Circular RNA (circRNA) is a large class of covalently closed circRNA. As a member of competitive endogenous RNA, it participates in the regulation of circRNA-miRNA-mRNA network and plays an important role in the regulation of physiology and pathology. CircRNA is produced by the reverse splicing of exon, intron or both, forming exon or intron circRNA. Studies have shown that circRNA is a ubiquitous molecule, which exceeds the linear mRNA distributed in human cells. Because of its covalent closed-loop structure, circRNA is resistant to RNase R, which is more stable than linear mRNA; circRNA is highly conserved in different species. It was found that circRNA competitively adsorbs miRNA, as a miRNA sponge, to involve in the expression regulation of a variety of genes and plays an important role in tumor development, invasion, metastasis and other processes. These molecules offer new potential opportunities for therapeutic intervention and serve as biomarkers for diagnosis. In this paper, the origin, characteristics and functions of circRNA and its role in tumor development, invasion and metastasis, diagnosis and prognosis are reviewed.

中文翻译：

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circRNAs 在具有功能诊断和预后预测功能的癌症精准医学中的力量和前景。

环状RNA（circRNA）是一大类共价闭合的环状RNA。作为竞争性内源RNA的一员，参与circRNA-miRNA-mRNA网络的调控，在生理和病理调控中发挥重要作用。circRNA 是通过外显子、内含子或两者的反向剪接产生的，形成外显子或内含子的 circRNA。研究表明，circRNA是一种无处不在的分子，其超过了分布在人体细胞中的线性mRNA。由于其共价闭环结构，circRNA对RNase R具有抗性，比线性mRNA更稳定；circRNA在不同物种中高度保守。发现circRNA竞争性吸附miRNA，作为miRNA海绵，参与多种基因的表达调控，在肿瘤发生、侵袭、转移和其他过程。这些分子为治疗干预提供了新的潜在机会，并作为诊断的生物标志物。本文就circRNA的起源、特征、功能及其在肿瘤发生发展、侵袭转移、诊断和预后中的作用进行综述。