RBM33 directs the nuclear export of transcripts containing GC-rich elements.

Although splicing is a major driver of RNA nuclear export, many intronless RNAs are efficiently exported to the cytoplasm through poorly characterized mechanisms. For example, GC-rich sequences promote nuclear export in a splicing-independent manner, but how GC content is recognized and coupled to nuclear export is unknown. Here, we developed a genome-wide screening strategy to investigate the mechanism of export of NORAD, an intronless cytoplasmic long noncoding RNA (lncRNA). This screen revealed an RNA binding protein, RBM33, that directs the nuclear export of NORAD and numerous other transcripts. RBM33 directly binds substrate transcripts and recruits components of the TREX-NXF1/NXT1 RNA export pathway. Interestingly, high GC content emerged as the feature that specifies RBM33-dependent nuclear export. Accordingly, RBM33 directly binds GC-rich elements in target transcripts. These results provide a broadly applicable strategy for the genetic dissection of nuclear export mechanisms and reveal a long-sought nuclear export pathway for transcripts with GC-rich sequences.

SAM68 is required for regulation of Pumilio by the NORAD long noncoding RNA.

The number of known long noncoding RNA (lncRNA) functions is rapidly growing, but how those functions are encoded in their sequence and structure remains poorly understood. NORAD (noncoding RNA activated by DNA damage) is a recently characterized, abundant, and highly conserved lncRNA that is required for proper mitotic divisions in human cells. NORAD acts in the cytoplasm and antagonizes repressors from the Pumilio family that bind at least 17 sites spread through 12 repetitive units in NORAD sequence. Here we study conserved sequences in NORAD repeats, identify additional interacting partners, and characterize the interaction between NORAD and the RNA-binding protein SAM68 (KHDRBS1), which is required for NORAD function in antagonizing Pumilio. These interactions provide a paradigm for how repeated elements in a lncRNA facilitate function.

Long non-coding RNA NORAD regulates megakaryocyte differentiation and proplatelet formation via the DUSP6/ERK signaling pathway.

Megakaryopoiesis and platelet production is a complex process that is underpotential regulation at multiple stages. Many long non-coding RNAs (lncRNAs) are distributed in hematopoietic stem cells and platelets. lncRNAs may play important roles as key epigenetic regulators in megakaryocyte differentiation and proplatelet formation. lncRNA NORAD can affect cell ploidy by sequestering PUMILIO proteins, although its direct effect on megakaryocyte differentiation and thrombopoiesis is still unknown. In this study, we demonstrate NORAD RNA is highly expressed in the cytoplasm during megakaryocyte differentiation. Interestingly, we identified for the first time that NORAD has a strong inhibitory effect on megakaryocyte differentiation and proplatelet formation from cultured megakaryocytes. DUSP6/ERK1/2 pathway is activated in response to NORAD knockdown during megakaryocytopoiesis, which is achieved by sequestering PUM2 proteins. Finally, compared with the wild-type control mice, NORAD knockout mice show a faster platelet recovery after severe thrombocytopenia induced by 6 Gy total body irradiation. These findings demonstrate lncRNA NORAD has a key role in regulating megakaryocyte differentiation and thrombopoiesis, which provides a promising molecular target for the treatment of platelet-related diseases such as severe thrombocytopenia.

METTL3-mediated m6A modification of NORAD inhibits the ferroptosis of vascular smooth muscle cells to attenuate the aortic dissection progression in an YTHDF2-dependent manner.

Ferroptosis of vascular smooth muscle cells (VSMCs) is related to the incidence of aortic dissection (AD). Long non-coding RNA (lncRNA) NORAD plays a crucial role in the progression of various diseases. The present study aimed to investigate the effects of NORAD on the ferroptosis of VSMCs and the molecular mechanisms. The expression of NORAD, HUR, and GPX4 was detected using quantitative real-time PCR (qPCR) or western blot. Ferroptosis was evaluated by detecting lactate dehydrogenase (LDH) activity, lipid reactive oxygen species (ROS), malonaldehyde (MDA) content, L-Glutathione (GSH) level, Fe2+ content, and ferroptosis-related protein levels. The molecular mechanism was assessed using RNA pull-down, RNA-binding protein immunoprecipitation (RIP), and luciferase reporter assay. The histology of aortic tissues was assessed using H&E, elastic Verhoeff-Van Gieson (EVG), and Masson staining assays. The data indicated that NORAD was downregulated in patients with AD and AngII-treated VSMCs. Overexpression of NORAD promoted VSMC growth and inhibited the ferroptosis induced by AngII. Mechanistically, NORAD interacted with HUR, which promoted GPX4 mRNA stability and elevated GPX4 levels. Knockdown of GPX4 abrogated the effects of NORAD on cell growth and ferroptosis of AngII-treated VSMCs. Moreover, METTL3 promoted m6A methylation of NORAD in an YTHDF2-dependent manner. In addition, NORAD attenuated AAD symptoms, incidence, histopathology, inflammation, and ferroptosis in AAD mice. In conclusion, METTL3-mediated NORAD inhibited ferroptosis of VSMCs via the HUR/GPX4 axis and decelerated AAD progression, suggesting that NORAD may be an AD therapeutic target.

Diagnostic and prognostic potential of long non-coding RNA NORAD in patients with acute deep vein thrombosis and its role in endothelial cell function.

BACKGROUND: Deep venous thrombosis (DVT) is the common clinical cardiovascular disease, and easily develops into post-thrombotic syndrome (PTS). The study aimed to examine the clinical value of long non-coding RNA NORAD gene in the development of DVT and PTS. In vitro, the underlying mechanism was explored. METHODS: Serum levels of lncRNA NORAD gene in 85 DVT cases and 85 healthy individuals were tested. The role of lncRNA NORAD gene in human umbilical vein endothelial cells (HUVECs) proliferation, migration and inflammation was examined. The candidate downstream target gene was predicted via bioinformatic analysis. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were done for the function annotation and pathway enrichment. RESULTS: LncRNA NORAD gene was at high expression in the serum of DVT patients, it can distinguish DVT patients from healthy controls with the area under the curve of 0.919. Elevated expression of lncRNA NORAD gene in PTS patients was detected, DVT cases with high expression of lncRNA NORAD gene were more susceptible to PTS. LncRNA NORAD gene knockdown promoted HUVECs' proliferation, migration while suppressing cell apoptosis and inflammation. MiR-93-5p served as a target of lncRNA NORAD gene, and its overexpression reversed the role of lncRNA NORAD gene in the biological function of HUVECs. The target genes of miR-93-5p were enriched in HIF-1 signaling, TGF-beta signaling and PI3K-Akt signaling, protein-protein interaction (PPI) network indicated STAT3, MAPK1 to be the key targets. CONCLUSIONS: Upregulation of expression of lncRNA NORAD gene was a potential diagnostic biomarker for DVT and related to the development of PTS. LncRNA NORAD/miR-93-5p axis was involved in the progress of DVT through regulating endothelial cell function.

lncRNA NORAD alleviates dysfunction of renal proximal tubular epithelial cells during the sepsis-associated acute kidney injury by modulating the miR-155-5p-PDK1 axis.

The sepsis-associated acute kidney injury (Sa-AKI) is closely related to high mortality rates worldwide. Injury to the renal proximal tubular epithelial cells (RPTECs), caused by pathological conditions, is a major cause of acute kidney injury (AKI). The lncRNA NORAD has been reported to be positively associated with kidney cancers. However, the biological roles and underlying mechanisms of NORAD in RPTECs during AKI are still unclear. In this study, we found that NORAD was significantly downregulated in RPTECs from AKI tissues. Overexpression of NORAD alleviated RPTECs injury induced by lipopolysaccharide (LPS). Additionally, glucose metabolism was significantly impaired during AKI, and LPS treatment inhibited glucose metabolism in RPTECs. We demonstrated that NORAD rescued the LPS-induced inhibition of glucose metabolism in RPTECs. Furthermore, miRNA-155-5p was significantly upregulated in RPTECs from AKI. Through bioinformatics analysis, RNA pull-down, RNA IP, and luciferase assays, we showed that NORAD directly associated with miR-155-5p to downregulate its expression. Moreover, overexpression of miR-155-5p inhibited glucose metabolism by directly targeting the 3'UTR of the glucose metabolism enzyme, pyruvate dehydrogenase kinase 1 (PDK1). Finally, rescue experiments validated that NORAD's protective effect on RPTECs injury was mediated through modulation of the miR-155-5p-PDK1-glucose metabolism pathway. In summary, these results reveal that lncRNA NORAD can alleviate RPTECs dysfunction by targeting the miR-155-5p-PDK1 axis, suggesting that NORAD has the potential to contribute to the development of therapeutic approaches against Sa-AKI.

Gain-Type Aneuploidies Influence the Burden of Selective Long Non-Coding Transcripts in Colorectal Cancer.

Chromosomal instability is a hallmark of colorectal carcinogenesis and produces an accumulation of different forms of aneuploidies or broad copy number aberrations. Colorectal cancer is characterized by gain-type broad copy number aberrations, specifically in Chr20, Chr8q, Chr13 and Chr7, but their roles and mechanisms in cancer progression are not fully understood. It has been suggested that broad copy number gains might contribute to tumor development through the so-called caricature transcriptomic effect. We intend to investigate the impact of broad copy number gains on long non-coding RNAs' expression in colorectal cancer, given their well-known role in oncogenesis. The influence of such chromosomal aberrations on lncRNAs' transcriptome profile was investigated by SNP and transcriptome arrays in our series of colorectal cancer samples and cell lines. The correlation between aneuploidies and transcriptomic profiles led us to obtain a class of Over-UpT lncRNAs, which are transcripts upregulated in CRC and further overexpressed in colon tumors bearing specific chromosomal aberrations. The identified lncRNAs can contribute to a wide interaction network to establish the cancer driving effect of gain-type aneuploidies.

Exploration of the mechanism of NORAD activation of TGF-ß1/Smad3 through miR-136-5p and promotion of tacrolimus-induced renal fibrosis.

BACKGROUND: Tacrolimus is a potent immunosuppressant, but has various side effects, with nephrotoxicity being the most common. Renal fibrosis is an important process of tacrolimus nephrotoxicity. Therefore, it is important to identify the factors that contribute to renal fibrosis after tacrolimus nephrotoxicity, and control its development. METHODS: The present study aims to determine whether tacrolimus may speed up the course of renal fibrosis by upregulating noncoding RNA activated by DNA damage (NORAD) to compete with miR-136-5p, and activating the TGF-ß1/Smad3 pathway. Furthermore, in vivo rat models and in vitro cell models were established. Then, the expression levels of NORAD and miR-136-5p were determined by RT-qPCR, while the expression of the TGF-ß1/Smad3 pathway was determined by western blot and RT-qPCR. In order to investigate the interaction between NORAD and miR-136-5p, as well as miR-136-5p and SYK, two luciferase reporters were employed. The renal fibrosis of mice was observed using Masson and PAS staining. The expression of inflammatory factors IL-1, IL-6, MCP-1 and TNF-α was detected by ELISA. RESULTS: In the in vitro experiments, NORAD was upregulated, while miR-136-5p was downregulated after tacrolimus induction. The expression of the TGF-ß1/Smad3 pathway correspondingly changed after the induction by tacrolimus. In the in vivo experiments, the expression of NORAD and miR-136-5p, and the trend for renal fibrosis were consistent with the results in the in vitro experiments. Furthermore, the inflammatory factors correspondingly changed with the severity of renal fibrosis. Moreover, the expression trend of the TGF-ß1/Smad3 pathway in tacrolimus-induced rats was consistent with that in the in vitro experiments. CONCLUSION: Through in vitro and in vivo experiments, the present study was able to successfully prove that tacrolimus upregulates NORAD to compete with miR-136-5p, resulting in a decrease in miR-136-5p expression, which in turn activates the TGF-ß1/smad3 pathway, and finally induces the aggravation of renal fibrosis.

LncRNA NORAD deficiency alleviates kidney injury in mice and decreases the inflammatory response and apoptosis of lipopolysaccharide-stimulated HK-2 cells via the miR-577/GOLPH3 axis.

BACKGROUND: Long noncoding RNAs (lncRNAs) are significant regulators for sepsis-associated acute kidney injury (AKI). Noncoding RNA activated by DNA damage (NORAD) is highly expressed in the serum of patients with neonatal sepsis. We aimed to reveal the role of NORAD in sepsis-associated AKI. METHODS AND RESULTS: In this study, we established an AKI mouse model by cecal ligation and puncture (CLP) method and used the lipopolysaccharide (LPS)-stimulated HK-2 cells as the in vitro model of AKI. We identified the upregulation of NORAD expression in AKI mice and LPS-treated HK-2 cells. Silencing of NORAD alleviated renal injury by suppressing inflammation and apoptosis in vivo. The influences of NORAD suppression on cell apoptosis and inflammatory response in LPS-treated HK-2 cells were investigated by TUNEL and western blotting. NORAD deficiency inhibited HK-2 cell apoptosis and relieved the inflammation. Moreover, we explored the underlying mechanism by which NORAD regulates HK-2 cells. MiR-577 was verified to directly bind to NORAD, and GOLPH3 was identified as a target downstream miR-577. In addition, GOLPH3 overexpression countervailed the impacts of NORAD downregulation on apoptosis and inflammation in vitro. CONCLUSIONS: Our findings revealed that NORAD knockdown alleviates kidney injury in mice and decreases the inflammatory response and apoptosis of LPS-stimulated HK-2 cells via the miR-577/GOLPH3 axis.

NORAD-sponged miR-378c alleviates malignant behaviors of stomach adenocarcinoma via targeting NRP1.

BACKGROUND: Stomach adenocarcinoma (STAD) is the most common type of gastric cancer (GC), with a high recurrence rate and poor prognosis, but the potential indicators for STAD are insufficient. METHODS: Herein, we found that MicroRNA-378c (miR-378c) was lowly expressed in STAD, and the low expression of miR-378c was highly correlated with poor overall survival (OS), T stage, Reflux history, DSS events and PFI events of STAD patients. RESULTS: In addition, univariate analysis displayed that miR-378c was significantly associated with OS (Hazard ratio 0.735; 95% CI, 0.542-0.995; P = 0.046). Furthermore, it was validated that miR-378c inhibition accelerated STAD cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), while they were suppressed by miR-378c overexpression. Mechanistically, Neuropilin 1 (NRP1) was confirmed as the target of miR-378c, and Lnc-NORAD was identified as its sponger. More importantly, NORAD-mediated miR-378c inhibited malignant behaviors of STAD both in vitro and in vivo. CONCLUSIONS: Collectively, these results suggest miR-378c as a promising indicator for the treatment of STAD.

Diagnostic value of lncRNA NORAD in pulmonary tuberculosis and its regulatory role in Mycobacterium tuberculosis infection of macrophages.

Pulmonary tuberculosis (PTB) infection is a chronic inflammatory response caused by Mycobacterium tuberculosis (Mtb). The purpose of this study was to confirm the value of long noncoding RNA NORAD (noncoding RNA activated by DNA damage) in the diagnosis of PTB and to explore its mechanism in Mtb-infected macrophages. NORAD serum levels were estimated by qRT-PCR in 90 patients with PTB and 85 healthy individuals. Receiver operating characteristic curves were plotted to assess the diagnostic value of NORAD in PTB. Human and murine macrophages were infected with Mtb strain H37Rv. CCK-8 (a cell counting kit) and ELISA detected viability of macrophages and inflammatory cytokine secretion, respectively. A dual-luciferase reporter assay was performed to analyze the relationship between NORAD and microRNA (miR)-618. NORAD was significantly elevated in patients with PTB, and its positivity was correlated with levels of inflammatory cytokines IL-1 ß (r = 0.854), TNF-α (r = 0.617), and IL-6 (r = 0.585). With an area under the curve of 0.918, and sensitivity and specificity of 80.0% and 89.4%, respectively, NORAD remarkedly differentiated patients with PTB from healthy individuals. Furthermore, Mtb infection significantly increased NORAD levels in THP-1 and RAW264.7 cells and increased their viability and inflammation (P < 0.001). However, this increased effect was weakened by reduced NORAD levels. Dual-luciferase reporter assay results confirmed that miR-618 in macrophages is a target miRNA for NORAD and can be negatively regulated by it. Moreover, elevated miR-618 suppressed macrophage viability and inflammation in Mtb infection. NORAD is a potential diagnostic biomarker for PTB and is involved in Mtb-infected macrophage activity and inflammation by targeting miR-618.

Suppression of lncRNA NORAD may affect cell migration and apoptosis in gastric cancer cells.

BACKGROUND: Gastric cancer (GC) is a major malignancy that threatens people's lives worldwide. Long noncoding RNA (lncRNA) non-coding RNA activated by DNA damage (NORAD) is known to be a potential oncogene in many cancers and may promote cell migration and metastasis, and decrease apoptosis rate. MATERIAL AND METHODS: NORAD expression was measured in 70 pairs of GC tissues and their adjacent normal tissues (ANTs) by quantitative real-time polymerase chain reaction. Si-NORAD gene knockdown study and cellular assays were conducted to assess the correlation between NORAD expression and cell viability, apoptosis, migration, and metastasis. RESULTS: NORAD was significantly overexpressed in GC tissues compared to ANTs (P value < 0.0001). The receiver operating characteristic curve indicated the AUC of 0.721 with the sensitivity and specificity of 78.57 and 61.43, respectively (P value < 0.0001). NORAD downregulation leads to decreased cell viability (P value < 0.001) and migration (P value < 0.01), increased apoptosis rate (P value < 0.0001), and increased protein level for PTEN, E-cadherin, and Bax, but decreased protein level for Bcl-2. CONCLUSION: Generally, NORAD may serve as a potential diagnostic biomarker in GC.

Increased long non-coding RNA NORAD reflects serious cardiovascular stenosis, aggravated inflammation status, and higher lipid level in coronary heart disease.

OBJECTIVE: Long non-coding RNA activated by DNA damage (lnc-NORAD) modulates inflammation, lipid level, and atherosclerosis in various cardiovascular diseases. This study intended to investigate the dysregulated expression of lnc-NORAD, and its linkage with clinical characteristics, inflammatory cytokines, and accumulating major adverse cardiovascular events (MACE) in coronary heart disease (CHD) patients. METHODS: Totally, 160 CHD patients, 30 disease controls (DCs), and 30 healthy controls (HCs) were included. The reverse transcription-quantitative polymerase chain reaction was used to detect lnc-NORAD expression in peripheral blood mononuclear cell samples from all participants. Enzyme-linked immunosorbent assay was applied to detect proinflammatory cytokines and adhesion molecules in CHD patients. Then, MACE was recorded during a median follow-up of 12 (range: 1.0-27.0) months. RESULTS: Lnc-NORAD was highest in CHD patients, followed by DCs, and lowest in HCs (p < 0.001). In CHD patients, lnc-NORAD was positively linked with Gensini score (p = 0.001). Meanwhile, lnc-NORAD was positively linked to C-reactive protein (p = 0.023), tumor necrosis factor-alpha (p = 0.016), interleukin (IL)-6 (p = 0.003), IL-8 (P = 0.018), and IL-17A (p = 0.029). No relation of lnc-NORAD with vascular cell adhesion molecule-1 (p = 0.094) and intercellular adhesion molecule-1 (p = 0.060) was found. Furthermore, lnc-NORAD was positively related to total cholesterol (p = 0.014) and low-density lipoprotein cholesterol (p = 0.004), whereas lnc-NORAD was not linked to triglyceride (p = 0.103) and high-density lipoprotein cholesterol (p = 0.533). However, lnc-NORAD (high vs. low), and its higher quartiles were both not linked to accumulating MACE rate (p > 0.05). CONCLUSION: Increased lnc-NORAD is linked with aggravated stenosis degree, inflammation status, and blood lipid in CHD patients. However, further validation is required.

LncRNA NORAD promotes the progression of myocardial infarction by targeting the miR-22-3p/PTEN axis.

NORAD is a newly identified long non-coding RNA (lncRNA) that plays an important role in cancers. NORAD has been found to be highly expressed in the mouse model of acute myocardial infarction (AMI). However, the role of NORAD in the regulation of AMI remains unknown. In the present study, we aimed to investigate the function of NORAD in AMI and explore the potential regulatory mechanisms. A mouse model of AMI was established and NORAD was knocked-down. The infarcted size of heart tissues and the cardiac function were evaluated. In addition, two cardiomyocyte cell lines were treated with hypoxia/re-oxygenation (H/R) to mimic AMI . Luciferase reporter assay, RNA pull-down assay, fluorescence hybridization, qRT-PCR, and western blot analysis were performed. Apoptotic cells and the levels of L-lactate dehydrogenase (LDH) and malondialdehyde (MDA) were detected. Our results show that downregulation of NORAD efficiently attenuates heart damage in the AMI mouse model. NORAD interacts with miR-22-3p. Knock-down of NORAD inhibits H/R-induced cell apoptosis and reduces LDH and MDA levels, while its effects are abolished by miR-22-3p inhibitor. MiR-22-3p interacts with PTEN and inhibits its expression. Overexpression of miR-22-3p inhibits H/R-induced cell apoptosis and reduces LDH and MDA levels, while its effects are abolished by overexpression of PTEN. Finally, overexpression of NORAD inhibits the AKT/mTOR signaling pathway, and its effects are attenuated by overexpression of miR-22-3p. Taken together, our study reveals that NORAD promotes the progression of AMI by regulating the miR-22-3p/PTEN axis, and the AKT/mTOR signaling may also be involved in the regulatory processes.

Investigation of the expression level of long non-coding RNAs in dental follicles of impacted mandibular third molars.

OBJECTIVES: Dental follicle (DF) is made up of mesenchymal cells and fibers surrounding the enamel organ of a developing tooth. It has been shown that cystic and neoplastic lesions can develop from the pericoronal follicles of impacted third molars (ITMs). But the molecular transformation of DF tissues has not yet been uncovered and remains elusive. Accordingly, in the present study, we aimed to investigate the differential expression of lncRNA genes in DF tissues associated with asymptomatic impacted mandibular third molars (IMTMs) that do not show pathological pericoronal radiolucency in radiographic examination. MATERIAL AND METHODS: A total of 30 patients with unilateral mesioangular IMTMs were enrolled for the study. The expressions of lncRNA genes were determined in the DF and healthy gingival tissues obtained from study patients. For the determination of lncRNA expression levels, RNA was isolated from the obtained tissues, converted to cDNA samples, and analyzed by quantitative real-time PCR method. RESULTS: As a result, we found that the gene expression of MEG3 was increased about 10-fold in DF tissues compared to healthy gingival tissues (p < 0.0001). In addition, NORAD expression was found to be upregulated 4.2-fold (p = 0.0002) in DF tissues. Also, expression level of MALAT1 was found to be decreased 1.24-fold (p = 0.584) and TP73-AS1 increased 2.6-fold (p = 0.093) in DF tissues compared to healthy gingival tissues. CONCLUSIONS: Consequently, present findings suggest that differentially expressed lncRNAs in DFs might be associated with the various levels of cellular events including osteogenic differentiation, DNA damage, and the transformation into odontogenic pathology. CLINICAL RELEVANCE: Expression levels of MEG3 and NORAD lncRNA molecules may guide clinicians in the evaluation of asymptomatic ITM dental follicles that cannot be determined radiologically and during extraction of these teeth for prophylactic purposes.

Long non-coding RNA NORAD/miR-224-3p/MTDH axis contributes to CDDP resistance of esophageal squamous cell carcinoma by promoting nuclear accumulation of ß-catenin.

BACKGROUND: Cis-diamminedichloro-platinum (CDDP)-based chemotherapy regimens are the most predominant treatment strategies for patients with esophageal squamous cell carcinoma (ESCC). Dysregulated long non-coding RNAs (lncRNAs) contribute to CDDP resistance, which results in treatment failure in ESCC patients. However, the majority of lncRNAs involved in CDDP resistance in ESCC remain to be elucidated. METHODS: The public Gene Expression Omnibus (GEO) dataset GSE45670 was analysed to reveal potential lncRNAs involved in CDDP resistance of ESCC. Candidate upregulated lncRNAs were detected in ESCC specimens by qRT-PCR to identify crucial lncRNAs. Non-coding RNA activated by DNA damage (NORAD) was selected for further study. Kaplan-Meier analysis and a COX proportional regression model were performed to analyse the potential of NORAD for predicting prognosis of ESCC patients. The role of NORAD in CDDP resistance were determined by conducting gain and loss-of-function experiments in vitro. Fluorescence in situ hybridization (FISH) was performed to determine the subcellular location of NORAD in ESCC cells. A public GEO dataset and bioinformatic algorithms were used to predict the microRNAs (miRNAs) that might be latently sponged by NORAD. qRT-PCR was conducted to verify the expression of candidate miRNAs. Luciferase reporter and Argonaute-2 (Ago2)-RNA immunoprecipitation (RIP) assays were conducted to evaluate the interaction between NORAD and candidate miRNAs. A miRNA rescue experiment was performed to authenticate the NORAD regulatory axis and its effects on CDDP resistance in ESCC cells. Western blotting was conducted to confirm the precise downstream signalling pathway of NORAD. A xenograft mouse model was established to reveal the effect of NORAD on CDDP resistance in vivo. RESULTS: The expression of NORAD was higher in CDDP-resistant ESCC tissues and cells than in CDDP-sensitive tissues and cells. NORAD expression was negatively correlated with the postoperative prognosis of ESCC patients who underwent CDDP-based chemotherapy. NORAD knockdown partially arrested CDDP resistance of ESCC cells. FISH showed that NORAD was located in the cytoplasm in ESCC cells. Furthermore, overlapping results from bioinformatic algorithms analyses and qRT-PCR showed that NORAD could sponge miR-224-3p in ESCC cells. Ago2-RIP demonstrated that NORAD and miR-224-3p occupied the same Ago2 to form an RNA-induced silencing complex (RISC) and subsequently regulated the expression of metadherin (MTDH) in ESCC cells. The NORAD/miR-224-3p/MTDH axis promoted CDDP resistance and progression in ESCC cells by promoting nuclear accumulation of ß-catenin in vitro and in vivo. CONCLUSIONS: NORAD upregulates MTDH to promote CDDP resistance and progression in ESCC by sponging miR-224-3p. Our results highlight the potential of NORAD as a therapeutic target in ESCC patients receiving CDDP-based chemotherapy.

Long non-coding RNA NORAD promotes pancreatic cancer stem cell proliferation and self-renewal by blocking microRNA-202-5p-mediated ANP32E inhibition.

BACKGROUND: Cancer stem cells (CSCs) are key regulators in the processes of tumor initiation, progression, and recurrence. The mechanism that maintains their stemness remains enigmatic, although the role of several long noncoding RNAs (lncRNAs) has been highlighted in the pancreatic cancer stem cells (PCSCs). In this study, we first established that PCSCs overexpressing lncRNA NORAD, and then investigated the effects of NORAD on the maintenance of PCSC stemness. METHODS: Expression of lncRNA NORAD, miR-202-5p and ANP32E in PC tissues and cell lines was quantified after RNA isolation. Dual-luciferase reporter assay, RNA pull-down and RIP assays were performed to verify the interactions among NORAD, miR-202-5p and ANP32E. We then carried out gain- and loss-of function of miR-202-5p, ANP32E and NORAD in PANC-1 cell line, followed by measurement of the aldehyde dehydrogenase activity, cell viability, apoptosis, cell cycle distribution, colony formation, self-renewal ability and tumorigenicity of PC cells. RESULTS: LncRNA NORAD and ANP32E were upregulated in PC tissues and cells, whereas the miR-202-5p level was down-regulated. LncRNA NORAD competitively bound to miR-202-5p, and promoted the expression of the miR-202-5p target gene ANP32E thereby promoting PC cell viability, proliferation, and self-renewal ability in vitro, as well as facilitating tumorigenesis of PCSCs in vivo. CONCLUSION: Overall, lncRNA NORAD upregulates ANP32E expression by competitively binding to miR-202-5, which accelerates the proliferation and self-renewal of PCSCs.

LncRNA NORAD, sponging miR-363-3p, promotes invasion and EMT by upregulating PEAK1 and activating the ERK signaling pathway in NSCLC cells.

Lung cancer is one of the most common malignant tumors in the world. Non-small cell lung cancer (NSCLC) accounts for about 80% of all lung cancers. About 75% of patients are in the middle and advanced stages at the time of discovery, and the 5-year survival rate is very low. The aim of this study was to investigate the role of long non-coding RNA (lncRNA) NORAD in the pathogenesis of NSCLC. We found that lncRNA NORAD was highly expressed in human NSCLC tissues and cell lines. The CCK-8 assay results showed that lncRNA NORAD had no effect on cell proliferation. The Transwell assay and Western blotting results showed that overexpression of lncRNA NORAD promoted the invasion and epithelial-mesenchymal transition (EMT) of NSCLC cells. Then bioinformatics analysis was used to screen for candidate miRNA bound with lncRNA NORAD and the target gene of miRNA in NSCLC. The luciferase reporter gene assay and RNA pull-down assay were used to verify the relationship. We found that miR-363-3p expression was down-regulated, whereas PEAK1 expression was upregulated in NSCLC cells. We performed gain and loss function test of lncRNA NORAD, miR-363-3p and PEAK1, the results showed that while miR-363-3p-mimic inhibited cell invasion and EMT by targeting PEAK1, lncRNA NORAD acted as a sponge of miR-363-3p and promoted cell invasion and EMT by increasing the expression of PEAK1. In addition, p-ERK expression was detected by Western blotting to observe the effects of lncRNA NORAD, miR-363-3p and PEAK1 on activation of the ERK signaling pathway. Taken together, lncRNA NORAD upregulated the expression of PEAK1 through sponging miR-363-3p, and then activated the ERK signaling pathway, thereby promoting the development of NSCLC.

LncRNA NORAD promotes proliferation, migration and angiogenesis of hepatocellular carcinoma cells through targeting miR-211-5p/FOXD1/VEGF-A axis.

INTRODUCTION AND OBJECTIVES: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death around the world. Despite improvement in the prevention and treatment of HCC, the clinical prognosis is still poor with increasing mortality. Non-coding RNAs play pivotal roles in HCC oncogenesis, but the detailed mechanism is poorly known. Therefore, the functions and interaction of lncRNA NORAD and miR-211-5p in HCC was investigated in this study. METHODS: Quantitative real-time PCR method was used to analyze the expression of NORAD and miR-211-5p in clinical HCC tissues and cultured cell lines. Knockdown of NORAD and overexpression of miR-211-5p were then carried in HCC cells. Moreover, bioinformatics analysis and luciferase report assays were further employed to analyze the interaction between miR-211-5p and NORAD or FOXD1. RESULTS: Increased lncRNA NORAD and decreased miR-211-5p expression were first detected in HCC compared with the peritumorial area. Further studies showed that knockdown of NORAD or overexpression of miR-211-5p impaired the proliferation, migration and angiogenesis of HCC cells. Mechanistically, we found that NORAD functions as a sponge for miR-211-5p. Moreover, it was revealed that decreased miR-211-5p induced the expression of FOXD1 as well as its downstream target VEGF-A, thereby contributes to enhanced angiogenesis of HCC. CONCLUSION: Elevated NORAD works as a sponge for miR-211-5p in HCC, thus release the inhibition effect of the latter on its downstream target FOXD1 and VEGF-A, which finally promotes angiogenesis. These results provide new insights into the interaction between NORAD and miR-211-5p in HCC and their potential usage as targets for the development of novel therapeutics against HCC.

NORAD lentivirus shRNA mitigates fibrosis and inflammatory responses in diabetic cardiomyopathy via the ceRNA network of NORAD/miR-125a-3p/Fyn.

OBJECTIVE: Diabetic cardiomyopathy (DCM) is a serious complication of diabetes, but its pathogenesis is still unclear. This study investigated the mechanism of long noncoding RNA (lncRNA) NORAD in DCM. METHODS: Male leptin receptor-deficient (db/db) mice and leptin control mice (db/ +) were procured. DCM model was established by subcutaneous injection of angiotensin II (ATII) in db/db mice. NORAD lentivirus shRNA or Adv-miR-125a-3p was administered to analyze cardiac function, fibrosis, serum biochemical indexes, inflammation and fibrosis. Primary cardiomyocytes were extracted and transfected with miR-125a-3p mimic. The competing endogenous RNA (ceRNA) network of NORAD/miR-125a-3p/Fyn was verified. The levels of fibrosis- and inflammation-related factors were measured. RESULTS: In db/db mice treated with ATII, the body weight and serum biochemical indexes were increased, while the cardiac function was decreased, and inflammatory cell infiltration and fibrosis were induced. NORAD was upregulated in diabetic and DCM mice. The 4-week intravenous injection of NORAD lentivirus shRNA reduced body weight and serum biochemical indexes, improved cardiac function, and attenuated inflammation and fibrosis in DCM mice. NORAD acted as a sponge to adsorb miR-125a-3p, and miR-125a-3p targeted Fyn. Intravenous injection of miR-125a-3p adenovirus improved cardiac function and fibrosis and reduced inflammatory responses in DCM mice. Co-overexpression of miR-125-3p and Fyn partly reversed the improving effect of miR-125-3p overexpression on cardiac fibrosis in DCM mice. CONCLUSION: NORAD lentivirus shRNA improved cardiac function and fibrosis and reduced inflammatory responses in DCM mice via the ceRNA network of NORAD/miR-125a-3p/Fyn. These findings provide a valuable and promising therapeutic target for the treatment of DCM.