Abstract
Circular RNAs (circRNAs) are a novel class of non-coding RNAs primarily generated through a back-splicing processes. These molecules exhibit extensive expression across various tissues, indicating their significant role in numerous biological processes, particularly in complex diseases such as cancer. Based on their origin, structure, and biogenesis, circular RNAs are categorized into exonic circRNAs (ecirc-RNAs), circular intronic RNAs (ci-RNAs), or exonic-intronic circRNAs (EIci-RNAs). Due to their covalently closed-loop configuration, it is necessary to develop specialized techniques to study them. CircRNAs are known to function as protein and microRNA sponges, regulate transcription, interact with RNA-binding proteins (RBPs), and, in rare cases, serve as templates for translation. In this review, we provide an overview of circRNA features, biogenesis, and functions. In addition, we summarize molecular methods for studying them and explain their significant roles in malignancies.