Hepatocellular carcinoma (HCC) is one of the most common malignancies globally. Despite aggressive and multimodal treatment regimens, the overall survival of HCC patients remains poor. Circular RNAs (circRNAs) are noncoding RNAs (ncRNAs) with covalently closed structures and tissue- or organ-specific expression patterns in eukaryotes. They are highly stable and have important biological functions, including acting as microRNA sponges, protein scaffolds, transcription regulators, translation templates and interacting with RNA-binding protein. Recent advances have indicated that circRNAs present abnormal expression in HCC tissues and that their dysregulation contributes to HCC initiation and progression. Furthermore, researchers have revealed that some circRNAs might serve as diagnostic biomarkers or drug targets in clinical settings. In this review, we systematically evaluate the characteristics, biogenesis, mechanisms and functions of circRNAs in HCC and further discuss the current shortcomings and potential directions of prospective studies on liver cancer-related circRNAs. CircRNAs are a novel class of ncRNAs that play a significant role in HCC initiation and progression, but their internal mechanisms and clinical applications need further investigation.

中文翻译：

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环状RNA：肝癌的特征、生物发生、机制和功能

肝细胞癌（HCC）是全球最常见的恶性肿瘤之一。尽管采用了积极的多模式治疗方案，但 HCC 患者的总体生存率仍然很低。环状 RNA (circRNA) 是非编码 RNA (ncRNA)，在真核生物中具有共价闭合结构和组织或器官特异性表达模式。它们高度稳定并具有重要的生物学功能，包括充当 microRNA 海绵、蛋白质支架、转录调节剂、翻译模板以及与 RNA 结合蛋白相互作用。最近的进展表明，circRNA 在 HCC 组织中表现出异常表达，并且它们的失调有助于 HCC 的发生和进展。此外，研究人员还发现，一些 circRNA 可能在临床环境中作为诊断生物标志物或药物靶点。在这次审查中，我们系统地评估了肝癌相关circRNAs的特征、生物发生、机制和功能，并进一步讨论了肝癌相关circRNAs前瞻性研究的当前不足和潜在方向。circRNAs 是一类在 HCC 发生和进展中起重要作用的新型 ncRNAs，但其内部机制和临床应用需要进一步研究。