Expression profiles, biological functions and clinical significance of circRNAs in bladder cancer

Abstract

Circular RNAs (circRNAs), which are single-stranded closed-loop RNA molecules lacking terminal 5′ caps and 3′ poly(A) tails, are attracting increasing scientific attention for their crucial regulatory roles in the occurrence and development of various diseases. With the rapid development of high-throughput sequencing technologies, increasing numbers of differentially expressed circRNAs have been identified in bladder cancer (BCa) via exploration of the expression profiles of BCa and normal tissues and cell lines. CircRNAs are critically involved in BCa biological behaviours, including cell proliferation, tumour growth suppression, cell cycle arrest, apoptosis, invasion, migration, metastasis, angiogenesis, and cisplatin chemoresistance. Most of the studied circRNAs in BCa regulate cancer biological behaviours via miRNA sponging regulatory mechanisms. CircRNAs have been reported to be significantly associated with many clinicopathologic characteristics of BCa, including tumour size, grade, differentiation, and stage; lymph node metastasis; tumour numbers; distant metastasis; invasion; and recurrence. Moreover, circRNA expression levels can be used to predict BCa patients’ survival parameters, such as overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS). The abundance, conservation, stability, specificity and detectability of circRNAs render them potential diagnostic and prognostic biomarkers for BCa. Additionally, circRNAs play crucial regulatory roles upstream of various signalling pathways related to BCa carcinogenesis and progression, reflecting their potential as therapeutic targets for BCa. Herein, we briefly summarize the expression profiles, biological functions and mechanisms of circRNAs and the potential clinical applications of these molecules for BCa diagnosis, prognosis, and targeted therapy.

CircRUNX1 Drives Immune Evasion and anti-PD1 Immunotherapy Resistance in Lung Adenocarcinoma by the miR-4739/PCSK9/MHC I Axis

“…However, the application of anti-PD-1 immunotherapy in LUAD is limited by the primary or acquired drug resistance [23,24]. Recently, circRNAs have been reported to play vital roles in the tumorigenesis and progression of tumors [25,26]. Previous studies have identi ed several irregular expressed circRNAs in LUAD that are dysregulated in LUAD tissues and function as tumor suppressor genes or oncogenes.…”

“…Recent studies have con rmed that circRNAs are participate in the progression and immune evasion of various cancers via acting as miRNA sponges, therefore, modulating protein translation [11,25]. In this study, we used StarBase v3.0 to predict the potential miRNAs interaction with circRUNX1, then con rmed by biotin-coupled probe pull-down, AGO2-mediated RIP, and dual luciferase reporter assays.…”

Non-Coding RNAs in Pancreatic Cancer Diagnostics and Therapy: Focus on lncRNAs, circRNAs, and piRNAs

“…In addition to the microarray technique used for circRNA profiling, high-throughput circRNA-sequencing has also been utilized for circRNA expression profiling [129,130]. We have conducted a circRNA-sequencing experiment to obtain the circRNA expression profiles before and after thymoquinone treatment in pancreatic cancer cells.…”

Circular RNA: A novel type of biomarker for glioma (Review)

“…Recent studies have demonstrated that circRNAs are strongly associated with the clinicopathological characteristics of glioma, and they may serve as diagnostic and prognostic biomarkers ( 32 , 92 , 110 ). Previous studies indicated that the closed-ring structure stabilizes circRNAs in plasma and tissues, and protects them from the enzymatic activity of exonucleases ( 28 , 50 ); therefore, the unique structure of circRNAs may be a potential advantage for their use as biomarkers for the diagnosis and prognosis of glioma. Qu et al ( 111 ) revealed that circ_0079593 could be considered an independent prognostic factor for patients with glioma based on multivariate analysis.…”

“…circRNAs are a type of ncRNA characterized by a circular configuration that consists of either prototypical spliceosome-mediated or lariat-type splicing, which provides a strong stability and resistance to RNases ( 28 , 29 ). Numerous studies have shown that several circRNAs are abnormally expressed in human glioma and may be associated with the carcinogenesis of glioma.…”