LncRNA MEG3 regulates ferroptosis of lens epithelial cells via PTBP1/GPX4 axis to participate in age-related cataract.

Age-related cataract (ARC) is regarded as the principal cause of vision impairment among the aged. The regulatory role of long noncoding RNAs (LncRNAs) in ARC remains unclear. The lncRNA maternally expressed gene 3 (MEG3) has been reported to promote ARC progression, and the underlying mechanism was further investigated in this study. Lens epithelium samples were collected to verify the expression of MEG3. Lens epithelial cells (LECs) were treated with H2O2 to mimic microenvironment of ARC in vitro. Cell viability, reactive oxygen species, and ferroptosis were evaluated during the in viro experiments. In the present work, lncRNA MEG3 was highly expressed in ARC group, compared with normal group. MEG3 was induced, cell viability and glutathione peroxidase 4 (GPX4) level were inhibited, and ferroptosis was promoted in H2O2 treated LECs. LncRNA MEG3 silence reversed the effects of H2O2 on viability and ferroptosis in LECs. Thereafter, lncRNA MEG3 was found to bind to PTBP1 for GPX4 degradation. Silencing of GPX4 reversed the regulation of lncRNA MEG3 inhibition in H2O2-treated LECs. To sum up, lncRNA MEG3 exhibited high expression in ARC. In H2O2-induced LECs, inhibition of lncRNA MEG3 accelerated cell viability and repressed ferroptosis by interaction with PTBP1 for GPX4 messenger RNA decay. Targeting lncRNA MEG3 may be a novel treatment of ARC.

A possible role of lncRNA MEG3 and lncRNA MAFG-AS1 on miRNA 147-b in the pathogenesis of Behcet's disease.

Behcet's disease (BD) is a multisystem disease with altered Toll-like receptors (TLRs) on macrophages. Long noncoding RNA Maternally expressed gene 3 (lncRNA MEG3) and lncRNA Musculoaponeurotic fibrosarcoma oncogene family, protein G antisense 1 (MAFG-AS1) are regulators of microRNA (miRNA) 147-b, which is induced upon TLR stimulation. We included fifty BD patients, and fifty age and sex-matched controls. Real-time polymerase chain reaction (PCR) was used to measure the expression levels of serum lncRNA MEG3, lncRNA MAFG-AS1, and miRNA 147-b. LncRNA MEG3 and lncRNA MAFG-AS1 were significantly downregulated while miRNA 147-b was significantly upregulated in the BD patients' serum compared to the controls with p-value <0.001. Receiver operation characteristics (ROC) curve analysis revealed that the three biomarkers can discriminate between BD and control subjects with 76%, 100%, and 70% sensitivity respectively, and 100% specificity for all of them. There was a lower expression level of lnc RNA MEG3 among patients who had new eye involvement in the last month in comparison to those without new eye involvement (p-value=0.017). So, LncRNA MEG3, lncRNA MAFG-AS1, and miRNA147-b are promising diagnostic markers and therapeutic targets for BD patients. LncRNA MEG3 can be used as a predictor for new BD ocular involvement.

RhoGDIß inhibition via miR-200c/AUF1/SOX2/miR-137 axis contributed to lncRNA MEG3 downregulation-mediated malignant transformation of human bronchial epithelial cells.

Nickel pollution is a recognized factor contributing to lung cancer. Understanding the molecular mechanisms of its carcinogenic effects is crucial for lung cancer prevention and treatment. Our previous research identified the downregulation of a long noncoding RNA, maternally expressed gene 3 (MEG3), as a key factor in transforming human bronchial epithelial cells (HBECs) into malignant cells following nickel exposure. In our study, we found that deletion of MEG3 also reduced the expression of RhoGDIß. Notably, artificially increasing RhoGDIß levels counteracted the malignant transformation caused by MEG3 deletion in HBECs. This indicates that the reduction in RhoGDIß contributes to the transformation of HBECs due to MEG3 deletion. Further exploration revealed that MEG3 downregulation led to enhanced c-Jun activity, which in turn promoted miR-200c transcription. High levels of miR-200c subsequently increased the translation of AUF1 protein, stabilizing SOX2 messenger RNA (mRNA). This stabilization affected the regulation of miR-137, SP-1 protein translation, and the suppression of RhoGDIß mRNA transcription and protein expression, leading to cell transformation. Our study underscores the co-regulation of RhoGDIß expression by long noncoding RNA MEG3, multiple microRNAs (miR-200c and miR-137), and RNA-regulated transcription factors (c-Jun, SOX2, and SP1). This intricate network of molecular events sheds light on the nature of lung tumorigenesis. These novel findings pave the way for developing targeted strategies for the prevention and treatment of human lung cancer based on the MEG3/RhoGDIß pathway.

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

BACKGROUND: 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. METHODS: 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. RESULT: 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. CONCLUSION: Our findings indicated that lncRNA MEG3 overexpression alleviated ferroptosis in chondrocytes by affecting the miR-885-5p/SLC7A11 signalling pathway.

HNRNPA2B1-mediated m6A modification of lncRNA MEG3 facilitates tumorigenesis and metastasis of non-small cell lung cancer by regulating miR-21-5p/PTEN axis.

BACKGROUND: Accumulating data indicate that N6-methyladenosine (m6A) RNA methylation and lncRNA deregulation act crucial roles in cancer progression. Heterogeneous nuclear ribonucleoprotein A2B1 (HNRNPA2B1) as an m6A "reader" has been reported to be an oncogene in multiple malignancies. We herein aimed to elucidate the role and underlying mechanism by which HNRNPA2B1-mediated m6A modification of lncRNAs contributes to non-small cell lung cancer (NSCLC). METHODS: The expression levels of HNRNPA2B1 and their association with the clinicopathological characteristics and prognosis in NSCLC were determined by RT-qPCR, Western blot, immunohistochemistry and TCGA dataset. Then, the role of HNRNPA2B1 in NSCLC cells was assessed by in vitro functional experiments and in vivo tumorigenesis and lung metastasis models. HNRNPA2B1-mediated m6A modification of lncRNAs was screened by m6A-lncRNA epi-transcriptomic microarray and verified by methylated RNA immunoprecipitation (Me-RIP). The lncRNA MEG3-specific binding with miR-21-5p was evaluated by luciferase gene report and RIP assays. The effects of HNRNPA2B1 and (or) lncRNA MEG3 on miR-21-5p/PTEN/PI3K/AKT signaling were examined by RT-qPCR and Western blot analyses. RESULTS: We found that upregulation of HNRNPA2B1 was associated with distant metastasis and poor survival, representing an independent prognostic factor in patients with NSCLC. Knockdown of HNRNPA2B1 impaired cell proliferation and metastasis in vitro and in vivo, whereas ectopic expression of HNRNPA2B1 possessed the opposite effects. Mechanical investigations revealed that lncRNA MEG3 was an m6A target of HNRNPA2B1 and inhibition of HNRNPA2B1 decreased MEG3 m6A levels but increased its mRNA levels. Furthermore, lncRNA MEG3 could act as a sponge of miR-21-5p to upregulate PTEN and inactivate PI3K/AKT signaling, leading to the suppression of cell proliferation and invasion. Low expression of lncRNA MEG3 or elevated expression of miR-21-5p indicated poor survival in patients with NSCLC. CONCLUSIONS: Our findings uncover that HNRNPA2B1-mediated m6A modification of lncRNA MEG3 promotes tumorigenesis and metastasis of NSCLC cells by regulating miR-21-5p/PTEN axis and may provide a therapeutic target for NSCLC.

IL-27 induces autophagy through regulation of the DNMT1/lncRNA MEG3/ERK/p38 axis to reduce pulmonary fibrosis.

PURPOSE: Previous studies have shown that interleukin-27 (IL-27) can reduce bleomycin (BLM)-induced pulmonary fibrosis (PF). However, the underlying mechanism by which IL-27 attenuates PF is not fully clear. METHODS: In this research, we used BLM to construct a PF mouse model, and MRC-5 cells stimulated by transforming growth factor-ß1 (TGF-ß1) were used to construct a PF model in vitro. The lung tissue status was observed by Masson and hematoxylin and eosin (HE) staining. To detect gene expression, RT‒qPCR was used. The protein levels were detected by western blotting and immunofluorescence staining. EdU and ELISA were used to detect cell proliferation viability and hydroxyproline (HYP) content, respectively. RESULTS: Aberrant IL-27 expression was observed in BLM-induced mouse lung tissues, and the use of IL-27 attenuated mouse lung tissue fibrosis. TGF-ß1 induced autophagy inhibition in MRC-5 cells, and IL-27 alleviated MRC-5 cell fibrosis by activating autophagy. The mechanism is inhibition of DNA methyltransferase 1 (DNMT1)-mediated lncRNA MEG3 methylation and ERK/p38 signaling pathway activation. Overexpression of DNMT1, knockdown of lncRNA MEG3, autophagy inhibitor or ERK/p38 signaling pathway inhibitors reversed the positive effect of IL-27 in a lung fibrosis model in vitro. CONCLUSION: In conclusion, our study shows that IL-27 upregulates MEG3 expression through inhibition of DNMT1-mediated lncRNA MEG3 promoter methylation, which in turn inhibits ERK/p38 signaling pathway-induced autophagy and attenuates BLM-induced PF, providing a contribution to the elucidation of the potential mechanisms by which IL-27 attenuates PF.

Upregulation LncRNA MEG3 expression suppresses proliferation and metastasis in melanoma via miR-208/SOX4.

Long non-coding RNAs (lncRNAs) regulate gene expression and play a significant role in cancer progression. Previously, downregulation of lncRNA MEG3 was shown to associate with poor clinical outcomes in melanoma patients. The basis for this association has not been described and the aims of this study were to identify a role for lncRNA MEG3 in melanoma and to describe its regulatory mechanism of action. RT-qPCR was used to detect lncRNA MEG3 expression in melanoma cells and tissues. Luciferase reporter assays were used to identify lncRNA MEG3 downstream targets. Melanoma cells were transfected with various expression vectors and these transfected cells were assessed for; migration, colony formation, proliferation, in vivo tumorigenesis, and metastatic potential. Melanoma cell lines were found to be sensitive to lncRNA MEG3 expression levels and overexpression was found to inhibit melanoma cell proliferation and invasion, both in vitro and in vivo. Luciferase reporter assays identified miR-208 and SOX4 as downstream targets of lncRNA MEG3. Overexpression of miR-208 and silencing of SOX4 rescued invasion and proliferation by cells that overexpressed lncRNA MEG3. Moreover, lncRNA MEG3 inhibited cancer stem cell differentiation and suppressed melanoma progression and metastasis through inhibition of miR-208 by SOX4.

LncRNA-MEG3 attenuates hyperglycemia-induced damage by enhancing mitochondrial translocation of HSP90A in the primary hippocampal neurons.

The diabetic cognitive impairments are associated with high-glucose (HG)-induced mitochondrial dysfunctions in the brain. Our previous studies demonstrated that long non-coding RNA (lncRNA)-MEG3 alleviates diabetic cognitive impairments. However, the underlying mechanism has still remained elusive. Therefore, this study was designed to investigate whether the mitochondrial translocation of HSP90A and its phosphorylation are involved in lncRNA-MEG3-mediated neuroprotective effects of mitochondrial functions in HG-treated primary hippocampal neurons and diabetic rats. The primary hippocampal neurons were exposed to 75 mM glucose for 72 h to establish a HG model in vitro. Firstly, the RNA pull-down and RNA immunoprecipitation (RIP) assays clearly indicated that lncRNA-MEG3-associated mitochondrial proteins were Annexin A2, HSP90A, and Plectin. Although HG promoted the mitochondrial translocation of HSP90A and Annexin A2, lncRNA-MEG3 over-expression only enhanced the mitochondrial translocation of HSP90A, rather than Annexin A2, in the primary hippocampal neurons treated with or without HG. Meanwhile, Plectin mediated the mitochondrial localization of lncRNA-MEG3 and HSP90A. Furthermore, HSP90A threonine phosphorylation participated in regulating mitochondrial translocation of HSP90A, and lncRNA-MEG3 also enhanced mitochondrial translocation of HSP90A through suppressing HSP90A threonine phosphorylation. Finally, the anti-apoptotic role of mitochondrial translocation of HSP90A was found to be associated with inhibiting death receptor 5 (DR5) in HG-treated primary hippocampal neurons and diabetic rats. Taken together, lncRNA-MEG3 could improve mitochondrial functions in HG-exposed primary hippocampal neurons, and the underlying mechanisms were involved in enhanced mitochondrial translocation of HSP90A via suppressing HSP90A threonine phosphorylation, which may reveal a potential therapeutic target for diabetic cognitive impairments.

The Transgene Expression of the Immature Form of the HCV Core Protein (C191) and the LncRNA MEG3 Increases Apoptosis in HepG2 Cells.

Long non-coding RNAs (lncRNAs) are regulated in cancer cells, including lncRNA MEG3, which is downregulated in Hepatocellular Carcinoma (HCC). In addition, hepatitis C virus (HCV) core proteins are known to dysregulate important cellular pathways that are linked to HCC development. In this study, we were interested in evaluating the overexpression of lncRNA MEG3, either alone or in combination with two forms of HCV core protein (C173 and C191) in HepG2 cells. Cell viability was assessed by MTT assay. Transcripts' levels of key genes known to be regulated in HCC, such as p53, DNMT1, miRNA152, TGF-b, and BCL-2, were measured by qRT-PCR. Protein expression levels of caspase-3 and MKI67 were determined by immunocytochemistry and apoptosis assays. The co-expression of lncRNA MEG3 and C191 resulted in a marked increase and accumulation of dead cells and a reduction in cell viability. In addition, a marked increase in the expression of tumor suppressor genes (p53 and miRNA152), as well as a marked decrease in the expression of oncogenes (DNMT1, BCL2, and TGF-b), were detected. Moreover, apoptosis assay results revealed a significant increase in total apoptosis (early and late). Finally, immunocytochemistry results detected a significant increase in apoptotic marker caspase-3 and a decrease in tumor marker MKI67. In this study, transgene expression of C191 and lncRNA MEG3 showed induction in apoptosis in HepG2 cells greater than the expression of each one alone. These results suggest potential anticancer characteristics.

Long noncoding RNA MEG3 expressed in human dental pulp regulates LPS-Induced inflammation and odontogenic differentiation in pulpitis.

Pulpitis refers to inflammation of the inner pulp by invading microbes, and tissue repair occurs due to odontogenic differentiation of human dental pulp cells (hDPCs) with multidifferentiation potential. Long noncoding RNAs (lncRNAs) can modulate numerous pathological and biological processes; however, the role of lncRNAs in the inflammation and regeneration of the dentin-pulp complex in pulpitis is unclear. Here, we performed high-throughput sequencing to identify differentially expressed lncRNAs between human normal and inflamed pulp and concluded that lncMEG3 (lncRNA maternally expressed gene 3, MEG3) was significantly upregulated in both inflamed pulp and LPS-treated hDPCs. MEG3 expression in the pulp tissue was detected using the RNAscope® technique. RNA pulldown assays identified the MEG3-interacting proteins and the potential mechanisms. With MEG3 knockdown, we investigated the role of MEG3 in the secretion of inflammatory cytokines in LPS-treated hDPCs and odontogenic differentiation of hDPCs. MEG3 downregulation inhibited the secretion of TNF-α, IL-1ß and IL-6 in LPS-treated hDPCs, and the p38/MAPK signaling pathway may be related to this effect. MEG3 knockdown promoted odontogenic differentiation of hDPCs by regulating the Wnt/ß-catenin signaling pathway. Our study suggested that MEG3 has a negative effect on inflammation and regeneration of the dentin-pulp complex in pulpitis.

LncRNA MEG3 restrained pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway-mediated autophagy.

Long noncoding RNA maternally expressed gene 3 (lncRNA MEG3) was down-regulated in pulmonary fibrosis of rats induced by Nickel oxide nanoparticles (NiO NPs), while the downstream regulatory mechanisms of MEG3 remain unclear. This study aimed to investigate the relationship among MEG3, Hedgehog (Hh) signaling pathway and autophagy in pulmonary fibrosis caused by NiO NPs. The pulmonary fibrosis model in rats was constructed by intratracheal instillation of 0.015, 0.06, and 0.24 mg/kg NiO NPs twice a week for 9 weeks. Collagen deposition model was established by treating A549 cells with 25, 50, and 100 µg/mL NiO NPs for 24 h. Our results indicated that NiO NPs activated Hh pathway, down-regulated the expression of MEG3, and reduced autophagy activity in vivo and in vitro. Meanwhile, the autophagy process was promoted by Hh pathway inhibitor (CDG-0449), while the collagen formation in A549 cells was reduced by autophagy activator (Rapamycin). Furthermore, the overexpressed MEG3 inhibited the activation of Hh pathway, resulting in autophagy activity enhancement along with collagen formation reduction. In summary, lncRNA MEG3 can restrain pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway-mediated autophagy, which may serve as a potential therapeutic strategy for pulmonary fibrosis.

LncRNA MEG3 ameliorates NiO nanoparticles-induced pulmonary inflammatory damage via suppressing the p38 mitogen activated protein kinases pathway.

The lung inflammatory damage could result from the nickel oxide nanoparticles (NiO NPs), in which the underlying mechanism is still unclear. This article explored the roles of long noncoding RNA maternally expressed gene 3 (lncRNA MEG3) and p38 mitogen activated protein kinases (p38 MAPK) pathway in pulmonary inflammatory injury induced by NiO NPs. Wistar rats were treated with NiO NPs suspensions (0.015, 0.06, and 0.24 mg/kg) by intratracheal instillation twice-weekly for 9 weeks. Meanwhile, A549 cells were treated with NiO NPs suspensions (25, 50, and 100 µg/ml) for 24 h. It can be concluded that the NiO NPs did trigger pulmonary inflammatory damage, which was confirmed by the histopathological examination, abnormal changes of inflammatory cells and inflammatory cytokines (IL-1ß, IL-6, TGF-ß1, TNF-α, IFN-γ, IL-10, CXCL-1 and CXCL-2) in bronchoalveolar lavage fluid (BALF), pulmonary tissue and cell culture supernatant. Furthermore, NiO NPs activated the p38 MAPK pathway and downregulated MEG3 in vivo and in vitro. However, p38 MAPK pathway inhibitor (10 µM SB203580) reversed the alterations in the expression levels of inflammatory cytokines induced by NiO NPs. Meanwhile, over-expressed MEG3 significantly suppressed NiO NPs-induced p38 MAPK pathway activation and inflammatory cytokines changes. Overall, the above results proved that over-expression of lncRNA MEG3 reduced NiO NPs-induced inflammatory damage by preventing the activation of p38 MAPK pathway.

The lncRNA MEG3/miR-16-5p/VGLL4 regulatory axis is involved in etoposide-induced senescence of tumor cells.

BACKGROUND: The senescence of tumor cells is an important tumor suppressor mechanism. The present study aimed to investigate the role of long non-coding RNA (lncRNA) MEG3 (maternally expressed gene 3) in the senescence process of tumor cells and its potential molecular mechanism by competitively binding with microRNA miR-16-5p to regulate the expression of VGLL4 (encoding vestigial like family member 4). METHODS: We used etoposide to construct senescence models of tumor cells. The degree of cellular senescence was detected by senescence-associated ß-galactosidase, cell cycle and senescence-associated secretory phenotype. The expression of lncRNA MEG3, miR-16-5p and VGLL4 in senescent or non-senescent cells was evaluated using a quantitative real-time reverse transcriptase-PCR (qRT-PCR) or western blotting. Dual luciferase reporter assays were used to detect the binding of miR-16-5p to lncRNA MEG3 and VGLL4. The mRNA and protein expression levels of senescence-related markers (p53, p21 and p16) were detected using qRT-PCR or western blotting. RESULTS: Compared to the control group, the expression of lncRNA MEG3 and VGLL4 was significantly up-regulated in senescent cells. Knockdown of lncRNA MEG3 and VGLL4 reduced the degree of senescence and the expression of p21 and p16. lncRNA MEG3 interfered with the expression of miR-16-5p in senescent A549 and MCF-7 cells. The expression of VGLL4 was regulated by miR-16-5p in senescent A549 and MCF-7 cells. lncRNA MEG3 participated in the senescent progress of tumor cells induced by etoposide via the miR-16-5p/VGLL4 axis. CONCLUSIONS: The present study has confirmed the regulatory role of the lncRNA MEG3/miR-16-5p/VGLL4 axis in the low-dose etoposide-induced tumor cell senescence model, which has potential clinical application with respect to treating malignant tumors.

LncRNA MEG3 inhibits the proliferation of neural stem cells after ischemic stroke via the miR-493-5P/MIF axis.

OBJECTIVE: The proliferation of neural stem cells (NSCs1), or lack thereof, can have profound effects on brain tissue remodeling for ischemic stroke (IS2). In this study, we aimed to reveal the influence of the lncRNA MEG3/miR-493-5p/MIF axis on NSC proliferation after IS. METHODS: We established an oxygen glucose-deprivation/reoxygenation (OGD/R3) in vitro model of IS in NSCs. We evaluated NSC isolation efficiency and proliferation by NESTIN, SOX2, and PCNA immunofluorescence staining. MEG3 and miR-493-5P levels were assessed by quantitative real-time polymerase chain reaction (qRT-PCR4). Changes in MIF protein expression levels were analyzed using Western blotting. We then evaluated the role of MEG3 and miR-493-5p by transfection of si-MEG3, a miR-493-5p mimic, or miR-493-5p inhibitor. NSC proliferation was quantified using Cell Counting Kit-8 analysis. RESULTS: NESTIN and SOX2 were co-expressed in endogenous NSCs. Following OGD/R, MEG3 and miR-493-5P were significantly upregulated in NSCs, while MIF levels decreased and proliferation was inhibited. Knockdown of MEG3 inhibited miR-493-5p and rescued expression of MIF and PCNA, restoring cellular proliferation levels. In NSCs transfected with a miR-493-5p mimic or inhibitor, MIF levels were down- or upregulated, respectively. Consistently, transfection of a miR-493-5p mimic reduced NSC proliferation, while transfection with a miR-493-5p inhibitor or si-MEG3 rescued the inhibitory effect of OGD/R on NSC proliferation. After co-transfection of si-MEG3 and a miR-493-5p mimic of OGD/R-induced NSCs, levels of PCNA, an indicator of cellular proliferation, were significantly reduced. Conclusion MEG3 inhibits NSC proliferation of after IS via positive regulation of miR-493-5p and potential subsequent downregulation of MIF.

Long non-coding RNA MEG3 mediates the miR-149-3p/FOXP3 axis by reducing p53 ubiquitination to exert a suppressive effect on regulatory T cell differentiation and immune escape in esophageal cancer.

BACKGROUND: Long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) has been implicated in the progression of esophageal cancer (EC). However, the specific mechanism of the involvement of MEG3 in EC development in relation to the regulation of immune escape remains uncertain. Thus, the aim of the current study was to investigate the effect of MEG3 on EC via microRNA-149-3p (miR-149-3p). METHODS: Gain- and loss-of-function experiments were initially performed in EC cells in addition to the establishment of a 4-nitroquinoline 1-oxide-induced EC mouse model aimed at evaluating the respective roles of forkhead box P3 (FOXP3), MEG3, miR-149-3p, mouse double minute 2 homolog (MDM2) and p53 in T cell differentiation and immune escape observed in EC. RESULTS: EC tissues were found to exhibit upregulated FOXP3 and MDM2 while MEG3, p53 and miR-149-3p were all downregulated. FOXP3 was confirmed to be a target gene of miR-149-3p with our data suggesting it reduced p53 ubiquitination and degradation by means of inhibiting MDM2. P53 was enriched in the promoter of miR-149-3p to upregulate miR-149-3p. The overexpression of MEG3, p53 or miR-149-3p or silencing FOXP3 was associated with a decline in CD25+FOXP3+CD4+ T cells, IL-10+CD4+ T cells and IL-4+CD4+ T cells in spleen tissues, IL-4, and IL-10 levels as well as C-myc, N-myc and Ki-67 expression in EC mice. CONCLUSION: Collectively, MEG3 decreased FOXP3 expression and resulted in repressed regulatory T cell differentiation and immune escape in EC mice by upregulating miR-149-3p via MDM2-mediated p53.

LncRNA MEG3 suppresses PI3K/AKT/mTOR signalling pathway to enhance autophagy and inhibit inflammation in TNF-α-treated keratinocytes and psoriatic mice.

BACKGROUND: Psoriasis is a common chronic inflammatory skin disorder that causes patches of thick red skin and silvery scales and affects 1-3% of the population, which reduces patient's quality of life. Understanding the pathogenesis of psoriasis is crucial for developing novel therapeutic strategies. METHODS: HaCaT and NHEK cells were treated with TNF-α in vitro. A mouse model of psoriasis was established by topical imiquimod application on back skin. LncRNA MEG3 was cloned into the pcDNA3.1 vector and transfected in TNF-α-treated HaCaT and NHEK cells to overexpress its expression. Liposome-encapsulated pcDNA3.1-MEG3 was injected into imiquimod-treated mice via tail vein. RT-qPCR and western blot assays were used to examine the expression of lncRNA MEG3, IL-6, IL-8, IFN-γ, IL-1ß, LC3, Beclin 1, p62, p-p65, p65, NLRP3, p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR respectively. The secretion of IL-6, IL-8, IFN-γ and IL-1ß was determined using ELISA assay. Immunofluorescence and immunohistochemistry methods were performed for analyzing the expression of LC3 and NLRP3 in cells and skin tissues respectively. LY294002 was used to block the PI3K/AKT/mTOR signalling. MTT assay was applied to test the toxicity of LY294002 to HaCaT and NHEK cells. RESULTS: LncRNA MEG3 expression levels were downregulated in TNF-α-treated HaCaT and NHEK cells and skin tissues of psoriatic mice model. TNF-α treatment enhanced inflammation and suppressed autophagy in HaCaT and NHEK cells, which were largely reversed by overexpression of lncRNA MEG3. Autophagy puncta and NLRP3 inflammasome assembly showed the same patterns with the expression of inflammation and autophagy markers in TNF-α-treated HaCaT and NHEK cells with or without lncRNA MEG3 overexpression. TNF-α-induced activation of the PI3K/AKT/mTOR signalling was abolished by lncRNA MEG3 overexpression in HaCaT and NHEK cells. Blocking the PI3K/AKT/mTOR signalling inhibited TNF-α-induced inflammation and restored autophagy level in TNF-α-treated HaCaT and NHEK cells. Overexpression of lncRNA MEG3 suppressed inflammation, promoted autophagy and inhibited the activation of the PI3K/AKT/mTOR signalling in a mouse model of psoriasis. CONCLUSION: LncRNA MEG3 facilitates autophagy and suppresses inflammation in TNF-α-treated keratinocytes and psoriatic mice, which is dependent on the PI3K/AKT/mTOR signalling pathway. Our study enhances the understanding of psoriasis and provides potential therapeutic targets for psoriasis.

Downregulation of lncRNA MEG3 is involved in Parkinson's disease.

BACKGROUND: Long non-coding RNA (lncRNA) MEG3 regulates human cancers, while its role in Parkinson's disease (PD) is unknown. The present study explored the involvement of MEG3 in PD. METHODS: This study enrolled PD patients (n = 79) and healthy controls (n = 62) who were admitted to the Second Affiliated Hospital of Nanchang University from May 2016 to March 2018. RT-qPCR was performed to measure the expression of MEG3 and LRRK2. ROC curve analysis was performed for diagnostic analysis. Cell transfections were performed to analyze the interaction between MEG3 and LRRK2. Cell apoptosis and MTT assays were performed to evaluate the effect of cell transfections on cell apoptosis and viability. RESULTS: MEG3 was downregulated in PD patients compared to that in the healthy controls. ROC curve analysis showed altered expression of MEG3 in PD patients. MEG3 was also down-regulated in SH-SY5Y cells treated with MPP + . Overexpression of MEG3 increased the expression levels of leucine-rich repeat kinase 2 (LRRK2) in SH-SY5Y cells. In contrast, overexpression of LRRK2 showed no significant effects on MEG3. Overexpression of MEG3 improved the viability and inhibited the apoptosis of SH-SY5Y cells pretreated with MPP + . CONCLUSIONS: In conclusion, lncRNA MEG3 is downregulated in PD and may affect the expression of LRRK2 to regulate cell viability and apoptosis involved in PD.

Effects of LncRNA MEG3 on immunity and autophagy of non-small cell lung carcinoma through IDO signaling pathway.

BACKGROUND: The study was done to investigate the effect of LncRNA MEG3 on the immunity and autophagy of non-small cell lung carcinoma through the IDO signaling pathway. METHODS: A total of 78 cases of early NSCLC patients (research group; RG) and 69 cases of health controls (control group; CG) during the same time were included. The contents of LncRNA MEG3 and miR-543 in peripheral blood and tissues and their diagnostic values for NSCLC were detected. The relationship between LncRNA MEG3 and miR-543 and their posttreatment contents and influence on the prognosis of NSCLC patients were tested. The expression of LncRNA MEG3, miR-543, and IDO (IDO1, IDO2, and TDO proteins) in the lung tissue of rats and the immune function in the CG and the RG were detected. The effects of LncRNA MEG3 and miR-543 on the biological behavior of NSCLC cells were determined. The role of LncRNA MEG3, miR-543, and IDO in NSCLC was verified. RESULTS: LncRNA MEG3 was low in peripheral blood and tissues, while miR-543 was high (P < 0.05); both had good diagnostic values for NSCLC (P < 0.05). LncRNA MEG3 had a negative correlation with miR-543 (P < 0.05) and influenced the prognosis of NSCLC patients (P < 0.05). LncRNA MEG3 in the lung tissue of rats using IDO inhibitor was elevated compared with that of lung carcinoma model rats (P < 0.05). The level of miR-543 was declined compared with that of lung carcinoma model rats (P < 0.05). The levels of IDO1, IDO2, and TDO proteins were evidently declined compared with those of lung carcinoma model rats (P < 0.05). Compared with lung carcinoma model rats, CD3+, CD4+, and CD4+/CD8+ of IDO inhibitor rats were elevated, while CD8+ was declined (P < 0.05). Cell proliferation and invasion ability and IDO1, IDO2, TDO, Beclin-1, and LC3-II proteins were declined in the sh-LncRNA MEG3 group (P < 0.05), while those in the mimics-miR-543 group were evidently elevated (P < 0.05). However, the double luciferase activity detection and RIP experiment confirmed that there was targeted regulation among them (P < 0.05). CONCLUSION: MEG3 has low expression in NSCLC and affects the immunity and autophagy of NSCLC cells via regulating the miR-543/IDO signaling pathway, which is effective for the treatment of NSCLC.

miR-665 promotes the progression of gastric adenocarcinoma via elevating FAK activation through targeting SOCS3 and is negatively regulated by lncRNA MEG3.

Studies have found that miR-665 acted as a tumor suppressor or an oncogene in different malignancies. miR-665 expression was elevated in gastric adenocarcinoma tissues; however, its role and mechanism in this disease are not fully clarified. The expression of miR-665 and its target gene was detected in human gastric adenocarcinoma tissues and cells. Moreover, we analyzed the effects of miR-665 on the proliferation, migration, and epithelial-mesenchymal transition (EMT) of gastric adenocarcinoma cells as well as tumor growth in vivo. The mechanisms of miR-665 in gastric adenocarcinoma were investigated by using molecular biology techniques. We found miR-665 was upregulated and suppressor of cytokine signaling 3 (SOCS3) was downregulated in gastric adenocarcinoma tissues and cells. Elevated miR-665 was positively correlated with tumor size, lymph node metastasis, invasion depth, TNM stage, and poor differentiation in gastric adenocarcinoma patients. Overexpression of miR-665 promoted, whereas knockdown of miR-665 suppressed the proliferation, migration, and EMT of gastric adenocarcinoma cells. Furthermore, we demonstrated that miR-665 functioned through targeting SOCS3, followed by activation of the FAK/Src signaling pathway in gastric adenocarcinoma cells. miR-665 antagomir inhibited tumor growth as well as the activation of the FAK/Src pathway but increased SOCS3 expression in nude mice. In addition, miR-665 expression was negatively regulated by long noncoding RNA maternally expressed gene 3 (MEG3). In conclusion, miR-665 acted as an oncogene in gastric adenocarcinoma by inhibiting SOCS3 followed by activation of the FAK/Src pathway and it was negatively modulated by MEG3. miR-665 may be a promising therapeutic target for the treatment of gastric adenocarcinoma.

LncRNA MEG3 suppressed the progression of ovarian cancer via sponging miR-30e-3p and regulating LAMA4 expression.

BACKGROUND: Ovarian cancer (OC) is a common female reproductive malignancy with a high mortality rate. Although LAMA4 was observed to be downregulated in OC cells, its mechanism in regulating OC metastasis is still unknown. This study aimed to investigate the effect of LAMA4 and its mechanism on OC. METHODS: To achieve this aim, a microarray analysis was performed to screen out the key genes involved in OC pathogenesis. Western-blot and qRT-PCR assays were also carried out to detect protein and mRNA expressions, respectively. A luciferase reporter assay was further used to confirm the direct interaction of miR-30e-3p with MEG3, and the direct interaction of miR-30e-3p with LAMA4 mRNA. Cytological experiments (CCK8, colony formation assay, wound-healing assay etc.) were then performed to explore the roles of miR-30e-3p, MEG3, and LAMA4 in OC cells. RESULTS: After carrying out microarray analysis, LAMA4 was confirmed as a key gene associated with OC pathogenesis. Research results proved that miR-30e-3p was markedly upregulated, while MEG3 and LAMA4 were noticeably downregulated in OC tissues and cells. The overexpression of LAMA4 significantly impaired the proliferation, migration, and invasion of OC cells. However, the upregulation of MEG3 increased the expression of LAMA4 by sponging miR-30e-3p, which alleviated the malignancy of OC cells. CONCLUSIONS: Observations showed that forced LAMA4 overexpression could inhibit OC progression, which was regulated by MEG3 via sponging miR-30e-3p. The findings of this research could provide new insights into the mechanism by which MEG3 and LAMA4 exert their anti-oncogenic roles in OC progression.Trial registration Not applicable.