Progesterone supplementation after postovulatory mifepristone reduce changes in human endometrial gene expression

IN BRIEF: Progesterone supplementation reverses 83% of transcript changes in the secretory endometrium induced by postovulatory mifepristone, potentially mitigating its antiprogestogenic effects. ABSTRACT: Mifepristone (RU486) antagonizes progesterone signaling in human endometrium interfering in the secretory phenotype after estradiol priming. The objective of the present study was to determine effect in the endometrial transcript profile of progesterone supplementation after the administration of 200 mg of the antiprogestin mifepristone 48 h after the LH peak (LH+2, LH+0 = LH peak). Endometrial samples were obtained on LH+7 after vaginal administration of micronized progesterone 200 mg/day for 3 days in nine women of proven fertility, each one contributing with one cycle treated with progesterone and another with a placebo. In addition, endometrial samples were obtained in LH+7 from a subgroup of four women with no administration of mifepristone, with each one contributing with one cycle treated with vaginal progesterone supplementation or placebo as a reference. RNA-seq was used to identify transcripts significantly regulated under the administration of progesterone vs placebo with or without postovulatory mifepristone. We observed that 713 transcripts changed significantly in the endometrium under mifepristone after progesterone supplementation in group A. Of these, progesterone reversed approximately 83% of the transcripts affected by mifepristone in the secretory endometrium. Bioinformatic analyses revealed that these transcripts were enriched in genes associated with mitochondrial function, particularly oxidative phosphorylation. In addition, NR2C2 and DLX1 were identified as potential transcription factors that may mediate the effects of progesterone in the endometrium. We conclude that progesterone supplementation after postovulatory mifepristone administration can reverse the antiprogestogenic effects for most of the affected endometrial transcripts.