Androgen-metabolizing enzymes: A structural perspective

Targeting aromatase to restrain oestrogen production and developing efficacious interventions against ER-positive cancer

Being the most frequently diagnosed disease, breast cancer is mainly classified as ER+ cancers due to the detection of estrogen receptor (ER) expression. Irrespetive of the successes achieved in the treatment of ER+ cancers by the use of selective estrogen receptor modulator (SERM) drugs like tamoxifen, resistance to the drug is a major clinical obstacle. Working on alternative treatment approaches, here, on the basis of mode of action of aromatase for the conversion of androstenedione to oestrogen, a series of compounds was developed. Results of all the experiments performed with these compounds led to the identification of three highly potent compounds 5d, 5e and 7d with their IC50 61.0, 83.0 and 54.0 nM for aromatase. Indicating their effectiveness in the treatment of ER+ cancers, appreciable tumor growth inhibitory activities of these compounds were observed against breast cancer cell lines. Further, the physico-chemical experiments including plasma protein binding, HSA binding, kinetic studies, solubility, ADME properties and molecular modelling studies supported the drug like features of the compounds.

Angiotensin-(1-7), Angiotensin-Converting Enzyme 2 and Mas Receptor in Rat Polycystic Ovaries

BACKGROUND

Hyperandrogenism is a pivotal mediator in the pathogenesis of the polycystic ovary syndrome (PCOS), but the mechanisms of androgen excess in this condition are not fully understood. Angiotensin (Ang)-(1-7) is an active peptide of the renin-angiotensin system (RAS) that stimulates ovarian follicular growth and testosterone release in vitro.

OBJECTIVE

To investigate whether Ang-(1-7), its receptor Mas and angiotensin-converting enzyme 2 (ACE2), the enzyme that converts Ang II into Ang-(1-7), are expressed in rat polycystic ovaries (PCO) and thus if this peptide system might be associated with excess androgen production in PCO.

METHODS

A rat model that shares some features of PCOS such as disruption of folliculogenesis and multiple ovarian cyst formation was used in the study.

RESULTS

We found reduced levels of Ang-(1-7) and Mas receptor in PCO compared to normal ovaries. Also, ACE2 mRNA expression was reduced in PCO compared to ovaries of control rats (p < 0.05). PCO had high levels of estrogen and testosterone and increased mRNA for upstream enzymes of the steroidogenic cascade, but not of P450 aromatase.

CONCLUSION

These findings suggest that the ovarian ACE2-Ang-(1-7)-Mas receptor axis is inhibited and therefore may not be a co-factor of excess testosterone production in rat PCO.

Intracrine Regulation of Estrogen and Other Sex Steroid Levels in Endometrium and Non-gynecological Tissues; Pathology, Physiology, and Drug Discovery

Our understanding of the intracrine (or local) regulation of estrogen and other steroid synthesis and degradation expanded in the last decades, also thanks to recent technological advances in chromatography mass-spectrometry. Estrogen responsive tissues and organs are not passive receivers of the pool of steroids present in the blood but they can actively modify the intra-tissue steroid concentrations. This allows fine-tuning the exposure of responsive tissues and organs to estrogens and other steroids in order to best respond to the physiological needs of each specific organ. Deviations in such intracrine control can lead to unbalanced steroid hormone exposure and disturbances. Through a systematic bibliographic search on the expression of the intracrine enzymes in various tissues, this review gives an up-to-date view of the intracrine estrogen metabolisms, and to a lesser extent that of progestogens and androgens, in the lower female genital tract, including the physiological control of endometrial functions, receptivity, menopausal status and related pathological conditions. An overview of the intracrine regulation in extra gynecological tissues such as the lungs, gastrointestinal tract, brain, colon and bone is given. Current therapeutic approaches aimed at interfering with these metabolisms and future perspectives are discussed.