16-alpha-ethyl-21-hydroxy-19-nor-4-pregnene-3-20-dione has been researched along with nomegestrol-acetate* in 2 studies
2 other study(ies) available for 16-alpha-ethyl-21-hydroxy-19-nor-4-pregnene-3-20-dione and nomegestrol-acetate
| Article | Year |
|---|---|
Inhibition by nomegestrol acetate and other synthetic progestins on proliferation and progesterone receptor content of T47-D human breast cancer cells.
Progesterone receptors (PgR) of human breast cancer T47-D cells grown in an estrogenic environment (presence of phenol red, natural estrogens of foetal calf serum and insulin) were found to be present in considerable amounts (1-3 pmol/mg protein and 20 pmol/mg DNA), and to specifically bind progestins with a high affinity characterized by a Kd around 3 nM for ORG2058, and 4 nM for nomegestrol acetate (NOM; 17 alpha-acetoxy-6-methyl-19-nor-pregna-4,6-diene-3, 20-dione), when measured under equilibrium conditions. Both compounds formed an highly stable ligand-receptor complex with a dissociation constant (k-1) around 1 x 10(-5) s-1. At high pharmacological concentrations, NOM, ORG2058 and other synthetic progestins including promegestone (R5020), medroxy-progesterone acetate and norethindrone acetate (NOR), induced a dose-dependent inhibition of cell proliferation as measured by [3H]thymidine incorporation. Dexamethasone, which did not bind to PgR, did not reproduce this inhibitory effect. NOM, R5020 and NOR treatments of T47-D cells at concentrations around Kd resulted in an 80% decrease in PgR content. Our data on NOM as compared to other progestins are consistent with their antiproliferative effects on human breast cancer cells grown in estrogenic conditions. Topics: Breast Neoplasms; Cell Division; Humans; Megestrol; Norpregnadienes; Pregnenediones; Progesterone Congeners; Promegestone; Receptors, Progesterone; Tumor Cells, Cultured | 1994 |
Kinetic analysis of the binding of nomegestrol acetate to the progesterone receptors in rat uterus by competition studies.
The characteristics of binding (Kinetic and equilibrium binding analysis) of nomegestrol acetate (NOM, 17 alpha-acetoxy-6 alpha-methyl-19-nor-pregna-4.6-diene-3.20-dione) to the progesterone receptor (PgR) in rat uterine cytosolic fraction were determined in comparison to progesterone (P), to fully appreciate the amplitude and specificity of the induced biological response. Since an appropriate radio-labelled form of this steroid molecule was not available, competition studies were performed against the synthetic progestin: [3H]-Organon 2058 [( 3H]-ORG). This allowed a direct comparison between the unlabelled forms of NOM and P, the kinetic constants of which were respectively: Inhibition constant (Ki): 22.8 and 34.3 nM; Association rate constant (k1): 0.39 X 10(3) and 0.21 X 10(3) M-1.s-1; Dissociation rate constant (k-1): 1.81 X 10(-5) and 2.16 X 10(-5) s-1. These results are much more informative than the mere determination of relative binding affinities which only reflect the specificity of the PgR. It was concluded that NOM behaves like the natural hormone in the cytosol of rat uterus. Topics: Animals; Binding, Competitive; Cytosol; Female; Kinetics; Megestrol; Norpregnadienes; Pregnenediones; Progesterone Congeners; Rats; Receptors, Progesterone; Uterus | 1990 |