGA2.

RESULTS

MEG3 and MIR-376B-3P were decreased in patients with CNFPA, and their transcriptional levels were highly associated with invasive CNFPAs. Moreover, excessive expression of MEG3 and MIR-376B-3P inhibited tumorigenesis and promoted apoptosis in PDFS cells. Importantly, the authors found that MEG3 acted as an enhancer of MIR-376B-3P expression. Furthermore, as a target gene of MIR-376B-3P, HMGA2 served as an oncogene in pituitary adenoma and could be negatively regulated by MEG3 via enriching MIR-376B-3P.

CONCLUSIONS

This study offers a novel mechanism of an MEG3/MIR-376B-3P/HMGA2 regulatory network in CNFPAs, which may become a breakthrough for anticancer treatments.

The Role of Long Noncoding RNAs in the Biology of Pituitary Adenomas

Long noncoding RNAs (lncRNAs) are a large group of noncoding RNAs 200 nucleotides long. lncRNAs that function as regulatory factors have been identified for several complex cellular processes, such as cell death, growth, differentiation, apoptosis, epigenetic regulation, and so on. Many lncRNAs have altered expression and are likely to play a functional role in oncogenesis. The pituitary adenoma is the second most common intracranial tumor. Despite this situation, the molecular mechanism of pituitary adenoma formation has not yet been fully identified. This review summarizes recent progress in the study of lncRNAs on the pathogenesis of pituitary tumors. We cover the latest results associated with this role and highlight the therapeutic possibilities for pituitary adenomas.

Maternally expressed gene 3 (MEG3): A tumor suppressor long non coding RNA

Maternally expressed gene 3 (MEG3) is a long non-coding RNA (lncRNA) located on chromosome 14q32.3. Direct sequencing experiments have shown monoallelic expression of this lncRNA. Several studies have shown down-regulation of this lncRNA in human cancers. In some cases, hypermethylation of the promoter region has been suggested as the underlying mechanism. Functional studies have shown that this lncRNA controls expression of several tumor suppressor genes and oncogenes among them are p53, RB, MYC and TGF-β. Through regulation of Wnt-β-catenin pathway, it also affects epithelial-mesenchymal transition. In vitro studies have demonstrated contribution of MEG3 in defining response to chemotherapeutic agents such as paclitaxel, cisplatin and oxaliplatin. Certain polymorphisms within MEG3 are implicated in cancer risk (rs7158663, rs4081134 and rs11160608) or therapeutic response of cancer patients (rs10132552). Taken together, this lncRNA is regarded as a putative cancer biomarker and treatment target. In the current review, several aspects of the participation of MEG3 in carcinogenesis are discussed.

Structural characterization of maternally expressed gene 3 RNA reveals conserved motifs and potential sites of interaction with polycomb repressive complex 2

Long non-coding RNAs (lncRNAs) have emerged as key players in gene regulation. However, our incomplete understanding of the structure of lncRNAs has hindered molecular characterization of their function. Maternally expressed gene 3 (Meg3) lncRNA is a tumor suppressor that is downregulated in various types of cancer. Mechanistic studies have reported a role for Meg3 in epigenetic regulation by interacting with chromatin-modifying complexes such as the polycomb repressive complex 2 (PRC2), guiding them to genomic sites via DNA-RNA triplex formation. Resolving the structure of Meg3 RNA and characterizing its interactions with cellular binding partners will deepen our understanding of tumorigenesis and provide a framework for RNA-based anti-cancer therapies. Herein, we characterize the architectural landscape of Meg3 RNA and its interactions with PRC2 from a functional standpoint.

FOXP1-induced lncRNA CLRN1-AS1 acts as a tumor suppressor in pituitary prolactinoma by repressing the autophagy via inactivating Wnt/β-catenin signaling pathway

As the commonest type of functional pituitary tumor, prolactinoma takes up around 40-60% of functional pituitary tumors. Despite dedications attributed to the treatment of prolactinoma, complete cure remains difficult. Hence, it is of significance to bring to light the underlying mechanism of prolactinoma. Long noncoding RNAs (lncRNAs) are a group of transcripts which can regulate various biological processes. In the present study, we explored an lncRNA that was differentially downregulated in prolactinoma samples. LncRNA clarin 1 antisense RNA 1 (CLRN1-AS1) was downregulated in 42 patient samples and inactivated the Wnt/β-catenin signaling pathway. Functionally, CLRN1-AS1 suppressed cell proliferation, promoted apoptosis, and inhibited autophagy. Subcellular fractionation assay revealed that CLRN1-AS1 was located in the cytoplasm of prolactinoma cells. Based on bioinformatics analysis and mechanism experiments, we determined that CLRN1-AS1 acted as a competing endogenous RNA (ceRNA) by sponging miR-217 to upregulate the dickkopf WNT signaling pathway inhibitor 1 (DKK1). Furthermore, Forkhead box P1 (FOXP1) was verified to be a transcription suppressor of CLRN1-AS1. In summary, this study revealed that FOXP1-induced CLRN1-AS1 regulated cellular functions in pituitary prolactinoma by sponging miR-217 to release the DKK1/Wnt/β-catenin signaling pathway.

Long non-coding RNA 00607 as a tumor suppressor by modulating NF-κB p65/p53 signaling axis in hepatocellular carcinoma

Accumulating evidence suggests that long non-coding RNA (lncRNA) plays important roles in some malignant tumors. However, the mechanism underlying how lncRNA regulates hepatocellular carcinoma (HCC) process remains largely unknown. In this study, we explored the potential role of lncRNA 00607 as a novel tumor suppressor in HCC. In this study, we examined the regulation of lncRNA 00607 by the important inflammatory cytokine tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We also determined the expression of LINC000607 in 159 HCC tumors and paired adjacent tissues. Effects of LINC000607 in HCC proliferation and apoptosis were examined in vitro in HCC cell lines and in vivo tumor xenografts. Furthermore, we also examine underlying mechanism by which lncRNA 00607 regulates NF-κB p65 and how LIN00607 exerts its tumor suppressor role in HCC. We found that lncRNA 00607 expression level is lower in HCC tumors compared with matched normal liver tissue, and its low expression predicts worse prognosis in HCC. Functionally, lncRNA 00607 overexpression leads to decreased HCC cell proliferation in vitro and in vivo, enhanced apoptosis and chemotherapeutic drug sensitivity. Mechanistically, lncRNA 00607 inhibits the p65 transcription by binding to the p65 promoter region, therefore contributing to increased p53 levels in HCC. Taken together, the findings of this study show that the TNF-α/IL-6-lncRNA 00607-NF-κB p65/p53 signaling axis represents a novel therapeutic avenue in cancer chemotherapy.

circOMA1-Mediated miR-145-5p Suppresses Tumor Growth of Nonfunctioning Pituitary Adenomas by Targeting TPT1

CONTEXT

Nonfunctioning pituitary adenomas (NFPAs) are the major cause of hypopituitarism and infertility. However, the pathogenesis of NFPAs remains largely unknown. Previous studies have demonstrated the crucial role of miRNAs in the progression of pituitary adenomas. Increasing evidence has indicated that circular RNAs (circRNAs) might mediate miRNA transcriptional activity, providing new insights to study the pathogenesis of NFPAs.

OBJECTIVES

To explore the regulation and activity of the circRNA-miRNA-mRNA axis in the tumorigenesis of NFPAs.

DESIGN

The function of miR-145-5p in NFPAs was investigated invitro and invivo. The mechanical details were explored and potential targets of miR-145-5p were identified. Finally, miR-145-5p-associated circRNAs were functionally recognized and confirmed.

RESULTS

miR-145-5p was markedly decreased in NFPA samples and correlated negatively with NFPA invasiveness. Overexpression of miR-145-5p suppressed NFPA cell proliferation and invasiveness and promoted apoptosis. Further results confirmed that translationally controlled tumor protein (TPT1) is a target of miR-145-5p and mediated the effect of miR-145-5p. TPT1 and its downstream factors Mcl-1 and Bcl-xL were downregulated, and Bax was upregulated by miR-145-5p. Moreover, circOMA1 (hsa_circRNA_0002316) was demonstrated to sponge miR-145-5p, whose suppression on NFPA cells was abrogated by circOMA1 overexpression. circOMA1 silencing exhibited a similar inhibitory effect with miR-145-5p overexpression by downregulating TPT1. We found that circOMA1 could further upregulate Mcl-1 and Bcl-xL and downregulate Bax.

CONCLUSIONS

circOMA1 promotes NFPA progression by acting as the sponge of tumor suppressor miR-145-5p to regulate the TPT1 signaling pathway, revealing a therapeutic target in preventing the tumorigenesis of NFPAs.

MEG3 is associated with gsp oncogene regulation of growth hormone hypersecretion, proliferation and invasiveness of human GH-secreting adenomas

Overactivation of the Gs-mediated pathway by mutations of the G-protein α subunit (Gsα), a gsp oncogene, results in increased growth hormone (GH) hypersecretion and reduced tumor volume in patients with GH-secreting pituitary tumors. However, the mechanism underlying the clinical characteristics of gsp oncogene requires further investigation. Cyclic adenosine monophosphate-responsive element binding (CREB), as a downstream target gene of gsp oncogene, is implicated in activating maternally expressed gene 3 (MEG3). The present study proposes that gsp oncogene mediates MEG3-regulating GH hypersecretion, resulting in the small tumor size of GH-secreting tumors. Therefore, the present study detected Gsα mutations by polymerase chain reaction in GH-secreting tumors, and revealed that Gsα mutations were observed in 7/25 (28%) GH-secreting tumors. Gsp-positive tumors indicated significantly increased levels of phosphorylated p-CREB (P<0.0001) and MEG3 (P=0.039), compared with gsp-negative tumors. The results indicated that MEG3 levels were positively correlated with GH and IGF-1 levels, and negatively correlated with the tumor volume of GH-secreting tumors. The group with gsp-positive or with high MEG3 expression indicated a significantly reduced proportion of invasiveness and lower Ki-67 index, compared with the gsp-negative or low MEG3 expression group. In conclusion, gsp oncogene may mediate MEG3 by promoting GH hypersecretion, resulting in smaller tumors, as well as suppressing proliferation and invasiveness of GH-secreting pituitary tumors.

Long Non-coding RNAs Contribute to the Inhibition of Proliferation and EMT by Pterostilbene in Human Breast Cancer

Background: There is increasing evidence that long non-coding RNAs (lncRNAs) are involved in the process of carcinogenesis and treatment using chemotherapy. Pterostilbene, a phytochemical agent with natural antioxidant and anti-inflammatory properties, has been shown to modulate oncogenic processes in many cancers. However, there has been limited research on the association between pterostilbene and the expression of lncRNAs.

Methods: MCF7 breast cancer cells were treated with various concentrations of pterostilbene and their gene expression profile was analyzed by quantitative real-time PCR, Western blotting and immunofluorescence.

Results: Treatment with pterostilbene inhibited cell proliferation and epithelial-to-mesenchymal transition (EMT), and increased cell apoptosis, autophagy and ER stress. The Akt/mTOR pathway was downregulated, but p38 MAPK/Erk signaling was activated in cells following treatment with pterostilbene. Pterostilbene increased the expression of the lncRNAs MEG3, TUG1, H19, and DICER1-AS1 whereas the expression of LINC01121, PTTG3P, and HOTAIR declined. Knockdown of lncRNA H19 resulted in a reduction of the cell invasion, with the cells becoming more sensitive to pterostilbene therapy.

Conclusions: These results suggest that efficient optimum disruption of lncRNA expression might possibly improve the anti-tumor effects of phytochemical agents, thus serving as a potential therapy for breast cancer.

Restoration of miRNA-148a in pancreatic cancer reduces invasion and metastasis by inhibiting the Wnt/β-catenin signaling pathway via downregulating maternally expressed gene-3

Various microRNAs (miRNA) have been recognized potential novel tumor markers and have a critical role in cancer development and progression. Recently, methylation of miRNA-148a was identified as a crucial biochemical process in the progression of cancer. However, its potential role and in pancreatic cancer as well as the underlying mechanisms have remained largely elusive. The present study investigated the potential antitumor effect of miR-148a as well as its impact on invasion and metastasis in pancreatic cancer. It was found that the expression of miRNA-148a and the potential predictive biomarker maternally expressed gene-3 (MEG-3) were obviously decreased in human pancreatic cancer tissues compared with those in adjacent non-tumorous tissues. Furthermore, miR-148a was found to be downregulated in pancreatic cancer cell lines compared with normal pancreatic cells through promoter methylation. An MTT assay and a clonogenic assay demonstrated that restoration of miRNA-148a inhibited the proliferation and colony formation of pancreatic cancer cells. In addition, miR-148a transduction led to the upregulation of MEG-3 expression and promoted apoptosis of pancreatic cancer cells. Western blot analysis revealed that transduction of miR-148a markedly decreased the expression levels of C-myc, cyclin D1 and β-catenin in pancreatic cancer cells. Methylation of miR-148a not only decreased the endogenous β-catenin levels but also inhibited the nuclear translocation of β-catenin to delay cell cycle progression. Furthermore, ectopic miR-148a methylation inhibited pancreatic cancer cell migration and invasion via causing an upregulation of MEG-3 expression. Most importantly, ectopic overexpression of miR-148a in pancreatic cancer cells inhibited tumor formation in an animal experiment. Taken together, miR-148a methylation is a crucial regulatory process to inhibit the proliferation and invasion of pancreatic cancer cells, and transduction of miR-148a suppressed the proliferation of pancreatic cancer cells through negative regulation of the Wnt/β-catenin signaling pathway. The findings of the present study suggested that miRNA-148a acts as a tumor suppressor in pancreatic cancer and may contribute to the development of novel treatments for pancreatic cancer.

Mouse models in endocrine tumors

Endocrine and neuroendocrine tumors comprise a highly heterogeneous group of neoplasms that can arise from (neuro)endocrine cells, either from endocrine glands or from the widespread diffuse neuroendocrine system, and, consequently, are widely distributed throughout the body. Due to their diversity, heterogeneity and limited incidence, studying in detail the molecular and genetic alterations that underlie their development and progression is still a highly elusive task. This, in turn, hinders the discovery of novel therapeutic options for these tumors. To circumvent these limitations, numerous mouse models of endocrine and neuroendocrine tumors have been developed, characterized and used in pre-clinical, co-clinical (implemented in mouse models and patients simultaneously) and post-clinical studies, for they represent powerful and necessary tools in basic and translational tumor biology research. Indeed, different in vivo mouse models, including cell line-based xenografts (CDXs), patient-derived xenografts (PDXs) and genetically engineered mouse models (GEMs), have been used to delineate the development, progression and behavior of human tumors. Results gained with these in vivo models have facilitated the clinical application in patients of diverse breakthrough discoveries made in this field. Herein, we review the generation, characterization and translatability of the most prominent mouse models of endocrine and neuroendocrine tumors reported to date, as well as the most relevant clinical implications obtained for each endocrine and neuroendocrine tumor type.

Long noncoding RNAs: regulation, function and cancer

Long noncoding RNAs (lncRNAs) are non-protein-coding RNA transcripts that exert a key role in many cellular processes and have potential toward addressing disease etiology. Here, we review existing noncoding RNA classes and then describe a variety of mechanisms and functions by which lncRNAs regulate gene expression such as chromatin remodeling, genomic imprinting, gene transcription and post-transcriptional processing. We also examine several lncRNAs that contribute significantly to pathogenesis, oncogenesis, tumor suppression and cell cycle arrest of diverse cancer types and also give a summary of the pathways that lncRNAs might be involved in.

Long non-coding RNAs in thyroid cancer: Biological functions and clinical significance

Thyroid cancer is the most common endocrine malignant tumor with rapidly increasing incidence in recent decades. Although the majority of thyroid cancers are relatively indolent, some cases still have a risk of developing into more aggressive and lethal forms of thyroid cancers. Similar to other malignancies, thyroid tumorigenesis is a multistep process involving the accumulation of a large number of genetic and epigenetic alterations. Thus, determination of the mechanisms of tumorigenesis is an urgent need for thyroid cancer treatment. Long noncoding RNAs (LncRNAs) have recently been demonstrated to participate in cancer progression. However, their role and molecular mechanism in thyroid cancer remain largely unclear. In this review, we focus on the dysregulation of lncRNAs in thyroid cancer, summarize the latest findings regarding the functions and mechanism of lncRNAs in thyroid cancer, and discuss their potential clinical significance in diagnosis and prognosis of thyroid cancer.

Deciphering the roles of lncRNAs in breast development and disease

Breast cancer is the second leading cause of cancer related deaths in women. It is therefore important to understand the mechanisms underlying breast cancer development as well as raises the need for enhanced, non-invasive strategies for novel prognostic and diagnostic methods. The emergence of long non-coding RNAs (lncRNAs) as potential key players in neoplastic disease has received considerable attention over the past few years. This relatively new class of molecular regulators has been shown from ongoing research to act as critical players for key biological processes. Deregulated expression levels of lncRNAs have been observed in a number of cancers including breast cancer. Furthermore, lncRNAs have been linked to breast cancer initiation, progression, metastases and to limit sensitivity to certain targeted therapeutics. In this review we provide an update on the lncRNAs associated with breast cancer and mammary gland development and illustrate the versatility of such lncRNAs in gene control, differentiation and development both in normal physiological conditions and in diseased states. We also highlight the therapeutic and diagnostic potential of lncRNAs in cancer.

Long noncoding RNA MALAT1 knockdown reverses chemoresistance to temozolomide via promoting microRNA-101 in glioblastoma

Glioblastoma (GBM) is the most common and lethal tumor of the central nervous system with highly infiltrative and resistant to chemotherapy. Temozolomide (TMZ) is widely used as the first-line treatment for the therapy of GBM. However, a considerable percentage inherent or acquired resistance in GBM accounts for many treatment failures of the TMZ chemotherapy. Therefore, a deeper understanding of the molecular characteristics underlying TMZ resistance and the identification of novel therapeutic target is urgent. Here, we show that MALAT1 was significantly upregulated in TMZ-resistant GBM cells. On the other hand, MALAT1 knockdown reduces TMZ resistance of GBM cells both in vitro and in vivo by inhibiting cell proliferation and promoting apoptosis. We also show that miR-101 overexpression reduced TMZ resistance of GBM cells and played an antagonistic role compared with MALAT1. Importantly, we demonstrate that MALAT1 promoted the chemoresistance through suppressing miR-101 signaling pathway via directly binding it in GBM cells. In conclusion, our study indicates that knockdown of MALAT1 reverses chemoresistance to TMZ via promoting miR-101 regulatory network in GBM and thus offers a novel prognostic marker and potential target for GBM TMZ-based chemotherapy.

lncRNA PVT1 promotes the angiogenesis of vascular endothelial cell by targeting miR‑26b to activate CTGF/ANGPT2

Angiogenesis is essential for various biological processes, including tumor blood supply delivery, cancer cell growth, invasion and metastasis. Plasmacytoma variant translocation 1 (PVT1) long noncoding RNA (lncRNA) has been previously reported to affect angiogenesis of glioma microvascular endothelial cells by regulating microRNA (miR)‑186 expression level. However, the specific underlying molecular mechanism of PVT1 regulation of angiogenesis in vascular endothelial cells remains to be elucidated. The present study investigated the role of PVT1 in cell proliferation, migration and vascular tube formation of human umbilical vein endothelial cells (HUVECs) using MTT assay, Transwell migration assay and in vitro vascular tube formation assay, respectively. In order to determine the effect of miR‑26b on cell proliferation, migration and vascular tube formation of HUVECs, miR‑26 mimic or miR‑26b inhibitor were transfected into HUVECs. Reverse transcription‑quantitative polymerase chain reaction and western blotting were conducted to quantify the mRNA and protein expression levels of target genes. The present study confirmed that miR‑26b bound 3'‑untranslated region (3'‑UTR) and subsequently influenced gene expression level using dual luciferase reporter assay. The current study observed that PVT1 affected cell proliferation, migration and in vitro vascular tube formation of HUVECs. In addition, it was determined that PVT1 was able to bind and degrade miR‑26b to promote connective tissue growth factor (CTGF) and angiopoietin 2 (ANGPT2) expression. miR‑26b was also identified to have a suppressive role in cell proliferation, migration and in vitro vascular tube formation of HUVECs via binding 3'‑UTR regions and downregulating CTGF and ANGPT2 expression levels. The current findings may improve the understanding of the underlying mechanism of PVT1 contributing to angiogenesis of vascular endothelial cells and offer rationale for targeting PVT1 to treat angiogenesis dysfunction‑associated diseases, including cancer metastasis.

Genome-wide analysis of differentially expressed lncRNAs and mRNAs in primary gonadotrophin adenomas by RNA-seq

Recently, long non-coding RNAs (lncRNAs) have received increased research interest owing to their participation via distinct mechanisms in the biological processes of nonfunctional pituitary adenomas. However, changes in the expression of lncRNAs in gonadotrophin adenoma, which is the most common nonfunctional pituitary adenomas, have not yet been reported. In this study, we performed a genome-wide analysis of lncRNAs and mRNAs obtained from gonadotrophin adenoma patients’ samples and normal pituitary tissues using RNA-seq. The differentially expressed lncRNAs and mRNAs were identified using fold-change filtering. We identified 839 lncRNAs and 1015 mRNAs as differentially expressed. Gene Ontology analysis indicated that the biological functions of differentially expressed mRNAs were related to transcription regulator activity and basic metabolic processes. Ingenuity Pathway Analysis was performed to identify 64 canonical pathways that were significantly enriched in the tumor samples. Furthermore, to investigate the potential regulatory roles of the differentially expressed lncRNAs on the mRNAs, we constructed general co-expression networks for 100 coding and 577 non-coding genes that showed significantly correlated expression patterns in tumor cohort. In particular, we built a special sub-network of co-expression involving 186 lncRNAs interacting with 15 key coding genes of the mTOR pathway, which might promote the pathogenesis of gonadotrophin tumor. This is the first study to explore the patterns of genome-wide lncRNAs expression and co-expression with mRNAs, which might contribute to the molecular pathogenesis of gonadotrophin adenoma.

Identification of long non-coding RNAs in the immature and mature rat anterior pituitary

Many long non-coding RNAs (lncRNAs) have been identified in several types of human pituitary adenomas and normal anterior pituitary, some of which are involved in the pathogenesis of pituitary adenomas. However, a systematic analysis of lncRNAs expressed at different developmental stages of normal pituitary, particularly in rats, has not been performed. Therefore, we contrasted two cDNA libraries of immature (D15) and mature (D120) anterior pituitary in rat that were sequenced on an Illumina HiSeq Xten platform, and a total of 29,568,806,352 clean reads were identified. Notably, 7039 lncRNA transcripts corresponded to 4442 lncRNA genes, and 1181 lncRNA transcripts were significantly differentially expressed in D15 and D120. In addition, 6839 protein-coding genes (<100 kb upstream and downstream) were the nearest neighbors of 4074 lncRNA genes. An interaction network of lncRNAs and the follicle-stimulating hormone beta-subunit (FSHb) gene was constructed using the lncRNATargets platform, and three novel lncRNAs were obtained. Furthermore, we detected the expression of the novel lncRNAs and ten highly expressed lncRNAs that were randomly selected through quantitative PCR (qPCR). The rat anterior pituitary lncRNA content identified in this study provides a more in-depth understanding of the roles of these lncRNAs in hormone and reproduction development and regulation in mammals.

LncRNA MEG3 ameliorates respiratory syncytial virus infection by suppressing TLR4 signaling

Maternally expressed gene 3 (MEG3), a long noncoding RNA (lncRNA) has been dysregulated in various tumors. However, the expression level and functional role of MEG3 in the progression of respiratory syncytial virus (RSV) infection remains to be elucidated. The present study quantified the expression level of MEG3 in the nasopharyngeal (NPA) samples of RSV‑infected patients and in BEAS‑2B cells infected with RSV. The findings of the present study demonstrated that the expression level of lncRNA MEG3 was reduced in the NPA samples of RSV‑infected patients and in BEAS‑2B cells infected with RSV. In vitro transfection revealed increased mRNA expression levels of toll‑like receptor 4 (TLR4), tumor necrosis factor‑α (TNFα) and interleukin (IL)‑8 following RSV infection in BEAS‑2B cells. Additionally, ectopic expression of MEG3 reduced the expression level of TLR4, subsequently suppressing the mRNA expression levels of TNFα and IL‑8, indicating the protective role of MEG3 in the process of RSV infection. It is of note, that RSV infection‑induced p38 mitogen activated protein kinase (MAPK) and nuclear factor‑κB (NF‑κB) activation was partly abolished by overexpression of MEG3. In conclusion, to the best of our knowledge, the present study provided the first evidence that lncRNA MEG3 expression level was reduced in the NPA samples of patients with RSV infection and RSV‑infected cells. Additionally, it was demonstrated that MEG3 protected human airway epithelial cells from RSV infection, primarily by suppressing TLR4‑dependent p38 MAPK and NF‑κB signaling.

Long noncoding RNA MEG3, a potential novel biomarker to predict the clinical outcome of cancer patients: a meta-analysis

Numerous studies have demonstrated that the expression level of maternally expressed gene 3 (MEG3) was lost in various cancers. Low expression of MEG3 is associated with an increased risk of metastasis and a poor prognosis in cancer patients. This meta-analysis investigated the association between MEG3 levels and distant metastasis (DM), lymph node metastasis (LNM), overall survival (OS), and recurrence-free survival (RFS) of cancer patients. A total of 536 participants from 9 articles were finally enrolled. The results showed a significant negative association between MEG3 levels and DM (OR = 2.16, 95% CI = 0.99–4.71, P = 0.05, fixed-effect), and it could also predict poor OS (HR = 0.43, 95% CI = 0.15–1.24, P = 0.006, fixed-effect) and RFS (HR = 0.52, 95% CI = 0.29–0.92, P = 0.02, fixed-effect) in cancer patients. In conclusion, this meta-analysis indicated that MEG3 might serve as a potential novel biomarker for indicating the clinical outcomes in human cancers.

Down-regulation of long non-coding RNA MEG3 indicates an unfavorable prognosis in non-small cell lung cancer: Evidence from the GEO database

Long non-coding RNA (lncRNA) MEG3 (maternally expressed gene 3) is an imprinted gene that suppresses cells growth in various tumors. However, the association between MEG3 expression and prognosis in non-small cell lung cancer (NSCLC) has not been fully investigated. Seven datasets with 1144 patients were obtained from Gene Expression Omnibus (GEO) database (Affymetrix U133 Plus 2.0 platform). Association between MEG3 and other variables was tested using the chi-squared test. Kaplan-Meier survival analysis was carried out to explore the association between MEG3 expression and overall survival (OS)/progression free survival (PFS). Results of univariate and multivariate Cox regression analysis were represented in HR and 95%CI form. Summarized results and publication bias were showed by forest plots and funnel plots respectively. Differential expression of MEG3 was related to stage (GSE31210OS and GSE31210PFS), histology (GSE29013OS and GSE29013PFS) and gender (GSE29013PFS). In summary, low MEG3 expression was associated with shorter long-term survival time in several datasets (GSE3141 (p=0.039), GSE30219 (p=0.008) for OS and GSE30219 (p=0.048) for PFS). We found that MEG3 was an independent prognostic factor in GSE30219 for PFS (HR 0.666, 95%CI 0.458-0.969, p=0.033). The summarized results suggested that low MEG3 expression was a poor prognostic factor in NSCLC (HR=0.77, 95%CI 0.63-0.95). Specifically, the association between low MEG3 expression and poor prognosis was markedly significant in younger patients (≤60years old) (HR0.602, 95%CI 0.417-0.867, p=0.007). These findings indicate that MEG3 could be a novel prognostic factor for NSCLC patients.

Potential applications of MEG3 in cancer diagnosis and prognosis

LncRNAs are emerging as integral functional and regulatory components of normal biological activities and are now considered as critically involved in the development of different diseases including cancer. In this review, we summarized recent findings on maternally expressed gene 3 (MEG3), a noncoding lncRNA, locates in the imprinted DLK1–MEG3 locus on human chromosome 14q32.3 region. MEG3 is expressed in normal tissues but is either lost or decreased in many human tumors and tumor derived cell lines. Studies have demonstrated that MEG3 is associated with cancer initiation, progression, metastasis and chemo-resistance. MEG3 may affect the activities of TP53, MDM2, GDF15, RB1 and some other key cell cycle regulators. In addition, the level of MEG3 showed good correlation with cancer clinicopathological grade. In summary, MEGs is an RNA-based tumor suppressor and is involved in the etiology, progression, and chemosensitivity of cancers. The alteration of MEG3 levels in various cancers suggested the possibility of using MEG3 level for cancer diagnosis and prognosis.

Long non-coding RNA MEG3 inhibits cell growth of gliomas by targeting miR-93 and inactivating PI3K/AKT pathway

Gliomas are the most common cancers in the brain, accompanied with high morbility, occurrence, disability and mortality. Long non-coding RNAs (lncRNAs) have been proposed as promoter or inhibitor in many cancer processes. Previous findings have indicated that lncRNA-maternally expressed gene 3 (MEG3) is involved in tumorigenesis of several cancers, including glioma. However, the underlying mechanism of MEG3 in glioma remains elusive. In our study, MEG3 was found downregulated in glioma tissues compared with normal brain tissues. Downregulated expression of MEG3 was also detected in two human glioma cell lines (U-251, M059J) compared with normal astrocyte cells. MEG3 was then overexpressed by ligating to a lentiviral vector. Overexpressed MEG3 inhibited the proliferation of U-251 cells, and restrained the expression of proliferation marker proteins Ki67 and proliferating cell nuclear antigen (PCNA). However, cell apoptosis rate of U-251 cells and the expression of apoptosis marker proteins (caspase-3 and caspase-9) were elevated by MEG3. Furthermore, miR-93 was predicted a direct target of lncRNA-MEG3 by bioinformatics analysis. Overexpressed MEG3 counteracted the role of miR-93 in facilitating proliferation and inhibiting apoptosis in U-251 cells. Moreover, MEG3 restained the activation of phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT) pathway by reducing cytomembrane translocation of AKT. Finally, the in vivo experiment revealed that MEG3 strongly reduced tumor growth, tumor volume and the expression of Ki67 and PCNA. lncRNA-MEG3 also inhibited the level of miR-93 and the expression of PI3K/AKT pathway related proteins in vivo. Taken together, our research indicated a MEG3-miR-93-PI3K-AKT pathway in regulating the growth of glioma, providing a promising therapy for glioma.

LncRNA as a Therapeutic Target for Angiogenesis

BACKGROUND

Out of 3 billion base pairs in human genome only ~2% code for proteins; and out of 180,000 transcripts in human cells, about 20,000 code for protein, remaining 160,000 are non-coding transcripts. Most of these transcripts are more than 200 base pairs and constitute a group of long non-coding RNA (lncRNA). Many of the lncRNA have its own promoter, and are well conserved in mammals. Accumulating evidence indicates that lncRNAs act as molecular switches in cellular differentiation, movement, apoptosis, and in the reprogramming of cell states by altering gene expression patterns. However, the role of this important group of molecules in angiogenesis is not well understood. Angiogenesis is a complex process and depends on precise regulation of gene expression.

CONCLUSION

Dysregulation of transcription during this process may lead to several diseases including various cancers. As angiogenesis is an important process in cancer pathogenesis and treatment, lncRNA may be playing an important role in angiogenesis. In support of this, lncRNA microvascular invasion in hepatocellular carcinoma (MVIH) has been shown to activate angiogenesis. Furthermore, lncRNA-Meg3-knockout mouse showed increased expression of vascular endothelial growth factor pathway genes and increased cortical microvessel density. Overall, there is strong evidence that lncRNA is an important class of regulatory molecule, and a number of studies have demonstrated that these can be targeted to change cellular physiology and functions. In this review, we have attempted to summarize these studies and elucidate the potential of this novel regulatory molecule as a therapeutic target.

The inhibitory effect of MEG3/miR-214/AIFM2 axis on the growth of T-cell lymphoblastic lymphoma

T-cell lymphoblastic lymphoma (T-LBL) is an aggressive malignancy with poor prognosis and high recurrence rate. Long non-coding RNA (lncRNA)-MEG3 is an important tumor suppressor in various cancers. The present study investigated the potential role of maternally expressed gene 3 (MEG3) in the progression of T-LBL. Suppressed expression of MEG3 was detected in T-LBL tissues compared with adjacent histologically normal tissues. Down-regulated level of MEG3 was also found in three T-LBL cell lines (CCRF-CEM, Jurkat and SUP-T1) compared with human T-cell line H9. The proliferation of T-LBL cells was inhibited and cell apoptosis rate was largely promoted when MEG3 was upregulated by a lentiviral vector. Further research revealed that microRNA (miRNA)-214 is a direct target of MEG3. The expression of miR-214 was increased in T-LBL tissues and cell lines compared with control groups. Besides, decreased level of miR-214 was elevated adding miR-214 mimic in SUP-T1 cells transfected with LncRNA-MEG3. Similarly, upregulated level of miR-214 was downregulated adding miR-214 inhibitor in SUP-T1 cells transfected with MEG3 siRNA. Luciferase activity assay further confirmed the targeting relationship between MEG3 and miR-214. Moreover, AIFM2 protein was predicted as a target of miR-214. The expression of AIFM2 was increased by MEG3 and was downregulated by miR-214 mimic. miRNA-214 reversed the effect of MEG3 on inhibiting cell proliferation and inducing cell apoptosis and cell cycle arrest in SUP-T1 cells. Moreover, relative expression of AIFM2 had a positive correlation with the expression of MEG3 and was negatively affected by miR-214. In vivo, MEG3 effectively suppressed tumor growth and the expression of proliferation markers Ki-67 and proliferating cell nuclear antigen (PCNA). Taken together, our research revealed that MEG3 worked as an anti-oncogene in T-LBL, and the MEG3-miR-214-AIFM2 pathway regulated the growth of T-LBL, providing potential prognosis markers as well as new potential targets for T-LBL treatment.

Long non-coding RNA C5orf66-AS1 is downregulated in pituitary null cell adenomas and is associated with their invasiveness

Pituitary null cell adenoma is a challenging clinical condition, and its pathogenesis remains to be elucidated. We performed this study to determine the roles of C5orf66-AS1, NORAD, and TINCR in the pathogenesis and invasion of pituitary null cell adenomas. Expression of the three long non-coding RNAs in pituitary null cell adenoma tissues of 11 patients and normal pituitary tissues from four donors was examined by performing quantitative reverse transcription-polymerase chain reaction. We found that C5orf66-AS1 expression was lower in pituitary null cell adenoma tissues than in normal pituitary tissues. Moreover, C5orf66-AS1 expression level was significantly lower in invasive pituitary null cell adenomas than in non-invasive ones. After transfection of C5orf66-AS1 into pituitary adenoma cells, assessment of cell viability and invasion suggested that overexpressed C5orf66-AS1 inhibited cell viability and cell invasion. In silico algorithms predicted several cis- and trans-acting target genes of C5orf66-AS1, including PITX1 and SCGB3A1. In addition, expression of some of the predicted target genes was determined using microarray data of another cohort with pituitary null cell adenomas. It showed that some of these target genes were differentially expressed between pituitary null cell adenoma tissues and normal pituitary tissues as well as between invasive and non-invasive tumors. Co-expression analysis in RNA sequencing data showed that PAQR7 was the most correlated gene of C5orf66-AS1 and that several predicted trans-acting target genes, including SCGB3A1, were highly correlated with C5orf66-AS1. NORAD and TINCR expression was not statistically significant in the complete cohort; however, a negative correlation was observed between NORAD expression and maximum tumor diameter in some subgroups. These results indicate that C5orf66-AS1 suppresses the development and invasion of pituitary null cell adenomas. However, our results do not provide enough statistical evidence to support the roles of NORAD and TINCR in the development and invasion of pituitary null cell adenomas.

Dysfunction of the WT1-MEG3 signaling promotes AML leukemogenesis via p53-dependent and -independent pathways

Long non-coding RNAs (lncRNAs) play a pivotal role in tumorigenesis, exemplified by the recent finding that lncRNA maternally expressed gene 3 (MEG3) inhibits tumor growth in a p53-dependent manner. Acute myeloid leukemia (AML) is the most common malignant myeloid disorder in adults, and TP53 mutations or loss are frequently detected in patients with therapy-related AML or AML with complex karyotype. Here, we reveal that MEG3 is significantly downregulated in AML and suppresses leukemogenesis not only in a p53-dependent, but also a p53-independent manner. In addition, MEG3 is proven to be transcriptionally activated by Wilms’ tumor 1 (WT1), dysregulation of which by epigenetic silencing or mutations is causally involved in AML. Therefore MEG3 is identified as a novel target of the WT1 molecule. Ten–eleven translocation-2 (TET2) mutations frequently occur in AML and significantly promote leukemogenesis of this disorder. In our study, TET2, acting as a cofactor of WT1, increases MEG3 expression. Taken together, our work demonstrates that TET2 dysregulated WT1-MEG3 axis significantly promotes AML leukemogenesis, paving a new avenue for diagnosis and treatment of AML patients.

dNK derived IFN-γ mediates VSMC migration and apoptosis via the induction of LncRNA MEG3: A role in uterovascular transformation

INTRODUCTION

Appropriate spiral artery remodeling is critical for successful fetal development and pregnancy outcomes. The vascular smooth muscle cell (VSMC) loss and separation, involving cell apoptosis and migration, plays an important role in this process. Decidual natural killer cells (dNK)-derived interferon gamma (IFN-γ), a key regulator of uterine arterial remodeling, can facilitate separation of VSMC layers, however, the specific mechanisms of it action are unknown. Long non-coding RNA MEG3 functions as tumor suppressor by regulating apoptosis and migration. Moreover, IFN-γ has been shown to influence cell vitality through regulating MEG3 expression. However, the functional role of dNK derived IFN-γ and MEG3 on VSMC viability, as well as the relationship between IFN-γ and MEG3 in VSMCs, has not been completely elaborated.

METHODS

The up-regulation strategies and reagent treatment were employed to detect the effects of MEG3 and dNK/IFN-γ on VSMC proliferation, apoptosis and migration. At the same time, MEG3, p53 and matrix metalloproteinase 2 (MMP-2) expressions were investigated.

RESULTS

dNK/IFN-γ treatment led to up-regulation of MEG3 expression in VSMCs. Both MEG3 over-expression and dNK/IFN-γ treatment inhibited VSMC proliferation, stimulated VSMC migration and resulted in a small but significant induction of VSMC apoptosis, as well as promoted p53 and MMP-2 expression in VSMCs.

DISCUSSION

MEG3 is regulated by dNK-derived IFN-γ and regulates VSMC migration and apoptosis. Therefore, it may be an important positive regulator in VSMC loss from the maternal uterine spiral arteries during vascular transformation.

Upregulation of long noncoding RNA LOC100507661 promotes tumor aggressiveness in thyroid cancer

Recent advances in next-generation sequencing have revealed a variety of long noncoding RNAs (lncRNAs). However, studies of lncRNAs are at a very early stage, our knowledge of the biological functions and clinical implications remains limited. To investigate the roles of lncRNAs in thyroid cancers, we verified 56 lncRNAs identified as potential cancer-promoting genes in a previous study that analyzed 2394 tumor SNP arrays from 12 types of cancer. Based on verified sequence information in NCBI and Ensembl, we ultimately selected three candidate lncRNAs for detailed analysis. One of the candidates, LOC100507661, was strongly upregulated in thyroid cancer tissues relative to paired contralateral normal tissue. LOC100507661 was easily detectable in papillary and anaplastic thyroid cancer cell lines such as TPC1, BCPAP, C643, and 8505C, but not in the follicular thyroid cancer cell line FTC133. Stable overexpression of LOC100507661 promoted cell proliferation, migration, and invasion of thyroid cancer cells. Lymph node metastasis and BRAF V600E mutations were more frequent in papillary thyroid cancers with high LOC100507661 expression. Our data demonstrate that LOC100507661 expression is elevated in human thyroid cancer and may play a critical role in thyroid carcinogenesis.