Estradiol (E2) is one of the most important hormones supporting the growth and evolution of breast cancer. Consequently, to block this hormone before it enters the cancer cell, or in the cell itself, has been one of the main targets in recent years. In the present study we explored the effect of Medrogestone (Prothil) on 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activities of the hormone-dependent MCF-7 and T-47D human breast cancer cell lines. Using physiological doses of estrone ([3H]-E1: 5 x 10(-9) mol/l) this estrogen is converted in a great proportion to E2 in both cell lines. After 24 h of the cell culture, Medrogestone significantly inhibits this transformation in a dose-dependent manner by 39% and 80% at 5 x 10(-8) M and 5 x 10(-5) M, respectively in T-47D cells; the effect is less intense in MCF-7 cells: 25% and 55% respectively. The IC50 values are 0.45 micromol/l in T-47D and 17.36 micromol/l in MCF-7 cells. It is concluded that the inhibition provoked by Medrogestone on the reductive 17beta-HSD activity involved in the local biosynthesis of the biologically active estrogen estradiol, may constitute a new therapeutic approach for the treatment of breast cancer.

The diversity of function that sex steroids have proven to have in the female body, gives them a position of central importance in gynaecology. Scientific research demonstrates not only the well known genital functions of sexual steroids, furthermore, various extragenital organs are influenced and modulated by ovarian hormones. Therefore, the general benefit of HRT for the female organism becomes clearer and the clinical management of menopause is developing to a broad new discipline, the gender specific medicine. In clinical practise, phytosteroids are claimed by the patient and therefore, also of high interest for the scientific research. Also, tissue specificity of the endocrine treatment and the biological relevance of different steroid receptors of HRT are discussed, leading to the development of new HrT preparations. Individualisation, the tailoring of HRT, according to the patients needs, and low dose steroids management, will also become an important aspect in the recommendations for estrogen and progestin replacement therapy.

In the present study, we explored the effect of the progestin medrogestone on the sulfatase and sulfotransferase activities in the hormone-dependent MCF-7 and T-47D human breast cancer cell lines. After 24 h incubation at 37 degrees C of physiological concentrations of estrone sulfate ([3H]-E1S: 5x10(-9) mol/l), it was observed that this estrogen was converted in a great proportion to E2 in both cell lines. Medrogestone significantly inhibits this transformation, at all the concentrations tested (5x10(-8) to 5x10(-5) mol/l), in both cell lines. The IC50 values were 1.93 micromol/l and 0.21 micromol/l in MCF-7 and T-47D cells, respectively. In another series of studies, after 24 h incubation at 37 degrees C of physiological concentrations of estrone ([3H]-E1: 5x10(-9) mol/l), the sulfotransferase activity was detectable in both cell lines. Estrogen sulfates (ES) are found exclusively in the culture medium, which suggests that as soon as they are formed they are excreted into the medium. Medrogestone has a biphasic effect on sulfotransferase activity in both cell lines. At low doses: 5x10(-8) and 5x10(-7) mol/l, this compound stimulates the enzyme by +73.5 and 52.7%, respectively, in MCF-7, and by 84.5 and 62.6% in T-47D cells. At high concentrations: 5x10(-6) and 5x10(-5) mol/l, medrogestone has no effect on MCF-7 cells, but inhibits the sulfotransferase activity in T-47D cells by -31.4% at 5x10(-5) mol/l. In conclusion, the inhibitory effect provoked by medrogestone on the enzyme involved in the biosynthesis of E2 (sulfatase pathway) in estrogen-dependent breast cancer, as well as the stimulatory effect on the formation of the inactive ES, support a probable anti-proliferative effect of this progestin in breast tissue. Clinical applications of these findings can open new therapeutic possibilities for this disease.