Long noncoding RNA LINC00630 promotes radio‐resistance by regulating BEX1 gene methylation in colorectal cancer cells

The construction and experimental verification of a 6-LncRNA model based on Lactic acid metabolism in the tumor microenvironment of Wilms tumor

BACKGROUND

Lactic acid (LA) can promote the malignant progression of tumors through the crosstalk with the tumor microenvironment (TME). However, the function of long non-coding RNAs (lncRNAs) related to LA metabolism in Wilms tumor (WT) remains unclear.

METHODS

Gene expression data and clinical data of WT patients were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Through the ESTIMATE algorithm and Pearson correlation analysis, lncRNAs related to tumor immunity and LA metabolism were screened. Subsequently, Cox regression analysis and Lasso Cox regression analysis were used to construct a model. Furthermore, candidate genes were identified and a competitive endogenous RNA (ceRNA) network was conducted to explore the specific mechanism of characteristic genes. Finally, based on the strong clinical relevance of UNC5B-AS1, its expression and function were experimentally verified.

RESULTS

The immune score and stromal score were found to be closely related to the prognosis of WT. Eventually, a prognostic model (TME-LA-LM) consisting of 6 lncRNAs was successfully identified. The model demonstrated favorable predictive ability and accuracy, with significant variation in immune infiltration and drug susceptibility observed between risk groups. Additionally, the study revealed the involvement of 2 candidate genes and 5 microRNAs (miRNAs) in the tumor's development. Notably, UNC5B-AS1 was highly expressed and found to promote the proliferation and migration of tumor cells.

CONCLUSION

This study, for the first time, elucidated the prognostic signatures of WT using lncRNAs related to TME and LA metabolism. The fundings of this research offer valuable insights for future studies on immunotherapy, personalized chemotherapy and mechanism research.

Unraveling the ncRNA landscape that governs colorectal cancer: A roadmap to personalized therapeutics

Colorectal cancer (CRC) being one of the most common malignancies, has a significant death rate, especially when detected at an advanced stage. In most cases, the fundamental aetiology of CRC remains unclear despite the identification of several environmental and intrinsic risk factors. Numerous investigations, particularly in the last ten years, have indicated the involvement of epigenetic variables in this type of cancer. The development, progression, and metastasis of CRC are influenced by long non-coding RNAs (lncRNAs), which are significant players in the epigenetic pathways. LncRNAs are implicated in diverse pathological processes in CRC, such as liver metastasis, epithelial to mesenchymal transition (EMT), inflammation, and chemo-/radioresistance. It has recently been determined that CRC cells and tissues exhibit dysregulation of tens of oncogenic and tumor suppressor lncRNAs. Serum samples from CRC patients exhibit dysregulated expressions of several of these transcripts, offering a non-invasive method of detecting this kind of cancer. In this review, we outlined the typical paradigms of the deregulated lncRNA which exert significant role in the underlying molecular mechanisms of CRC initiation and progression. We comprehensively discuss the role of lncRNAs as innovative targets for CRC prognosis and treatment.

PTBP1 Regulates DNMT3B Alternative Splicing by Interacting With RALY to Enhance the Radioresistance of Prostate Cancer

Radiotherapy is a curative arsenal for prostate cancer (PCa), but radioresistance seriously compromises its effectiveness. Dysregulated RNA splicing factors are extensively involved in tumor progression. Nonetheless, the role of splicing factors in radioresistance remains largely unexplored in PCa. Here, 23 splicing factors that are differentially expressed between PCa and adjacent normal tissues across multiple public PCa databases are identified. Among those genes, polypyrimidine tract binding protein 1 (PTBP1) is significantly upregulated in PCa and is positively associated with advanced clinicopathological features and poor prognosis. Gain- and loss-of-function experiments demonstrate that PTBP1 markedly reinforces genomic DNA stability to desensitize PCa cells to irradiation in vitro and in vivo. Mechanistically, PTBP1 interacts with the heterogeneous nuclear ribonucleoproteins (hnRNP) associated with lethal yellow protein homolog (RALY) and regulates exon 5 splicing of DNA methyltransferase 3b (DNMT3B) from DNMT3B-S to DNMT3B-L. Furthermore, upregulation of DNMT3B-L induces promoter methylation of dual-specificity phosphatase-2 (DUSP2) and subsequently inhibits DUSP2 expression, thereby increasing radioresistance in PCa. The findings highlight the role of splicing factors in inducing aberrant splicing events in response to radiotherapy and the potential role of PTBP1 and DNMT3B-L in reversing radioresistance in PCa.

DNA repair in tumor radioresistance: insights from fruit flies genetics

BACKGROUND

Radiation therapy (RT) is a key anti-cancer treatment that involves using ionizing radiation to kill tumor cells. However, this therapy can lead to short- and long-term adverse effects due to radiation exposure of surrounding normal tissue. The type of DNA damage inflicted by radiation therapy determines its effectiveness. High levels of genotoxic damage can lead to cell cycle arrest, senescence, and cell death, but many tumors can cope with this damage by activating protective mechanisms. Intrinsic and acquired radioresistance are major causes of tumor recurrence, and understanding these mechanisms is crucial for cancer therapy. The mechanisms behind radioresistance involve processes like hypoxia response, cell proliferation, DNA repair, apoptosis inhibition, and autophagy.

CONCLUSION

Here we briefly review the role of genetic and epigenetic factors involved in the modulation of DNA repair and DNA damage response that promote radioresistance. In addition, leveraging our recent results on the effects of low dose rate (LDR) of ionizing radiation on Drosophila melanogaster we discuss how this model organism can be instrumental in the identification of conserved factors involved in the tumor resistance to RT.

Non-coding RNAs in radiotherapy resistance: Roles and therapeutic implications in gastrointestinal cancer

Radiotherapy has become an indispensable and conventional means for patients with advanced solid tumors including gastrointestinal cancer. However, innate or acquired radiotherapy resistance remains a significant challenge and greatly limits the therapeutic effect, which results in cancer relapse and poor prognosis. Therefore, it is an urgent need to identify novel biomarkers and therapeutic targets for clarify the biological characteristics and mechanism of radiotherapy resistance. Recently, lots of studies have revealed that non-coding RNAs (ncRNAs) are the potential indicators and regulators of radiotherapy resistance via the mediation of various targets/pathways in different cancers. These findings may serve as a potential therapeutic strategy to overcome radiotherapy resistance. In this review, we will shed light on the recent findings regarding the functions and regulatory mechanisms of ncRNAs following radiotherapy, and comprehensively discuss their potential as biomarkers and therapeutic targets in radiotherapy resistance of gastrointestinal cancer.

The exciting encounter between lncRNAs and radiosensitivity in IR-induced DNA damage events

Radiation therapy is a commonly used tool in cancer management due to its ability to destroy malignant tumors. Mechanically, the efficacy of radiotherapy mainly depends on the inherent radiosensitivity of cancer cells and surrounding normal tissues, which mostly accounts for molecular dynamics associated with radiation-induced DNA damage. However, the relationship between radiosensitivity and DNA damage mechanism deserves to be further probed. As the well-established RNA regulators or effectors, long noncoding RNAs (lncRNAs) dominate vital roles in modulating ionizing radiation response by targeting crucial molecular pathways, including DNA damage repair. Recently, emerging evidence has constantly confirmed that overexpression or inhibition of lncRNAs can greatly influence the sensitivity of radiotherapy for many kinds of cancers, by driving a diverse array of DNA damage-associated signaling cascades. In conclusion, this review critically summarizes the recent progress in the molecular mechanism of IR-responsive lncRNAs in the context of radiation-induced DNA damage. The different response of lncRNAs when IR exposure. IR exposure can trigger the changes in expression pattern and subcellular localization of lncRNAs that influences the different radiology processes.

The Prognostic Value of a lncRNA Risk Model Consists of 9 m6A Regulator-Related lncRNAs in Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver. Although the RNA modification N6-methyladenine (m6A) has been reported to be involved in HCC carcinogenesis, early diagnostic markers and promising personalized therapeutic targets are still lacking. In this study, we identified that 19 m6A regulators and 34 co-expressed lncRNAs were significantly upregulated in HCC samples; based on these factors, we established a prognostic signal of HCC associated with 9 lncRNAs and 19 m6A regulators using LASSO Cox regression analysis. Kaplan-Meier survival estimate revealed correlations between the risk scores and patients' OS in the training and validation dataset. The ROC curve demonstrated that the risk score-based curve has satisfactory prediction efficiency for both training and validation datasets. Multivariate Cox's proportional hazard regression analysis indicated that the risk score was an independent risk factor within the training and validation dataset. In addition, the risk score could distinguish HCC patients from normal non-cancerous samples and HCC samples of different pathological grades. Eventually, 232 mRNAs were co-expressed with these 9 lncRNAs according to GSE101685 and GSE112790; these mRNAs were enriched in cell cycle and cell metabolic activities, drug metabolism, liver disease-related pathways, and some important cancer related pathways such as p53, MAPK, Wnt, RAS and so forth. The expression of the 9 lncRNAs was significantly higher in HCC samples than that in the neighboring non-cancerous samples. Altogether, by using the Consensus Clustering, PCA, ESTIMATE algorithm, LASSO regression model, Kaplan-Meier survival assessment, ROC curve analysis, and multivariate Cox's proportional hazard regression model analysis, we established a prognostic marker consisting of 9 m6A regulator-related lncRNAs that markers may have prognostic and diagnostic potential for HCC.

Insights into the role of long non-coding RNAs in DNA methylation mediated transcriptional regulation

DNA methylation is one of the most important epigenetic mechanisms that governing regulation of gene expression, aberrant DNA methylation patterns are strongly associated with human malignancies. Long non-coding RNAs (lncRNAs) have being discovered as a significant regulator on gene expression at the epigenetic level. Emerging evidences have indicated the intricate regulatory effects between lncRNAs and DNA methylation. On one hand, transcription of lncRNAs are controlled by the promoter methylation, which is similar to protein coding genes, on the other hand, lncRNA could interact with enzymes involved in DNA methylation to affect the methylation pattern of downstream genes, thus regulating their expression. In addition, circular RNAs (circRNAs) being an important class of noncoding RNA are also found to participate in this complex regulatory network. In this review, we summarize recent research progress on this crosstalk between lncRNA, circRNA, and DNA methylation as well as their potential functions in complex diseases including cancer. This work reveals a hidden layer for gene transcriptional regulation and enhances our understanding for epigenetics regarding detailed mechanisms on lncRNA regulatory function in human cancers.

Role of non-coding RNAs in radiosensitivity of colorectal cancer: A narrative review

Colorectal cancer (CRC) is a global public health concern because of its high prevalence and mortality. Although radiotherapy is a key method for treating CRC, radioresistance is an obstacle to radiotherapy use. The molecular mechanisms underlying the radioresistance of CRC remain unclear. Increasing evidence has revealed the multiple regulatory functions of non-coding RNAs (ncRNAs) in numerous malignancies, including CRC. Several ncRNAs have been reported to be involved in the determination of radiosensitivity of CRC cells, and some have excellent potential to be prognostic biomarkers or therapeutic targets in CRC treatment. The present review discusses the biological functions and underlying mechanisms of ncRNAs (primarily lncRNA, miRNA, and circRNA) in the regulation of the radiosensitivity of CRC. We also evaluate studies that examined ncRNAs as biomarkers of response to radiation and as therapeutic targets for enhancing radiosensitivity.

LncRNAs as Theragnostic Biomarkers for Predicting Radioresistance in Cancer: A Systematic Review and Meta-Analysis

Background

Radioresistance is the major obstacle after cancer radiotherapy. The dysregulation of long non-coding RNAs (lncRNAs) was closely related the radioresistance response. This meta-analysis was aimed to interpret the relationship between lncRNAs and radiotherapy responses in different cancers.

Method

The studies were selected from databases including PubMed, ISI Web of Science, Embase, Google Scholar, PMC, and CNKI (China National Knowledge Infrastructure). The publication time was limited to before March 20, 2021. The hazard ratios (HRs) and 95% confidence interval were calculated with random-effects models. Subgroup analyses, sensitivity analyses, and publication bias were also conducted.

Result

Twenty-seven lncRNAs in 14 cancer types were investigated, in which 23 lncRNAs were upregulated and four lncRNAs were downregulated. Dysregulation of these lncRNAs were found to be related to radioresistance response. The pooled HR and 95% confidence interval for the combined up-regulated lncRNAs was 1.73 (95% CI=1.50-2.00; P< 0.01) and down-regulated lncRNAs was 2.09 (95% CI= 1.60-2.72; P< 0.01). The HR values of the subgroup analysis for glioma (HR= 2.22, 95% CI= 1.79-2.74; p< 0.01), non-small cell lung cancer (HR=1.48, 95% CI=1.18-1.85; P<0.01), nasopharyngeal carcinoma (HR=4.26; 95% CI= 1.58-11.46; P< 0.01), and breast cancer (HR=1.29; 95% CI= 1.08-1.54; P< 0.01) were obtained. Moreover, the expression of lncRNAs was significantly related to overall survival of patients no matter if the sample size was >50 or not. In addition, the HR values of the subgroup analysis for lncRNA H19 (HR=2.68; 95% CI= 1.92-3.74; P <0.01), lncRNA FAM201A (HR=2.15; 95% CI= 1.15-3.99; P <0.01), and lncRNA HOTAIR (HR=1.22; 95% CI= 0.98-1.54; P =0.08) were also obtained.

Conclusion

LncRNAs can induce cancer radioresistance by regulating cell death-related signaling pathways. Results indicated that lncRNAs, especially lncRNA H19, FAM201A, and HOTAIR, could be considered as a predictive theragnostic biomarker to evaluate radiotherapy response.

Recent advances in targeted drug delivery systems for resistant colorectal cancer

Colorectal cancer (CRC) is one of the deadliest cancers in the world, the incidences and morality rate are rising and poses an important threat to the public health. It is known that multiple drug resistance (MDR) is one of the major obstacles in CRC treatment. Tumor microenvironment plus genomic instability, tumor derived exosomes (TDE), cancer stem cells (CSCs), circulating tumor cells (CTCs), cell-free DNA (cfDNA), as well as cellular signaling pathways are important issues regarding resistance. Since non-targeted therapy causes toxicity, diverse side effects, and undesired efficacy, targeted therapy with contribution of various carriers has been developed to address the mentioned shortcomings. In this paper the underlying causes of MDR and then various targeting strategies including exosomes, liposomes, hydrogels, cell-based carriers and theranostics which are utilized to overcome therapeutic resistance will be described. We also discuss implication of emerging approaches involving single cell approaches and computer-aided drug delivery with high potential for meeting CRC medical needs.

Potentials of long non-coding RNAs as biomarkers of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant tumor worldwide and the fourth major cause of cancer-related death, with high morbidity and increased mortality year by year. Although significant progress has been made in the therapy strategies for CRC, the great difficulty in early diagnosis, feeble susceptibility to radiotherapy and chemotherapy, and high recurrence rates have reduced therapeutic efficacy resulting in poor prognosis. Therefore, it is urgent to understand the pathogenesis of CRC and unravel novel biomarkers to improve the early diagnosis, treatment and prediction of CRC recurrence. Long non-coding RNAs (lncRNAs) are non-coding RNAs with a length of more than 200 nucleotides, which are abnormally expressed in tumor tissues and cell lines, activating or inhibiting specific genes through multiple mechanisms including transcription and translation. A growing number of studies have shown that lncRNAs are important regulators of microRNAs (miRNAs, miRs) expression in CRC and may be promising biomarkers and potential therapeutic targets in the research field of CRC. This review mainly summarizes the potential application value of lncRNAs as novel biomarkers in CRC diagnosis, radiotherapy, chemotherapy and prognosis. Additionally, the significance of lncRNA SNHGs family and lncRNA-miRNA networks in regulating the occurrence and development of CRC is mentioned, aiming to provide some insights for understanding the pathogenesis of CRC and developing new diagnostic and therapeutic strategies.

LncRNA-mediated DNA methylation: an emerging mechanism in cancer and beyond

DNA methylation is one of the most important epigenetic mechanisms to regulate gene expression, which is highly dynamic during development and specifically maintained in somatic cells. Aberrant DNA methylation patterns are strongly associated with human diseases including cancer. How are the cell-specific DNA methylation patterns established or disturbed is a pivotal question in developmental biology and cancer epigenetics. Currently, compelling evidence has emerged that long non-coding RNA (lncRNA) mediates DNA methylation in both physiological and pathological conditions. In this review, we provide an overview of the current understanding of lncRNA-mediated DNA methylation, with emphasis on the roles of this mechanism in cancer, which to the best of our knowledge, has not been systematically summarized. In addition, we also discuss the potential clinical applications of this mechanism in RNA-targeting drug development.

DNMT1-mediated methylation of BEX1 regulates stemness and tumorigenicity in liver cancer

BACKGROUND & AIMS

Hepatoblastoma (HB) and hepatocellular carcinoma (HCC) both exhibit notable cancer stem cell (CSC) features. Moreover, the development of both diseases is closely associated with the presence of CSCs. We investigated the role of brain-expressed X-linked protein 1 (BEX1) in regulating the CSC properties of HB and a subtype of HCC with high CSC features (CSC-HCC).

METHODS

Stemness scores were analyzed in 5 murine HCC models. A subpopulation of BEX1-positive cells and BEX1-negative cells were sorted from HCC cell lines, and subjected to transcriptome analysis. The expression and function of BEX1 was examined via western blotting, sphere formation assays, and xenograft tumor models.

RESULTS

We identified BEX1 as a novel CSC marker that was required for the self-renewal of liver CSCs. Furthermore, zebularine, a potent DNMT1 inhibitor, can induce the reactivation of BEX1 by removing epigenetic inhibition. Notably, BEX1 was highly expressed in patients with HB and CSC-HCC, but not in patients with non-CSC HCC. Moreover, DNMT1-mediated methylation of the BEX1 promoter resulted in differential BEX1 expression patterns in patients with HB, CSC-HCC, and non-CSC-HCC. Mechanistically, BEX1 interacted with RUNX3 to block its inhibition of β-catenin transcription, which led to the activation of Wnt/β-catenin signaling, and stemness maintenance in both HB and CSC-HCC. In contrast, downregulated BEX1 expression released RUNX3 and inhibited the activation of Wnt/β-catenin signaling in non-CSC-HCC.

CONCLUSION

BEX1, under the regulation of DNMT1, is necessary for the self-renewal and maintenance of liver CSCs through activation of Wnt/β-catenin signaling, rendering BEX1 a potentially valuable therapeutic target in both HB and CSC-HCC.

LAY SUMMARY

Cancer stem cells (CSCs) contribute to a high rate of cancer recurrence, as well as resistance to conventional therapies. However, the regulatory mechanisms underlying their self-renewal remains elusive. Herein, we have reported that BEX1 plays a key role in regulating CSC properties in different types of liver cancer. Targeting BEX1-mediated Wnt/β-catenin signaling may help to address the high rate of recurrence, and heterogeneity of liver cancer.

Long non-coding RNA LINC00630 facilitates hepatocellular carcinoma progression through recruiting transcription factor E2F1 to up-regulate cyclin-dependent kinase 2 expression

This study is aimed to investigate the role of long non-coding RNA 630 (LINC00630) in hepatocellular carcinoma (HCC). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine LINC00630 expression in HCC cell lines and tissues. After LINC00630 was overexpressed or depleted in HCC cell lines, cell counting kit-8 (CCK-8) assay, BrdU assay, and flow cytometry were conducted for detecting HCC cell multiplication, apoptosis, and cell cycle progression. The catRAPID database was adopted to predict the binding relationship between LINC00630 and E2F transcription factor 1 (E2F1), and RNA pull-down and RNA immunoprecipitation (RIP) assays were carried out to verify this binding relationship. The binding of E2F1 to the cyclin-dependent kinase 2 (CDK2) promoter region was verified by dual-luciferase reporter gene assay and chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR) assay. Western blotting was conducted to detect the protein expression of E2F1 and CDK2 in HCC cells. We report that LINC00630 expression was up-regulated in HCC and was significantly correlated with TNM stage and lymph node metastasis. LINC00630 overexpression facilitated HCC cell proliferation and cell cycle progression and inhibited the cell apoptosis, while LINC00630 knockdown had the opposite effects. LINC00630 directly bounds with E2F1. LINC00630 overexpression enhanced the binding of E2F1 to the CDK2 promoter region, thereby promoting CDK2 transcription, whereas knocking down LINC00630 inhibited CDK2 transcription. Collectively, LINC00630 promoted CDK2 transcription by recruiting E2F1 to the promoter region of CDK2, thereby promoting the malignant progression of HCC. Our data suggest that LINC00630 is a promising molecular target for HCC.

Regulatory Non-coding RNAs for Death Associated Protein Kinase Family

The death associated protein kinases (DAPKs) are a family of calcium dependent serine/threonine kinases initially identified in the regulation of apoptosis. Previous studies showed that DAPK family members, including DAPK1, DAPK2 and DAPK3 play a crucial regulatory role in malignant tumor development, in terms of cell apoptosis, proliferation, invasion and metastasis. Accumulating evidence has demonstrated that non-coding RNAs, including microRNA (miRNA), long non-coding RNA (lncRNA) and circRNA, are involved in the regulation of gene expression and tumorigenesis. Recent studies indicated that non-coding RNAs participate in the regulation of DAPKs. In this review, we summarized the current knowledge of non-coding RNAs, as well as the potential miRNAs, lncRNAs and circRNAs, that are involved in the regulation of DAPKs.

Identification of a nomogram based on an 8-lncRNA signature as a novel diagnostic biomarker for childhood acute lymphoblastic leukemia

Childhood acute lymphoblastic leukemia (cALL) still represents a major cause of disease-related death in children. This study aimed to explore the prognostic value of long non-coding RNAs (lncRNAs) in cALL. We downloaded lncRNA expression profiles from the TARGET and GEO databases. Univariate, least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analyses were applied to identify lncRNA-based signatures. We identified an eight-lncRNA signature (LINC00630, HDAC2-AS2, LINC01278, AL356599.1, AC114490.1, AL132639.3, FUT8.AS1, and TTC28.AS1), which separated the patients into two groups with significantly different overall survival rates. A nomogram based on the signature, BCR ABL1 status and white blood cell count at diagnosis was developed and showed good accuracy for predicting the 3-, 5- and 7-year survival probability of cALL patients. The C-index values of the nomogram in the training and internal validation set reached 0.8 (95% CI, 0.757 to 0.843) and 0.806 (95% CI, 0.728 to 0.884), respectively. The nomogram proposed in this study objectively and accurately predicted the prognosis of cALL. In vitro experiments suggested that LINC01278 promoted the proliferation of leukemic cells and inhibited leukemic cell apoptosis by targeting the inhibition of miR-500b-3p in cALL, and LINC01278 may be a biological target for the treatment of cALL in the future.

Deciphering the epigenetic network in cancer radioresistance

Radiotherapy, in addition to surgery and systemic chemotherapy, remains the core of the current clinical management of cancer. Radioresistance is one of the major causes of disease progression and mortality in cancer; therefore, it is a significant challenge in the treatment of locally advanced, recurrent and metastatic cancer. Epigenetic mechanisms that control hallmarks of cancer have a key role in the development of radiation resistance of cancer cells. Recent advances in DNA methylation, histone modification, chromatin remodeling and non-coding RNAs identified in the control of signal transduction pathways in cancer and cancer stem cells have provided even greater promise in the improvement of understanding cancer radioresistance. Many epigenetic drugs that target epigenetic enzymes revert the radioresistant phenotypes decreasing the possibility that resistant cancer cells will develop refractory tumors to radiotherapy. Epigenetic profiles identified as regulators of DNA damage repair, hypoxia, cell survival, apoptosis and invasion are determinants in the development of tumor radioresistance; hence, they also are promising in personalized medicine to develop novel targeted therapies or biomarkers to follow-up the effectiveness of radiotherapy. Now, it is clear that radiotherapy can influence a complex epigenetic network for transcriptional reprogramming, enabling the cells to adapt and avoid the effect of radiotherapy. This review aims to highlight the epigenetic modifications identified in cancer radioresistance and to discuss approaches to disable epigenetic networks to increase the sensitivity and specificity of radiotherapy.

Long Noncoding RNA LINC00526 Represses Glioma Progression via Regulating miR-5581-3p/BEX1

The roles of long noncoding RNAs (lncRNAs) in regulating glioma progression have been widely recognized in recent years. This work was to investigate the roles and associated mechanisms of LINC00526 in glioma progression. LINC00526 expression in glioma tissues and cells and their normal counterparts was measured with quantitative real-time polymerase chain reaction method. Functions of LINC00526 in glioma were investigated with in vitro experiments. Moreover, competitive RNA (ceRNA) theory was employed to understand mechanisms of action of LINC00526 in glioma. LINC00526 was found to be decreased in glioma tissues and cell lines compared with their normal counterparts. Silencing the expression of LINC00526 promotes, while forcing its expression, inhibits glioma cell growth and invasion. Mechanism analyses showed LINC00526 functions as a sponge for microRNA-5581-3p (miR-5581-3p) to regulate brain-expressed X-linked 1 (BEX1) expression and, in the end, affects glioma progression. Collectively, our study indicated LINC00526 serves as a tumor-suppressive lncRNA and directly regulates miR-5581-3p/BEX1 axis in glioma.

Emerging role of non-coding RNAs in response of cancer cells to radiotherapy

Radiotherapy is an effective method for treatment of a large proportion of human cancers. Yet, the efficacy of this method is precluded by the induction of radioresistance in tumor cells and the radiation-associated injury of normal cells surrounding the field of radiation. These restrictions necessitate the introduction of modalities for either radiosensitization of cancer cells or protection of normal cells against adverse effects of radiation. Non-coding RNAs (ncRNAs) have essential roles in the determination of radiosensitivity. Moreover, ncRNAs can modulate radiation-induced side effects in normal cells. Several microRNAs (miRNAs) such as miR-620, miR-21 and miR-96-5p confer radioresistance, while other miRNAs including miR-340/ 429 confer radiosensitivity. The expression levels of a number of miRNAs are associated with radiation-induced complications such as lung fibrosis or oral mucositis. The expression patterns of several long non-coding RNAs (lncRNAs) such as MALAT1, LINC00630, HOTAIR, UCA1 and TINCR are associated with response to radiotherapy. Taken together, lncRNAs and miRNAs contribute both in modulation of response of cancer cells to radiotherapy and in protection of normal cells from the associated side effects. The current review provides an overview of the roles of these transcripts in these aspects.