Synthesis of 16ß-derivatives of 3-(2-bromoethyl)-estra-1,3,5(10)-trien-17ß-ol as inhibitors of 17ß-HSD1 and/or steroid sulfatase for the treatment of estrogen-dependent diseases.

17ß-Hydroxysteroid dehydrogenase type 1 (17ß-HSD1) and steroid sulfatase (STS) are involved in the synthesis of the most potent estrogen in the human body, estradiol (E2). These enzymes are known to play a pivotal role in the progression of estrogen-dependent diseases, such as breast cancer and endometriosis. Therefore, the inhibition of 17ß-HSD1 and/or STS represents a promising avenue to modulate the growth of estrogen-dependent tumors or lesions. We recently established the key role of a bromoethyl side chain added at the C3-position of a 16ß-carbamoyl-benzyl-E2 nucleus to covalently inhibit 17ß-HSD1. To extend the structure-activity relationship study to the C16ß-position of this new selective irreversible inhibitor (PBRM), we synthesized a series of analog compounds by changing the nature of the C16ß-side chain but keeping the 2-bromoethyl group at position C3. We determined their 17ß-HSD1 inhibitions in T-47D cells (transformation of E1 into E2), but we did not obtain a stronger 17ß-HSD1 inhibitor than PBRM. Compounds 16 and 17 were found to be more likely to bind to the catalytic site and showed a promising but moderate inhibitory activity with estimated IC50 values of 0.5 and 0.7 µM, respectively (about 10 times higher than PBRM). Interestingly, adding one or two sulfamate groups in the D-ring's surroundings did not significantly decrease compounds' potential to inhibit 17ß-HSD1, but clearly improved their potential to inhibit STS. These results open the door to the development of a new family of steroid derivatives with dual (17ß-HSD1 and STS) inhibiting actions.

Chemical synthesis of C3-oxiranyl/oxiranylmethyl-estrane derivatives targeted by molecular modeling and tested as potential inhibitors of 17ß-hydroxysteroid dehydrogenase type 1.

17ß-Hydroxysteroid dehydrogenase type 1 (17ß-HSD1) is a promising therapeutic target known to play a pivotal role in the progression of estrogen-dependent diseases such as breast cancer, and endometriosis. This enzyme is responsible for the last step in the biosynthesis of the most potent estrogen, estradiol (E2) and its inhibition would prevent the growth of estrogen-sensitive tumors. Based on molecular modeling with docking experiments, we identified two promising C3-oxiranyl/oxiranylmethyl-estrane derivatives that would bind competitively and irreversibly in the catalytic site of 17ß-HSD1. They have been synthesized in a short and efficient route and their inhibitory activities over 17ß-HSD1 have been assessed by an enzymatic assay. Compound 15, with an oxiranylmethyl group at position C3, was more likely to bind the catalytic site and showed an interesting, but weak, inhibitory activity with an IC50 value of 1.3 µM (for the reduction of estrone into E2 in T-47D cells). Compound 11, with an oxiranyl at position C3, produced a lower inhibition rate, and the IC50 value cannot be determined. When tested in estrogen-sensitive T-47D cells, both compounds were also slightly estrogenic, although much less than the estrogenic hormone E2.