**Background**
Estrogen receptors play a critical role in the regulation of various physiological processes, including the maintenance of the female reproductive system and the modulation of bone density. Dysregulation of estrogen signaling is often associated with menstrual disorders and menopausal symptoms, making the estrogen receptor a primary target for hormone replacement therapy and the study of endocrine-related pathologies. In the context of oncology, the role of estrogen in promoting the growth of certain breast cancer subtypes further emphasizes the need for precise pharmacological tools to study these pathways. Therefore, we will introduce a synthetic estrogen proagent – Mestranol.
**Definition**
Mestranol is an inactive proagent that acts as an estrogen receptor agonist upon its conversion to the biologically active ethinyl estradiol (EE). According to the Mestranol technical information, it is a low potency synthetic estrogen with a molecular weight of 310.43 and a specific Mestranol formula of C21H26O2.
**In Vitro Studies**
Mestranol is utilized as a click chemistry reagent containing an Alkyne group, allowing it to undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with azide-containing molecules. Regarding Mestranol biological activity, in vitro studies have demonstrated that it is significantly more stable than 17β-Estradiol in hepatoma cell cultures. Specifically, Mestranol (10 μM; 6 days) stimulates the growth of ER-positive MCF-7 WS8 cells up to 250% of control levels, an effect that can be partially reversed by tamoxifen. Conversely, in Hep G2 hepatoma cells, Mestranol (10 μM; 6 days) inhibits the growth of Hep 3B cells by 40% compared to control cells; this inhibitory effect is additive when combined with tamoxifen. Additionally, the antiproliferative activity of Mestranol against human MCF7 cells has been assessed, yielding an IC50 value of 40 nM when incubated for 6 days via SRB assay. In vivo, Mestranol can be combined with a progestin for the research of menstrual disorders or menopausal hormones. In conclusion, Mestranol is a versatile synthetic estrogen proagent and click chemistry tool suitable for research in hormone-dependent disorders and Mestranol Cancer studies.
Keywords
Mestranol, 72-33-3, Estrogen Receptor/ERR, prodrug, ethinyl estradiol, menopausal hormone, menstrual disorder, MCF-7, Hep G2, hepatoma, Inhibitor, inhibitor, inhibit
References
[1] H Kappus, et al. Affinity of ethynyl-estradiol and mestranol for the uterine estrogen receptor and for the microsomal mixed function oxidase of the liver. J Steroid Biochem. 1973 Mar;4(2):121-8.
[2] J W Goldzieher, et al. Pharmacokinetics of ethinyl estradiol and mestranol. Am J Obstet Gynecol. 1990 Dec;163(6 Pt 2):2114-9.
[3] S Y Jiang, et al. Tamoxifen inhibits hepatoma cell growth through an estrogen receptor independent mechanism. J Hepatol. 1995 Dec;23(6):712-9.