miRNAs and estrogen action

MicroRNAs (miRNAs) are short, noncoding RNAs that generally base-pair within the 3' untranslated region of target mRNAs causing translational inhibition and/or mRNA degradation. Estradiol (E-2) and other estrogen receptor (ER) ligands suppress or stimulate miRNA expression in human breast cancer cells, endometrial cells, rat mammary gland, and mouse uterus, and post-translationally regulate protein expression. Aberrant miRNA expression is implicated in estrogen-related breast and endometrial cancers, and several miRNAs downregulate ER alpha. The role of estrogen-regulated miRNA expression, the target genes of these miRNAs, and the role of miRNAs in health and disease is a 'hot' area of research that will yield new insight into molecular mechanisms of estrogen action.