MicroRNA in various aspects of cancer development

MicroRNAs (miRNAs) are small (18-25 nucleotides) noncoding RNA molecules that bind to partially complementary mRNA sequences, resulting in target degradation or translation inhibition. A single miRNA can influence the expression of hundreds of target genes, and miRNAs have been implicated as key molecules in various diseases, including cancer. Many studies have shown that the miRNAs play an important role in cancer cells and tumor microenvironment and may be biomarkers for early detection and therapeutic targets for various cancers. Recently, relationships between miRNAs and immunocheckpoint molecules have been focused on as new tumor progression associated mechanisms. As for biomarkers, cell-free miRNAs detected in body fluids (circulating miRNAs) have attached the attention of researchers due to their potential as tumor-specific and non-invasive biomarkers. In terms of strategies to use miRNAs as therapeutic targets, developments of tissue specific delivery systems, including lipid nanoparticles or exosome vectors, are progressing. Here we will review the mechanisms and clinical uses of miRNAs in cancer.