Does ulipristal acetate emergency contraception (ella®) interfere with implantation?

BACKGROUND: Ulipristal acetate (UPA) 30 mg (ella®, HRA-Pharma, Paris, France) acts as an emergency contraceptive (EC) by delaying ovulation. Because it is a selective progesterone receptor modulator, an additional effect on interfering with implantation has been suggested. OBJECTIVE: This review discusses the evidence for, and against, an anti-implantation effect of UPA-EC. SOURCES OF EVIDENCE: Primary research on the effect of UPA, at a relevant dose, on endometrium, implantation, efficacy and pregnancy outcome. RESULTS: UPA-EC does not appear to have a direct effect on the embryo. Changes in endometrial histology are small and not consistent, varying among studies. While UPA-EC affects the profile of gene expression in human endometrium, the findings vary between studies, and it is not clear that these changes affect endometrial receptivity or prevent implantation. UPA at pharmacological concentrations does not appear to have any inhibitory effect on embryo attachment in in vitro systems of human endometrium. UPA-EC is not more effective at preventing pregnancy than chance alone if used after ovulation and does not increase miscarriage rates. CONCLUSIONS: An anti-implantation effect of UPA is highly unlikely at the dose used for EC. Maintaining the warning on the FDA-approved label that "it may also work by preventing implantation to the uterus" might deter some women from using EC, leaving them no option to prevent unwanted pregnancy after unprotected sexual intercourse.

Anti-Tumoral Effects of Anti-Progestins in a Patient-Derived Breast Cancer Xenograft Model.

Breast cancer is a hormone-dependent disease in which estrogen signaling targeting drugs fail in about 10 % due to resistance. Strong evidences highlighted the mitogen role of progesterone, its ligands, and the corresponding progesterone receptor (PR) isoforms in mammary carcinoma. Several PR antagonists have been synthesized; however, some of them are non-selective and led to side or toxic effects. Herein, we evaluated the anti-tumor activity of a commercially available PR modulator, ulipristal acetate (UPA), and a new selective and passive PR antagonist "APR19" in a novel preclinical approach based on patient-derived breast tumor (HBCx-34) xenografted in nude mice. As opposed to P4 that slightly reduces tumor volume, UPA and APR19 treatment for 42 days led to a significant 30 % reduction in tumor weight, accompanied by a significant 40 % retardation in tumor growth upon UPA exposure while a 1.5-fold increase in necrotic areas was observed in APR19-treated tumors. Interestingly, PR expression was upregulated by a 2.5-fold factor in UPA-treated tumors while APR19 significantly reduced expression of both PR and estrogen receptor α, indicating a potential distinct molecular mechanism among PR antagonists. Cell proliferation was clearly reduced in UPA group compared to vehicle conditions, as revealed by the significant reduction in Ki-67, Cyclin D1, and proliferating cell nuclear antigen (PCNA) expression. Likewise, an increase in activated, cleaved poly(ADP-ribose) polymerase (PARP) expression was also demonstrated upon UPA exposure. Collectively, our findings provide direct in vivo evidence for anti-progestin-mediated control of human breast cancer growth, given their anti-proliferative and pro-apoptotic activities, supporting a potential role in breast cancer therapy.

Ulipristal Acetate Inhibits Progesterone Receptor Isoform A-Mediated Human Breast Cancer Proliferation and BCl2-L1 Expression.

The progesterone receptor (PR) with its isoforms and ligands are involved in breast tumorigenesis and prognosis. We aimed at analyzing the respective contribution of PR isoforms, PRA and PRB, in breast cancer cell proliferation in a new estrogen-independent cell based-model, allowing independent PR isoforms analysis. We used the bi-inducible human breast cancer cell system MDA-iPRAB. We studied the effects and molecular mechanisms of action of progesterone (P4) and ulipristal acetate (UPA), a new selective progesterone receptor modulator, alone or in combination. P4 significantly stimulated MDA-iPRA expressing cells proliferation. This was associated with P4-stimulated expression of the anti-apoptotic factor BCL2-L1 and enhanced recruitment of PRA, SRC-1 and RNA Pol II onto the +58 kb PR binding motif of the BCL2-L1 gene. UPA decreased cell proliferation and repressed BCL2-L1 expression in the presence of PRA, correlating with PRA and SRC1 but not RNA Pol II recruitment. These results bring new information on the mechanism of action of PR ligands in controlling breast cancer cell proliferation through PRA in an estrogen independent model. Evaluation of PR isoforms ratio, as well as molecular signature studies based on PRA target genes could be proposed to facilitate personalized breast cancer therapy. In this context, UPA could be of interest in endocrine therapy. Further confirmation in the clinical setting is required.

Bone protection by estrens occurs through non-tissue-selective activation of the androgen receptor.

The use of estrogens and androgens to prevent bone loss is limited by their unwanted side effects, especially in reproductive organs and breast. Selective estrogen receptor modulators (SERMs) partially avoid such unwanted effects, but their efficacy on bone is only moderate compared with that of estradiol or androgens. Estrens have been suggested to not only prevent bone loss but also exert anabolic effects on bone while avoiding unwanted effects on reproductive organs. In this study, we compared the effects of a SERM (PSK3471) and 2 estrens (estren-alpha and estren-beta) on bone and reproductive organs to determine whether estrens are safe and act via the estrogen receptors and/or the androgen receptor (AR). Estrens and PSK3471 prevented gonadectomy-induced bone loss in male and female mice, but none showed true anabolic effects. Unlike SERMs, the estrens induced reproductive organ hypertrophy in both male and female mice and enhanced MCF-7 cell proliferation in vitro. Estrens directly activated transcription in several cell lines, albeit at much higher concentrations than estradiol or the SERM, and acted for the most part through the AR. We conclude that the estrens act mostly through the AR and, in mice, do not fulfill the preclinical efficacy or safety criteria required for the treatment or prevention of osteoporosis.

Synthesis and relative binding affinity to human steroid receptors of substituted 3-aryloxycoumarins.

The synthesis of a set of substituted 3-aryloxycoumarins was performed. The study of the relations between their structure and their relative binding affinity to human androgen, progesterone, alpha and beta estrogen receptors was achieved.

A functional androgen receptor is not sufficient to allow estradiol to protect bone after gonadectomy in estradiol receptor-deficient mice.

Although the role of estradiol in maintaining bone mass is well established, the relative contributions of the estradiol receptors ERalpha and ERbeta and of the androgen receptor (AR) remain controversial. To determine the role of ERalpha-mediated, ERbeta-mediated, and non-ER-mediated mechanisms in maintaining bone mass, gonadectomy and estradiol treatment were studied in ER-knockout mice. Estradiol treatment of ovariectomized ERalphabeta(-/-) mice failed to prevent bone loss, precluding significant effects of estradiol on bone through non-ER-signaling pathways. In contrast, estradiol prevented ovariectomy-induced bone loss in ERbeta(-/-) mice, as in WT males and females, indicating that ERalpha is the major mediator of estradiol effects in bone. No response of bone to estradiol was detected in orchidectomized ERalpha(-/-) mice, suggesting estradiol cannot protect bone mass via the AR in vivo. In contrast to female ERalphabeta(-/-) and male ERalpha(-/-) mice, female ERalpha(-/-) mice were partially protected against ovariectomy-induced bone loss by estradiol, confirming that ERbeta mediates estradiol effects in bone, but only in females and with a lower efficacy than ERalpha. We conclude that ERalpha is the main effector of estradiol's protective function in bone in both male and female mice, and that, in its absence, AR is not sufficient to mediate this response.