Abstract

MicroRNAs (miRNAs) are small non-coding RNA molecules, approximately 20–25 nucleotides long, that regulate gene expression by modulating mRNA stability and protein synthesis. Since their discovery in Caenorhabditis elegans in 1993, miRNAs have emerged as critical players in virtually all biological processes, including development, immunity, and disease progression. Thousands of miRNAs have been identified across multicellular organisms, highlighting their evolutionary importance.
This review explores the biogenesis and mechanisms of miRNA-mediated gene regulation, emphasizing their dual roles as oncogenes and tumor suppressors in cancer, as well as their involvement in cardiovascular, inflammatory, and genetic diseases. For example, miR-21 is linked to poor prognosis in various cancers, while miR-146a modulates inflammation in chronic conditions like atopic dermatitis and rheumatoid arthritis.