Effect of ulipristal acetate on gene expression profile in endometrial cells in culture and in vivo upon post-ovulatory administration in fertile women.

PURPOSE To analyse the effect of ulipristal acetate (UPA) as emergency contraception (EC) on the gene expression of human endometrial cell line (HEC-1A) and endometrium from fertile women treated with UPA after ovulation. MATERIALS AND METHODS HEC-1A cells were treated with UPA, and endometrial tissue from four healthy women was collected in cycles before, during and 2 months after post-ovulation pill intake. Ovulation and luteal phase were monitored, and endometrial biopsies were obtained at day LH + 7 in each cycle. In all cases, we analysed the expression profile of 192 genes associated to endometrial receptivity. RESULTS We observed a significant change in total transcriptomic activity of UPA-treated HEC-1A cells compared to controls. In vivo, we also observed a trend to down-regulation of genes in the UPA-treated cycle that was partially restored in the post-treatment cycle. Altogether, our results supported a partially reversible effect of UPA in gene expression associated with uterine receptivity. CONCLUSIONS When UPA was administered after ovulation, it seems to induce a down-regulation of the main genes involved in conditioning the endometrium for implantation. This effect is partially restored two months after pill intake. The action of UPA on the endometrium for users of EC should be further investigated.