We have previously demonstrated that the steroid receptor antagonist mifepristone (RU486) causes growth inhibition of Chlamydophila pneumoniae by binding to and subsequently destroying the bacteria during their normal developmental cycle in epithelial HEp-2 cells. In the present study, we assessed the efficacy of treatment with RU486 against persistent C. pneumoniae infection in interferon (IFN...

The present study tested the hypothesis that ERK activation is an essential step in the onset of labor in a rat model of preterm labor. The administration of RU486, an antiprogesterone agent, to rats induced preterm delivery 22.2±0.24 hrs after treatment. Changes in basal signaling events were studied in myometrial tissue taken from CO2 euthanized rats. Rats treated with RU486 displayed a drama...

Progesterone (P4) promotes cell proliferation in several types of cancer, including brain tumors such as astrocytomas, the most common and aggressive primary intracerebral neoplasm in humans. In this work, we studied the effects of P4 and its intracellular receptor antagonist, RU486, on growth and infiltration of U373 cells derived from a human astrocytoma grade III, implanted in the motor cort...

Background: Progesterone is an endogenous immunomodulator that suppresses T cell activation during pregnancy. The stimulation of membrane progesterone receptors (mPRs) would seem to be the cause of rapid non-genomic responses in human peripheral T cells, such as an elevation of intracellular calcium ([Ca2+] i) and decreased intracellular pH (pHi). Mifepristoneimmune cells compared with progeste...

RU486 (mifepristone) has proved to be a remarkably active antiprogesterone and antiglucocorticosteroid agent in human beings. The mechanism of action involves the intracellular receptors of the antagonized hormones (progesterone and glucocorticosteroids). At the molecular level, the most important features are high binding affinity to the receptor, interaction of the phenylaminodimethyl group i...

BACKGROUND Progesterone is an endogenous immunomodulator that suppresses T cell activation during pregnancy. The stimulation of membrane progesterone receptors (mPRs) would seem to be the cause of rapid non-genomic responses in human peripheral T cells, such as an elevation of intracellular calcium ([Ca(2+)](i)) and decreased intracellular pH (pH(i)). Mifepristone (RU486) produces mixed agonist...

Polychlorinated biphenyls (PCBs) stimulate oxytocin secretion from bovine granulosa and luteal cells. Since oxytocin on the one hand is released from ovarian cells by cortisol and on the other hand PCBs can be bound by glucocorticoid receptors (GCr), we have tested the hypothesis that PCBs acting via GCr can stimulate oxytocin secretion. In preliminary studies the effect of RU486 (GCr blocker) ...

We have previously demonstrated a crosstalk between fibroblast growth factor 2 (FGF2) and progestins inducing experimental breast cancer growth. The aim of the present study was to compare the effects of FGF2 and of medroxyprogesterone acetate (MPA) on the mouse mammary glands and to investigate whether the antiprogestin RU486 was able to reverse the MPA- or FGF2-induced effects on both, mammar...

Limited proteolysis of in vitro produced human androgen receptor was used to probe the different conformations of the receptor after binding of androgens and several antiandrogens. The results provide evidence for five different conformations of the receptor, as detected by the formation of proteolysis resisting fragments: 1) an initial conformation of the unoccupied receptor not resisting prot...