Circular RNAs (circRNAs), one type of non-coding RNA, were initially misinterpreted as nonfunctional products of pre-mRNA mis-splicing. Currently, circRNAs have been proven to manipulate the functions of diverse molecules, including non-coding RNAs, mRNAs, DNAs and proteins, to regulate cell activities in physiology and pathology. Accumulating evidence indicates that circRNAs play critical roles in tumor genesis, development, and sensitivity to radiation and chemotherapy. Radiotherapy and chemotherapy are two primary types of intervention for most cancers, but their therapeutic efficacies are usually retarded by intrinsic and acquired resistance. Thus, it is urgent to develop new strategies to improve therapeutic responses. To achieve this, clarification of the underlying mechanisms affecting therapeutic responses in cancer is needed. This review summarizes recent progress and mechanisms of circRNAs in cancer resistance to radiation and chemotherapy, and it discusses the limitations of available knowledge and potential future directions.

中文翻译：

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环状RNA在癌症放疗和化疗耐药中的功能和机制

环状RNA（circRNA）是一种非编码RNA，最初被误解为pre-mRNA错剪的非功能性产物。目前，已证明circRNA可以操纵多种分子的功能，包括非编码RNA，mRNA，DNA和蛋白质，从而调节生理和病理学中的细胞活性。越来越多的证据表明，circRNA在肿瘤的发生，发展以及对放射和化学疗法的敏感性中起着至关重要的作用。放射疗法和化学疗法是大多数癌症的两种主要干预方式，但是它们的治疗效果通常会受到内在和获得性耐药的影响。因此，迫切需要开发新的策略来改善治疗反应。为此，需要澄清影响癌症治疗反应的潜在机制。