Long non-coding RNA ANRIL is required for the PRC2 recruitment to and silencing of p15INK4B tumor suppressor gene

Objective To investigate the expression level of antisense non-coding RNA in the INK4 locus (ANRIL) in hepatocellular carcinoma (HCC) tissues and to evaluate its relation to clinicopathological features and prognosis of HCC. Methods Quantitative real-time polymerase chain reaction (qRT-PCR) method was used to detect the expression of ANRIL in HCC tissues and adiacent tissues (n=90) and to analyze its relationship with clinicopathological data. Kaplan-Meier curves and multivariate Cox proportional models were used to study the impact on clinical outcome. Small interfering RNA (siRNA) was used to silence ANRIL and to explore the effects of reduced ANRIL expression on cell growth and metastasis. Results ANRIL expression in HCC tissues was significantly higher than in the adjacent non-tumor tissues (t=13.083, P<0.05). The expression of ANRIL was remarkably associated with the histologic grade (χ2=40.724, P<0.05) and TNM stage (χ2=43.245, P<0.05) . The mean survival time of the patients with high ANRIL was 18.2 months (95%CI: 14.9-21.5 months), shorter than 39.4 months (95%CI: 35.5-43.4 months) in low expression (χ2=47.590, P<0.05). Multivariate analysis suggested that high ANRIL expression was an independent predictor of poor prognosis (HR=2.143, 95%CI: 1.083-4.243, P<0.05). Decreased expression of ANRIL could suppress the cell proliferation, migration and invasion of HCC cells. Conclusion Positive ANRIL expression is negatively correlated with the prognosis of HCC patients. Key words: Carcinoma, hepatocellular; Prognosis; Antisense non-coding RNA in the INK4 locus

Atherosclerosis (AS), with high risk of stroke or cerebrovascular disease, is one of the most common causes of death worldwide. Increasing evidence shows that long non-coding RNA (lncRNA) antisense non-coding RNA in the INK4 locus (ANRIL) is related to atherothrombotic stroke susceptibility and contributes to AS progression. However, the underlying mechanism was not explained yet. Human aorta vascular smooth muscle cells (HA-VSMCs) and human umbilical vein endothelial cells (HUVECs) were treated with oxidized Low Density Lipoprotein (ox-LDL) and considered as AS cell models. Quantitative reverse transcriptase PCR (qRT-PCR) and Western blotting were employed to investigate the mRNA and protein expression level, respectively. Microscopic examination through fluorescent in situ hybridization (FISH) was used to determine the location of ANRIL. Cell proliferation and migration assays were demonstrated to evaluate the functional role of ANRIL in AS. Potential target of ANRIL was determined using Luciferase reporter assay and RNA immunoprecipitation (RIP). ANRIL was upregulated and miR-399-5p was down-regulated in both human atherosclerotic plaques and ox-LDL-induced cells. ANRIL was located in cytoplasm and promoted cell proliferation and migration by sponging miR-399-5p. Further analysis identified fibroblast growth factor receptor substrate 2 (FRS2) as a direct target of miR-399-5p. Finally, RAS/RAF/ERK signal pathway was proved to be involved in the regulation of ANRIL on the progression of AS. These results revealed the underlying mechanism that ANRIL promoted AS progression by sponging miR-399-5p and regulating RAS/RAF/ERK signal pathway, suggesting that ANRIL might be a potential target for the therapeutic strategy of AS.

In the past several years, advances in molecular genetics have been adopted as tools to dissect the cause and pathophysiology of common complex diseases and their associated risk factors in a hypothesis-free approach, using the genome-wide association study design and high-density, single nucleotide polymorphism (SNP) genotyping arrays. Starting in 2007 with the discovery of the chromosome 9p21.3 (Chr9p21.3) locus (see recent review),1 major progress has been made in terms of identification of novel susceptibility loci for coronary artery disease (CAD; ie, genomic regions that are strongly and consistently associated with CAD).2,3 These CAD susceptibility loci are of major interest because they are expected to harbor genes constituting important nodes in biological pathways underlying CAD and hence may serve as shortcuts to discovery of hitherto unknown disease mechanisms. However, causal variants will only occasionally be among those that are directly typed in genome-wide association scans, and the interval within which the etiologic variant(s) are expected to lie can be sizeable, and often contains several genes. Thus, the challenge for the next several years will be to move from statistical association based on genetic markers to identification and functional characterization of individual risk-associated genes, gene variants, biological pathways, and proteins and to elucidation of their roles in the resulting vascular pathology. Article see p 1896 In the rapidly expanding group of robustly associated CAD loci, the Chr9p21.3 locus contributes the largest increase in risk, 1 and 2 copies of the risk allele (allele frequency of 0.50) being associated with a rise in CAD risk of around 20% to 40% and 40% to 70%, respectively. Interestingly, this substantial increase in risk is independent of established risk factors, which suggests that the Chr9p21.3 locus operates through an …

Antisense noncoding RNA in the INK4 locus (ANRIL) has been reported to be upregulated in various types of human cancer, and is also highly expressed in normal human tissue. The aim of the present study was to identify whether ANRIL may be a possible target for colorectal cancer (CRC) therapy. Reverse transcription‑quantitative polymerase chain reaction was used to quantify the expression levels of the long noncoding RNA (lncRNA) ANRIL in 97paired CRC and adjacent non‑neoplastic tissue samples. In addition, the HT29 and RKO human CRC cell lines underwent ANRIL RNAinterference, and knockdown efficiency was evaluated by western blotting. Cell viability, and migratory and invasive ability were subsequently assessed. The CRC tissues were revealed to express higher levels of ANRIL lncRNA compared with the adjacent non‑neoplastic tissues (P<0.05). Furthermore, high ANRIL expression was significantly associated with reduced survival rate (P<0.05). ANRIL gene expression was successfully silenced in human CRC cells. ANRIL knockdown decreased proliferation, inhibited migration and invasion, and reduced the colony‑forming ability of the cells. These data indicated that the lncRNA ANRIL is upregulated in CRC tissues, and is associated with CRC cell pathogenesis. Furthermore, the underlying mechanisms of these effects may be exploited for therapeutic benefit.

Idiopathic pulmonary fibrosis (IPF) is a progressive and life-threatening respiratory disease characterized by worsening lung function due to excessive scarring. The objective of this study was to investigate the role of the long non-coding RNA ANRIL (antisense non-coding RNA in the INK4 locus) in the development of IPF. Our research revealed a significant increase in ANRIL expression in pulmonary fibrosis, consistent with prior studies indicating elevated ANRIL levels in fibrotic tissues. In vitro experiments demonstrated that elevated ANRIL expression promoted fibroblast activation, as evidenced by the upregulation of fibrosis-related markers. Mechanistically, we found that ANRIL interacts with let-7d-5p, a microRNA involved in gene regulation, acting as a sponge for let-7d-5p. Functional experiments confirmed a potential influence of let-7d-5p on fibroblast activation through direct interaction with ANRIL. Furthermore, our investigation identified TGFBR1 as a potential mediator of ANRIL’s fibrogenic effects. Silence of TGFBR1 mitigated the fibrotic phenotype induced by ANRIL overexpression. Collectively, these results suggest that ANRIL promotes fibroblast activation and fibrosis development, possibly through the let-7d-5p/TGFBR1 axis, indicating that ANRIL could be a potential therapeutic target for pulmonary fibrosis.

The chromosome 9p21 (Chr9p21) locus of coronary artery disease has been identified in the first surge of genome-wide association and is the strongest genetic factor of atherosclerosis known today. Chr9p21 encodes the long non-coding RNA (ncRNA) antisense non-coding RNA in the INK4 locus (ANRIL). ANRIL expression is associated with the Chr9p21 genotype and correlated with atherosclerosis severity. Here, we report on the molecular mechanisms through which ANRIL regulates target-genes in trans, leading to increased cell proliferation, increased cell adhesion and decreased apoptosis, which are all essential mechanisms of atherogenesis. Importantly, trans-regulation was dependent on Alu motifs, which marked the promoters of ANRIL target genes and were mirrored in ANRIL RNA transcripts. ANRIL bound Polycomb group proteins that were highly enriched in the proximity of Alu motifs across the genome and were recruited to promoters of target genes upon ANRIL over-expression. The functional relevance of Alu motifs in ANRIL was confirmed by deletion and mutagenesis, reversing trans-regulation and atherogenic cell functions. ANRIL-regulated networks were confirmed in 2280 individuals with and without coronary artery disease and functionally validated in primary cells from patients carrying the Chr9p21 risk allele. Our study provides a molecular mechanism for pro-atherogenic effects of ANRIL at Chr9p21 and suggests a novel role for Alu elements in epigenetic gene regulation by long ncRNAs.

The purpose of the study was to investigate the possible association between ANRIL gene rs4977574-polymorphism and prostate cancer occurrence among men of the Ukrainian population. Materials and methods. A total of 250 males were enrolled in the study. Of these, the experimental group included 184 prostate cancer patients, and the control group included 66 men without a history of malignant tumors. Genotyping of the ANRIL rs4977574 locus was performed by real-time polymerase chain reaction. The reaction was performed on a Quant Studio 5 DX Real-Time instrument (Applied Biosystems, USA) in the presence of TaqMan assays (TaqMan®SNP Assay C_31720978_30). The genotyping results were statistically processed using the SPSS software package (version 17.0). Values of p less than 0.05 were considered as statistically significant. Results and discussion. ANRIL (Antisense Non-coding RNA in the INK4 Locus), also known as CDKN2B-AS1, is a long non-coding RNA (3.8-kb) transcribed from the short arm of the human chromosome 9 (p21.3). ANRIL transcripts promote their main molecular effects through interaction with proteins of Polycomb repressive complex 1 and Polycomb repressive complex 2. Ultimately, this leads to epigenetic cis-inactivation of the tumor growth suppressor genes located in the Chr9p21 region: CDKN2A/p16INK4A, CDKN2A/p14ARF, CDKN2B/p15INK4B. Recent experimental studies have demonstrated the involvement of ANRIL in the development of malignant tumors of different localization. At the same time, there is almost no information about the role of the gene polymorphisms of this RNA in the occurrence of prostate cancer. The possible link between ANRIL gene polymorphism and prostate cancer risk in the Ukrainian population is not fully understood. It was found that the control men and prostate cancer patients did not differ significantly in the frequency of rs4977574-genotypes (p = 0.886). No significant difference was found during the corresponding comparison separately among persons with normal weight, overweight, without, and with the habit of smoking (p &gt;0.05). Analysis of the association of different rs4977574 genotypes of the ANRIL gene with the risk of prostate cancer using logistic regression also did not show a reliable relationship under different models of inheritance, both before and after adjustment for age, body mass index and smoking (p &gt;0.05). Conclusion. Thus, for the first time, we performed an analysis of the relation between ANRIL gene polymorphism and the development of malignant tumors of the genitourinary system in the Ukrainian population. The results showed that the polymorphic locus rs4977574 is not associated with the risk of prostate cancer

Increasing evidence indicates that long non-coding RNAs (lncRNAs) antisense non-coding RNA in the INK4 locus (ANRIL) has been involved in various diseases and promotes tumorigenesis and cancer progression as an oncogenic gene. However, the effect of ANRIL on chemoresistance remains still unknown in colorectal cancer (CRC). Here, we investigated ANRIL expression in 63 cases of colorectal cancer specimens and matched normal tissues. Results revealed that ANRIL was up-regulated in tumor tissues samples from patients with CRC and CRC cell lines. Increased ANRIL expression in CRC was associated with poor clinical prognosis. Kaplan–Meier analysis showed that ANRIL was associated with overall survival of patients with colorectal cancer, and patients with high ANRIL expression tended to have unfavorable outcome. In vitro experiments revealed that ANRIL knockdown significantly inhibited CRC cell proliferation, improved the sensitivity of chemotherapy and promoted apoptosis. Further functional assays indicated that ANRIL overexpression significantly promoted cell chemoresistance by regulating ATP-binding cassette subfamily C member 1 through binding Let-7a. Taken together, our study demonstrates that ANRIL could act as a functional oncogene in CRC, as well as a potential therapeutic target to inhibit CRC chemoresistance.

OP0106 The Impact of Pro-Inflammatory Cytokines on the Expression and Function of Long Noncoding RNA (LNCRNA) in Rheumatoid Arthritis Synovial Fibroblasts

BackgroundBoth DNA genotype and methylation of antisense non-coding RNA in the INK4 locus (ANRIL) have been robustly associated with coronary artery disease (CAD), but the interdependent mechanisms of genotype and methylation remain unclear.MethodsEighteen tag single nucleotide polymorphisms (SNPs) of ANRIL were genotyped in a matched case–control study (cases 503 and controls 503). DNA methylation of ANRIL and the INK4/ARF locus (p14ARF, p15INK4b and p16INK4a) was measured using pyrosequencing in the same set of samples (cases 100 and controls 100).ResultsPolymorphisms of ANRIL (rs1004638, rs1333048 and rs1333050) were significantly associated with CAD (p < 0.05). The incidence of CAD, multi-vessel disease, and modified Gensini scores demonstrated a strong, direct association with ANRIL gene dosage (p < 0.05). There was no significant association between ANRIL polymorphisms and myocardial infarction/acute coronary syndrome (MI/ACS) (p > 0.05). Methylation levels of ANRIL were similar between the two studied groups (p > 0.05), but were different in the rs1004638 genotype, with AA and AT genotype having a higher level of ANRIL methylation (pos4, p = 0.006; pos8, p = 0.019). Further Spearman analyses indicated that methylation levels of ANRIL were positively associated with systolic blood pressure (pos6, r = 0.248, p = 0.013), diastolic blood pressure (pos3, r = 0.213, p = 0.034; pos6, r = 0.220, p = 0.028), and triglyceride (pos4, r = 0.253, p = 0.013), and negatively associated with high-density lipoprotein cholesterol (pos2, r = − 0.243, p = 0.017). Additionally, we identified 12 transcription factor binding sites (TFBS) within the methylated ANRIL region, and functional annotation indicated these TFBS were associated with basal transcription. Methylation at the INK4/ARF locus was not associated with ANRIL genotype.ConclusionsThese results indicate that ANRIL genotype (tag SNPs rs1004638, rs1333048 and rs1333050) mainly affects coronary atherosclerosis, but not MI/ACS. There may be allele-related DNA methylation and allele-related binding of transcription factors within the ANRIL promoter.

Animal cells possess thousands of long non-coding (lnc) RNAs, such as antisense noncoding RNA in the INK4 locus (ANRIL), which have regulatory roles in the cells’ molecular mechanisms, including X-chromosome inactivation, and developmental processes. These lnc RNAs are known to influence the extensive spectrum of age-related disorders. Accordingly, there is evidence for the role of these lnc RNAs in cardiovascular diseases, particularly coronary artery diseases (CAD). The aim of this study was to assess whether the expression of the lnc RNA ANRIL was associated with a susceptibility to CAD by evaluating the expression level of the two transcripts of ANRIL. Peripheral blood was taken from fifty patients affected by CAD and relative expression of ANRIL was determined by Real-Time PCR assay. The obtained data indicated that the EU741058 transcript expression level significantly decreased in CAD patients in comparison with the healthy individuals (P= 0.001). Furthermore, there was no significant association between the NR_003529 transcript expression, and CAD risk in Iranian patients (P=0.751). Our results suggest that the expression level of the EU741058 transcript of ANRIL may be implicated in CAD development, creating a predictive biomarker for CAD patients in future.

Polycomb group proteins (PcG) function as transcriptional repressors of gene expression. The important role of PcG in mediating repression of the INK4b-ARF-INK4a locus, by directly binding to the long noncoding RNA (lncRNA) transcript antisense noncoding RNA in the INK4 locus (ANRIL), was recently shown. INK4b-ARF-INK4a encodes 3 tumor-suppressor proteins, p15(INK4b), p14(ARF), and p16(INK4a), and its transcription is a key requirement for replicative or oncogene-induced senescence and constitutes an important barrier for tumor growth. ANRIL gene is transcribed in the antisense orientation of the INK4b-ARF-INK4a gene cluster, and different single-nucleotide polymorphisms are associated with increased susceptibility to several diseases. Although lncRNA-mediated regulation of INK4b-ARF-INK4a gene is not restricted to ANRIL, both polycomb repressive complex-1 (PRC1) and -2 (PRC2) interact with ANRIL to form heterochromatin surrounding the INK4b-ARF-INK4a locus, leading to its repression. This mechanism would provide an increased advantage for bypassing senescence, sustaining the requirements for the proliferation of stem and/or progenitor cell populations or inappropriately leading to oncogenesis through the aberrant saturation of the INK4b-ARF-INK4a locus by PcG complexes. In this review, we summarize recent findings on the underlying epigenetic mechanisms that link PcG function with ANRIL, which impose gene silencing to control cellular homeostasis as well as cancer development.

A large noncoding RNA called ANRIL (for antisense noncoding RNA in the INK4 locus) has been identified within the p15/CDKN2B-p16/CDKN2A-p14/ARF gene cluster. While the exact role of ANRIL awaited further elucidation, common disease genomewide association studies (GWAS) have surprisingly identified the ANRIL gene as a genetic susceptibility locus shared associated by coronary disease, intracranial aneurysm and also type 2 diabetes. Expression studies have confirmed the coregulation of p15/CDKN2B, p16/CDKN2A, p14/ARF, and ANRIL. Among the cluster, ANRIL expression showed the strongest association with the multiple phenotypes linked to the 9p21.3 region. More recent GWAS also identified ANRIL as a risk locus for gliomas and basal cell carcinomas in accordance with the princeps observation. Moreover, a mouse model has confirmed the pivotal role of ANRIL in regulation of CDKN2A/B expression through a cis-acting mechanism and its implication in proliferation and senescence. The implication of ANRIL in cellular aging has provided an attractive unifying hypothesis to explain its association with various susceptibility risk factors. ANRIL identification emphasizes the underestimated role of long noncoding RNAs. Many GWAS have identified trait-associated SNPs that felt in noncoding genomic regions. It is conceivable to anticipate that long, noncoding RNAs will map to many of these "gene deserts."

The long noncoding RNA (lncRNA) antisense noncoding RNA in the INK4 locus (ANRIL) expression is upregulated in hepatocellular carcinoma (HCC) tissues, and decreased ANRIL expression inhibits cell proliferation, metastasis, and invasion and induces apoptosis in HCC cells. However, the molecular mechanism by which ANRIL is involved in HCC tumorigenesis is unclear. In this study, ANRIL was found to be a significantly upregulated lncRNA in HCC and was associated with the metastasis and poor prognosis of HCC. p53 plays an important role in the mechanism of carcinogenesis. Therefore, we hypothesized that ANRIL plays a biological role by regulating the p53 signaling pathway. To comprehensively evaluate the biological function of ANRIL, bioinformatics analysis, quantitative real-time polymerase chain reaction, Western blotting, wound healing, Transwell, cell colonization assay, cell counting kit-8, reactive oxygen species, JC-1, EdU, and terminal deoxynucleotidyl transferase-mediated dUTP Nick end labeling were performed. The results showed that the knockdown of ANRIL inhibited HCC cell viability, colony forming ability, functions such as metastasis and invasion, and epithelial-mesenchymal transition. Meanwhile, the knockdown of ANRIL also resulted in the decreased expression of the p53 protein. All these effects are tightly intertwined with the regulation of the p53 signaling pathway. Thus, ANRIL may contribute to the development of new drugs for the treatment of human HCC.

Dysregulation of long non-coding RNA (IncRNA) antisense non-coding RNA in the INK4 locus (ANRIL) is associated with the risk of myocardial infarction (MI). Therefore, the present study aimed to determine the mechanisms underlying this association, which is currently poorly understood, to the best of our knowledge. The current study used an in vitro myocardial ischemia and reperfusion (MI/R) model, in which H9c2 cardiomyocytes were exposed to hypoxia/reoxygenation (H/R), which demonstrated that ANRIL expression was downregulated and that ANRIL positively regulated sirtuin 1 (SIRT1) expression following H/R injury. Subsequently, it was demonstrated that ANRIL upregulated SIRT1 expression by sponging microRNA-181a (miR-181a). In addition, ANRIL overexpression reduced lactate dehydrogenase release and apoptosis of H9c2 cardiomyocytes exposed to H/R, indicating that ANRIL prevented H/R-induced cardiomyocyte injury. Moreover, both miR-181a overexpression and SIRT1 knockdown significantly decreased the protective effects of ANRIL on H/R-induced cardiomyocyte injury, thus demonstrating that SIRT1 upregulation via sponging miR-181a is a critical mechanism that mediates the function of ANRIL. These results provided a novel mechanistic insight into the role of ANRIL in H/R-injured cardiomyocytes and suggested that the ANRIL/miR-181a/SIRT1 axis may be a therapeutic target for reducing MI/R injury.