Exposure to Phthalates and Alternative Plasticizers Is Associated with Methylation Changes of ESR1 and PGR in Uterine Leiomyoma: The ELENA Study

Abstract

Uterine leiomyomas are estrogen-dependent benign tumors with unknown etiologies. Phthalates are endocrine-disrupting chemicals and ubiquitous in the environment; thus, it has been suggested that they play a role in the development of uterine leiomyoma. We aimed to investigate whether the pathogenesis of uterine leiomyoma is related to methylation changes in promoter regions of estrogen receptor alpha (ESR1) and progesterone receptor (PGR) genes in response to phthalates and alternative plasticizers exposure. Urinary concentrations of 20 phthalate metabolites and seven metabolites of di-2-ethylhexyl terephthalate (DEHTP) and di (isononyl) cyclohexane-1,2-dicarboxylate (DINCH) were measured by UHPLC-MS/MS in thirty leiomyoma patients, who provided both paired leiomyoma and myometrium tissues. Methylation levels of ESR1 and PGR were analyzed by pyrosequencing assay. A total of 12 phthalate metabolites and 5 alternative metabolites (3 DEHTP and 2 DINCH) were detected >70% among study participants. The methylation of ESR1 and PGR were significantly lower in leiomyoma tissues compared to those in myometrium (18.10 +/- 4.41 vs. 28.72 +/- 4.95; 2.32 +/- 0.81 vs. 3.27 +/- 0.56, respectively). ESR1 methylation in leiomyoma was negatively associated with mono-2-carboxylmethyl-hexyl phthalate (2cx-MMHP) and mono-3-carbocyl-propyl phthalate (MCPP) after adjusting for confounding factors. However, 1-mono-2-ethyl-5-oxohexyl-benzene-1,4-dicarboxylate (5OXO-MEHTP), one of the alternatives, showed positive association with ESR1 methylation in leiomyoma. PGR methylation in leiomyoma was significantly associated with mono butyl phthalate (MnBP), but negatively associated with cyclohexane-1,2-dicarboxylate-mono-7-hydroxy-4-methyl-heptyl ester (cx-MINCH). Our results suggest that phthalates exposure may contribute to leiomyoma pathogenesis via ESR1 and PGR methylation changes.