Increased HSD11β1 Expression in Human Leiomyomatous Uteri: Implication for Enhanced Glucocorticoid Signaling

Abstract: FK506-binding-protein-51 (FKBP51) is a glucocorticoid-induced co-chaperone protein previously shown to bind glucocorticoid receptor (GR), inhibiting its transcriptional activity. We previously found increased FKBP51 levels in uterine leiomyoma versus paired myometrium. To test the hypothesis that elevated FKBP51 levels contribute to leiomyoma pathogenesis by altering GR signaling. Material Method: RNA-sequencing was performed in leiomyoma cell cultures transfected with scrambled or FKBP5-siRNA for 48-h, then treated with vehicle or dexamethasone (DEX) for 24-h. Differentially expressed genes, including HSD11B1, CNN1, and LAMA2 were analyzed by qPCR. Hydroxysteroid 11-beta dehydrogenase 1 (HSD11β1) expression was analyzed in leiomyoma, leiomyoma-adjacent paired myometrium, myometrium from patients without leiomyoma, and human endometrial stromal cells (HESC) by qPCR and immunohistochemistry in women with or without uterine leiomyoma. HSD11B1 mRNA and protein levels in leiomyoma, paired and normal myometrium, and HESC cells and tissue. Results: HSD11β1 expression was higher in paired myometrial and leiomyoma tissues versus normal myometrium (P<0.02). DEX treatment increased HSD11B1 transcription in normal myometrial and HESC cultures, but to a significantly greater extent in leiomyoma. However, FKBP5-silencing blunted DEX-induced HSD11B1 transcription. DEX-treatment reduced LAMA2 and increased CNN1 levels (coding for extracellular matrix and smooth muscle proteins, respectively) in FKBP5-silenced versus scrambled-siRNA leiomyoma cultures. Conclusions: FKBP51 not only inhibits but can augment GR-mediated transcription. Importantly, FKBP51-GR interactions increase HSD11B1 levels in leiomyoma cells, generating a pathological FKBP51-GR-HSD11β1 circle, altering transcription of downstream extracellular matrix and smooth muscle genes to induce a myofibroblast phenotype, thereby possibly contributing to leiomyoma pathogenesis.