Effect of the antiprogestin RU-486 on progesterone inhibition of occupied nuclear estrogen receptor in the uterus

The ability of the antiprogestin, RU-486, to reverse progesterone (P) antagonism of occupied nuclear E receptor retention was studied in the rat and hamster uterus. RU-486 was shown to effectively displace [3H]P binding from rat uterine cytosolic P receptor in in vitro competition assay. In contrast, no competition by RU-486 for [3H]P binding was observed for uterine cytosolic P receptor from the hamster uterus. In the presence of sustained serum levels (silastic implants) of P and estradiol (E), occupied nuclear E receptor was significantly inhibited in the rat uterus. At 6, 12 and 24h after RU-486 treatment (5 mg/animal, s.c.) uterine receptors for E and P were determined. No significant differences in cytosolic E and P receptors were observed between treated (E + P, + RU-486) and control (E + P alone) animals. However, by 6 h following RU-486 treatment, occupied nuclear E receptor retention increased significantly (0.30 +/- 0.05 vs 0.60 +/- 0.09, pmol/uterus) and reached a peak between 12 h (1.32 +/- 0.09) and 24 h (0.83 +/- 0.09). The increase in nuclear E receptor approached the level observed in animals with an E implant alone (1.55 +/- 0.15). Measurement of uterine fluid accumulation following RU-486 treatment showed an increase which paralleled that observed for occupied nuclear E receptor retention. A similar in vivo experiment in the hamster showed no reversal of P inhibition of occupied nuclear E receptor. These results show that: 1. RU-486 is an effective competitor for rat uterine P receptor but not hamster P receptor; 2. RU-486 can rapidly reverse P inhibition of uterine occupied nuclear E receptor in the presence of sustained serum levels of E and P; 3. The recovery of occupied nuclear E receptor is coincident with a resumption of E action (uterine fluid accumulation). The studies also provide a novel means by which antiprogestin activity can be assessed in vivo in the presence of sustained E and P serum levels, e.g. the reversal of P inhibition of uterine nuclear E receptor retention.     

Regulation of BCRP/ABCG2 expression by progesterone and 17beta-estradiol in human placental BeWo cells

The breast cancer resistance protein (BCRP) is abundant in the placenta and protects the fetus by limiting placental drug penetration. We hypothesize that pregnancy-specific hormones regulate BCRP expression. Hence, we examined the effects of progesterone (P4) and 17beta-estradiol (E2) on BCRP expression in the human placental BeWo cells. P4 and E2 significantly increased and decreased BCRP protein and mRNA, respectively. Likewise, treatment with P4 and E2 increased and decreased, respectively, fumitremorgin C-inhibitable mitoxantrone efflux activity of BeWo cells. Reduction in BCRP expression by E2 was abrogated by the estrogen receptor (ER) antagonist ICI-182,780. However, the progesterone receptor (PR) antagonist RU-486 had no effect on P4-mediated induction of BCRP. P4 together with E2 further increased BCRP protein and mRNA compared with P4 treatment alone. This combined effect on BCRP expression was abolished by RU-486, ICI-182,780, or both. Further analysis revealed that E2 significantly decreased ER beta mRNA and strongly induced PR(B) mRNA in a dose-dependent manner but had no effect on PR(A) and ER alpha. P4 alone had no significant effect on mRNA of ER alpha, ER beta, PR(A), and PR(B). E2 in combination with P4 increased PR(B) mRNA, but the level of induction was significantly reduced compared with E2 treatment alone. Taken together, these results indicate that E2 by itself likely downregulates BCRP expression through an ER, possibly ER beta. P4 alone upregulates BCRP expression via a mechanism other than PR. P4 in combination with E2 further increases BCRP expression, presumably via a nonclassical PR- and/or E2-mediated synthesis of PR(B).     

RU-486 inhibits rat gonadal steroidogenesis

RU-486 is a synthetic steroid analogue that can inhibit adrenal steroid synthesis in the rat and rhesus monkey. We measured the activities of five testicular and two ovarian microsomal steroidogenic enzymes to assess the potential effect of RU-486 on rat gonadal steroidogenesis. Hypophysectomized, gonadotropin-replaced rats received RU-486 or a vehicle solution twice daily for seven days. The animals were sacrificed and their gonads were resected, weighed, and microsomal enzyme activities were measured according to RU-486 treatment. Testicular 17-hydroxylase and aromatase activity decreased in RU-486 treated animals whereas 17,20-desmolase, 3 beta-hydroxysteroid dehydrogenase and 17-ketosteroid reductase activities were unaffected. Ovarian 17-hydroxylase but not 3 beta-hydroxysteroid dehydrogenase activity was decreased in the animals receiving the drug. We conclude that RU-486 inhibits both testicular and ovarian steroidogenesis in the rat.     

Effect of neonatal treatment with mifepristone or tamoxifen on the binding capacity of the thymic glucocorticoid or uterine estrogen receptor of adult rats: data on the mechanism of hormonal imprinting

For studying the mechanism of perinatal hormonal imprinting newborn rats were treated with a single injection of the antihormones, mifepristone (RU486) or tamoxifen (100 microg each). Glucocorticoid receptors of thymi of 6 weeks old male and female, and uterine estrogen receptors of 2 months old female rats were studied for dexamethasone or estradiol binding, respectively. Tamoxifen caused faulty imprinting both in the thymic and uterine receptors, increasing affinity and density of males, and decreasing females' glucocorticoid receptors as well, as decreasing the density of uterine estradiol receptors. Neonatal mifepristone treatment was indifferent to the thymus, and decreasing to density of uterine estrogen receptors. Males' body weight significantly decreased 6 weeks after tamoxifen treatment. The results suggest that imprinting can not be provoked by a molecule (hormone antagonist) which can bind to the receptor without any postreceptorial events (mifepristone/glucocorticoid receptor), in the presence of some postreceptorial effects the reaction takes place, however the strongest reaction can be observed by the hormone analogue (tamoxifen) with postreceptorial (agonist) effect, not considering that the receptor is the direct target of the molecule or a cross-reaction is present.     

Comparison of the effects of estradiol-17beta and the synthetic estrogen, RU-2858, on lordosis behavior in adult female rats and guinea pigs

Female sexual behavior (as assessed by lordosis responses) in adult ovariectomized guinea pigs and rats was measured after a single subcutaneous injection of either the synthetic estrogen RU-2858 or estradiol-17β (E) and a subsequent injection of progesterone (P). Thresholds for responsiveness to each estrogen were determined over a range of doses from 1 to 640 μg/kg of body weight. RU-2858 was able to stimulate lordosis at doses several times lower than E in both guinea pigs and rats. In general, guinea pigs were less sensitive to both estrogenic compounds than rats and were particularly insensitive to E. Approximately 40% of guinea pigs given RU-2858 displayed lordosis prior to P injection. Subsequent P injection did not greatly enhance the intensity of lordosis responses in these animals. These guinea pigs were also more sensitive than the remaining 60% of RU-2858-injected guinea pigs on several indexes of lordosis intensity (e.g., lordosis threshold, duration of heat, duration of individual lordosis responses). Rats did not respond behaviorally to RU-2858 without a subsequent P injection nearly as frequently as did guinea pigs. At the doses used in this study, E did not facilitate lordosis behavior in rats or guinea pigs in the absence of a subsequent P injection.     

Role of ERK1/2 in uterine contractility and preterm labor in rats

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 RU-486, an antiprogesterone agent, to rats induced preterm delivery 22.2 +/- 0.24 h after treatment. Changes in basal signaling events were studied in myometrial tissue from CO(2)-euthanized rats. Rats treated with RU-486 displayed a dramatically increased in vitro uterine contractility compared with gestational stage-matched, sham-treated rats. In vitro contractility was not significantly different from that during spontaneous labor. During RU-486-induced preterm labor, as previously described for spontaneous labor, ERK phosphorylation levels increased, as did phosphorylation of caldesmon at Ser(789), an ERK phosphorylation site. Also, a small but significant increase in 20-kDa myosin light chain phosphorylation was seen at a constant intracellular pCa of 7. When rats were chronically treated with an agent that prevents ERK activation, U-0126, the onset of RU-486-induced preterm labor was delayed in a statistically significant manner. Chronic in vivo treatment with U-0126 also significantly inhibited the RU-486-induced increase in in vitro contractility and ERK and caldesmon phosphorylation but did not alter the RU-486-induced increase in 20-kDa myosin light chain phosphorylation. These data indicate that ERK activation is a component of the multiple events leading to the development of labor in this rat model. We suggest that the ERK pathway could possibly be used to identify targets for the development of a novel class of tocolytic agents.     

Partial inhibition of estrogen-induced mammary carcinogenesis in rats by tamoxifen: balance between oxidant stress and estrogen responsiveness

Epidemiological and experimental evidences strongly support the role of estrogens in breast tumor development. Both estrogen receptor (ER)-dependent and ER-independent mechanisms are implicated in estrogen-induced breast carcinogenesis. Tamoxifen, a selective estrogen receptor modulator is widely used as chemoprotectant in human breast cancer. It binds to ERs and interferes with normal binding of estrogen to ERs. In the present study, we examined the effect of long-term tamoxifen treatment in the prevention of estrogen-induced breast cancer. Female ACI rats were treated with 17β-estradiol (E2), tamoxifen or with a combination of E2 and tamoxifen for eight months. Tissue levels of oxidative stress markers 8-iso-Prostane F(2α) (8-isoPGF(2α)), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase, and oxidative DNA damage marker 8-hydroxydeoxyguanosine (8-OHdG) were quantified in the mammary tissues of all the treatment groups and compared with age-matched controls. Levels of tamoxifen metabolizing enzymes cytochrome P450s as well as estrogen responsive genes were also quantified. At necropsy, breast tumors were detected in 44% of rats co-treated with tamoxifen+E2. No tumors were detected in the sham or tamoxifen only treatment groups whereas in the E2 only treatment group, the tumor incidence was 82%. Co-treatment with tamoxifen decreased GPx and catalase levels; did not completely inhibit E2-mediated oxidative DNA damage and estrogen-responsive genes monoamine oxygenase B1 (MaoB1) and cell death inducing DFF45 like effector C (Cidec) but differentially affected the levels of tamoxifen metabolizing enzymes. In summary, our studies suggest that although tamoxifen treatment inhibits estrogen-induced breast tumor development and increases the latency of tumor development, it does not completely abrogate breast tumor development in a rat model of estrogen-induced breast cancer. The inability of tamoxifen to completely inhibit E2-induced breast carcinogenesis may be because of increased estrogen-mediated oxidant burden.     

Effect of ovarian steroids on nitric oxide synthase in the rat uterus, cervix and vagina

The effects of estrogen (E2), progesterone (P) and E2 and P (E2 + P) were examined on nitric oxide synthase (NOS) activity in both cytosolic and particulate fractions isolated from the rat uterus, vagina, cervix and cerebral cortex. Additionally plasma nitrate + nitrite (NO3 + NO2) levels were measured in control and hormone treated rats. Cytosolic NOS was the predominant form being approximately 80% of the total in all four tissues. NOS activity in both fractions from all tissues was highly Ca-dependent (> 90%). Among the reproductive tract tissues, the highest activity was found in the cervix, which was nearly 5- and 2-fold higher than the uterus and vagina, respectively. NOS activity in the cerebral cortex was by far the highest being 5-fold higher than in the cervix. In contrast to the cortex, E2 treatment downregulated cytosolic NOS in all reproductive tract tissue, but this was statistically significant in only uterus. When compared with E2 treated rats, P increased cytosolic NOS in uterus, vagina, and particulate NOS in the cervix. The data do not give any indication whatsoever of differential effects of P in the uterus and cervix.     

Testosterone inhibits estrogen-induced mammary epithelial proliferation and suppresses estrogen receptor expression.

This study investigated the effect of sex steroids and tamoxifen on primate mammary epithelial proliferation and steroid receptor gene expression. Ovariectomized rhesus monkeys were treated with placebo, 17beta estradiol (E2) alone or in combination with progesterone (E2/P) or testosterone (E2/T), or tamoxifen for 3 days. E2 alone increased mammary epithelial proliferation by approximately sixfold (P:<0.0001) and increased mammary epithelial estrogen receptor (ERalpha) mRNA expression by approximately 50% (P:<0.0001; ERbeta mRNA was not detected in the primate mammary gland). Progesterone did not alter E2's proliferative effects, but testosterone reduced E2-induced proliferation by approximately 40% (P:<0.002) and entirely abolished E2-induced augmentation of ERalpha expression. Tamoxifen had a significant agonist effect in the ovariectomized monkey, producing a approximately threefold increase in mammary epithelial proliferation (P:<0.01), but tamoxifen also reduced ERalpha expression below placebo level. Androgen receptor (AR) mRNA was detected in mammary epithelium by in situ hybridization. AR mRNA levels were not altered by E2 alone but were significantly reduced by E2/T and tamoxifen treatment. Because combined E2/T and tamoxifen had similar effects on mammary epithelium, we investigated the regulation of known sex steroid-responsive mRNAs in the primate mammary epithelium. E2 alone had no effect on apolipoprotein D (ApoD) or IGF binding protein 5 (IGFBP5) expression, but E2/T and tamoxifen treatment groups both demonstrated identical alterations in these mRNAs (ApoD was decreased and IGFBP5 was increased). These observations showing androgen-induced down-regulation of mammary epithelial proliferation and ER expression suggest that combined estrogen/androgen hormone replacement therapy might reduce the risk of breast cancer associated with estrogen replacement. In addition, these novel findings on tamoxifen's androgen-like effects on primate mammary epithelial sex steroid receptor expression suggest that tamoxifen's protective action on mammary gland may involve androgenic effects.     

Comparative study of the short-term effects of a novel selective estrogen receptor modulator, ospemifene, and raloxifene and tamoxifen on rat uterus

To investigate the differential short-term effects of selective estrogen receptor (ER) modulators (SERMs) on uterus, we treated adult ovariectomized rats with a novel SERM, ospemifene (Osp), two previously established SERMs (tamoxifen and raloxifene (Ral)) and estradiol. The expression of two estrogen-regulated early response genes c-fos and vascular endothelial growth factor (VEGF), and DNA synthesis were analysed at 1-24 h after treatment of ovariectomized rats. Induction of c-fos mRNA by each of the SERMs showed a biphasic pattern with peaks at 3 and 20 h, respectively. The maximum level of VEGF mRNA was observed at 1 h after raloxifene and 6 h after tamoxifen or ospemifene treatment. Maximum levels of the c-fos and VEGF mRNA after raloxifene treatment were higher than those seen after treatments with E2 or a corresponding dose of tamoxifen or ospemifene. DNA synthesis was significantly increased by ospemifene, tamoxifen and raloxifene both in luminal and glandular epithelium. The stimulation was transient, peaking at 16 h. In comparison, the maximum level observed at 16 h after E2 treatment sustained at least until 24 h. DNA synthesis in stromal cells was increased by the SERMs but not by E2 at 24 h. When treated together with E2, the SERMs were able to antagonise E2-stimulated DNA synthesis at 16 h. Our results demonstrate that the initial response of uterus to ospemifene, raloxifene and tamoxifen includes activation of early response genes and even transient stimulation of DNA synthesis in spite of their different long-term effects. However, the early stimulatory events may be mediated by different mechanisms leading to diverging pathways in various tissue compartments and development of differential SERM-specific long-term responses of uterus.     

Progesterone regulation of epidermal growth factor receptor in rat decidua basalis during pregnancy.

Ovarian steroid hormones and epidermal growth factor (EGF) play important interactive roles in proliferation and decidualization of mesometrial stromal cells during pregnancy. This study determined the ontogeny of EGF receptor (EGF-R) expression in the decidua basalis (DB) throughout pregnancy and its regulation by estrogen and progesterone (P4). DB were isolated from rats between Days 8-21 of pregnancy and prepared for immunohistochemistry or Western analysis. In one study, rats were ovariectomized (Ovx) on Day 8 or 9 and given estradiol-17beta, P4, or both. In another study, the antiprogestin, mifepristone (RU-486), was administered on Day 9. During normal pregnancy, total EGF-R (phosphorylated and unphosphorylated forms) increased from Day 8 to a maximum level on Days 10 and 12. Tyrosine-phosphorylated EGF-R (pEGF-R), the bioactive form, was also highest on Days 10 and 12. Both forms of receptor decreased to almost undetectable levels during DB regression on Days 17-21. Immunohistochemistry of DB from Ovx rats revealed that only P4 was able to maintain normal expression of EGF-R; RU-486 decreased EGF-R expression within 6 h, and by 24 h EGF-R and pEGF-R were 15% of the Day 10 control group levels. These findings show that EGF-R is a P4-dependent protein associated with stromal cell proliferation and decidualization.     

Effects of adrenal hormones on the expression of adiponectin and adiponectin receptors in adipose tissue, muscle and liver

Background

Adiponectin, an insulin-sensitive hormone that is primarily synthesized in adipose tissue, exerts its effects by binding to two receptors, adipoR1 and adipoR2. Little is known regarding the effects of glucocorticoids on the expression of adiponectin receptors.

Methods

Male Wistar rats were bilaterally adrenalectomized and treated with dexamethasone (0.2 mg/100 g) twice daily for 3 days. To analyze the potential effects of glucocorticoids, rats received two daily injections of the glucocorticoid receptor antagonist (RU-486, 5.0 mg) over the course of 3 days. Additionally, 3T3-L1 adipocytes and C2C12 myotubes were treated with dexamethasone, adrenaline or RU-486. The gene expression of adiponectin, adipoR1 and adipoR2 was determined by real-time PCR, and protein secretion was examined by Western blotting using lysates from retroperitoneal, epididymal and subcutaneous adipose tissue depots, liver and muscle.

Results

In rats, excess glucocorticoids increased the levels of insulin in serum and decreased serum adiponectin concentrations, whereas adrenalectomy decreased the mRNA expression of adiponectin (3-fold) and adipoR2 (7-fold) in epididymal adipose tissue and increased adipoR2 gene expression in muscle (3-fold) compared to control group sham-operated. Dexamethasone treatment did not reverse the effects of adrenalectomy, and glucocorticoid receptor blockade did not reproduce the effects of adrenalectomy. In 3T3-L1 adipocytes, dexamethasone and adrenaline both increased adipoR2 mRNA levels, but RU-486 reduced adipoR2 gene expression in vitro.

Conclusion

Dexamethasone treatment induces a state of insulin resistance but does not affect adiponectin receptor expression in adipose tissue. However, the effects of catecholamines on insulin resistance may be due to their effects on adipoR2.     

Estrogen- and Antiestrogen-responsiveness of HEC1A Endometrial Adenocarcinoma Cells in Culture

HEC1A endometrial cancer cells express the wild-type form of the estrogen receptor (ER) and 17β-estradiol (E2) induces proliferation of these cells. In contrast, tamoxifen only causes a minimal increase (<20%) in cell proliferation. In HEC1A cells transiently transfected with the C3-Luc plasmid derived from the complement C3 gene, both E2 and tamoxifen exhibited ER agonist activity and tamoxifen was also a partial antagonist for this response. The relative ER agonist/antagonist activities of E2, tamoxifen and ICI 182,780 were also investigated in HEC1A1 cells transiently transfected with two E2-responsive plasmids, pCATHD-CAT and pCKB-CAT which contain 5′-promoter inserts from the cathepsin D and creatine kinase B genes, respectively. The results showed that E2 and tamoxifen induced reporter gene activity in cells transiently transfected with both constructs. ICI 182,780 exhibited partial ER agonist activity only in cells transiently transfected with pCKB-CAT and antagonized E2-induced reporter gene activity using both the CKB- and CATHD-derived constructs. These results demonstrate that HEC1A endometrial cancer cells are E2-responsive and represent a useful cell culture model for understanding hormone/antihormone-induced endometrial cell responses.     

Antiandrogenic and apoptotic effects of RU-486 on animal prostate

Mifepristone (RU-486) is a potent antagonist of steroid hormone receptors such as glucocoticoid and progesterone receptors. This compound also is a very strong inducer of the interaction between androgen receptors and corepressors NCoR and SMRT and therefore could be used as selective receptor modulator.

In this study we determined the relative binding affinity of RU-486 to androgen receptors (AR) obtained from rat prostate cytosol as well as the in vivo effect of different doses of RU-486 on the prostate weight of hamsters treated with dihydrotestosterone and/or RU-486. We determined also the prostate cell death (apoptosis) in hamster treated with, dihydrotestosterone (DHT) and/or RU-486.

The results of this study indicated that the relative binding affinity of RU-486 for AR is 4.3%. The data from the in vivo experiments also showed that RU-486 inhibited the prostate weight significantly in the highest doses thus indicating the antagonistic action of this compound on hamster prostate.

The immunohistochemistry analysis showed that after 1 month of castration, the hamster prostate was atrophic. Treatment with DHT produced epithelial cell activity (measured by the increase in the prostate weight) and very low rate of apoptosis. When DHT was administered together with RU-486 (10 mg/kg) no change was observed. On the other hand, DHT plus higher doses of RU-486 (40, 80 mg/kg) resulted in an increase of apoptosis in stromal and secretory epithelial cells. In addition to the increase of the prostate cell apoptosis produced by the treatment with high dose of RU-486, other factors could contribute to the decrease of the prostate weight observed. Another possibility could be a reduction in the ductal fluid due to poor epithelial cell secretory activity more than apoptosis itself. Furthermore, in this experiment, RU-486 could have inhibited the growth of the prostate gland produced by DHT in a greater extent than the induction of atrophy and cell death. This fact could depend on the doses used, due to the low affinity of this compound for the androgen receptors.     

Mechanism of the stimulatory action of antisteroid RU486 on follicle-stimulating hormone secretion in the cyclic Rat

These experiments explored the mechanism underlying FSH hypersecretion on estrous afternoon in rats injected with RU486 (RU) on proestrus. Four-day cyclic rats were injected with RU at 12:00 h on proestrus (1 or 4 mg/0.2 ml oil; s.c.), and its effects on LH and FSH secretion at 18:30 h on estrus were compared with those of antiprogestagens ZK299 (ZK) (1 or 4 mg/0.2 ml oil; s.c.) and Org31806 (OR) (2 or 8 mg/0.2 ml oil; s.c.). Additionally, rats treated with RU or nembutal (PB) (60 mg/kg; i.p. at 13:00 h on proestrus) were injected with an LHRH antagonist (LHRHa) at 10:00 h on estrus (1 mg/0.2 ml saline; s.c.) or progesterone (P) (7.7, 15.5 or 30.9 mg/0.2 ml oil; s.c.) on proestrus at 10:00 h in RU-injected rats and at 14:00 h in PB-injected rats. Animals were killed by decapitation at 18:30 h on estrus and serum LH and FSH concentrations were determined. Rats treated with 1 or 4 mg of RU or Org or 4 mg of ZK recorded increased serum FSH on estrous afternoon, while 1 mg ZK had no effect. PB increased mainly serum LH levels and, to a lesser extent, FSH levels. P decreased serum FSH concentrations in both RU- and PB-injected rats. LHRHa reversed the effects of PB on FSH secretions, but reduced FSH hypersecretion induced by RU only. These results are interpreted to mean that, in the absence of proestrous afternoon P-inhibitory action of the neural stimulus controlling LHRH release, FSH secretion on estrous afternoon involves two components: one is LHRH dependent while, in contrast to LH secretion, the other is LHRH independent, and only expressed in a low estrogen background.     

Glucocorticoids and TNFalpha interact cooperatively to mediate sepsis-induced leucine resistance in skeletal muscle

Sepsis blunts the ability of nutrient signaling by leucine to stimulate skeletal muscle protein synthesis by impairing translation initiation. The present study tested the hypothesis that overproduction of either tumor necrosis factor (TNF)-alpha or glucocorticoids mediate the sepsis-induced leucine resistance. Prior to producing peritonitis, rats received either vehicle, TNF binding protein (TNF(BP)) to inhibit endogenous TNFalpha action, and/or the glucocorticoid receptor antagonist RU486. Leucine was orally administered to all rats 24 h thereafter and the gastrocnemius removed 20 min later to assess protein synthesis and signaling components important in controlling peptide-chain initiation. Muscle protein synthesis was 65% lower in septic rats administered leucine than in leucine-treated control animals. This reduction was not prevented by either TNF(BP) or RU486 alone, but was completely reversed by the combination. This sepsis-induced leucine resistance was associated with an 80% reduction in the amount of active eIF4E.eIF4G complex, a 5-fold increase in the formation of the inactive eIF4E.4E-BP1 complex as well as markedly reduced (at least 70%) phosphorylation of 4E-BP1, eIF4G, S6K1, S6, and mTOR. Pretreatment of septic rats with either TNF(BP) or RU486 individually only nominally improved the leucine action as assessed by the above-mentioned endpoints. In contrast, when TNF(BP) and RU486 were co-administered, the ability of sepsis to impair the leucine-stimulated phosphorylation of 4E-BP1, eIF4G, S6K1, and S6 as well as the redistribution of eIF4E was essentially prevented. No differences in the total amount or phosphorylation of eIF2alpha and eIF2Bepsilon were detected between the different groups, and changes could not be attributed to differences in the prevailing plasma concentration of insulin or leucine. Our data demonstrate the sepsis-induced leucine resistance in skeletal muscle results from the cooperative interaction of both TNFalpha and glucocorticoids.     

RU 486: how abortion politics have impacted on a potentially useful drug of broad medical application.

RU-486 or mifepristone is best known as an antiprogestin and an abortifacient, but it has broad medical applicability. The drug is also a potent blocker of corticosteroid receptors, and it has shown promise in the treatment of breast cancer, inoperable meningioma, and cushing's disease. Cushing's is a model for the symptomatology of aging which may involve enhanced response to corticosteroid. RU-486 has reversed the osteoporosis, thinning of skin, muscle atrophy, obesity, adult onset diabetes, depression, hypertension, and immunosuppression associated with this disease. RU-486 may be of value in aiding cervical dilation, lactation, and the treatment of endometriosis. In addition, breast, bowel, kidney tumors, hepatomas, endometrial cancer, and fibrosarcomas can show corticosteroid dependency, suggesting that RU-486 may have clinical value against inoperable tumors. In a preliminary 1987 phase I study, in estrogen-positive, chemotherapy-refractory breast cancer patients in Montpelier, France, Ru-486 produced objective tumor regression (6 of 22) that was prolonged (3 months) in 4 patients. Clinical relief of bone pain was observed in 7 of 23 patients with a decline in carcinoembryonic antigen (CEA) tumor makers in 8 patients. Growing in vitro data also show that RU-486 can directly inhibit breast cancer cell proliferation. RU-486 has application for HIV infection, based on data that there is a serum factor in AIDS patients that enhances corticosteroid lympholysis. IN addition, the immune restorative action of RU-486 suggests that it could counteract the immunosuppression seen in aging, in cancer, or in viral or stress-related disease, which has recently focused clinical attention on its potential in the treatment of senile dementia and depression. Scientific conferences and workshops are needed to alert scientists, physicians, and the public to the potential medical benefits of this drug.