MicroRNA role in thyroid cancer pathogenesis.

MicroRNAs (miRNAs) are a class of endogenous, non-coding RNAs approximately 22 nucleotides in length that negatively regulate translation of the protein-coding genes. As such, miRNAs are fundamental mediators of cellular differentiation, proliferation, and survival. Each miRNA may functionally interact with a multitude of target genes to exert various effects on normal physiology to support human health or pathological processes leading to disease conditions, such as cancer. Genome-wide analyses have generated specific miRNA profiles of thyroid cancers (TCs) and identified the up- and down-regulated miRNAs related to various carcinogenesis stages and prognoses. Here, we summarize the recent knowledge on aberrant miRNA expression in the various TCs, including papillary, follicular, and other rare types. In addition, we discuss the significance of miRNA profiles and individual miRNAs in the diagnosis, treatment, and prognosis of these tumors.