Long non‐coding RNA TNRC6C‐AS1 promotes methylation of STK4 to inhibit thyroid carcinoma cell apoptosis and autophagy via Hippo signalling pathway

The role of long non‐coding RNAs (lncRNAs) in thyroid carcinoma (TC), the most frequent endocrine malignancy, has been extensively examined. This study investigated effect of interaction among lncRNA TNRC6C‐AS1, serine/threonine‐protein kinase 4 (STK4) and Hippo signalling pathway on TC. Initially, lncRNA TNRC6C‐AS1 expression in TC tissues was detected. To explore roles of lncRNA TNRC6C‐AS1, STK4 and Hippo signalling pathway in TC progression, their expressions were altered. Interaction between lncRNA TNRC6C‐AS1 and STK4, STK4 promoter methylation, or Hippo signalling pathway was verified. After that, a series of experiments were employed to evaluate in vitro ability of apoptosis, proliferation and autophagy of TC cells and in vivo tumorigenicity, and tumour growth of TC cells. lncRNA TNRC6C‐AS1 was highly expressed while STK4 was poorly expressed in TC tissues. LncRNA TNRC6C‐AS1 promoted the STK4 methylation and down‐regulated STK4 expression, which further activated the Hippo signalling pathway. STK4 silencing was observed to promote the proliferation ability of TC cells, inhibit the apoptosis and autophagy abilities, as well as enhance the tumorigenicity and tumour growth. Moreover, the in vitro proliferation ability as well as the in vivo tumorigenicity and tumour growth of TC cells were inhibited after the blockade of Hippo signalling pathway, while the apoptosis and autophagy abilities were promoted. The results demonstrate that the lncRNA TNRC6C‐AS1 increases STK4 promoter methylation to down‐regulate STK4 expression, thereby promoting the development of TC through activation of Hippo signalling pathway. It highlights that lncRNA TNRC6C‐AS1 may be a novel therapeutic target for the treatment of TC.     

lncRNA NR2F1‐AS1 promotes breast cancer angiogenesis through activating IGF‐1/IGF‐1R/ERK pathway

Long non‐coding RNAs (lncRNAs) take various effects in cancer mostly through sponging with microRNAs (miRNAs). lncRNA NR2F1‐AS1 is found to promote tumour progression in hepatocellular carcinoma, endometrial cancer and thyroid cancer. However, the role of lncRNA NR2F1‐AS1 in breast cancer angiogenesis remains unknown. In this study, we found lncRNA NR2F1‐AS1 was positively related with CD31 and CD34 in breast cancer through Pearson's correlation analysis, while lncRNA NR2F1‐AS1 transfection promoted human umbilical vascular endothelial cell (HUVEC) tube formation. In breast cancer cells, lncRNA NR2F1‐AS1 enhanced the HUVEC proliferation, tube formation and migration ability through tumour‐conditioned medium (TCM). In zebrafish model, lncRNA NR2F1‐AS1 increased the breast cancer cell‐related neo‐vasculature and subsequently promoted the breast cancer cell metastasis. In mouse model, lncRNA NR2F1‐AS1 promoted the tumour vessel formation, increased the micro vessel density (MVD) and then induced the growth of primary tumour. Mechanically, lncRNA NR2F1‐AS1 increased insulin‐like growth factor‐1 (IGF‐1) expression through sponging miRNA‐338‐3p in breast cancer cells and then activated the receptor of IGF‐1 (IGF‐1R) and extracellular signal‐regulated kinase (ERK) pathway in HUVECs. These results indicated that lncRNA NR2F1‐AS1 could promote breast cancer angiogenesis through IGF‐1/IGF‐1R/ERK pathway.     

Down‐regulated lncRNA SLC25A5‐AS1 facilitates cell growth and inhibits apoptosis via miR‐19a‐3p/PTEN/PI3K/AKT signalling pathway in gastric cancer

Mounting evidence has illustrated the vital roles of long non‐coding RNAs (lncRNAs in gastric cancer (GC). Nevertheless, the majority of their roles and mechanisms in GC are still largely unknown. In this study, we investigate the roles of lncRNA SLC25A5‐AS1 on tumourigenesis and explore its potential mechanisms in GC. The results showed that the expressions of SLC25A5‐AS1 in GC were significantly lower than that of adjacent normal tissues, which were significantly associated with tumour size, TNM stage and lymph node metastasis. Moreover, SLC25A5‐AS1 could inhibit GC cell proliferation, induce G1/G1 cell cycle arrest and cell apoptosis in vitro, as well as GC growth in vivo. Dual‐luciferase reporter assay confirmed the direct interaction between SLC25A5‐AS1 and miR‐19a‐3p, rescue experiment showed that co‐transfection miR‐19a‐3p mimics and pcDNA‐SLC25A5‐AS1 could partially restore the ability of GC cell proliferation and the inhibition of cell apoptosis. The mechanism analyses further found that SLC25A5‐AS1 might act as a competing endogenous RNAs (ceRNA), which was involved in the derepression of PTEN expression, a target gene of miR‐19a‐3p, and regulate malignant phenotype via PI3K/AKT signalling pathway in GC. Taken together, this study indicated that SLC25A5‐AS1 was down‐regulated in GC and functioned as a suppressor in the progression of GC. Moreover, it could act as a ceRNA to regulate cellular behaviours via miR‐19a‐3p/PTEN/PI3K/AKT signalling pathway. Thus, SLC25A5‐AS1 might be served as a potential target for cancer therapeutics in GC.     

LncRNA ABHD11‐AS1 promotes the development of endometrial carcinoma by targeting cyclin D1

To investigate the expression, role and mechanism of action of long non‐coding RNA (lncRNA) ABHD11‐AS1 in endometrial carcinoma. The expression of lncRNA ABHD11‐AS1 was quantified by qRT‐PCR in human endometrial carcinoma (n = 89) and normal endometrial tissues (n = 27). LncRNA ABHD11‐AS1 was stably overexpressed or knocked‐down in endometrial carcinoma cell lines to examine the cellular phenotype and expression of related molecules. Compared to normal endometrial tissue, lncRNA ABHD11‐AS1 was significantly overexpressed in endometrial carcinoma. Overexpression of lncRNA ABHD11‐AS1 promoted the proliferation, G1‐S progression, invasion and migration of endometrial cancer cells; inhibited apoptosis; up‐regulated cyclin D1, CDK1, CDK2, CDK4, Bcl‐xl and VEGFA; and down‐regulated p16, while ABHD11‐AS1 down‐regulation has the opposite effect. RNA pull down demonstrated that lncRNA ABHD11‐AS1 binds directly to cyclin D1. Knockdown of cyclin D1 can reverse the effect of ABHD11‐AS1. Overexpression of lncRNA ABHD11‐AS1 increased the tumorigenicity and up‐regulated cyclin D1 in an in vivo model of endometrial cancer in nude mice. LncRNA ABHD11‐AS1 functions as an oncogene to promote cell proliferation and invasion in endometrial carcinoma by positively targeting cyclin D1.     

LncRNA‐DANCR contributes to lung adenocarcinoma progression by sponging miR‐496 to modulate mTOR expression

Long non‐coding RNAs (lncRNAs) have emerged as new and important regulators of pathological processes including tumour development. In this study, we demonstrated that differentiation antagonizing non‐protein coding RNA (DANCR) was up‐regulated in lung adenocarcinoma (ADC) and that the knockdown of DANCR inhibited tumour cell proliferation, migration and invasion and restored cell apoptosis rescued; cotransfection with a miR‐496 inhibitor reversed these effects. Luciferase reporter assays showed that miR‐496 directly modulated DANCR; additionally, we used RNA‐binding protein immunoprecipitation (RIP) and RNA pull‐down assays to further confirm that the suppression of DANCR by miR‐496 was RISC‐dependent. Our study also indicated that mTOR was a target of miR‐496 and that DANCR could modulate the expression levels of mTOR by working as a competing endogenous RNA (ceRNA). Furthermore, the knockdown of DANCR reduced tumour volumes in vivo compared with those of the control group. In conclusion, this study showed that DANCR might be an oncogenic lncRNA that regulates mTOR expression through directly binding to miR‐496. DANCR may be regarded as a biomarker or therapeutic target for ADC.     

ISG12a and its interaction partner NR4A1 are involved in TRAIL‐induced apoptosis in hepatoma cells

Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) can induce apoptosis in cancer cells while sparing normal cells, thereby leading to the development of TRAIL receptor agonists for cancer treatment. However, these agonist‐based therapeutics exhibit little clinical benefits due to the lack of biomarkers to predict whether patients are responsive to the treatment, as well as determine the resistance of cancer cells to TRAIL‐based agonists. Our previous study has demonstrated that ISG12a enhances TRAIL‐induced apoptosis and might serve as a biomarker to predict the TRAIL response. The downstream mechanism by which ISG12a augments TRAIL‐induced apoptosis remains to be elucidated. In this study, we found that ISG12a was localized in the mitochondria and nucleus and augmented TRAIL‐induced apoptosis through intrinsic apoptotic pathway. In addition, ISG12a interacted with NR4A1 and promoted its nuclear‐to‐cytoplasm translocation. Upon translocate to cytoplasm, NR4A1 targeted mitochondria and induced Bcl2 conformational change, thereby exposing its BH3 domain. Moreover, TRAIL treatment can induce NR4A1 expression through the activation of NF‐κB in TRAIL‐resistant Huh7 hepatoma cells. Knockdown of NR4A1 could overcome TRAIL resistance. However, in TRAIL‐sensitive LH86 liver cancer cells, TRAIL activated the Jun N‐terminal kinases signalling pathway. Overall, these results showed that both ISG12a and its interaction partner NR4A1 are involved in TRAIL‐mediated apoptosis in hepatoma cells.     

Long non‐coding RNA LINC01225 promotes proliferation,invasion and migration of gastric cancer via Wnt/β‐catenin signalling pathway

Emerging evidence has classified the aberrant expression of long non‐coding RNAs (lncRNAs) as a basic signature of various malignancies including gastric cancer (GC). LINC01225 has been shown to act as a hepatocellular carcinoma‐related gene, with its expression pattern and biological function not clarified in GC. Here, we verified that LINC01225 was up‐regulated in tumour tissues and plasma of GC. Analysis with clinicopathological information suggested that up‐regulation of LINC01225 was associated with advanced disease and poorer overall survival. Receiver operating characteristic (ROC) analysis showed that plasma LINC01225 had a moderate accuracy for diagnosis of GC. In addition, knockdown of LINC01225 led to retardation of cell proliferation, invasion and migration, and overexpression of LINC01225 showed the opposite effects. Mechanistic investigations showed that LINC01225 silencing inhibited epithelial‐mesenchymal transition (EMT) process and attenuated Wnt/β‐catenin signalling of GC. Furthermore, ectopic expression of Wnt1 or suppression of GSK‐3β abolished the si‐LINC01225‐mediated suppression against EMT, thereby promoting cell proliferation, invasion and migration of GC. In conclusion, LINC01225 promotes the progression of GC through Wnt/β‐catenin signalling pathway, and it may serve as a potential target or strategy for diagnosis or treatment of GC.     

AFAP1‐AS1: A novel oncogenic long non‐coding RNA in human cancers

Long non‐coding RNAs (lncRNAs), a group of non‐protein‐coding RNAs with more than 200 nucleotides in length, are involved in multiple biological processes, such as the proliferation, apoptosis, migration and invasion. Moreover, numerous studies have shown that lncRNAs play important roles as oncogenes or tumour suppressor genes in human cancers. In this paper, we concentrate on actin filament‐associated protein 1‐antisense RNA 1 (AFAP1‐AS1), a well‐known long non‐coding RNA that is overexpressed in various tumour tissues and cell lines, including oesophageal cancer, pancreatic ductal adenocarcinoma, nasopharyngeal carcinoma, lung cancer, hepatocellular carcinoma, ovarian cancer, colorectal cancer, biliary tract cancer and gastric cancer. Moreover, high expression of AFAP1‐AS1 was associated with the clinicopathological features and cancer progression. In this review, we sum up the current studies on the characteristics of AFAP1‐AS1 in the biological function and mechanism of human cancers.     

LncRNA NR2F2‐AS1 promotes tumourigenesis through modulating BMI1 expression by targeting miR‐320b in non‐small cell lung cancer

Recently, long noncoding RNAs (lncRNAs) are attracting wide attention in the field of cancer research because of its important role in cancer diagnosis and prognosis. But studies on the biological effects and relevant mechanisms of lncRNAs in non‐small cell lung cancer (NSCLC) remain few and need to be enriched. Our study discussed the expression and biological effects of LncRNA NR2F2‐AS1, and further explored its possible molecular mechanisms. As a result, elevated expression of NR2F2‐AS1 was detected in NSCLC tissues and cells and was remarkably associated with the tumor, node, metastasis (TNM) stage and the status of lymphatic metastasis of patients. Down‐regulated NR2F2‐AS1 contributed to the promotion of cell apoptosis and the inhibition of cell proliferation and invasion in A549 and SPC‐A‐1 cells in vivo and vitro. Through bioinformatics analysis, NR2F2‐AS1 functions as a ceRNA directly binding to miR‐320b, BMI1 was a direct target of miR‐320b. Combined with the following cellular experiments, the data showed that NR2F2‐AS1 may influence the NSCLC cell proliferation, invasion and apoptosis through regulating miR‐320b targeting BMI1.     

CTCF regulates the FoxO signaling pathway to affect the progression of prostate cancer

The present research focuses on the influence of CCCTC‐binding factor (CTCF) on prostate cancer (PC) via the regulation of the FoxO signalling pathway. A bioinformatics analysis was conducted to screen out target genes for CTCF in LNCaP cells and to enrich the relevant pathways in LNCaP cells. It was found that the FoxO pathway was enriched according to the ChIP‐seq results of CTCF. The expression of CTCF, pFoxO1a, FoxO1a, pFoxO3a and FoxO3a was tested by RT‐qPCR and Western blot. Inhibition of CTCF could lead to the up‐regulation of the FoxO signalling pathway. The rates of cell proliferation, cell invasion and apoptosis were examined by MTT assay, cell invasion assay and flow cytometry under different interference conditions. Down‐regulation of CTCF could suppress cell proliferation, cell invasion and facilitate cell apoptosis. Lastly, the effect of CTCF on tumour growth was determined in nude mice. Inhibition of CTCF regulated the FoxO signalling pathway, which retarded tumour growth in vivo. In conclusion, CTCF regulates the FoxO signalling pathway to affect the progress of PC.     

Long non‐coding RNA SNAI3‐AS1 promotes the proliferation and metastasis of hepatocellular carcinoma by regulating the UPF1/Smad7 signalling pathway

Emerging evidence has indicated that deregulation of long non‐coding RNAs (lncRNAs) can contribute to the progression of human cancers, including hepatocellular carcinoma (HCC). However, the role and exact mechanism of most lncRNAs in tumours remains largely unknown. In the current study, we found a novel long non‐coding RNA termed SNAI3‐AS1 which was generally up‐regulated in HCC tissues compared with normal control. Higher expression of SNAI3‐AS1 was significantly correlated with shorter overall survival of HCC patients. Knockdown of SNAI3‐AS1 inhibited the proliferation and metastasis of HCC cells in vitro, whereas overexpression of SNAI3‐AS1 promoted the proliferation and metastasis of HCC cells. Further investigations showed that SNAI3‐AS1 could affect HCC tumorigenesis by binding up‐frameshift protein 1 (UPF1), regulating Smad7 expression and activating TGF‐β/Smad pathway. Functionally, SNAI3‐AS1 promoted HCC growth and metastasis by inducing tumour epithelial to mesenchymal transition (EMT). Taken together, these findings showed that SNAI3‐AS1 promotes the progression of HCC by regulating the UPF1 and activating TGF‐β/Smad pathway.     

Long non‐coding RNA F11‐AS1 inhibits HBV‐related hepatocellular carcinoma progression by regulating NR1I3 via binding to microRNA‐211‐5p

Long non‐coding RNAs (lncRNAs) could regulate growth and metastasis of hepatocellular carcinoma (HCC). In this study, we aimed to investigate the mechanism of lncRNA F11‐AS1 in hepatitis B virus (HBV)–related HCC. The relation of lncRNA F11‐AS1 expression in HBV‐related HCC tissues to prognosis was analysed in silico. Stably HBV‐expressing HepG2.2.15 cells were established to explore the regulation of lncRNA F11‐AS1 by HBx protein, as well as to study the effects of overexpressed lncRNA F11‐AS1 on proliferation, migration, invasion and apoptosis in vitro. Subsequently, the underlying interactions and roles of lncRNA F11‐AS1/miR‐211‐5p/NR1I3 axis in HBV‐related HCC were investigated. Additionally, the influence of lncRNA F11‐AS1 and miR‐211‐5p on tumour growth and metastasis capacity of HepG2.2.15 cells were studied on tumour‐bearing nude mice. Poor expression of lncRNA F11‐AS1 was correlated with poor prognosis in patients with HBV‐related HCC, and its down‐regulation was caused by the HBx protein. lncRNA F11‐AS1 was proved to up‐regulate the NR1I3 expression by binding to miR‐211‐5p. Overexpression of lncRNA F11‐AS1 reduced the proliferation, migration and invasion, yet induced apoptosis of HepG2.2.15 cells in vitro, which could be abolished by overexpression of miR‐211‐5p. Additionally, either lncRNA F11‐AS1 overexpression or miR‐211‐5p inhibition attenuated the tumour growth and metastasis capacity of HepG2.2.15 cells in vivo. Collectively, lncRNA F11‐AS1 acted as a modulator of miR‐211‐5p to positively regulate the expression of NR1I3, and the lncRNA F11‐AS1/miR‐211‐5p/NR1I3 axis participated in HBV‐related HCC progression via interference with the cellular physiology of HCC.     

The pro‐inflammatory effect of NR4A3 in osteoarthritis

NR4A3 is a member of nuclear receptor subfamily 4, which is an important regulator of cellular function and inflammation. In this study, high expression of NR4A3 in human osteoarthritis (OA) cartilage was firstly observed. To explore the relationship between NR4A3 and OA, we used a lentivirus overexpression system to simulate its high expression and study its role in OA. Additionally, siRNA‐mediated knockdown of NR4A3 was used to confirm the findings of overexpression experiments. The results showed the stimulatory effect of IL‐1β on cartilage matrix‐degrading enzyme expression such as MMP‐3, 9, INOS and COX‐2 was enhanced in NR4A3‐overexpressed chondrocytes and decreased in NR4A3‐knockdown chondrocytes at both mRNA and protein levels, while IL‐1β‐induced chondrocyte‐specific gene (collagen 2 and SOX‐9) degradation was only regulated by NR4A3 at protein level. Furthermore, overexpression of NR4A3 would also enhance EBSS‐induced chondrocytes apoptosis, while knockdown of NR4A3 decreased apoptotic level after EBSS treatment. A pathway study indicated that IL‐1β‐induced NF‐κB activation was enhanced by NR4A3 overexpression and reduced by NR4A3 knockdown. We suggest that NR4A3 plays a pro‐inflammatory role in the development of OA, and we also speculate that NR4A3 mainly regulates cartilage matrix‐degrading gene expression under inflammatory conditions via the NF‐κB pathway.     

Silencing of ATP2B1‐AS1 contributes to protection against myocardial infarction in mouse via blocking NFKBIA‐mediated NF‐κB signalling pathway

Myocardial infarction (MI) is an acute coronary syndrome that refers to tissue infarction of the myocardium. This study aimed to investigate the effect of long intergenic non‐protein‐coding RNA (lincRNA) ATPase plasma membrane Ca²⁺ transporting 1 antisense RNA 1 (ATP2B1‐AS1) against MI by targeting nuclear factor‐kappa‐B inhibitor alpha (NFKBIA) and mediating the nuclear factor‐kappa‐B (NF‐κB) signalling pathway. An MI mouse model was established and idenepsied by cardiac function evaluation. It was determined that ATP2B1‐AS1 was highly expressed, while NFKBIA was poorly expressed and NF‐κB signalling pathway was activated in MI mice. Cardiomyocytes were extracted from mice and introduced with a series of mouse ATP2B1‐AS1 vector, NFKBIA vector, siRNA‐mouse ATP2B1‐AS1 and siRNA‐NFKBIA. The expression of NF‐κBp50, NF‐κBp65 and IKKβ was determined to idenepsy whether ATP2B1‐AS1 and NFKBIA affect the NF‐κB signalling pathway, the results of which suggested that ATP2B1‐AS1 down‐regulated the expression of NFKBIA and activated the NF‐κB signalling pathway in MI mice. Based on the data from assessment of cell viability, cell cycle, apoptosis and levels of inflammatory cytokines, either silencing of mouse ATP2B1‐AS1 or overexpression of NFKBIA was suggested to result in reduced cardiomyocyte apoptosis and expression of inflammatory cytokines, as well as enhanced cardiomyocyte viability. Our study provided evidence that mouse ATP2B1‐AS1 silencing may have the potency to protect against MI in mice through inhibiting cardiomyocyte apoptosis and inflammation, highlighting a great promise as a novel therapeutic target for MI.     

LncRNA NR2F1‐AS1 regulates hepatocellular carcinoma oxaliplatin resistance by targeting ABCC1 via miR‐363

Emerging evidence has validated the vital role of long non‐coding RNA (lncRNA) in the chemoresistance of cancer treatment. In the present study, we investigate the function of lncRNA NR2F1‐AS1 on oxaliplatin (OXA) resistance of hepatocellular carcinoma (HCC) and discover the underlying molecular mechanism. Results revealed that lncRNA NR2F1‐AS1 was up‐regulated in oxaliplatin‐resistant HCC tissue and cells using microarray analysis and RT‐PCR. Meanwhile, ABCC1 protein was overexpressed in OXA‐resistant HCC cells (Huh7/OXA and HepG2/OXA). In vitro, NR2F1‐AS1 knockdown reduced the invasion, migration, drug‐resistant gene (MDR1, MRP5, LRP1) and IC50 value in Huh7/OXA and HepG2/OXA cells. In vivo, NR2F1‐AS1 knockdown decreased the tumour weight of HCC cells. Bioinformatics tools and luciferase reporter assay confirmed miR‐363 targeted the 3′‐UTR of NR2F1‐AS1 and ABCC1 mRNA, presenting that NR2F1‐AS1 promoted ABCC1 expression through endogenous sponging miR‐363. In summary, results conclude that NR2F1‐AS1 regulates HCC OXA resistance through targeting miR‐363‐ABCC1 pathway, providing a vital theoretic mechanism and therapeutic target for HCC chemoresistance.     

Aberrantly expressed long non‐coding RNAs in air pollution‐induced congenital defects

Air pollution has been a serious public health issue over the past few decades particularly in developing countries. Air pollution exposure during pregnancy poses potential threat to offspring as the deleterious substances might pass through placenta to alter foetal development. A growing number of studies have demonstrated that long non‐coding RNAs (lncRNAs) participate in the development of many diseases, including congenital defects. Here, we used RNA sequencing to identify differentially expressed lncRNAs in air pollution‐exposed rat embryos compared with control group. Our data suggested that 554 lncRNAs (216 up‐regulated and 338 down‐regulated) were significantly differentially expressed in the air pollution‐exposed embryos. Moreover, potential cellular functions of these deregulated lncRNAs were predicted via KEGG signal pathway/GO enrichment analyses, which suggested the possible involvements of neurological process, sensory perception of smell and the G‐protein signalling pathway. Furthermore, potential functional network of deregulated lncRNAs and their correlated mRNAs in the development of congenital spinal abnormality was established. Our data suggested that lncRNAs may play a vital role in the pathophysiology of air pollution‐exposed congenital spinal malformation.