The role of extracellular vesicle microRNAs in cancer biology.

microRNAs (miRNAs) constitute a large family of small, approximately 20-22 nucleotide non-coding RNAs that regulate the expression of target genes, mainly at the post-transcriptional level. Multiple studies report that miRNAs are involved in homeostatic maintenance and that aberrant expression of miRNAs is often observed in various types of diseases, including cancer. In cancer biology, miRNAs exert functional roles in tumor initiation, drug resistance, and metastasis.