LncRNA NRON promotes tumorigenesis by enhancing MDM2 activity toward tumor suppressor substrates.

The E3 ligase MDM2 promotes tumor growth and progression by inducing ubiquitin-mediated degradation of P53 and other tumor-suppressing proteins. Here, we identified an MDM2-interacting lncRNA NRON, which promotes tumor formation by suppressing both P53-dependent and independent pathways. NRON binds to MDM2 and MDMX (MDM4) via two different stem-loops, respectively, and induces their heterogenous dimerization, thereby enhancing the E3 ligase activity of MDM2 toward its tumor-suppressing substrates, including P53, RB1, and NFAT1. NRON knockdown dramatically inhibits tumor cell growth in vitro and in vivo. More importantly, NRON overexpression promotes oncogenic transformation by inducing anchorage-independent growth in vitro and facilitating tumor formation in immunocompromised mice. Clinically, NRON expression is significantly associated with poor clinical outcome in breast cancer patients. Together, our data uncover a pivotal role of lncRNA that induces malignant transformation of epithelial cells by inhibiting multiple tumor suppressor proteins.

The long non-coding RNA NRON promotes the development of cardiac hypertrophy in the murine heart.

Physiological and pathological cardiovascular processes are tightly regulated by several cellular mechanisms. Non-coding RNAs, including long non-coding RNAs (lncRNAs), represent one important class of molecules involved in regulatory processes within the cell. The lncRNA non-coding repressor of NFAT (NRON) was described as a repressor of the nuclear factor of activated T cells (NFAT) in different in vitro studies. Although the calcineurin/NFAT-signaling pathway is one of the most important pathways in pathological cardiac hypertrophy, a potential regulation of hypertrophy by NRON in vivo has remained unclear. Applying subcellular fractionation and RNA fluorescence in situ hybridization (RNA-FISH), we found that, unlike what is known from T cells, in cardiomyocytes, NRON predominantly localizes to the nucleus. Hypertrophic stimulation in neonatal mouse cardiomyocytes led to a downregulation of NRON, while NRON overexpression led to an increase in expression of hypertrophic markers. To functionally investigate NRON in vivo, we used a mouse model of transverse aortic constriction (TAC)-induced hypertrophy and performed NRON gain- and loss-of-function experiments. Cardiomyocyte-specific NRON overexpression in vivo exacerbated TAC-induced hypertrophy, whereas cardiomyocyte-specific NRON deletion attenuated cardiac hypertrophy in mice. Heart weight, cardiomyocyte cell size, hypertrophic marker gene expression, and left ventricular mass showed a NRON-dependent regulation upon TAC-induced hypertrophy. In line with this, transcriptome profiling revealed an enrichment of anti-hypertrophic signaling pathways upon NRON-knockout during TAC-induced hypertrophy. This set of data refutes the hypothesized anti-hypertrophic role of NRON derived from in vitro studies in non-cardiac cells and suggests a novel regulatory function of NRON in the heart in vivo.

Evaluating lncRNA Expression Patterns during HIV-1 Treatment Interruption.

Lately, the interest in long non-coding RNAs (lncRNAs) as potential drug targets and predictive markers in the context of HIV-1 has peaked, but their in vivo expression and regulation remains largely unexplored. Therefore, the present study examined lncRNA expression patterns during a clinical antiretroviral treatment interruption (ATI) trial. Peripheral blood mononuclear cells were isolated from ten patients at four timepoints: prior to ATI, 7-15 days after stop, at viral rebound and 3 months post antiretroviral therapy re-initiation. RNA was extracted and RT-qPCR on five known HIV-1-related lncRNAs (HEAL, MALAT1, NEAT1, GAS5 and NRON) was performed and correlated with HIV-1 and host marker expression. All lncRNAs correlated stronger with interferon stimulated genes (ISGs) than with HIV-1 reservoir and replication markers. However, one lncRNA, HEAL, showed significant upregulation at viral rebound during ATI compared to baseline and re-initiation of therapy (p = 0.0010 and p = 0.0094, respectively), following a similar viral-load-driven expression pattern to ISGs. In vitro knockdown of HEAL caused a significant reduction in HIV-1 infection levels, validating HEAL's importance for HIV-1 replication. We conclude that the HIV-1-promoting lncRNA HEAL is upregulated at viral rebound during ATI, most likely induced by viral cues.

LncRNA NRON promotes M2 macrophage polarization and alleviates atrial fibrosis through suppressing exosomal miR-23a derived from atrial myocytes.

BACKGROUND/PURPOSE: miR-23a is a pro-hypertrophic miRNA that inhibits M2 macrophage polarization. A previous study demonstrated that lncRNA NRON alleviated atrial fibrosis through suppression of M1 macrophages activated by atrial myocytes. This study aimed to determine whether NRON promotes M2 macrophage polarization and alleviates atrial fibrosis through suppressing exosomal miR-23a derived from atrial myocytes. METHODS: Mouse atrial myocytes were transfected with the NRON overexpression vector or empty vector, followed by Ang II treatment. Exosomes were isolated from the treated atrial myocytes and then co-cultured with RAW264.7 macrophages. The culture medium from RAW264.7 macrophages treated as described above was added to mouse atrial fibroblasts for incubation. RESULTS: We found that exosomes derived from Ang II-treated atrial myocytes inhibited M2 macrophage polarization by transferring miR-23a. NFATc3 could directly bind to the miR-23a promoter. Overexpression of NRON inhibited the expression of miR-23a by inhibiting NFATc3 nuclear transport in Ang II-treated atrial myocytes, resulting in a decrease in the level of miR-23a in atrial myocyte-derived exosomes. Meanwhile, exosomes derived from NRON-overexpressing atrial myocytes promoted M2 macrophage polarization and inhibited expression of fibrosis markers in atrial fibroblasts. CONCLUSION: NRON promotes M2 macrophage polarization and alleviates atrial fibrosis through suppressing exosomal miR-23a derived from atrial myocytes.

LncRNA NRON alleviates atrial fibrosis via promoting NFATc3 phosphorylation.

The aim of this study was to explore the role of NRON in the atrial fibrosis. The expression of NRON in atrial tissue was detected using qRT-PCR. The protein levels of collagen I, collagen III, NFATc3 and p-NFATc3 were determined by western blot. Immunohistochemistry assay were performed to observe expression and distribution of collagen I in atrial tissues. The atrial fibroblasts were authenticated by vimentin/troponin immunofluorescence staining. Fibroblast proliferation was detected by CCK-8 assay. The morphological changes of cardiac tissue were observed by HE staining. Myocardial fibrosis was detected by masson staining. NRON expression was significantly downregulated in atrial tissues of AF. NRON suppressed fibroblast proliferation; expression of collagen I and collagen III; activation of NFATc3 and nucleu import. NRON promoted p-NFATc3 expression and alleviated atrial fibrosis in vivo. Our data indicated that NRON alleviates atrial fibrosis via promoting NFATc3 phosphorylation.

Circulating long non-coding RNAs NRON and MHRT as novel predictive biomarkers of heart failure.

This study sought to evaluate the potential of circulating long non-coding RNAs (lncRNAs) as biomarkers for heart failure (HF). We measured the circulating levels of 13 individual lncRNAs which are known to be relevant to cardiovascular disease in the plasma samples from 72 HF patients and 60 non-HF control participants using real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) methods. We found that out of the 13 lncRNAs tested, non-coding repressor of NFAT (NRON) and myosin heavy-chain-associated RNA transcripts (MHRT) had significantly higher plasma levels in HF than in non-HF subjects: 3.17 ± 0.30 versus 1.0 ± 0.07 for NRON (P < 0.0001) and 1.66 ± 0.14 versus 1.0 ± 0.12 for MHRT (P < 0.0001). The area under the ROC curve was 0.865 for NRON and 0.702 for MHRT. Univariate and multivariate analyses identified NRON and MHRT as independent predictors for HF. Spearman's rank correlation analysis showed that NRON was negatively correlated with HDL and positively correlated with LDH, whereas MHRT was positively correlated with AST and LDH. Hence, elevation of circulating NRON and MHRT predicts HF and may be considered as novel biomarkers of HF.

Involvement of NRON and TUG1 long noncoding RNAs in inflammation and the pathogenesis of EAE.

There is growing evidence that the long noncoding RNAs (lncRNAs) contribute to the pathogenesis of various neurodegenerative diseases such as multiple sclerosis (MS). The role of lncRNAs nuclear repressor of NFAT (NRON) and Taurine up-regulated 1 (TUG1) in the inflammatory processes occurring in the experimental autoimmune encephalomyelitis (EAE) model of MS is yet to be investigated. Transcript levels of NRON and TUG1 in acute and chronic phases of EAE and cultured macrophages as well as the correlation between NRON and TUG1 expression with inflammatory cytokines, were evaluated in this study. EAE experimental model was induced in female C57BL/6 mice with subcutaneous injection of MOG35-55/CFA. Mice were scored for 28 days and then sacrificed. The expression of lncRNAs TUG1 and NRON in lumbar spinal cords, activated and controlled macrophages as well as the expression of IL-1, IL-6, and CDe-3 inflammatory cytokines, were assayed by real-time RT-PCR. The lncRNAs TUG1 and NRON were significantly down-regulated in lumbar spinal cords tissues in the acute phase of EAE compared to the control group. TUG1 and NRON were significantly down-regulated in macrophages treated with 10 ng lipopolysaccharide (LPS) compared to the control macrophages. A negative correlation was identified between NRON and TUG1 expression and IL-1, IL-6, and CDe-3 inflammatory cytokines. The present study demonstrates the dysregulation of lncRNAs TUG1 and NRON in spinal cord tissue lesions of EAE and activated macrophages, pointing to their potential role in the pathogenesis of EAE.

LncRNA NRON negatively regulates cisplatin-induced cell apoptosis via downregulating miR-31 in esophageal squamous cell carcinomas.

LncRNA non-coding repressor of NFAT (NRON) can promote bladder cancer and suppress liver cancer, while its role in esophageal squamous cell carcinoma (ESCC) is unknown. We analyzed its involvement in ESCC. NRON and miR-31 expression in plasma before and after cisplatin treatment was detected using RT-qPCR. The correlation between NRON and miR-31 was analyzed by linear regression. Expression of NRON and miR-31 in ESCC cells was also analyzed using RT-qPCR. Overexpression of NRON and miR-31 was achieved in ESCC cells to explore their interaction. Cell apoptosis induced by cisplatin was studied using cell apoptosis assay. NRON was highly expressed in ESCC and further upregulated after cisplatin treatment. MiR-31 was downregulated in ESCC and inversely correlated with NRON. In ESCC cells, NRON overexpression decreased miR-31 expression, while miR-31 failed to alter NRON expression. Cisplatin treatment promoted NRON expression and inhibited miR-31 expression. Under cisplatin treatment, cell apoptosis was inhibited after NRON overexpression and increased after miR-31 overexpression. Moreover, NRON inhibited the effect of miR-31 on cell apoptosis. NRON might promote the development of cisplatin resistance via downregulating miR-31 in ESCC.

Bioactive glass nanoparticles inhibit osteoclast differentiation and osteoporotic bone loss by activating lncRNA NRON expression in the extracellular vesicles derived from bone marrow mesenchymal stem cells.

Bioactive glass nanoparticles (BGN) have attracted increasing attention for their use in bone tissue repair owing to their special osteogenic activity; however, the underlying molecular mechanism remains unclear. In this study, we report a new mechanism by which BGN regulate bone loss in an osteoporosis mouse model. We found that BGN induced the expression of extracellular vesicles secreted by bone marrow mesenchymal stem cells (BGN + BMSC-EVs), which can inhibit osteoclast differentiation in vitro. Furthermore, our results showed that BGN + BMSC-EVs were rich in the long non-coding RNA NRON, which can inhibit the nuclear translocation of NFATc1 by binding to the nuclear factor of activated T cells transcription factors, thereby inhibiting osteoclast differentiation. We validated the function and biological safety of BGN + BMSC-EVs in an ovariectomized mouse model of osteoporosis. The results of in vivo studies showed that BGN + BMSC-EVs could alleviate bone loss in osteoporotic mice, restore the mechanical properties of mouse femurs, and improve the biochemical indicators in the peripheral blood for bone metabolism in mice, with little to no acute, systemic toxicity. This study may provide a new explanation for the role of BGN in inhibiting osteoclast differentiation and relieving bone loss; additionally, the study findings reveal a promising strategy for the treatment of bone resorption disorders.

Long Non-Coding RNA NRON promotes Tumor Proliferation by regulating ALKBH5 and Nanog in Gastric Cancer.

Long non-coding RNAs (lncRNAs) act as tumor suppressors or oncogenes in tumor development and progression. In this study, we explored the expression and biological role of lncRNA NRON in gastric cancer (GC). We observed that lncNRON was upregulated in GC tissues and cell lines, and high lncNRON expression was associated with malignant features and poor prognosis in GC patients. LncNRON was found to promote the proliferation and tumorigenicity of GC cells. Mechanistically, lncNRON exerted its oncogenic functions by binding to the N6-methyladenosine eraser ALKHB5 and mediating Nanog mRNA decay. In conclusion, our results suggest that lncNRON serves as an oncogenic lncRNA in GC and thus may be a promising prognostic factor and potential therapeutic target for GC patients.

Long non coding RNA NRON inhibited breast cancer development through regulating miR-302b/SRSF2 axis.

AIMS: Long noncoding RNA NRON has been investigated in various tumors, such as hepatocellular carcinoma. However, the role of lncRNA NRON in breast cancer remains unclear. The aim of this study was to explore the function and mechanism of lncRNA NRON in breast cancer. MATERIALS AND METHODS: Overexpression and knockdown vectors were constructed. Proliferation and invasion were measured to evaluate the function of lncRNA NRON. A dual-luciferase reporter assay was utilized to analyze the potential binding target of lncRNA NRON. A rescue experiment was performed to verify the relationship between lncRNA NRON and SRSF2. RESULTS: Our results showed that the expression of lncRNA NRON was significantly downregulated in breast cancer tissues. Overexpression of lncRNA NRON significantly inhibited proliferation and invasion in breast cancer cell lines. Knockdown of lncRNA NRON promoted breast cancer development. We also provided evidence that lncRNA NRON negatively regulated miR-302b. Moreover, we identified SRSF2 as a downstream target of miR-302b. CONCLUSION: Overall, we performed a comprehensive analysis to indicate that the lncRNA NRON/miR-302b/SRSF2 axis plays an important role in breast cancer. Our study is the first to prove that lncRNA NRON functions as a tumor suppressor in breast cancer.

LncRNA NRON promotes the proliferation, metastasis and EMT process in bladder cancer.

Background: Bladder cancer (BC) is one of the most common malignancies world-wide with high morbidity and mortality. Long noncoding RNAs (lncRNAs) are thought to play a critical role in cancer development. LncRNA NRON, a repressor of activated T-cell nuclear factor (NFAT), has been shown to be dysregulated in many cancer types. However, the clinical significance and molecular mechanism of NRON in bladder cancer is still unknown. Methods: The expression levels of NRON in BC tissues and cell lines were tested by RT-qPCR. Survival analysis was performed to detect the correlation between NRON expression and clinical outcomes in patients with BC. The biological role of NRON in BC cells proliferation and metastasis was examined in vitro and in vivo. Results: The expression of NRON was significantly upregulated in BC specimens and cell lines compared with paired adjacent normal tissues and normal cell lines. The upregulation of NRON in bladder cancer patients was significantly associated with the depth of bladder tumor invasion and poor prognosis. Knockdown of NRON inhibited BC cells proliferation, migration, invasion and tumorigenicity. Furthermore, NRON promoted epithelial-mesenchymal transition (EMT) progression, and NRON-induced EZH2 expression contributed to this process. Conclusion: In conclusion, our results suggested that NRON acted as an oncogene and tumor biomarker for BC.

LncRNA NRON down-regulates lncRNA snaR and inhibits cancer cell proliferation in TNBC.

NRON mediates the degradation of tat protein to participate in HIV-1 infection. Interestingly, our study observed the down-regulation of NRON in triple-negative breast cancer (TNBC) tissues compared with paired adjacent healthy tissues. In contrast, lncRNA snaR was up-regulated in TNBC tissues and was inversely correlated with NRON. Expression levels of snaR increased, while expression levels of NRON decreased along with the increase of clinical stages. The snaR overexpression resulted in promoted cancer cell proliferation but did not significantly affect NRON expression. NRON overexpression inhibited cancer cell proliferation and down-regulated snaR. The snaR overexpression reduced the effects of NRON overexpression. We therefore conclude that NRON may down-regulate lncRNA snaR to inhibit cancer cell proliferation in TNBC.

LncRNA NRON alleviates atrial fibrosis through suppression of M1 macrophages activated by atrial myocytes.

The aim of the present study was to explore the role of long non-coding RNA (lncRNA) non-coding repressor of NFAT (NRON) in the atrial fibrosis and to explore whether its underlying mechanism was associated with macrophage polarization. Enzyme-linked immunosorbent assay (ELISA) analysis of pro-inflammatory cytokines revealed that NRON overexpression suppressed, whereas NRON silencing facilitated the angiotensin II (Ang II)-induced inflammatory response in primary cultured atrial myocytes. The chromatin immunoprecipitation (ChIP) results showed that nuclear factor of activated T cell 3 (NFATc3) was recruited to the promoter region of interleukin (IL) 12 (IL-12) in atrial myocytes. Further data showed that NRON overexpression suppressed, whereas NRON silencing further promoted the Ang II-induced NFATc3 nuclear transport and IL-12 expression in atrial myocytes. Moreover, RAW264.7 macrophages were incubated with the conditioned medium from the Ang II-treated atrial myocytes transfected with NRON and IL-12 overexpression vectors. IL-12 overexpression abrogated the NRON overexpression-mediated inhibition of RAW264.7 macrophage polarization to the M1-like phenotype. Additionally, mouse atrial fibroblasts were incubated with the culture medium from RAW264.7 macrophages treated as described above. IL-12 overexpression rescued the NRON overexpression-inhibited protein levels of fibrosis markers Collagen I/III in mouse atrial fibroblasts. Collectively, our data indicate that lncRNA NRON alleviates atrial fibrosis through suppression of M1 macrophages activated by atrial myocytes.

The kinase LRRK2 is differently expressed in chronic rhinosinusitis with and without nasal polyps.

BACKGROUND: Chronic rhinosinusitis (CRS), commonly divided into CRS with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP) is an inflammatory disease which mechanism remain unclear. Leucine-rich repeat kinase 2 (LRRK2) has been proved to be a negative regulator of inflammation response while its role in pathogenesis of CRS has yet to be revealed. This research study was designed to investigate the relationship between the expression level and biologic role of LRRK2 in CRS. METHODS: Expression of LRRK2 mRNA and noncoding repressor of NFAT (NRON) were examined by qRT-PCR. Protein levels of LRRK2 were performed by western blot and immunohistochemistry. Nuclear factor of activated T cells (NFAT) nuclear translocation was analyzed by immunohistochemistry. Additionally, LRRK2 mRNA and NRON expression in response to specific inflammatory stimulation was measured in human nasal epithelia cells (HNECs). RESULTS: The expression of LRRK2 was increased in CRSsNP patients (p  <  0.05) and positively correlated with the expression levels of CD3 and Charot-Leyden crystal. Meanwhile, the NRON expression level is much lower in CRSsNP patients compared to both the control group and CRSwNP group (p  <  0.05). Marked enhanced NFAT nuclear localization was observed in CRSwNP groups compared with the CRSsNP and control group (p  <  0.0001). And the over-expression of LRRK2 was significantly regulated by lipopolysaccharide (LPS) in HNECs (p  <  0.05). Moreover, IL-17A can increase LRRK2 expression and suppress NRON expression in vitro and dexamethasone can rescue the NRON inhibition. CONCLUSION: LRRK2 and NRON may play different role in CRSsNP and CRSwNP. The molecular mechanisms identified here may aid in the design of novel therapeutic strategies to improve clinical outcomes.

Long non-coding RNA NRON is downregulated in HCC and suppresses tumour cell proliferation and metastasis.

Dysregulation of long non-coding RNAs is a newly identified mechanism for tumour progression. Previous studies have suggested that the nuclear factor of activated T cells (NFAT) gene plays a very important role in cancer growth and metastasis. However, lncNRON is a newly identified repressor of NFAT, and its function is largely unknown, especially in hepatocellular carcinoma (HCC). Therefore, the expression levels of lncNRON in 215 pairs of HCC tissue were evaluated by qRT-PCR, and its relationship to clinicopathological parameters, recurrence, and survival was analysed. Furthermore, stably overexpressing lncNRON cell lines were constructed and evaluated for cell phenotype. Finally, we detected epithelial-to-mesenchymal transition (EMT) proteins to determine the underlying mechanism involved in lncNRON function. We observed that lncNRON was downregulated in HCC tumour tissues; low lncNRON expression was associated with poor tumour differentiation and the presence of vascular tumour thrombus, which tended to result in poor clinical outcomes, as demonstrated by the recurrence rate and survival curves. Functional analysis showed that lncNRON overexpression impaired colony formation and cell viability and inhibited cell migration and invasion. A study using tumour-bearing mice showed that lncNRON markedly limited tumour growth and lung metastasis in vivo. Importantly, western blot analysis revealed that the expression of the EMT-related epithelial marker, E-cadherin, increased, whereas the expression of mesenchymal markers N-cadherin, snail, and vimentin was attenuated by lncNRON overexpression in HCC cells. Therefore, lower lncNRON expression indicates a poorer clinical outcome in HCC. LncNRON overexpression can suppress HCC growth and metastasis via inhibiting the EMT, and lncNRON may function as a new HCC prognostic marker.

Z Probe, An Efficient Tool for Characterizing Long Non-Coding RNA in FFPE Tissues.

Formalin-fixed paraffin embedded (FFPE) tissues are a valuable resource for biomarker discovery in order to understand the etiology of different cancers and many other diseases. Proteins are the biomarkers of interest with respect to FFPE tissues as RNA degradation is the major challenge in these tissue samples. Recently, non-protein coding transcripts, long non-coding RNAs (lncRNAs), have gained significant attention due to their important biological actions and potential involvement in cancer. RNA sequencing (RNA-seq) or quantitative reverse transcription-polymerase chain reaction (qRT-PCR) are the only validated methods to evaluate and study lncRNA expression and neither of them provides visual representation as immunohistochemistry (IHC) provides for proteins. We have standardized and are reporting a sensitive Z probe based in situ hybridization method to visually identify and quantify lncRNA in FFPE tissues. This assay is highly sensitive and identifies transcripts visible within different cell types and tumors. We have detected a scarcely expressed tumor suppressor lncRNA NRON (non-coding repressor of nuclear factor of activated T-cells (NFAT)), a moderately expressed oncogenic lncRNA UCA1 (urothelial cancer associated 1), and a highly studied and expressed lncRNA MALAT1 (metastasis associated lung adenocarcinoma transcript 1) in different cancers. High MALAT1 staining was found in colorectal, breast and pancreatic cancer. Additionally, we have observed an increase in MALAT1 expression in different stages of colorectal cancer.

Leucine-Rich Repeat Kinase 2 Controls the Ca2+/Nuclear Factor of Activated T Cells/IL-2 Pathway during Aspergillus Non-Canonical Autophagy in Dendritic Cells.

The Parkinson's disease-associated protein, Leucine-rich repeat kinase 2 (LRRK2), a known negative regulator of nuclear factor of activated T cells (NFAT), is expressed in myeloid cells such as macrophages and dendritic cells (DCs) and is involved in the host immune response against pathogens. Since, the Ca2+/NFAT/IL-2 axis has been previously found to regulate DC response to the fungus Aspergillus, we have investigated the role played by the kinase LRRK2 during fungal infection. Mechanistically, we found that in the early stages of the non-canonical autophagic response of DCs to the germinated spores of Aspergillus, LRRK2 undergoes progressive degradation and regulates NFAT translocation from the cytoplasm to the nucleus. Our results shed new light on the complexity of the Ca2+/NFAT/IL-2 pathway, where LRRK2 plays a role in controlling the immune response of DCs to Aspergillus.