X-inactive Specific Transcript Downregulation Research Articles

Downregulation of lncRNA XIST may promote Th17 differentiation through KDM6A-TSAd pathway in neuromyelitis optica spectrum disorders.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease with significant female preponderance. X inactive specific transcript (XIST) is a long non-coding RNA (lncRNA) and a key regulator of X-chromosome inactivation which is related to the sex-bias of autoimmunity. And Th17 cell proportion was significantly elevated in NMOSD according to our previous study. This study aimed to explore the expression levels of lncRNA XIST-KDM6A-TSAd pathway in lymphocytes of female NMOSD patients, and investigate its possible relationship with pathogenesis of NMOSD. The study enrolled 30 acute-phase untreated female NMOSD patients and 30 age-matched female healthy controls, their lymphocytes were collected for experiments. Microarray as well as validation experiments showed lncRNA XIST was significantly downregulated in the NMOSD group. And the levels of lysine demethylase 6A (KDM6A) decreased in NMOSD and showed significant positive correlation with XIST. The levels of T cell-specific adapter (TSAd) mRNA and protein levels were significantly lower in NMOSD. And Chromatin immunoprecipitation assay demonstrated that NMOSD had more H3K27me3 modification than control at TSAd promoter region. The present study introduced a potential pathway that following lncRNA XIST downregulation, which process may promote Th17 differentiation in NMOSD. These findings shed new light on the immune regulation mechanism about lncRNA XIST and related epigenetic features, which may contribute to develop female-specific treatment plans.

LncRNA XIST from the bone marrow mesenchymal stem cell derived exosome promotes osteosarcoma growth and metastasis through miR-655/ACLY signal

BackgroundLong non-coding RNA X-inactive specific transcript (XIST) regulates the progression of a variety of tumors, including osteosarcoma. Bone marrow mesenchymal stem cells (BMSCs) can be recruited into osteosarcoma tissue and affect the progression by secreting exosomes. However, whether BMSCs derived exosomes transmit XIST to regulate the growth and metastasis of osteosarcoma and the related mechanism are still unclear.MethodIn this study, BMSCs derived exosomes were used to treat human osteosarcoma cells MG63 and 143B, and the level of XIST in BMSCs was intervened by siRNA. CCK-8, EdU, transwell assays were used to analyze the changes of cell proliferation, migration and invasion. Bioinformatics analysis, RNA pulldown and dual-luciferase reporter gene assays validated the targeted relationship of XIST with miR-655 and the interaction between miR-655 and ACLY 3’-UTR. 143B/LUC cell line was used to establish an animal model of in situ osteosarcoma to verify the found effects of XIST on osteosarcoma. Oil Red O staining, Western blot and so on were used to detect the changes of lipid deposition and protein expression.ResultsIt was found that BMSCs derived exosomes promoted the proliferation, migration and invasion of osteosarcoma cells, and the down-regulation of XIST inhibited this effect. miR-655 mediated the role of BMSCs derived exosomal XIST in promoting the progression of osteosarcoma and down-regulation of miR-655 could reverse the effects of inhibiting XIST on the proliferation, migration and invasion of osteosarcoma cells. Meanwhile, animal level results confirmed that BMSCs derived exosomal XIST could promote osteosarcoma growth and lung metastasis by combining with miR-655. In-depth mechanism study showed that BMSCs derived exosomal XIST combined with miR-655 to increase the protein level of ACLY, which led to lipid deposition and activate β-catenin signal to promote the proliferation, migration and invasion of osteosarcoma cells.ConclusionThis study showed that BMSCs derived exosomal XIST could enter osteosarcoma cells, bind and down-regulates the level of miR-655, resulting in an increase in the level of ACLY, thus increasing the lipid deposition and the activity of β-catenin signal to promote the growth and metastasis of osteosarcoma.

XIST promotes apoptosis and the inflammatory response in CSE-stimulated cells via the miR-200c-3p/EGR3 axis

BackgroundChronic obstructive pulmonary disease (COPD) is a disease that causes obstructed airways and abnormal inflammatory responses in the lungs. Early growth response 3 (EGR3) has been revealed to play a vital role in the regulation of the inflammatory response in certain diseases. We aimed to explore the role of EGR3 and its upstream mechanism in COPD.Methods and resultIn the present study, 16HBE cells were treated with cigarette smoke extract (CSE) to mimic the inflammatory response in vitro. RT-qPCR revealed that the expression of EGR3 was upregulated in lungs from COPD patients. EGR3 expression in 16HBE cells was increased by CSE treatment. Moreover, flow cytometry analysis and western blot analysis showed that EGR3 downregulation inhibited 16HBE cell apoptosis. EGR3 silencing decreased the protein levels of IL-6, TNF-α, IL-1β and COX2 in CSE-stimulated 16HBE cells. In addition, EGR3 was targeted by microRNA-200c-3p (miR-200c-3p) in 16HBE cells. MiR-200c-3p expression was significantly decreased in lung tissues from COPD patients compared to that in healthy controls. Furthermore, miR-200c-3p bound to lncRNA X-inactive specific transcript (XIST) in 16HBE cells. Additionally, XIST expression was elevated in lung tissues from COPD patients. Rescue assays indicated that EGR3 overexpression counteracted the effects of XIST downregulation on apoptosis and inflammation in CSE-stimulated 16HBE cells.ConclusionThe XIST/miR-200c-3p/EGR3 axis facilitated apoptosis and inflammation in CSE-stimulated 16HBE cells. These findings may provide novel insight for treating COPD by alleviating lung inflammation.

Down-regulation of long non-coding RNA XIST aggravates sepsis-induced lung injury by regulating miR-16-5p.

This study aims to explain the role and related mechanisms of long non-coding RNA (lncRNA) X inactive specific transcript (XIST) in sepsis-induced acute lung injury (ALI). The in vivo septic models and in vitro septic model were established. In animal models, the lung injury of the rats was evaluated after XIST was overexpressed. In cell models, the effects of XIST and microRNA (miR)-16-5p on ALI was detected by MTT assay, Western blot and ELISA. The interaction between XIST and miR-16-5p was investigated by bioinformatics analysis, dual-luciferase reporter assay, RIP assay and RNA pull-down assay. We found that XIST expression was down-regulated in lung tissues of septic rats and lipopolysaccharide-stimulated cells, while the expression of miR-16-5p was up-regulated. Down-regulation of XIST significantly promoted pulmonary edema, increased the levels of TNF-α, IL-1β and malondialdehyde, inhibited the cell viability and decreased the level of superoxide dismutase. Mechanistically, it was confirmed that XIST could sponge miR-16-5p, and thus repress its expression, and the transfection of miR-16-5p mimics could reverse the effects of XIST over-expression in the cell model. Collectively, it is concluded that XIST reduces sepsis-induced ALI via regulating miR-16-5p.

Long Non-Coding RNA XIST Promotes Wilms Tumor Progression Through the miR-194-5p/YAP Axis.

PurposeAlthough the long non-coding RNA (lncRNA) X inactive-specific transcript (XIST) has been reported to have an anti-tumor effect in multiple malignant tumors, its role in Wilms tumor (WT) progression has not been characterized. Thus, we investigated the underlying mechanism by which XIST regulates WT progression.Patients and MethodsWe performed microarray analysis and real-time quantitative PCR (RT-qPCR) to detect the expression levels of XIST lncRNA, microRNA-194-5p (miR-194-5p), and YAP (yes-associated protein in Hippo pathway) in tumor and matched adjacent normal tissues and blood collected from 49 WT patients. We also conducted bioinformatics analyses to identify differentially expressed genes. We measured the effects of XIST overexpression and knockdown on cell proliferation, apoptosis, migration, and invasion, and its association with the miR-194-5p/YAP pathway in the rhabdoid G401cell line using flow cytometry, transwell assays, immunohistochemistry, Western blot analysis, and the dual luciferase reporter gene assay.ResultsWe found that XIST lncRNA levels were increased in blood and tissue samples of WT patients, and this upregulation was significantly correlated with TNM staging and shorter survival time. Notably, we found that XIST upregulation correlated with miR-194-5p downregulation and YAP upregulation in WT tissues, suggesting that XIST regulates the miR-194-5p/YAP pathway. Conversely, XIST downregulation inhibited WT cell proliferation, migration, and invasion and induced apoptosis. Our study revealed the oncogenic role of the lncRNA XIST in WT and demonstrated its role as a competitive endogenous RNA that regulates the miR-194-5p/YAP pathway.ConclusionOur study demonstrates XIST’s potential as a clinical prognostic biomarker and therapeutic target for WT.

LncRNA XIST regulates atherosclerosis progression in ox-LDL-induced HUVECs.

Long noncoding RNAs (lncRNAs) have been verified as vital regulators in human disease, including atherosclerosis. However, the precise role of X-inactive-specific transcript (XIST) in atherosclerosis remains unclear. The proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs) exposed to low-density lipoprotein (ox-LDL) were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazol-3-ium bromide, and flow cytometry assays, correspondingly. The western blot assay was used to quantify protein expression. Lactate dehydrogenase activity and the concentrations of inflammatory factors were measured by matched kits. The real-time quantitative polymerase chain reaction (qPCR) was used to determine α-smooth muscle actin, smooth muscle protein 22-α, XIST, miR-98-5p, and pregnancy-associated plasma protein A (PAPPA) levels in HUVECs. The relationship among XIST, miR-98-5p, and PAPPA was analyzed by dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays. We found ox-LDL repressed proliferation and induced inflammation and apoptosis in HUVECs. Loss-of-functional experiment suggested that the downregulation of XIST overturned the ox-LDL-induced effects on HUVECs. Additionally, overexpression of miR-98-5p-induced effects on ox-LDL-stimulated HUVECs was abolished by upregulation of XIST. However, silencing of miR-98-5p strengthened the ox-LDL-induced effects on HUVECs by increasing expression of PAPPA. Mechanistically, XIST could regulate PAPPA expression in ox-LDL-induced HUVECs by sponging miR-98-5p, providing understanding for atherosclerosis.

Silencing long non-coding RNA XIST suppresses drug resistance in acute myeloid leukemia through down-regulation of MYC by elevating microRNA-29a expression

BackgroundLong non-coding RNAs (lncRNAs) are biomarkers participating in multiple disease development including acute myeloid leukemia (AML). Here, we investigated molecular mechanism of X Inactive-Specific Transcript (XIST) in regulating cellular viability, apoptosis and drug resistance in AML.MethodsXIST, miR-29a and myelocytomatosis oncogene (MYC) expression in AML bone marrow cells collected from 62 patients was evaluated by RT-qPCR and Western blot analysis. Besides, the relationship among XIST, miR-29a and MYC was analyzed by dual luciferase reporter assay, RIP, and RNA pull down assays. AML KG-1 cells were treated with anti-tumor drug Adriamycin. The role of XIST/miR-29a/MYC in cellular viability, apoptosis and drug resistance in AML was accessed via gain- and loss-of-function approaches. At last, we evaluated role of XIST/miR-29a/MYC on tumorigenesis in vivo.ResultsXIST and MYC were up-regulated, and miR-29a was down-regulated in AML bone marrow cells. Silencing XIST inhibited cellular activity and drug resistance but promoted cellular apoptosis of KG-1 cells by down-regulating MYC. XIST inhibited miR-29a expression to up-regulate MYC. Moreover, silencing XIST inhibited tumorigenesis of AML cells in vivo.ConclusionsOverall, down-regulation of XIST decreased MYC expression through releasing the inhibition on miR-29a, thereby reducing drug resistance, inhibiting viability and promoting apoptosis of AML cells.

Downregulation of lncRNA XIST Represses Tumor Growth and Boosts Radiosensitivity of Neuroblastoma via Modulation of the miR-375/L1CAM Axis

Neuroblastoma (NB) is a heterogeneous tumor that is common in infants and young children. Long non-coding RNA X-inactive specific transcript (XIST) is implicated in NB advancement. Nevertheless, the role and regulatory mechanism by which XIST in NB are not fully elucidated. Expression levels of XIST, microRNA-375-5p (miR-375), and L1 cell adhesion molecular (L1CAM) were examined through quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, proliferation, and colony formation of NB cells were determined with flow cytometry, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), or cell colony formation assays. Cell apoptotic rate was detected with flow cytometry assay. The relationship between XIST or L1CAM and miR-375 was verified via dual-luciferase reporter assay. The level of L1CAM protein was examined through western blotting. The role of XIST in vivo was confirmed through xenograft assay. XIST and L1CAM were upregulated while miR-375 was downregulated in NB tissues and cells. XIST depletion repressed tumor growth in vivo and elevated radiosensitivity, arrested cell cycle progression, and impeded proliferation of NB cells in vitro. Mechanistically, XIST modulated L1CAM expression through competitively binding to miR-375. Furthermore, miR-375 inhibitor recovered XIST inhibition-mediated effects on the radiosensitivity and malignant behaviors of NB cells. Also, L1CAM overexpression reversed the effects of miR-375 enhancement on the cell cycle progression, proliferation, and radiosensitivity of NB cells. XIST downregulation repressed tumor growth and boosted radiosensitivity of NB via modulating the miR-375/L1CAM axis, indicating that XIST was a promising target for NB treatment.

Long noncoding RNA XIST knockdown suppresses the growth of colorectal cancer cells via regulating microRNA-338-3p/PAX5 axis.

Colorectal cancer is one of the most common human cancers worldwide. Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have been reported as the regulators in cancers. The purpose of this study was to reveal the functional mechanisms of lncRNA x inactive specific transcript (XIST) and miR-338-3p in colorectal cancer cells. The transcription level and protein level of genes were assessed by quantitative real-time PCR (qRT-PCR) and western blot assay, respectively. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry analysis were used to determine cell proliferation ability and apoptosis rate, respectively. In addition, cell migratory ability and invasive ability were measured using transwell assay. Besides, the interaction between miR-338-3p and XIST or paired box 5 (PAX5) was predicted by starBase or TargetScan and then verified by the dual-luciferase reporter assay. XIST and PAX5 expression were increased, and miR-338-3p expression was decreased in colorectal cancer tissues and cells. XIST knockdown significantly repressed cell proliferation, migration and invasion, and accelerated apoptosis in colorectal cancer cells. Interestingly, XIST directly downregulated miR-338-3p expression to increase PAX5 level. As expected, XIST knockdown inhibited colorectal cancer cell growth by modulating miR-338-3p expression. Furthermore, miR-338-3p suppressed cell growth via downregulation of PAX5 level in colorectal cancer cells. Our results demonstrated that the downregulation of XIST inhibited cell proliferation, migration and invasion, and induced apoptosis through modulating miR-338-3p/PAX5 axis in colorectal cancer cells, providing potential target for the prevention and treatment of colorectal cancer.

Long non-coding RNA XIST contributes to osteoarthritis progression via miR-149-5p/DNMT3A axis

Long non-coding RNAs (lncRNAs) are largely involved in the development of osteoarthritis (OA), a chronic and degenerative joint disease. The objective of this paper is to research the functional role and molecular mechanism of lncRNA X inactive specific transcript (XIST) in OA. The levels of XIST, microRNA-149-5p (miR-149-5p), and DNA methyltransferase 3A (DNMT3A) were measured. Cell viability and apoptosis rate were determined. Associated protein levels were examined through Western blot. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were implemented for confirming the target relation. And the role of XIST on OA in vivo was investigated by a rat model. XIST was expressed at a high level in OA cartilage tissues and IL-1β-treated chondrocytes. XIST knockdown promoted cell viability but restrained cell apoptosis and extracellular matrix (ECM) protein degradation in IL-1β-treated chondrocytes. XIST directly targeted miR-149-5p and miR-149-5p down-regulation restored si-XIST-mediated pro-proliferative and anti-apoptotic or ECM degradative effects. DNMT3A was a target gene of miR-149-5p and DNMT3A overexpression ameliorated miR-149-5p-induced promotion of cell viability but repression of apoptosis and ECM degradation. Knockdown of XIST reduced DNMT3A level by motivating miR-149-5p expression. The inhibitory influence of XIST down-regulation on OA evolvement was also achieved by miR-149-5p/DNMT3A axis in vivo. In a word, knockdown of XIST can repress the development of OA by miR-149-5p/DNMT3A axis. This study discovers the XIST/miR-149-5p/DNMT3A axis in regulating OA evolution, which is beneficial for understanding the molecular pathomechanism and can lay a good foundation for targeted therapy of OA treatment.

Long non-coding RNA XIST expedites lung adenocarcinoma progression through upregulating MDM2 expression via binding to miR-363-3p.

BackgroundLung adenocarcinoma (LAD) is a highly aggressive malignant tumor which threatens the health and life of the population. Long non‐coding RNA X‐inactive specific transcript (XIST) and mouse double minute clone 2 (MDM2) are connected with the tumorigenesis of LAD. Nevertheless, whether MDM2 is regulated by XIST has not previously been reported in LAD.MethodsQuantitative real‐time polymerase chain reaction (qRT‐PCR) was employed to detect the expression of XIST, microRNA‐363‐3p (miR‐363‐3p) and MDM2 in LAD tissues and cells. The proliferation, migration, invasion and apoptosis of LAD cells were determined by 3‐(4, 5‐dimethylthiazol‐2‐YI)‐2, 5‐diphenyltetrazolium bromide (MTT), transwell or flow cytometry assay, respectively. MDM2 protein level was detected using western blot analysis. Dual‐luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pulldown assay were performed to determine the interaction among XIST, miR‐363‐3p and MDM2. A xenograft tumor model was constructed to validate the effect of XIST on LAD cells in vivo.ResultsWe found that XIST and MDM2 were remarkably elevated while miR‐363‐3p was reduced in LAD tissues and cells. Both XIST and MDM2 downregulation restrained proliferation, migration and invasion, and facilitated apoptosis of LAD cells in vitro. Importantly, XIST bound to miR‐363‐3p to modulate MDM2 expression in LAD cells. Moreover, miR‐363‐3p knockdown or MDM2 elevation reversed the effects of XIST downregulation on the proliferation, migration, invasion and apoptosis of LAD cells. Furthermore, XIST knockdown constrained tumor growth on LAD cells in vivo.ConclusionsXIST knockdown repressed proliferation, migration and invasion, and accelerated apoptosis of LAD cells by downregulating MDM2 expression via binding to miR‐363‐3p.Key pointsSignificant findings of the studyXIST and MDM2 were abnormally enhanced in LAD tissues and cells.Both downregulation of XIST and MDM2 repressed proliferation, migration and invasion, and boosted apoptosis of LAD cells in vitro.XIST bound to miR‐363‐3p to regulate MDM2 expression in LAD cells.Downregulation of XIST impeded tumor growth on LAD cells in vivo.What this study addsThis study confirmed that XIST was a potential target for inhibiting the development of LAD, and affords a possible strategy for the treatment of LAD in the future.

LncRNA XIST facilitates cell growth, migration and invasion via modulating H3 histone methylation of DKK1 in neuroblastoma

ABSTRACT Long non-coding RNAs (lncRNAs) have been confirmed to be aberrantly expressed and involved in the progression of neuroblastoma. This study aimed to explore the expression profile of lncRNA X-inactive specific transcript (XIST) and its functional involvement in neuroblastoma. In this study, the relative level of XIST in neuroblastoma tissues and cell lines was detected by qPCR, and DKK1 protein expression was determined using western blot. The effect of XIST on cell growth, invasion and migration in vitro and in tumorigenesis of neuroblastoma was assessed. The level of H3K27me3 in DKK1 promoter was analyzed with ChIP-qPCR. Interaction between XIST and EZH2 was verified by RNA immunoprecipitation (RIP) and RNA pull-down assay. XIST was significantly upregulated in neuroblastoma tissues (n = 30) and cells lines, and it was statistically associated with the age and International Neuroblastoma Staging System (INSS) staging in neuroblastoma patients. Downregulation of XIST suppressed the growth, migration and invasion of neuroblastoma cells. EZH2 inhibited DKK1 expression through inducing H3 histone methylation in its promoter. XIST increased the level of H3K27me3 in DKK1 promoter via interacting with EZH2. Downregulation of XIST increased DKK1 expression to suppress neuroblastoma cell growth, invasion, and migration, which markedly restrained the tumor progression. In conclusion, XIST downregulated DKK1 by inducing H3 histone methylation via EZH2, thereby facilitating the growth, migration and invasion of neuroblastoma cells and retarding tumor progression.

Long non-coding RNA XIST promotes extracellular matrix degradation by functioning as a competing endogenous RNA of miR-1277-5p in osteoarthritis.

Osteoarthritis (OA) is a common and troublesome disease among the elderly, and is characterized by extracellular matrix (ECM) degradation. The function of the long non-coding RNA X-inactive-specific transcript (XIST) and its working mechanism in ECM degradation remains unclear. In the present study, XIST was revealed to be upregulated in OA specimens and in articular chondrocytes (ACs) derived from OA tissue (AC/OA) and interleukin-1β (IL-1β)-treated ACs. Loss-of-function experiments demonstrated that downregulation of XIST suppressed the degradation of the ECM in AC/OA and AC/IL-1β-5.0 cells. Furthermore, XIST, matrix metalloproteinase 13 (MMP-13) and ADAM metallopeptidase with thrombospondin type 1 motif 5 (ADAMTS5) were identified as targets of microRNA (miR)-1277-5p, and the reciprocal inhibitive effect between XIST and miR-1277-5p was elucidated. Furthermore, the role of XIST in ECM degradation was confirmed to be functioning as a competing endogenous RNA (ceRNA) of miR-1277-5p. Finally, the protective effect of the downregulation of XIST on ECM degradation was verified in an OA rat model. In conclusion, the present study suggests that XIST promotes MMP-13 and ADAMTS5 expression, indicating ECM degradation, by functioning as a ceRNA of miR-1277-5p in OA. The present study proposed a novel potential target with a new working mechanism in molecular treating of OA.

Long non-coding RNA XIST modulates cisplatin resistance by altering PDCD4 and Fas-Lexpressions in human nasopharyngeal carcinoma HNE1 cells in vitro

To explore the role of long non-coding RNA (lncRNA) X inactive specific transcript (XIST) in modulating cisplatin (DDP) resistance of human nasopharyngeal carcinoma cells and investigate the possible mechanism. Realtime PCR was performed to detect the expression of XIST in cisplatin-resistant human nasopharyngeal carcinoma cell line HNE1/DDP. The effects of up-regulation and down-regulation of XIST on DDP resistance, proliferation and apoptosis of HNE1/ DDP cells were assessed using MTT assay, EdU assay and flow cytometry. Western blotting was used to detect the changes in the expressions of programmed cell death 4 (PDCD4) and Fas ligand (Fas-L) proteins in the cells in response to up-regulation or down-regulation of XIST. The expression of XIST was significantly up-regulated in HNE1/DDP cells in comparison with HNE1 cells (0.57±0.06 vs 0.1±0.02, P < 0.05). Down-regulation of XIST significantly decreased while up-regulation of XIST obviously increased DDP resistance of HNE1/DDP cells (P < 0.05). Down-regulation of XIST significantly reduced the proliferation (6.17 ± 1.93 vs 16.59 ± 4.86, P < 0.05) and enhanced apoptosis [(18.04 ± 4.72)% vs (4.22 ± 1.65)%, P < 0.05], while upregulating XIST enhanced the proliferation (25.40±7.21 vs 13.16±3.95, P < 0.05) and inhibited apoptosis [(2.82±0.88)% vs (6.46± 1.75)%, P < 0.05] in HNE1/DDP cells. Down-regulation of XIST significantly increased the protein expressions of PDCD4 and Fas-L (P < 0.05) in HNE1/DDP cells, and up-regulation of XIST resulted in reverse changes in PDCD4 and Fas-L expressions (P < 0.05). XIST is up-regulated in HNE1/DDP cells, and down-regulation and up-regulation of XIST expression reduce and increase DDP resistance of the cells, respectively, possibly as a result of changes in the expressions of PDCD4 and Fas-L.

Down-regulation of the long non-coding RNA XIST ameliorates podocyte apoptosis in membranous nephropathy via the miR-217-TLR4 pathway.

What is the central question of this study? What is the role of the long non-coding RNA X-inactive specific transcript (XIST), which is up-regulated in injured podocytes and membranous nephropathy, in the pathogenesis of membranous nephropathy? What is the main finding and its importance? XIST was up-regulated in kidney tissue with membranous nephropathy and in injured podocytes. Down-regulation of XIST inhibited podocyte apoptosis. XIST negatively regulated miR-217, and miR-217 modulated Toll-like receptor 4. Inhibition of XIST suppressed podocyte apoptosis induced by angiotensin II via miR-217. Membranous nephropathy is often characterized by glomerular podocyte injury. Up-regulation of the long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) has been verified in membranous nephropathy and in injured podocytes. Here the role of XIST in podocyte injury and membranous nephropathy was explored. Quantitative real-time PCR and western blot were performed to detect the expression of XIST and miR-217, and Toll-like receptor 4 (TLR4) protein, respectively. Podocyte apoptosis was evaluated with flow cytometry. Interaction between XIST and miR-217 was analysed by RNA immunoprecipitation and RNA pull-down assay. A dual luciferase reporter assay was used to examine the interplay between miR-217 and TLR4. Up-regulation of the lncRNA XIST and angiotensin II (Ang II) and kidney and podocyte injury were indicated in kidney tissue of patients with membranous nephropathy. Increase of XIST and apoptosis were induced by Ang II in podocytes. Down-regulation of XIST reversed podocyte apoptosis induced by Ang II. MiR-217 was negatively regulated by XIST. MiR-217 controlled TLR4 by targeting its 3'-untranslated region. XIST modulated TLR4 through miR-217 and inhibition of XIST reduced podocyte apoptosis induced by Ang II via regulating miR-217. Down-regulation of XIST ameliorates podocyte apoptosis via the miR-217-TLR4 pathway, which may improve membranous nephropathy.

Long non-coding RNA XIST serves an oncogenic role in osteosarcoma by sponging miR-137.

The long non-coding RNA X inactive-specific transcript (XIST) has been implicated in certain human cancers, including osteosarcoma (OS), but the molecular mechanism of XIST underlying OS progression remains to be fully uncovered. In the present study, reverse transcription-quantitative polymerase chain reaction data demonstrated that XIST was significantly upregulated in OS tissues and cell lines (Saos-2, U2OS, HOS and MG63) compared with adjacent non-tumour tissues and normal human osteoblast cell line HFOB1.19. Bioinformatics analysis and luciferase reporter gene assay data demonstrated that XIST could directly target microRNA (miR)-137 and negatively regulate the expression of miR-137 in Saos-2 and U2OS cells. Furthermore, miR-137 was markedly downregulated in OS tissues and cell lines. An inverse association between XIST and miR-137 expression was observed in OS tissues. Knockdown of XIST caused a significant reduction in cell proliferation and invasion and suppressed matrix metalloproteinase (MMP2) and MMP9 protein levels in Saos-2 and U2OS cells. Furthermore, inhibition of miR-137 expression abolished the effects of XIST downregulation on the proliferation and invasion of OS cells. In summary, the present study suggests that XIST promotes OS cell proliferation and invasion by inhibition of miR-137 expression. Thus, XIST may be a potential therapeutic target for the treatment of OS.

LncRNA XIST promotes the epithelial to mesenchymal transition of retinoblastoma via sponging miR-101

Accumulating evidence demonstrated that abnormal expression of long non-coding RNAs (lncRNAs) was closely associated with cancer development including retinoblastoma (RB). LncRNA X inactive specific transcript (XIST) has been found to function as an oncogene or a tumor suppressor in several cancers. However, the role and underlying mechanism of XIST in RB have not been clarified. The expression of XIST, microRNA (miR)− 101, zinc finger E-box binding homeobox (ZEB) 1, and ZEB2 was detected in human RB tissues and cell lines. The effects of XIST on the proliferation, migration, invasion, epithelial to mesenchymal transition (EMT), and apoptosis of RB cells were evaluated after downregulation of XIST. Furthermore, the mechanism of XIST was mainly focused on miR-101/ZEB1 or ZEB2 signaling. We found the expression of XIST, ZEB1 and ZEB2 was increased, whereas miR-101 was reduced in RB tissues and cells. Knockdown of XIST significantly suppressed the proliferation, migration, invasion and EMT, but promoted the apoptosis and caspase-3 activity. Moreover, we found that XIST functioned as a competing endogenous RNA (ceRNA) for miR-101 to regulate the de-repression of its endogenous targets ZEB1 and ZEB2. In conclusion, these findings suggest that XIST may facilitate the progression of RB through acting as a ceRNA for miR-101 to mediate the expression of ZEB1 and ZEB2. This may provide novel therapeutic options for RB.