Exosomal hsa_circ_0008925 from Urine Is Related to Chronic Renal Fibrosis.

At present, there is no noninvasive biomarker of renal fibrosis. The potential diagnostic value of urinary exosome-derived circRNAs from glomerular disease patients for renal fibrosis is still uncertain. Here, we first detected the expression of hsa_circ_0008925 in TGF-ß1-cultured HK-2 cell-derived exosomes. Secondly, we collected urine samples from 95 biopsy-proven glomerular disease patients and 34 healthy controls. The expression of hsa_circ_0008925 was analyzed, and the correlation with renal function and pathological changes was calculated. The receiver operating characteristic (ROC) curve for the diagnosis of renal fibrosis was performed. The results showed that in exosomes derived from TGF-ß1-cultured HK-2 cells, the expression of hsa_circ_0008925 was increased compared with normal cultured. Further, the expression level of hsa_circ_0008925 was increased in urinary exosomes from renal fibrosis patients and correlated with serum creatinine, blood urea nitrogen (BUN), estimated glomerular filtration rate, and cystatin C. The level of hsa_circ_0008925 was furthermore correlated with the score of tubulointerstitial fibrosis (TIF) and the score of glomerular sclerosis. The ROC curve showed that hsa_circ_0008925 can diagnose renal fibrosis at a cut-off value of 0.093 with a sensitivity of 52.2% and specificity of 96.4%. In summary, we indicated that urinary exosomal hsa_circ_0008925 could be acted as a noninvasive biomarker for renal fibrosis in glomerular diseases patients.

Extracellular circular RNA profiles in plasma and urine of healthy, male college athletes.

Circular RNA (circRNA) are a recently discovered class of RNA characterized by a covalently-bonded back-splice junction. As circRNAs are inherently more stable than other RNA species, they may be detected extracellularly in peripheral biofluids and provide novel biomarkers. While circRNA have been identified previously in peripheral biofluids, there are few datasets for circRNA junctions from healthy controls. We collected 134 plasma and 114 urine samples from 54 healthy, male college athlete volunteers, and used RNASeq to determine circRNA content. The intersection of six bioinformatic tools identified 965 high-confidence, characteristic circRNA junctions in plasma and 72 in urine. Highly-expressed circRNA junctions were validated by qRT-PCR. Longitudinal samples were collected from a subset, demonstrating circRNA expression was stable over time. Lastly, the ratio of circular to linear transcripts was higher in plasma than urine. This study provides a valuable resource for characterization of circRNA in plasma and urine from healthy volunteers, one that can be developed and reassessed as researchers probe the circRNA contents of biofluids across physiological changes and disease states.

Exploring Noninvasive Biomarkers with the miRandola Database: A Tool for Translational Medicine.

Noninvasive biomarkers are required for addressing crucial clinical needs. The ideal biomarker should be easily accessible and provide a unique characteristic for a healthy status or a pathological condition. In the last years, microRNAs (miRNAs) have been proposed as promising tissue-based biomarkers for several diseases such as cancer and cardiovascular diseases. Recently, miRNAs have shown great potential as novel noninvasive biomarkers, due to their high stability in human body fluids such as serum, plasma, and urine. Furthermore, many other noncoding RNAs (ncRNAs) such as long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) have shown to be novel biomarkers as well. The aim of this exciting research field is to offer novel tools, allowing translational scientists to develop new strategies for diagnosis, screening, and monitoring of diseases. In this book chapter, the miRandola database and its applications will be introduced. The database offers the possibility to explore information on ncRNAs as noninvasive biomarkers, manually extracted from scientific literature and public available resources.

Underlying metastasis mechanism and clinical application of exosomal circular RNA in tumors (Review).

Circular RNA (circRNA) is a long non­coding RNA molecule with a closed loop structure lacking a 5'cap and 3'tail. circRNA is stable, difficult to cleave and resistant to RNA exonuclease or RNase R degradation. circRNA molecules have several clinical applications, especially in tumors. For instance, circRNA may be used for non­invasive diagnosis, therapy and prognosis. Exosomes play a crucial role in the development of tumors. Exosomal circRNA in particular has led to increased research interest into tumorigenesis and tumor progression. Additionally, exosomal circRNA plays a role in cell­cell communication. Exosomal circRNA facilitates tumor metastasis by altering the tumor microenvironment and the pre­metastatic niche. Additionally, studies have revealed the mechanism by which exosomal circRNA affects malignant progression through signal transduction. Moreover, exosomal circRNA promotes tumor metastasis by regulating gene expression, RNA transcription and protein translation. In this review, the biological features and clinical application of exosomal circRNA are described, highlighting the underlying mechanisms through which they regulate tumor metastasis. The application of circRNA as clinical diagnostic biomarkers and in the development of novel therapeutic strategies is also discussed.

Differential expression analysis of urinary exosomal circular RNAs in patients with IgA nephropathy.

AIMS: Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease to cause end-stage kidney disease. This study investigated the difference in urinary exosomal circular RNA (circRNA) expression profiles between patients with IgAN and healthy controls (HCs), for better understanding of gene regulation in exosomes of IgAN patients. METHODS: A pairwise comparison of urinary circRNA expression profiles between IgAN patients and HCs was performed using methods, including high-throughput sequencing and quantitative polymerase chain reaction. Moreover, the potential functions of differentially expressed circRNAs (DECs) in IgAN were investigated by gene ontology (GO) enrichment analysis; Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis; and the circRNA-miRNA-mRNA network. RESULTS: We identified 450 upregulated and 26 downregulated circRNAs in the IgAN patients. GO analysis showed that these enriched circRNAs might regulate primary miRNA processing, the ability of angiotensin receptor binding, and stress fibre function. KEGG analysis suggested these DECs may be closely associated with the phosphoinositide-3-kinase-protein kinase B/Akt (PI3K-Akt) signalling pathways. Network analysis revealed the relationship between circRNAs and their target genes. CONCLUSION: The identified DECs may be useful for both researches on molecular aetiology of IgAN and development of potentially novel non-invasive biomarkers of IgAN.

The Research Progression and Clinical Significance of Circular RNAs in Head and Neck Cancers.

With rapid development of science technique and molecular research, a large number of circular RNAs (circRNAs) were discovered. CircRNAs that are a heterogeneous endogenous group of non-coding RNA not only are abundantly and diffusely expressed in mammals but also participate in many biological processes, such as in tumor ingenuity and progress. CircRNAs have rarely open reports in the head and neck cancers (HNC), which are an aggressive malignant tumor with unsatisfactory overall survival rates. The diagnostics and treatments continue to improve while the survival rate of HNC patients has no more obvious improvement. Recent studies that are aimed at exploring the molecular mechanisms of occurrence and progression of circRNAs in HNC provide a valuable insight into potential novel diagnostic and therapeutic approaches. In this review, we summarize the increasing number of published researches on the research progression of circRNAs in HNC, as well as their possible clinical implications on HNC.

Identification of urinary hsa_circ _0137439 as potential biomarker and tumor regulator of bladder cancer.

Cell-free circular RNAs (circRNAs) stably and abundantly exist in body fluids. In this study we aimed to investigate the potential of urinary cell-free circRNAs as a novel class of noninvasive disease biomarkers for diagnosis of bladder cancer. Differentially expressed circRNAs from 10 normal and 10 bladder cancer urine samples were firstly detected by microarray. Hsa_circ_0137439 was then screened and validated in 30 normal and 116 bladder cancer samples. A receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of hsa_circ_0137439. The Kaplan-Meier method was used to evaluate the significance of hsa_circ_0137439 in the prognosis of bladder cancer. We found that hsa_circ_0137439 was significantly upregulated in bladder cancer samples. Moreover, increased expression of hsa_circ_0137439 was correlated with higher tumor stage, higher tumor grade, higher lymph node status, and history of muscle-invasive bladder cancer (MIBC). Also, urinary cell-free hsa_circ_0137439 could not only differentiate bladder cancer from normal controls but also distinguish MIBC from non-muscle-invasive bladder cancer (NMIBC). Additionally, hsa_circ_0137439 in urine supernatant could serve as an independent prognostic predicator of recurrence-free survival and overall survival for patients with bladder cancer. Cell assays showed that hsa_circ_0137439 knockdown contributed to the inhibition of cell proliferation and migration via hsa_circ_0137439/miR-142-5p/ MTDH axis. In conclusion, urinary cell-free hsa_circ_0137439 could be a promising biomarker for tumor diagnosis and prognostic assessment of bladder cancer patients.

Circular RNAs in Urine of Kidney Transplant Patients with Acute T Cell-Mediated Allograft Rejection.

BACKGROUND: Circular RNAs (circRNAs) have recently been described as novel noncoding regulators of gene expression. They are detectable in the blood of patients with acute kidney injury. We tested whether circRNAs were present in urine and could serve as new predictors of outcome in renal transplant patients with acute rejection. METHODS: A global circRNA expression analysis using RNA from urine of patients with acute T cell-mediated renal allograft rejection and control transplant patients was performed. Dysregulated circRNAs were confirmed in a cohort of 62 patients with acute rejection, 10 patients after successful antirejection therapy, 18 control transplant patients without rejection, and 13 stable transplant patients with urinary tract infection. RESULTS: A global screen revealed several circRNAs to be altered in urine of patients with acute rejection. Concentrations of 2 circRNAs including hsa_circ_0001334 and hsa_circ_0071475 were significantly increased. These were validated in the whole cohort of patients. hsa_circ_0001334 was upregulated in patients with acute rejection compared with controls. Concentrations of hsa_circ_0001334 normalized in patients with acute rejection following successful antirejection therapy. hsa_circ_0001334 was associated with higher decline in glomerular filtration rate 1 year after transplantation. CONCLUSIONS: CircRNA concentrations are significantly dysregulated in patients with acute rejection at subclinical time points. Urinary hsa_circ_0001334 is a novel biomarker of acute kidney rejection, identifying patients with acute rejection and predicting loss of kidney function.