In the absence of hormone, the avian progesterone receptor exists in a large multiprotein complex that is inactive but able to bind and respond to progestins. This inactive complex can be reconstituted in vitro by incubation of receptor monomer in rabbit reticulocyte lysate in the presence of ATP and magnesium. This results in receptor binding to the two heat shock proteins, hsp90 and hsp70, th...

An immunocytochemical assay (ICA) for the measurement of estrogen receptor (ER) and progesterone receptor (PgR) has been evaluated in 426 human primary breast carcinomas. For estrogen receptor determination ER ICA was used. PgR ICA was performed using the monoclonal antibody KD 68. Assay results for progesterone receptor immunocytochemistry were in agreement (P less than 0.0001) with those of b...

Progesterone receptor and estrogen receptor participate in growth and differentiation of the different rat decidual regions. Steroid hormone receptor antagonists were used to study steroid regulation of decidualization. Here we describe a suppressive interaction between progesterone receptor (onapristone) and estrogen receptor (ICI182780) antagonists and their relation to a rescue phenomenon wi...

Little is known about the association between alcohol and breast cancer by different tumor characteristics. The study consisted of 184,418 postmenopausal women aged 50-71 years in the National Institutes of Health-AARP Diet and Health Study (1995-2003). Alcohol use, diet, and potential risk factors for cancer were assessed with a mailed questionnaire at baseline. The relative risks and 95% conf...

After administration of estradiol to castrated guinea pigs, a rise in the uterine concentration of specific progesterone binding sites (“receptor”) was observed as early as at 6 hours, and the peak of concentration (8-fold over basal values) was obtained within approximately 24 hours. The effect of the estrogen was prevented by RNA and protein synthesis inhibitors administered 15 min before est...

In addition to stimulation of the target gene fatty-acid synthetase, the synthetic progestin R5020 strongly inhibited estradiol-induced pS2 and cathepsin D mRNA levels in MCF7 human breast cancer cells as shown by Northern blot analysis. Inhibition was half-maximal with 30 pM R5020, and the antiprogestin RU486 had only a weak effect. Two human progesterone receptor isoforms have been described;...

Background: Breast cancer is one of the most common women’s cancers, and the number of cases is increasing worldwide. Objective: The current study compared invasive lobular carcinoma (ILC) and invasive ductal carcinoma with regard to the prevalence of estrogen receptor (ER), progesterone receptor (PR), and age prevalence. Methods: T...

Introduction: The interaction between steroid hormones and neurotransmitters such as GABA has been proved. The regulation of muscimol binding to high-affinity GABAA receptors by estradiol and progesterone has been studied within distinct brain regions using in vitro quantitative autoradiography. There are few studies about the mechanism of the effect of steroid hormones on behaviors such as ...

In pregnant rock hyraxes isolated leucocytes metabolise both [3H]pregnenolone and [3H]progesterone while whole blood, erythrocytes and an erythrocyte/leucocyte mixture only metabolised [3H]progesterone. Plasma displayed no tendency to metabolically convert any one of these two steroids. In whole blood [3H]progesterone appears to be converted to 5alpha-pregnane-3,20-dione and a compound with chr...

The existence of hormone receptors on or within neoplastic tissue has potential diagnostic, therapeutic, and prognostic importance. It was the purpose of this study to measure estrogen and progesterone receptors in a large group of patients with head and neck cancer to determine their frequency. Sixty-five patients with head and neck tumors underwent a total of 75 estrogen and 50 progesterone r...