MALAT1 Expression Research Articles

The Long Non-Coding RNA MALAT1 Is Necessary for Hematopoietic Stem and Progenitor Cell Expansion and Preleukemic Myeloproliferation in TET2 Deficient Myeloid Neoplasms

Ten Eleven Translocation 2 (TET2) is a dioxygenase which regulates gene expression by oxidizing 5-methylcytosine to 5-hydroxymethylcytosine. Loss of function mutations in TET2 occur in up to 58% and 30% of myeloid malignancies and clonal hematopoiesis respectively. Loss of TET2 function also occurs with isocitrate dehydrogenase 2 (IDH2) mutations in Acute Myeloid Leukemia (AML) via 2-hydroxyglutarate (2-HG). Genetically engineered murine models (GEMM) of Tet2 deficiency produce a Chronic Myelomonocytic Leukemia (CMML)-like phenotype with splenomegaly, granulomonocytic expansion and increased bone marrow hematopoietic stem and progenitors (LSK). Further, bone marrow mononuclear cell (BMNC) transplant models of Tet2-/- clonal hematopoiesis suggest that this myeloid expansion leads to enhanced inflammation and increased cardiovascular disease risk. However, the downstream effects of TET2 loss of function leading to this phenotype are unknown. Here we show that TET2-deficient granulomonocytic expansion and inflammation are mediated via MALAT1, a long non-coding RNA overexpressed in several malignancies. MALAT1 expression was increased in BMNCs from IDH2 mutated AML patients (n=152 WT n=17 mutant IDH2, p=0.04). Increased MALAT1 expression was also seen in human and murine models of TET2 deficiency including isogenic IDH2 mutated TF-1 cells (5 biological replicates p=0.005), 2-HG treated leukemia cell lines (2 biological replicates p<0.0001) and BMNCs from Tet2f/f mice (n= 7/grp p=0.005). To evaluate the impact of Malat1 on normal and Tet2 deficient hematopoiesis we utilized the Malat1tg overexpression and Tet2-/-Malat1-/-GEMM models. Similar to Tet2-/- mice, bone marrow (n=4/grp p=0.02) and spleen (n=8/grp p=0.004) LSK numbers were increased in Malat1tg mice compared to control. However, unlike Tet2-/-LSKs, MALAT1tgLSKs did not show increased self-renewal in serial in vivo competitive transplants. Further, depleting Malat1 in Tet2-/- mice did not rescue the increased self-renewal capacity seen in Tet2-/- LSKs. Collectively, these data suggest that Malat1 overexpression is sufficient for LSK expansion but does not impact LSK function. Splenomegaly, myeloproliferation and extramedullary hematopoiesis is a phenotype termed Preleukemic Myeloproliferation (PMP) and is predictive of myeloid neoplasm development in Tet2-/- models (Meisel M et al, Nature 2018). Consistent with a role of Malat1 in PMP (Fig A), Malat1 overexpression recapitulated PMP at 8 (n=10/grp p<0.0001) and 20 (n=10/grp p=0.0005) weeks. Malat1 overexpression was also associated with an increase in classical monocytes in the peripheral blood- a hallmark of CMML (8 weeks n= 7/grp p<0.0001, 20 weeks n=10/grp p=0.0007). This was recapitulated in Tet2-/-mice (n=3/grp p=0.001) and CMML patients with TET2 mutations (n=27 mutant TET2 v 109 WT, odds ratio 5.6 p= 0.001). Finally, depleting Malat1 in a Tet2-deficient GEMM rescued PMP (n=4 Tet2-/-Malat1-/-v 5 Tet2-/-p=0.01) and classical monocytosis (n=2/grp p=0.002) suggesting that Malat1 overexpression is both sufficient and necessary for PMP in Tet2 deficient leukemia. This impact was also observed in recipients in BMNC competitive transplant experiments (Fig B). Initial insights into the molecular mechanism underlying the role of Malat1 in PMP were derived from analyzing competitor and host cells during in vivo competitive transplants. Interestingly, transplant recipients with Malat1tg LSK demonstrated myeloid and granulomonocytic expansion in both donor and non-donor cells suggesting that the effects of Malat1 overexpression are, in part, cell extrinsic. Consistent with this hypothesis and the impact of NF-kB on inflammatory cytokine secretion and Tet2-/- PMP, we show that MALAT1 deletion in human leukemia attenuates NF-kB activity by enhancing the phosphatase activity of PP2A. Further, Interleukin 6 (IL-6), a major downstream target of NF-kB and potent activator of myelopoiesis in response to inflammatory stimuli, was increased in the plasma of MALAT1tg mice (n=8/grp p=0.01) suggesting a possible cell-extrinsic mechanism for Malat1 dependent PMP. Ongoing studies are focused on demonstrating that IL-6 is necessary for Malat1 dependent PMP. Our current data provides hitherto unknown insights establishing MALAT1 as a major effector of TET2 loss of function which may lead to novel therapeutic options in TET2 deficient myeloid neoplasms. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Unraveling the Heterogeneity of Multiple Myeloma Cells By Single-Cell RNA Sequencing Analysis

Multiple myeloma (MM) is a malignancy of clonal plasma cells with identical variable-diversity-joining (VDJ) region recombination of immunoglobulin loci (called repertoire) and extensive genome or transcriptome heterogeneity. Even though many new treatment modalities have been developed and the prognosis of patients has improved significantly, most cases of MM remain incurable. Recent evidence suggests that non-genetic cell plasticity and changes in cell state underlie the therapy resistance and tumor relapse, but the mechanisms remain largely unknown. Here, we have attempted to understand comprehensive architecture of the entire tumor cell populations using repertoire clonality as fingerprint. First, we subdivided bone marrow samples of primary MM at different stages (n=8) into 11 fractions based on the known surface antigens of MM and performed bulk RNA sequencing (bulk RNA-seq). Analysis of the repertoire revealed that tumor cells were also present in some minor fractions other than the main fraction (Lin-/CD19-/CD38++/CD138+) as the stage progressed. Importantly, cells with clonal repertoire were detected in CD138 negative fraction (Lin-/CD19-/CD38++/CD138-) in most samples (Monoclonal gammopathy of undetermined significance (MGUS) / Smoldering multiple myeloma (SMM) = 4.15±2.28%, Primary MM = 6.78±3.59%, Relapse MM = 7.8±5.82% [mean±95%Cl], n=24). The CD138 positive and negative cells were also morphologically different, suggesting that they were composed by cells of distinct characteristics. Indeed, comparison of the transcriptome data revealed 296 differentially expressed genes (DEGs) between these fractions (250 up-regulated and 46 down-regulated in CD138 negative fractions). Of interest, several pathways related to H3K4 methylation were positively enriched in CD138 negative fraction (p <0.001), which included KMT2A, KMT2B, KMT2C, KMT2D, and ASH1L, suggesting that differential methylation of histone H4 accounts for the heterogeneity of MM. In order to achieve a high-resolution and comprehensive evaluation of the entire tumor cell populations, we performed single-cell RNA sequencing (scRNA-seq) and single-cell VDJ targeted sequencing (scVDJ-seq) concurrently on Lin-/CD38++ sorted cells of 8 bone marrow samples from 7 patients including pre- and post-treatment status samples. This method allowed us to define normal cells and MM cells at the single-cell level by clonal repertoire sequence independent of transcriptome characteristics. We divided 18,031 MM cells into 23 clusters after integration. We first defined CD138 positive and negative MM gene signature using bulk RNA-seq data and then evaluated the scRNA-seq data. Notably, the CD138 axis appeared to clearly subdivide main MM populations into those with CD138 positive and negative MM gene signature. We also found that a part of clusters, which showed CD138 negative MM gene signature, tended to remain at high proportions after treatment. These populations were characterized by low expression levels of MHC class-I components and TNFRSF17/BCMA as well as high expression of MCL1, MALAT1 and NEAT1, which have been previously implicated in treatment resistance, and were present in all samples. H3K4 methylation related genes were also up-regulated in these populations. Furthermore, we found several clusters with unique and interesting characteristics independent of the CD138 axis. Trajectory and velocity analysis suggested that all cell populations transit to each other. Taken together, our results establish the heterogeneity of MM cells by the CD138 axis, which may be characterized by epigenetic plasticity. They also highlight CD138 negative population as a potential cause of treatment resistance and relapse. By using information of repertoire, we have achieved a comprehensive and accurate single-cell analysis of MM cell diversity that was not limited by cell surface antigens or transcriptome characteristics. We are currently analyzing near minimal residual disease (MRD) level samples using the same scRNA-seq methods and the functional and epigenetic properties of CD138 positive and negative MM cells.

Mechanistic studies of MALAT1 in respiratory diseases.

Background: The incidence of respiratory diseases and the respiratory disease mortality rate have increased in recent years. Recent studies have shown that long non-coding RNA (lncRNA) MALAT1 is involved in various respiratory diseases. In vascular endothelial and cancer cells, MALAT1 expression triggers various changes such as proinflammatory cytokine expression, cancer cell proliferation and metastasis, and increased endothelial cell permeability. Methods: In this review, we performed a relative concentration index (RCI) analysis of the lncRNA database to assess differences in MALAT1 expression in different cell lines and at different locations in the same cell, and summarize the molecular mechanisms of MALAT1 in the pathophysiology of respiratory diseases and its potential therapeutic application in these conditions. Results: MALAT1 plays an important regulatory role in lncRNA with a wide range of effects in respiratory diseases. The available evidence shows that MALAT1 plays an important role in the regulation of multiple respiratory diseases. Conclusion: MALAT1 is an important regulatory biomarker for respiratory disease. Targeting the regulation MALAT1 could have important applications for the future treatment of respiratory diseases.

Effect of metformin on the long non-coding RNA expression levels in type 2 diabetes: an in vitro and clinical trial study.

It has been suggested that the anti-hyperglycemic effect of metformin could be associated with its impact on long non-coding RNA (lncRNA) expression levels. Accordingly, in the current study, we evaluated the effect of metformin on the expression of H19, MEG3, MALAT1, and GAS5 in in vitro and in vivo situations. The effect of hyperglycemia and metformin treatment on the lncRNAs expression level was evaluated in HepG2 cells. A total of 179 age- and sex-matched subjects, including 88 newly diagnosed patients with type 2 diabetes (T2D) and 91 healthy volunteers, were included in the case-control phase of the study. Moreover, 40 newly diagnosed patients participated in the study's open-labeled non-controlled clinical trial phase. The expression levels of lncRNA in HepG2 cells and whole blood samples were determined using QRT-PCR. In vitro results showed that hyperglycemia induced H19 and MALAT1 and decreased GAS5 expression levels. Moreover, metformin decreased H19 and increased GAS5 expression in high glucose-treated cells. Case-control study findings revealed that the circulating levels of H19, MALAT1, and MEG3 were significantlyelevated in T2D patients compared to the control subjects. Finally, results showed that the level of circulating H19 levels decreased while GAS5 increased in T2D patients after taking metformin for 2months. The results of the current study provided evidence that metformin could exert its effect in the treatment of T2D by altering the expression levels of H19 and GAS5.

COPA A-to-I RNA editing hijacks endoplasmic reticulum stress to promote metastasis in colorectal cancer

RNA editing is among the most common RNA level modifications for generating amino acid changes. We identified a COPA A-to-I RNA editing event in CRC metastasis. Our results showed that the COPA A-to-I RNA editing rate was significantly increased in metastatic CRC tissues and was closely associated with aggressive tumors in the T and N stages. The COPA I164V protein damaged the Golgi–ER reverse transport function, induced ER stress, promoted the translocation of the transcription factors ATF6, XBP1 and ATF4 into the nucleus, and activated the expression of MALAT1, MET, ZEB1, and lead to CRC cell invasion and metastasis. Moreover, the COPA A-to-I RNA editing rate was positively correlated with the immune infiltration score. Collectively, the COPA I164V protein hijacked ER stress to promote the metastasis of CRC, and the COPA A-to-I RNA editing rate may be a potential predictor for patient response to immune checkpoint inhibitor (ICIs) treatment.

Regulation of Colon Cancer Cells Biology by Long Non-Coding RNA Metastasis Associated Lung Adenocarcinoma Transcript 1 (LncRNA MALAT1) via Targeting miR-184

Colon cancer remains a serious threat to human, as lncRNAs and miRNAs are found as crucial components for colon cancer progression and metastasis. But the role of lncRNA MALAT1 in colon cancer remains elusive. Herein, we aimed at investigating its function in the colon cancer and exploring the interaction between MALAT1 and miR-184. We collected tumor tissue specimens from patients with colon cancer and determined the expression of MALAT1 and miR-184 using RTqPCR. Functional experiment was established to detect the impact of MALAT1 siRNA or miR-184 inhibitor, followed by transwell assay and scratch experiment to assess colon cancer cell migration and invasion. Bioinformatics software and luciferase reporter system analyzed the targeting relationship between MALAT1 and miR-184. MALAT1 was up-regulated in colon cancer tissue, while miR-184 was poorly expressed and they were correlated with the clinicopathology of colon cancer ( P &lt;0.05). miR-184 was indicated as the target miRNA of MALAT1. Moreover, silencing of MALAT1 up-regulatedthe expression of miR-184 when activating Caspase3 activity, inhibiting Bcl-2 expression, increasing Bax expression. And MALAT1 siRNA inhibited cancer cell migration and invasion ( P &lt;0.05). However, transfection of miR-184 inhibitor abrogated these effectsinhibitor, when increasing MALAT1 expression. Collectively, we demonstrated that miR-184 is the target miRNA of Lnc-RNA MALAT1 and MALAT1 promotes colon cancer cell progression through inhibition of miR-184.

M6A Methyltransferase METTL3 Reduces Hippocampal Neuron Apoptosis in a Mouse Model of Autism Through the MALAT1/SFRP2/Wnt/β-catenin Axis.

Hippocampal neuron apoptosis contributes to autism, while METTL3 has been documented to possess great potentials in neuron apoptosis. Our study probed into the role of METTL3 in neuron apoptosis in autism and to determine the underlying mechanism. Bioinformatics analysis was used to analyze expressed genes in autism samples. Institute of Cancer Research mice were treated with valproic acid to develop autism models. The function of METTL3 in autism-like symptoms in mice was analyzed with behavioral tests and histological examination of their hippocampal tissues. Primary mouse hippocampal neurons were extracted for in vitro studies. Downstream factors of METTL3 were explored and validated. METTL3, MALAT1, and Wnt/β-catenin signaling were downregulated, while SFRP2 was upregulated in the hippocampal tissues of a mouse model of autism. METTL3 stabilized MALAT1 expression by promoting m6A modification of MALAT1. MALAT1 promoted SFRP2 methylation and led to reduced SFRP2 expression by recruiting DNMT1, DNMT3A, and DNMT3B to the promoter region of SFRP2. Furthermore, SFRP2 facilitated activation of the Wnt/β-catenin signaling. By this mechanism, METTL3 suppressed autism-like symptoms and hippocampal neuron apoptosis. This research suggests that METTL3 can reduce autism-like symptoms and hippocampal neuron apoptosis by regulating the MALAT1/SFRP2/Wnt/β-catenin axis.

Interplay between long non-coding RNA MALAT1 and pyroptosis in diabetic nephropathy patients

Diabetic nephropathy (DN) the most common micro-vascular diabetic complication is the leading cause of end-stage renal disease worldwide. Diagnosis and treatment of DN in its early stage can effectively guard against its progression. Recently, pyroptosis a special type of lytic cell death and noncoding RNA were reported to have roles in early diagnosis and progression of DN. The present study aimed to evaluate the role played by long noncoding RNA (lncRNA) MALAT1, oxidative stress and pyroptosis in early detection of DN. Sixty Type 2 DM patients were included and divided according to urinary albumin-creatinine (UACR) ratio into normoalbuminuria and microalbuminuria groups beside 20 age and sex matched healthy volunteers as controls. Serum caspase 1 and interleukin 18 (IL18) levels were immunoassayed and MALAT1 expression was assessed by real-time PCR. Additionally, glycemic, redox and inflammatory status were assessed. MALAT1 expression, serum caspase1 level, IL18 level, myeloperoxidase activity, and protein carbonyl level were significantly increased in micro-albuinuria diabetic group when compared with diabetic normo-albuminuria group. Meanwhile, catalase activity was significantly decreased. Receiver operating characteristic (ROC) curve analysis revealed that IL18 had the highest sensitivity and diagnostic accuracy for detecting early microalbuminuria and incipient DN followed by caspase1and lastly MALALT1. ConclusionPyroptosis, impaired redox and altered MALAT1 expression could be an underlying mechanism for DN development. Moreover, MALAT1 expression, caspase 1 and IL 18 levels could be regarded as a potential biomarker for early prediction of DN.

MALAT1 promotes platelet activity and thrombus formation through PI3k/Akt/GSK-3β signalling pathway

BackgroundIschaemic stroke and other cardiovascular illnesses are characterised by abnormalities in the processes of thrombosis and haemostasis, which rely on platelet activity. In platelets, a wide variety of microRNAs (long...

Zuo Jin Wan Reverses the Resistance of Colorectal Cancer to Oxaliplatin by Regulating the MALAT1/miR-200s/JNK Signaling Pathway.

Background Oxaliplatin (L-OHP) is a common chemotherapy drug used in the treatment of colorectal cancer (CRC). Our previous work showed that Zuo Jin Wan (ZJW), a traditional Chinese medicine prescription, could improve sensitivity to L-OHP in the treatment of CRC, but the detailed mechanism is not clear. In previous mechanistic studies, we found that the miR-200s expression in CRC is associated with L-OHP sensitivity through regulation of MDR1/p-gp and the downstream c-JunN-terminal kinase (JNK) signaling pathway. Moreover, lncRNA-MALAT1 offers great potential in the regulation of drug resistance by interacting with miR-200s. Therefore, in this work, we explored whether ZJW could reverse L-OHP resistance in CRC by regulating MALAT1, miR-200s, and the downstream signaling pathway. Methods Cell Counting Kit-8 and flow cytometry were used to detect the effects of ZJW combined with L-OHP on chemotherapy tolerance and cell apoptosis of HCT116/L-OHP cells. Western blotting and quantitative real-time PCR (qRT-PCR) were used to detect the activation of the JNK signaling pathway and the protein and mRNA expression levels of the drug resistance-related MDR1/ABCB1 gene in HCT116/L-OHP cells treated with ZJW. The binding sites of MALAT1 and miR-200s were predicted by bioinformatics tools and confirmed by qRT-PCR. qRT-PCR was used to detect the expression of miR-200s and MALAT1 in HCT116/L-OHP cells treated with ZJW. A xenograft model of CRC in nude mice was established to observe the effect of ZJW combined with L-OHP on the growth of subcutaneously transplanted tumors. Apoptosis in tumor cells was detected by TUNEL staining. The activation of the JNK signaling pathway and the expression of drug resistance-related proteins were detected by immunohistochemistry and immunofluorescence. qRT-PCR was used to detect the expression of miR-200s and the MALAT1 gene in the tumors. Results Our study showed that ZJW could significantly decrease the proliferation and promote apoptosis of HCT116/L-OHP cells treated with L-OHP. We further proved that ZJW could reverse the drug resistance of HCT116/L-OHP cells by reducing MALAT1, indirectly upregulating miR-200s, alleviating the activation of the JNK signaling axis, and downregulating the expression of resistance proteins such as MDR1/ABCB1 and ABCG2. ZJW combined with L-OHP inhibited the growth of subcutaneously transplanted tumors and induced apoptosis in nude mice. ZJW reduced the expression of MALAT1 and upregulated the expression of miR-200s in transplanted tumors. In addition, ZJW also alleviated the activation of the JNK signaling pathway while reducing the expression of MDR1/ABCB1 and ABCG2. Conclusions Our study identified that MALAT1 promotes colorectal cancer resistance to oxaliplatin by reducing the miR-200s expression. ZJW may reverse chemoresistance by inhibiting the expression of MALAT1 and regulating the miR-200s/JNK pathway, providing an experimental basis for the clinical application of ZJW in relieving chemotherapy resistance.

Analysis of Long Non-Coding RNA (lncRNA) UCA1, MALAT1, TC0101441, and H19 Expression in Endometriosis.

Endometriosis is a disease of complex etiology. Hormonal, immunological, and environmental factors are involved in its formation. In recent years, special attention has been paid to genetic mechanisms that can have a significant impact on the increased incidence of endometriosis. The study aimed to analyze the expression of four long non-coding RNA (lncRNA) genes, UCA1, MALAT1, TC0101441, and H19, in the context of the risk of developing endometriosis. The material for genetic testing for the expression of lncRNA genes were tissue slices embedded in paraffin blocks from patients with endometriosis (n = 100) and the control group (n = 100). Gene expression was determined by the RT-PCR technique. The expression of the H19 gene in endometriosis patients was statistically significantly lower than in the control group. A statistically significant association was found between H19 gene expression in relation to The Revised American Society for Reproductive Medicine classification of endometriosis (rASRM) in the group of patients with endometriosis. Research suggests that H19 expression plays an important role in the pathogenesis of endometriosis.

Targeting the MALAT1 gene with the CRISPR/Cas9 technique in prostate cancer.

BackgroundThe MALAT1 lncRNA acts as an oncogene in Prostate cancer (PC); thus, it can be severe as a cancer biomarker.MethodsUsing bioinformatics datasets including (HTSeq-Counts, GDC, and TCGA) 5501 gene expression profiling specimens were gathered. Then, expression profiles and sample survival of lncRNA were investigated using COX regression analyses, ROC curve analysis. The Database for Annotation, Visualization, and Integrated Discovery was used to conduct GO and KEGG studies on the lncRNA-related PCGs. After MALAT1 Knockout via CRISPR/Cas9 technique, the MALAT1 expression was assessed in DU-145 cells. The deletion of the target fragment was examined by polymerase chain reaction (PCR). Also, the expression of apoptosis genes was investigated by qRT-PCR. The viability and cell proliferation were measured using the MTT assay. Cell migration capability was determined using the cell scratch assay. The results of qRT-PCR were assessed by the ΔΔCt method, and finally, statistical analysis was performed in SPSS software.ResultsA maximum of 451 lncRNAs were discovered to reflect different expressions between PC and non-carcinoma tissue samples, with 307 being upregulated and 144 being down-regulated. Thirty-six lncRNAs related to OS were carefully selected, which were then subjected to stepwise multivariate Cox regression analysis, with 2 lncRNAs (MALAT1, HOXB-AS3). MALAT1 is highly expressed in PC cells. MALAT1 Knockout in DU-145 cells increases apoptosis and prevents proliferation and migration, and DU-145 transfected cells were unable to migrate based on the scratch recovery test. Overall, data suggest that MALAT1 overexpression in PC helps metastasis and tumorigenesis. Also, MALAT1 knockout can be considered a therapeutic and diagnostic target in PC.ConclusionTargeting MALAT1 by CRISPR/Cas9 technique inhibit the cell proliferation and migration, and in addition induce apoptosis. Thus, MALAT1 can act as a tumor biomarker and therapeutic target.Supplementary InformationThe online version contains supplementary material available at 10.1186/s41021-022-00252-3.

395. EXPRESSION OF MALAT1, MANCR, PSMA3-AS1 AND MIR-101 IN ESOPHAGEAL ADENOCARCINOMA PATIENTS: PRELIMINARY RESULTS OF A CASE–CONTROL STUDY

Abstract Esophageal adenocarcinoma is a leading cause of cancer-related mortality. Ongoing research aims to elucidate the molecular mechanisms underlying the tumorigenesis and progression of esophageal adenocarcinoma and to identify novel therapeutic targets. The abnormal expression of lncRNAs and miRNAs may play an important role in various biological processes in cancer, including immune response, differentiation, angiogenesis, apoptosis, cell proliferation and autophagy. A total of 50 patients who were operated for esophageal adenocarcinoma in our Department from January 2015 to December 2018, were enrolled in the study. Twenty-six healthy individuals that underwent upper gastrointestinal endoscopy were recruited as controls in the study. Total RNA was extracted from esophageal adenocarcinoma tumors, lymph nodes and healthy esophageal tissues using the reverse transcription and qRT-PCR. The expression of different lncRNAs (MALAT1, MANCR, PSMA3-AS1) and miRNA (miR-101) were determined by the 2-ΔΔct method and presented using Fold-Regulation. MALAT1 expression was upregulated in esophageal adenocarcinoma tumors and positive lymph nodes compared to non-cancerous tissues (1.9 and 2.0 times higher than controls respectively). Higher expression of MANCR was also found in esophageal adenocarcinoma tissues and positive lymph nodes compared to controls (2.6 and 2.1 times respectively). MiR-101 was downregulated in esophageal adenocarcinoma tumors and positive lymph nodes compared to controls (16.0 and 7.8 times lower respectively). No significant difference was observed in PSMA3-AS1 expression between esophageal adenocarcinoma tumors or positive lymph nodes and relevant healthy tissues. MALAT1 and MANCR are upregulated in esophageal adenocarcinoma patients while miR-101 is downregulated. Further research in lncRNAs, miRNAs and their interactions with oncogenic pathways may offer new options for the diagnosis, prognosis and therapy of esophageal adenocarcinoma patients.

LncRNA MALAT1 regulates METTL3-mediated PD-L1 expression and immune infiltrates in pancreatic cancer.

Pancreatic cancer is the fourth leading cause of cancer death in the United States. The main methods of treating pancreatic cancer are surgery and chemotherapy, but the treatment efficacy is low with a poor prognosis. Immunotherapy represented by PD-1/PD-L1 has brought a milestone progress in the treatment of pancreatic cancer. However, the unique tumor microenvironment of pancreatic cancer presents challenges for immunotherapy. In addition, m6A is a common RNA modification and a potential molecular target in tumor therapy. The expression pattern of m6A in pancreatic cancer is still unclear. LncRNAs also play an essential role in pancreatic cancer development and treatment. In this study, we found that some m6A regulators were significantly elevated in pancreatic cancer and associated with the expression of PD-1/PD-L1. Moreover, we observed that METTL3 can increase the expression of PD-L1. Notably, METTL3 positively regulates the expression of lncRNA MALAT1 in pancreatic cancer cells. Strikingly, lncRNA MALAT1 increased the expression of PD-L1 in pancreatic cancer cells. This finding indicated that METTL3 regulated the expression of PD-L1 possibly via targeting lncRNA MALAT1 in pancreatic cancer cells. Lastly, MALAT1 governed the viability of pancreatic cancer cells. Taken together, lncRNA MALAT1 is involved in METTL3-mediated promotion of PD-L1 expression in pancreatic cancer.

MiR-188-5p and Host MALAT1 Regulate RBE Cell Migration, Invasion, and Apoptosis via Up-regulating PSMD10 in Cholangiocarcinoma.

The study is designed to explore the regulatory network that MALAT1 competitively binds with miR-188-5p to up-regulate PSMD10 to facilitate cholangiocarcinoma cell migration and invasion and suppress apoptosis. qRT-PCR and fluorescence in situ hybridization (FISH) were used to examine the expression and positive signal of MALAT1 and miR-188-5p in cholangiocarcinoma tissues and HIBEC, HCCC-9810, RBE, and QBC939 cells. Western blot, qRT-PCR, and immunohistochemistry were selected to detect PSMD10 expression in cholangiocarcinoma tissues and cell lines. Dual luciferase reporter gene assay was adopted to verify that miR-188-5p targeted MALAT1 and PSMD10. qRT-PCR, pull down, and western blot were used to examine the regulation of MALAT1-miR-188-5p-PSMD10 axis. Transwell, wound healing assay, and Tunel cell apoptosis were adopted to respectively detect the regulatory abilities of MALAT1-miR-188-5p-PSMD10 axis on cell invasion, migration, and apoptosis. Western blot was used to detect the regulation mechanism of MALAT1 on Bax, Bcl-2, and caspase-3 proteins. Nude mice subcutaneous xenograft model of cholangiocarcinoma was established to examine the impacts of MALAT1 on subcutaneous tumor growth. Immunohistochemistry was adopted to examine the positive indicator of Ki67 antibodies and SMD10 antibodies in each group. MALAT1 and PSMD10 were highly expressed in cholangiocarcinoma tissues and cell lines, while miR-188-5p was lowly expressed. MALAT1 could competitively bind to miR-188-5p, and miR-188-5p could negatively regulate PSMD10. MALAT1, In-miR-188-5p, and PSMD10 could facilitate cell invasion and migration and inhibit apoptosis, while siMALAT1, miR-188-5p, and siPSMD10 produced an opposite result. MALAT1-miR-188-5p-PSMD10 axis could promote RBE cell invasion and migration and inhibit apoptosis, whereas siMALAT1-In-miR-188-5p-siPSMD10 axis showed an opposite result. On the other hand, it was verified that up-regulation/down-regulation of MALAT1 can inhibit/promote Bax and caspase-3 proteins and promote/inhibit the expression of Bcl-2 protein. MALAT1 could facilitate subcutaneous tumor growth and enhance cell proliferation and positive signal of PSMD10, while miR-188-5p worked in an opposite direction. MALAT1 competitively binds to miR-188-5p to up-regulate mRNA translation and protein expression of PSMD10, thereby facilitating cholangiocarcinoma cell invasion and migration and inhibiting its apoptosis. However, interfering MALAT1-miR-188-5p-PSMD10 axis could inhibit the occurrence and development of cholangiocarcinoma.

MALAT1 accelerates proliferation and inflammation and suppresses apoptosis of endometrial stromal cells via the microRNA-142-3p/CXCR7 axis.

MALAT1, microRNA (miR)-142-3p, and CXCR7 are critical molecules mediating endometriosis progression, and their correlation in endometriosis has been barely discussed. Thus, this research sought to survey the impact of MALAT1 on endometrial stromal cell (ESC) proliferation, apoptosis, and inflammation via miR-142-3p/CXCR7 axis to promote explorations on endometriosis. In endometrial tissues and ESCs, CXCR7 expression was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis and miR-142-3p and MALAT1 expression by qRT-PCR. Then, ESC proliferation was assessed by CCK-8 and EdU labeling assays, apoptosis by flow cytometry, and levels of inflammatory factors tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in ESC supernatant by enzyme linked immunosorbent assay. The interactions among CXCR7, miR-142-3p, and MALAT1 were evaluated by dual luciferase reporter gene, RNA pull-down, and Argonaute 2- RNA immunoprecipitation assays. At last, the relevance of miR-142-3p to MALAT1 and that of miR-142-3p to CXCR7 in ectopic endometrial tissues were analyzed using Pearson correlation analysis. CXCR7 and MALAT1 were overexpressed whilst miR-142-3p was lowly expressed in ectopic endometrial tissues. CXCR7 silencing or miR-142-3p overexpression reduced proliferative ability and enhanced apoptosis rate in ESCs and decreased TNF-α, IL-1β, and IL-6 levels in cell supernatant. miR-142-3p negatively targeted CXCR7 while MALAT1 negatively targeted miR-142-3p. However, MALAT1 silencing diminished ESC proliferation and TNF-α, IL-1β, and IL-6 levels in ESC supernatant and elevated ESC apoptosis, which was counterweighed by inhibiting miR-142-3p. Conclusively, MALAT1 promoted ESC proliferation and inflammatory factor expression and inhibited ESC apoptosis via miR-142-3p/CXCR axis.

Malat1 attenuated the rescuing effects of docosahexaenoic acid on osteoarthritis treatment via repressing its chondroprotective and chondrogenesis activities

Osteoarthritis (OA) is a degenerative disease associated with joint inflammation, articular cartilage degeneration and subchondral hypertrophy. Small molecules which both ameliorate chondrocyte OA phenotype and activate bone marrow-derived mesenchymal stem cells (BMSCs) chondrogenesis under inflammatory conditions have the therapeutical potential for OA treatment. In this study, we characterized a novel small molecule which could ameliorate OA progression via novel regulating mechanisms. Docosahexaenoic acid (DHA), a bioactive molecule, was screened from a small molecule library and showed anti-inflammatory and chondroprotective effects in OA chondrocytes, as well as ameliorated IL-1β impaired BMSCs chondrogenesis in Wnt/β-catenin and NF-κB signaling dependent manners. Furthermore, Malat1 was found to be the key mediator of DHA-mediating anti-inflammation chondroprotection and chondrogenesis. DHA also rescued cartilage loss and damage in a surgery-induced OA mice model. The elevation of serum Malat1 levels caused by OA was also downregulated by DHA treatment. Taken together, our findings demonstrated that DHA, with a dual-signaling repression property, exerted its anti-inflammation, chondroprotection and chondrogenesis function possibly via regulating Malat1 level, suggesting that it may be a possible drug candidate for OA patients with elevated MALAT1 expression levels.

513 Regulatory roles of lncRNAs in psoriasis determined by single cell analysis

Long noncoding RNAs (lncRNAs) can harbor DNA binding domains and regulate target gene expressions by binding to their promoter regions. Although a large proportion of differentially expressed lncRNAs have been identified in psoriatic skin, a chronic inflammatory disease enriched in pro-inflammatory genes, their cell type and disease specificity are yet to be revealed. We performed scRNA-seq experiments in non-lesional skin and lesional skin from 6 psoriasis patients, and compared the expression profiles of lncRNAs against skin from 5 control samples. Most of the up-regulated lncRNA were enriched in keratinocytes (for example, MALAT1 and NEAT1), fibroblasts (MEG3), or melanocytes (KU-MEL-3). However, many of these differentially expressed lncRNAs do not yet have known functional roles. We conducted a in silico analysis to assay the DNA binding ability for 121 differentially expressed lncRNA in psoriasis lesional/non-lesional against control (FDR<=5%) within each of the 12 cell types, revealing 5,879 potential downstream protein-coding gene targets. We identified that the lncRNAs NEAT1 and MALAT1 (known to perform regulatory roles) targets include epidermal genes such as: PPP1R15A, ZFP36, and SFN, which are responsible for cell cycle regulation and cell proliferation. Notably, these target genes are all correlated with MALAT1 and NEAT only in the lesional skin, but not the non-lesional/control keratinocytes. In addition, MALAT1 is also co-expressed with other binding targets JUN, and JUNB, which are involved in pro-inflammatory response within psoriasis (R≥0.35, p<2.2e-16). Interestingly, within the control and non-lesional keratinocytes, MALAT1 expression was negatively correlated with binding targets including DMKN (pro-inflammatory), and FABP5(proliferation gene) (R<= 0.4, p<2.2e-16). Together, these findings highlight how insight from co-expression analysis can contextualize the functional role of lncRNAs within a gene regulatory network.

LncRNA MALAT1 from human adipose-derived stem cell exosomesaccelerates wound healing via miR-378a/FGF2 axis.

Aim: The effects of MALAT1from human adipose-derived stem cell(ADSC) exosomes in skin wound healingwere investigated. Material & methods: The viability, apoptosisand migration ability of human skin fibroblasts (HSFs) were evaluated by Cell Counting Kit-8 assay, flow cytometryand scratch assay, respectively. A mouse model was established to evaluate the role of exosomal MALAT1 in skin wound healing in vivo. Results: Human ADSC exosomes promoted the proliferation and migration of HSFs and increased MALAT1 expression. MALAT1 silencing in human ADSCs inhibited HSF viability and migration, promoted HSF apoptosisand inhibited angiogenesis by upregulating miR-378a. Overexpression of miR-378a inhibited the migration and proliferation of HSFs by downregulating FGF2expression. ADSC exosomes promoted skin wound healing by mediating MALAT1 in vivo. Conclusion: Exosomal MALAT1 accelerated skin wound healing by regulating the miR-378a/FGF2 axis, suggesting that MALAT1 might be used as a potential target for cutaneous wound treatment.

Early-stage colon cancer with high MALAT1 expression is associated with the 5-Fluorouracil resistance and future metastasis.

This study aimed to investigate the role of long noncoding RNA (LncRNA) expression profiles to predict relapse and 5-FU response in patients with stage I/II colon cancer (CC). The expression level of 15 LncRNA was analyzed in stage I/II colon tumors of 126 CC patients. To confirm the findings in-vitro, 5FU-resistant HT29 cells were generated by subjecting HT-29 cells to the increasing concentrations of 5FU for 6months. The 5FU resistance was observed in WST-1 and Annexin V analyses. The colony formation and wound healing assays were assessed to determine the metastatic properties of the cells. Expression levels of LncRNAs and mRNA of EMT-related genes were determined by RT-PCR. The role of LncRNA on metastasis and 5FU sensitivity were confirmed in pcDNA3.0-PTENP1 and si-MALAT1 expressed 5FU-resistant HT29 cell lineages. High MALAT1 (p = 0.0002) and low PTENP1 (p = 0.0044) expressions were significantly associated with 5-FU resistance and tumor relapse in stage I/II CC. The invasiveness and colony-forming characteristics of 5-FU-resistant cell lineages were higher as compared to the parent HT-29. Moreover, the expression of MALAT1 (p = 0.0009) was increased while the expression of PTENP1 (p = 0.0158) decreased in 5FU-resistant-HT-29 cells. Si-MALAT1 treatment increased cell sensitivity to 5FU, whereas it decreased invasive behaviors of 5 FU-resistant-HT-29 cells. MALAT1 may be a biomarker in predicting recurrence in early-stage CC. Our findings suggest that a cell-based therapy to target MALAT1 could be established for these patients to prevent metastasis and 5-FU resistance.