Emerging roles of CircRNA-miRNA networks in cancer development and therapeutic response.

The complex interplay of epigenetic factors is essential in regulating the hallmarks of cancer and orchestrating intricate molecular interactions during tumor progression. Circular RNAs (circRNAs), known for their covalently closed loop structures, are non-coding RNA molecules exceptionally resistant to enzymatic degradation, which enhances their stability and regulatory functions in cancer. Similarly, microRNAs (miRNAs) are endogenous non-coding RNAs with linear structures that regulate cellular biological processes akin to circRNAs. Both miRNAs and circRNAs exhibit aberrant expressions in various cancers. Notably, circRNAs can function as sponges for miRNAs, influencing their activity. The circRNA/miRNA interaction plays a pivotal role in the regulation of cancer progression, including in brain, gastrointestinal, gynecological, and urological cancers, influencing key processes such as proliferation, apoptosis, invasion, autophagy, epithelial-mesenchymal transition (EMT), and more. Additionally, this interaction impacts the response of tumor cells to radiotherapy and chemotherapy and contributes to immune evasion, a significant challenge in cancer therapy. Both circRNAs and miRNAs hold potential as biomarkers for cancer prognosis and diagnosis. In this review, we delve into the circRNA-miRNA circuit within human cancers, emphasizing their role in regulating cancer hallmarks and treatment responses. This discussion aims to provide insights for future research to better understand their functions and potentially guide targeted treatments for cancer patients using circRNA/miRNA-based strategies.