Yasushi Kurata

CP8668, a novel orally active nonsteroidal progesterone receptor modulator with tetrahydrobenzindolone skeleton.

We investigated progestational activity of a new nonsteroidal compound, CP8668, ((4aR,5R,6R,7R)-7-methoxy-6-(N-propylaminocarbonyl)oxy-4a,5,6,7-tetrahydro-1,3,4a,5-tetramethylbenz[f]indol-2(4H)-one). CP8668 showed selective affinity for human progesterone receptor equal in strength to other steroidal progestins. CP8668 showed no significant affinity for human glucocorticoid receptor or human estrogen receptor and very weak affinity for rat androgen receptor. In endogenous and exogenous progesterone-dependent enzyme expression assays using human mammary carcinoma T47D, CP8668 showed mixed agonist-antagonist activity. However, in a rabbit endometrial transformation test, CP8668 showed good progestational activity following s.c. and p.o. administration. These results suggest that CP8668 is a selective and orally active progesterone receptor modulator, which shows mixed agonist-antagonist activity in in vitro transcription tests and agonist activity in endometrial transformation assays in rabbits, and that it is potentially a promising lead compound for a new type of orally active progesterone receptor modulator.

Fungal metabolites, PF1092 compounds and their derivatives, are nonsteroidal and selective progesterone receptor modulators

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.

Priming effects of novel nonsteroidal progesterone receptor modulators CP8816 and CP8863 on the development of adenomyosis in the mouse uterus

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.

In vitro and in vivo characterization of novel nonsteroidal progesterone receptor antagonists derived from the fungal metabolite PF1092C.

We studied the pharmacological effects of novel nonsteroidal progesterone receptor antagonists CP8661 and CP8754, which were synthesized from the fungal metabolite PF1092C. CP8661 possess a tetrahydrobenzindolone skeleton and CP8754 possess a tetrahydronaphthofuranone skeleton. In binding assays for steroid receptors, CP8661 and CP8754 inhibited [(3)H]-progesterone binding to human progesterone receptors (hPR), though they are less potent than RU486. CP8661 also showed moderate affinity to rat androgen receptors (rAR), although CP8754 did not. Neither compound showed affinity to human glucocorticoid receptors (hGR) or human estrogen receptors (hER). In exogeneous and endogeneous PR-dependent enzyme expression assays using human mammary carcinoma T47D, CP8661 and CP8754 showed pure antagonistic activity. In a rabbit endometrial transformation test, CP8661 and CP8754 showed anti-progestational activity by s.c. administration in a dose-dependent manner; meanwhile, these compounds showed no progestational activity at the same dose. These results suggested that CP8661 and CP8754 are in vivo effective pure progesterone receptor antagonists and presented the possibility of synthesizing pure progesterone receptor antagonists from both tetrahydronaphthofuranone and tetrahydrobenzindolone skeletons.