CSCD2: an integrated interactional database of cancer-specific circular RNAs.
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ABSTRACT:
SUBMITTER: Feng J
PROVIDER: S-EPMC8728299 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Circular RNA (circRNA) is a large group of RNA family extensively existed in cells and tissues. High-throughput sequencing provides a way to view circRNAs across different samples, especially in various diseases. However, there is still no comprehensive database for exploring the cancer-specific circRNAs. We collected 228 total RNA or polyA(-) RNA-seq samples from both cancer and normal cell lines, and identified 272 152 cancer-specific circRNAs. A total of 950 962 circRNAs were identified in normal samples only, and 170 909 circRNAs were identified in both tumor and normal samples, which could be further used as non-tumor background. We constructed a cancer-specific circRNA database (CSCD, http://gb.whu.edu.cn/CSCD). To understand the functional effects of circRNAs, we predicted the microRNA response element sites and RNA binding protein sites for each circRNA. We further predicted potential open reading frames to highlight translatable circRNAs. To understand the association between the linear splicing and the back-splicing, we also predicted the splicing events in linear transcripts of each circRNA. As the first comprehensive cancer-specific circRNA database, we believe CSCD could significantly contribute to the research for the function and regulation of cancer-associated circRNAs.
| S-EPMC5753219 | biostudies-literature
Project description:Abstract Bladder cancer (BC) is the most common urinary system malignancy and is a serious threat to human health. Circular RNAs (circRNAs) are members of a newly defined class of noncoding RNAs (ncRNAs) that can regulate gene expression at the transcriptional or posttranscriptional level. Studies have shown that circRNAs are related to the clinicopathological characteristics, prognosis, and chemosensitivity of BC, and basic research has further confirmed that changes in the expression of circRNAs in BC are closely related to various tumor biological functions. CircRNAs promote tumor development by interacting with miRNAs to regulate transcription factors and both classical and nonclassical tumor signaling pathways. The nonclassical signaling pathways are related to cell cycle progression, epithelial–mesenchymal transition (EMT), extracellular matrix maintenance, and tumor stem cell maintenance. In this article, the relationships between circRNAs and the clinical characteristics of BC are reviewed, and the molecular mechanisms by which circRNAs promote tumor development are explored.
| S-EPMC7535116 | biostudies-literature
Project description:Circular RNAs are highly stable molecules present in all eukaryotes generated by distinct transcript processing. We have exploited poly(A-) RNA-Seq data generated in our lab in MCF-7 breast cancer cells to define a compilation of exonic circRNAs more comprehensive than previously existing lists. Development of a novel computational tool, named CircHunter, allowed us to more accurately characterize circRNAs and to quantitatively evaluate their expression in publicly available RNA-Seq data from breast cancer cell lines and tumor tissues. We observed and confirmed, by ChIP analysis, that exons involved in circularization events display significantly higher levels of the histone post-transcriptional modification H3K36me3 than non-circularizing exons. This result has potential impact on circRNA biogenesis since H3K36me3 has been involved in alternative splicing mechanisms. By analyzing an Ago-HITS-CLIP dataset we also found that circularizing exons overlapped with an unexpectedly higher number of Ago binding sites than non-circularizing exons. Finally, we observed that a subset of MCF-7 circRNAs are specific to tumor versus normal tissue, while others can distinguish Luminal from other tumor subtypes, thus suggesting that circRNAs can be exploited as novel biomarkers and drug targets for breast cancer.
| S-EPMC5865691 | biostudies-other
Project description:BACKGROUND:Circular RNAs (circRNAs) play important roles in regulating gene expression through binding miRNAs and RNA binding proteins. Genetic variation of circRNAs may affect complex traits/diseases by changing their binding efficiency to target miRNAs and proteins. There is a growing demand for investigations of the functions of genetic changes using large-scale experimental evidence. However, there is no online genetic resource for circRNA genes. RESULTS:We performed extensive genetic annotation of 295,526 circRNAs integrated from circBase, circNet and circRNAdb. All pre-computed genetic variants were presented at our online resource, circVAR, with data browsing and search functionality. We explored the chromosome-based distribution of circRNAs and their associated variants. We found that, based on mapping to the 1000 Genomes and ClinVAR databases, chromosome 17 has a relatively large number of circRNAs and associated common and health-related genetic variants. Following the annotation of genome wide association studies (GWAS)-based circRNA variants, we found many non-coding variants within circRNAs, suggesting novel mechanisms for common diseases reported from GWAS studies. For cancer-based somatic variants, we found that chromosome 7 has many highly complex mutations that have been overlooked in previous research. CONCLUSION:We used the circVAR database to collect SNPs and small insertions and deletions (INDELs) in putative circRNA regions and to identify their potential phenotypic information. To provide a reusable resource for the circRNA research community, we have published all the pre-computed genetic data concerning circRNAs and associated genes together with data query and browsing functions at http://soft.bioinfo-minzhao.org/circvar .
| S-EPMC7599103 | biostudies-literature
Project description:It has been known that circular RNAs are widely expressed in human tissues and cells, and play important regulatory roles in physiological or pathological processes. However, there is lack of comprehensively annotated human circular RNAs database. In this study we established a circRNA database, named as circRNADb, containing 32,914 human exonic circRNAs carefully selected from diversified sources. The detailed information of the circRNA, including genomic information, exon splicing, genome sequence, internal ribosome entry site (IRES), open reading frame (ORF) and references were provided in circRNADb. In addition, circRNAs were found to be able to encode proteins, which have not been reported in any species. 16328 circRNAs were annotated to have ORF longer than 100 amino acids, of which 7170 have IRES elements. 46 circRNAs from 37 genes were found to have their corresponding proteins expressed according mass spectrometry. The database provides the function of data search, browse, download, submit and feedback for the user to study particular circular RNA of interest and update the database continually. circRNADb will be built to be a biological information platform for circRNA molecules and related biological functions in the future. The database can be freely available through the web server at http://reprod.njmu.edu.cn/circrnadb.
| S-EPMC5057092 | biostudies-literature
Project description:Tongue squamous cell carcinoma (TSCC) is the most frequent type of oral cancer associated with high malignancy. Circular RNAs (circRNAs) are a form of non?coding RNA with stable and conserved expression in mammalian cells. The aim of the present study was to investigate circRNAs expression profiles in TSCC, and examine the roles and potential mechanisms of circRNA?081069 (circ_081069). A high?throughput circRNA microarray analysis of tumor samples and adjacent normal tissues from four patients with TSCC was performed. Bioinformatic analysis was conducted to screen the differentially expressed circRNAs. Reverse transcription?quantitative PCR was performed to confirm the microarray results. A migration assay and proliferation assay were performed to detect the migratory and proliferative ability of TSCC cells. A luciferase assay was conducted to investigate the interaction between circ_081069 and microRNA (miRNA/miR)?665. In total, 335 circRNAs were found to be differentially expressed in tumor tissues. Among them, 59 were upregulated and 276 were downregulated (P<0.05; fold change ?2 or ?0.5). A total of seven circRNAs, including two upregulated and five downregulated circRNAs, were further confirmed using quantitative PCR analysis in the ten paired TSCC tissues and adjacent normal tissues. The present study showed that circRNA_081069 promoted the migratory and proliferative ability of TSCC cells in vitro. Furthermore, the potential circRNA?miRNA interactions were predicted, and the present results identified miR?665 as a miRNA target of circ_081069. The present results suggested that circRNAs may be involved in TSCC development, and understanding the interaction between circ_081069 and miR?665 may facilitate the development of novel diagnostic and therapeutic targets for TSCC.
| S-EPMC7057816 | biostudies-literature
Project description:CircRNAs are a class of RNA molecules that structurally form closed loops. CircRNAs are abundant in eukaryotic transcripts and show certain levels of tissue and cell specificity. CircRNAs have been suggested to regulate gene expression at transcriptional, post-transcriptional, and translational levels. An increasing number of studies have shown that circRNAs play important roles in the development and progression of diseases including cancer. In particular, circRNAs have shown great potential in cancer diagnosis, prognosis, and therapy. In this review, we provide an overview of the biogenesis and characteristics of circRNAs, succinctly describe their functions, and comprehensively discuss about the recent advances in the roles of circRNAs in cancer with an emphasis on their clinical values.
| S-EPMC5667461 | biostudies-literature
Project description:TransCirc (https://www.biosino.org/transcirc/) is a specialized database that provide comprehensive evidences supporting the translation potential of circular RNAs (circRNAs). This database was generated by integrating various direct and indirect evidences to predict coding potential of each human circRNA and the putative translation products. Seven types of evidences for circRNA translation were included: (i) ribosome/polysome binding evidences supporting the occupancy of ribosomes onto circRNAs; (ii) experimentally mapped translation initiation sites on circRNAs; (iii) internal ribosome entry site on circRNAs; (iv) published N-6-methyladenosine modification data in circRNA that promote translation initiation; (v) lengths of the circRNA specific open reading frames; (vi) sequence composition scores from a machine learning prediction of all potential open reading frames; (vii) mass spectrometry data that directly support the circRNA encoded peptides across back-splice junctions. TransCirc provides a user-friendly searching/browsing interface and independent lines of evidences to predicte how likely a circRNA can be translated. In addition, several flexible tools have been developed to aid retrieval and analysis of the data. TransCirc can serve as an important resource for investigating the translation capacity of circRNAs and the potential circRNA-encoded peptides, and can be expanded to include new evidences or additional species in the future.
| S-EPMC7778967 | biostudies-literature
Project description:Circular RNAs (circRNAs) are implicated in a variety of cancers. However, the roles of circRNAs in gastric cancer (GC) remain largely unknown. In the current study, circRNAs expression profiles were screened in GC, using 5 pairs of GC and matched non-GC tissues with circRNA chip. Preliminary results were verified with quantitative PCR (qRT-PCR). Briefly, total of 713 circRNAs were differentially expressed in GC tissues vs. non-GC tissues (fold change ≥ 2.0, p < 0.05): 191 were upregulated, whereas 522 were downregulated in GC tissues. qRT-PCR analysis of randomly selected 7 circRNAs from the 713 circRNAs in 50 paired of GC vs. non-GC control tissues confirmed the microarray data. Gene ontology (GO) and KEGG pathway analyses showed that many circRNAs are implicated in carcinogenesis. Among differentially expressed circRNAs, hsa_circ_0076304, hsa_circ_0035431, and hsa_circ_0076305 had the highest magnitude of change. These results provided a preliminary landscape of circRNAs expression profile in GC.
| S-EPMC5567231 | biostudies-literature
Project description:Gastric cancer (GC) is the third most common cause of cancer-related death worldwide. Advanced diagnosis and high rates of relapse and metastasis are associated with the poor prognosis of this disease. GC has a complex etiopathogenesis of which the underlying mechanisms remain to be explored. Studies on circular RNAs (circRNAs), noncoding RNAs that may be potential targets in GC, have made substantial progress over the past few years. CircRNAs exert important effects on the onset and progression of GC. Hence, this article aims to summarize the findings of recent studies of circRNAs related to GC and to describe the underlying mechanisms and potential applications. The findings indicate that circRNAs participate in GC regulation, proliferation, invasion, and metastasis through regulating microRNAs, proteins, genes, and signaling pathways. In addition, dysregulated circRNAs may be used as novel diagnostic and prognostic biomarkers or therapeutic targets. This review is expected to facilitate a better understanding of GC, and it suggests novel circRNA-based methods to inhibit or prevent GC.
| S-EPMC6916696 | biostudies-literature