Comparative study of plasma steroid and steroid glucuronide levels in normal men and in men with benign prostatic hyperplasia

Plasma steroids were analyzed in 16 normal men and in 10 men with prostatic benign hyperplasia (BPH). The steroids measured by radioimmunoassay include pregnenolone, 17-OH-pregnenolone, dehydroepiandrosterone, androst-5-ene-3 beta, 17 beta-diol, testosterone, dihydrotestosterone, androstane-3 alpha, 17 beta-diol, androstane-3 beta, 17 beta-diol, estrone, and estradiol as well as their glucuronide derivatives. In addition, cortisol and the sulphoconjugated form of dehydroepiandrosterone were determined. Whereas the levels of pregnenolone, pregnenolone glucuronide and 17-OH-pregnenolone glucuronide are not different in the two groups, the levels of 17-OH-pregnenolone in the BPH group (0.87 +/- 0.07 ng/ml) exceed by two-fold (p less than 0.01) those observed in normal men. Plasma dehydroepiandrosterone and androst-5-ene-3 beta, 17 beta-diol concentrations are markedly elevated in the BPH group (1.49 +/- 0.23 and 0.55 +/- 0.08 ng/ml vs the control groups 0.43 +/- 0.11 and 0.31 +/- 0.05 ng/ml, respectively). Since the plasma cortisol and pregnenolone levels are comparable in these two groups, our data suggest that the elevation of plasma 17-OH-pregnenolone, dehydroepiandrosterone, and androst-5-ene-3 beta, 17 beta-diol reflects an increase of adrenal 17-hydroxylase activity in patients with BPH. A slight increase of the plasma dihydrotestosterone and androsterone glucuronide concentration is also observed in men with BPH, indicating an increase of 5 alpha-reduced androgen formation. We have also observed, in the BPH group, a 50% decrease (p less than 0.01) of plasma glucuronidated androst-5-ene-3 beta, 17 beta-diol, estrone, and estradiol levels, suggesting that the transformation of unconjugated estrogenic steroids into glucuronide derivative is inhibited in BPH patients. In summary, our data indicate that adrenal C-19 steroids might be involved in the process of BPH. Furthermore, whereas the estrogen glucuronide formation is diminished in men with BPH, the prostatic androgen metabolism as reflected by plasma dihydrotestosterone and androsterone glucuronide concentrations seems to be increased.     

Effect of MK-906, a specific 5 alpha-reductase inhibitor, on serum androgens and androgen conjugates in normal men

To determine the hormonal effects of MK-906, an orally active 5 alpha-reductase inhibitor, on serum androgens and androgen conjugates, 12 healthy men were given 10, 20, 50, and 100 mg MK-906 2 weeks apart in randomized order in a 4-period crossover design. Serum testosterone (T), dihydrotestosterone (DHT), androstanediol glucuronide, and androsterone glucuronide were measured before and 24 hours after each dose. The effect of MK-906 on glucuronyl transferase activity, the enzyme responsible for androstanediol glucuronide and androsterone glucuronide formation, was assessed in vitro using rat prostate tissue. Serum T levels were unchanged after all doses. Serum DHT, androstanediol glucuronide, and androsterone glucuronide were suppressed by 70, 40, and 56%, respectively, after the 10-mg dose, and by 82, 52, and 66% after the 100-mg dose (P less than 0.02 for the comparison between the 10 and 100-mg doses for all three steroids), respectively. Baseline serum T and DHT levels were strongly correlated (R = 0.89, P = 0.0002), as were androstanediol glucuronide and androsterone glucuronide levels (R = 0.78, P = 0.003), but there was no correlation between DHT levels and the levels of either conjugated steroid. MK-906 had no effect on glucuronyl transferase activity in vitro. It was concluded that single doses of MK-906 suppress both conjugated and unconjugated 5 alpha-reduced androgens. While all three steroids appeared to be good markers of systemic 5 alpha-reductase inhibition, further research will be needed to determine which steroid best reflects tissue DHT levels in patients receiving these inhibitors.     

Serum androgen bioactivity during 5alpha-dihydrotestosterone treatment in elderly men

The androgens used in the treatment of age-related androgen decline have different bioactivities that cannot be evaluated with conventional detection methods for serum steroids. We have recently developed a recombinant cell bioassay for the determination of androgen bioactivity in human serum that is based on androgen-specific interaction between the ligand-binding domain (LBD) and the N-terminal region of the androgen receptor (AR). In this work, we examined the effect of topically applied 5alpha-dihydrotestosterone (DHT; 7.5-10 g of 2.5% DHT gel daily for 6 months) on circulating androgen bioactivity in 14 men (age range, 51-63 years) with symptoms of andropause and pretreatment serum testosterone less than 15 nM, or serum sex hormone-binding globulin concentration greater than 30 nM, or both. The mean (+/-SEM) pretreatment androgen bioactivity was 3.3 +/- 0.3 nM testosterone equivalents, and the levels correlated with serum testosterone concentration (r =.55, P <.05). DHT gel treatment induced a sixfold increase (from 1.5 +/- 0.1 nM to 9.0 +/- 0.7 nM) in mean serum DHT level, whereas endogenous testosterone and estradiol levels measured with radioimmunoassays were suppressed by approximately 70% and approximately 50%, respectively (P <.0001). Concomitantly, serum androgen bioactivity increased by sevenfold (from 3.3 +/- 0.3 to 23.6 +/- 2.8 nM testosterone equivalents; P <.0001). We conclude that DHT gel therapy in elderly men significantly increases their circulating androgen bioactivity as measured with a mammalian cell bioassay. An androgen-specific bioassay such as ours may enable investigation of other androgens with different bioactivities, such as selective AR modulators.     

A phase II study of mifepristone (RU-486) in castration-resistant prostate cancer, with a correlative assessment of androgen-related hormones

OBJECTIVE

To evaluate mifepristone (RU‐486) in patients with castration‐resistant prostate cancer (CRPC), with a correlative assessment of serum androgens and androgen metabolites

PATIENTS AND METHODS

The androgen receptor (AR) is critical in the development and progression of prostate cancer, but available antiandrogens incompletely abrogate AR signalling. Mifepristone is a potent AR antagonist that functions by competing with androgen, preventing AR coactivator binding and by enhancing binding of AR corepressors. Patients with CRPC were treated with mifepristone 200 mg/day oral until disease progression. Testosterone, dihydrotestosterone (DHT), androstenedione, dihydroepiandrosterone sulphate and the testosterone metabolite 3α‐diol G, were measured at baseline and during therapy.

RESULTS

Nineteen patients were enrolled between April and August 2005; they were treated for a median (range) of 85 (31–338) days. The median prostate‐specific antigen (PSA) level at enrolment was 22.0 (3.0–937.2) ng/mL. No patient had a PSA response (>50% reduction in PSA). Six patients had stable disease for a median of 5.5 months. After 1 month, adrenal androgens were increased and testosterone and DHT increased by 91% and 80%, respectively, compared to baseline.

CONCLUSION

Mifepristone had limited activity in patients with CRPC, and stimulated a marked increase in adrenal androgens, testosterone and DHT. We hypothesise that inhibition of glucocorticoid receptor by mifepristone resulted in an increase in adrenocorticotropic hormone and subsequent increase in adrenal androgens, and that their conversion by tumour cells to testosterone and DHT probably limited the efficacy of mifepristone. These data emphasize the continued importance of alternative androgen sources in AR signalling in CRPC.     

Androgens have antiresorptive effects on trabecular disuse osteopenia independent from muscle atrophy

Aging hypogonadal men are at increased risk of osteoporosis and sarcopenia. Testosterone is a potentially appealing strategy to prevent simultaneous bone and muscle loss. The androgen receptor (AR) mediates antiresorptive effects on trabecular bone via osteoblast-lineage cells, as well as muscle-anabolic actions. Sex steroids also modify the skeletal response to mechanical loading. However, it is unclear whether the effects of androgens on bone remain effective independent of mechanical stimulation or rather require indirect androgen effects via muscle. This study aims to characterize the effects and underlying mechanisms of androgens on disuse osteosarcopenia. Adult male mice received a unilateral botulinum toxin (BTx) injection, and underwent sham surgery or orchidectomy (ORX) without or with testosterone (ORX + T) or dihydrotestosterone (ORX + DHT) replacement. Compared to the contralateral internal control hindlimb, acute trabecular number and bone volume loss was increased by ORX and partially prevented DHT. T was more efficient and increased BV/TV in both hindlimbs over sham values, although it did not reduce the detrimental effect of BTx. Both androgens and BTx regulated trabecular osteoclast surface as well as tartrate-resistant acid phosphatase expression. Androgens also prevented BTx-induced body weight loss but did not significantly influence paralysis or muscle atrophy. BTx and ORX both reduced cortical thickness via endosteal expansion, which was prevented by T but not DHT. In long-term follow-up, the residual trabecular bone volume deficit in sham-BTx hindlimbs was prevented by DHT but T restored it more efficiently to pre-treatment levels. Conditional AR deletion in late osteoblasts and osteocytes or in the satellite cell lineage increased age-related trabecular bone loss in both hindlimbs without influencing the effect of BTx on trabecular osteopenia. We conclude that androgens have antiresorptive effects on trabecular disuse osteopenia which do not require AR actions on bone via muscle or via osteocytes.     

Fast Facts: Prostate Cancer

OBJECTIVE

To characterize the changes in androgen levels in the prostate after castration, as androgens are critical in the progression of prostate cancer after castration, but the time at which the androgen remaining in the prostatic cancer tissue after castration exerts its effects is poorly understood.

MATERIALS AND METHODS

The ventral prostate (VP) in adult male spontaneously hypertensive rats was excised at 2, 4 and 8 h, 1, 2, 4 and 7 days, and 2, 4 and 8 weeks after castration. The dihydrotestosterone (DHT), testosterone, dehydroepiandrosterone (DHEA) and androstenedione (4‐dione) levels in the VP were measured simultaneously using gas chromatography/tandem mass spectrometry.

RESULTS

Within 2 days of castration, the DHT and testosterone levels in the VP decreased sharply, while there were no significant changes in the DHEA or 4‐dione levels. From 2 days to 2 weeks after castration (2–7 days for 4‐dione), there was a sharp peak in tissue androgen levels in the VP (P < 0.05 for all androgens); during the subsequent 6 weeks after castration, all of the tissue DHT, testosterone, DHEA and 4‐dione levels gradually increased with time.

CONCLUSIONS

These data show the changes which occur in androgen levels in rat VP after castration and support the concept that the adrenal glands compensate for the loss of testicular androgen.     

Nongenomic androgen activation of phosphatidylinositol 3-kinase/Akt signaling pathway in MC3T3-E1 osteoblasts.

Androgens have important effects on the bone metabolism. However, the effect and mechanism of androgen action on the osteoblasts remains unknown. Here we showed that androgens increase phosphorylation and nuclear translocation of Akt. siRNA-AR prevented androgen-induced Akt activation in MC3T3-E1 cells. This suggests that nongenomic androgen activation of Akt is mediated by androgen receptor in osteoblasts. INTRODUCTION: Androgens have important effects on the human skeleton in both males and females. However, the mechanism of androgen action on bone metabolism remains unknown. The aims of this study were to determine the effect and mechanism of androgen action on the osteoblast cells. MATERIALS AND METHODS: Here we showed that 5alpha-dihydrotestosterone (DHT) accelerates cell growth of the MC3T3-E1 cell line in a time- and dose-dependent manner. The specific phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor LY294002 and kinase-deficient Akt mutant can repress the androgen effect on MC3T3-E1 cells. Western blot analysis showed that DHT, 17beta-estradiol, and testosterone (T) induce a rapid and transient phosphorylation of Akt in MC3T3-E1 cells. This activation reached to a plateau after 15 minutes and gradually diminished after 60 minutes of DHT treatment. RESULTS: Fluorescence microscopy showed a distinct increase in immunostaining intensity in the nuclear interior after androgen treatment but no change in the subcellular distribution of Akt when the cells were pretreated with hydroxyflutamide (HF) or LY294002. In addition, small interfering RNA against androgen receptor (siRNA-AR) prevented DHT-induced Akt phosphorylation and cell growth. CONCLUSION: These findings represents the first physiological finding to indicate how steroid hormones such as androgens can mediate the nuclear localization of Akt/PKB in osteoblasts that has previously mainly been linked to growth factor-induced events occurring at the plasma membrane level.     

Prostate tissue androgens: history and current clinical relevance

Direct determination of androgen levels in prostate tissue provides a perspective on the organ that is not available via androgen serum levels. The principle prostatic androgens, primarily dihydrotestosterone (DHT) and secondarily testosterone, can be readily assayed in quick-frozen prostate biopsy cores or surgical specimens. Such assays have proved important in establishing (1) that DHT is a permissive factor in BPH pathogenesis, (2) a mechanism for the treatment of BPH, (3) an understanding of prostate cancer chemoprevention, (4) an explanation for the 'escape' of prostate cancer from castration therapy, (5) prostate safety of testosterone replacement therapy, and (6) insights into the cause of racial differences of prostate cancer. Future opportunities include clarification of new drug mechanisms for BPH and prostate cancer, as well as a better understanding of the pathogenesis of both, and as an aid in individual patient management. Determination of prostate tissue androgens may soon transition from research tool to clinical test.     

Safety aspects of androgen treatment with 5alpha-dihydrotestosterone

5alpha-Dihydrotestosterone (DHT), the most powerful naturally occurring androgen, is commercially available since 1982 as a gel. In view of its considerably higher biopotency (three to six times) than of testosterone, side effects, particularly on the main target organ of androgens, the prostate, are anticipated. In fact, DHT appears to be a prostate-sparing androgen for two reasons. Unlike testosterone, it does not undergo any further amplification in biopotency through 5alpha reduction in the prostate. Secondly, it is likely to lead to less aromatisation of testosterone to oestradiol in the prostate, thus reducing local oestradiol concentrations. Oestrogens have been implicated in the aetiology of benign prostate hyperplasia and prostate cancer. However, aromatisation of testosterone has appeared to be essential for the maintenance of bone mineral density. Administration of DHT reduces circulating oestradiol levels, but the levels remain above the levels critical for the antiresorptive effect of oestrogens on bone. Effects of DHT on erythropoiesis and on lipids are very similar to those of testosterone. Safety concerns regarding androgen treatment with DHT are similar to those of treatment with testosterone, while the effects of DHT on the prostate are likely to be less biopotent.     

Intraprostatic testosterone and dihydrotestosterone. Part I: concentrations and methods of determination in men with benign prostatic hyperplasia and prostate cancer

Owing to inconsistencies and methodological differences, the present peer-reviewed literature lacks conclusive data on the intraprostatic levels of androgens, in particular dihydrotestosterone (DHT), in untreated benign prostatic hyperplasia (BPH) and prostate cancer. To date, no difference has been shown between DHT concentrations in normal prostatic tissue and BPH, and nor has a difference been shown in DHT concentrations between the histologically distinct regions of the prostate. Recent literature has also failed to show a consistent difference in androgen level between BPH and prostate cancer. The role of intraprostatic DHT in the pathogenesis of BPH and in the initiation and progression of prostate cancer thus remains to be established. Increased knowledge of the mechanisms of the androgenic steroid pathways in prostatic diseases, with a special focus on intraprostatic androgen levels may lead to more optimized and more personalized forms of treatment, and probably new therapeutic targets as well.     

【特刊综述】雄激素和前列腺疾病

越来越多的文献认同睾酮治疗在性腺机能低下患者中具有促合成代谢作用。而关于老年男性使用外源性雄激素的风险和其对前列腺潜在副作用的研究数据仍然匮乏。老年和性腺机能低下男性接受睾酮治疗是否会加重下尿路症状或加剧、揭露,甚至刺激前列腺癌发展,这一问题使采用睾酮治疗的热情有所减缓,与此同时前列腺疾病被视作睾酮治疗的相对禁忌。雄激素对于前列腺的发育和维护是必要的。无论如何,流行病学研究并没有一致地发现内源性血清雄激素浓度与前列腺疾病风险之间存在正相关。虽然最新研究显示5α还原酶抑制剂降低了患低级别前列腺癌的风险,说明抑制雄激素代谢有利于前列腺健康,但是对于高级别前列腺癌并没有类似作用,因此对这些药物化学预防的真正临床效益提出了质疑。鉴于缺乏大样本随机试验,很难了解如何最好地研究雄激素和前列腺疾病发展之间的关系。越来越多研究质疑雄激素在血清中的变化与其在前列腺激素环境中的变化有类似效应或者改变腺体内雄激素的调节过程。需要长期的干预性研究来真正证实雄激素对前列腺组织和疾病风险的操控。然而,现有数据认为恢复血清雄激素至生理水平并不会触发前列腺疾病。     

Influence of age and photoperiod on steroidogenic function of the testis in the golden hamster

The golden (Syrian) hamster is a seasonal breeder, and exposure of adult animals to short days results in severe gonadal regression with morphological features that resemble the immature testis. The purpose of this study was to investigate testicular steroidogenic capacity in the golden hamster and to analyse the influence of age and photoperiod on this process. Hamsters aged 36 days were maintained on a long photoperiod (14L:10D), and adult animals were then exposed to a long or a short photoperiod (6L:18D) for 14 weeks (the period of time required to achieve maximal gonadal regression), to assess circulating levels and in vitro production of testosterone, dihydrotestosterone and androstane-3 alpha, 17 beta-diol. In peripubertal hamsters, androstane-3 alpha, 17 beta-diol was the main circulating androgen detected, whereas in active adult animals, testosterone showed the highest serum levels. In hamsters exposed to a short photoperiod, blood testosterone levels were significantly lower than levels in adult hamsters exposed to a long photoperiod. Exposure of adult hamsters to a short photoperiod produced a marked reduction in serum concentrations of dihydrotestosterone and androstane-3 alpha, 17 beta-diol, which was not accompanied by a decrease in testicular 5 alpha-reductase activity. In the in vitro experiments, active adult testes were less sensitive than inactive adult testes to stimulation of androgen production with hCG, but showed similar sensitivity to the gonads from hamsters aged 36 days. In accordance with circulating androgen concentrations, the principal androgens produced in the in vitro assays from peripubertal and normal adult testes were androstane-3 alpha, 17 beta-diol and testosterone, respectively. Unexpectedly, the main androgen produced from regressed testes under in vitro conditions was androstane-3 alpha, 17 beta-diol. Inactive gonads released more androstane-3 alpha, 17 beta-diol than did normal adult testes and total in vitro androgen production (testosterone + dihydrotestosterone + androstane-3 alpha, 17 beta-diol) from adult testes was not diminished by exposure to a short photoperiod. However, in spite of the significant increase detected in production of androstane-3 alpha, 17 beta-diol in vitro from regressed testes, inactive gonads produced less androstane-3 alpha, 17 beta-diol than did peripubertal testes. In summary, our studies suggest that testicular androgen biosynthetic capacity in adult hamsters exposed to short photoperiod is not reduced and these regressed testes represent an intermediate physiological state between peripubertal and active adult testes. The significant decrease detected in serum androgen concentrations during the involution phase could result from the absence of stimulating pituitary factors, together with a negative regulation of steroidogenesis by different non-steroidal signals originating within and/or outside of the testis.     

Androgens and prostate cancer risk: a prospective study

BACKGROUND: Androgens have been implicated in prostate tumorigenesis, but prospective studies have overall reported no association between circulating levels of androgens and risk of prostate cancer. However, some recent studies have shown that a high level of testosterone increase the risk of non-aggressive tumors but is associated with a decreased risk of aggressive tumors. METHODS: We prospectively measured plasma levels of total testosterone, androstanediol glucuronide (A-diol-g) and sex hormone binding globuline (SHBG) and calculated estimated levels of free testosterone, in a nested case-control study of 392 cases and 392 matched controls. RESULTS: None of the studied hormones were significantly associated with prostate cancer risk in the full study group or in subgroups according to tumor aggressiveness. Odds ratios in the full study group, for top versus bottom quartile, was for total testosterone 1.25 (95% CI = 0.79-2.00; P(trend) = 0.51); free testosterone, 1.31 (95% CI = 0.82-2.07; P(trend) = 0.35); A-diol-g, 0.88 (95% CI = 0.59-1.33; P(trend) = 0.77); and for SHBG, 1.01 (95% CI = 0.64-1.58; P(trend) = 0.94). CONCLUSIONS: We found no significant associations between androgen levels and risk of prostate cancer in this population-based, non-screened cohort.     

One and the same androgen for all? Towards designer androgens

The introduction of designer oestrogens as a treatment modality in hormone replacement in women has invited to consider the concept of compounds with selective androgenic effects for male hormone replacement therapy. The full spectrum of the actions of testosterone may not be necessary of even undesired for certain indications for testosterone treatment. To define for what indications certain androgenic properties are desired and undesired more insight in basic androgen (patho)physiology is required. There is convincing evidence that aromatization of androgenic compounds to oestrogens might be an advantage for maintenance of bone mass and it might also mitigate negative effects of androgens on biochemical parameters of cardiovascular risks; the potentially negative effects of oestrogens on prostate pathology in ageing men needs further elucidation. While the role of dihydro-testosterone (DHT) for the male sexual differentiation and for pubertal sexual maturation is evident, its role in mature and ageing males seems less significant or may even be harmful. It is, however, of note that a negative effect of DHT on prostate pathophysiology is certainly not proven. For male contraception a progestational agent with strong androgenic properties might be an asset. For most of the androgenic actions the critical levels of androgens are not well established. The latter is relevant since the large amount of androgen molecules required for its biological actions (as compared to oestrogens) is an impediment in androgen replacement modalities. There may be room for more biopotent androgens since delivery of large amounts of androgen molecules to the circulation poses problems for treatment modalities.     

Importance of the intracrine metabolism of adrenal androgens in androgen-dependent prostate cancer

The metabolic pathways of androgens and processes by which androgens induce re-growth after androgen deprivation therapy in prostate cancer have not been fully elucidated. In this study, finasteride decreased PSA secretion in medium containing testosterone, androstenedione, androstenediol and dehydroepiandrosterone, whereas dihydrotestosterone (DHT)- and hydroxy-flutamide-induced PSA production was not inhibited by finasteride in LNCaP-FGC cells. The present data show that adrenal androgen precursors do not directly interact with androgen receptors (ARs) but are converted to DHT via the intraprostatic metabolic pathways, resulting in the induction of LNCaP activity. This is the first report confirming this mechanism experimentally and also suggest the use of combined therapies that target ARs and prevent the formation of DHT within prostate cancer cells to achieve optimal therapeutic efficacy.     

Free testosterone is an independent predictor of BMD and prevalent fractures in elderly men: MrOS Sweden.

The role of androgens for bone health in elderly men is unclear. We show that free testosterone within the normal range is a predictor of BMD at predominantly cortical bone sites and of previous osteoporosis-related fractures in elderly Swedish men. INTRODUCTION: Osteoporosis-related fractures constitute a major health concern not only in women but also in men. Previous studies have clearly shown that serum levels of estradiol are associated with BMD, whereas more conflicting data have been presented regarding the predictive value of testosterone (T) for bone health in elderly men. The aim of this study was to investigate if serum levels of T are associated with BMD and/or prevalent fractures in a large cohort of elderly men. MATERIALS AND METHODS: In the Swedish part of the MrOS study (n = 2908; average age, 75.4 years), bone parameters were measured using DXA, and prevalent fractures were recorded using standardized questionnaires and by vertebral X-ray analyses. Serum levels of total T, total estradiol (E2), and sex hormone-binding globulin (SHBG) were measured by radioimmunoassay, and free T (FT) and free E2 (FE2) were derived from the mass action equations. Height, weight, age, physical activity, smoking habits, and calcium intake were included together with FT and FE2 in regression models for BMD. RESULTS: FT was an independent positive predictor of BMD in total body, total hip, femur trochanter, and arm but not in the lumbar spine. The highest independent predictive value of FT was found in the arm and the hip (with a relatively high content of cortical bone). FE2 was an independent predictor of BMD at all bone sites studied, and the highest predictive value was seen for lumbar spine (with relatively high content of trabecular bone) BMD. FT but not FE2 was a positive predictor of total body bone area and BMC. FT levels below the median were independent predictors of prevalent osteoporosis-related fractures (OR, 1.56; 95% CI, 1.14-2.14; p < 0.01) and X-ray-verified vertebral fractures (OR, 2.00; 95% CI, 1.34-2.86; p < 0.001). The predictive value of FT for prevalent fractures was not affected by adjustment for BMD. CONCLUSIONS: These findings show that variation of FT within the normal range is an independent but modest predictor of BMD at predominantly cortical bone sites and of previous osteoporosis-related fractures in elderly men. Our data indicate that not only estrogens but also androgens are of importance for bone health in elderly men. Longitudinal studies investigating the predictive value of T for fracture risk in elderly men are required.