Analysis of the complex interaction of CDR1as-miRNA-protein and detection of its novel role in melanoma

Rheumatoid arthritis fibroblast-like synoviocytes maintain tumor-like biological characteristics through ciRS-7-dependent regulation of miR-7

BACKGROUND

Altered phenotype of Fibroblast-like synoviocyte(FLS) is an important cause of the pathogenesis and progression of rheumatoid arthritis(RA), but the specific mechanism causing this change has not yet been fully explained. The exact mechanism by which the biological properties of FLS change in RA is still unclear. microRNAs (miRNAs) have been shown to affect changes in the biological properties of RA-FLS, but the critical miRNAs remain to be discovered. Thus, we first used miRNA microarray and WGCNA to confirm the RA-FLS miRNA landscape and establish their biological functions via network analyses at the system level, as well as to provide a platform for modulating the overall phenotypic effects of RA-FLS.

METHODS

We enrolled a total of 3 patients with RA and 3 healthy participants, constructed a network analysis of via miRNA microarray and RNA-sequencing. Furthermore, the coexpression analyses of miR-7 and ciRS-7 were verified by siRNA transfection, overexpression and qPCR analyses. Finally, we evaluated the effects of adjusting the expression levels of miR-7 and ciRS-7 on RA-FLS, respectively.

RESULTS

We identified distinct miRNA features in RA-FLS, including miR-7, which was significantly lower expressed. Furthermore, we discovered the negative regulatory relationship between ciRS-7 and miR-7 in RA-FLS. Finally, we overexpressed miR-7 in RA-FLS and discovered that miR-7 inhibited RA-FLS hyperproliferation, migration, invasion, and apoptosis, whereas ciRS-7 overexpression reversed these effects.

CONCLUSIONS

The results indicate that the dysregulation of miR-7 in FLS may be involved in the pathological processes of RA and that ciRS-7 induced the suppression of tumor-like biological characters of RA-FLS via modulation of miR-7. These findings help us understand the essential roles of a regulatory interaction between ciRS-7 and miR-7 mediating disease activity of RA, and will facilitate to develop potential intervention target for RA.

Role of Non-Coding RNA of Human Platelet in Cardiovascular Disease

Cardiovascular diseases (CVD) are the major cause of death in the world. Numerous genetic studies involving transcriptomic approaches aimed at the detailed understanding of the disease and the development of new therapeutic strategies have been conducted over recent years. There has been an increase in research on platelets, which are implicated in CVD due to their capacity to release regulatory molecules that affect various pathways. Platelets secrete over 500 various kinds of molecules to plasma including large amounts of non-coding (nc) RNA (miRNA, lncRNA or circRNA). These ncRNA correspond to 98% of transcripts that are not translated into proteins as they are important regulators in physiology and disease. Thus, miRNAs can direct protein complexes to mRNAs through base-pairing interactions, thus causing translation blockage or/and transcript degradation. The lncRNAs act via different mechanisms by binding to transcription factors. Finally, circRNAs act as regulators of miRNAs, interfering with their action. Alteration in the repertoire and/or the amount of the platelet-secreted ncRNA can trigger CVD as well as other diseases. NcRNAs can serve as effective biomarkers for the disease or as therapeutic targets due to their disease involvement. In this review, we will focus on the most important ncRNAs that are secreted by platelets (9 miRNA, 9 lncRNA and 5 circRNA), their association with CVD, and the contribution of these ncRNA to CVD risk to better understand the relation between ncRNA of human platelet and CVD.

The Prognostic and Predictive Significance of circRNA CDR1as in Tumor Progression

Cerebellar degeneration-related protein 1 antisense (CDR1as) is an important member of the circRNAs family, also known as cirs-7. Its main function in vivo is to act as a mir-7 sponge. Accumulated studies show that CDR1as is closely related to various diseases, especially cancer. Our analysis show that CDR1as expression in human cancer is significantly associated with poor overall survival (hazard ratio [HR] = 2.50, 95% confidence interval [CI] = 2.06–3.04; p < 0.00001) and that high CDR1as expression is associated with the tumor node metastasis stage (odds ratio [OR] = 2.13, 95% CI = 1.63–2.78; p < 0.00001), and distant metastasis (OR = 3.50, 95% CI = 1.90–6.64; p < 0.00001). Furthermore, the results reveal the prognostic significance of CDR1as in neoplasms of the digestive system (HR = 1.69, 95% CI = 2.14–2.71; p < 0.001), colorectal cancer (HR = 1.34, 95% CI = 1.96–2.85; p < 0.001), and non-small cell lung cancer (HR = 2.40, 95% CI = 3.42–4.83; p = 0.008). In this study, we summarize in detail the latest research findings and demonstrate the function and regulatory mechanism of CDR1as in various cancer processes, and its potential as a biomarker for cancer prevention and prognosis.

CircRNA ciRS-7: a Novel Oncogene in Multiple Cancers

circular RNA ciRS-7 (ciRS-7) is a type of endogenous circular RNA (circRNA) with a closed circular structure. Since Hansen first demonstrated that ciRS-7 could serve as a microRNA sponge in 2013, researchers have paid increased attention to this circRNA. ciRS-7 plays a crucial role in regulating RNA transcription, downstream gene expression, and protein production. Moreover, ciRS-7 acts as an oncogene and promotes tumor progression through competitively inhibiting miR-7 in various types of cancers. ciRS-7 has been identified to be closely associated with breast cancer, nasopharyngeal carcinoma, lung cancer, hepatocellular carcinoma, cervical cancer, osteosarcoma, melanoma, colorectal cancer, esophageal squamous cell carcinoma, gastric cancer, pancreatic cancer, laryngeal squamous cell carcinoma, and cholangiocarcinoma. In this review, we summarize the biological characteristics, molecular mechanisms, and future challenges of ciRS-7 in multiple tumors.

The Emerging Picture of the Roles of CircRNA-CDR1as in Cancer

Circular RNAs (circRNAs) are covalently closed circular structures without 5′ caps and 3′ tails, which are mainly formed from precursor mRNAs (pre-mRNAs) via back-splicing of exons. With the development of RNA sequencing and bioinformatic analysis, circRNAs were recently rediscovered and found to be widely expressed in the tree of life. Cerebellar degeneration-related protein 1 antisense RNA (CDR1as) is recognized as one of the most well-identified circRNAs. It contains over 70 miR-7 binding sites and can regulate gene activity by sponging miR-7. Increasing numbers of studies have recently demonstrated that CDR1as is abnormally expressed in many types of tumors, such as colorectal cancer, cholangiocarcinoma and osteosarcoma, and plays a vital role in the development of cancer. However, there are few reviews focusing on CDR1as and cancer. Hence, it is important to review and discuss the role of CDR1as in cancer. Here, we first review the main biological features of CDR1as. We then focus on the expression and roles of CDR1as in cancer. Finally, we summarize what is known on the role of CDR1as in cancer and discuss future prospects in this area of research.

Disease-Associated Circular RNAs: From Biology to Computational Identification

Circular RNAs (circRNAs) are endogenous RNAs with a covalently closed continuous loop, generated through various backsplicing events of pre-mRNA. An accumulating number of studies have shown that circRNAs are potential biomarkers for major human diseases such as cancer and Alzheimer's disease. Thus, identification and prediction of human disease-associated circRNAs are of significant importance. To this end, a computational analysis-assisted strategy is indispensable to detect, verify, and quantify circRNAs for downstream applications. In this review, we briefly introduce the biology of circRNAs, including the biogenesis, characteristics, and biological functions. In addition, we outline about 30 recent bioinformatic analysis tools that are publicly available for circRNA study. Principles for applying these computational strategies and considerations will be briefly discussed. Lastly, we give a complete survey on more than 20 key computational databases that are frequently used. To our knowledge, this is the most complete and updated summary on publicly available circRNA resources. In conclusion, this review summarizes key aspects of circRNA biology and outlines key computational strategies that will facilitate the genome-wide identification and prediction of circRNAs.

Association between Circular RNA CDR1as and Post-Infarction Cardiac Function in Pig Ischemic Heart Failure: Influence of the Anti-Fibrotic Natural Compounds Bufalin and Lycorine

Anti-fibrotic therapies are of increasing interest to combat cardiac remodeling and heart failure progression. Recently, anti-fibrotic circular RNAs (circRNAs) have been identified in human and rodent cardiac tissue. In vivo (rodent) experiments proved cardiac anti-fibrotic effects of the natural compounds bufalin and lycorine by downregulating miRNA-671-5p, associated with a theoretic increase in the tissue level of circRNA CDR1as. Accordingly, we hypothesized that both anti-fibrotic drugs may inhibit focal myocardial fibrosis of the remodeled left ventricle (LV) also in a translational large animal model of heart failure (HF). Domestic pigs were repeatedly treated with subcutaneous injections of either bufalin, lycorine, or saline, (n = 5/group) between days 7-21 post acute myocardial infarction (AMI). At the 2-month follow-up, both bufalin and lycorine led to significantly reduced cardiac fibrosis. Bufalin treatment additionally led to smaller end-diastolic volumes, higher LV ejection fraction (EF), and increased expression of CDR1as of the AMI region. Elevated tissue levels of the circRNA CDR1as in the AMI region of the pig heart correlated significantly with LV and right ventricular EF, LV stroke volume, and negatively with infarct size. In conclusion, we successfully identified the circRNA CDR1as in pig hearts and show a significant association with improved LV and RV function by anti-fibrotic therapies in a translational animal model of HF.

Biogenesis, Features, Functions, and Disease Relationships of a Specific Circular RNA: CDR1as

In 2011, Hansen discovered the natural antisense transcript (NAT) of the cerebellar degeneration-related protein 1 gene (CDR1), and further described CDR1 NAT as a circular RNA (CircRNA). CDR1 antisense RNA (CDR1as), which is the official name of CDR1 NAT, is conserved and extensively expressed in most eutherian mammal brains and other specialized tissues. Further studies have elucidated its biogenesis, features, functions, and relationships with diseases. CDR1as is involved in many disease processes as a microRNA (miR) sponge. Therefore, it seems that further research on CDR1as could facilitate the diagnosis and treatment of some diseases, such as cancer and diabetes. However, a detailed analysis of the results of studies on CDR1as revealed that they are inconsistent and make unclear conclusions. In this review, we gathered and analyzed the recent studies about CDR1as in detail and aimed to elucidate accurate conclusions from them.

circRNA CDR1as Regulated the Proliferation of Human Periodontal Ligament Stem Cells under a Lipopolysaccharide-Induced Inflammatory Condition

circRNA CDR1as (CDR1as) has been demonstrated to play important roles in a variety of inflammation-related diseases by acting as miRNA sponges. The present study is aimed at investigating the potential roles of CDR1as in the proliferation of human periodontal ligament stem cells (PDLSCs) under an inflammatory condition induced by Porphyromonas gingivalis-derived lipopolysaccharide (LPS). Human periodontal ligament cells (PDLCs) were isolated from periodontal ligament tissue, and PDLSCs were sorted from PDLCs based on the STRO-1 expression through fluorescence-activated cell sorting. We further found that CDR1as was significantly downregulated in LPS-treated PDLSCs compared to untreated cells, as well as in normal periodontal ligament tissues compared to periodontitis tissues. Knockdown of CDR1as promoted LPS-induced proliferative inhibition of PDLSCs, whereas overexpression of CDR1as alleviated the LPS-induced proliferative ability of PDLSCs. Mechanistically, CDR1as functioned as an miR-7 sponge to activate the ERK signal pathway to mediate the inhibition effect of LPS on cell proliferation. Taken together, our findings revealed the effects of the interacting pair of CDR1as/miR-7 on the proliferation ability of PDLSCs within their surrounding inflammatory microenvironment of periodontitis.

Circular RNAs: epigenetic regulators in cancerous and noncancerous skin diseases

The most frequent kind of malignancy in the universe is skin cancer, which has been categorized into non-melanoma and melanoma skin cancer. There are no complete information of the skin carcinogenesis process. A variety of external and internal agents contribute to the non-melanoma and melanoma skin cancer pathogenesis. These factors are epigenetic changes, X-rays, genetic, arsenic compounds, UV rays, and additional chemical products. It was found that there could be a relationship between the appearing novel and more suitable therapies for participants in this class of diseases and detection of basic molecular paths. A covalently closed loop structure bond connecting the 5' and 3' ends characterizes a new group of extensively expressed endogenous regulatory RNAs, which are called circular RNAs (circRNAs). Mammals commonly express circRNAs. They are of high importance in tumorigenesis. Multiple lines evidence indicated that a variety of circular RNAs are associated with initiation and development of skin-related diseases such as skin cancers. Given that different circular RNAs (hsa_circ_0025039, hsa_circRNA006612, circRNA005537, and circANRIL) via targeting various cellular and molecular targets (e.g., CDK4, DAB2IP, ZEB1, miR-889, and let-7c-3p) exert their effects on skin cancers progression. Herein, for first time, we summarized different circular RNAs in skin cancers and noncancerous diseases. Moreover, we highlighted crosstalk between circular RNAs and ceRNAs in cancerous conditions.