Colon Cancer-Associated Transcripts 1 and 2: Roles and functions in human cancers

Targeting long non-coding RNAs in cancer therapy using CRISPR-Cas9 technology: A novel paradigm for precision oncology

Cancer is the second leading cause of death worldwide, despite recent advances in its identification and management. To improve cancer patient diagnosis and care, it is necessary to identify new biomarkers and molecular targets. In recent years, long non-coding RNAs (lncRNAs) have surfaced as important contributors to various cellular activities, with growing proof indicating their substantial role in the genesis, development, and spread of cancer. Their unique expression profiles within specific tissues and their wide-ranging functionalities make lncRNAs excellent candidates for potential therapeutic intervention in cancer management. They are implicated in multiple hallmarks of cancer, such as uncontrolled proliferation, angiogenesis, and immune evasion. This review article explores the innovative application of CRISPR-Cas9 technology in targeting lncRNAs as a cancer therapeutic strategy. The CRISPR-Cas9 system has been widely applied in functional genomics, gene therapy, and cancer research, offering a versatile platform for lncRNA targeting. CRISPR-Cas9-mediated targeting of lncRNAs can be achieved through CRISPR interference, activation or the complete knockout of lncRNA loci. Combining CRISPR-Cas9 technology with high-throughput functional genomics makes it possible to identify lncRNAs critical for the survival of specific cancer subtypes, opening the door for tailored treatments and personalised cancer therapies. CRISPR-Cas9-mediated lncRNA targeting with other cutting-edge cancer therapies, such as immunotherapy and targeted molecular therapeutics can be used to overcome the drug resistance in cancer. The synergy of lncRNA research and CRISPR-Cas9 technology presents immense potential for individualized cancer treatment, offering renewed hope in the battle against this disease.

Role of lncRNAs in Helicobacter pylori and Epstein-Barr virus associated gastric cancers

Helicobacter pylori infection is a risk factor for the development of gastric cancer (GC), and the role of co-infection with viruses, such as Epstein-Barr virus, in carcinogenesis cannot be ignored. Furthermore, it is now known that genetic factors such as long non-coding RNAs (lncRNAs) are involved in many diseases, including GC. On the other side, they can also be used as therapeutic goals. Modified lncRNAs can cause aberrant expression of genes encoding proximal proteins, which are essential for the development of carcinoma. In this review, we present the most recent studies on lncRNAs in GC, concentrating on their roles in H. pylori and EBV infections, and discuss some of the molecular mechanisms of these GC-related pathogens. There was also a discussion of the research gaps and future perspectives.

lncRNA CCAT2 Protects Against Cardiomyocyte Injury After Myocardial Ischemia/Reperfusion by Regulating BMI1 Expression

Myocardial ischemia/reperfusion (I/R) decreases cardiac function and efficiency. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) have been linked to the cellular processes of myocardial I/R injury. The present investigation elucidated the function of lncRNA colon cancer-associated transcript 2 (CCAT2) in myocardial I/R injury and the related mechanisms.AC16 cardiomyocytes were exposed to hypoxia (16 hours) /reoxygenation (6 hours) (H/R) to mimic myocardial I/R models in vitro. CCAT2 and microRNA (miR) -539-3p expressions in AC16 cardiomyocytes were measured using real-time quantitative polymerase chain reaction. B-cell-specific Moloney murine leukemia virus insertion region 1 (BMI1) protein levels in AC16 cardiomyocytes were determined by western blotting. Cell viability, lactate dehydrogenase (LDH) leakage, reactive oxygen species (ROS) levels, mitochondrial membrane potential, and apoptosis were detected using Counting Kit-8, LDH Assay Kit, dihydroethidium assay, 5,5',6,6'-tetrachloro1,1',3,3'-tetramethylbenzimidazolylcarbocyanine iodide staining, flow cytometry, and western blotting, respectively. The interactions between the molecules were confirmed using the dual-luciferase gene reporter. The wingless/integrated/beta-catenin (Wnt/β-catenin) pathway under the H/R condition was detected by western blotting.CCAT2 and BMI1 mRNA expressions were reduced in H/R-exposed AC16 cardiomyocytes. CCAT2 overexpression exerted protective effects against H/R-induced cardiomyocyte injury, as demonstrated by increased cell viability and mitochondrial membrane potential and decreased LDH leakage, ROS levels, and apoptosis. In addition, CCAT2 positively regulated BMI1 expression by binding to miR-539-3p. CCAT2 knockdown or miR-539-3p overexpression restrained the protective effects of BMI1 against H/R-induced cardiomyocyte injury. In addition, miR-539-3p overexpression reversed the protective effects of CCAT2. Furthermore, CCAT2 activated the Wnt/β-catenin pathway under the H/R condition via the miR-539-3p/BMI1 axis.Overall, this investigation showed the protective effects of the CCAT2/miR-539-3p/BMI1/Wnt/β-catenin regulatory axis against cardiomyocyte injury induced by H/R.

Noncoding RNA mutations in cancer

Cancer is driven by both germline and somatic genetic changes. Efforts have been devoted to characterizing essential genetic variations in cancer initiation and development. Most attention has been given to mutations in protein-coding genes and associated regulatory elements such as promoters and enhancers. The development of sequencing technologies and in silico and experimental methods has allowed further exploration of cancer predisposition variants and important somatic mutations in noncoding RNAs, mainly for long noncoding RNAs and microRNAs. Association studies including GWAS have revealed hereditary variations including SNPs and indels in lncRNA or miRNA genes and regulatory regions. These mutations altered RNA secondary structures, expression levels, and target recognition and then conferred cancer predisposition to carriers. Whole-exome/genome sequencing comparing cancer and normal tissues has revealed important somatic mutations in noncoding RNA genes. Mutation hotspots and somatic copy number alterations have been identified in various tumor-associated noncoding RNAs. Increasing focus and effort have been devoted to studying the noncoding region of the genome. The complex genetic network of cancer initiation is being unveiled. This article is categorized under: RNA in Disease and Development > RNA in Disease.

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.

Clinicopathological and prognostic value of long non-coding RNA CCAT1 expression in patients with digestive system cancer

Colon cancer associated transcript-1 (CCAT1) is known to play an important role in numerous types of human cancer, including bladder, prostate and ovarian cancer. However, a consistent perspective has not been established in digestive system cancer (DSC). To explore the prognostic value of CCAT1 in patients with DSC, a meta-analysis was performed. A systematic search of PubMed, Embase, Web of Science, China National Knowledge Infrastructure, Chinese Biological Medical Literature database, Cochrane Library and WanFang database was applied to select eligible articles. Pooled odds ratios (ORs) or hazard ratios (HRs) with corresponding 95% confidence intervals (CIs) were calculated to estimate the effects of CCAT1 on pathological or clinical features. A total of 1,719 patients from 12 eligible articles were enrolled in the meta-analysis. The results revealed that elevated CCAT1 expression was significantly related to larger tumor size (OR, 1.81; 95% CI, 1.31-2.48), poorer differentiation (OR, 0.45; 95% CI, 0.31-0.64), earlier lymph node metastasis (OR, 3.14; 95% CI, 2.34-4.22) and advanced TNM stage (OR, 3.08; 95% CI, 2.07-4.59). In addition, high CCAT1 expression predicted a poorer outcome for overall survival rate (HR, 2.37; 95% CI, 2.11-2.67) and recurrence-free survival rate (HR, 2.16, 95% CI, 1.31-3.57). High expression levels of CCAT1 were therefore related to unfavorable clinical outcomes of patients with DSC. These results demonstrated that CCAT1 could serve as a prognostic predictor in human DSC.

A review on the role of NR2F1-AS1 in the development of cancer

NR2F1-AS1 is a natural antisense transcript with prominent roles in the carcinogenesis. It acts as an oncogene in almost all types of cancers except for cervical and colorectal cancers. It can act as a molecular sponge for miR-17, miR-371a-3p, miR-363, miR-29a-3p, miR-493-5p, miR-190a, miR-140, miR-642a, miR-363, miR-493-5p, miR-483-3p, miR-485-5p, miR-146a-5p, miR-877-5p, miR-338-3 P and miR-423-5p to influence expression of several cancer-related genes. Thus, the sponging role of NR2F1-AS1 is the most appreciated route of its contribution in the carcinogenesis. In addition, NR2F1-AS1 affects activity of IGF-1/IGF-1R/ERK, PI3K/AKT/GSK-3β and Hedgehog pathways. The current narrative review aims at summarization of the results of studies that highlighted the role of NR2F1-AS1 in the carcinogenesis.

Long-read sequencing unveils high-resolution HPV integration and its oncogenic progression in cervical cancer

Integration of human papillomavirus (HPV) DNA into the human genome is considered as a key event in cervical carcinogenesis. Here, we perform comprehensive characterization of large-range virus-human integration events in 16 HPV16-positive cervical tumors using the Nanopore long-read sequencing technology. Four distinct integration types characterized by the integrated HPV DNA segments are identified with Type B being particularly notable as lacking E6/E7 genes. We further demonstrate that multiple clonal integration events are involved in the use of shared breakpoints, the induction of inter-chromosomal translocations and the formation of extrachromosomal circular virus-human hybrid structures. Combined with the corresponding RNA-seq data, we highlight LINC00290, LINC02500 and LENG9 as potential driver genes in cervical cancer. Finally, we reveal the spatial relationship of HPV integration and its various structural variations as well as their functional consequences in cervical cancer. These findings provide insight into HPV integration and its oncogenic progression in cervical cancer.

The molecular mechanisms underlying cervical carcinogenesis following integration of HPV DNA into the human genome remain elusive. Here, the authors perform long-read sequencing in 16 HPV16-positive cervical tumors and identify distinct integration types, structural variations and potential driver genes.

A stem cell marker KLF5 regulates CCAT1 via three-dimensional genome structure in colorectal cancer cells

BACKGROUND

KLF5 plays a crucial role in stem cells of colorectum in cooperation with Lgr5 gene. In this study, we aimed to explicate a regulatory mechanism of the KLF5 gene product from a view of three-dimensional genome structure in colorectal cancer (CRC).

METHODS

In vitro engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP)-seq method was used to identify the regions that bind to the KLF5 promoter.

RESULTS

We revealed that the KLF5 promoter region interacted with the KLF5 enhancer region as well as the transcription start site (TSS) region of the Colon Cancer Associated Transcript 1 (CCAT1) gene. Notably, the heterodeletion mutants of KLF5 enhancer impaired the cancer stem-like properties of CRC cells. The KLF5 protein participated in the core-regulatory circuitry together with co-factors (BRD4, MED1, and RAD21), which constructs the three-dimensional genome structures consisting of KLF5 promoter, enhancer and CCAT1 TSS region. In vitro analysis indicated that KLF5 regulated CCAT1 expression and we found that CCAT1 expression was highly correlated with KLF5 expression in CRC clinical samples.

CONCLUSIONS

Our data propose the mechanistic insight that the KLF5 protein constructs the core-regulatory circuitry with co-factors in the three-dimensional genome structure and coordinately regulates KLF5 and CCAT1 expression in CRC.

What is beyond LncRNAs in breast cancer: A special focus on colon cancer-associated Transcript-1 (CCAT-1)

Long non-coding RNAs (LncRNAs) play a vital role in the process of malignant transformation. In breast cancer (BC), lncRNAs field is currently under intensive investigations. Yet, the role of lncRNAs as promising diagnostic and/or prognostic biomarkers and as therapeutic target/tool among BC patients still needs a special focus from the biomedical scientists. In BC, triple negative breast cancer patients (TNBC) are the unlucky group as they are always represented with the worst prognosis and the highest mortality rates. For that reason, a special focus on TNBC and associated lncRNAs was addressed in this review. Colon cancer-associated transcript 1 (CCAT-1) is a newly discovered oncogenic lncRNA that has been emerged as a vital biomarker for diagnosis, prognosis and therapeutic interventions in multiple malignancies and showed differential expression among TNBC patients. In this review, the authors shed the light onto the general role of lncRNAs in BC and the specific functional activities, molecular mechanisms, competing endogenous ncRNA role of CCAT-1 in TNBC.

The Role of lncRNAs in Regulating the Intestinal Mucosal Mechanical Barrier

lncRNA is a transcript that is more than 200 bp in length. Currently, evidence has shown that lncRNA is of great significance in cell activity, involved in epigenetics, gene transcription, chromatin regulation, etc. The existence of an intestinal mucosal mechanical barrier hinders the invasion of pathogenic bacteria and toxins, maintaining the stability of the intestinal environment. Serious destruction or dysfunction of the mechanical barrier often leads to intestinal diseases. This review first summarizes the ability of lncRNAs to regulate the intestinal mucosal mechanical barrier. We then discussed how lncRNAs participate in various intestinal diseases by regulating the intestinal mucosal mechanical barrier. Finally, we envision its potential as a new marker for diagnosing and treating intestinal inflammatory diseases.

The Roles of the Colon Cancer Associated Transcript 2 (CCAT2) Long Non-Coding RNA in Cancer: A Comprehensive Characterization of the Tumorigenic and Molecular Functions

Colon cancer-associated transcript 2 (CCAT2) is an intensively studied lncRNA with important regulatory roles in cancer. As such, cumulative studies indicate that CCAT2 displays a high functional versatility due to its direct interaction with multiple RNA binding proteins, transcription factors, and other species of non-coding RNA, especially microRNA. The definitory mechanisms of CCAT2 are its role as a regulator of the TCF7L2 transcription factor, enhancer of MYC expression, and activator of the WNT/β-catenin pathway, as well as a role in promoting and maintaining chromosome instability through the BOP1–AURKB pathway. Additionally, we highlight how the encompassing rs6983267 SNP has been shown to confer CCAT2 with allele-specific functional and structural particularities, such as the allelic-specific reprogramming of glutamine metabolism. Additionally, we emphasize CCAT2’s role as a competitive endogenous RNA (ceRNA) for multiple tumor suppressor miRNAs, such as miR-4496, miR-493, miR-424, miR-216b, miR-23b, miR-34a, miR-145, miR-200b, and miR-143 and the pro-tumorigenic role of the altered regulatory axis. Additionally, due to its upregulation in tumor tissues, wide distribution across cancer types, and presence in serum samples, we outline CCAT2’s potential as a biomarker and disease indicator and its implications for the development of resistance against current cancer therapy regiments and metastasis.

CCAT2 enhances autophagy-related invasion and metastasis via regulating miR-4496 and ELAVL1 in hepatocellular carcinoma

Autophagy is thought to contribute to the pathogenesis of many diseases, including cancer. Long non‐coding RNA (lncRNA) CCAT2 functions as an oncogene in a variety of tumours. However, it is still unknown whether CCAT2 is involved in autophagy and metastasis of hepatocellular carcinoma (HCC). In our study, we found that lncRNA CCAT2 expression was significantly increased in HCC tissue and was correlated with advanced stage and venous invasion. Further experiments revealed that CCAT2 induced autophagy and promoted migration and invasion in vitro and in vivo. Mechanistic investigations found that CCAT2 involved in HCC by regulating miR‐4496/Atg5 in cytoplasm. In nucleus, CCAT2 bound with ELAVL1/HuR to facilitate HCC progression. Our findings suggest that CCAT2 is an oncogenic factor in the progression of HCC with different regulatory mechanisms and may serve as a target for HCC therapy.

Extended transcriptome analysis reveals genome-wide lncRNA-mediated epigenetic dysregulation in colorectal cancer

It is estimated that the rate of epigenetic changes may be orders of magnitude higher than that of genetic changes and that purely epigenetic mechanisms may explain why cancers arise with few or no recurrent mutations. However, supporting evidence remains limited, partly due to the cost of experimentally studying genome-wide epigenetic dysregulation. Since genome modification enzymes are recruited by long noncoding RNAs (lncRNAs) to specific genomic sites, analyzing differentially expressed genes and differentially methylated regions (DMRs) at the DNA binding sites of differentially expressed lncRNAs is important for uncovering epigenetic dysregulation. We performed RNA-seq and MeDIP-seq on a set of colorectal cancer (CRC) and normal colon samples and developed an analysis pipeline for combined analyses of gene expression, DNA methylation, and lncRNA/DNA binding. The genes identified in our data and important for CRC agree with widely reported findings. We found that aberrantly transcribed noncoding transcripts may epigenetically dysregulate genes, that correlated gene expression is significantly determined by epigenetic dysregulation, that differentially expressed noncoding transcripts and their epigenetic targets form distinct modules in different cancer cells, and that many hub lncRNAs in these modules are primate-specific. These results suggest that lncRNA-mediated epigenetic dysregulation greatly determines aberrant gene expression and that epigenetic dysregulation is highly species-specific. The analysis pipeline can effectively unveil cancer- and cell-specific modules of epigenetic dysregulation, and such modules may provide novel clues for identifying diagnostic, therapeutic, and prognostic targets for epigenetic dysregulation.

Variant in BCAR4 gene correlated with the breast cancer susceptibility and mRNA expression of lncRNA BCAR4 in Chinese Han population

BACKGROUND

Long non-coding RNA (LncRNA) Breast cancer anti-estrogen resistance 4 (BCAR4) has been shown to participate in the biological progress of various cancers including breast cancer. Genetic Polymorphisms in BCAR4 may have an influence on the progress of breast cancer, but it is rarely studied.

METHODS

In our epidemiology study, three tagging SNPs (rs4561483, rs11649623 and rs13334967) in lncRNA BCAR4 were selected for genotyping among 487 breast cancer cases and 489 healthy controls. And quantitative real-time PCR (qRT-PCR) was performed to evaluate the relative mRNA expression of BCAR4 in different genotypes of the significant locus rs13334967.

RESULTS

We found that BCAR4 rs13334967 is associated with lower breast cancer risk both in codominant model (AT vs AA, OR 0.632, 95% CI 0.429-0.931, TT vs AA, OR 0.731, 95% CI 0.511-0.990) and dominant model (AT + TT vs AA, OR 0.798, 95% CI 0.571-0.970). The further results of qRT-PCR displayed that carriers with rs13334967 AT, TT genotype have lower BCAR4 mRNA expression compared with AA genotype.

CONCLUSION

The research study implied that BCAR4 rs13334967 was correlated with the susceptibility to breast cancer and may impact the mRNA expression of BCAR4. LncRNA BCAR4 may be a potential biomarker and therapeutic target for breast cancer.

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.

An updated review of the H19 lncRNA in human cancer: molecular mechanism and diagnostic and therapeutic importance

Accumulating evidence has reported that H19 long non-coding RNA (lncRNA) expression level is deregulated in human cancer. It has been also demonstrated that de-regulated levels of H19 could affect cancer biology by various mechanisms including microRNA (miRNA) production (like miR-675), miRNA sponging and epigenetic modifications. Furthermore, lncRNA could act as a potential diagnosis and prognosis biomarkers and also a candidate therapeutic approach for different human cancers. In this narrative review, we shed light on the molecular mechanism of H19 in cancer development and pathogenesis. Moreover, we discussed the expression pattern and diagnostic and therapeutic importance of H19 as a potential biomarker in a range of human malignancies from breast to osteosarcoma cancer.

Non-coding RNAs, metabolic stress and adaptive mechanisms in cancer

Metabolic reprogramming in cancer describes the multifaceted alterations in metabolism that contribute to tumorigenesis. Major determinants of metabolic phenotypes are the changes in signalling pathways associated with oncogenic activation together with cues from the tumor microenvironment. Therein, depleted oxygen and nutrient levels elicit metabolic stress, requiring cancer cells to engage adaptive mechanisms. Non-coding RNAs (ncRNAs) act as regulatory elements within metabolic pathways and their widespread dysregulation in cancer contributes to altered metabolic phenotypes. Indeed, ncRNAs are the regulatory accomplices of many prominent effectors of metabolic reprogramming including c-MYC and HIFs that are activated by metabolic stress. By example, this review illustrates the range of ncRNAs mechanisms impacting these effectors throughout their DNA-RNA-protein lifecycle along with presenting the mechanistic roles of ncRNAs in adaptive responses to glucose, glutamine and lipid deprivation. We also discuss the facultative activation of metabolic enzymes by ncRNAs, a phenomenon which may reflect a broad but currently invisible level of metabolic regulation. Finally, the translational challenges associated with ncRNA discoveries are discussed, emphasizing the gaps in knowledge together with importance of understanding the molecular basis of ncRNA regulatory mechanisms.

Novel role of ASH1L histone methyltransferase in anaplastic thyroid carcinoma

Anaplastic thyroid cancer (ATC) is one of the most aggressive human malignancies, with an average life expectancy of ∼6 months from the time of diagnosis. The genetic and epigenetic changes that underlie this malignancy are incompletely understood. We found that ASH1-like histone lysine methyltransferase (ASH1L) is overexpressed in ATC relative to the much less aggressive and more common differentiated thyroid cancer. This increased expression was due at least in part to reduced levels of microRNA-200b-3p (miR-200b-3p), which represses ASH1L expression, in ATC. Genetic knockout of ASH1L protein expression in ATC cell lines decreased cell growth both in culture and in mouse xenografts. RNA-Seq analysis of ASH1L knockout versus WT ATC cell lines revealed that ASH1L is involved in the regulation of numerous cancer-related genes and gene sets. The pro-oncogenic long noncoding RNA colon cancer-associated transcript 1 (CCAT1) was one of the most highly (approximately 68-fold) down-regulated transcripts in ASH1L knockout cells. Therefore, we investigated CCAT1 as a potential mediator of the growth-inducing activity of ASH1L. Supporting this hypothesis, CCAT1 knockdown in ATC cells decreased their growth rate, and ChIP-Seq data indicated that CCAT1 is likely a direct target of ASH1L's histone methyltransferase activity. These results indicate that ASH1L contributes to the aggressiveness of ATC and suggest that ASH1L, along with its upstream regulator miR-200b-3p and its downstream mediator CCAT1, represents a potential therapeutic target in ATC.

VIRMA-Dependent N6-Methyladenosine Modifications Regulate the Expression of Long Non-Coding RNAs CCAT1 and CCAT2 in Prostate Cancer

RNA methylation at position N6 in adenosine (m⁶A) and its associated methyltransferase complex (MTC) are involved in tumorigenesis. We aimed to explore m⁶A biological function for long non-coding RNAs (lncRNAs) in prostate cancer (PCa) and its clinical significance. m⁶A and MTC levels in PCa cells were characterized by ELISA and western blot. Putative m⁶A-regulated lncRNAs were identified and validated by lncRNA profiler qPCR array and bioinformatics analysis, followed by m⁶A/RNA co-immunoprecipitation. Impact of m⁶A depletion on RNA stability was assessed by Actinomycin D assay. The association of m⁶A-levels with PCa prognosis was examined in clinical samples. Higher m⁶A-levels and VIRMA overexpression were detected in metastatic castration-resistant PCa (mCRPC) cells (p < 0.05). VIRMA knockdown in PC-3 cells significantly decreased m⁶A-levels (p = 0.0317), attenuated malignant phenotype and suppressed the expression of oncogenic lncRNAs CCAT1 and CCAT2 (p < 0.00001). VIRMA depletion and m⁶A reduction decreased the stability and abundance of CCAT1/2 transcripts. Higher expression of VIRMA, CCAT1, and CCAT2 as a group variable was an independent predictor of poor prognosis (HR = 9.083, CI95% 1.911–43.183, p = 0.006). VIRMA is a critical factor sustaining m⁶A-levels in PCa cells. VIRMA downregulation attenuates the aggressive phenotype of PCa by overall reduction of m⁶A-levels decreasing stability and abundance of oncogenic lncRNAs.

UCA1 long non-coding RNA: An update on its roles in malignant behavior of cancers

The lncRNA urothelial carcinoma-associated 1 (UCA1) is a 1.4 kb long transcript which has been firstly recognized in human bladder cancer cell line. Subsequent studies revealed its over-expression in a wide array of human cancer cell lines and patients' samples. In addition to conferring malignant phenotype to cells, it enhances resistance to conventional anti-cancer drugs. Moreover, transcript levels of this lncRNA have been regarded as diagnostic markers in several cancer types including gastric, bladder and liver cancers. The underlying mechanism of its participation in carcinogenesis has been identified in some cancer types. Sponging tumor suppressor miRNAs, interacting with cancer-promoting signaling pathways and enhancing cell cycle progression are among these mechanisms. Although few studies have shown anti-carcinogenic properties for this lncRNA, the bulk of evidence supports its oncogenic roles. In the current study, we have reviewed the current literature on the role of UCA1 in the carcinogenic process based on the results of in vitro studies, investigations in animal models and assessment of UCA1 expression in clinical samples.

Noncoding RNAs in Extracellular Fluids as Cancer Biomarkers: The New Frontier of Liquid Biopsies

The last two decades of cancer research have been devoted in two directions: (1) understanding the mechanism of carcinogenesis for an effective treatment, and (2) improving cancer prevention and screening for early detection of the disease. This last aspect has been developed, especially for certain types of cancers, thanks also to the introduction of new concepts such as liquid biopsies and precision medicine. In this context, there is a growing interest in the application of alternative and noninvasive methodologies to search for cancer biomarkers. The new frontiers of the research lead to a search for RNA molecules circulating in body fluids. Searching for biomarkers in extracellular body fluids represents a better option for patients because they are easier to access, less painful, and potentially more economical. Moreover, the possibility for these types of samples to be taken repeatedly, allows a better monitoring of the disease progression or treatment efficacy for a better intervention and dynamic treatment of the patient, which is the fundamental basis of personalized medicine. RNA molecules, freely circulating in body fluids or packed in microvesicles, have all the characteristics of the ideal biomarkers owing to their high stability under storage and handling conditions and being able to be sampled several times for monitoring. Moreover, as demonstrated for many cancers, their plasma/serum levels mirror those in the primary tumor. There are a large variety of RNA species noncoding for proteins that could be used as cancer biomarkers in liquid biopsies. Among them, the most studied are microRNAs, but recently the attention of the researcher has been also directed towards Piwi-interacting RNAs, circular RNAs, and other small noncoding RNAs. Another class of RNA species, the long noncoding RNAs, is larger than microRNAs and represents a very versatile and promising group of molecules which, apart from their use as biomarkers, have also a possible therapeutic role. In this review, we will give an overview of the most common noncoding RNA species detectable in extracellular fluids and will provide an update concerning the situation of the research on these molecules as cancer biomarkers.

Association of lncRNA CCAT2 and CASC8 Gene Polymorphisms with Hepatocellular Carcinoma

The worldwide incidence of hepatocellular carcinoma (HCC), the major histological type of primary liver cancer, is heterogeneous due to the variable prevalence of etiological factors, indicating a correlation of HCC risk with genetic variations among individuals. Among long non-coding RNAs (lncRNAs) located in the chromosome 8q24 loci and involved in the carcinogenesis are colon cancer associated transcript 2 (CCAT2) and cancer susceptibility candidate 8 (CASC8). In this study, the association of CCAT2 and CASC8 gene polymorphisms with the occurrence of HCC was explored between 397 HCC patients and 1195 controls. We found that carriers of rs6983267 GG in CCAT2 were more susceptible to HCC, with the odds ratio (OR) and adjusted odds ratio (AOR) being 1.532 (95% CI, 1.103–2.129; p = 0.011) and 1.627 (95% CI, 1.120–2.265; p = 0.033), respectively. Moreover, for patients stratified by age (under 65), gender (male only), or status of drinking (habitual drinkers), a protective effect of CASC8 rs3843549 on presenting high Child–Pugh scores, metastatic vascular invasion, or large-size tumors was observed in a dominant model. Collectively, our data reveal association of CCAT2 and CASC8 gene polymorphisms with the occurrence and progression of HCC.

The functions and oncogenic roles of CCAT1 in human cancer

In various human cancers, long non-coding RNAs (lncRNAs), a novel class of RNAs longer than 200 nucleotides without protein-coding potential, are implicated in a variety of biological processes, such as cell proliferation, invasion, metastasis, and apoptosis through regulation of gene expression at various levels including chromatin, splicing, transcriptional and post-transcriptional levels. However, the mechanisms underlying these are still elusive. Colon cancer-associated transcript 1(CCAT1) has received increased attention among those lncRNAs. Studies have shown high expression pattern and oncogenic role of CCAT1 in different types of cancer, and aberrant expression of CCAT1 has been involved in tumor-genesis, progression, metastasis, and patient survival via regulating different target genes and signaling pathways. In this review, we first introduce the concept, identification, and biological function of CCAT1; we then describe the mechanisms by which CCAT1 regulate the cancer proliferation and progression. In the last, we discuss emerging insights into the role of CCAT1 as potential biomarker and therapeutic target for novel treatment paradigms in cancer.

Long non-coding RNAs: Diverse roles in various disorders

BACKGROUND

Long non-coding RNAs (lncRNAs) are a group of transcripts larger than 200 nucleotides that are not translated to proteins. These transcripts regulate expression of numerous genes at different levels by acting as decoys, scaffolds, and enhancers. Thus they regulate cell development, differentiation and fate.

OBJECTIVE

To find the role of lncRNAs in various diseases.

METHODS

We searched PubMed and google scholar and summarized the data regarding the role of lncRNAs in cancer and neurologic disorders.

RESULTS

Several recent studies have shown that their expressions are up-/down-regulated in malignant tissues. Consequently, they have suggested that lncRNAs can differentiate cancer samples from normal samples. Their application as biomarker is not limited to cancers. In several neurologic or psychiatric disorders researchers have found aberrant expression of lncRNAs.

CONCLUSIONS

Taken together, lncRNAs constitute a novel vast area of research to find answer to fundamental biologic questions.