The Non-Aromatic Δ5-Androstenediol Derivative of Dehydroepiandrosterone Acts as an Estrogen Agonist in Neonatal Rat Osteoblasts through an Estrogen Receptor α-related Mechanism.

Purpose: It has been proposed that DHEA influences bone formation through, bioconversion to 17ß-estradiol; however, DHEA is converted to Δ5-androstenediol (Δ5-Adiol), a metabolite with estrogenic potential involved in diverse biological process. To gain new insight into the role of Δ5-Adiol in bone cells, we examined DHEA and Δ5-Adiol effects in neonatal rat and human hFOB1.19 osteoblasts. Methods: Osteoblast activity was assessed by analyzing proliferation, alkaline phosphatase activity, and expression of OSX and ALPL. We also examined binding affinities for osteoblast-ER and transcriptional activation of human (h)ERα, hERß or hAR in U2-OS cells. Results: The most striking finding was that Δ5-Adiol had greater stimulatory effect than DHEA on rat osteoblast proliferation and differentiation, as well as ALPL expression in human osteoblasts. Interestingly, the Δ5-Adiol or DHEA-induced effects were not precluded with letrozole or trilostane, consistent with bioconversion of DHEA to Δ5-Adiol due to elevated expression of Hsd17b1 in neonatal rat osteoblasts, suggesting a high level of 17ß-hydroxysteroid dehydrogenase type 1 activity. Conversely, Δ5-Adiol and DHEA-induced proliferative effects were inhibited with ICI 182780 alone or combined with trilostane, which correlates with the higher binding affinity of Δ5-Adiol for ER compared to DHEA. Furthermore, Δ5-Adiol showed a greater relative agonist activity for hERα than for hERß or hAR. Conclusion: This study is the first to show that a bioactive DHEA derivative stimulates E2-dependent osteoblast activities, including proliferation and differentiation in rat and human osteoblasts, through ERα-related mechanisms.

Potential neuroprotective effect of androst-5-ene-3ß, 17ß-diol (ADIOL) on the striatum, and substantia nigra in Parkinson's disease rat model.

Parkinson's disease (PD) is a progressive neurodegenerative disorder with behavioral and motor abnormalities. Androst-5-ene-3ß, 17ß-diol (ADIOL), an estrogen receptor (ER) ß agonist, was found to mediate a transrepressive mechanism that selectively modulates the extent of neuroinflammation and, in turn, neurodegeneration. In consensus, ERß polymorphism was more frequently detected in early-onset PD patients. Thus, in an approach to elucidate the role of ERß agonists on PD, our study was designed to investigate the possible neuroprotective effect of ADIOL, in three dose levels (0.35, 3.5, 35 mg/kg/day), against rotenone (ROT)-induced PD rat model. Amelioration in striatal dopamine (DA), nuclear factor-kappa B (NF-κB), and the expression of down-stream inflammatory mediators, as well as apoptotic markers were observed in the striatum and substantia nigra (SN) upon pre-treatment with the three doses of ADIOL. Similarly, light microscopy (LM) examination revealed declined degeneration of neurons upon pretreatment with ADIOL. Significant improvement in nigral tyrosine hydroxylase (TH) and reduction of nigral α-synuclein densities were also detected after ADIOL pre-treatment with better results frequently achieved with the middle dose (3.5 mg/kg/day). The middle dose of ADIOL showed behavioral improvement, with elevation in the ATP level, which was emphasized by the improvement in mitochondrial integrity observed upon electron microscopy (EM) examination. In conclusion, the present study confirmed for the first time the ability of ADIOL to protect against neuroinflammation and, in turn, neurodegeneration process and motor dysfunction in PD animal model, which was more obviously observed with the middle dose.

The promyelinating properties of androstenediol in gliotoxin-induced demyelination in rat corpus callosum.

AIMS: Experimental evidence has shown that the adrenal steroid hormone, androstenediol, dampens the symptoms of demyelination. However, the cellular and molecular effects of androstenediol are not yet known. In the present study, we investigated the cellular and subcellular effects of this hormone in a gliotoxin-induced demyelination model. METHODS: Male Sprague Dawley rats received 2 µl of either saline or the gliotoxin ethidium bromide (EB, 0.04%) into the corpus callosum. These rats received daily subcutaneous injections of either oil or androstenediol (5 mg/kg). Their brains were collected at 2, 7, 14 and 28 days post-EB injection. Demyelinated lesions were assessed using Luxol fast blue staining. Immunofluorescent staining was used to investigate the number of oligodendrocyte progenitor cells, their maturation and microglial activation at the lesion site. Remyelination was further explored using transmission electron microscopy. The expression levels of total and phosphorylated MBP isoforms and CNPase were explored using western blot. RESULTS: Androstenediol decreased the size of demyelinated lesions in the corpus callosum at 7 and 14 days post-EB injection. It enhanced the number of oligodendrocyte precursor cells, promoted an increase in the number of mature oligodendrocytes and reduced microglial activation. Androstenediol also stimulated the phosphorylation of MBP at the site of the lesion and promoted remyelination of the affected axons. CONCLUSIONS: These data strongly suggest that androstenediol is endowed with promyelinating properties in a model of focal gliotoxin-induced demyelination. It induces its promyelinating effects by enhancing the number of oligodendrocyte precursor cells and their maturation at the lesion site.

Effects of CYP7B1-related steroids on androgen receptor activation in different cell lines.

The widely expressed steroid hydroxylase CYP7B1 is involved in metabolism of a number of steroids reported to influence estrogen and androgen signaling. Several studies by us and other investigators have linked this enzyme to effects on estrogen receptor activation. In a previous report we examined the effect of CYP7B1-mediated hormone metabolism for estrogen-mediated response in kidney-derived HEK293 cells. In the current study we used an androgen response element (ARE) reporter system to examine androgen-dependent response of some CYP7B1 substrates and CYP7B1-formed metabolites in several cell lines derived from different tissues. The results indicate significantly lower androgen receptor activation by CYP7B1-formed steroid metabolites than by the corresponding steroid substrates, suggesting that CYP7B1-mediated catalysis may decrease some androgenic responses. Thus, CYP7B1-dependent metabolism may be of importance not only for estrogenic signaling but also for androgenic. This finding, that CYP7B1 activity may be a regulator of androgenic signaling by converting AR ligands into less active metabolites, is also supported by real-time RT-PCR experiment where a CYP7B1 substrate, but not the corresponding product, was able to stimulate known androgen-sensitive genes. Furthermore, our data indicate that the effects of some steroids on hormone response element reporter systems are cell line-specific. For instance, despite transfection of the same reporter systems, 5-androstene-3ß,17ß-diol strongly activates an androgen-dependent response element in prostate cancer cells whereas it elicits only ER-dependent responses in kidney HEK293 cells. Potential roles of cell-specific metabolism or comodulator expression for the observed differences are discussed.

The protective and therapeutic effects of 5-androstene3ß, 17ß-diol (ADIOL) in abdominal post-operative adhesions in rat: Suppressing TLR4/NFκB/HMGB1/TGF1 ß/α SMA pathway.

Neurosteroid, 5-androstenediol (ADIOL) had been experimentally applied to protect against many diseases as it had anti-oxidant, anti-inflammatory, and anti-apoptotic effects. In our study, we investigate its role in abdominal postoperative adhesion (APA) formations. Our results demonstrate that ADIOL alleviates APA formation after induction by cecal abrasion (CA) model in the male rat. Interestingly, per administration of ADIOL before APA induction leads to inhibit oxidative stress by increasing superoxide dismutase (SOD) and decreasing Malondialdehyde (MAD) levels to a similar level to the sham group, in addition inhibiting inflammatory pathway by decreasing toll-like receptor 4 (TLR4), nuclear factor kappa-B (NFκB), and High mobility group box 1 (HMGB1) to a similar level to the sham group, furthermore decreasing Transforming growth factor beta 1 (TGFß1) and alpha Smooth muscle -actin (α SMA) levels to similar levels in the sham group. While administration of ADIOL after APA induction lead to decrease adhesions formation by decreasing oxidative stress (↓MDA and ↑SOD levels), inflammatory markers (↓TLR4, ↓NFκB, and ↓HMGB1levels), and collagen deposition by (↓TGF1 ß and↓α SMA levels) is the highly significant manner to those levels in CA model but also significant to those levels in the sham group. Concluded that, pre-administration of ADIOL before APA induction was more effective than its administration after adhesions formations.

Comparison of the effects of dietary protein, androstenediol and forearm muscle area on radial bone variables in healthy prepubertal children.

Adequate dietary habits are supposed to be one of the most important modifiable factors in osteoporosis prevention. However, the importance of specific nutrients is controversial. We examined relevant nutrients which are supposed to have an impact on bone parameters and compared their effect sizes with those of two known predictors of bone development: bone-related muscle mass and androgen levels. We analysed nutritional, hormonal and anthropometric data from 107 prepubertal children participating in the Dortmund Nutritional and Anthropometric Longitudinally Designed Study. Diaphyseal bone mineral content (BMC), cortical area (CA), periosteal circumference, strength strain index and muscle area of the non-dominant forearm were measured by peripheral quantitative computed tomography. Data on long-term nutrient intakes (e.g. protein, Ca and vitamin D) were derived from 3 d weighed dietary records. Twenty-four hour urinary excretion rates of androgen metabolites including the sex steroid androstenediol were measured using GC-MS. Of all considered nutrients, only protein showed a trend for an association with BMC (ß = +0·11; P = 0·073) and CA (ß = +0·11; P = 0·056) in stepwise linear regression models. None of the other considered dietary variables was associated with bone parameters. The size of the bone anabolic effect of protein was partly comparable with that of androstenediol. Even though boys gained more bone mass in comparison with girls, the protein effect did not differ between sexes. Bone-related muscle area and sex steroids have the strongest effects on prepubertal diaphyseal bone. However, dietary protein may have a similar bone anabolic influence compared with androstenediol. In children without explicit nutrient deficits, protein seems to be the most important dietary component for diaphyseal bone status.

Hydroxylation of DHEA, androstenediol and epiandrosterone by Mortierella isabellina AM212. Evidence indicating that both constitutive and inducible hydroxylases catalyze 7α- as well as 7ß-hydroxylations of 5-ene substrates.

The course of transformation of DHEA, androstenediol and epiandrosterone in Mortierella isabellina AM212 culture was investigated. The mentioned substrates underwent effective hydroxylation; 5-ene substrates--DHEA and androstenediol--were transformed into a mixture of 7α- and 7ß- allyl alcohols, while epiandrosterone was converted into 7α- (mainly), 11α- and 9α- monohydroxy derivatives. Ketoconazole and cycloheximide inhibition studies suggest the presence of constitutive and substrate-induced hydroxylases in M. isabellina. On the basis of time course analysis of the hydroxylation of DHEA and androstenediol, the oxidation of allyl C(7)-H(α) and C(7)-H(ß) bonds by the same enzyme is a reasonable assumption.

5-Androstenediol prevents radiation injury in mice by promoting NF-κB signaling and inhibiting AIM2 inflammasome activation.

In the present study, the therapeutic effects of 5-androstenediol on radiation-induced myeloid suppression and tissue damage in mice and the possible mechanism were explored. The mice were subjected to whole-body irradiation, and 5-androstenediol was administered subcutaneously at different times and doses. The evaluation of the survival rate showed that the administration of 5-androstenediol every three days post-irradiation was the most effective in decreasing the death of the mice. Additionally, 5-androstenediol dose-dependently reduced the death caused by 9 Gy radiation. The pharmacological mechanism was investigated by blood analysis, western blot analysis, immunofluorescence and immunohistochemistry. 5-Androstenediol significantly ameliorated myeloid suppression, as demonstrated by elevated levels of total white blood cells, including neutrophils and platelets, in the peripheral blood. By H&E staining, we found that radiation-induced myeloid suppression in the bone marrow and spleen, as well as tissue damage in the lung and colon, was significantly ameliorated by treatment with 5-androstenediol. Immunohistochemistry showed elevated phosphorylation of p65 in the bone marrow and spleen, indicating the activation of NF-κB signaling. Moreover, 5-androstenediol markedly hampered the radiation-induced activation of caspase-1 and GSDMD in the colon by decreasing the interaction between AIM2 and ASC. Taken together, our results suggest that, by promoting NF-κB signaling and inhibiting inflammasome-mediated pyroptosis, 5-androstenediol can be used as a radioprotective drug.

Inhibition of androstenediol-dependent LNCaP tumour growth by 17alpha-ethynyl-5alpha-androstane-3alpha, 17beta-diol (HE3235).

Androst-5-ene-3beta, 17beta-diol (AED) is an adrenal hormone that has been reported to sustain prostate cancer growth after androgen deprivation therapy (ADT). LNCaP cells express a mutated androgen receptor that confers the ability to respond not only to androgen but also to oestrogen and adrenal hormones such as AED, and thus provide a cell line useful for identifying compounds capable of inhibiting AED-stimulated cell growth. We sought to determine whether structurally related steroids could inhibit AED-stimulated LNCaP cell growth in vitro and tumour growth in vivo. We report here the identification of a novel androstane steroid, HE3235 (17alpha-ethynyl-5alpha-androstan-3alpha, 17beta-diol), with significant inhibitory activity for AED-stimulated LNCaP proliferation. This inhibitory activity is accompanied by an increase in the number of apoptotic cells. Animal studies have confirmed the cytoreductive activity of HE3235 on LNCaP tumours. The results suggest that this compound may be of clinical use in castration-resistant prostate cancer.

Androstenediol reverses steroid-inhibited wound healing.

It is well recognized that stress of any nature will cause a delay in the wound healing response. This delayed healing response appears closely associated with immune regulators. In this study, CD-1 mice were injected with a long acting form of methyl prednisolone to cause a steroid-induced immune suppression. After 24 hours, two 6-mm full thickness wounds were placed on the animals' backs and one group of animals received the immune-regulating hormone, androstenediol. Wound contraction was quantified by planimetry for the subsequent 14 days. Animals that were stressed with methyl prednisolone but receiving androstenediol contracted their open wounds at faster rates compared with methyl prednisolone-stressed animals treated with the vehicle alone. These findings suggest that restoration of immune regulation by androstenediol can reverse the delayed open wound contraction secondary to steroid stress.

Brain microglia express steroid-converting enzymes in the mouse.

In the CNS, steroid hormones play a major role in the maintenance of brain homeostasis and it's response to injury. Since activated microglia are the pivotal immune cell involved in neurodegeneration, we investigated the possibility that microglia provide a discrete source for the metabolism of active steroid hormones. Using RT-PCR, our results showed that mouse microglia expressed mRNA for 17beta-hydroxysteroid dehydrogenase type 1 and steroid 5alpha-reductase type 1, which are involved in the metabolism of androgens and estrogens. Microglia also expressed the peripheral benzodiazepine receptor and steroid acute regulatory protein; however, the enzymes required for de novo formation of progesterone and DHEA from cholesterol were not expressed. To test the function of these enzymes, primary microglia cultures were incubated with steroid precursors, DHEA and AD. Microglia preferentially produced delta-5 androgens (Adiol) from DHEA and 5alpha-reduced androgens from AD. Adiol behaved as an effective estrogen receptor agonist in neuronal cells. Activation of microglia with pro-inflammatory factors, LPS and INFgamma did not affect the enzymatic properties of these proteins. However, PBR ligands reduced TNFalpha production signifying an immunomodulatory role for PBR. Collectively, our results suggest that microglia utilize steroid-converting enzymes and related proteins to influence inflammation and neurodegeneration within microenvironments of the brain.

Dehydroepiandrosterone up-regulates the Adrenoleukodystrophy-related gene (ABCD2) independently of PPARalpha in rodents.

X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disease caused by mutations in the ABCD1 gene, which encodes a peroxisomal ABC transporter, ALDP, supposed to participate in the transport of very long chain fatty acids (VLCFA). The adrenoleukodystrophy-related protein (ALDRP), which is encoded by the ABCD2 gene, is the closest homolog of ALDP and is considered as a potential therapeutic target since functional redundancy has been demonstrated between the two proteins. Pharmacological induction of Abcd2 by fibrates through the activation of PPARalpha has been demonstrated in rodent liver. DHEA, the most abundant steroid in human, is described as a PPARalpha activator and also as a prohormone able to mediate induction of several genes. Here, we explored the in vitro and in vivo effects of DHEA on the expression of peroxisomal ABC transporters. We show that Abcd2 and Abcd3 but not Abcd4 are induced in primary culture of rat hepatocytes by DHEA-S. We also demonstrate that Abcd2 and Abcd3 but not Abcd4 are inducible by an 11-day treatment with DHEA in the liver of male rodents but not in brain, testes and adrenals. Finally and contrary to Abcd3, we show that the mechanism of induction of Abcd2 is independent of PPARalpha.

5-androstenediol improves survival in clinically unsupported rhesus monkeys with radiation-induced myelosuppression.

We previously reported that five daily intramuscular doses of 5-androstenediol (AED), a naturally occurring adrenal steroid hormone, stimulated multilineage recovery of bone marrow in rhesus monkeys with radiation-induced myelosuppression after 4.0 Gy total body irradiation (TBI). Here we report the effect of AED on the survival of eighty rhesus macaques that received a 6.0 Gy dose of TBI in four sequential pilot studies. The drug was administered intramuscularly, based on body weight, 2-4 h after irradiation and continued once daily for a total of five injections. No clinical support in the form of antibiotics or transfusions was given to the animals at any time during the study. Five of the 40 (12.5%) treated animals died, compared to 13 of 40 (32.5%) of the animals in the control group (p=0.032). The combination of accumulated days of thrombocytopenia (<20,000 platelets/microL) up to day 14 (before the first death) together with treatment, accurately predicts mortality (p<0.001). The compound significantly reduced the duration of thrombocytopenia and neutropenia (p<0.01). The accumulation of days of neutropenia (ANC<500 cells/microL) up to day 14 plays no major role in predicting death. AED shows significant activity in irradiated primates with acute hematopoietic radiation syndrome.

Protective Effects of Fetal Zone Steroids Are Comparable to Estradiol in Hyperoxia-Induced Cell Death of Immature Glia.

Impaired neurodevelopment in preterm infants is caused by prematurity itself; however, hypoxia/ischemia, inflammation, and hyperoxia contribute to the extent of impairment. Because preterm birth is accompanied by a dramatic decrease in 17ß-estradiol (E2) and progesterone, preliminary clinical studies have been carried out to substitute these steroids in preterm infants; however, they failed to confirm significantly improved neurologic outcomes. We therefore hypothesized that the persistently high postnatal production of fetal zone steroids [mainly dehydroepiandrosterone (DHEA)] until term could interfere with E2-mediated protection. We investigated whether E2 could reduce hyperoxia-mediated apoptosis in three immature glial cell types and detected the involved receptors. Thereafter, we investigated protection by the fetal zone steroids DHEA, 16α-hydroxy-DHEA, and androstenediol. For DHEA, the involved receptors were evaluated. We examined aromatases, which convert fetal zone steroids into more estrogenic compounds. Finally, cotreatment was compared against single hormone treatment to investigate synergism. In all cell types, E2 and fetal zone steroids resulted in significant dose-dependent protection, whereas the mediating receptors differed. The neuroprotection by fetal zone steroids highly depended on the cell type-specific expression of aromatases, the receptor repertoire, and the potency of the fetal zone steroids toward these receptors. No synergism in fetal zone steroid and E2 cotreatment was detected in two of three cell types. Therefore, E2 supplementation may not be beneficial with respect to neuroprotection because fetal zone steroids circulate in persistently high concentrations until term in preterm infants. Hence, a refined experimental model for preterm infants is required to investigate potential treatments.

Molecular Mechanisms of Androstenediol in the Regulation of the Proliferative Process of Human Endometrial Cells.

Proliferation in endometria of women with polycystic ovarian syndrome (PCOS) is increased, similar to the biosynthesis of androstenediol (estrogenic metabolite). As previously shown, in human endometrial cells, androstenediol increases CYCLIN D1 levels and KI67 and decreases P27 content. The objective of the present investigation was to determine the mechanisms by which androstenediol promotes endometrial cell-cycle progression. Estrogen receptor α (ERα) activation and changes in CYCLIN D1 and P27 levels were evaluated by Western blot in T-HESC and St-T1b endometrial cell lines, using receptor antagonists; activation of PI3K-protein kinase B (AKT) and mitogen-activated protein kinases-extracellular signal-regulated kinases (MAPK-ERK)1/2 pathways was evaluated using PI3K, MAPK/ERK kinase (MEK)1/2, and RNA-polymerase II inhibitors. The data showed that androstenediol treatment significantly increases CYCLIN D1 and decreases P27 levels through ERα activation ( P < .05). In addition, an increase in AKT/ERK1/2 phosphorylations was determined ( P < .05). In the presence of RNA-polymerase II inhibitor, phosphorylation of AKT/ERK1/2 decreased ( P < .05), meaning that endometrial cells need transcriptional activity to activate the kinases involved. It was also observed that PI3K action is required for P27 and CYCLIN D1 changes. Therefore, the action of androstenediol in endometria depends on PI3K-AKT and MAPK-ERK1/2 pathways activation, together with cell transcriptional machinery. This could be of clinical significance, as in pathologies such as PCOS, increased endometrial levels of androstenediol together with a high prevalence of endometrial hyperplasia and adenocarcinoma have been reported.

5-androstenediol stimulates multilineage hematopoiesis in rhesus monkeys with radiation-induced myelosuppression.

Total body ionizing irradiation (TBI) between 2-8 Gy causes the hematopoietic component of the acute radiation syndrome (ARS) in humans. Here we report on an exploratory study with 5-androstenediol (AED) in rhesus monkeys exposed to 4 Gy (60)Co gamma TBI. In this study, the effects of two formulations administered 3-4 h after irradiation were evaluated. After radiation, severe neutropenia (<500 neutrophils/microL), thrombocytopenia (<50,000 platelets/microL), and anemia (hemoglobin <8.0 g/dL) occurred in 6, 6, and 5 of the 6 control animals, respectively. In these 6 control animals, the median time to first day of each defined cytopenia was 8.5, 13, and 20 days and the median time to last occurrence was 22.5, 19.5 and 29.5 days, respectively. All treated groups had a decrease in the duration of severe neutropenia relative to vehicle control. All but one dosing regimen decreased the duration of thrombocytopenia and anemia. Five consecutive days of a 15 mg/kg intramuscular (IM) micro-particle preparation and a once weekly 15 mg/kg subcutaneous (SC) nanoparticle suspension generally provided the greatest radiation protection. AED, as a single agent, promotes multilineage hematopoietic recovery of the bone marrow. These data suggest that it may play an important therapeutic role in the management of acute radiation syndrome.

Induction of microsomal and peroxisomal enzymes by dehydroepiandrosterone and its reduced metabolite in rats.

Dehydroepiandrosterone (DHEA) given to rodents in pharmacological doses induces several hepatic enzymes including cytochromes P4504A, NADPH:P450 oxidoreductase, palmitoyl coenzyme A oxidase, and other enzymes associated with the peroxisomal beta-oxidation pathway, leading to peroxisome proliferation and development of hepatocellular carcinoma in rodents. Comparison of the inductive potency of DHEA and other intermediates of the steroid biosynthetic path demonstrated that only DHEA, 5-ene-androstene-3 beta,17 beta-diol (ADIOL), and to a lesser extent, 17 alpha-hydroxypregnenolone, a precursor of DHEA, induce cytochromes P4504A protein and other enzymes associated with the peroxisome proliferative response in vivo. ADIOL exerted its inductive response at a somewhat lower dosage than DHEA, whereas ADIOL and DHEA both induced the microsomal enzymes (P4504A and its oxidoreductase) at somewhat lower dosages than those required to induce peroxisomal enzymes. Northern analysis demonstrated increases in the mRNAs encoding the cytochromes P4504A (> 20-fold) and NADPH:P450 oxidoreductase (> 10-fold) in the livers of DHEA- and ADIOL-treated rats. Run-on transcription analysis demonstrated that DHEA induces CYP4A gene expression 11-fold at the level of transcription initiation. Comparison of the responsiveness of individual rat CYP4A genes (4A1, 4A2, and 4A3) to DHEA and ADIOL in immature versus mature male rats revealed 2-3-fold higher levels of induced CYP4A1 and 4A3 mRNAs in immature rat livers. In contrast, hepatic CYP4A2 mRNA was induced to 6-10-fold higher levels in mature rats. No basal or significant inducible expression of mRNA for CYP4A1 and 4A3 was noted in rat kidney. Significant basal levels of kidney CYP4A2 mRNA were observed only in mature animals, where they were inducible by ADIOL and DHEA to a 3-5-fold greater extent than in the kidneys of immature rats. These studies demonstrate developmental differences in the responsiveness of CYP4A mRNA levels to DHEA and ADIOL in rat kidney and liver. Moreover, the striking inducibility of CYP4A protein and mRNAs, together with the increased rates of synthesis of nascent CYP4A mRNA transcripts in hepatic nuclei from DHEA-treated rats, establish that DHEA increases the expression of these microsomal enzymes at the transcriptional level.

Estrogenic effects of physiological concentrations of 5-androstene-3 beta, 17 beta-diol and its metabolism in MCF7 human breast cancer cells.

5-Androstene-3 beta, 17 beta-diol (ADIOL) has previously been shown to have a high affinity for the estrogen receptor and to translocate it to the nucleus in vitro and in vivo. This compound and related C19 delta 5-steroids of adrenal origin have now been examined for their ability to induce the synthesis in MCF7 cells of an estrogen-dependent secreted glycoprotein (M.W. 46,000). Concentrations required for half-maximum induction were 2 nM for ADIOL and 500 nM for dehydroepiandrosterone (DHEA). Dehydroepiandrosterone sulfate showed weak inducing ability at concentrations of 1 microM or greater. The induction by ADIOL was unaffected by the presence of an aromatase inhibitor, and 5 alpha-androstane-3 beta, 17 beta-diol, which cannot be aromatized, also induced the M.W. 46,000 protein at low concentrations. When cells were exposed to 10 nM [3H]ADIOL, the cytosol and nuclear fractions contained [3H]ADIOL resistant to charcoal adsorption. The bound [3H]ADIOL in the cytosol and nucleus was displaceable by 17 beta-estradiol and tamoxifen, suggesting that it was binding to the estrogen receptor. [3H]ADIOL was metabolized to its 3 beta-sulfate, which was excreted into the medium, and to [3H]DHEA, which was found in the cells and the medium as free DHEA and its 3 beta-sulfate. [3H]DHEA was also metabolized by the cells to its 3 beta-sulfate, to free ADIOL, and to the 3 beta-sulfate of adiol. We conclude that: (a) ADIOL is effective as an estrogen in MCF7 cells at a concentration of 2 nM, which is within the range found in the blood of normal women; and (b) sulfurylation is a major route of inactivation of 3 beta-hydroxy delta 5-steroids in MCF7 cells.

Stimulation of cell proliferation and estrogenic response by adrenal C19-delta 5-steroids in the ZR-75-1 human breast cancer cell line.

We have examined the effect of androst-5-ene-3 beta,17 beta-diol (delta 5-diol) and its precursors, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone 3 beta-sulfate (DHEAS), on the growth of the estrogen-sensitive human breast cancer cell line, ZR-75-1. While the cell number was increased up to 4-fold by maximal concentrations of estradiol, delta 5-diol maximally stimulated cell proliferation by approximately 3-fold. Since the half-maximal stimulation achieved by delta 5-diol is observed at 2.5 nM and the normal range of plasma concentrations of this steroid in women is 1 to 3 nM, it is most likely that the stimulatory effect of delta 5-diol has physiological significance. DHEA and DHEAS were much less effective than delta 5-diol in stimulating the proliferation of ZR-75-1 cells, the maximal effect on cell number being 75% at the maximal dose used, namely 10 microM. The mitogenic effects of estradiol and delta 5-diol were competitively inhibited by the antiestrogen LY156758 (keoxifene), while the effects of DHEA and DHEAS were completely abolished by the antiestrogen. The effects of DHEA and delta 5-diol on cell proliferation are not likely to be mediated via their conversion to estrone or estradiol, since androstenedione had no effect, while testosterone and dihydrotestosterone decreased cell number by about 20%. The number of specific progesterone binding sites was increased 3.7-, 3.2-, and 2.0-fold by delta 5-diol, DHEA, and DHEAS, respectively. The relative potency of the C19-delta 5-steroids to increase the number of progesterone-specific binding sites was comparable to their ability to stimulate cell proliferation. Direct competition experiments performed with intact cells in monolayer culture showed that, under conditions of minimal metabolism, only delta 5-diol could significantly compete with estradiol for cellular estrogen-specific binding sites with an apparent dissociation constant of 11 nM, thus suggesting that physiological concentrations of C19-delta 5-steroids of adrenal origin could exert an estrogenic stimulation of breast tumor growth without involvement of the aromatase pathway. The present data suggest not only that estrone derived from androstenedione could play a role in estrogen-sensitive breast cancer in women but that delta 5-diol could well be the most important estrogen in breast cancer in women.

Adrenal androgens stimulate the proliferation of breast cancer cells as direct activators of estrogen receptor alpha.

Estrogens stimulate the proliferation of many breast tumors and cell lines derived from them. Antiestrogens have therefore become a powerful therapeutic agent to treat breast tumors that express estrogen receptor (ER) alpha. In addition, aromatase inhibitors are now used in postmenopausal women to block the in situ conversion of adrenal androgens to estrogens. This approach can only be successful if ER-alpha in a particular tumor is not directly stimulated by adrenal androgens. We have examined this possibility using several different cell lines as model systems: (a) wild-type MCF7 cells, an ER-alpha-dependent human breast cancer cell line; (b) MCF7SH cells, an estrogen-independent MCF7 variant; (c) Ishikawa cells, an ER-alpha-containing human uterine cell line; (d) ER-negative HeLa cells; and (e) budding yeast. Transactivation assays with transfected ER-alpha reporter genes reveal a direct activation of ER-alpha by dehydroepiandrosterone (DHEA), 5alpha-androstene-3beta,17beta-diol, testosterone, and the two nonaromatizable androgens, dihydrotestosterone and 5alpha-androstane-3beta,17beta-diol. The involvement of other steroid receptors could be ruled out with specific antihormones. Moreover, the same set of ligands stimulates the proliferation of the two breast cancer cell lines. At subsaturating and physiologically relevant concentrations of DHEA, DHEA stimulates the proliferation of MCF7SH cells, which correlates with a substantial, albeit submaximal, transcriptional response. Thus, adrenal androgens must also be considered as risk factors in postmenopausal women.