MEG3 Expression Research Articles

Up-regulation of HOXA-AS2 and MEG3 long non-coding RNAs acts as a potential peripheral biomarker for bipolar disorder.

Bipolar disorder (BD) is a psychiatric condition that is frequently misdiagnosed and linked to inadequate treatment. Long non-coding RNAs (lncRNAs) have lately gained recognition as crucial genetic elements and are now regarded as regulatory mechanisms in the neurological system. Our objective was to measure the quantities of HOXA-AS2 and MEG3 ncRNA transcripts. HOXA-AS2 and MEG3 ncRNA levels were checked in the peripheral blood of 50 type I BD and 50 control samples by real-time PCR. Furthermore, we conducted ROC curve analysis and correlation analysis to examine the association between gene expression and specific clinical characteristics in instances with BD. Additionally, a computational study was performed to investigate the binding sites of miRNAs on the HOXA-AS2 and MEG3 lncRNAs. BD subjects showed a significant increase in the expression of HOXA-AS2 and MEG3 compared to controls. The lncRNAs HOXA-AS2 and MEG3 have an area under the ROC curve (AUC) values of 0.70 and 0.71, respectively. There was a significant correlation between the expression levels of ncRNAs HOXA-AS2 and MEG3 in the peripheral blood of patients with BD and occupation scores. The data presented indicate a potential correlation between the expression of HOXA-AS2 and MEG3 lncRNAs with an elevated risk of BD. Furthermore, these lncRNAs may be linked to several molecular pathways. Our findings indicate that the amounts of lncRNAs HOXA-AS2 and MEG3 in transcripts might be a promising potential biomarker for patients with BD.

LncRNA MEG3 promotes aortic valve calcification by inducing osteoblast differentiation via Wnt catenin signaling pathway

Abstract Background Calcific aortic valve stenosis (CAVS) is the most common valvular heart disease in elderly population. This study aimed to investigate the role of long non-coding RNAs (lncRNAs) in the development of CAVS. Methods ldlr-/-mice were feeding with western diet for 6 months to induce CAVS. RNA-seq analysis was performed to identify differentially expressed molecular signaling between aortic valves of CAVS mice and control mice. The degree of aortic stenosis was detected by ultrasound. Calcium salt deposits were detected by Haematoxylin and eosin (H&E) staining, Von Kossa staining and alizarin red S staining. PCR and western blotting were employed to detect osteogenic differentiation markers after various interventions. Results A mouse CAVS model was successfully established, as evidenced by increased thickness and calcium deposition in the aortic valve leaflets and increased transvalvular peak jet velocity. RNA-seq analysis showed that lncRNA MEG3 was significantly enriched in aortic valves of CAVS mice as compared to that of control mice. MEG3 expression in aortic valve, assessed by RNA in situ hybridization and PCR, was also significantly upregulated during the osteoblast differentiation of AVICs in vitro. Gain- and loss-of-function experiments indicate that MEG3 could indeed promote osteoblast differentiation of primary AVICs as evidenced by increased calcified nodule formation and expressions of osteoblast differentiation markers (Runx2 and osterix). Consistent with these in vitro data, MEG3 knockdown in vivo through tail injection of antisense oligonucleotide chain MEG3 (ASO-MEG3) at 6 weeks interval for 12 weeks significantly attenuated aortic valve calcification in CAVS mice. Subsequent KEGG analysis demonstrated that the Wnt/β-catenin signaling pathway was significantly enriched during the CAVS progression. Overexpression of MEG3 activated the Wnt/β-catenin signaling pathway and upregulated osteogenic protein expressions, while this upregulation could be significantly ameliorated by Dickkopf 1, a Wnt/β-catenin pathway inhibitor. Conclusion Present study demonstrates that LncRNA MEG3 could promote aortic valve calcification by inducing osteoblast differentiation via activating Wnt/β-catenin signaling pathway. Our results provide experimental evidence of targeting MEG3 and Wnt/β-catenin signaling pathway as potential promising therapeutic option for prevention and treatment of aortic valve calcification.

The expression of long non-coding RNAs TP53TG1, LINC00342, MALAT1, H19 and MEG3 in type 2 <i>Diabetes mellitus</i>

Type 2 diabetes is a complex and multifactorial metabolic disorder. The frequency of type 2 diabetes has dramatically increased worldwide. Long non-coding RNAs play a regulatory role in pathological processes of type 2 diabetes. The aim of the study was to analyze lncRNA TP53TG1, LINC00342, MALAT1, H19, MEG3 in patients with type 2 diabetes and metabolic parameters, as well as the risk of diabetic retinopathy. Participants included 51 patients with diabetes and 70 healthy individuals. The expression of TP53TG1 and LINC00342 genes was significantly decreased in the patients with diabetes compared to healthy individuals. MALAT1 gene expression was higher in diabetes patient. H19 gene was increased in the patients with diabetic retinopathy compare patients without retinopathy. TP53TG1, LINC00342 and MEG3 expression was decreased in the patients with diabetic retinopathy and MALAT1 expression was increased. H19 is positively correlated with triglyceride levels, TP53TG1 and LINC00342 are positively correlated with HbA1c levels and fasting glucose levels. MALAT1 is negatively correlated with HDL levels and positively correlated with LDL levels. A decrease in the expression level of TP53TG1 and LINC00342 and an increase in the level of MALAT1 in diabetes, as well as an association with glycemic control, indicate the role of the studied non-coding RNAs in the development of type 2 diabetes mellitus and retinopathy and can be considered as candidates for early diagnosis of type 2 diabetes.

Genetic variants of LncRNAs HOTTIP and MEG3 influence nasopharyngeal carcinoma susceptibility and clinicopathologic characteristics in the Southern Chinese population

ObjectiveRecent studies have indicated that HOTTIP and MEG3 are associated with the initiation and progression of various types of tumors, including nasopharyngeal carcinoma (NPC). This investigation aimed to elucidate the impact of HOTTIP and MEG3 polymorphisms on the susceptibility and clinicopathologic characteristics of NPC.MethodsThis research employed next-generation sequencing and multiplex PCR to assess the polymorphisms of HOTTIP rs1859168 and MEG3 rs7158663 in 200 NPC and 200 healthy individuals respectively. HOTTIP and MEG3 expression were assessed via qRT-PCR assessment. Furthermore, the genotypes and alleles frequency of rs1859168 and rs7158663 were compared between healthy and NPC individuals to elucidate their influence on NPC susceptibility and relation with clinicopathologic characteristics.ResultsIn comparison with the healthy cohort, the presence of HOTTIP rs1859168 CC genotype and the C allele were markedly linked with increased NPC incidence (p < 0.05). Furthermore, the MEG3 rs7158663 AA genotype and the A allele also indicated an increased risk of NPC (p < 0.05). The subgroup analysis of age, EBV infection, gender, nationality, smoking, and drinking status revealed no marked association between rs1859168 and rs7158663 genotypes and these potential confounding factors. Moreover, it was observed that rs1859168 CC and rs7158663 AA genotypes were related to local tumor invasion and lymph node metastasis. Additionally, HOTTIP indicated a marked elevation, while MEG3 substantially reduced in NPC samples than the normal nasopharyngeal biospecimens. Patients who carried CC or CA genotypes rather than the HOTTIP rs1859168 AA genotype, had substantially higher HOTTIP levels, while patients with rs7158663 AA or GA genotypes indicated notably lower expression of MEG3 than GG genotype carriers.ConclusionIndividuals with genetic variants of HOTTIP rs1859168 and MEG3 rs7158663 might have an increased risk of NPC susceptibility and related clinicopathologic characteristics, potentially by affecting the expression of HOTTIP and MEG3.

Deciphering the role of non-coding RNAs SNHG18, HOXA11-AS, MEG3, and MDC1-AS1 in glioma patients: A combined experimental and computational study

BackgroundGliomas are brain tumours categorised into low-grade (I and II) and high-grade (III and IV). Unfortunately, patients with high-grade gliomas have a poor prognosis, which is why researchers are working to improve their management. One crucial area of study is the understanding of glioma tumorigenesis and progression. Recent research has shown that long non-coding RNAs (lncRNAs) play a potential role in this process. Material and methodsWe evaluated the expression of SNHG18, HOXA11-AS, MEG3, and MDC1-AS1 in 150 paraffin tissue block samples, including 37 low-grade gliomas, 58 high-grade gliomas, and 55 non-tumoural tissues. After RNA extraction and complementary DNA synthesis (cDNA), we used probe-based qPCR to evaluate the lncRNA expression level, followed by statistical analyses. ResultsThe qRT-PCR analysis revealed differential expression patterns of lncRNAs in tumour tissues compared to controls. In low-grade tumours, SNHG18 and HOXA11-AS were upregulated (SNHG18: 1.78 ± 0.21, p < 0.001; HOXA11-AS: 1.24 ± 0.60, p < 0.001), while MEG3 and MDC1-AS1 were downregulated (MEG3: 0.72 ± 0.17, p < 0.001; MDC1-AS1: 0.24 ± 0.18, p < 0.001). In high-grade tumours, SNHG18 and HOXA11-AS were further upregulated (SNHG18: 3.16 ± 0.88, p < 0.001; HOXA11-AS: 3.83 ± 0.82, p < 0.001), and MEG3 and MDC1-AS1 remained downregulated (MEG3: 0.49 ± 0.29, p < 0.001; MDC1-AS1: 0.15 ± 0.09, p < 0.001). The bioinformatic-based study conveyed that the alteration in lncRNAs expression leads to dysregulation of RNA Polymerase II, which is observed in glioblastoma. ConclusionOur results suggest that SNHG18 and HOXA11-AS (up-regulated) may act as oncogenes in high-grade gliomas. In contrast, the downregulation of MEG3 and MDC1-AS1 in high-grade gliomas could be related to tumour suppressor properties. Therefore, it could be assumed that the expression levels of these lncRNAs may serve as potential biomarkers for diagnostic and therapeutic purposes.

MEG3-Mediated Oral Squamous-Cell-Carcinoma-Derived Exosomal miR-421 Activates Angiogenesis by Targeting HS2ST1 in Vascular Endothelial Cells.

Exosomal microRNAs (miRNAs) from cancer cells play a key role in mediating the oral squamous cell carcinoma (OSCC) microenvironment. The objective of this study was to investigate how the long non-coding RNA (lncRNA) MEG3 affects OSCC angiogenesis through exosomal miR-421. Global miRNA microarray analysis and quantitative real-time PCR (qRT-PCR) were performed to determine the level of miRNAs in OSCC cell-derived exosomes. Cell migration, invasion, tube formation, immunohistochemistry, and hemoglobin concentrations were used to study the effects of exosomal miR-421 in angiogenesis. Western blotting was used to determine the expression level of HS2ST1 and VEGFR2-related downstream proteins. MiRNA array and qRT-PCR identified the upregulation of miR-421 in OSCC cell-derived exosomes. Furthermore, exosomal miR-421 can be taken up by human umbilical vein endothelial cells (HUVECs) and then target HS2ST1 through VEGF-mediated ERK and AKT phosphorylation, thereby promoting HUVEC migration, invasion, and tube formation. Additionally, forced expression of the lncRNA MEG3 in OSCC cells reduced exosomal miR-421 levels and then increased HS2ST1 expression, thereby reducing the VEGF/VEGFR2 pathway in HUVECs. Our results demonstrate a novel mechanism by which lncRNA MEG3 can act as a tumor suppressor and regulate endothelial angiogenesis through the exosomal miR-421/HS2ST1 axis, which provides a potential therapeutic strategy for OSCC angiogenesis.

Adenovirus 36 seropositivity is related to the expression of anti-adipogenic lncRNAs GAS5 and MEG3 in adipose tissue obtained from subjects with obesity.

Human Adenovirus D-36 (HAdV-D36) promotes adipogenesis in cellular and animal models and may contribute to the development of human obesity. Induction of PPARγ by HAdV-D36 seems to have a central role in the maintenance of adipogenic status. There is limited information about epigenetic mechanisms contributing to this process in human adipose tissue. This study evaluated the expression of lncRNAs (ADINR, GAS5 and MEG3) and miRNAs (miR-18a and miR-140) involved in the adipogenic process in visceral adipose tissue (VAT) of subjects with obesity with previous HAdV-D36 infection (seropositive) and unexposed (seronegative) subjects with obesity. Individuals with obesity were grouped according to the presence of antibodies against HAdV-D36 (Seropositive: HAdV-D36[+], n = 29; and Seronegative: HAdV-D36[-], n = 28). Additionally, a group of individuals without obesity (n = 17) was selected as a control group. The HAdV-D36 serology was carried out by ELISA. Biopsies of VAT were obtained during an elective and clinically indicated surgery (bariatric or cholecystectomy). RNA extraction from VAT was performed and the expression of PPARG and non-coding RNAs was evaluated by qPCR. HAdV-D36[+] individuals had lower expression of anti-adipogenic lncRNAs GAS5 (p = 0.016) and MEG3 (p = 0.035) compared with HAdV-D36[-] subjects with obesity. HAdV-D36[+] subjects also presented increased expression of the adipogenic miRNA miR-18a (p = 0.042), which has been reported to be modulated by GAS5 through a RNA sponging mechanism during adipogenic differentiation. Additionally, an inverse correlation of GAS5 with PPARG expression was observed (r = -0.917, p = 0.01). Our results suggest that HAdV-D36 is related to non-coding RNAs implicated in adipogenesis, representing a potential mechanism by which previous HAdV-D36 infection could be associated with the long-term maintenance of adipogenic status, probably through the GAS5/miR-18a axis.

Study of lncRNAs expression profile in the response to biological drugs in Psoriatic Arthritis: MEG3 could be a potential genomic biomarker of therapy efficacy

We aimed to identify an expression profile of lncRNAs potentially related to treatment response in Psoriatic arthritis (PsA) patients, to be used as potential genomic biomarkers predictors of drug treatment effectiveness. In addition, we evaluated a possible association between lncRNAs genetic variants and the response to therapy using the clinical parameter of Disease Activity Index. For the expression study, we collected 48 treated PsA patients, monitoring the treatment response for 12 months. We initially used PCR Array and, then, we validated the results with qRT-PCR. We also retrospectively genotyped 163 treated PsA patients. Firstly, we observed a significant difference in the expression level between Responder and non-Responder patients, of 4 lncRNAs in the group of PsA patients treated with TNFi and of 3 lncRNAs in the group of patients treated with IL17i. Then, we confirmed a significant decrease of MEG3 expression in non-Responder patients compared to Responders, also considering separately the single groups of patients treated with TNFi and IL17i. In addition, our results seem to highlight a potential dose-dependent effect of rs941576 (MEG3) variant allele on Disease Activity Index. Our study suggests a possible role of the lncRNA MEG3 in the treatment response to biological drugs.

MEG3 rs7158663 genetic polymorphism is associated with the risk of hepatocellular carcinoma

Recently, a meta-analysis has shown that a potentially functional genetic polymorphism (rs7158663 A > G) on the cancer-associated lncRNA MEG3 is associated with the risk of many types of cancer. Given the important role of MEG3 in the development of hepatocellular carcinoma (HCC), the current study evaluated the association of the rs7158663 genetic polymorphism with HCC risk. A total of 271 HCC patients and 267 healthy individuals were included in the current case-control study. Direct sequencing was used to detect the rs7158663 locus genotype of the included individuals. The case-control study showed that the MEG3 rs7158663 genetic polymorphism was associated with the increased risk of developing HCC [GA vs. GG: OR = 1.63, 95% CI = 1.14–2.34, p = 0.009; AA vs. GG: OR = 2.10, 95% CI = 1.10–4.08, p = 0.03; (GA + AA) vs. GG: OR = 1.70, 95% CI = 1.21–2.40, p = 0.003; A vs. G: OR = 1.53, 95% CI = 1.17–2.00, p = 0.002]. In addition, the genotype-tissue expression showed that the rs7158663 AA or GA genotype was associated with reduced MEG3 expression. Bioinformatic analysis showed that the rs7158663 genetic polymorphism not only affects the binding of transcription factors but also interacts with multiple genes through chromatin loops. In summary, the current findings suggest that the rs7158663 genetic polymorphism affecting MEG3 expression is associated with HCC risk and may serve as a marker of genetic susceptibility to HCC. However, the specific molecular mechanisms of the rs7158663 genetic polymorphism in the development of HCC need to be further revealed.

The long non-coding RNA Meg3 mediates imprinted gene expression during stem cell differentiation.

The imprinted Dlk1-Dio3 domain comprises the developmental genes Dlk1 and Rtl1, which are silenced on the maternal chromosome in different cell types. On this parental chromosome, the domain's imprinting control region activates a polycistron that produces the lncRNA Meg3 and many miRNAs (Mirg) and C/D-box snoRNAs (Rian). Although Meg3 lncRNA is nuclear and associates with the maternal chromosome, it is unknown whether it controls gene repression in cis. We created mouse embryonic stem cells (mESCs) that carry an ectopic poly(A) signal, reducing RNA levels along the polycistron, and generated Rian-/- mESCs as well. Upon ESC differentiation, we found that Meg3 lncRNA (but not Rian) is required for Dlk1 repression on the maternal chromosome. Biallelic Meg3 expression acquired through CRISPR-mediated demethylation of the paternal Meg3 promoter led to biallelic Dlk1 repression, and to loss of Rtl1 expression. lncRNA expression also correlated with DNA hypomethylation and CTCF binding at the 5'-side of Meg3. Using Capture Hi-C, we found that this creates a Topologically Associating Domain (TAD) organization that brings Meg3 close to Dlk1 on the maternal chromosome. The requirement of Meg3 for gene repression and TAD structure may explain how aberrant MEG3 expression at the human DLK1-DIO3 locus associates with imprinting disorders.

Possible role of lncRNAs in amelioration of Parkinson’s disease symptoms by transplantation of dopaminergic cells

Long non-coding RNAs (lncRNAs) are biomarkers for diagnosis and treatment of Parkinson’s disease (PD). Since dopaminergic cell transplantation is a clinical method to treat PD, this study investigated the effects of dopaminergic cell therapy on the expression of some lncRNAs and genes related to PD. In this study, Twenty-eight rats were randomly assigned to four experimental groups. The control group (Sal group) received saline injections. The Par group was a PD rat model with 6-hydroxydopamine (6-OHDA) injection in right striatum (ST). PD animals were transplanted by undifferentiated P19 stem cells (Par-E group), and P19-derived dopaminergic cells (Par-N group). Cell transplant effects were evaluated using behavioral tests (cylinder, open field, and rotarod tests), and histological methods (H&E and Nissl staining, and immunohistochemistry). Moreover, the expression of lncRNAs MALAT1, MEG3, and SNHG1, alongside specific neuronal (synaptophysin) and dopaminergic (tyrosine hydroxylase) markers was evaluated by qRT-PCR. Behavioral and histopathological examinations revealed that cell transplantation partially compensated dopaminergic cell degeneration in ST and substantia nigra (SN) of PD rats. The expression of MALAT1, SNHG1, and MEG3 was decreased in the ST of the Par group, while MEG3 and SNHG1 gene expression was increased in PBMC relative to the Sal group. In PBMC of the Par-N group, all three lncRNAs showed a reduction in their expression. Conversely, MALAT1 and SNHG1 expression was increased in ST tissue, while MEG3 gene expression was decreased compared to the Sal group. In conclusion, dopaminergic cell transplantation could change the lncRNAs expression. Furthermore, it partially improves symptoms in PD rats.

Multifaceted roles of Meg3 in cellular senescence and atherosclerosis

Background and aimsLong noncoding RNAs are involved in the pathogenesis of atherosclerosis. As long noncoding RNAs maternally expressed gene 3 (Meg3) prevents cellular senescence of hepatic vascular endothelium and obesity-induced insulin resistance, we decided to examine its role in cellular senescence and atherosclerosis. Methods and ResultsBy analyzing our data and human and mouse data from the Gene Expression Omnibus database, we found that Meg3 expression was reduced in humans and mice with cardiovascular disease, indicating its potential role in atherosclerosis. In Ldlr−/− mice fed a Western diet for 12 weeks, Meg3 silencing by chemically modified antisense oligonucleotides attenuated the formation of atherosclerotic lesions by 34.9% and 20.1% in male and female mice, respectively, revealed by en-face Oil Red O staining, which did not correlate with changes in plasma lipid profiles. Real-time quantitative PCR analysis of cellular senescence markers p21 and p16 revealed that Meg3 deficiency aggravates hepatic cellular senescence but not cellular senescence at aortic roots. Human Meg3 transgenic mice were generated to examine the role of Meg3 gain-of-function in the development of atherosclerosis induced by PCSK9 overexpression. Meg3 overexpression promotes atherosclerotic lesion formation by 29.2% in Meg3 knock-in mice independent of its effects on lipid profiles. Meg3 overexpression inhibits hepatic cellular senescence, while it promotes aortic cellular senescence likely by impairing mitochondrial function and delaying cell cycle progression. ConclusionsOur data demonstrate that Meg3 promotes the formation of atherosclerotic lesions independent of its effects on plasma lipid profiles. In addition, Meg3 regulates cellular senescence in a tissue-specific manner during atherosclerosis. Thus, we demonstrated that Meg3 has multifaceted roles in cellular senescence and atherosclerosis.

M6A-Mediated Upregulation of Imprinted in Prader-Willi Syndrome Induces Aberrant Apical-Basal Polarization and Oxidative Damage in RPE Cells.

To reveal the clinical significance, pathological involvement and molecular mechanism of imprinted in Prader-Willi syndrome (IPW) in RPE anomalies that contribute to AMD. IPW expression under pathological conditions were detected by microarrays and qPCR assays. In vitro cultured fetal RPE cells were used to study the pathogenicity induced by IPW overexpression and to analyze its upstream and downstream regulatory networks. We showed that IPW is upregulated in the macular RPE-choroid tissue of dry AMD patients and in fetal RPE cells under oxidative stress, inflammation and dedifferentiation. IPW overexpression in fetal RPE cells induced aberrant apical-basal polarization as shown by dysregulated polarized markers, disrupted tight and adherens junctions, and inhibited phagocytosis. IPW upregulation was also associated with RPE oxidative damages, as demonstrated by intracellular accumulation of reactive oxygen species, reduced cell proliferation, and accelerated cell apoptosis. Mechanically, N6-methyladenosine level of the IPW transcript regulated its stability with YTHDC1 as the reader. IPW mediated RPE features by suppressing MEG3 expression to sequester its inhibition on the AKT serine-threonine kinase (AKT)/mammalian target of rapamycin (mTOR) pathway. We also noticed that the mTOR inhibitor rapamycin suppresses the AKT/mTOR pathway to alleviate the IPW-induced RPE anomalies. We revealed that IPW overexpression in RPE induces aberrant apical-basal polarization and oxidative damages, thus contributing to AMD progression. We also annotated the upstream and downstream regulatory networks of IPW in RPE. Our findings shed new light on the molecular mechanisms of RPE dysfunctions, and indicate that IPW blockers may be a promising option to treat RPE abnormalities in AMD.

The Expression of TP53TG1, LINC00342, MALAT1, H19, and MEG3 Long Noncoding RNAs in Type 2 diabetes mellitus

Type 2 diabetes is a complex and multifactorial metabolic disorder. The frequency of type 2 diabetes has dramatically increased worldwide. Long noncoding RNAs play a regulatory role in pathological processes of type 2 diabetes. The aim of the study was to analyze TP53TG1, LINC00342, MALAT1, H19, and MEG3 lncRNAs in patients with type 2 diabetes and metabolic parameters, as well as the risk of diabetic retinopathy. Participants included 51 patients with diabetes and 70 healthy individuals. The expression of the TP53TG1 and LINC00342 genes was significantly decreased in the patients with diabetes compared to healthy individuals. MALAT1 gene expression was higher in diabetes patients. H19 gene expression was increased in the patients with diabetic retinopathy compared patients without retinopathy. TP53TG1, LINC00342, and MEG3 expression was decreased in patients with diabetic retinopathy and MALAT1 expression was increased. H19 is positively correlated with triglyceride levels; TP53TG1 and LINC00342 are positively correlated with HbA1c levels and fasting glucose levels. MALAT1 is negatively correlated with HDL levels and positively correlated with LDL levels. A decrease in the expression level of TP53TG1 and LINC00342 and an increase in the level of MALAT1 in diabetes, as well as an association with glycemic control, indicate the role of the studied noncoding RNAs in the development of type 2 diabetes mellitus and retinopathy and can be considered as candidates for early diagnosis of type 2 diabetes.

Overexpression of LncRNA MEG3 promotes ferroptosis and enhances chemotherapy sensitivity of hepatocellular carcinoma cells to cisplatin

To investigate the effect of overexpression of LncRNA MEG3 on proliferation, migration and cisplatin sensitivity of hepatoma cells HepG2 and LM3 and explore the underlying and mechanism. The expression of MEG3 in healthy individuals and patients with hepatocellular carcinoma (HCC) was analyzed by online bioinformatics analysis, and Real-time fluorescence quantitative PCR (qRT-PCR) was used to detect MEG3 expression in different HCC cell lines. A MEG3-overexpresing plasmid was transfected in HepG2 and LM3 cells, and the changes in cell proliferation and migration were examined using CCK8 assay and scratch assay. CCK8 assay was used to determine the inhibitory rate of cisplatin on the transfected cells. A reactive oxygen species (ROS) fluorescence probe (DCFH-DA) and malondialdehyde (MDA) kit were used to assess the changes in ROS production and MDA level in the cells. Western blotting was performed to detect the expression levels of ferroptosis-related proteins glutathione peroxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1). The expression of MEG3 was significantly lower in HCC cells than in LO2 cells, which was consistent with the results of bioinformatic analysis (P < 0.05). Overexpression of MEG3 in the HCC cell lines significantly suppressed cell proliferation and migration (P < 0.05), increased the cell inhibition rate of cisplatin (P < 0.05), enhanced cellular ROS production and increased MDA levels in the cells (P < 0.05). MEG3 overexpression significantly decreased the expressions of GPX4 and FTH1 in the HCC cell lines. The expression of MEG3 is decreased in HCC cells, and its overexpression inhibits proliferation and migration and enhances cisplatin sensitivity of HCC cells by promoting ferroptosis of the cells.

LncRNA MEG3 suppresses erastin-induced ferroptosis of chondrocytes via regulating miR-885-5p/SLC7A11 axis.

Ferroptosis is involved in osteoarthritis development; however, the roles of long noncoding RNAs (lncRNAs), including lncRNA MEG3, in the regulation of ferroptosis in osteoarthritis are still unclear. In this study, qRT‒PCR and Western blotting assays were used to detect the expression of lncRNA MEG3, miR-885-5p, SLC7A11 and GPX4; MDA and CCK-8 assays were applied to analyse cellular MDA levels and cell viability, respectively. Erastin elevated cellular MDA levels and decreased the viability of chondrocytes and the erastin-induced decline in cell viability was reversed by a ferroptosis inhibitor (ferrostatin-1). Erastin downregulated lncRNA MEG3, SLC7A11 and GPX4 and upregulated miR-885-5p. Silencing of lncRNA MEG3 increased miR-885-5p and downregulated SLC7A11 and GPX4 and further sensitized chondrocytes to erastin-induced ferroptosis. In contrast, overexpression of lncRNA MEG3 had opposite effects. Dual luciferase assays confirmed binding between lncRNA MEG3 and miR-885-5p and between miR-885-5p and the 3'UTR of SLC7A11. In the synovial fluids from patients with osteoarthritis compared with synovial fluids from normal controls, the RNA levels of lncRNA MEG3 and SLC7A11 were decreased and the miR-885-5p expression level was increased. Our findings indicated that lncRNA MEG3 overexpression alleviated ferroptosis in chondrocytes by affecting the miR-885-5p/SLC7A11 signalling pathway.

The ceRNA Mechanism of lncRNA MEG3/miR-21-5p/SPRY2 in Cell Proliferation and Apoptosis in Bladder Cancer.

Bladder cancer (BC) is the second most common genitourinary malignancy. Long noncoding RNA (lncRNA) is implicated in BC progression. This study delved into the underlying mechanism of lncRNA MEG3 in BC. Bioinformatics analysis predicted the expression of lncRNA MEG3, its association with the survival of BC patients, its subcellular localization, and its binding sites with miR-21-5p. Differentially expressed genes (DEGs) in the GSE13507 chip were analyzed using GEOexplorer, downstream targets of miR-21-5p were predicted from databases, and the overlapping genes were analyzed by the website Venny2.1 (https://bioinfogp.cnb.csic.es/tools/venny/index.html); their impacts on patient survival were analyzed by the Starbase database. The expression of SPRY2 and TGFBI associated with patient survival was analyzed in TCGA. RT-qPCR and western blot were performed to detect levels of MEG3, miR-21-5p, and SPRY2 in BC/SV-HUC-1 cells. Malignant biological behaviors of BC cells were detected using CCK8, flow cytometry, and Transwell assays. RNA pull-down and dual-luciferase assays were employed to verify the binding relationship of miR-21-5p with MEG3 and SPRY2. MEG3 was found to be lowly expressed in BC cells and mainly distributed in the cytoplasm. Over-expression of MEG3 was found to inhibit BC cell activity, promote apoptosis, and reduce invasion and migration. miR-21-5p was found to be highly expressed in BC cells, and its down-regulation was found to inhibit the malignant behavior of BC cells. Over-expression of miR-21-5p was found to reverse the effect of pcDNA3.1-MEG3 on BC cells. MEG3 was found to competitively bind to miR-21-5p as a ceRNA to promote SPRY2 levels. LncRNA MEG3 promotes SPRY2 expression by competitively binding to miR-21-5p, thereby inhibiting proliferation and promoting apoptosis of BC cells.

HGF facilitates methylation of MEG3, potentially implicated in vemurafenib resistance in melanoma.

Melanoma, a frequently encountered cutaneous malignancy characterized by a poor prognosis, persists in presenting formidable challenges despite the advancement in molecularly targeted drugs designed to improve survival rates significantly. Unfortunately, as more therapeutic choices have developed over time, the gradual emergence of drug resistance has become a notable impediment to the effectiveness of these therapeutic interventions. The hepatocyte growth factor (HGF)/c-met signaling pathway has attracted considerable attention, associated with drug resistance stemming from multiple potential mutations within the c-met gene. The activation of the HGF/c-met pathway operates in an autocrine manner in melanoma. Notably, a key player in the regulatory orchestration of HGF/c-met activation is the long non-coding RNA MEG3. Melanoma tissues were collected to measure MEG3 expression. In vitro validation was performed on MEG3 to prove its oncogenic roles. Bioinformatic analyses were conducted on the TCGA database to build the MEG3-related score. The immune characteristics and mutation features of the MEG3-related score were explored. We revealed a negative correlation between HGF and MEG3. In melanoma cells, HGF inhibited MEG3 expression by augmenting the methylation of the MEG3 promoter. Significantly, MEG3 exhibits a suppressive impact on the proliferation and migration of melanoma cells, concurrently inhibiting c-met expression. Moreover, a predictive model centered around MEG3 demonstrates notable efficacy in forecasting critical prognostic indicators, immunological profiles, and mutation statuses among melanoma patients. The present study highlights the potential of MEG3 as a pivotal regulator of c-met, establishing it as a promising candidate for targeted drug development in the ongoing pursuit of effective therapeutic interventions.

Expression of long noncoding RNA MEG3 and microRNA-302b-3p in colon cancer: Correlation with clinical stage and value in predicing prognosis after surgical treatment

Expression of long noncoding RNA MEG3 and microRNA-302b-3p in colon cancer: Correlation with clinical stage and value in predicing prognosis after surgical treatment

MALAT1 and MEG3 genes expression in non-alcoholic fatty liver disease in type 2 diabetes mellitus patients: a case-control study

ABSTRACT Aim of the study This study aims to investigate the nonalcoholic fatty liver disease (NAFLD) serum molecular profile among individuals diagnosed with type 2 diabetes (T2DM). Methods In this observational case-control investigation, 120 participants were included and subdivided forming 4 different groups as follows: group І: NAFLD non diabetic individuals, group ІІ: T2DM without NAFLD patients, group III: NAFLD diabetic patients and group IV: healthy control. MALAT1 and MEG3 expression in serum from all groups was measured. Results Expression of MALAT1 was upregulated in NAFLD and diabetic patients (p = 0.037 and 0.033 respectively). The cutoff value was determined for MALAT1 expression in NAFLD and diabetic by the ROC curve and was > 0.54 and > 0.67 respectively. By multivariate analysis, the only reliable indicator for MALAT1 expression in NAFLD and diabetics was determined to be ESR. Furthermore, we found that NAFLD patients showed greater MEG3 expression than those with T2DM (p = 0.033). Conclusion Expression of MALAT1 was upregulated in NAFLD and T2DM indicating that it might be an early diagnostic marker for both diseases and helps in the development of novel therapeutic agents. Moreover, MEG3 expression was higher among NAFLD patients than those NAFLD patients with T2DM, which suggests the feasibility of decreased MEG3 expression could be a viable predictive biomarker for early T2DM detection among NAFLD-diagnosed patients.