PF-1092A

The possibility of therapeutic application of novel nonsteroidal progesterone receptor modulators CP8816 and CP8863 for preventing the development of uterine adenomyosis was investigated in mice. First priming effects of CP8816 on 17beta-estradiol (E2)-induced cell division in uterine tissues were examined. As a result, pretreatment with CP8816 or progesterone significantly suppressed the elevation of the mitotic activity in the luminal epithelial cells of mice treated with E2 later. Priming with CP8816 had little effect on the stromal cells, but progesterone priming caused an increase of stromal mitotic activity in mice treated with E2 later. To evaluate the inhibitory effect of these compounds on the development of adenomyosis induced experimentally by pituitary grafting, 7-week-old female mice were isografted with a single anterior pituitary in the uterus and divided into four groups. Two groups of mice were given daily subcutaneous injections of 1 mg of CP8816 or the vehicle alone for 6 weeks from the day after the grafting. Remaining two groups of mice were given oral administration of 1 mg of CP8863 or the vehicle only for 5 weeks starting one week after the grafting. The incidence of adenomyosis was significantly lower in the groups of mice treated with CP8816 and CP8863 than in the respective control groups. The mechanism by which CP compounds inhibited the development of adenomyosis might be related to their priming effects, i.e., their inhibitory effect on epithelial cell division and lack of effect on stromal cell division after subsequent exposure to E2.

The potential of new nonsteroidal progesterone receptor ligands, the derivatives of PF1092C ((4aR,5R,6R,7S)-6,7-dihydroxy-4a,5,6,7-tetrahydro-3,4a,5-trimethylnaphtho[2,3-b]furan-2(4H)-one) discovered from fungal metabolites, was evaluated. PF1092A ((4aR,5R,6R,7S)-6-acetoxy-7-hydroxy-4a,5,6,7-tetrahydro-3,4a,5-trimethylnaphtho[2,3-b]furan-2(4H)-one) showed good and moderate affinity for porcine and human progesterone receptors in in vitro receptor binding assays, respectively, and partial agonist activity for the progesterone receptor, as determined in assays of two types of progesterone-dependent enzymes in human mammary carcinoma T47D cells. The derivative of PF1092C, CP8481, ((4aR,5R,6R,7S)-6-(2-furancarbonyloxy)-7-hydroxy-4a,5,6,7-tetrahydro-3,4a,5-trimethylnaphtho[2,3-b]furan-2(4H)-one) possessed better affinity for both progesterone receptors and showed less cross-reactivity for other steroid receptors, such as rat androgen receptor, human glucocorticoid receptor, and human estrogen receptor, and was a more potent modulator of the progesterone receptor than PF1092A. CP8400 ((4aR,5R,6R,7S)-6,7-diacetoxy-4a,5,6,7-tetrahydro-3,4a,5-trimethylnaphtho[2,3-b]furan-2(4H)-one) and CP8401 ((4aR,5R,6R,7S)-6,7-dipropionyloxy-4a,5,6,7-tetrahydro-3,4a,5-trimethylnaphtho[2,3-b]furan-2(4H)-one), other derivatives, were indicated to be progesterone receptor antagonists. These results suggest that PF1092 compounds can serve as a new pharmacophore for potent and specific nonsteroidal progesterone receptor modulators.

The human progesterone receptor (PR) binding affinity and the PR agonistic or antagonistic potency of tetrahydronaphthofuranone derivatives were shown previously to be markedly influenced by substituents at the 6- and 7-positions. Here, we synthesized tetrahydrobenzindolones possessing a lactam ring, which enabled us to modify the 6- and 7-positions more freely, since tetrahydrobenzindolones are chemically more stable than tetrahydronaphthofuranones. The tetrahydrobenzindolone derivatives generally showed higher PR binding affinity than the corresponding tetrahydronaphthofuranones. We also succeeded in separating the agonistic and antagonistic activities by choosing suitable substituent groups at the 6- and/or 7-position(s) of the tetrahydrobenzindolone. The effects of representative agonists, 12c (CP8668), and 14a (CP8816), and a representative antagonist, 15f (CP8661), were confirmed in in vivo tests. In this report, we mainly describe the synthesis and structure-activity relationships (SAR) of tetrahydrobenzindolone derivatives, as new nonsteroidal PR ligands.