Developmental Reprogramming of Myometrial Stem Cells by Endocrine Disruptor Linking to Risk of Uterine Fibroids [ChIP-Seq]

We report that developmental exposure to the endocrine disrupting chemical (EDC) diethylstilbestrol increases the estrogen action in myometrial stem cells (MMSCs), the origin from which UFs originate. The expression of reprogrammed estrogen responsive genes (ERGs) is driven by activated mixed lineage leukemia protein-1 (MLL1) in MMSCs. Deactivation of MLL1 reverses reprogramming of ERG expression. In addition, upregulation of ERGs occurs via DNA hypomethylation mechanism. Furthermore, the secretome of reprogrammed MMSCs enhances the proliferation of differentiated myometrial cells through activation of ß-catenin signaling. This work identifies epigenetic mechanisms of MLL1/DNA methyltransferase- mediated MMSC reprogramming, and EDC exposure epigenetically targets MMSCs and imparts a hormonal imprint on the ERGs resulting in a "hyper-estrogenized" phenotype and increased hormone-dependent risk of UFs. Overall design: Examine the epigenome in MMSCs from 5 month Eker rat myometrium PND 10-12 exposed to DES and VEH