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J P Raynaud

Publications and source records attributed to J P Raynaud.

At least 55 records · Page 3Linked to original sources
PubMed1988

11 beta-substituted steroids, an original pathway to antihormones.

11 beta-substituted steroids form a novel class of derivative for the study of ligand-receptor interactions. The present review describes the synthetic pathways leading to 11 beta-substituted norsteroids and the kinetics and specificity of their interaction with receptors of several hormone classes as determined in a routine screening programme. The biochemical data on the interaction of one of these compounds, RU 38486, a potent antihormone presently in clinical development, with the progestin (PR) and glucocorticoid (GR) receptors are briefly reviewed. The comparison of the 3D-structures of these antagonists with those of potent hormones can help to map the interaction sites with PR and GR and highlights the potential use of these molecules as labelling agents and molecular probes.

Animals↗
PubMed1988

Binding of steroids to the progestin and glucocorticoid receptors analyzed by correspondence analysis.

The relative binding affinities of over 30 steroids have been measured for the cytosol glucocorticoid receptor (GR) of thymus, liver, and hepatoma tissue culture cells and for progestin, androgen, and mineralocorticoid receptors. The data have been analyzed by correspondence analysis to reveal the singularities among the receptors of different hormonal classes, the similarities in GR of different origins, and the different specificities of the ligands. Additional data on new steroids have been injected into the system as well as results on a further parameter, namely the induction of tyrosine aminotransferase (TAT) activity, to illustrate the power and flexibility of the methodology. The analysis has confirmed previous correlations between GR binding and TAT response but also highlighted the antiglucocorticoid activity of progestins. This method should prove to be a substantial aid to the interpretation of increasingly complex data, in particular with regard to the action of existing and newly synthesized steroids on glucocorticoid systems of differential sensitivity.

Animals↗
PubMed1988

Antiandrogens in combination with LH-RH agonists in prostate cancer.

The rationale of the combination of a nonsteroid antiandrogen with an LH-RH analogue (LH-RH-A) in the treatment of prostate cancer is discussed. Whereas the LH-RH-A depresses testosterone (T) levels via an action on the hypothalamus-pituitary-gonad axis, the antiandrogen counters the effect of any residual T, from the testes or adrenals, on the target organ, the prostate. Although bilateral orchiectomy and administration of estrogen or LH-RH-A give equivalent low T levels over long-term treatment, the manner and rate at which T suppression is achieved vary and each treatment presents characteristic disadvantages. Orchiectomy is irreversible, and it is known that approximately 20% of patients will not benefit from such endocrine manipulation, estrogen use is associated with cardiovascular disease, and LH-RH analogues produce an early surge in T. None of these treatments has any significant effect on adrenal androgen levels, which may contribute toward the progression of disease. Nonsteroid antiandrogens such as anandron and flutamide inhibit the uptake of androgen by the prostate by an action that probably involves the androgen receptor. They do not possess the progestational and glucocorticoid component of steroid antiandrogens or their pituitary inhibitory activity but do exert some inhibition of the 17 alpha-hydroxylase and 17,20-lyase enzyme systems. Unlike steroids, the nonsteroid antiandrogens potentiate the activity of LH-RH-A at the central level in the rat. The inhibitory action of the combined treatment of "anandron + buserelin" on the prostate is greater than that of each compound alone. Clinical pharmacology studies have demonstrated that both steroid and nonsteroid antiandrogens can help to control the effect of increased T levels (disease flare) that occur on initiating LH-RH-A administration. Prostatic acid phosphatase (PAP) levels decrease immediately in spite of the increase in T. The decrease appears faster when nonsteroid antiandrogens are used. Nonsteroid antiandrogens sensitize the pituitary to stimulation by LH-RH in eugonadal volunteers. The results of randomized clinical studies with the combination of "nonsteroid antiandrogen + LH-RH-A" have established a definite trend toward greater efficacy of the combined treatment over monotherapy. Further data are needed to confirm this trend. In particular, further dose-ranging studies are warranted since the need for LH-RH-A doses that reduce T down to castration levels may not be justified in the presence of a potent antiandrogen.(ABSTRACT TRUNCATED AT 400 WORDS)

Androgen Antagonists↗
PubMed1988

(De)phosphorylation agents influence 5 alpha-reduction of testosterone in human prostate.

The effects of ATP and of 2,4-dinitrophenol (DNP) on the kinetics of 5 alpha-reductase were studied in a microsomal preparation from hyperplastic human prostates. DNP decreased and ATP increased enzyme activity in a dose-dependent manner. Furthermore, in one and the same prostate, activity was inversely correlated to prostatic acid phosphatase (PAP) concentration. These observations provide strong support for the contention that in the human prostate 5 alpha-reductase activity and, consequently, dihydrotestosterone (DHT) production may be energy dependent and involve a phosphorylation step.

2,4-Dinitrophenol↗
PubMed1987

Towards the mapping of the progesterone and androgen receptors.

At a time when the secondary structures of receptor proteins are being predicted from sequence data by modeling techniques, knowledge of the ligand characteristics compatible with high-affinity binding to the receptor and with efficient receptor function is indispensable. We have already compared progesterone receptor (PR) ligands in attempts to map the PR hormone-binding site. In the present study, the relative binding affinities (RBAs) of 33 steroid ligands for the cytosol androgen receptor (AR) of rat prostate, measured in a routine screening system, have been compared. Special emphasis has been given to the effects of modifications (unsaturation, methylation, substitution by halogens) that might influence AR recognition by the ring A carbonyl and also to the consequences of these changes on binding specificity. Nonsteroid antiandrogens are reputed to compete with labelled testosterone (or methyltrienolone) binding to AR. Their RBAs, however, are very low compared to those of steroid antiandrogens. It is feasible that such molecules might occupy and interact with the AR site that binds hormone. The solvent accessible surface of one Anandron conformer is highly similar to that of testosterone and this conformer can be adequately superimposed upon the structure of testosterone and of antiandrogenic Des-A steroid derivatives. The nitro group might assume the role of the ring A carbonyl of steroids; reduction of this group to an amine or a hydroxylamine completely suppresses binding. These observations, however, do not eliminate the hypothesis of interference with AR function, and consequent antiandrogenic activity, by interaction with other (adjacent) sites on AR.

Androgen Antagonists↗
PubMed1987

Design of antiandrogens and their mechanisms of action: a case study (anandron).

The design of a new drug is conditioned by knowledge of the biochemical mechanisms involved in the etiology of the disease to be treated. With regard to endocrine pathologies, such knowledge can be obtained in the clinic from systematic assays of urinary and plasma hormones, enzyme activities and target tissue receptor concentrations. The present paper describes the results of our assays of plasma 3 alpha-androstanediol glucuronide, 5 alpha-reductase and androgen receptor in prostate cancer patients. The activity of the nonsteroid antiandrogen anandron is discussed in relation to these parameters: anandron may inhibit slightly adrenal androgen biosynthesis but, in particular, counters the action of these adrenal androgens on the prostate. It does not inhibit rat prostate 5 alpha-reductase activity but interacts with androgen receptor to exert an antiandrogen action.

Androgen Antagonists↗
PubMed1986

Pharmacology of an antiandrogen, anandron, used as an adjuvant therapy in the treatment of prostate cancer.

To improve the inhibition of prostate cancer growth obtained by surgical or chemical castration (estrogens or LHRH analogs), blockade of the action of residual androgens of adrenal origin has been proposed. Among antiandrogens acting through the androgen receptor (AR), the nonsteroid anandron (RU 23908) has several advantages over available compounds: megestrol acetate and cyproterone acetate, both steroids, bind substantially to other hormone receptors (progestin, gluco- and mineralocorticoid); and anandron binds only to AR. The nonsteroid flutamide is a prodrug converted to the active metabolite, hydroxyflutamide; anandron is well absorbed on oral administration of an active dose and intact compound disappears slowly from plasma. This may explain why, although in vitro anandron interacts very transiently with AR, in vivo a high level of untransformed anandron is present at the receptor site to induce its antiandrogenic activity. Animal experiments confirm that anandron can counteract the effect of adrenal androgens and inhibit the LHRH analog-induced initial increase in androgen ("flare-up"). Thus, in rats castrated either surgically or by buserelin or DES and supplemented with adrenal androgens (since endogenous adrenal secretion is very low in this species compared to man), anandron decreased prostate weight to control levels. The administration of buserelin to intact rats over 15 days resulted in a significant increase in prostate weight between Days 1 and 5. The addition of anandron to the buserelin inhibited this increase and, furthermore, led to a far greater decrease in prostate weight than that due to buserelin alone at 15 days, indicating a synergy of action.

Androgen Antagonists↗
PubMed1986

Correspondence analysis applied to steroid receptor binding.

The relative binding affinities of 48 steroids for four classes of hormone receptor (progestin, PR; androgen, AR; glucocorticoid, GR; mineralocorticoid, MR) have been analyzed by correspondence analysis. The steroids were, for the most part, derivatives of nortestosterone, differing by their degree of unsaturation, by the presence or absence of a 17 alpha-ethynyl group, and by the length of the C-13 alkyl substituent. Derivatives of norprogesterone were included as reference compounds. Distribution maps visualizing the results of the mathematical analysis revealed that the majority of the test steroids were within the zone of influence of AR and PR and had limited affinity for GR and MR. Overall lack of specificity and enhanced affinity for GR and MR were induced by increasing unsaturation and by the presence of a C-13 ethyl group. The general and specific conclusions of the analysis confirm and extend previous intuitive and partial interpretations of the data. Correspondence analysis, however, has the advantage of taking into account the sum total of the available information, without any preconceived notion of the relative importance of a specific structural feature or biological parameter and, furthermore, enables simultaneous representation on a single graph of the receptor and steroid fields. The present example demonstrates the use of this type of methodology in processing routine screening data involving multiple parameters.

Chemical Phenomena↗
PubMed1986

Interactions of oestradiol benzoate and promegestone upon basal and TRH-induced prolactin secretion in postmenopausal women.

The interactions of ovarian steroids with PRL secretion in women are still controversial. Ten healthy postmenopausal women, on no medication, received during the first period of 2 months later in a cross-over design study, i.m. injections of 0.625 mg of oestradiol benzoate (EB) alone for 10 d or in combination with 750 micrograms/d of a pure progestin promegestone for 10 d. A TRH (200 micrograms i.v.) stimulation test was performed before the start and at the completion of each treatment period. Basal plasma gonadotrophins, PRL and oestradiol were measured every day by radioimmunoassay. The EB-induced rise in oestradiol levels was similar during the two periods. In response to EB treatment serum PRL levels increased from 6.1 +/- 0.9 ng/ml to 22.9 +/- 3.4 ng/ml. With the addition of promegestone, the increase in PRL, from 6.7 +/- 1.3 ng/ml to 13.8 +/- 2.5 ng/ml, was significantly diminished (P less than 0.001). The PRL release induced by TRH was significantly greater with EB treatment than was the response with the combined treatment (P less than 0.05, Wilcoxon test to compare the areas under the curves). These data suggest that in postmenopausal women oestrogens act as stimulators of PRL release and promegestone is able to partially counteract the stimulatory effect of oestradiol benzoate upon basal and TRH-stimulated PRL secretion.

Drug Interactions↗
PubMed1986

[Cancer of the prostate: biologic bases for the use of an antiandrogen in its treatment].

Although orchiectomy, estrogens and LHRH agonists suppress testicular androgens, they are without effect on adrenal androgens which are converted into dihydrotestosterone in the prostate. It is therefore necessary to develop substances able to block the action of all androgens, whatever their source, on target organs. The non-steroid, Anandron (RU 23908), when administered orally, gives rise to a high and sustained plasma level of intact compound that inhibits testosterone binding to its receptor. This inhibition, however, occurs not only in the prostate but also in the pituitary. The negative feedback action of androgens is thus inhibited by Anandron resulting in an increased secretion of testosterone and explaining the necessity of combining Anandron with castration (whether surgical or medical by an LHRH agonist). Anandron opposes, on the one hand, the action of adrenal androgens and, on the one other, of the testosterone surge that occurs during the early days of treatment with the LHRH analog. The efficacy of the combined treatment has been demonstrated experimentally. Clinical trials are presently underway.

Androgens↗
PubMed1984

The pure antiandrogen RU 23908 (Anandron), a candidate of choice for the combined antihormonal treatment of prostatic cancer: a review.

The nonsteroidal antiandrogen RU 23908 ( Anandron ) weakly interacts with the prostatic cytosolic androgen receptor and shows a fast dissociation rate. When administered to immature castrated rats up to the daily dose of 100 mg/kg, it is devoid of any androgenic activity but efficiently blocks the growth-promoting activity of androgens on ventral prostate and seminal vesicle weight, thus showing the characteristics of a pure antiandrogen. In intact animals, on the other hand, the antiandrogen administered alone exerts only a partial inhibition of prostate and seminal vesicle weight. This is due to the property of the pure antiandrogen to neutralize the inhibitory feedback effect of androgens at the pituitary level on the LH responsiveness to LHRH, as illustrated in vitro in rat anterior pituitary cells in culture as well as in vivo in intact and castrated animals. In intact animals, neutralization of the inhibitory feedback action of endogenous androgens leads to an increased LH and testosterone secretion, which partly overcomes the direct action of the antiandrogen at the level of the prostate and seminal vesicles. In fact, the plasma testosterone concentration is more than doubled 6 hr after the administration of 10 mg of RU 23908 while plasma LH and testosterone levels are increased by 7- and 17-fold, respectively, after 14 days of similar daily treatment. Efficient neutralization of the androgenic action at the prostatic level in intact animals thus requires prevention of this escape phenomenon through inhibition of LH secretion. Although inhibition of LH release can be achieved by estrogen and progestins, an optimal inhibitory effect on the prostate is obtained by the combined administration of the antiandrogen with an LHRH agonist that causes a specific blockage of testicular androgen biosynthesis as well as an inhibition of the LH responsiveness to LHRH.

Androgen Antagonists↗
PubMed1984

Animal models for hormone-dependent human breast cancer. Relationship between steroid receptor profiles in canine and feline mammary tumors and survival rate.

The present study shows that canine and feline mammary tumors, like human breast tumors, can be polyreceptive, i.e., they can contain estrogen (ER), progestin (PR), androgen, glucocorticoid, and/or mineralocorticoid cytosol receptors. Furthermore, a follow-up of 45 bitches with mammary carcinoma has indicated that the survival rate is significantly higher in animals with receptor-rich (ER and/or PR) tumors. This indicates that these canine mammary tumors should be evaluated further for their suitability as an animal model for hormone-dependent human breast carcinoma.

Animals↗
PubMed1984

RU 16117, an orally active estriol-like weak estrogen.

RU 16117, the 11 alpha-methoxy derivative of ethynyl estradiol, is an orally active weak estrogen potentially effective in the treatment of estrogen-deficiency in postmenopausal women (climacteric symptoms and severe osteoporosis). Biochemical studies have shown that RU 16117, like estriol, possesses the properties characteristic of a partial estrogen agonist/antagonist. RU 16117 binds to the cytosol estrogen receptor (ER) to form a complex which dissociates much faster than the estradiol complex. This explains its lower nuclear uptake. Furthermore, the nuclear RU 16117 complex also dissociates faster than the estradiol complex. Consequently, although low doses of RU 16117 can induce the majority of the effects of estradiol (increased polymerase A and B activities, cytosol ER replenishment, progestin receptor induction, increased uterine weight), these effects are long-lived only if the dose is considerably increased or if the compound is administered repeatedly or continuously. Since RU 16117 transiently occupies available estrogen binding sites, it can prevent the full response of estradiol. Thus, under appropriate kinetic conditions, it acts as an estrogen antagonist on the above parameters and also on DMBA-induced mammary tumors in the rat. At a daily dose of 24 micrograms for a period of 4 weeks RU 16117 led to 65% reduction in the number of already-established tumors. RU 16117 inhibits basal gonadotropin secretion and decreases the LH response to LHRH. Injection of 5 micrograms s.c. to the rat in estrus markedly inhibited the spontaneous peaks of LH, FSH and PRL measured on the afternoon of expected proestrus. Low doses which block ovulation by 100% had no detectable effect on vaginal cornification, thus suggesting a greater sensitivity at the hypothalamo-pituitary level.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗