Abstract: Objective To explore the pathogenic roles of miR-21, estrogen (E2), and estrogen receptor (ER) in adenomyosis. Methods We examined the expression levels of miR-21 in specimens of adenomyotic tissue and benign cervical lesions using qRT-PCR. In primary cultures of cells isolated from the adenomyosis lesions, the effect of ICI82780 (an ER inhibitor) on miR-21 expression levels prior to E2 activation or after E2 deprivation were examined with qRT-PCR. We further assessed the effects of a miR-21 mimic or an inhibitor on proliferation, apoptosis, migration and autophagy of the cells. Results The expression level of miR-21 was significantly higher in adenomyosis tissues than in normal myometrium (P<0.05). In the cells isolated from adenomyosis lesions, miR-21 expression level was significantly higher in E2 activation group than in ER inhibition+E2 activation group and the control group (P<0.05); miR-21 expression level was significantly lower in cells in E2 deprivation+ER inhibition group than in E2 deprivation group and the control group (P<0.05). The adenomyosis cells transfected with miR-21 inhibitor showed inhibited proliferation and migration, expansion of mitochondrial endoplasmic reticulum, increased lysosomes, presence of autophagosomes, and increased cell apoptosis, while transfection of the cells with the miR-21 mimic produced the opposite effects. Conclusion MiR- 21 plays an important role in promoting proliferation, migration, and anti-apoptosis in adenomyosis cells by altering the cell ultrastructure, which may contribute to early pathogenesis of the disease. In addition to binding with E2, ER can also regulate miR-21 through other pathways to participate in the pathogenesis of adenomyosis, thus having a stronger regulatory effect on miR-21 than E2.

Key words: adenomyosis; miR-21; estrogen; estrogen receptor