The expression and ovarian steroid regulation of endometrial micro-RNAs.

MicroRNAs (miRNAs) which regulate gene expression stability displayed an aberrant expression profile in ectopic endometrium (ECE) as compared to eutopic (EUE) and normal endometrium (NE). We assessed the expression of miR-17-5p, miR-23a, miR-23b and miR-542-3p, their predicted target genes, steroidogenic acute regulatory protein, aromatase and cyclooxygenase-2, and influence of ovarian steroids on their expression in endometrial stromal (ESC) and glandular epithelial cells (GEC). The results indicated a lower expression of miR-23b and miR-542-3p and higher level of miR-17-5p in paired ECE and EUE as compared with NE. These levels were elevated and inversely correlated with the level of expression of their respective target genes in ECE. The expression of these miRNAs and genes was differentially regulated by 17beta- estradiol, medroxyprogesterone acetate, ICI-182780 and RU-486, or their respective combinations in ESC and GEC. We concluded that altered expression of specific miRNAs in ECE, affecting the stability of their target genes expression, has direct implications in pathogenesis of endometriosis.