Estrogen-like effect of 5-androstene-3 beta,17 beta-diol on the induction of fetal thymidine kinase in the rat uterus

New insights into the protective effects of DHEA1)

Numerous studies investigated the effects of pharmacological doses of DHEA in animals. Among protective effects, antiglucocorticoid potencies, triggering and modulation of immunity and anticancerous effects were reported. Because DHEA levels decrease in aging humans, this steroid has been assayed as replacement therapy in elderly volunteers without striking evidence for beneficial effects. Examination of the investigations carried out in animals lead to suspect that, rather than DHEA, its metabolites produced in tissues could be responsible for some of the observed effects. Known as the "mother steroid", DHEA is a precursor for androgenic and estrogenic steroid hormones. In addition, DHEA is hydroxylated at the 7α position by the cytochrome P450 7B1 (CYP7B1), and the 7α-hydroxy-DHEA produced is a substrate for the 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) which converts it into 7β-hydroxy-DHEA. Both 7-hydroxylated metabolites were shown to favor the onset of immunity in mice and the activation of memory T cells in humans. Other DHEA and testosterone-derived metabolites, namely epiandrosterone and 5α-androstane-3β,17β-diol, are also substrates for the CYP7B1 and their 7α-hydroxylated products were also converted into the 7β epimer by the 11β-HSD1. When assayed at doses 104 lower than DHEA, 7β-hydroxy-epiandrosterone was shown to shift the prostaglandin metabolism patterns from prostaglandin E2 (PGE2) to PGD2 production, thus triggering the resolution of inflammation. In addition, 7β-hydroxy-epiandrosterone (1 nM) exerted the same effects as tamoxifen (1 μM) on the proliferation of MCF-7 and MDA-231 human breast cancer cells. These findings suggest that the observed effects of 7β-hydroxy-epiandrosterone could be mediated by estrogen receptors. This overview of recent research implies that DHEA does not act directly and that its effects are due to its metabolites when produced in tissues. Treatments with DHEA should take into account the target tissue abilities to produce the desired metabolites through the two key enzymes, CYP7B1 and 11β-HSD1.

Adrenarche and bone modeling and remodeling at the proximal radius: weak androgens make stronger cortical bone in healthy children

Adrenarche, the physiological increase in adrenal androgen secretion, may contribute to better bone status. Proximal radial bone and 24-h urinary steroid hormones were analyzed cross-sectionally in 205 healthy children and adolescents. Positive adrenarchal effects on radial diaphyseal bone were observed. Obviously, adrenarche is one determinant of bone mineral status in children.

INTRODUCTION

Increased bone mass has been reported in several conditions with supraphysiological adrenal androgen secretion during growth. However, no data are available for normal children. Therefore, our aim was to examine whether adrenal androgens within their physiological ranges may be involved in the strengthening of diaphyseal bone during growth.

METHODS

Periosteal circumference (PC), cortical density, cortical area, bone mineral content, bone strength strain index (SSI), and forearm cross-sectional muscle area were determined with peripheral quantitative computed tomography (pQCT) at the proximal radial diaphysis in healthy children and adolescents. All subjects, aged 6-18 years, who collected a 24-h urine sample around the time of their pQCT analysis (100 boys, 105 girls), were included in the present study, and major urinary glucocorticoid (C21) and androgen (C19) metabolites were quantified using gas chromatography-mass spectrometry.

RESULTS AND CONCLUSIONS

We found a significant influence of muscularity, but not of hormones, on periosteal modeling (PC) before the appearance of pubic hair (prepubarche). Similarly, no influence of total cortisol secretion (C21) was seen on the other bone variables. However, positive effects of C19 on cortical density (p < 0.01), cortical area (p < 0.001), bone mineral content (p < 0.001), and SSI (p < 0.001)--reflecting, at least in part, reduction in intracortical remodeling-were observed in prepubarchal children after muscularity or age had been adjusted for. This early adrenarchal contribution to proximal radial diaphyseal bone strength was further confirmed for all cortical variables (except PC) when, instead of C19 and C21, specific dehydroepiandrosterone metabolites were included as independent variables in the multiple regression model. During development of pubic hair (pubarche), muscularity and pubertal stage rather than adrenarchal hormones seemed to influence bone variables. Our study shows that especially the prepubarchal increase in adrenal androgen secretion plays an independent role in the accretion of proximal radial diaphyseal bone strength in healthy children.

Estrogen receptor and C19-5-ene-steroid concentrations in the nuclear fraction from human breast carcinoma tissue

The adrenal-derived estrogen 5-androstene-3 beta,17 beta-diol (ADIOL) is estrogenic at the concentrations found in the blood of Western women. We have now measured the concentrations of both ADIOL and the estrogen receptor (ER) in the nuclear fraction (800 g pellet) of 89 primary human mammary tumors. No difference was found in nuclear ADIOL concentrations in tumors from 45 pre- and 44 postmenopausal women. Significantly higher nuclear ADIOL concentrations were found in 49 ER negative tumors compared to 40 ER positive tumors (P < 0.005). A similar relationship applied in the postmenopausal group (P = 0.01) and the premenopausal group, but in this latter instance failed to reach significance (P = 0.1). In ER positive tumors there was no correlation between ADIOL and ER nuclear levels. ADIOL was present in the total particulate fraction (100,000 g pellet) at twice the concentration found in the nuclear 800 g pellet and again no difference was found in its concentration in tumors from 20 pre- compared to 34 postmenopausal women. Dehydroepiandrosterone was also measured in the 800 g fraction of 45 tumors and its concentration, which was some 10-fold higher than ADIOL and significantly correlated with that steroid, was again independent of menopausal status. The higher concentration of C19-5-ene-steroids in ER negative cellular fractions could be due to differences in their metabolism; ER negative tumors either lack, or possess very low levels of, hydroxysteroid sulfotransferase which catalyzes formation of sulfate esters of C19-5-ene-steroids previously observed to be major metabolites produced by ER positive cells. Higher concentrations of free steroids in ER negative cells would then be available for combination with membranes and non-specific binding sites throughout the cell.

Human breast cancer: concerted role of diet, prolactin and adrenal C19-delta 5-steroids in tumorigenesis

The low incidence of breast cancer in Japan disappears within 2 generations in migrant Japanese in the USA. This is of fundamental importance if we are to understand, and perhaps reverse, the high rate seen in Western countries. Diet is the most likely factor involved, and a review of the topic of diet, body mass index, and gain in adult body mass, supports a relationship between these factors and breast-cancer risk in post-menopausal, but not pre-menopausal, women. A direct link between nutritional factors and secretion of the hormones prolactin and dehydroepiandrosterone sulfate is proposed. An estrogen 5-androstene-3 beta, 17 beta-diol is formed peripherally from the latter steroid, and in Western women attains a blood concentration at which it is biologically active. Thus diet/fat provides factors, viz., fatty acids, prolactin and estrogen, which in concerted fashion provide a milieu conducive to mammary tumorigenesis.