Role of Circular RNAs in Liver Diseases

Circular RNAs (circRNAs) are a subclass of noncoding RNAs characterized by their closed-loop structure without terminal 3' or 5' ends. Studies have shown that circRNAs play pivotal roles in the regulation of various cellular processes. These molecules function as microRNA (miRNA) sponges, interact with RNA-binding proteins, and modulate gene transcription. CircRNAs are vital for regulating liver homeostasis, and dysregulation of their expression is correlated with liver diseases such as hepatic fibrosis, steatosis, inflammation, and liver cancer. Elucidating the functional significance of circRNAs in liver diseases is crucial, as this knowledge may facilitate the identification of novel diagnostic biomarkers and therapeutic targets for conditions that contribute significantly to global morbidity and mortality. This review aimed to highlight current research underscoring the functional roles of circRNAs in the molecular pathogenesis and progression of liver diseases, including hepatocellular carcinoma, nonalcoholic fatty liver disease, and liver fibrosis. To provide an updated and comprehensive overview, a literature search was conducted across major scientific databases. This review reveals that circRNAs perform multifaceted functions in liver homeostasis and disease by regulating gene expression through miRNA sponging, interacting with signaling pathways, and influencing cellular processes, including vascularization, metastasis, the cell cycle, apoptosis, cellular stress, metabolic activity, inflammatory responses, and cellular senescence. Despite their pivotal involvement in liver diseases, translating circRNA-based research into clinical practice remains challenging. In conclusion, circRNAs represent an emerging frontier in liver disease research, offering considerable promise for future clinical applications.