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Aldosterone is the principal endogenous mineralocorticoid in humans and regulates salt and water homeostasis. Cortisol, the major glucocorticoid, has high affinity for the mineralocorticoid receptor; however, 11beta-hydroxysteroid dehydrogenase type 2 converts cortisol to the inactive steroid cortisone in aldosterone target cells of the kidney, thus limiting the mineralocorticoid action of cortisol. Deoxycorticosterone (DOC) binds to the mineralocorticocoid receptor with high affinity and circulates at concentrations comparable to aldosterone. Severe DOC excess as is seen in 17alpha- and 11beta-hydroxylase deficiencies causes hypertension, and moderate DOC overproduction in late pregnancy is associated with hypertension. Here, we demonstrate that DOC is inactivated by the 20-ketosteroid reductase activity of the human AKR1C3 isozyme. Immunohistochemical analyses demonstrate that AKR1C3 is expressed in the mineralocorticoid-responsive epithelial cells of the renal cortical and medullary collecting ducts, as well as the colon. Our findings suggest that AKR1C3 protects the mineralocorticoid receptor from activation by DOC in mineralocorticoid target cells of the kidney and colon, analogous to cortisol inactivation by 11beta-hydroxysteroid dehydrogenase type 2.

Human aldo-keto reductases (AKR) of the 1A, 1B, 1C and 1D subfamilies are involved in the pre-receptor regulation of nuclear (steroid hormone and orphan) receptors by regulating the local concentrations of their lipophilic ligands. AKR1C3 is one of the most interesting isoforms. It was cloned from human prostate and the recombinant protein was found to function as a 3-, 17- and 20-ketosteroid reductase with a preference for the conversion of Delta4-androstene-3,17-dione to testosterone implicating this enzyme in the local production of active androgens within the prostate. Using a validated isoform specific real-time RT-PCR procedure the AKR1C3 transcript was shown to be more abundant in primary cultures of epithelial cells than stromal cells, and its expression in stromal cells increased with benign and malignant disease. Using a validated isoform specific monoclonal Ab, AKR1C3 protein expression was also detected in prostate epithelial cells by immunoblot analysis. Immunohistochemical staining of prostate tissue showed that AKR1C3 was expressed in adenocarcinoma and surprisingly high expression was observed in the endothelial cells. These cells are a rich source of prostaglandin G/H synthase 2 (COX-2) and vasoactive prostaglandins (PG) and thus the ability of recombinant AKR1C enzymes to act as PGF synthases was compared. AKR1C3 had the highest catalytic efficiency (kcat/Km) for the 11-ketoreduction of PGD2 to yield 9alpha,11beta-PGF2 raising the prospect that AKR1C3 may govern ligand access to peroxisome proliferator activated receptor (PPARgamma). Activation of PPARgamma is often a pro-apoptotic signal and/or leads to terminal differentiation, while 9alpha,11beta-PGF2 is a pro-proliferative signal. AKR1C3 is potently inhibited by non-steroidal anti-inflammatory drugs suggesting that the cancer chemopreventive properties of these agents may be mediated either by inhibition of AKR1C3 or COX. To discriminate between these effects we developed potent AKR1C inhibitors based on N-phenylanthranilic acids that do not inhibit COX-1 or COX-2. These compounds can now be used to determine the role of AKR1C3 in producing two proliferative signals in the prostate namely testosterone and 9alpha,11beta-PGF2.

We have studied the development of the adrenal gland in the rat comprising the ages ranging from 0 to 90 days after birth. The weight of the animals and that of the adrenal glands demonstrated a linear growth with time until 75 days, both in males and females. The area of the zona glomerulosa (ZG) increased in size from birth until approximately 40 days of age. After that, growth had a much smaller slope (females, r=0.84, P < 0.001; males, r=0.81, P < 0.001). Aldosterone secretion had a marked increase until 20 days of age and thereafter demonstrated a tendency for a decrease (females, r=-0.19, P < 0.02: males r=-0.26, P < 0.001). Plasma renin activity followed a trend parallel to that of aldosterone. The steroid precursor 18-OH-deoxycorticosterone (18-OH-DOC) demonstrated a different course as it increased progressively with age especially in the females (females, r=0.57, P < 0.001; males, r=0.40, P <0.001). The expression of the enzyme 3-beta-hydroxysteroid dehydrogenase (3-beta-HSD) was also studied by immunohistochemistry and it was shown to be very low at birth and starting to increase by 10 days of age. After 30/40 days of age the amount of this enzyme existing in the ZG was comparable with that of the outer zona fasciculata (ZF). We conclude that the development of the ZG in the rat has particularities that make it different from that of the rest of the cortex.

The transforming growth factor beta (TGF-beta) superfamily includes several closely related peptides including the activins and inhibins. Since we recently reported that TGF-beta 1 and beta 2 are potent inducers of steroid 5 alpha-reductase (5 alpha R), we have now studied the effects of these other peptides using primary cultures of human scrotal skin fibroblasts. Recombinant human activin A or inhibin A were added to cultured cells (2 x 10(5) cells) for 2 days in a serum free media and 5 alpha R activity was measured by the %-conversion of tracer [3H]-testosterone to dihydrotestosterone (DHT) over a 4-h period. Activin significantly stimulated 5 alpha R activity in a dose related manner (control 3.0 +/- 0.4%, activin (1.2 x 10(-9) M) 6 +/- 0.7%, P < 0.01, (2.4 x 10(-9) M) 8.5 +/- 0.6%, P < 0.001). In comparison, androgen (DHT 10(-7) M) induction of 5 alpha R was 4.7 +/- 0.2%, P < 0.05. Combined exposure of fibroblasts to activin (1.2 x 10(-9) M) and androgen (10(-7) M) did not result in additive or synergistic effect on 5 alpha R activity. In contrast, exposure of cells to an androgen (10(-7) M) and TGF-beta (2 x 10(-10) M) led to synergistic effects on 5 alpha R activity (control 1.5 +/- 0.1%, DHT 2.6 +/- 0.2% TGF-beta 1 4.8 +/- 0.5, TGF-beta 1 + DHT 9.2 +/- 1.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Dehydroepiandrosterone-sulfate (DHEA-S), the main secretory product of the human adrenal, requires the presence of steroid sulfatase, 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD), 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD), 5 alpha-reductase, and aromatase to form the active androgen dihydrotestosterone (DHT) and the estrogens 17 beta-estradiol (E2) and 5-androst-ene-3 beta,17 beta-diol (delta 5-diol) in peripheral target tissues. Because humans, along with non-human primates are unique in having adrenals that secrete large amounts of DHEA-S, the present study investigated the tissue distribution of the enzymatic activity of the above-mentioned steroidogenic enzymes required for the formation of active sex steroids in the male and female rhesus monkey. Estrone and DHEA sulfatase activities were measured in all 25 tissues examined, and with the exception of the salivary glands, estrogenic and androgenic 17 beta-HSDs were present in all the tissues examined. The adrenal, small and large intestine, kidney, liver, lung, fat, testis, prostate, seminal vesicle, ovary, myometrium, and endometrium all possess the above-mentioned enzymatic activities, thus suggesting that these tissues could possibly form the biologically active steroids E2 and DHT from the adrenal precursor DHEA-S. On the other hand, the oviduct, cervix, mammary gland, heart, and skeletal muscle possess all the enzymatic activities required to synthesize E2 from DHEA-S. The present study describes the widespread tissue distribution of steroid sulfatase, 3 beta-HSD, 17 beta-HSD, 5 alpha-reductase, and aromatase activities in rhesus monkey peripheral tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

The steroid-metabolizing enzyme, type I 17 beta-hydroxysteroid oxidoreductase (17 beta-HSOR) also called 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) plays a key role in ovarian synthesis of 17 beta-estradiol. This is the only enzyme in the steroid-metabolizing pathway which has not been localized in the human ovary by immunohistochemistry. In this study, using antibody directed against human placental cytosolic 17 beta-HSOR (type I), a single protein band with a relative molecular mass of approximately 34 kDa was demonstrated by Western analysis in both human luteinized granulosa cells and placental tissue. In placental tissue, immunoreactive type I 17 beta-HSOR was demonstrated within the syncytiotrophoblast using immunohistochemistry. In human ovary, immunoreactive type I 17 beta-HSOR was localized exclusively in granulosa cells of developing follicles, ranging from primary follicles with a single layer of cuboidal-shaped granulosa cells, preantral follicles with multiple layers of granulosa cells, and large antral follicles. No immunoreactivity was detected in spindle-shaped granulosa cells of primordial follicles, theca interna, theca externa or surrounding stroma. In the corpus luteum, type I 17 beta-HSOR immunoreactivity was localized solely in granulosa-lutein cells. For comparison, immunoreactive 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) was examined in the same tissues. Both theca interna and granulosa cells of preantral and antral follicles exhibited 3 beta-HSD staining. Primary follicles did not exhibit detectable 3 beta-HSD in either granulosa or theca cells.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ hybridization and immunohistochemical localization of cytochrome P450 cholesterol side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), cytochrome P450 17 alpha-hydroxylase (P450c17) and cytochrome P450 aromatase (P450arom) was performed in 50 morphologically normal human premenopausal ovaries, and correlated these findings with their endometrial phase. In general, mRNA expression of these enzymes examined by in situ hybridization were in good agreement with immunolocalization examined by immunohistochemistry. Expression of P450scc, 3 beta HSD and P450c17 was observed in large-sized preantral follicles, consisting of more than five layers of granulosa cells, preovulatory follicles, corpora lutea, and some degenerating corpora lutea and atretic follicles in all endometrial phases. Several follicles and/or corpora lutea positive for these enzymes were observed in the same ovary. Expression of P450arom was generally observed in only one follicle (antral or preovulatory follicle) or corpus luteum per case in mid proliferative to premenstrual phase, and was not observed in menstrual to early proliferative phase. These findings indicated that (1) expression of steroidogenic enzymes was associated with the continual human ovarian process including follicular development and atresia, and (2) especially, P450arom expression may occur only in a selected antral follicle and may have an important role in dominant follicular development.

The present paper examines the steroidogenic responsiveness of immature porcine Leydig cells in primary culture. Both testosterone (T) and dehydroepiandrosterone sulfate (DHAS) secretion were measured under basal conditions and after stimulation with human chorionic gonadotropin (hCG) (25 ng/ml). In medium supplemented with insulin, transferrin, epidermal growth factor (3H) and 0.1% calf serum, cells survived 3-5 days in culture. The production of steroids (under hCG stimulation) is poor on day 0-1 of the culture. On day 2-4 basal T and DHAS levels are 1.9 and 17.0 ng/10(6) cells/24 h. The addition of hCG stimulated T and DHAS production 19- and 6-fold respectively and the average productions were 37 and 109 ng/10(6) cells/24 h. Increasing the serum to 0.5% did not change the viability of the cultures, but increased hCG stimulated T and DHAS production (183 and 188 ng/10(6) cells/24 h). The addition of alpha-tocopherol (vitamin E) to 0.1% calf serum led to a 4-fold increase in stimulated T production (142 ng/10(6) cells/24 h) and maintained full cell viability for more than 5 days. Measurement of 3 beta-ol steroid dehydrogenase activity indicates that the amount of enzyme is 4 times higher at day 2 than at day 0 and 1 (with or without hCG), suggesting a spontaneous maturation of the cells in culture. This might explain the increased T production with time in culture. In cumulative experiments (24 h) the cells do not seem to be desensitized to hCG stimulation following prolonged exposure to 25 ng hCG since the daily steroid production is increasing with time in culture. However, kinetic studies show that steroidogenesis is not linear over a 24 h period. In cumulative experiments the steroid production stops between 12 and 16 h following hCG exposure (5 and 100 ng/ml) and resumes following a medium change. These results suggest that some inhibitory compounds are accumulated in the medium and are controlling the Leydig cell function. Moreover high doses of hCG (100 ng/ml) result in a lower production of steroids and an earlier plateau in the case of DHAS. These results demonstrate that porcine Leydig cells can live and differentiate in hormone- and vitamin-supplemented medium and that auto-feedback mechanisms inhibiting steroid accumulation take place under in vitro conditions.