HOTTIP: a critical oncogenic long non-coding RNA in human cancers

The role of long noncoding RNAs in ocular angiogenesis and vascular oculopathy

BACKGROUND

Long noncoding RNAs (lncRNAs) are RNA transcripts over 200 nucleotides in length that do not code for proteins. Initially considered a genomic mystery, an increasing number of lncRNAs have been shown to have vital roles in physiological and pathological conditions by regulating gene expression through diverse mechanisms depending on their subcellular localization. Dysregulated angiogenesis is responsible for various vascular oculopathies, including diabetic retinopathy, retinopathy of prematurity, age-related macular degeneration, and corneal neovascularization. While anti-VEGF treatment is available, it is not curative, and long-term outcomes are suboptimal, and some patients are unresponsive. To better understand these diseases, researchers have investigated the role of lncRNAs in regulating angiogenesis and models of vascular oculopathies. This review summarizes recent research on lncRNAs in ocular angiogenesis, including the pro-angiogenic lncRNAs ANRIL, HOTAIR, HOTTIP, H19, IPW, MALAT1, MIAT, NEAT1, and TUG1, the anti-angiogenic lncRNAs MEG3 and PKNY, and the human/primate specific lncRNAs lncEGFL7OS, discussing their functions and mechanisms of action in vascular oculopathies.

Overcoming chemoresistance and radio resistance in prostate cancer: The emergent role of non-coding RNAs

Prostate cancer (PCa) continues to be a major health concern worldwide, with its resistance to chemotherapy and radiation therapy presenting major hurdles in successful treatment. While patients with localized prostate cancer generally have a good survival rate, those with metastatic prostate cancer often face a grim prognosis, even with aggressive treatments using various methods. The high mortality rate in severe cases is largely due to the lack of treatment options that can offer lasting results, especially considering the significant genetic diversity found in tumors at the genomic level. This comprehensive review examines the intricate molecular mechanisms governing resistance in PCa, emphasising the pivotal contributions of non-coding RNAs (ncRNAs). We delve into the diverse roles of microRNAs, long ncRNAs, and other non-coding elements as critical regulators of key cellular processes involved in CR & RR. The review emphasizes the diagnostic potential of ncRNAs as predictive biomarkers for treatment response, offering insights into patient stratification and personalized therapeutic approaches. Additionally, we explore the therapeutic implications of targeting ncRNAs to overcome CR & RR, highlighting innovative strategies to restore treatment sensitivity. By synthesizing current knowledge, this review not only provides a comprehension of the chemical basis of resistance in PCa but also identifies gaps in knowledge, paving the way for future research directions. Ultimately, this exploration of ncRNA perspectives offers a roadmap for advancing precision medicine in PCa, potentially transforming therapeutic paradigms and improving outcomes for patients facing the challenges of treatment resistance.

rs217727 of lncRNA H19 is Associated with Cervical Cancer Risk in the Chinese Han Population

Background

Long noncoding RNAs (LncRNAs) have been revealed to involve in cervical cancer (CC) developing. The current study was designed to explore the association of SNPs (rs217727, rs2366152, rs1859168, rs10505477) located in the lncRNA H19, HOTAIR, HOTTIP and CASC8 genes with the risk of CC in a Chinese Han population.

Methods

Four SNPs were selected and genotyped in 1426 participants (274 CIN patients, 448 CC patients, and 704 healthy control individuals) using MassArray. The association of these SNPs with susceptibility to CC was evaluated.

Results

Significant differences in allelic distribution of rs217727 were observed in the comparison of CC with control (P = 0.001), indicating the risk of rs217727-A allele in CC (OR = 1.33; 95% CI: 1.12-1.58). The inheritance model analysis revealed that 2AA+GA genotype represented a certain risk of CC (P = 0.001, OR = 1.35; 95% CI: 1.13-1.62). The stratified analysis revealed a risk of the rs217727-A allele for cervical squamous cell carcinoma (SCC) (P = 0.002, OR = 1.33; 95% CI: 1.11-1.60).

Conclusion

rs217727 in lncRNA H19 exhibited a significant correlation with CC susceptibility, particularly SCC, and A/A genotype of this SNP might present as a risk in CC.

iLncDA-RSN: identification of lncRNA-disease associations based on reliable similarity networks

Identification of disease-associated long non-coding RNAs (lncRNAs) is crucial for unveiling the underlying genetic mechanisms of complex diseases. Multiple types of similarity networks of lncRNAs (or diseases) can complementary and comprehensively characterize their similarities. Hence, in this study, we presented a computational model iLncDA-RSN based on reliable similarity networks for identifying potential lncRNA-disease associations (LDAs). Specifically, for constructing reliable similarity networks of lncRNAs and diseases, miRNA heuristic information with lncRNAs and diseases is firstly introduced to construct their respective Jaccard similarity networks; then Gaussian interaction profile (GIP) kernel similarity networks and Jaccard similarity networks of lncRNAs and diseases are provided based on the lncRNA-disease association network; a random walk with restart strategy is finally applied on Jaccard similarity networks, GIP kernel similarity networks, as well as lncRNA functional similarity network and disease semantic similarity network to construct reliable similarity networks. Depending on the lncRNA-disease association network and the reliable similarity networks, feature vectors of lncRNA-disease pairs are integrated from lncRNA and disease perspectives respectively, and then dimensionality reduced by the elastic net. Two random forests are at last used together on different lncRNA-disease association feature sets to identify potential LDAs. The iLncDA-RSN is evaluated by five-fold cross-validation to analyse its prediction performance, results of which show that the iLncDA-RSN outperforms the compared models. Furthermore, case studies of different complex diseases demonstrate the effectiveness of the iLncDA-RSN in identifying potential LDAs.

Long non-coding RNA HOTTIP exerts an oncogenic function by regulating HOXA13 in nasopharyngeal carcinoma

BACKGROUND

The long non-coding RNA HOXA transcript at the distal tip (HOTTIP) and homeobox A13 (HOXA13) have been identified as oncogenes that play a pivotal role in tumorigenesis. However, their specific mechanisms of action in nasopharyngeal carcinoma (NPC) progression remain unclear.

METHODS AND RESULTS

In the present study, RT-qPCR was employed to quantify RNA expression in NPC cells and tissues. Flow cytometry, MTT, CCK8 and colony formation assays were utilized to assess cell apoptosis and proliferation. Transwell assay was conducted to evaluate migration and invasion while Western blotting was performed for protein expression analysis. Our findings revealed that the expression of HOTTIP was significantly upregulated in NPC cell lines. Inhibition of HOTTIP could induce apoptosis and suppress proliferation, clonogenicity, invasion and metastasis in NPC cells. Knockdown of HOTTIP led to downregulation of HOXA13 expression, which subsequently inhibited the proliferation and metastasis in NPC cells. The inhibitory effects on cell proliferation and metastasis caused by HOTTIP silencing were rescued by HOXA13 overexpression. Additionally, there was a significant positive correlation between HOTTIP and HOXA13, which were found to be elevated in NPC tissues compared to normal tissues.

CONCLUSIONS

We have determined that LncRNA HOTTIP facilitates tumorigenesis by modulating the expression of HOXA13 in NPC cells. Targeting HOTTIP/HOXA13 may be a promising therapeutic strategy for NPC.

Comparative transcriptome characterization of esophageal squamous cell carcinoma and adenocarcinoma

Background

Esophageal cancers are primarily categorized as esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). While various (epi) genomic alterations associated with tumor development in ESCC and EAC have been documented, a comprehensive comparison of the transcriptomes in these two cancer subtypes remains lacking.

Methods

We collected 551 gene expression profiles from publicly available sources, including normal, ESCC, and EAC tissues or cell lines. Subsequently, we conducted a systematic analysis to compare the transcriptomes of these samples at various levels, including gene expression, promoter activity, alternative splicing (AS), alternative polyadenylation (APA), and gene fusion.

Results

Seven distinct cluster gene expression patterns were identified among the differentially expressed genes in normal, ESCC, and EAC tissues. These patterns were enriched in the PI3K-Akt signaling pathway and the activation of extracellular matrix organization and exhibited repression of epidermal development. Notably, we observed additional genes or unique expression levels enriched in these shared pathways and biological processes related to tumor development and immune activation. In addition to the differentially expressed genes, there was an enrichment of lncRNA co-expression networks and downregulation of promoter activity associated with the repression of epidermal development in both ESCC and EAC. This indicates a common feature between these two cancer subtypes. Furthermore, differential AS and APA patterns in ESCC and EAC appear to partially affect the expression of host genes associated with bacterial or viral infections in these subtypes. No gene fusions were observed between ESCC and EAC, thus highlighting the distinct molecular mechanisms underlying these two cancer subtypes.

Conclusions

We conducted a comprehensive comparison of ESCC and EAC transcriptomes and uncovered shared and distinct transcriptomic signatures at multiple levels. These findings suggest that ESCC and EAC may exhibit common and unique mechanisms involved in tumorigenesis.

Differential Expression of Non-Coding RNAs in Stem Cell Development and Therapeutics of Bone Disorders

Stem cells' self-renewal and multi-lineage differentiation are regulated by a complex network consisting of signaling factors, chromatin regulators, transcription factors, and non-coding RNAs (ncRNAs). Diverse role of ncRNAs in stem cell development and maintenance of bone homeostasis have been discovered recently. The ncRNAs, such as long non-coding RNAs, micro RNAs, circular RNAs, small interfering RNA, Piwi-interacting RNAs, etc., are not translated into proteins but act as essential epigenetic regulators in stem cells' self-renewal and differentiation. Different signaling pathways are monitored efficiently by the differential expression of ncRNAs, which function as regulatory elements in determining the fate of stem cells. In addition, several species of ncRNAs could serve as potential molecular biomarkers in early diagnosis of bone diseases, including osteoporosis, osteoarthritis, and bone cancers, ultimately leading to the development of new therapeutic strategies. This review aims to explore the specific roles of ncRNAs and their effective molecular mechanisms in the growth and development of stem cells, and in the regulation of osteoblast and osteoclast activities. Furthermore, we focus on and explore the association of altered ncRNA expression with stem cells and bone turnover.

Long noncoding RNA polymorphisms and hepatocellular carcinoma and pancreatic cancer risk

Hepatocellular carcinoma (HCC) and pancreatic cancer (PC) are among serious malignancies with no proper biomarker suffering from poor prognosis and late onset. Regulation of long noncoding RNAs (lncRNAs) is disturbed in tumors, making them appropriate diagnostic markers or therapeutic targets in systemic therapies. The expression and function of some significant lncRNAs are under the influence of SNPs, highlighting their key role in carcinogenesis. This review assesses the associations between SNPs in lncRNAs and HCC and PC risk. A panel of cancer-associated SNPs in lncRNA genes could help evaluate the clinical use of lncRNAs, including their role as diagnostic markers and therapeutic targets. Nonetheless, more large-scale surveys on various ethnic groups are required to validate results.

A Computationally Constructed lncRNA-Associated Competing Triplet Network in Clear Cell Renal Cell Carcinoma

Long noncoding RNAs (lncRNAs) are revealed to be involved in the tumorigenesis and progression of human malignancies mediated by microRNA (miRNA) via the competing endogenous RNA (ceRNA) mechanism, a newly proposed “RNA language.” However, the lncRNA-associated competing triplet (lncACT) network among ceRNA transcripts in clear cell renal cell carcinoma (ccRCC) is currently lacking. We carried out differential expression analysis to identify aberrantly expressed lncRNAs, miRNAs, and mRNAs by analyzing the RNA-seq data of 420 ccRCC tissues and 71 noncancerous kidney tissues obtained from The Cancer Genome Atlas (TCGA). Then, a ccRCC-specific ceRNA network was built using computational algorithms, including miRcode, TargetScan, miRanda, and miRTarBase. In total, 1491 dysregulated lncRNAs were found between normal renal tissues and ccRCC (fold $\text{change}>4$ and false discovery $\text{rate}<0.01$ ). A ceRNA network that comprised of 46 DElncRNAs, 11 DEmiRNAs, and 55 DEmRNAs was established by integrating the lncRNA/miRNA and miRNA/mRNA interactions into lncACTs. Several lncRNAs were identified to be significantly associated with clinical features of ccRCC patients. Notably, four key lncRNAs (TCL6, HOTTIP, HULC, and PCGEM1) were tightly correlated with both patients’ clinical characteristics and overall survival (log-rank $P<0.05$ ), indicating their potential important roles in ccRCC. HOTTIP may be a potential prognostic and therapeutic molecular marker for ccRCC patients. Collectively, our results provide a comprehensive view of the lncRNA-associated ceRNA regulatory network for a better understanding of the mechanisms and prognosis biomarkers for ccRCC.

Emerging roles of long noncoding RNAs in chemoresistance of pancreatic cancer

Pancreatic cancer is one of the most common causes of cancer death in the world due to the lack of early symptoms, metastasis occurrence and chemoresistance. Therefore, early diagnosis by detection of biomarkers, blockade of metastasis, and overcoming chemoresistance are the effective strategies to improve the survival of pancreatic cancer patients. Accumulating evidence has revealed that long noncoding RNA (lncRNA) and circular RNAs (circRNAs) play essential roles in modulating chemosensitivity in pancreatic cancer. In this review article, we will summarize the role of lncRNAs in drug resistance of pancreatic cancer cells, including HOTTIP, HOTAIR, PVT1, linc-ROR, GAS5, UCA1, DYNC2H1-4, MEG3, TUG1, HOST2, HCP5, SLC7A11-AS1 and CASC2. We also highlight the function of circRNAs, such as circHIPK3 and circ_0000284, in regulation of drug sensitivity of pancreatic cancer cells. Moreover, we describe a number of compounds, including curcumin, genistein, resveratrol, quercetin, and salinomycin, which may modulate the expression of lncRNAs and enhance chemosensitivity in pancreatic cancers. Therefore, targeting specific lncRNAs and cicrRNAs could contribute to reverse chemoresistance of pancreatic cancer cells. We hope this review might stimulate the studies of lncRNAs and cicrRNAs, and develop the new therapeutic strategy via modulating these noncoding RNAs to promote chemosensitivity of pancreatic cancer cells.

Potential Key Markers for Predicting the Prognosis of Gastric Adenocarcinoma Based on the Expression of Ferroptosis-Related lncRNA

Background. Gastric cancer is one of the most common malignant tumors, and it ranks third in global cancer-related mortality. This research was aimed at identifying new targeted treatments for gastric adenocarcinoma by constructing a ferroptosis-related lncRNA prognostic feature model. Methods. The gene expression profile and clinical data of gastric adenocarcinoma patients were downloaded from TCGA database. FerrDb database was used to determine the expression of iron death-related genes. We used R software to clean the TCAG gastric adenocarcinoma gene expression cohort and screen iron death-related differential genes and lncRNAs. The potential prognostic markers and immune infiltration characteristics were determined by constructing prognostic model and multivariate validation of lncRNA related to ferroptosis prognosis. Finally, the characteristics of immune infiltration were determined by immune correlation analysis. Results. We identified 26 ferroptosis-related lncRNAs with independent prognostic value. The Kaplan-Meier analysis identified high-risk lncRNAs associated with poor prognosis of STAD. The risk scoring model constructed by AC115619.1, AC005165.1, LINC01614, and AC002451.1 was better than traditional clinicopathological features. The 1-, 3-, and 5-year survival rates of STAD patients were predicted by the nomogram. GSEA reveals the oxidative respiration and tumor-related pathways in different risk groups. Immune analysis found significant differences in the expression of immune checkpoint-related genes TNFSF9, TNFSF4, and PDCD1LG2 between the two groups of patients. Meanwhile, there were significant differences in APC co stimulation, CCR, and checkpoint between the two groups. Conclusion. Based on the prognostic characteristics of ferroptosis-related lncRNAs, we identified the potential ferroptosis-related lncRNAs and immune infiltration characteristics in gastric adenocarcinoma, which will help provide new targeted treatments for gastric adenocarcinoma.

Role of long non-coding RNAs in development and progression of pancreatic cancer

Pancreatic cancer is a kind of digestive tract malignant tumor that has high malignancy and is difficult to diagnose and treat. Recent studies have proved that long non-coding RNAs (lncRNAs) can mediate tumor genesis, proliferation, migration, and metastasis by regulating epigenetic modification, alternative splicing, transcription, and protein translation. LncRNAs play an important role in the occurrence and development of pancreatic cancer. In this review, we review the role of lncRNAs in pancreatic cancer to provide possible diagnostic and therapeutic targets for the treatment of this malignancy.

lncExplore: a database of pan-cancer analysis and systematic functional annotation for lncRNAs from RNA-sequencing data

Over the past few years, with the rapid growth of deep-sequencing technology and the development of computational prediction algorithms, a large number of long non-coding RNAs (lncRNAs) have been identified in various types of human cancers. Therefore, it has become critical to determine how to properly annotate the potential function of lncRNAs from RNA-sequencing (RNA-seq) data and arrange the robust information and analysis into a useful system readily accessible by biological and clinical researchers. In order to produce a collective interpretation of lncRNA functions, it is necessary to integrate different types of data regarding the important functional diversity and regulatory role of these lncRNAs. In this study, we utilized transcriptomic sequencing data to systematically observe and identify lncRNAs and their potential functions from 5034 The Cancer Genome Atlas RNA-seq datasets covering 24 cancers. Then, we constructed the 'lncExplore' database that was developed to comprehensively integrate various types of genomic annotation data for collective interpretation. The distinctive features in our lncExplore database include (i) novel lncRNAs verified by both coding potential and translation efficiency score, (ii) pan-cancer analysis for studying the significantly aberrant expression across 24 human cancers, (iii) genomic annotation of lncRNAs, such as cis-regulatory information and gene ontology, (iv) observation of the regulatory roles as enhancer RNAs and competing endogenous RNAs and (v) the findings of the potential lncRNA biomarkers for the user-interested cancers by integrating clinical information and disease specificity score. The lncExplore database is to our knowledge the first public lncRNA annotation database providing cancer-specific lncRNA expression profiles for not only known but also novel lncRNAs, enhancer RNAs annotation and clinical analysis based on pan-cancer analysis. lncExplore provides a more complete pathway to highly efficient, novel and more comprehensive translation of laboratory discoveries into the clinical context and will assist in reinterpreting the biological regulatory function of lncRNAs in cancer research. Database URL http://lncexplore.bmi.nycu.edu.tw.

HOTTIP-miR-205-ZEB2 Axis Confers Cisplatin Resistance to Ovarian Cancer Cells

Ovarian cancer is a deadly gynecological malignancy with resistance to cisplatin a major clinical problem. We evaluated a role of long non-coding (lnc) RNA HOTTIP (HOXA transcript at the distal tip) in the cisplatin resistance of ovarian cancer cells, using paired cisplatin sensitive and resistant A2780 cells along with the SK-OV-3 cells. HOTTIP was significantly elevated in cisplatin resistant cells and its silencing reversed the cisplatin resistance of resistant cells. HOTTIP was found to sponge miR-205 and therefore HOTTIP silenced cells had higher levels of miR-205. Downregulation of miR-205 could attenuate HOTTIP-silencing effects whereas miR-205 upregulation in resistant cells was found to re-sensitize cells to cisplatin. HOTTIP silencing also led to reduced NF-κB activation, clonogenic potential and the reduced expression of stem cell markers SOX2, OCT4, and NANOG, an effect that could be attenuated by miR-205. Finally, ZEB2 was identified as the gene target of miR-205, thus completing the elucidation of HOTTIP-miR-205-ZEB2 as the novel axis which is functionally involved in the determination of cisplatin resistance in ovarian cancer cells.

Role of Exosomal Non-coding RNAs in Gastric Cancer: Biological Functions and Potential Clinical Applications

Gastric cancer (GC) is one of the most common fatal cancers worldwide. The communication between GC and other cells in the GC microenvironment directly affects GC progression. Recently, exosomes have been revealed as new players in intercellular communication. They play an important role in human health and diseases, including cancer, owing to their ability to carry various bioactive molecules, including non-coding RNAs (ncRNAs). NcRNAs, including micro RNAs, long non-coding RNAs, and circular RNAs, play a significant role in various pathophysiological processes, especially cancer. Increasing evidence has shown that exosomal ncRNAs are involved in the regulation of tumor proliferation, invasion, metastasis, angiogenesis, immune regulation, and treatment resistance in GC. In addition, exosomal ncRNAs have promising potential as diagnostic and prognostic markers for GC. Considering the biocompatibility of exosomes, they can also be used as biological carriers for targeted therapy. This review summarizes the current research progress on exosomal ncRNAs in gastric cancer, focusing on their biological role in GC and their potential as new biomarkers for GC and therapeutics. Our review provides insight into the mechanisms involved in GC progression, which may provide a new point cut for the discovery of new diagnostic markers and therapeutic strategies.

Monitoring HOTTIP levels on extracellular vesicles for predicting recurrence in surgical non-small cell lung cancer patients

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EV HOTTIP analysis during post-surgical follow-up allows early recurrence detection.

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Detection of an increment of EV HOTTIP level in first post-surgical sample predicts recurrence with a sensitivity of 87.5% and specificity of 90.9%.

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Detection of an increment of EV HOTTIP level in first post-surgical sample predicts worse patient outcome.

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EV HOTTIP could be considered as a follow-up biomarker for monitoring recurrence in NSCLC.

In resected non-small cell lung cancer (NSCLC), postsurgical recurrence is the major factor affecting long-term survival. The identification of biomarkers in extracellular vesicles (EV) obtained from serial blood samples after surgery could enhance early detection of relapse and improve NSCLC outcome. Since EV cargo contains long non-coding RNAs (lncRNAs), we aimed to analyze whether the oncogenic lncRNA HOTTIP, which higher expression in tumor tissue was related to worse outcome in NSCLC, could be detected in EV from NSCLC patients and serve as recurrence biomarker. After purification of EVs by ultracentrifugation in 52 serial samples from 18 NSCLC patients, RNA was isolated and HOTTIP was quantified by Real time PCR. We observed that patients that relapsed after surgery displayed increased postsurgical EV HOTTIP levels in comparison with presurgical levels. In the relapsed patients with several samples available between surgery and relapse, we observed an increment in the EV HOTTIP levels when approaching to relapse, which indicated its potential utility for monitoring disease recurrence. When we focused in EV HOTTIP levels in the first post-surgical sample, we observed that the detection of an increment of the expression levels in comparison to presurgical sample, predicted recurrence with high sensitivity (85.7%) and specificity (90.9%) and that patients had shorter time to relapse and shorter overall survival. In conclusion, our pilot study showed that EV HOTTIP is a potential biomarker for monitoring disease recurrence after surgery in NSCLC.

Long noncoding RNAs: role and contribution in pancreatic cancer

Noncoding RNAs are proclaimed to be expressed in various cancer types and one such type is found to be pancreatic ductal adenocarcinoma (PDAC). The long noncoding RNAs (LncRNAs) affect the migration, invasion, and growth of tumor cells by playing important roles in the process of epigenesis, post-transcription, and transcriptional regulation along with the maintenance of apoptosis and cell cycle. It is quite subtle whether the alterations in lncRNAs would impact PDAC progression and development. This review throws a spotlight on the lncRNAs associated with tumor functions: MALAT-1, HOTAIR, HOXA13, H19, LINC01559, LINC00460, SNHG14, SNHG16, DLX6-AS1, MSC-AS1, ABHD11-AS1, DUXAP8, DANCR, XIST, DLEU2, etc. are upregulated lncRNAs whereas GAS5, HMlincRNA717, MIAT, LINC01111, lncRNA KCNK15-AS1, etc. are downregulated lncRNAs inhibiting the invasion and progression of PDAC. These data provided helps in the assessment of lncRNAs in the development, metastasis, and occurrence of PDAC and also play a vital role in the evolution of biomarkers and therapeutic agents for the treatment of PDAC.

The Influence of rs1859168 Polymorphism on Serum Expression of HOTTIP and Its Target miR-615-3p in Egyptian Patients with Breast Cancer

BACKGROUND

Polymorphisms of long noncoding RNAs are lately documented as hazardous factors for the development of numerous tumors. Furthermore, the evaluation of noncoding RNAs has emerged as a novel detector of breast cancer patients. We aimed to genotype the HOXA transcript at the distal tip (HOTTIP) rs1859168 and assess its relationship with the levels of the serum HOTTIP and its target miR-615-3p in patients with breast cancer (BC).

METHODS

One hundred and fifty-one patients with BC, 139 patients with fibroadenoma (FA), and 143 healthy participants were incorporated into the current study. The genotyping of rs1859168 and the measurements of the HOTTIP and miR-615-3p levels were assessed using quantitative real-time PCR.

RESULTS

We revealed a significant association between each of the CC genotypes, C allele, dominant and recessive models, and the increased risk of BC (p = 0.013, p < 0.001, p < 0.001, and p < 0.001, respectively) relative to the healthy controls. Similarly, the CC genotype, C allele, and recessive model were observed to be related to the increased incidence of BC with respect to FA (p < 0.001 for all). A significant upregulation of HOTTIP and a marked decrease of miR-615-3p were verified in patients with BC compared to each of the healthy individuals, patients with FA, and the non-BC group (healthy subjects + FA) (p < 0.001 for all). A significant negative correlation was demonstrated between the expression of HOTTIP and miR-615-3p in the serum of patients with BC. The HOTTIP expression was upregulated, while that of miR-615-3p was downregulated in patients with BC who carried the CC genotype with respect to those who carried the AA or AC genotypes (p < 0.05 for all).

CONCLUSIONS

The genetic variants of rs1859168 are linked to an increased susceptibility to BC. Moreover, HOTTIP and miR-615-3p may be used as novel indicators and targets for the treatment of patients with BC.

Knockdown of lncRNA HOTTIP Inhibits Retinoblastoma Progression by Modulating the miR-101-3p/STC1 Axis

Objective:

Retinoblastoma (RB) is a frequent eye cancer in children. Long non-coding RNA (LncRNA) HOXA transcript at the distal tip (HOTTIP) is aberrantly expressed in cancer tissues. This study explores the underlying mechanism of lncRNA HOTTIP in RB.

Methods:

HOTTIP expression in normal retinal cells and RB cell lines was detected using qRT-PCR. The proliferation of RB cells was measured using CCK-8 and EdU assays, and apoptosis was detected using flow cytometry and Western blotting after the transfection of si-HOTTIP into Y79 cells and pc-HOTTIP into HXO-RB-44 cells. The target relationships between HOTTIP and miR-101-3p, and miR-101-3p and STC1 were predicted by bioinformatics website and verified using dual-luciferase reporter gene assay. The binding of HOTTIP and miR-101-3p was verified using RNA pull-down assay. STC1 mRNA and protein in RB cells were measured using qRT-PCR and Western blotting. Moreover, si-HOTTIP and in-miR-101-3p/in-NC, and si-HOTTIP and pc-STC1/pcDNA were co-transfected into Y79 cells respectively to evaluate cell proliferation and apoptosis. Xenograft study was conducted, and Ki67-positive expression was detected using immunohistochemical staining.

Results:

HOTTIP expression was promoted in RB tissues and cells. Downregulation of HOTTIP inhibited proliferation and promoted apoptosis of Y79 cells, while upregulation of HOTTIP promoted proliferation and inhibited apoptosis of HXO-RB-44 cells. There were target relationships between HOTTIP and miR-101-3p, and miR-101-3p and STC1. Inhibition of miR-101-3p or overexpression of STC1 reversed the effect of si-HOTTIP on the proliferation and apoptosis of RB cells. Xenograft study showed that knockdown of HOTTIP suppressed the growth of RB in vitro.

Conclusion:

It could be concluded that HOTTIP sponged miR-101-3p to upregulate STC1 expression, thereby promoting RB cell proliferation and inhibiting apoptosis.

HOTTIP polymorphism may affect gastric cancer susceptibility by altering HOTTIP expression

Background: Non-coding RNA polymorphisms can affect disease risk and prognosis by influencing gene expression. Here, we first investigated the association between single nucleotide polymorphisms (SNPs) of long non-coding RNA (lncRNA) HOTTIP and gastric cancer risk/prognosis. Methods: A total of five HOTTIP SNPs among 627 gastric cancer cases and 935 controls were tested by Kompetitive Allele Specific PCR (KASP) assay. The functional SNPs underwent eQTL analysis and the expression of HOTTIP was assessed by quantitative RT-PCR. Results: The rs2067087 and rs3807598 SNPs of HOTTIP increased susceptibility to gastric cancer (rs2067087: dominant model, P=0.008, odds ratio (OR) = 1.35; rs3807598: recessive model, P=0.037, OR = 1.29). Both HOTTIP rs2067087 and rs3807598 could affect the expression of mature lncRNA (P=0.003 and P=0.032, respectively). Conclusion: The rs2067087 and rs3807598 SNPs of HOTTIP are associated with gastric cancer risk, possibly by affecting the expression of mature HOTTIP.

H19-Wnt/β-catenin regulatory axis mediates the suppressive effects of apigenin on tumor growth in hepatocellular carcinoma

Hepatocellular Carcinoma (HCC) is one of the leading causes of cancer-related deaths in the world. However, the effective pharmacological approaches remain scanty in clinical practice. As a bioactive flavonoid, apigenin (API) is enriched in common fruits and vegetables. Although pharmacological activities of API have been widely investigated, its biological function in HCC remains obscure. In the present study, we found that API strongly suppressed cell growth and induced apoptosis in HCC cells. Using a xenograft mice model, API was demonstrated to inhibit the in vivo tumor growth. It is known that the long non-coding RNA H19, which is frequently elevated in HCC, plays a vital role in mediating tumorigenesis and cancer progression. Our results demonstrated that H19 was down-regulated by API, and thereby induced the inactivation of the canonical Wnt/β-catenin signaling. In conclusion, our results demonstrated that API was able to suppress tumor growth of HCC through H19-mediated Wnt/β-catenin signaling regulatory axis, suggesting that API may be a promising candidate for developing novel therapeutic approaches against liver cancer.

Hepatitis B Virus DNA Polymerase Restrains Viral Replication Through the CREB1/HOXA Distal Transcript Antisense RNA Homeobox A13 Axis

BACKGROUND AND AIMS

Long noncoding RNAs (lncRNAs) have been associated with infection and hepatitis B virus (HBV)-related diseases, though the underlying mechanisms remain unclear.

APPROACH AND RESULTS

We obtained HBV-HCC lncRNA profiles by deep sequencing and found HOXA distal transcript antisense RNA (HOTTIP) to be significantly up-regulated. RT-qPCR indicated that HOTTIP is highly expressed in HBV-positive hepatoma tissue and induced by HBV in vitro. Virological experiments showed that HOTTIP significantly suppresses the generation of hepatitis B viral surface antigen, hepatitis B viral e antigen and HBV replication. Homeobox A13 (HOXA13), a downstream factor of HOTTIP, was found to bind to HBV enhancer I and X promotor to repress the production of HBV pregenome RNA (pgRNA) and total RNA as well as HBV replication, suggesting that HOXA13 mediates HOTTIP-induced suppression of HBV replication. More interestingly, HBV DNA polymerase (DNA pol) binds to and stabilizes cAMP-responsive element-binding protein 1 (CREB1) mRNA to facilitate translation of the protein, which, in turn, binds to the regulatory element of HOTTIP to promote its expression.

CONCLUSIONS

Our findings demonstrate that HBV DNA pol attenuates HBV replication through activation of the CREB1-HOTTIP-HOXA13 axis. These findings shed light on the mechanism by which HBV restrains replication to contribute to persistent infection.

LINC00460/DHX9/IGF2BP2 complex promotes colorectal cancer proliferation and metastasis by mediating HMGA1 mRNA stability depending on m6A modification

Background

Increasing studies have shown that long noncoding RNAs (lncRNAs) are pivotal regulators participating in carcinogenic progression and tumor metastasis in colorectal cancer (CRC). Although lncRNA long intergenic noncoding RNA 460 (LINC00460) has been reported in CRC, the role and molecular mechanism of LINC00460 in CRC progression still requires exploration.

Methods

The expression levels of LINC00460 were analyzed by using a tissue microarray containing 498 CRC tissues and their corresponding non-tumor adjacent tissues. The correlations between the LINC00460 expression level and clinicopathological features were evaluated. The functional characterization of the role and molecular mechanism of LINC00460 in CRC was investigated through a series of in vitro and in vivo experiments.

Results

LINC00460 expression was increased in human CRC, and high LINC00460 expression was correlated with poor five-year overall survival and disease-free survival. LINC00460 overexpression sufficiently induced the epithelial–mesenchymal transition and promoted tumor cell proliferation, migration, and invasion in vitro and tumor growth and metastasis in vivo. In addition, LINC00460 enhanced the protein expression of high-mobility group AT-hook 1 (HMGA1) by directly interacting with IGF2BP2 and DHX9 to bind the 3′ untranslated region (UTR) of HMGA1 mRNA and increased the stability of HMGA1 mRNA. In addition, the N6-methyladenosine (m6A) modification of HMGA1 mRNA by METTL3 enhanced HMGA1 expression in CRC. Finally, it suggested that HMGA1 was essential for LINC00460-induced cell proliferation, migration, and invasion.

Conclusions

LINC00460 may be a novel oncogene of CRC through interacting with IGF2BP2 and DHX9 and bind to the m6A modified HMGA1 mRNA to enhance the HMGA1 mRNA stability. LINC00460 can serve as a promising predictive biomarker for the diagnosis and prognosis among patients with CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01857-2.

Long non-coding RNA MCM3AP-AS1 facilitates colorectal cancer progression by regulating the microRNA-599/ARPP19 axis

Colorectal cancer (CRC) is one of the most aggressive malignancies worldwide. Increasing evidence has indicated that microRNA (miR)-599 is involved in the occurrence and development of different types of tumors, such as breast cancer and glioma. However, the role of miR-599 in CRC remains unclear. Thus, the present study aimed to identify the regulatory mechanism of miR-599 in CRC progression. Reverse transcription-quantitative PCR was used to analyze the expression levels of MCM3AP-AS1, miR-599 and ARPP19, and Cell Counting Kit-8 and Transwell assays were used to determine the cell proliferation and migration of CRC cells. In addition, a Dual-luciferase reporter assay was used to analyze the direct interaction between miR-599 and MCM3AP-AS1 or ARPP19. Reverse transcription-quantitative PCR analysis demonstrated that miR-599 expression decreased in patients with CRC and in CRC cell lines, while miR-599 overexpression inhibited cell proliferation and migration abilities in vitro. MCM3AP-AS1 was identified as a molecular sponge of miR-599, and further investigation indicated that MCM3AP-AS1 silencing inhibited cell proliferation and migration of the CRC cell lines. In addition, ARPP19 was identified as a target gene of miR-599, and MCM3AP-AS1-knockdown decreased ARPP19 mRNA expression and increased miR-599 expression. Furthermore, silencing ARPP19 inhibited the proliferation and migration of the CRC cell lines. The results also demonstrated that MCM3AP-AS1 promoted CRC cell progression by regulating the miR-599/ARPP19 axis. Taken together, the results of the present study suggest that MCM3AP-AS1 may be a novel therapeutic target for patients with CRC.

Long non-coding RNA ANRIL polymorphisms in papillary thyroid cancer and its severity

Background: Long non-coding RNAs are likely to have a role in the pathogenesis of many diseases, including cancer. We hypothesised an effect of certain ANRIL single nucleotide polymorphisms (SNPs) in papillary thyroid cancer. Methods: Genomic ANRIL SNPs in rs11333048, rs4977574, rs1333040 and rs10757274 were determined in 134 papillary thyroid cancer patients and 155 age- and sex-matched controls. Results: None of the ANRIL SNPs were individually linked to papillary thyroid cancer. However, the AAAC haplotype (A from rs11333048, A from rs4977574, A from rs1333040 and C from rs10757274, respectively) showed a protective effect from papillary thyroid cancer whilst the CAAC and CAGT haplotypes were associated with cancer. The rs1333048 CC variant was more frequent in patients with larger tumour size (≥1 cm) in a recessive model (OR 3.4 [95%CI, 1.1-11], P = 0.035). The rs4977574 AC variant was associated with smaller tumour size in an over-dominant model (OR 0.4 [95%CI, 0.2-1.0], P = 0.041). SNPs in rs10757274 (AA: p = 0.045) and rs1333040 (CC: p = 0.019) are linked to a lower likelihood of III-IV cancer stages in dominant or codominant models. Conclusions: Certain haplotypes of ANRIL SNPs are associated with papillary thyroid cancer. ANRIL rs1333048 and rs4977574 variants were associated with larger and smaller tumour sizes, respectively. rs10757274 and rs1333040 variants might lead to lower III-IV cancer stages. These SNPs may be important in the diagnosis of this form of thyroid cancer.

SNP-SNP interactions of oncogenic long non-coding RNAs HOTAIR and HOTTIP on gastric cancer susceptibility

Genetic variants within oncogenic long non-coding RNAs HOTAIR and HOTTIP may affect their gene expression levels, thereby modifying genetic susceptibility to gastric cancer (GC). In a hospital-based study in Ardabil-a very high-risk area in North-West Iran, 600 blood samples from 300 GC patients and 300 healthy controls were recruited for genotyping. Seven HOTAIR (i.e., rs17720428, rs7958904, rs1899663, and rs4759314) and HOTTIP (i.e., rs3807598, rs17501292, and rs1859168) 'tag' single nucleotide polymorphisms (SNPs) were genotyped by the Infinium HTS platform. The rs17720428, rs7958904, and rs1899663 tagSNPs significantly increased GC risk under dominant models by 1.5-, 1.57-, and 1.5-fold, respectively. The G-C-T-A haplotype of HOTAIR tagSNPs increased the risk of GC by 1.31-fold. No significant association was found between HOTTIP SNPs and the risk of GC. HOTAIR and HOTTIP variants were also not associated with any clinicopathologic characteristics. The SNP-SNP interaction of HOTAIR rs17720428/rs7958904 with HOTTIP rs1859168 was associated with an increased risk of GC (rs17720428 TG-rs1859168 CC, OR = 1.76; rs7958904 GC-rs1859168 CC, OR = 1.85; rs7958904 CC-rs1859168 CC, OR = 1.86). Interestingly, the SNP-SNP interaction of HOTAIR rs1899663 with HOTTIP rs1859168 strongly increased the risk of GC (rs1899663 GT-rs1859168 CC, OR = 4.3; rs1899663 TT-rs1859168 CC, OR = 9.37; rs1899663 TT-rs1859168 CA, OR = 6.59). We showed that the HOTAIR rs17720428, rs7958904, and rs1899663 tagSNPs and their interactions with the HOTTIP rs1859168 polymorphism significantly increased the risk of GC. Specifically, novel SNP-SNP interactions between HOTAIR and HOTTIP tagSNPs have a larger impact than individual SNP effects on GC risk, thereby providing us with valuable information to reveal potential biological mechanisms for developing GC.

lncRNA and Mechanisms of Drug Resistance in Cancers of the Genitourinary System

Available systemic treatment options for cancers of the genitourinary system have experienced great progress in the last decade. However, a large proportion of patients eventually develop resistance to treatment, resulting in disease progression and shorter overall survival. Biomarkers indicating the increasing resistance to cancer therapies are yet to enter clinical routine. Long non-coding RNAs (lncRNA) are non-protein coding RNA transcripts longer than 200 nucleotides that exert multiple types of regulatory functions of all known cellular processes. Increasing evidence supports the role of lncRNAs in cancer development and progression. Additionally, their involvement in the development of drug resistance across various cancer entities, including genitourinary malignancies, are starting to be discovered. Consequently, lncRNAs have been suggested as factors in novel therapeutic strategies to overcome drug resistance in cancer. In this review, the existing evidences on lncRNAs and their involvement in mechanisms of drug resistance in cancers of the genitourinary system, including renal cell carcinoma, bladder cancer, prostate cancer, and testicular cancer, will be highlighted and discussed to facilitate and encourage further research in this field. We summarize a significant number of lncRNAs with proposed pathways in drug resistance and available reported studies.

Human Long Noncoding RNA Interactome: Detection, Characterization and Function

The application of a new generation of sequencing techniques has revealed that most of the genome has already been transcribed. However, only a small part of the genome codes proteins. The rest of the genome "dark matter" belongs to divergent groups of non-coding RNA (ncRNA), that is not translated into proteins. There are two groups of ncRNAs, which include small and long non-coding RNAs (sncRNA and lncRNA respectively). Over the last decade, there has been an increased interest in lncRNAs and their interaction with cellular components. In this review, we presented the newest information about the human lncRNA interactome. The term lncRNA interactome refers to cellular biomolecules, such as nucleic acids, proteins, and peptides that interact with lncRNA. The lncRNA interactome was characterized in the last decade, however, understanding what role the biomolecules associated with lncRNA play and the nature of these interactions will allow us to better understand lncRNA's biological functions in the cell. We also describe a set of methods currently used for the detection of lncRNA interactome components and the analysis of their interactions. We think that such a holistic and integrated analysis of the lncRNA interactome will help to better understand its potential role in the development of organisms and cancers.

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.

A prognostic long non-coding RNA-associated competing endogenous RNA network in head and neck squamous cell carcinoma

BACKGROUND

This study aimed to develop multi-RNA-based models using a competing endogenous RNA (ceRNA) regulatory network to provide survival risk prediction in head and neck squamous cell carcinoma (HNSCC).

METHODS

All long non-coding RNA (lncRNA), microRNA (miRNA), and mRNA expression data and clinicopathological features related to HNSCC were derived from The Cancer Genome Atlas. Differentially expressed RNAs were calculated using R. Prognostic factors were identified using univariate Cox regression analysis. Functional analysis was performed using GO, KEGG pathways, and PPI network. Based on the results, we derived a risk signature and compared high- and low-risk subgroups using LASSO regression analysis. Survival analysis and the relationship between risk signature and clinicopathological features were performed using log-rank tests and Cox regression analysis. A ceRNA regulatory network was constructed, and prognostic lncRNAs and miRNA expression levels were validated in vitro and in vivo.

RESULTS

A list of 207 lncRNAs, 18 miRNAs and 362 mRNAs related to overall survival was established. Five lncRNAs (HOTTIP, LINC00460, RMST, SFTA1P, and TM4SF19-AS1), one miRNA (hsa-miR-206), and one mRNA (STC2) were used to construct the ceRNA network. Three prognostic models contained 13 lncRNAs, eight miRNAs, and 17 mRNAs, which correlated with the patient status, disease-free survival (DFS), stage, grade, T stage, N stage, TP53 mutation status, angiolymphatic invasion, HPV status, and extracapsular spread. KEGG pathway analysis revealed significant enrichment of "Transcriptional misregulation in cancer" and "Neuroactive ligand-receptor interaction." In addition, HOTTIP, LINC00460, miR-206 and STC2 were validated in GTEx data, GEO microarrays and six HNSCC cell lines.

CONCLUSIONS

Our findings clarify the interaction of ceRNA regulatory networks and crucial clinicopathological features. These results show that prognostic biomarkers can be identified by constructing multi-RNA-based prognostic models, which can be used for survival risk prediction in patients with HNSCC.

Long non‑coding RNAs in HBV‑related hepatocellular carcinoma (Review)

Hepatitis B virus (HBV)‑related hepatocellular carcinoma (HCC) is a global health problem that accounts for more than half of total liver cancer cases in developing countries. Despite the growing number of researches conducted, the molecular mechanism underlying the development of HCC remains elusive. Long non‑coding RNAs (lncRNAs), which are non‑coding RNAs >200 nt in length that were previously considered to be transcriptional noise, have been found to be dysregulated in HBV‑related HCC with the help of high‑throughput omics techniques. Subsequent investigations revealed that aberrant expression of lncRNAs may affect the risk of HBV‑related HCC through diverse mechanisms, including epigenetic silencing of transcriptional activation, alternative splicing, molecular sponging, modulating protein stability, and by serving as precursors of miRNAs. Although the sensitivity and specificity of lncRNAs must be further validated, a number of circulating lncRNAs have been identified as useful biomarkers for HBV‑related HCC. In addition to these findings, recent studies also unveiled that certain genetic polymorphisms in lncRNAs may affect the occurrence and prognosis of HBV‑related HCC. The aim of the present review was to provide an overview of the mechanisms underlying the involvement of lncRNAs in HBV‑related HCC. Subsequently, lncRNAs found to be dysregulated in HBV‑related HCC were focused on and current findings on circulating lncRNAs and their genetic polymorphisms were discussed.

LncRNAs as Chromatin Regulators in Cancer: From Molecular Function to Clinical Potential

During the last decade, high-throughput sequencing efforts in the fields of transcriptomics and epigenomics have shed light on the noncoding part of the transcriptome and its potential role in human disease. Regulatory noncoding RNAs are broadly divided into short and long noncoding transcripts. The latter, also known as lncRNAs, are defined as transcripts longer than 200 nucleotides with low or no protein-coding potential. LncRNAs form a diverse group of transcripts that regulate vital cellular functions through interactions with proteins, chromatin, and even RNA itself. Notably, an important regulatory aspect of these RNA species is their association with the epigenetic machinery and the recruitment of its regulatory apparatus to specific loci, resulting in DNA methylation and/or post-translational modifications of histones. Such epigenetic modifications play a pivotal role in maintaining the active or inactive transcriptional state of chromatin and are crucial regulators of normal cellular development and tissue-specific gene expression. Evidently, aberrant expression of lncRNAs that interact with epigenetic modifiers can cause severe epigenetic disruption and is thus is closely associated with altered gene function, cellular dysregulation, and malignant transformation. Here, we survey the latest breakthroughs concerning the role of lncRNAs interacting with the epigenetic machinery in various forms of cancer.

Long noncoding RNA HOTTIP overexpression: A potential prognostic biomarker in prostate cancer

HOXA transcript at the distal tip (HOTTIP) is a long noncoding RNA (lncRNA), which is >200 nucleotides in length. HOTTIP expression has been demonstrated to play a crucial oncogenic role in cancer pathogenesis, and is said to be associated with poor human cancer prognosis. In prostate cancer, HOTTIP has been identified as an oncogene, but its clinicopathologic significance remains unclear. Array-based qRT-PCR was used to investigate lncRNA levels in 10 pairs of prostate cancer tissues and non-neoplastic parenchyma. Tissue microarray (TMA) was constructed using a total of 70 surgically resected prostatic adenocarcinoma tissues obtained from the Korea University Anam Hospital from 2009 to 2013. HOTTIP expression was determined by RNA in situ hybridization(ISH) and was correlated with clinicopathologic features. Increased HOTTIP expression was observed in all available prostate cancer tissue specimens compared with that in paired normal tissue. High HOTTIP expression was positively associated with bad clinicopathologic features, including higher pathologic T stage (p < 0.001), presence of extraprostatic extension (p < 0.001), seminal vesicle invasion (p < 0.001), perineural invasion (p < 0.001), and the tumor involvement of resection margin (p = 0.044). In particular, significantly increased HOTTIP expression was observed in specimens from patients in the high or very high-risk group, according to the 2018 National Comprehensive Cancer Network (NCCN) guidelines (p < 0.001). Also, patients with high HOTTIP expression showed poorer overall survival than those with low expression. In conclusion, we analytically validated the poor prognostic significance of HOTTIP overexpression and its association with bad clinicopathologic features, and present HOTTIP as a potential prognostic biomarker in prostate cancer.

Diabetic Retinopathy, lncRNAs, and Inflammation: A Dynamic, Interconnected Network

Diabetic retinopathy (DR) is reaching epidemic levels globally due to the increase in prevalence of diabetes mellitus (DM). DR also has detrimental effects to quality of life, as it is the leading cause of blindness in the working-age population and the most common cause of vision loss in individuals with DM. Over several decades, many studies have recognized the role of inflammation in the development and progression of DR; however, in recent years, accumulating evidence has also suggested that non-coding RNAs, especially long non-coding (lncRNAs), are aberrantly expressed in diabetes and may play a putative role in the development and progression of DR through the modulation of gene expression at the transcriptional, post-transcriptional, or epigenetic level. In this review, we will first highlight some of the key inflammatory mediators and transcription factors involved in DR, and we will then introduce the critical roles of lncRNAs in DR and inflammation. Following this, we will discuss the implications of lncRNAs in other epigenetic mechanisms that may also contribute to the progression of inflammation in DR.

LIFR-AS1 modulates Sufu to inhibit cell proliferation and migration by miR-197-3p in breast cancer

Numerous evidence has recently demonstrated that long non-coding RNAs (lncRNAs) play vital roles in the oncogenesis and development of a wide range of human neoplasms. Leukemia inhibitory factor receptor antisense RNA 1 (LIFR-AS1), a novel cancer-related lncRNA, has been reported to be under-expressed in breast cancer and associated with poor prognosis. However, the exact role of LIFR-AS1 in breast cancer remains largely unclear. The present study aimed to investigate the biological role of LIFR-AS1 in breast cancer and clarify the potential molecular mechanisms. In the present study, we found that LIFR-AS1 was significantly down-regulated in both tissues and cell lines. Furthermore, over-expression of LIFR-AS1 inhibited breast cancer cell proliferation, colony formation, migration and invasion, whereas knockdown of LIFR-AS1 promoted breast cancer cell proliferation, colony formation, migration and invasion. Moreover, LIFR-AS1 was observed to up-regulate suppressor of fused gene (Sufu) expression by competitively binding to miR-197-3p in breast cancer cells. Notably, miR-197-3p inhibitor reversed the promoting effects of LIFR-AS1 knockdown on breast cancer cell proliferation, colony formation, migration and invasion. Additionally, LIFR-AS1 knockdown promoted tumor growth in vivo. To sum up, our results imply the tumor-suppressing role of LIFR-AS1 in breast cancer.

Differential expression profiling of long non-coding RNA GAS5 and miR-126-3p in human cancer cells in response to sorafenib

Long non-coding RNAs (lncRNAs) and microRNAs are involved in numerous physio-pathological conditions included cancer. To better understand the molecular mechanism of the oral antitumor multikinase inhibitor sorafenib, we profiled the expression of a panel of lncRNAs and miRNAs by qPCR array in a sorafenib-treated hepatocellular carcinoma (HCC) cell line. Among the most affected ncRNAs, we found that sorafenib mediated the dysregulation of the lncRNAs GAS5, HOTTIP and HOXA-AS2 and the miR-126-3p, in a panel of human cancer cell lines (HCC, renal and breast carcinomas). By luciferase gene reporter assay, we discovered that GAS5 may act as a sponge for miR-126-3p in HCC cells. The expression level of GAS5 and miR-126-3p was verified in human liquid and/or solid biopsies from HCC patients. miR-126-3p expression in HCC tissues was decreased respect to their correspondent peritumoral tissues. The levels of plasmatic circulating miR-126-3p and GAS5 were significantly higher and lower in HCC patients compared to healthy subjects, respectively. This study highlighted the capability of sorafenib to modulate the expression of a wide range of ncRNAs and specifically, GAS5 and miR-126-3p were involved in the response to sorafenib of different cancer cell types.

lncRNA HOTTIP facilitates osteosarcoma cell migration, invasion and epithelial-mesenchymal transition by forming a positive feedback loop with c-Myc

Homeobox A transcript at the distal tip (HOTTIP) is an oncogenic long non-coding RNA in cancer. The aim of the present study was to investigate the function and mechanism of HOTTIP in the aggressive behaviors of human osteosarcoma (OS) cells. Expression levels of HOTTIP and epithelial-mesenchymal transition (EMT) markers were determined by reverse transcription-quantitative PCR. Cell invasive and migratory abilities were evaluated in vitro using Matrigel and wound healing assays, respectively. Knockdown of HOTTIP expression was achieved by small interfering RNA-mediated silencing. Overexpression of c-Myc was accomplished by transfecting cultured cells with a c-Myc overexpression plasmid. HOTTIP was demonstrated to be upregulated in OS tissues and cell lines; knockdown of HOTTIP inhibited OS cell migration, invasion and EMT, and suppressed c-Myc expression. In addition, overexpression of c-Myc increased HOTTIP expression and enhanced OS cell migration and invasion. HOTTIP promoted cell migration and invasion by upregulating c-Myc in OS. The positive feedback loop formed by HOTTIP and c-Myc may contribute to OS progression, and HOTTIP may act as a therapeutic target for OS.

Role of Autophagy in Renal Cancer

Autophagy is a highly conserved catabolic process with critical functions in maintenance of cellular homeostasis under normal growth conditions and in preservation of cell viability under stress. The role of autophagy in cancer is dual-sided. Autophagy-deficient cells are often more tumorigenic than their wild type counterparts in association with DNA damage accumulation, oxidative stress. At the same time, autophagy is a major cell survival mechanism. In recent years, it has been well demonstrated that autophagy may have relation with renal cell carcinoma (RCC). This review focuses on the research progress in relation between autophagy and RCC and the pharmacologic manipulation of autophagy for RCC treatment.

Prognostic value of lncRNA FEZF1 antisense RNA 1 over-expression in oncologic outcomes of patients with solid tumors

BACKGROUND

FEZ family zinc finger 1 antisense RNA 1 (FEZF1-AS1), as a novel lncRNA, was reported to be up-regulated in various cancers and involved in tumor progression. This study systematically assessed the prognostic value of FEZF1-AS1 in solid tumors.

METHODS

Web of Science, PubMed, EMBASE, Chinese National Knowledge Infrastructure, and Wanfang databases were searched for eligible studies that evaluated the prognostic role of FEZF1-AS1 expression in cancer patients. Pooled hazard ratios (HRs) and combined odds ratios (ORs) with their 95% confidence intervals (CIs) were calculated. The meta-analysis was conducted using Stata/SE 14.1.

RESULTS

Fifteen original studies involving 1378 patients were enrolled. Pooled results showed that increased expression of FEZF1-AS1 significantly correlated with shorter overall survival (OS) in cancer patients (HR 2.04, 95% CI 1.60-2.47), and also shorter disease-free survival (DFS) (HR 2.08, 95% CI 1.27-2.89). Additionally, the combined ORs indicated that increased FEZF1-AS1 expression was significantly associated with lymph node metastasis (OR 3.35, 95% CI 1.98-5.67), distant metastasis (OR 3.10, 95% CI 1.86-5.15), poor tumor differentiation (OR 2.90, 95% CI 1.45-5.80), high depth of tumor invasion (OR 2.72, 95% CI 1.36-5.43), and advanced clinical stage (OR 2.76, 95% CI 1.75-4.35). Expression analysis using the Gene Expression Profiling Interactive Analysis database indicated that the expression of FEZF1-AS1 was higher in tumor tissues than that in the corresponding normal tissues. The results of survival analysis revealed that increased FEZF1-AS1 expression was correlated with poor OS and DFS in cancer patients.

CONCLUSIONS

LncRNA FEZF1-AS1 may serve as a valuable prognostic biomarker for clinical outcomes in various solid tumors.

HOX cluster-embedded antisense long non-coding RNAs in lung cancer

Homeobox (HOX) genes play vital roles in embryonic development and oncogenesis. In humans, there are 39 HOX genes found in four clusters that are located on different chromosomes. The HOX clusters also contain numerous non-protein-coding RNAs, including some lncRNAs. The HOX cluster-embedded lncRNAs (HOX-lncRNAs), most notably, HOTTIP and HOTAIR play a major role in the regulation of their adjacent coding genes. Recently, most HOX-lncRNAs have been shown to impact tumorigenesis and cancer progression. Several HOX-lncRNAs, including HOTTIP, HOXA11-AS, HOTAIRM1, HOXA-AS3, HOXA10-AS, HOTAIR, and HAGLR, are dysregulated in lung cancer. Moreover, their expression levels are correlated with the clinical features of this disease. These HOX-lncRNAs regulate the proliferation, invasion, migration, and chemo-resistance of lung cancer cells through various molecular mechanisms. Although lncRNAs have received much attention lately, the functions of some HOX-lncRNAs in the development of cancer are unclear. Thus, HOX-embedded lncRNAs should be widely investigated in cancer. Here, we review the functions of HOX-lncRNAs in lung cancer.

Four novel polymorphisms in long non-coding RNA HOTTIP are associated with the risk and prognosis of colorectal cancer

Background: The role of long non-coding RNA (lncRNA) HOXA transcript at the distal tip (HOTTIP) as an oncogene in varieties of human cancer including colorectal cancer (CRC) has been extensively researched. The expression and function of lncRNAs could be affected by single nucleotide polymorphisms (SNPs), which are associated with cancer susceptibility and prognosis. However, no investigation has focused on the association between HOTTIP SNPs and CRC. The aim of the present study was to explore the association of polymorphisms in the lncRNA HOTTIP gene with CRC risk and prognosis. Methods: A total of 1848 subjects were enrolled in our study, including 884 CRC cases and 964 controls. Genotyping for five HOTTIP tagSNPs (rs3807598, rs17501292, rs2067087, rs17427960, and rs78248039) was performed by applying Kompetitive allele specific PCR (KASP). Results: The results showed three SNPs (rs3807598, rs2067087, and rs17427960) were associated with enhanced CRC risk both in overall and stratified analysis. One polymorphism, rs17501292, could improve the overall survival (OS) of CRC patients in the tumor of ulcerative/invasive-type subgroup. Conclusion: These findings suggest HOTTIP SNPs could potentially be predictive biomarkers for CRC risk and prognosis. The present study provides clues for further exploration of novel lncRNA-based genetic biomarkers to predict CRC susceptibility as well as clinical outcome.

Long non-coding RNA PCAT6 targets miR-204 to modulate the chemoresistance of colorectal cancer cells to 5-fluorouracil-based treatment through HMGA2 signaling

Colorectal cancer (CRC) is still the third most common cancer in the world with a limited prognosis due to the chemoresistance of CRC cells to 5‐fluorouracil (5‐FU)‐based chemotherapy. In our previous study, we revealed that miR‐204 overexpression could sensitize CRC cell to 5‐FU treatment through targeting HMGA2/PI3K signaling pathway; however, miR‐204 expression in CRC tissues is abnormally downregulated. Long non‐coding RNAs (lncRNAs) dysregulation has been reported in human diseases, including cancer. Also, lncRNA can regulate cancer cell proliferation, invasion, migration, as well as chemoresistance. LncRNA prostate cancer‐associated transcript 6 (PCAT6) acts as an oncogene in many cancers; herein, PCAT6 expression was abnormally upregulated in CRC tissues and cell lines, suggesting its potential role in CRC. Further, we assessed the specific function and mechanism of PCAT6 in CRC. Furthermore, we revealed that PCAT6 knockdown attenuated CRC chemoresistance to 5‐FU through miR‐204/HMGA2/PI3K; miR‐204 inhibition could partially reverse the effect of PCAT6 knockdown. Taken together, we demonstrate that the abnormal PCAT6 overexpression inhibits miR‐204 expression in CRC, thereby promoting HMGA2/PI3K signaling activity, ultimately enhancing the chemoresistance of CRC cells to 5‐FU; PCAT6 represents a promising target for dealing with CRC chemoresistance.

Long Non-coding RNA in Neuronal Development and Neurological Disorders

Long non-coding RNAs (lncRNAs) are transcripts which are usually more than 200 nt in length, and which do not have the protein-coding capacity. LncRNAs can be categorized based on their generation from distinct DNA elements, or derived from specific RNA processing pathways. During the past several decades, dramatic progress has been made in understanding the regulatory functions of lncRNAs in diverse biological processes, including RNA processing and editing, cell fate determination, dosage compensation, genomic imprinting and development etc. Dysregulation of lncRNAs is involved in multiple human diseases, especially neurological disorders. In this review, we summarize the recent progress made with regards to the function of lncRNAs and associated molecular mechanisms, focusing on neuronal development and neurological disorders.

Long noncoding RNA HOTTIP alleviates oxygen-glucose deprivation-induced neuronal injury via modulating miR-143/hexokinase 2 pathway

HOXA transcript at the distal tip (HOTTIP), which is a long noncoding RNA, plays an important role in multiple cancers and in coronary artery disease. Elevated microRNA-143 (miR-143) expression causes impaired glucose uptake that is responsible for the ischemic cerebral injury. However, the role and mechanism of HOTTIP in ischemic stroke are still unknown. The expression of HOTTIP and miR-143 was first detected in mouse models of transient middle cerebral artery occlusion and in primary neurons exposed to oxygen-glucose deprivation (OGD). We used gain-of function and loss-of function approaches in vitro to investigate the effect and mechanism of HOTTIP on ischemic stroke by evaluating cell viability, apoptosis, and glycolytic metabolism of neurons exposed to OGD. The HOTTIP expression was decreased, whereas miR-143 increased in experimental ischemic stroke models. Overexpression of HOTTIP by the pcDNA3.1-HOTTIP plasmid significantly increased cell viability, glucose uptake, and the expression of hexokinase 2 (HK-2) and pyruvate kinase M2 that were reduced by OGD insult. The HOTTIP overexpression also diminished OGD induced the apoptosis and the caspase-3 activity of neurons. The miR-143 mimic reversed these effects, and anti-miR-143 enhanced them. In addition, we found that HOTTIP could function as a competing endogenous RNA for miR-143 to modulate HK-2 expression. In conclusion, the HOTTIP expression was reduced in ischemic stroke. The HOTTIP overexpression attenuated OGD-induced neuronal injury and imbalanced glycolytic metabolism by sponging miR-143, resulting in the de-repression of its endogenous target HK-2. Taken together, these findings improve understanding of the pathogenesis of ischemic stroke.

Long non-coding RNA, CHRF, predicts poor prognosis of lung adenocarcinoma and promotes cell proliferation and migration

Research has demonstrated that long non-coding RNAs (lncRNAs) are crucial factors in carcinogenesis. LncRNA, cardiac hypertrophy-related factor (CHRF), has been demonstrated to act as an oncogene in a variety of types of tumor. However, its biological function in lung adenocarcinoma remains to be elucidated. The present study aimed to examine the level of CHRF expression in lung adenocarcinoma tissues and cell lines, and to analyze the association between CHRF and clinicopathological characteristics, as well prognosis of patients with lung adenocarcinoma. Loss-of-function assays were performed to determine the biological function of CHRF. The expression of CHRF was markedly upregulated in lung adenocarcinoma tissues and cell lines. Patients exhibiting upregulated CHRF also demonstrated advanced Tumor-Node-Metastasis stage, lymph node metastasis and larger tumor size compared with those exhibiting downregulated CHRF. Results of Cox proportional hazards regression analysis suggested that highly-expressed CHRF may be regarded as an independent prognostic factor of prognosis. In addition, loss-of-function assays indicated that downregulation of CHRF suppressed cell proliferation, migration and invasion, and induced cell cycle arrest and apoptosis. Western blotting revealed that the phosphoinositide-3-kinase/Akt signaling pathway activity is reduced in lung adenocarcinoma following the knockdown of CHRF. Together, these results indicate that lncRNA, CHRF, may serve a critical role in the development and progression of lung adenocarcinoma, and may act as a novel prognostic biomarker and therapeutic target in lung adenocarcinoma.

Connivance, Complicity, or Collusion? The Role of Noncoding RNAs in Promoting Gammaherpesvirus Tumorigenesis

EBV and KSHV are etiologic agents of multiple types of lymphomas and carcinomas. The frequency of EBV⁺ or KSHV⁺ malignancies arising in immunocompromised individuals reflects the intricate evolutionary balance established between these viruses and their immunocompetent hosts. However, the specific mechanisms by which these pathogens drive tumorigenesis remain poorly understood. In recent years an enormous array of cellular and viral noncoding RNAs (ncRNAs) have been discovered, and host ncRNAs have been revealed as contributory factors to every single cancer hallmark cellular process. As new evidence emerges that gammaherpesvirus ncRNAs also alter host processes and viral factors dysregulate host ncRNA expression, and as novel viral ncRNAs continue to be discovered, we examine the contribution of small, non-miRNA ncRNAs and long ncRNAs to gammaherpesvirus tumorigenesis.