Circular RNAS: novel biomarkers of disease activity in systemic lupus erythematosus?

Integrating clinical data mining, network analysis and experimental validation reveal the anti-inflammatory mechanism of Huangqin Qingre Chubi Capsule in rheumatoid arthritis treatment

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqin Qingre Chubi Capsule (HQC) is a Chinese medicinal compound used for the treatment of damp-heat pattern rheumatism, guided by the traditional Chinese medicine syndrome differentiation practice. HQC has been used in the clinical treatment of rheumatic diseases for more than 20 years with remarkable efficacy. HQC has been experimentally shown to exert anti-arthritic effects via the Wnt signaling pathway.

AIM OF THE STUDY

This study used clinical data mining, network analysis, and in vitro and in vivo tests to investigate the anti-arthritic and possible anti-inflammatory mechanism of HQC. Specifically, emphasis was placed on the function of the hsa_circ_0091,685/EIF4A3/IL-17 axis in the anti-inflammatory process.

MATERIALS AND METHODS

A random walk model was used to evaluate the effects of HQC on clinical immune inflammatory marker function in patients with RA. Network analysis was used to predict the potential target genes and pathways of HQC. Hematoxylin & eosin, safranin O-fast green and toluidine blue staining, immunohistochemistry, and transmission electron microscopy were performed to evaluate the anti-arthritic effects of HQC in rat models. Cell Counting Kit-8 assay, quantitative real-time polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay, and RNA pull-down were used to study the anti-proliferation and anti-inflammatory mechanisms of HQC.

RESULTS

Patients with RA who underwent HQC treatment showed a significant reduction in inflammatory response levels, according to retrospective clinical study. Network analysis revealed that HQC potentially targeted genes and pathways related to inflammation, especially IL-6, IL-17, TNF-α, IL-23, and IL-17 signaling pathway. Animal experiments showed that HQC inhibits inflammation through the IL-17 signaling pathway in rat models. Cellular experiments showed that HQC-containing serum inhibited the inflammatory response in patients with RA-FLS or RA by blocking hsa_circ_0091,685 and EIF4A3 expression.

CONCLUSION

In RA patients, HQC reduces the inflammatory response. The antiproliferative and anti-inflammatory qualities of HQC are responsible for its therapeutic impact. The suppression of the hsa_circ_0091,685/EIF4A3/IL-17 axis was linked to these favorable outcomes.

Systemic lupus erythematosus: From non-coding RNAs to exosomal non-coding RNAs

Systemic lupus erythematosus (SLE), as an immunological illness, frequently impacts young females. Both vulnerabilities to SLE and the course of the illness's clinical symptoms have been demonstrated to be affected by individual differences in non-coding RNA expression. Many non-coding RNAs (ncRNAs) are out of whack in patients with SLE. Because of the dysregulation of several ncRNAs in peripheral blood of patients suffering from SLE, these ncRNAs to be showed valuable as biomarkers for medication response, diagnosis, and activity. NcRNAs have also been demonstrated to influence immune cell activity and apoptosis. Altogether, these facts highlight the need of investigating the roles of both families of ncRNAs in the progress of SLE. Being aware of the significance of these transcripts perhaps elucidates the molecular pathogenesis of SLE and could open up promising avenues to create tailored treatments during this condition. In this review we summarized various non-coding RNAs and Exosomal non-coding RNAs in SLE.

Plasma Exosomal Non-Coding RNA Profile Associated with Renal Damage Reveals Potential Therapeutic Targets in Lupus Nephritis

Despite considerable progress in our understanding of systemic lupus erythematosus (SLE) pathophysiology, patient diagnosis is often deficient and late, and this has an impact on disease progression. The aim of this study was to analyze non-coding RNA (ncRNA) packaged into exosomes by next-generation sequencing to assess the molecular profile associated with renal damage, one of the most serious complications of SLE, to identify new potential targets to improve disease diagnosis and management using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The plasma exosomes had a specific ncRNA profile associated with lupus nephritis (LN). The three ncRNA types with the highest number of differentially expressed transcripts were microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and piwi-interacting RNAs (piRNAs). We identified an exosomal 29-ncRNA molecular signature, of which 15 were associated only with LN presence; piRNAs were the most representative, followed by lncRNAs and miRNAs. The transcriptional regulatory network showed a significant role for four lncRNAs (LINC01015, LINC01986, AC087257.1 and AC022596.1) and two miRNAs (miR-16-5p and miR-101-3p) in network organization, targeting critical pathways implicated in inflammation, fibrosis, epithelial-mesenchymal transition and actin cytoskeleton. From these, a handful of potential targets, such as transforming growth factor-β (TGF-β) superfamily binding proteins (activin-A, TGFB receptors, etc.), WNT/β-catenin and fibroblast growth factors (FGFs) have been identified for use as therapeutic targets of renal damage in SLE.

The emerging role of noncoding RNAs in systemic lupus erythematosus: new insights into the master regulators of disease pathogenesis

Auto-immune diseases are a form of chronic disorders in which the immune system destroys the body's cells due to a loss of tolerance to self-antigens. Systemic lupus erythematosus (SLE), identified by the production of autoantibodies in different body parts, is one of the most well-known examples of these diseases. Although the etiology of SLE is unclear, the disease's progression may be affected by genetic and environmental factors. As studies in twins provide adequate evidence for genetic involvement in the SLE, other phenomena such as metallization, histone modifications, and alterations in the expression of noncoding RNAs (ncRNAs) also indicate the involvement of epigenetic factors in this disease. Among all the epigenetic alterations, ncRNAs appear to have the most crucial contribution to the pathogenesis of SLE. The ncRNAs' length and size are divided into three main classes: micro RNAs, long noncoding RNAs (LncRNA), and circular RNAs (circRNAs). Accumulating evidence suggests that dysregulations in these ncRNAs contributed to the pathogenesis of SLE. Hence, clarifying the function of these groups of ncRNAs in the pathophysiology of SLE provides a deeper understanding of the disease. It also opens up new opportunities to develop targeted therapies for this disease.

Circular RNA circLOC101928570 suppresses systemic lupus erythematosus progression by targeting the miR-150-5p/c-myb axis

Background

Accumulating evidence supports the implication of circular RNAs (circRNAs) in systemic lupus erythematosus (SLE). However, little is known about the detailed mechanisms and roles of circRNAs in the pathogenesis of SLE.

Methods

Quantitative real-time PCR was used to determine the levels of circLOC101928570 and miR-150-5p in peripheral blood mononuclear cells of SLE. Overexpression and knockdown experiments were conducted to assess the effects of circLOC101928570. Fluorescence in situ hybridization, RNA immunoprecipitation, luciferase reporter assays, Western blot, flow cytometry analysis and enzyme-linked immunosorbent assay were used to investigate the molecular mechanisms underlying the function of circLOC101928570.

Results

The results showed that the level of circLOC101928570 was significantly downregulated in SLE and correlated with the systemic lupus erythematosus disease activity index. Functionally, circLOC101928570 acted as a miR-150-5p sponge to relieve the repressive effect on its target c-myb, which modulates the activation of immune inflammatory responses. CircLOC101928570 knockdown enhanced apoptosis. Moreover, circLOC101928570 promoted the transcriptional level of IL2RA by directly regulating the miR-150-5p/c-myb axis.

Conclusion

Overall, our findings demonstrated that circLOC101928570 played a critical role in SLE. The downregulation of circLOC101928570 suppressed SLE progression through the miR-150-5p/c-myb/IL2RA axis. Our findings identified that circLOC101928570 serves as a potential biomarker for the diagnosis and therapy of SLE.

Hsa_circ_0008301 as a potential biomarker of disease activity for primary Sjogren's syndrome: Increased expression in peripheral blood of patients with primary Sjogren's syndrome

OBJECTIVES

To explore the expression level, association with disease activity and clinical significance of hsa_circ_0008301 in the peripheral blood of patients with primary Sjögren's syndrome (pSS).

METHODS

We selected 70 pSS patients hospitalized under the Rheumatology service line at the General Hospital of Ningxia Medical University from September 2018 to June 2021 as the disease group, in which general data and clinical indicators were collected. Fifty-three patients with healthy physical examinations for the same period were selected as the healthy control group, and 32 patients with non-pSS rheumatic diseases were selected as the disease control group. We collected peripheral blood samples and used fluorescence quantitative PCR to detect the expression level of hsa_circ_0008301. In addition, we analyzed the association of the expression level of hsa_circ_0008301 with the clinical characteristics and disease activity of pSS patients. A receiver operating characteristic curve was used to evaluate the diagnosis and the disease activity value of hsa_circ_0008301 in patients with pSS. Meanwhile, we analyzed the differential expression of hsa_circ_0008301 in 24 pSS patients selected from the disease group before and after treatment.

RESULTS

The relative expression of hsa_circ_0008301 in the peripheral blood of pSS patients was significantly higher than that in the control groups including healthy control group and disease control group. The expression level of hsa_circ_0008301 was high in pSS patients with a course of disease ≥ 10 years, fatigue symptoms, platelets < 100*10^9/L, erythrocyte sedimentation rate ≥ 50 mm/h, immunoglobulin IgG > 16 g/L, complement C3 < 0.9 g/L, ESSDAI score ≥ 5 and positively correlated with the above groups. Furthermore, ROC analysis showed that hsa_circ_0008301 was statistically significant between pSS patients and healthy controls. We selected patients from the disease group before and after treatment and showed that the expression level of hsa_circ_0008301 decreased significantly after treatment, compared with before. The area under the curve (AUC) was 0.825 (95% CI: 0.754 ∼ 0.897; P < 0.0001). The AUC of hsa_circ_0008301 in pSS patients and the disease control group was 0.673 (95% CI: 0.563 ∼ 0.782; P = 0.005), the sensitivity was 40.00%, the specificity was 93.70%, the optimal truncation value was > 0.0420, and the maximum Youden index was 0.337. In addition, ROC analysis revealed that hsa_circ_0008301 was statistically significant between disease-active patients and stable patients. The AUC value was 0.681 (95% CI: 0.553 ∼ 0.809; P = 0.010), the sensitivity was 65.90%, the specificity was 72.40%, the optimal truncation value was > 0.0285, and the maximum Youden index was 0.383. ROC analysis indicated that hsa_circ_0008301 has some value in the diagnosis and disease activity of patients with pSS. Comparison of 24 pSS patients selected from the disease group before and after treatment showed that the expression level of hsa_circ_0008301 decreased significantly after treatment compared with before treatment (Z =  - 4.257, P < 0.0001). ROC analysis indicated that hsa_circ_0008301 has some value in the diagnosis and disease activity of patients with pSS.

CONCLUSIONS

Hsa_circ_0008301 is expressed in higher levels in the peripheral blood of patients with pSS, which is related to the disease activity. It may be involved in the occurrence and development of pSS and may have a potential biomarker for the disease.

Mesenchymal Stem Cell-Derived Secretome: A Potential Therapeutic Option for Autoimmune and Immune-Mediated Inflammatory Diseases

Immune-mediated inflammatory diseases (IMIDs) encompass several entities such as "classic" autoimmune disorders or immune-mediated diseases with autoinflammatory characteristics. Adult stem cells including mesenchymal stem cells (MSCs) are by far the most commonly used type in clinical practice. However, due to the possible side effects of MSC-based treatments, there is an increase in interest in the MSC-secretome (containing large extracellular vesicles, microvesicles, and exosomes) as an alternative therapeutic option in IMIDs. A wide spectrum of MSC-secretome-related biological activities has been proven thus far including anti-inflammatory, anti-apoptotic, and immunomodulatory properties. In comparison with MSCs, the secretome is less immunogenic but exerts similar biological actions, so it can be considered as an ideal cell-free therapeutic alternative. Additionally, since the composition of the MSC-secretome can be engineered, for a future perspective, it could also be viewed as part of a potential delivery system within nanomedicine, allowing us to specifically target dysfunctional cells or tissues. Although many encouraging results from pre-clinical studies have recently been obtained that strongly support the application of the MSC-secretome in IMIDs, human studies with MSC-secretome administration are still in their infancy. This article reviews the immunomodulatory effects of the MSC-secretome in IMIDs and provides insight into the interpretation of its beneficial biological actions.

Extracellular Vesicles-ceRNAs as Ovarian Cancer Biomarkers: Looking into circRNA-miRNA-mRNA Code

Simple Summary

Patients with ovarian cancer have a very poor chance of long-term survival, usually due to advanced disease at the time of diagnosis. Emerging evidence suggests that extracellular vesicles contain noncoding RNAs such as microRNAs, piwiRNAs, circular RNAs, and long noncoding RNAs, with regulatory effects on ovarian cancer. In this review, we focus on ovarian cancer-associated circular RNA shuttled by extracellular vesicles as mediators of cancer progression and novel biomarkers in liquid biopsy. We propose a circular-RNA–microRNA-mRNA code that can reveal the regulatory network created by extracellular vesicles, noncoding RNAs, and mRNAs in ovarian cancer. Future research in this field will help to identify novel diagnostic biomarkers and druggable therapeutic targets, which will ultimately benefit patients.

Abstract

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies in females worldwide. OC is frequently diagnosed at an advanced stage due to a lack of specific symptoms and effective screening tests, resulting in a poor prognosis for patients. Age, genetic alterations, and family history are the major risk factors for OC pathogenesis. Understanding the molecular mechanisms underlying OC progression, identifying new biomarkers for early detection, and discovering potential targets for new drugs are urgent needs. Liquid biopsy (LB), used for cancer detection and management, consists of a minimally invasive approach and practical alternative source to investigate tumor alterations by testing extracellular vesicles (EVs), circulating tumor cells, tumor-educated platelets, and cell-free nucleic acids. EVs are nanosize vesicles shuttling proteins, lipids, and nucleic acids, such as DNA, RNA, and non-coding RNAs (ncRNAs), that can induce phenotypic reprogramming of target cells. EVs are natural intercellular shuttles for ncRNAs, such as microRNAs (miRNAs) and circular-RNAs (circRNAs), known to have regulatory effects in OC. Here we focus on the involvement of circRNAs and miRNAs in OC cancer progression. The circRNA-microRNA-mRNA axis has been investigated with Circbank and miRwalk analysis, unraveling the intricate and detailed regulatory network created by EVs, ncRNAs, and mRNAs in OC.

Expression profile of circRNA in peripheral blood mononuclear cells of patients with rheumatoid arthritis

Background

Circular RNAs (circRNAs) is a newly discovered non-coding RNA that can be used as biomarkers in clinical blood samples. This study aims to screen differentially expressed circular RNAs in PBMCs of patients with rheumatoid arthritis (RA) to determine new biomarkers for the diagnosis of RA.

Methods

The differentially expressed circRNAs in peripheral blood mononuclear cells (PBMCs) of 4 RA patients and 4 healthy participants were screened and analyzed by gene microarray technology. We then validated some of the differentially expressed circRNAs in PBMCs of 20 RA patients, 10 systemic lupus erythematosus (SLE) patients and 20 healthy participants using reverse transcription-quantitative polymerase chain reaction amplification (RT-qPCR). Spearman correlation test was performed to analyze the correlation between differentially expressed circRNAs and clinical variables in RA patients. Receiver operating characteristic (ROC) curves were calculated to evaluate the diagnostic value of circRNAs.

Results

Differential analysis obtained 149 circRNAs with significant up-regulated expression and 250 circRNAs with significant down-regulated expression, which predicted the miRNA targets and binding sites. Compared with SLE and health control group, hsa_circ_101328 was found to be a common gene with differential expression of RA. Besides, correlation analysis revealed significant correlation between hsa_circ_101328 and positive CRP. ROC curve analysis showed that hsa_circ_101328 has the potential of RA diagnosis.

Conclusion

We identified some dysregulated circRNAs in PBMCs from RA patients, and hsa_circ_101328 may be a novel and effective biomarker for early diagnosis of RA.

Mesenchymal Stem Cell-Derived Extracellular Vesicles as Non-Coding RNA Therapeutic Vehicles in Autoimmune Diseases

Autoimmune diseases (ADs) are characterized by the activation of the immune system against self-antigens. More common in women than in men and with an early onset, their incidence is increasing worldwide, and this, combined with their chronic nature, is contributing to an enlarged medical and economic burden. Conventional immunosuppressive agents are designed to alleviate symptoms but do not constitute an effective therapy, highlighting a need to develop new alternatives. In this regard, mesenchymal stem cells (MSCs) have demonstrated powerful immunosuppressive and regenerative effects. MSC-derived extracellular vesicles (MSC-EVs) have shown some advantages, such as less immunogenicity, and are proposed as novel therapies for ADs. In this review, we summarize current perspectives on therapeutic options for ADs based on MSCs and MSC-EVs, focusing particularly on their mechanism of action exerted through their non-coding RNA (ncRNA) cargo. A complete state-of-the-art review was performed, centralized on some of the most severe ADs (rheumatoid arthritis, autoimmune type 1 diabetes mellitus, and systemic lupus erythematosus), giving evidence that a promising field is evolving to overcome the current knowledge and provide new therapeutic possibilities centered on MSC-EVs and their role as ncRNA delivery vehicles for AD gene therapy.

Circ_0000518 promotes macrophage/microglia M1 polarization via the FUS/CaMKKβ/AMPK pathway to aggravate multiple sclerosis

Evidence has shown that circ_0000518 is upregulated in peripheral of multiple sclerosis (MS) patients, suggesting that it may play an important role in the progression of MS. However, its specific mechanism in MS progression is unclear. In this study, the human microglial clone 3 (HMC3) cells were treated with 100 ng/mL of LPS for 24 h, then the short hairpin RNA against hsa_circ_0000518 (sh-hsa_circ_0000518) was transfected into cells and incubated for 48 h. We found increased circ_0000518 expressions, increased apoptosis and oxidative stress, increased M1 phenotype marker expression, and decreased M2 phenotype marker expression in cells, and that interfering with circ_0000518 expression reversed the effect of LPS on HMC3 cells. Online bioinformatics database analysis indicated that FUS is an RNA binding protein of circ_0000518. Next, we observed increased FUS expression in LPS treated HMC3 cells, and interfering with FUS expression reduced LPS triggered apoptosis and oxidative stress, decreased M1 phenotype marker expression, and promoted M2 phenotype marker expression. Mechanistic studies revealed that interfering with FUS promoted the polarization of HMC3 cells from the M1 phenotype to the M2 phenotype via activation of CaMKKβ/AMPK-PGC-1α pathway, whereas this promoting effect was counteracted by STO-609. In an experimental autoimmune encephalomyelitis (EAE) mouse model, we observed that circ_0000518 knockdown reduced circ_0000518 and FUS expression in brain and spinal cord tissues, reduced neurological scores in mice, and alleviated inflammatory cell infiltration in the CNS. Summarily, our study identified that circ_0000518 promotes macrophage/microglial M1 polarization through the FUS/CaMKKβ/AMPK pathway and aggravates MS.

Emerging roles of circular RNAs in systemic lupus erythematosus

Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently closed single-stranded structures lacking 5'-3' polarity and a polyadenine tail. Over recent years, a growing body of studies have been conducted to explore the roles of circRNAs in human diseases. Systemic lupus erythematosus (SLE) is a severe autoimmune disorder characterized by the presence of autoantibodies and excessive inflammation, which impact multiple organs. Recent advances have begun to shed light on the roles of circRNAs in SLE, providing fresh insights into the pathogenesis of SLE and the latent capacity for translation into clinical applications. Here, we briefly introduce these "star molecules" and summarize their roles in SLE. In addition, we outline the limitations of the current studies and raise prospects for future research.

Insights Into the Involvement of Circular RNAs in Autoimmune Diseases

Circular RNAs (circRNAs) are single-stranded, endogenous, non-coding RNA (ncRNA) molecules formed by the backsplicing of messenger RNA (mRNA) precursors and have covalently closed circular structures without 5′-end caps and 3′-end polyadenylation [poly(A)] tails. CircRNAs are characterized by abundant species, stable structures, conserved sequences, cell- or tissue-specific expression, and widespread and stable presence in many organisms. Therefore, circRNAs can be used as biomarkers for the prediction, diagnosis, and treatment of a variety of diseases. Autoimmune diseases (AIDs) are caused by defects in immune tolerance or abnormal immune regulation, which leads to damage to host organs. Due to the complexity of the pathophysiological processes of AIDs, clinical therapeutics have been suboptimal. The emergence of circRNAs sheds new light on the treatment of AIDs. In particular, circRNAs mainly participate in the occurrence and development of AIDs by sponging targets. This review systematically explains the formation, function, mechanism, and characteristics of circRNAs in the context of AIDs. With a deeper understanding of the pathophysiological functions of circRNAs in the pathogenesis of AIDs, circRNAs may become reasonable, accurate, and effective biomarkers for the diagnosis and treatment of AIDs in the future.

Aberrant Non-Coding RNA Expression in Patients with Systemic Lupus Erythematosus: Consequences for Immune Dysfunctions and Tissue Damage

Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease with heterogeneous clinical manifestations. A diverse innate and adaptive immune dysregulation is involved in the immunopathogenesis of SLE. The dysregulation of immune-related cells may derive from the intricate interactions among genetic, epigenetic, environmental, and immunological factors. Of these contributing factors, non-coding RNAs (ncRNAs), including microRNAs (miRNAs, miRs), and long non-coding RNAs (lncRNAs) play critical roles in the post-transcriptional mRNA expression of cytokines, chemokines, and growth factors, which are essential for immune modulation. In the present review, we emphasize the roles of ncRNA expression in the immune-related cells and cell-free plasma, urine, and tissues contributing to the immunopathogenesis and tissue damage in SLE. In addition, the circular RNAs (circRNA) and their post-translational regulation of protein synthesis in SLE are also briefly described. We wish these critical reviews would be useful in the search for biomarkers/biosignatures and novel therapeutic strategies for SLE patients in the future.

CircRNA_09505 aggravates inflammation and joint damage in collagen-induced arthritis mice via miR-6089/AKT1/NF-κB axis

A number of circular RNAs (circRNAs) have been implicated in rheumatoid arthritis (RA) pathogenesis; however, little is known about their function and hidden molecular mechanism in immune and inflammation regulation. We investigated the role and the underlying mechanism of circRNA_09505 in RA in this study. Real-time PCR and fluorescence in situ hybridization (FISH) are adopted to estimate the quantitative expression and localization of circRNA_09505 in macrophages. The altering effect of circRNA_09505 on inflammation is investigated in vitro and in vivo by use of macrophage cell models and collagen-induced arthritis (CIA) mice. Luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) are used to confirm the circRNA_09505/miR-6089 ceRNA network predicted by bioinformatics analysis. Compared with controls, the expression of circRNA_09505 is upregulated in peripheral blood mononuclear cells (PBMCs) from patients with RA. The proliferation and cell cycle are significantly promoted when circRNA_09505 is upregulated in macrophages, whereas knockdown of circRNA_09505 inhibits macrophage proliferation and cell- cycle progression. Besides, circRNA_09505 can act as a miRNA sponge for miR-6089 in macrophages, and promote the production of TNF-α, IL-6, and IL-12 through ceRNA mechanism. Moreover, AKT1 is a direct target of miR-6089. CircRNA_09505 can promote AKT1 expression by acting as a miR-6089 sponge via IκBα/NF-κB signaling pathway in macrophages. Most interestingly, knockdown of circRNA_09505 significantly alleviates arthritis and inflammation in vivo in CIA mice. These data support the hypothesis that circRNA_09505 can function as a miR-6089 sponge and regulate inflammation via miR-6089/AKT1/NF-κB axis in CIA mice.

Circular RNA DGKB Promotes the Progression of Neuroblastoma by Targeting miR-873/GLI1 Axis

Accumulated evidences suggested that circular RNAs (circRNA) played critical roles in tumorigenesis and progression. To our knowledge, no study reported the function of circular RNA DGKB (circDGKB, circRNA ID: hsa_circ_0133622) on progression of neuroblastoma (NB). Here, we showed that circDGKB was upregulated in NB tissues compared to the normal dorsal root ganglia. Moreover, the expression level of circDGKB was negatively correlated with the survival rate of NB patients. Mechanically, overexpression of circDGKB promoted the proliferation, migration, invasion, and tumorigenesis of NB cells and reduced cell apoptosis, and vice versa. In addition, qRT-PCR and/or Western blot results showed that circDGKB overexpression inhibited the expression level of miR-873 and enhanced GLI1 expression. Moreover, miR-873 functioned an opposite role to circDGKB and significantly weakened circDGKB role in promoting NB progression. Furthermore, GLI1 upregulation also rescued the miR-873 role in inhibiting NB progression. In conclusion, our work proved that circDGKB promoted NB progression via targeting miR-873/GLI1 axis in vitro and in vivo. Our study provided a new target for NB treatment and indicated that circDGKB could act as a novel diagnostic marker for NB.

Circular RNA in renal diseases

Circular RNA (circRNA) is a newly described type of non-coding RNA. Active research is greatly enriching the current understanding of the expression and role of circRNA, and a large amount of evidence has implicated circRNA in the pathogenesis of certain renal diseases, such as renal cell carcinoma, acute kidney injury, diabetic nephropathy and lupus nephritis. Studies have found evidence that circRNAs regulate programmed cell death, invasion, and metastasis and serve as biomarkers in renal diseases. Recently, circRNAs were identified in exosomes secreted by the kidneys. Nevertheless, the function of circRNA in renal diseases remains ambiguous. Given that circRNAs are regulators of gene expression, they may be involved in the pathology of multiple renal diseases. Additionally, emerging evidence is showing that circulating circRNAs may serve as novel biomarkers for renal disease. In this review, we have summarized the identification, biogenesis, degradation, and functions of circRNA and have evaluated the roles of circRNA in renal diseases.

RNA-seq reveals the circular RNA and miRNA expression profile of peripheral blood mononuclear cells in patients with rheumatoid arthritis

OBJECTIVE

Circular RNAs (circRNAs) are a significant class of molecules involved in a wide range of diverse biological functions that are abnormally expressed in many types of diseases. The present study aimed to determine the circRNAs specifically expressed in peripheral blood mononuclear cells (PBMCs) from rheumatoid arthritis (RA) patients to identify their possible molecular mechanisms.

METHODS

To identify the circRNAs specifically expressed in RA, we started by sequencing the of PBMCs circRNA and microRNAs (miRNAs) from a RA group (n = 3) and a control group (n = 3). We constructed a network of differentially expressed circRNAs and miRNAs. Then, we selected differentially expressed circRNAs in PBMCs from 10 RA patients relative to 10 age- and sex-matched controls using real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Spearman's correlation test was used to evaluate the correlation of circRNAs with biochemical measurements.

RESULTS

A total of 165 circRNAs and 63 miRNAs were differently expressed between RA patients and healthy people according to RNA-seq, including 109 circRNAs that were significantly up-regulated and 56 circRNAs that were down-regulated among the RA patients. RT-qPCR validation demonstrated that the expression levels of hsa_circ_0001200, hsa_circ_0001566, hsa_circ_0003972, and hsa_circ_0008360 were consistent with the results from the sequencing analysis. Then, we found that there were significant correlations between the circRNAs and disease severity.

CONCLUSION

Generally, these results suggest that expression of hsa_circ_0001200, hsa_circ_0001566, hsa_circ_0003972, and hsa_circ_0008360 in PBMCs from RA patients may serve as potential biomarkers for the diagnosis of RA, and these circRNAs may influence the occurrence and development of RA.

Circular RNAs and their emerging roles as diagnostic and prognostic biomarkers in ovarian cancer

Ovarian cancer (OC), one of the gynecologic malignancies with high invasive and metastatic potential, has a low survival rate in females. Although cytoreductive surgery combined with chemotherapy is the principal treatment for OC, the prognosis remains poor, and the recurrence rate of OC remains high. It is urgent to explore novel biomarkers for the diagnosis and prognosis of OC, as well as therapeutic targets. Circular RNAs (circRNAs) are a class of highly conserved, stable and abundant noncoding RNAs (ncRNAs). Recent studies have shown that circRNAs participate in OC progression by regulating various processes, including cell proliferation, migration, invasion and apoptosis. In addition, circRNAs are potential biomarkers for OC diagnosis and prognosis. This review provides an overview of recent findings on circRNAs in OC, including their functions and molecular mechanisms, and discusses their potential roles as diagnostic and prognostic biomarkers, as well as therapeutic targets for OC.

Do lncRNAs and circRNAs expression profiles influence discoid lupus erythematosus progression?-a comprehensive analysis

Background

Long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs)are involved in the progression of discoid lupus erythematosus (DLE), but an understanding of their underlying mechanisms remains elusive. To explore the expression profiles of lncRNAs and circRNAs in DLE, we surveyed the lncRNA/circRNA and mRNA expression profiles in the epithelia of oral DLE and adjacent normal tissues.

Methods

The lesional and non-lesional lower lips of three DLE patients were analysed by RNA-sequencing (RNA-seq). The principal functions of the significantly deregulated genes were identified using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. And the correlated expression networks (coding-noncoding co-expression and lncRNAs-transcription factor-mRNA) were evaluated as well.

Results

Hundreds of significantly changed lncRNAs and mRNAs and dozens of significantly changed circRNAs were identified. lncRNA lnc-MIPOL1-6 and IncRNA IncDDX47-3 expressions were correlated with immune response-related genes, including IL19, CXCL1, CXCL11, and TNFSF15. Up-regulated IncRNA-TF network consists of 8 TFs and 74 related lncRNAs. The lncRNA-TF-gene trans-regulation consisting of 204 lncRNAs,39 TFs, and correlated 3 genes.

Conclusions

These results demonstrate that lncRNAs and circRNAs can influence the progression of DLE. Certain mRNAs/lncRNAs/circRNAs may have substantial value in DLE diagnosis and therapy.