Steroid hormones and the fertilizing capacity of spermatozoa

The effects of eleven different steroid hormones on $\text{in vitro}$ development of fertilizing capacity by hamster sperm were examined. Capacitation of epididymal sperm occurred only in the presence of female genital tract secretions. Fertilizing ability of sperm was poor if estradiol-17β, cortisol, chlormadinone acetate, medroxyprogesterone acetate, or megestrol acetate were present in the incubation medium at 10^?5M, whereas similar concentrations of estradiol-17α, progesterone, norethisterone acetate, ethynodiol diacetate, or norgestrel had little effect. Testosterone was a weak inhibitor of capacitation. Capacitation activity of female uterus and oviduct washings was higher at estrus than diestrus. This activity was reduced by treating intact animals with progesterone, cortisol, or testosterone, but increased by estradiol-17β or HCG. Estradiol-17α has no effect. Activity was low in pregnant or ovariectomized hamsters. Treatment of ovariectomized animals with estradiol-17β increased capacitation activity, but estradiol-17α, HCG or progesterone treatment was ineffective.     

Influence of progestins on serum hormone levels in postmenopausal women with advanced breast cancer--II. A differential effect of megestrol acetate and medroxyprogesterone acetate on serum estrone sulfate and sex hormone binding globulin

Serum estradiol, estrone, estrone sulfate and sex hormone binding globulin were measured in 10 postmenopausal patients with advanced breast cancer receiving sequential treatment with medroxyprogesterone acetate and megestrol acetate. Treatment with megestrol acetate caused a non-significant reduction in serum estradiol (mean reduction of 19%, 0.05 less than P less than 0.1) but significant reductions in serum estrone (mean reduction of 20%, P less than 0.02) and serum estrone sulfate (mean reduction of 54%, P less than 0.005) compared to treatment with medroxyprogesterone acetate. In contrast, treatment with medroxyprogesterone acetate reduced serum sex hormone binding globulin more compared to treatment with megestrol acetate (mean reduction of 69%, P less than 0.01). These findings suggest that the two progestins have differential effects on serum hormone levels. The finding that treatment with megestrol acetate causes a significant reduction in serum estrone sulfate level warrants further investigations of this potentially important mechanism of action of this drug in advanced breast cancer.     

Effects of cyproterone acetate on adrenal steroidogenesis in vitro

The effects of cyproterone acetate (CA) on steroidogenesis in isolated guinea-pig adrenal cells have been investigated by measuring the production of cortisol, its immediate precursors (11-deoxycortisol and 17-hydroxyprogesterone), and adrenal androgens (delta 4-androstenedione and dehydroepiandrosterone). Used at a dose of 2 micrograms/ml, CA provoked a sharp drop in the production of cortisol, aldosterone and 11-deoxycortisol. By contrast, 17-hydroxyprogesterone, delta 4-androstenedione and dehydroepiandrosterone were increased, which suggests that 21-hydroxylase activity is inhibited. With concentrations above 2 micrograms/ml CA, it would seem to be the 3-beta-ol-dehydrogenase-delta 4,5-isomerase complex that is affected, since dehydroepiandrosterone exhibited a sudden increase, whereas 17-hydroxyprogesterone and delta 4-androstenedione showed a relative decrease. The enzymatic system or systems involved therefore appear to be linked to the concentration of CA used but, whatever the case, the drop in cortisol production is accompanied by a decrease in aldosterone and an increase in adrenal androgen levels.     

Metabolism of megestrol acetate and related progesterone analogues by liver preparations in vitro

1. The rates of metabolism of megestrol acetate, 17alpha-acetoxy-6alpha-methylprogesterone, 6alpha-methylprogesterone, 17alpha-acetoxyprogesterone and progesterone by liver microsome-supernatant fractions from female rats and rabbits have been compared. 2. Introduction of the 6alpha-methyl group into the progesterone molecule markedly decreased the metabolism by liver microsome-supernatant preparations in the rat but not in the rabbit. When 17alpha-acetoxy was the substituting group, metabolism was diminished in the rabbit but not in the rat preparations. Introduction of both the 6alpha-methyl and 17alpha-acetoxy groups into the progesterone molecule markedly decreased the rate of metabolism by liver microsome-supernatant preparations of both species. The Delta(6)-bond in megestrol acetate confers additional resistance to metabolism by rabbit-liver preparations. 3. It is proposed that the observed inhibition of metabolism by these substituents in the progesterone molecule partly or wholly explains the enhanced activity of megestrol acetate.     

Affinities of progestogen and estrogen receptors in rabbit uterus for synthetic progestogens

The affinities of progestogen and estrogen receptors of rabbit uterus for a number of synthetic progestogens in clinical use and some analogues have been measured. Progesterone, 17-hydroxyprogesterone caproate, the chlormadinone, megestrol and cyproterone acetates had similar affinities for the progestogen receptor. Medroxyprogesterone acetate and particularly DU-41164 possessed much higher affinities. 17-hydroxyprogesterone or other agents with a free 17-hydroxyl had much lower receptor affinities than the corresponding 17-esters.Of the nortestosterone derivatives tested, norethisterone equalled progesterone in affinity for the progestogen receptor while d-norgestrel and Wy-4355 were more active. Norethynodrel and ethynodiol diacetate had much lower receptor affinities than progesterone. These results are discussed in relation to possible metabolic bioactivation.Only norethynodrel and ethynodiol (free alcohol) showed marked affinity for the estrogen receptor.     

Influence of progestins on serum hormone levels in postmenopausal women with advanced breast cancer--I. General findings

The influence of oral high dose progestin (medroxyprogesterone acetate, MPA and megestrol acetate, MA) treatment on serum hormone levels was studied in ten postmenopausal women with advanced breast cancer. The gonadotropins and ACTH were significantly reduced by greater than 50 and 23%, respectively. Serum cortisol, DHEAS, androstenedione and testosterone were all significantly reduced (mean reduction between 64 and 76%), while serum estrone, estradiol and estrone sulfate were significantly reduced by 20-30%. Sex hormone binding globulin (SHBG) and corticosteroid binding globulin (CGB) were reduced by 68 and 25%, respectively. Although the dose of MA used (160 mg/day) was only 1/6 of the MPA dose (1000 mg/day), the mean serum level of MA was 2-fold higher than the mean serum level of MPA. MPA treatment gave a more pronounced suppression of SHBG than MA treatment, while estrone sulfate levels were more suppressed by MA. These findings suggest a differential effect of MPA and MA on certain plasma hormones, possibly of importance for understanding the mechanism of action of the two drugs. The reduction of estrone sulfate may be beneficial for the action of MA against breast cancer.     

A simple in vitro approach to the estimation of the biopotency of drugs affecting adrenal steroidogenesis

Dispersed guinea-pig adrenal cells can be maximally stimulated to secrete cortisol by adrenocorticotrophin (ACTH greater than 50 ng/l). Further, this stimulation appears to be specific to ACTH alone, with other naturally occurring chemicals (e.g. steroids, protein hormones) at supra-physiological concentrations being without effect on cortisol production. The effect of drugs of differing structure and therapeutic function (aminogluthethimide, metyrapone, trilostane, 17-ketotrilostane, danazol, epostane, megestrol acetate, stanozolol and etomidate) on ACTH-stimulated (50 ng/l) cortisol production has been tested in this system. All the drugs depressed steroid output in a similar dose-related fashion. The concentration of drug which inhibited cortisol output by 50% was (mumol/l, mean +/- SEM): etomidate 0.097 +/- 0.002: epostane 0.44 +/- 0.02: 17-ketotrilostane 0.55 +/- 0.04: trilostane 1.3 +/- 0.1: metyrapone 3.5 +/- 0.6: megestrol acetate, 11 +/- 2: danazol 22 +/- 2: aminogluthethimide 41 +/- 5: stanozolol 50 +/- 4. Thus, etomidate, an anaesthetic, is more potent than the established anti-steroidogenic drugs metyrapone, aminogluthethimide and trilostane. Further, direct anti-steroidogenic effects have been demonstrated for megestrol acetate and stanozolol for the first time. We conclude that this technique offers a promising new approach to the assessment of biological potency of drugs affecting endocrine tissues.     

An adrenocortical tumor secreting weak mineralocorticoids

An adrenocortical carcinoma (15.5 g) secreting excessive amounts of steroids with weak mineralocorticoid activity in a 25-year-old woman was studied with particular reference to its in vivo and in vitro secretions of steroids. Severe hypertension, occasional low serum potassium and suppressed PRA were the major clinical findings, and were improved with removal of the tumor. In the preoperative stage, plasma levels of 11-deoxycorticosterone, 18-hydroxy-11-deoxycorticosterone, corticosterone and 18-hydroxycorticosterone were all increased. However, the plasma level of aldosterone was repeatedly normal. Although plasma levels of pregnenolone, 17-hydroxypregnenolone, progesterone and 17-hydroxyprogesterone were very high, those of other late step steroids, i.e. 11-deoxycortisol, cortisol, dehydroepiandrosterone, androstenedione and testosterone were almost normal. From these findings, a major etiological role of weak mineralocorticoids such as 11-deoxycorticosterone, 18-hydroxycorticosterone and corticosterone in her hypertension was suggested. Pregnenolone and 17-hydroxypregnenolone in tumor tissue were increased, but 11-deoxycorticosterone, corticosterone, aldosterone, cortisol and adrenal androgens such as dehydroepiandrosterone, androstenedione and testosterone were below normal or low normal. In vitro production of 11-deoxycorticosterone, aldosterone or cortisol by the tumor tissue slices was very low and scarcely responded to synthetic ACTH.     

Dexamethasone-suppressible hypercorticosteronism in two 46,XX subjects with ambiguous genitalia and ovarian cysts. Partial defect of 17 alpha-hydroxylase or 17-20-desmolase

The paradoxical association of female pseudohermaphroditism and androgen deficiency was observed in two 46,XX subjects with high corticosterone plasma levels. Subject 1 has been declared a boy due to clitoris enlargement; she had no vagina and uterus. Subject 2 had ambiguous external genitalia. In both, at age 27 and 17 years, fusion of outer labia, impuberism, ovarian cysts, and histologically normal ovarian tissue were observed. Blood pressure was normal. Basal cortisol levels were normal but unresponsive to ACTH. Progesterone levels were 40 and 62 ng/ml and rose after ACTH (50 and 79 ng/ml). 17-hydroxyprogesterone levels were 25 and 21 ng/ml and did not rise after ACTH. Corticosterone levels were 70 and 92 ng/ml and rose after ACTH (110 and 180 ng/ml). All three steroids were suppressed by dexamethasone. Androgen and estrogen levels were at or below the lower limit for normal women. The sex steroid levels obtained by radioimmunoassay in plasma and a follicular cyst fluid were confirmed by isotope dilution-mass spectrometry. We suggest that the sexual ambiguousness resulted from an excessive production of gestagenic steroids during fetal life, and that the enzyme defect is either a partial 17 alpha-hydroxylase defect combined with a peripheral production of 17-hydroxyprogesterone, or else a partial 17-20-desmolase defect with a secondary 21-hydroxylase defect limited to the cortisol pathway.     

Structural requirements for progesterone binding to the hepatic endoplasmic reticulum in the female rat

Microsomes isolated from the liver of the female rat specifically bind progesterone. The progesterone-microsomal complex shows highly specific characteristics. The binding is probably associated with the carbonyl groups at positions C-20 and C-3. Other steroids compete for microsomal binding sites less effectively. Competition for progesterone binding sites by other steroids in percentages: testosterone 33; testosterone propionate, 9; 17-methyltestosterone, 23.2; cortisol, 6.4; estradiol-17 beta, 1.8; 17 alpha-ethynyl estradiol, 4.7; mestranol, 1.0; norethynodrel, 4.5; ethisterone, 7.1; lynestrenol, 4.3; medroxyprogesterone, 23.3; medroxyprogesterone acetate, 15.2; 5 alpha-pregnane-3,20-dione, 47.6; 5 beta-pregnane-3,20-dione, 20.7; pregnenolone, 14.8; 6-methylpregnenolone, 1.2; 16 alpha-methylpregnenolone, 3.8%; 20 beta-hydroxy-4-pregnen-3-one, 2.8; 3 beta-hydroxy-5 alpha-pregnan-20-one, 5.2; 4-pregnene-3 beta, 20 beta-diol, 2.1; 11 alpha-hydroxyprogesterone 21.0; 16 alpha-hydroxyprogesterone, 7.9; 17-hydroxyprogesterone, 26.7; 16 alpha, 17-epoxyprogesterone, 2.7; 16 alpha-methylprogesterone, 3.8; 6-methylpregnenolone, 1.2; 16 alpha-methylpregnenolone, 3.8; promegestone, 27.0. 3 beta-Hydroxy-5 beta-pregnan-20-one, 3 alpha-hydroxy-5 beta-pregnan-20-one, 5-pregnene-3 beta,20 beta-diol, 5-pregnene-3 beta, 20 alpha-diol; 5 alpha-pregnane-3 beta, 20 beta-diol, 5 alpha-pregnane-3 beta, 20 alpha-diol, 5 beta-pregnane-3 alpha, 20 alpha-diol, 5 beta-pregnane-3 alpha, 20 alpha-diol diacetate, 5 beta-pregnane-3 alpha, 20 beta-diol, 3 alpha, 17-dihydroxy-5 beta-pregnan-20-one, 17-hydroxypregnenolone, 6-methyl-17-hydroxypregnenolone, pregnenolone-16 alpha-carbonitrile, dihydrotestosterone and cholesterol show no competition at all. The varying degree of competition by different steroids is unrelated to their lipid solubility.     

Stimulatory effect of synthetic progestins currently used for the treatment of prostate cancer on growth of the androgen-sensitive Shionogi tumor in mice

In order to assess the androgenic activity of synthetic progestins currently used as "antiandrogens" for the treatment of prostate cancer in men, the effect of a series of these compounds has been studied in mice on the growth of the androgen-sensitive Shionogi tumor. Female mice (DD/S strain) were inoculated subcutaneously with 10(6) viable cells and divided into groups who received, respectively, the synthetic "progestins" medroxyprogesterone acetate (MPA), megestrol acetate (MEG), cyproterone acetate (CPA) or chlormadinone acetate (CMA), compared with the non-steroidal antiandrogen Flutamide (Flu), each administered at the twice-daily dose of 250 micrograms. Each synthetic "progestin" exerted a marked stimulatory effect on the growth of the tumor. The most impressive effect on growth was observed with MPA. In fact, in MPA-treated mice, tumor size was 17 times larger than control at 4.92 +/- 0.36 cm2/mouse 21 days after inoculation. CPA, CMA and MEG also stimulated the growth of this androgen-sensitive tumor, the percentages of stimulation of tumor size being 3.1-, 3.2- and 11.0-fold above control, respectively, on day 21, while Flu had no significant stimulatory effect. The present data clearly show that all the above-mentioned progestins have variable levels of stimulatory activity on the growth of the androgen-sensitive Shionogi tumor and indicate that such drugs are unlikely to be recommendable for the treatment of prostate cancer.     

Non-genomic effects of progestins--inhibition of cell growth and increased intracellular levels of cyclic nucleotides

The anti-proliferative effect of progestins was studied in human transformed cell lines from the uterine cervix (C-4I, C33A and Me-180). Progestins caused a concentration-dependent inhibition of proliferation. The maximum tested concentration (2.6-3.2 microM) inhibited C-4I cell growth by the following order of potency: progesterone (56%) > medroxyprogesterone (38%) > megestrol acetate (25%). The sensitivity, expressed as I(25) (the concentration that caused 25% inhibition of growth), showed the same order: progesterone (7.7 nM) > medroxyprogesterone (78 nM) > megestrol acetate (570 nM). The intracellular levels of cGMP and cAMP were elevated and the cellular export of these cyclic nucleotides was inhibited by a similar order of potency. The C-4I cell line was devoid of progesterone-, estrogen-, androgen- and glucocorticoid-receptors. In addition, the antiprogestins mifepristone, onapristone and ZK-112993 did not block the anti-proliferative effect of progesterone. On the other hand, antiprogestins (2.3 nM) appeared to have some progesterone-like ("mimetic") activity with inhibition of C-4I cell growth; mifepristone (11%), onapristone (12%) and ZK-112993 (16%). The observed effects of progestins and antiprogestins on C-4I cells were also presented in C33A cells (16% androgen receptor positive) and Me-180 cells (22% progesterone receptor positive, 9% androgen receptor positive and 17% glucocorticoid receptor positive). This study suggests that a non-genomic mechanism contributes to the anti-proliferative effect of progestins.     

Progestins and breast cancer

In the last years there has been an extraordinary development in the synthesis of new progestins. These compounds are classified, in agreement with their structure, in various groups which include progesterone, retroprogesterones, 17-hydroxyprogesterones, 19-norprogesterones, 17-hydroxyprogesterone derivatives, androstane and estrane derivatives. The action of progestins is a function of many factors: its structure, affinity to the progesterone receptor or to other steroid receptors, the target tissue considered, the biological response, the experimental conditions, dose, and metabolic transformation. The information on the action of progestins in breast cancer patients is very limited. Positive response with the progestins: medroxyprogesterone acetate and megestrol acetate was obtained in post-menopausal patients with advanced breast cancer. However, extensive information on the effect of progestins was obtained in in vitro studies using hormone-dependent and hormone-independent human mammary cancer cell lines. It was demonstrated that in the hormone-dependent breast cancer cells, various progestins (nomegestrol acetate, tibolone, medrogestone, promegestone) are potent sulfatase inhibitory agents. The progestins can also involve the inhibition of mRNA of this enzyme. In another series of studies it was also demonstrated that various progestins are very active in inhibiting the 17β-hydroxysteroid dehydrogenase for the conversion of estrone to estradiol. More recently it was observed that the progestins promegestone or medrogestone stimulate the sulfotransferase for the formation of estrogen sulfates. Consequently, the blockage in the formation of estradiol via sulfatase, or the stimulatory effect on sulfotransferase activity, by progestins can open interesting and new possibilities in clinical applications in breast cancer.     

Relationship between functional activity of the adrenal glands and gonads in monkeys during puberty]

Testicular and adrenal cortex endocrine functions were simultaneously tested in pubertal baboons (papio hamadryas) during one year. Concentrations of androgens (testosterone, 5 alpha-dihydrotestosterone, dehydroepiandrosterone), corticosteroids (cortisol, progesterone, 17-hydroxyprogesterone, 17-hydroxypregnenolone) and aldosterone were determined in blood of the experimental monkeys by radioimmunoassay. It was shown that with increasing androgen (testosterone and dihydrotestosterone) levels in blood of the pubertal monkeys there was a significant decrease of corticosteroid concentration which was most pronounced in the monkeys with maximum increase of testosterone level. Described hormonal changes did not influence aldosterone concentration.     

Interaction of [3H]nomegestrol acetate with cytosolic progesterone receptors from the rat uterus

The binding characteristics of the progestin 17 alpha-acetoxy-6-methyl-19-[3H]norpregna-4,6-diene-3,20-dione, nomegestrol acetate ([3H]NOM-Ac) to progesterone receptors (PgRs) of uterus were determined in the rat. Scatchard plot analysis of the equilibrium binding data showed that [3H]NOM-Ac binds to uterine PgR with a Kd of 5.44 +/- 1.27 nM and a Bmax of 1.51 +/- 0.11 pmol/mg protein. Analysis of dissociation kinetics showed that [3H]NOM-Ac dissociates slowly from the PgR, k - 1 = 4.9 +/- 0.5 10(-5) s-1. Competition experiments against [3H]NOM-Ac showed the specificity of the binding with a sequence in relative affinity as follows: ORG 2058 greater than P greater than NOM-Ac greater than medroxyprogesterone acetate greater than megestrol acetate greater than cyproterone acetone greater than NOM.     

Analysis of the androgenic activity of synthetic "progestins" currently used for the treatment of prostate cancer

In order to assess the androgenic activity of synthetic "progestins" currently used as "antiandrogens" for the treatment of prostate cancer in men, the effect of a series of these compounds has been measured following 14 days of treatment of adult castrated rats on specific and sensitive parameters of androgenic activity, namely ventral prostate weight and prostatic ornithine decarboxylase (ODC) activity. Medroxyprogesterone acetate (MPA) is almost equipotent with 5 alpha-dihydrotestosterone (DHT), a 49% increase in prostatic weight being observed at the low dose of 0.15 mg, twice daily (P less than 0.01). Megestrol acetate (Megace), chlormadinone acetate (CMA) and spironolactone were less potent but caused a 36-59% increase in prostatic weight at the highest dose used, namely 10 mg. At the 5 mg dose, cyproterone acetate (CPA) caused a 75% increase in prostatic weight. The androgenic activity of the compounds is even more clearly illustrated by their marked stimulatory effect on prostatic ornithine decarboxylase (ODC) activity. MPA, at the low dose of 0.15 mg, caused a 20-fold increase (relative to the effect of placebo) in the activity of the enzyme while the same dose of DHT caused a 15-fold stimulation of enzymatic activity. At the 10 mg dose, megestrol acetate, CMA and spironolactone caused 13.1, 11.8 and 8.6-fold stimulations of ODC activity, respectively. Flutamide, on the other hand, had no stimulatory effect on either ventral prostate weight or prostatic ODC activity. In agreement with glucocorticoid activity, MPA, megestrol acetate and CMA caused a marked inhibition (45-64%) of adrenal weight. The present data show that MPA is a highly potent androgen while megestrol acetate, CMA, CPA and spironolactone have lower but significant androgenic activity on all the parameters measured. It should be added that MPA, megestrol acetate and CMA are completely devoid of antiandrogenic activity while spironolactone shows weak antiandrogen action and CPA is a mixed agonist-antagonist. Flutamide, the compound used as reference, is the only compound devoid of any androgenic action and is thus acting as a pure antiandrogen on both ventral prostate weight and prostatic ODC activity. The present data have major implications for the choice of drug to be used for the treatment of androgen-sensitive diseases, especially prostate cancer. As shown by the present data, the synthetic "progestins" so-far available all possess variable levels of androgenic activity and are thus not recommended for the treatment of prostate cancer.     

Effects of surgery and epidural or general anaesthesia on testosterone, 17-hydroxyprogesterone and cortisol plasma levels in prepubertal boys

Testosterone (T), 17-hydroxyprogesterone (17P) and cortisol (F) plasma levels have been measured in two groups of prepubertal boys before and during surgery under general anaesthesia (Group 1) and epidural anaesthesia (Group 2) respectively. The mean plasma levels of T, 17P and F increased significantly (P less than 0.05; P less than 0.001; P less than 0.005, respectively) during surgery in Group 1; in Group 2 the plasma levels of T and F did not show any significant variation, whereas 17P significantly increased (P less than 0.05). However the mean level reached by 17P in Group 2 was significantly lower (P less than 0.005) than that observed in Group 1. No significant variation of LH and FSH plasma levels was observed in either group. Our report suggests that the modifications of T and 17P plasma levels observed during surgery under general anaesthesia (GA) are probably due to the stress induced adrenal response. This response can be inhibited or reduced by epidural anaesthesia (EA).     

Exogenous and endogenous corticosteroids modulate blood-brain barrier development in the ovine fetus

We previously reported decreases in blood-brain barrier permeability in the ovine fetus at 80% of gestation after antenatal corticosteroids and shown that permeability is not reduced in newborn lambs after postnatal corticosteroids. We now test the hypotheses that exogenous antenatal corticosteroids decrease blood-brain barrier permeability at 60% but not 90% of gestation in ovine fetuses and that endogenous increases in plasma cortisol concentrations are associated with ontogenic decreases in barrier permeability during gestation. Chronically instrumented ovine fetuses were studied 12 h after the last of four 6-mg dexamethasone or placebo injections were given 12 h apart over 48 h to ewes. Fetuses at 80% of gestation from placebo-treated ewes studied under the same protocol were also included. Blood-brain barrier function was quantified with the blood-to-brain transfer constant (K(i)) to alpha-aminoisobutyric acid. K(i) values were lower in cerebral cortex, caudate nucleus, hippocampus, superior colliculus, thalamus, medulla, and cervical spinal cord in fetuses of dexamethasone- than placebo-treated ewes at 60% but not 90% of gestation. Regional brain K(i) values demonstrated inverse correlations with increases in gestation and plasma cortisol concentrations in most brain regions. We conclude that maternal treatment with exogenous corticosteroids was associated with decreases in blood-brain barrier permeability at 60% but not 90% of gestation and that increases in gestation and endogenous cortisol concentrations were associated with ontogenic decreases in barrier permeability during fetal development.     

A cluster of missense mutations at Arg356 of human steroid 21-hydroxylase may impair redox partner interaction

Lesions in the gene encoding steroid 21-hydroxylase result in congenital adrenal hyperplasia, with impaired secretion of cortisol and aldosterone from the adrenal cortex and overproduction of androgens. A limited number of mutations account for the majority of mutated alleles, but additional rare mutations are responsible for the symptoms in some patients. A total of 11 missense mutations has previously been implicated in this enzyme deficiency. We describe two novel missense mutations, both affecting the same amino acid residue, Arg356. The two mutations, R356P and R356Q, were reconstructed by in vitro site-directed mutagenesis, the proteins were transiently expressed in COS-1 cells, and enzyme activity towards the two natural substrates, 17-hydroxyprogesterone and progesterone, was determined. The R356P mutant reduced enzyme activity to 0.15% towards both substrates, whereas the R356Q mutant exhibited 0.65% of normal activity towards 17-hydroxyprogesterone, and 1.1% of normal activity towards progesterone. These activities correspond to the degrees of disease manifestation of the patients in whom they were found. Arg356 is located in a region which recently has been implicated in redox partner interaction, by modelling the structure of two other members of the cytochrome P450 superfamily. Of the 11 previously described missense mutations, three affect arginine residues within this protein domain. With the addition of R356P and R356Q, there is a clear clustering of five mutations to three closely located basic amino acids. This supports the model in which this protein domain is involved in redox partner interaction, which takes places through electrostatic interactions between charged amino acid residues. Received:17 December 1996 / Revised: 28 January 1997     

Progesterone transformations by three species ofHumicola

Five isolates belonging to three species of the genusHumicola were tested in this study for their ability to transform progesterone. An oxidative splitting of the side chain of progesterone with the formation of androst-4-ene-3,17-dione, testosterone and testololactone was achieved by all isolates tested ofH. fuscoatra andH. grisea. H. hyalothermophila transformed progesterone to 11α-, 11β-, 17α- and 21-hydroxyprogesterone and a dihydroxyl product (11α, 17α-dihydroxyprogesterone) with the addition of two trihydroxyl products,viz. cortisol and epicortisol. Qualitative and quantitative analysis of the different products obtained when a selective isolate of each species acted on progesterone were conducted. The chromatographic resolution of the mixture products obtained when the selective isolate of each ofH. fuscoatra andH. grisea had acted individually on 1 g progesterone revealed the presence of 25 and 20% unchanged progesterone, 20 and 22% androst-4-ene-3,17-dione, 25 and 23% testosterone and 30 and 35% testololactone, respectively. Seventy-four % of progesterone were bioconverted byH. hyalothermophila into 21-hydroxyprogesterone (6%), 17α-hydroxyprogesterone (5%), 11α-hydroxyprogesterone (11%), 11β-hydroxyprogesterone (12%), 11α,17α-dihydroxyprogesterone (5%), cortisol (21%) and epicortisol (13%). This is the first record of conversion of progesterone to both cortisol and epicortisol byH. hyalothermophila.