Circular RNAs: A key modulator of established cancer hallmarks.

Cancer encompasses a diverse range of disease conditions marked by the uncontrolled growth of abnormal cells and is often associated with high recurrence rates. The development and progression of cancer are closely linked to the disruption of key molecular pathways that regulate cellular and tissue homeostasis. Among the various molecular players involved, circular RNAs (circRNAs) have gained increasing attention from the scientific community because of their aberrant expression in various cancer types, leading to its progression and development. CircRNAs represent a distinct class of covalently closed RNA with distinct tissue- and cell-specific expression profiles and are essential for controlling key cellular processes. It has emerged as a crucial regulatory molecule that contributes to numerous hallmarks of cancer, such as enhanced cell proliferation, growth suppression evasion, resistance to cell death, induction of angiogenesis, invasion and metastasis, maintenance of cancer stem cells, immune evasion, metabolic reprogramming, promotion of inflammation, impairment of DNA damage, genomic instability, non-mutational epigenetic reprogramming, and therapeutic resistance. This review aims to enhance our understanding on the role of circRNAs on several cancer hallmarks and promote further research into their underlying mechanism of action, to identify and utilize them as potential therapeutic strategies.