Different conversion metabolic rates of testosterone are associated to hormone-sensitive status and -response of human prostate cancer cells

Characterization of Precursor-Dependent Steroidogenesis in Human Prostate Cancer Models

Castration-resistant prostate tumors acquire the independent capacity to generate androgens by upregulating steroidogenic enzymes or using steroid precursors produced by the adrenal glands for continued growth and sustainability. The formation of steroids was measured by liquid chromatography-mass spectrometry in LNCaP and 22Rv1 prostate cancer cells, and in human prostate tissues, following incubation with steroid precursors (22-OH-cholesterol, pregnenolone, 17-OH-pregnenolone, progesterone, 17-OH-progesterone). Pregnenolone, progesterone, 17-OH-pregnenolone, and 17-OH-progesterone increased C21 steroid (5-pregnan-3,20-dione, 5-pregnan-3,17-diol-20-one, 5-pregnan-3-ol-20-one) formation in the backdoor pathway, and demonstrated a trend of stimulating dihydroepiandrosterone or its precursors in the backdoor pathway in LNCaP and 22Rv1 cells. The precursors differentially affected steroidogenic enzyme messenger RNA (mRNA) expressions in the cell lines. The steroidogenesis following incubation of human prostate tissue with 17-OH-pregnenolone and progesterone produced trends similar to those observed in cell lines. Interestingly, the formation of C21 steroids from classical pathway was not stimulated but backdoor pathway steroids (e.g., 5-pregnan-3,20-dione, 5-pregnan-3-ol-20-one) were elevated following incubations with prostate tissues. Overall, C21 steroids were predominantly formed in the classical as well as backdoor pathways, and steroid precursors induced a diversion of steroidogenesis to the backdoor pathway in both cell lines and human prostate tissue, and influenced adaptive steroidogenesis to form C21 steroids.

Influence of sensitization and allergen provocation procedures on the development of allergen-induced bronchial hyperreactivity in conscious, unrestrained guinea-pigs

The effects of different sensitization and allergen provocation regimens on the development of allergen-induced bronchial hyperreactivity (BHR) to histamine were investigated in conscious, unrestrained guinea-pigs. Similar early and late phase asthmatic reactions, BHR for inhaled histamine after the early (6 h) as well as after the late reaction (24 h), and airway inflammation were observed after a single allergen provocation in animals sensitized to produce mainly IgG or IgE antibodies, respectively. Repeating the allergen provocation in the IgE-sensitized animals after 7 days, using identical provocation conditions, resulted in a similar development of BHR to histamine inhalation. Repetition of the allergen provocation during 4 subsequent days resulted in a decreased development of BHR after each provocation, despite a significant increase in the allergen provocation dose necessary to obtain similar airway obstruction. The number of inflammatory cells in the bronchoalveolar lavage was not significantly changed after repeated provocation, when compared with a single allergen provocation. Finally, we investigated allergen-induced bronchial hyperreactivity by repetition of the sensitization procedure at day 7 and 14 (booster), followed by repeated allergen provocation twice a week for 5 weeks. Surprisingly, no BHR to histamine could be observed after either provocation, while the number of inflammatory cells in the bronchoalveolar lavage fluid after 5 weeks was enhanced compared with controls. These data indicate that both IgE and IgG sensitized guinea-pigs may develop bronchial hyperreactivity after a single allergen provocation. Repeated allergen exposure of IgE sensitized animals causes a gradual fading of the induced hyperreactivity despite the on-going presence of inflammatory cells in the airways, indicating a mechanism of reduced cellular activation.

Androgen metabolism and inhibition of interleukin-1 synthesis in primary cultured human synovial macrophages

The presence of androgen receptors on synovial macrophages in human normal and rheumatoid synovial tissues has been described previously. It is now reported that primary cultured human macrophages obtained from normal and rheumatoid synovia express functional androgen receptors. We have investigated the capacity of cultured macrophages to metabolize androgens and have found that these cells were capable of metabolizing testosterone to the bioactive metabolite dihydrotestosterone. Therefore, macrophages contain the key enzymes of steroidogenesis, in particular the 5α-treductase. Furthermore, interleukin-1β production by primary cultured rheumatoid macrophages was analysed, following exposure to physiological concentrations of testosterone (10⁻⁸ M). A significant decrease of IL-1β levels in conditioned media after 24 h (p < 0.05) was observed. It is concluded that androgens may act directly on human macrophages and may interfere with some of their functions via receptor-dependent mechanisms.

Estrogen signalling through amphiregulin may be implicated in human hepatocellular carcinoma

BACKGROUND

We investigated aromatase (Aro)-driven estrogen formation in non-tumoral and malignant liver tissues and cells, also in relation to expression of the estrogen receptors α and β (ERα and ERβ) and amphiregulin (AREG), aiming to gain insights into the potential role of estrogens in human hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Chromatographic and reverse transcriptase polymerase chain reaction (RT-PCR) analyses were used to assess activity and expression of the Aro enzyme and AREG as well as the expression of wild-type and variant ERs, both in vivo and in vitro.

RESULTS

Following 24 h and 72 h incubation of liver tissues or cells with testosterone, human HCC tissues and HepG2 hepatoma cells showed elevated Aro activity (estrogen formation, respectively, of 20% and 52%-99%). By contrast, no Aro activity could be detected in non-tumoral tissues and HA22T liver cancer cells. Cirrhotic samples and Huh7 cells exhibited intermediate enzyme activity, with estrogen formation of 4% and 34%, respectively. Markedly lower or undetectable Aro mRNA levels were observed in HA22T cells and non-tumoral liver tissues compared with HepG2 cells and HCC samples. Cirrhotic specimens displayed variable transcript levels. Interestingly, no or low expression of wild-type ERα and ERβ could be observed in liver cancer cells and malignant tissues. However, ubiquitous expression of the hERα46 variant and occasional expression of the hERβ2/Cx variant were observed in cancer tissues and cells.

CONCLUSIONS

It is noteworthy that the pattern of wild-type ERα was inversely related to Aro, whilst AREG expression was consistently associated with that of Aro. This combined evidence suggests that locally elevated Aro activity may increase malignant cell proliferation also through AREG signalling.

The mechanism of action of estrogen in castration-resistant prostate cancer: clues from hormone levels

BACKGROUND

Estrogen therapy plays a role in the management of castration-resistant prostate cancer (CRPC), although the mechanism of action is not fully known. This current analysis reports the relationship of change in adrenal androgen levels and prostate-specific antigen (PSA) response in patients with CRPC treated with estrogen therapy.

PATIENTS AND METHODS

Hormone levels were measured for patients with CRPC treated in a multicenter phase II trial of 2 estrogen-containing compounds, the herbal supplement PC-SPES and diethylstilbestrol (DES), with known efficacy in CRPC. Patients with castrate levels of testosterone were randomized to initially receive either PC-SPES 960 mg t.i.d. or DES 3 mg/day. Levels of testosterone, dihydrotestosterone (DHT), estradiol, estrone, sex hormone-binding globulin (SHBG), dehydroepiandrosterone (DHEA), DHEA-sulfate (DHEA-S), and androstenedione were obtained at baseline and at 12-week intervals until disease progression. Hormone levels were obtained for 38 patients, 20 treated with PC-SPES and 18 treated with DES.

RESULTS

Significant declines between baseline and 12 weeks of treatment were observed in levels of serum testosterone (P < .001), estrone (P = .02), and DHEA (P < .001). The percent changes at 12 weeks in these hormone levels were inversely proportional to baseline values as measured by Spearman's rank correlation (testosterone: -0.41, P = .01; estrone: -0.64, P = .0001; DHEA: -0.39, P = .02). Levels of SHBG increased in almost all of the patients (97%), with a median percent increase of > 5-fold (P < .0001). Of the 38 evaluable patients, 15 (39% [95% CI, 24%-57%]) experienced a > 50% decline in PSA level. There was no significant difference between treatment groups or between responders and nonresponders in baseline distributions for any of the hormones. At follow-up, 73% of the responders had a decline in the level of DHEA-S compared with 41% of the nonresponders, resulting in a difference in the distribution of the percent change between the subsets (Mann-Whitney test: P = .03). Conversely, 64% of the responders compared with 30% of the nonresponders experienced an increase in DHT, with differing distributions of percent change (P = .02).

CONCLUSION

Androgens decline in response to estrogen therapy. A decline in DHEA-S and a rise in DHT are both associated with a decline in PSA while patients receive estrogen therapy.

Androgen metabolism and biotransformation in nontumoral and malignant human liver tissues and cells

There is indirect multiple evidence that hints at a potential role of sex steroids in development and progression of human hepatocellular carcinoma (HCC). In the present study, we have investigated androgen metabolism in a panel of human liver cancer cell lines (HA22T, Huh7, HepG2) and in normal, cirrhotic and malignant human liver tissues aiming to dissect the potential impact of individual enzyme activities and their products in normal and diseased human liver, both in vivo and in vitro. Using our intact cell analysis we were able to assess rates and pathways of androgen metabolism in living conditions. Overall, incubation of cultured cells or tissue minces with either testosterone (T) or androstenedione (Ad) used as precursor resulted in a large extent of 17betaoxidation of T to Ad (cells: 28-77%; tissues: 35-50%). In malignant liver cell lines, both HA22T and Huh7 cells showed consistent amounts of the 5alpha-reductase enzyme products (18% and 15%, respectively), while 5beta-reductase activity was more pronounced in Huh7 cells (18%) than in HA22T cells (1.8%). Interestingly, a significant extent of estrogen formation could be observed in Huh7 cells (5.4-11.5%), while no aromatase activity could be detected in HA22T cells. In HepG2 cells, along with a relatively high proportion of Ad, estrogens represented the most prominent (50-55%) end product of androgen metabolism, regardless of the precursor used. In liver tissues, equivalent results could be obtained, with a consistent proportion of 17betaoxidation of T to Ad (35-50%) being observed in the majority of samples. However, while normal liver tissue samples exhibited a minor proportion of bioactive androgens (3.4%) with no aromatase products, HCC tissues showed a significant extent of aromatase activity (nearly 20%) with estrogen representing the most prominent metabolic product after 24h incubation with either T or Ad. HCV and alcoholic cirrhotic tissues displayed different patterns of androgen metabolism. The former produced limited amounts of bioactive androgens (5.3%) and considerable levels of the intermediate aromatase product 19OH-Ad (up to 28%), the latter exhibited a prevalence of androgen degradation through the 5beta-reductase pathway (9.8%) and a significant extent of aromatase activity (16% as a whole). In conclusion, three major metabolic states could be depicted, depending on prevalent pathways of androgen metabolism and steroid receptor status: estrogenic, androgenic, and mixed. This model supports the idea that local estrogen biosynthesis may be implicated in human HCC and provides a basis for the exploitation of aromatase inhibitors and/or ER antagonists or selective estrogen receptor modulators (SERMs) as a new therapeutic strategy in HCC patients.

Electron emission from photo-excited testosterone in water-ethanol solution

Testosterone (TES; 4-androstene-17beta-ol-3-on) is found for the first time to eject electrons from its singlet excited state in water-ethanol solvent mixture. This ability was very recently also observed for 17beta-estradiol (17betaE2) and progesterone (PRG)/1/. With increasing TES-concentration, the yield of solvated electrons (e(s)(-)) is decreasing, because of "associate" formation. At higher absorbed UV-doses (lambda=254 nm) the e(s)(-) yield is passing a sharp maximum by formation of TES-ethanol adducts, which are able likewise to emit electrons when excited. At prolonged irradiation the resulting photolytic products of TES-ethanol adducts are also able to emit electrons. The capability of the hormones: 17betaE2, PRG and TES to eject electrons and the resulting metabolites, some of which can induce cancer, is discussed.

Estrogen and prostate cancer: an eclipsed truth in an androgen-dominated scenario

Prostate cancer is the commonest non-skin cancer in men. Incidence and mortality rates of this tumor vary strikingly throughout the world. Although several factors have been implicated to explain this remarkable variation, lifestyle and dietary factors may play a dominant role, with sex hormones behaving as intermediaries between exogenous factors and molecular targets in development and progression of prostate cancer. Human prostate cancer is generally considered a paradigm of androgen-dependent tumor; however, estrogen role in both normal and malignant prostate appears to be equally important. The association between plasma androgens and prostate cancer remains contradictory and mostly not compatible with the androgen hypothesis. Similar evidence apply to estrogens, although the ratio of androgen to estrogen in plasma declines with age. Apart from methodological problems, a major issue is to what extent circulating hormones can be considered representative of their intraprostatic levels. Both nontumoral and malignant human prostate tissues and cells are endowed with key enzymes of steroid metabolism, including 17betahydroxysteroid dehydrogenase (17betaHSD), 5beta-reductase, 3alpha/3betaHSD, and aromatase. A divergent expression and/or activity of these enzymes may eventually lead to a differential prostate accumulation of steroid derivatives having distinct biological activities, as it occurs for hydroxylated estrogens in the human breast. Locally produced or metabolically transformed estrogens may differently affect proliferative activity of prostate cancer cells. Aberrant aromatase expression and activity has been reported in prostate tumor tissues and cells, implying that androgen aromatization to estrogens may play a role in prostate carcinogenesis or tumor progression. Interestingly, many genes encoding for steroid enzymes are polymorphic, although only a few studies have supported their relation with risk of prostate cancer. In animal model systems estrogens, combined with androgens, appear to be required for the malignant transformation of prostate epithelial cells. Although the mechanisms underlying the hormonal induction of prostate cancer in experimental animals remain uncertain, there is however evidence to support the assumption that long term administration of androgens and estrogens results in an estrogenic milieu in rat prostates and in the ensuing development of dysplasia and cancer. Both androgen and estrogen have been reported to stimulate proliferation of cultured prostate cancer cells, primarily through receptor-mediated effects. As for estrogens, the two major receptor types, ERalpha and ERbeta, are expressed in both normal and diseased human prostate, though with a different cellular localization. Since these two receptors are different in terms of ligand binding, heterodimerization, transactivation, and estrogen response element activity, it is likely that an imbalance of their expression may be critical to determine the ultimate estrogen effects on prostate cancer cells. In prostate cancer, ERbeta activation appears to limit cell proliferation directly or through ERalpha inhibition, and loss of ERbeta has been consistently associated with tumor progression. Several splicing variants of both ERalpha and ERbeta exist. Little is known about their expression and function in the human prostate, although reciprocal regulation and interaction with gene promoter both warrant further investigation. In summary, although multiple consistent evidence suggests that estrogens are critical players in human prostate cancer, their role has been only recently reconsidered, being eclipsed for years by an androgen-dominated interest.

Estrogens and mechanisms of prostate cancer progression

Prostate cancer is a major health issue in westernized countries, being considered a prototypical age-related, androgen-dependent tumor. However, data on the association between circulating androgens and prostate cancer have been inconsistent and mostly not compatible with the androgen hypothesis. In addition, plasma androgen-to-estrogen ratio appears to decrease with age, suggesting that estrogens may also have a role. Results from our own and others' studies suggest that circulating steroids cannot be considered representative of their actual intraprostatic levels. This is a consequence of the expression and/or activity of steroid enzymes, including 17beta-hydroxysteroid dehydrogenase (17beta-HSD), 5alpha-reductase, 3alpha/3beta-HSD, and aromatase, which may eventually lead to a differential tissue accumulation of steroid derivatives having distinct biological activities. Interestingly, many of the genes encoding for steroid enzymes are highly polymorphic in nature, although only a few studies have investigated their relation with prostate cancer and the data presently available are inconclusive. Locally produced or metabolically transformed estrogens may differently affect proliferative activity of prostate cancer cells. In our studies, estrogen may either stimulate or decrease prostate cancer cell growth, also depending on the receptor status. In particular, an imbalance of ERalpha and ERbeta expression may be critical to determine the ultimate estrogen effects on prostate cancer cell growth. Furthermore, evidence is accumulating that estrogens regulate gene transcription through an array of estrogen-response elements (EREs) and non-EREs, either ligand-dependent or -independent. This is further complicated by the presence of receptor isoforms, distinct cofactor interaction, and potential heterodimerization. Based on this combined evidence, a hypothetical model of prostate cancer progression is presented.

Sex steroid hormone metabolism and prostate cancer

The growth and function of the prostate is dependent on androgens. The two predominant androgens are testosterone, which is formed in the testis from androstenedione and 5alpha-dihydrotestosterone, which is formed from testosterone by 5alpha-reductases and is the most active androgen in the prostate. Prostate cancer is one of the most common cancers among men and androgens are involved in controlling the growth of androgen-sensitive malignant prostatic cells. The endocrine therapy used to treat prostate cancer aims to eliminate androgenic activity from the prostatic tissue. Most prostate cancers are initially responsive to androgen withdrawal but become later refractory to the therapy and begin to grow androgen-independently. Using LNCaP prostate cancer cell line we have developed a cell model to study the progression of prostate cancer. In the model androgen-sensitive LNCaP cells are transformed in culture conditions into more aggressive, androgen-independent cells. The model was used to study androgen and estrogen metabolism during the transformation process. Our results indicate that substantial changes in androgen and estrogen metabolism occur in the cells during the process. A remarkable decrease in the oxidative 17beta-hydroxysteroid dehydrogenase activity was seen whereas the reductive activity seemed to increase. The changes suggest that during transformation estrogen influence is increasing in the cells. This is supported by the cDNA microarray screening results which showed over-expression of several genes up-regulated by estrogens in the LNCaP cells line representing progressive prostate cancer. Since local steroid metabolism controls the bioavailability of active steroid hormones in the prostate, the variations in steroid-metabolizing enzymes during cancer progression may be crucial in the regulation of the growth and function of the organ.

Interlaboratory comparison of four in vitro assays for assessing androgenic and antiandrogenic activity of environmental chemicals

We evaluated and compared four in vitro assays to detect androgen agonists and antagonists in an international interlaboratory study. Laboratory 1 used a cell proliferation assay (assay 1) with human mammary carcinoma cells stably transfected with human androgen receptor. The other laboratories used reporter gene assays, two based on stably transfected human prostate carcinoma cells (assay 2) or human mammary carcinoma cells (assay 4), and the third based on transient transfection of Chinese hamster ovary cells (assay 3). Four laboratories received four coded compounds and two controls: two steroidal androgens, two antiandrogens, an androgenic control, 5alpha-dihydrotestosterone (DHT), and an antiandrogenic control, bicalutamide (ICI 176,334). All laboratories correctly detected the androgenic activity of 4-androsten-3,17-dione and 17alpha-methyltestosterone. For both compounds, the calculated androgenic potencies relative to the positive control (RAPs) remained within one order of magnitude. However, laboratory 3 calculated a 50-fold higher RAP for 4-androsten-3,17-dione. All assays detected and quantified the antiandrogenic effect of vinclozolin [median inhibitory concentration (IC50) values ranging from 1.1 times symbol 10(-7) M to 4.7 times symbol 10(-7) M]. In assays 2 and 3, vinclozolin showed partial androgenic activity at the highest concentrations tested. For vinclozolin, calculated antiandrogenic potencies relative to bicalutamide (RAAPs) differed no more than a factor of 10, and IC50 values matched those of bicalutamide. Similarly, we found antiandrogenic activity for tris-(4-chlorophenyl)methanol. RAAP values were between 0.086 and 0.37. Three assays showed cytotoxicity for this compound at or above 1 times symbol 10(-5) M. In summary, all assays proved sensitive screening tools to detect and quantify androgen receptor-mediated androgenic and antiandrogenic effects of these chemicals accurately, with coefficients of variation between 8 and 90%.

Association Study of Polymorphisms in the Human Estrogen Receptor Alpha Gene and Prostate Cancer Risk

OBJECTIVES

Prostate cancer is a very common hormone-related malignancy in Western countries. It is initially dependent on androgen stimulation but in vitro growth of prostate cancer cells are also dependent on estrogen. Our goal was to elucidate if some polymorphisms of estrogen receptor alpha gene might be associated with the risk of prostate cancer.

METHODS

Using DHPLC techniques, each coding exon of the estrogen receptor alpha gene was screened for new polymorphisms in germline DNA from 96 healthy controls and 96 sporadic prostate cancer cases. Identified polymorphisms were then genotyped and their distribution compared between the two populations.

RESULTS

Thirteen polymorphisms were identified. A difference was found in the distribution of one newly identified polymorphism, namely a GGGA repeat located in the first intron of the gene. The common wild type genotype consisted of two alleles with five GGGA repetitions (5/5 genotype). Indeed this 5/5 genotype was found in 294/296 controls (99.3%) and 285/294 patients (96.9%; OR, 4.6; 95% CI, 0.99-21.67). Among the nine patients with a different genotype, one was 4/5, seven were 5/6 and one was 6/6.

CONCLUSION

These results suggest that variants of the GGGA polymorphism from the estrogen receptor alpha gene may be associated with an increased risk of developing prostate cancer.

Altered androgen metabolism eventually leads hepatocellular carcinoma to an impaired hormone responsiveness

Sex steroid hormones are thought, among several other risk factors, to play a role in liver malignancies. For example, from epidemiological studies in hepatocellular carcinoma (HCC), a clear disadvantage for male sex is evident. In addition, elevated levels of serum testosterone (T) and increased T to Estradiol (E(2)) ratio have been reported to predict an increased risk of HCC for male cirrhotic patients. On the other hand, palliative treatment of liver cancer patients with anti-hormones has been widely used in the past. However, the molecular mechanism(s) underlying sex steroid action on either normal or transformed liver cells, have not yet been fully clarified, nor endocrine discriminants have been satisfactorily assessed for an adequate characterization of liver cancer tissues. In this paper, we report studies on hormonal status of human liver tissues and cells, especially focusing on androgens, to better define endocrine end-points of interest for HCC. A consistent evidence from ex vivo or in vitro systems strongly suggests that high affinity binding sites of androgens are expressed at sufficient concentrations to induce a biological response in either normal or phenotipically transformed hepatocytes; in the latter, however, high heterogeneity and/or more scattering concentrations were encountered. Further, experimental data seem to suggest that lack of response to androgens may be due to a rapid metabolic conversion of steroids by neoplastic tissues and cells. Cancer hepatocytes privilege in fact 5beta more than 5alpha metabolic pathway of androgens. This may eventually lead biologically active androgens to be transformed into less active derivatives, as it occurs for T which is massively converted (>90% at 6 h) thus hindering the whole mechanism of action of androgens.

Adrenal steroids in human prostatic cancer cell lines

Adrenal androgens function as an androgen source within prostate and androgen target tissue. This study compares the ability of three human prostatic cancer cell lines to metabolize the adrenal androgens, dehydroepiandrosterone (DHEA), and androstenedione under living culture conditions. Androgen-independent cell lines PC-3 and DU145 and androgen-dependent cell line LNCaP were investigated. The effect of glucuronide and sulfate conjugates was also investigated. There was a strong tendency in PC-3 or DU145 to convert androstenedione to DHEA or DHEA-S reservoir. On the other hand, LNCaP was capable of converting DHEA into androstenedione and subsequently into dihydrotestosterone (DHT). Moreover, androgens were converted into a glucuronide conjugate in LNCaP, but not in PC-3 or DU145. As a result, the metabolism of the adrenal precursor shifted to androgen formation in LNCaP. This could be confirmed by means of reverse transcription-PCR of uridine diphosphoglucuronosyl-transferase (UGT) 2B15. Kinetic properties of UGT activity in LNCaP revealed DHT to be a better substrate than testosterone. In conclusion, the findings show that the adrenal precursor pool has the potential to contribute to the regulation of prostatic cells. Moreover, the presence of UGT activities in LNCaP may have a regulatory effect on the active androgen level in the intracellular environment.

Double involvement of extramammary Paget's disease in the genitalia and axilla

We here reported a case of an 82-year-old man with double involvement of extramammary Paget's disease in the genitalia and axilla. Physical examination revealed erythema and reddish tumors on the pubic area and scrotum and irregular-shaped erythema on the left axilla. The skin biopsy sample from the genital area showed Paget's cells in the epidermis and upper dermis. The specimen from the left axilla showed Paget's cells scattered in the epidermis but not in the dermis.

A stable prostatic bioluminescent cell line to investigate androgen and antiandrogen effects

We developed a new stable prostatic cell line expressing the human androgen receptor (AR) and the AR-responsive reporter gene to generate a powerful tool for investigating androgen action and for rapid screening of agonists and antagonists. The AR-deficient PC-3 cells were stably transfected with pSG(5)-puro-hAR and pMMTV-neo-Luc. After selection with puromycin and neomycin, one highly inducible clone was isolated and named PALM, for PC-3-Androgen receptor-Luciferase-MMTV. The expression of hAR was confirmed by western blot and steroid-binding assays on the whole cells. The transcriptional activity of the clone was measured after incubation of cells with increasing concentrations of synthetic R1881 or natural androgens (DHT and testosterone). The three agonists had the same maximal activity at 0.1 microM and the fold induction was equal to 20. The agonist and antagonist activities of the steroidal antiandrogens (cyproterone acetate and RU2956) and the non-steroidal antiandrogens (nilutamide, bicalutamide, inocoterone and hydroxyflutamide) measured with the PALM cells were in good correlation with the results obtained with transiently transfected cells. The selectivity in steroid transactivation was demonstrated with estradiol, progesterone, cortisol, dexamethasone and aldosterone. Spironolactone and RU486 showed partial agonist and antagonist activities, whereas R5020 presented only a partial antagonist activity. We here demonstrate that this stable transfectant provides an accurate tool for studying wild-type human AR activation and its regulation by androgens and antiandrogens in a human prostatic epithelial cell, which is routinely available and remains androgen-responsive in vitro.

5alpha-reductase isozymes and aromatase are differentially expressed and active in the androgen-independent human prostate cancer cell lines DU145 and PC3

BACKGROUND

The presence and possible role of androgen-metabolizing enzymes in androgen-independent prostate carcinoma (CaP) are still unclear. The aim of the present study was: 1) to evaluate the pattern of androgen metabolism (relative production of 5alpha-reduced vs. 17-keto androgens); and 2) to analyze whether one or both the two known 5alpha-reductase isoforms (5alpha-R1 and 5alpha-R2) and the aromatase (Aro) are expressed and active in this pathology.

METHODS

Two different cell lines (DU145 and PC3) were used as a model of androgen-independent human CaP. In these cells, the expression of the two 5alpha-Rs and of Aro were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot, using specific sets of oligoprimers and of [(32)P]-labeled oligoprobes; the enzymatic activities of 5alpha-R and of Aro were evaluated by radioenzymatic methods. The pH optimum for the activity of the two 5alpha-Rs was assessed in cell homogenates at different pH (from 3.5-8), using substrate concentrations similar either to 5alpha-R1 or to 5alpha-R2 Kms.

RESULTS

The two CaP cell lines DU145 and PC3, although unresponsive to androgens, possess the enzymatic machinery involved in the metabolism of this class of hormonal steroids: 5alpha-Rs, which allow their transformation into 5alpha-reduced steroids (5alpha-dihydrotestosterone, DHT, and 5alpha-androstandione, 5alpha-A), and 17beta-hydroxysteroid-oxidoreductase (17beta-HSD), which interconverts testosterone (T) and androstenedione (ADIONE); however, the two cell lines show differences in the rate of formation of these metabolites. Furthermore, two cell lines expressed the type 1 isoform of 5alpha-R, but only DU145 cells also possess 5alpha-R2. Aro is expressed and active in DU145 as well as in PC3 cells.

CONCLUSIONS

The present findings suggest that T might still be indirectly active in androgen-unresponsive CaP through its local conversion into estrogens by the action of Aro; the biological role played by the two 5alpha-Rs in androgen-independent CaP deserves further investigation.

Endocrine end-points in rheumatoid arthritis

Our previous studies are reviewed and at the same time preliminary experimental observation to the topic of endocrine end-points in autoimmune disease is introduced. To this end, we have used rheumatoid arthritis (RA), including synovial fluids and primary cultures of synovial macrophages, as a model system in order to investigate (a) expression and subcellular localization of high-affinity sites of steroid binding in immune effector cells; (b) steroid metabolic profiles in both male and female RA patients, as compared to healthy subjects; and (c) activities of key steroid enzymes that govern intratissue accumulation of sex hormones. In RA tissues and cells, the concurrent evidence for (1) androgen and/or estrogen receptors, (2) high concentrations of biologically active steroids, (3) key enzymes of steroid metabolism, and (4) significant changes of estrogen to androgen ratio, all strongly suggests that individual immune cells, including synovial macrophages, may behave as steroid-sensitive cells, namely, they may represent a target for sex steroids, supporting the hypothesis of a potential endocrine regulation of the immune response also in RA disease. In this respect, definition of several endocrine end-points may have important implications for the treatment of rheumatic disease and other immunological disorders.

Isolation and androgen regulation of the human homeobox cDNA, NKX3.1

BACKGROUND

The prostate is dependent on androgens for development and maintenance of its differentiated phenotype. We have applied the technique of differential display PCR to the androgen-sensitive prostate cancer cell line LNCaP to isolate androgen-responsive genes.

METHODS

The technique of DD-PCR was applied to androgen-stimulated LNCaP cell RNA to detect and isolate androgen-responsive genes.

RESULTS

The human homeobox gene NKX3.1, the homologue to mouse Nkx3.1, recently isolated by Beiberich et al. [J Biol Chem 1996;271:31779-31782], was detected and cloned. NKX3.1 is induced by androgens in a time- and concentration-dependent manner. NKX3.1 is induced 6- to 7-fold in 12 hr, with a significant induction seen in 2 hr. This regulation is at the level of transcription, as androgens increase the number of new NKX3.1 transcripts, and de novo protein synthesis is not required. In humans, NKX3.1 is expressed most highly in the prostate, with a much lower level of expression seen in the testis. No other tissue examined showed detectable levels of NKX3.1 expression.

CONCLUSIONS

NKX3.1 is an androgen-regulated, prostate-specific homeobox gene. We hypothesize that it may play a role in the development and differentiation of the prostate.

5alpha-reductase and 17beta-hydroxysteroid dehydrogenase expression in epithelial cells from hyperplastic and malignant human prostate

The aim of this study on testosterone (T) metabolism in benign prostatic hyperplasia (BPH) and prostatic cancer was to compare the formation of metabolites in freshly isolated epithelial cells and in cells of long-term cultures (2 passages) and to identify the 5alpha-reductase (5alpha-R) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) isoforms responsible for metabolite formation. Androst-4-enedione (A), dihydrotestosterone (DHT) and 5alpha-androstanedione (5alpha-A) formation were measured by high-performance liquid chromatography coupled to a Flo-one HP radioactivity detector. Enzyme isoforms were studied by Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR). T conversion into A by 17beta-HSD, rather than reduction into DHT by 5alpha-R, was by far the predominant activity in cultured epithelial cells. The metabolic profile did not differ substantially between BPH and cancer cells. Long-term cell culture led to an increase in A formation compared with the level recorded in freshly isolated cells, with no significant incidence on the relative DHT level. According to RT-PCR results, both 5alpha-R isoforms (1 and 2) and 2 17beta-HSD isoforms (2 and 3) are present in epithelial cell cultures and in tissues. According to Northern blot analyses, the mRNAs for 5alpha-R2 and 17beta-HSD4 are expressed in tissue and those for 5alpha-R1 and types 2 and 4 17beta-HSD in isolated cell cultures. Moreover, finasteride, a specific 5alpha-R2 inhibitor, inhibits DHT and 5alpha-A formation in long-term cell culture of adenocarcinoma epithelial cells plated on Matrigel, suggesting a 5alpha-R2 expression. Thus, although 5alpha-R2 is present in freshly isolated epithelial cell cultures and in long-term epithelial cells cultured on Matrigel and predominates in prostate tissue, it is the 5alpha-R1 isoform that is preferentially expressed in epithelial cell cultures.

Expression of different 17beta-hydroxysteroid dehydrogenase types and their activities in human prostate cancer cells

The 17beta-hydroxysteroid dehydrogenase (17betaHSD) enzyme system governs important redox reactions at the C17 position of steroid hormones. Different 17betaHSD types (no. 1-4) have been identified to date in peripheral human tissues, such as placenta, testis, and breast. However, there is little information on their expression and activity in either normal or malignant prostate. In the present work, we have inspected pathways of 17beta-oxidation of either androgen or estrogen in human prostate cancer cells (LNCaP, DU145, and PC3) in relation to the expression of messenger RNAs (mRNAs) for 17betaHSD types 1-4. These cell systems feature distinct steroid receptor status and response to hormones. We report here that high expression levels of 17betaHSD4 were consistently observed in all three cell lines, whereas even greater amounts of 17betaHSD2 mRNA were detected solely in PC3 cells. Neither 17betaHSD1 nor 17betaHSD3 mRNAs could be detected in any cell line. From a metabolic standpoint, intact cell analysis showed a much lower extent of 17beta-oxidation of both androgen [testosterone (T)] and estrogen [estradiol (E2)] in LNCaP and DU145 cells compared to PC3 cells, where a greater precursor degradation and higher formation rates of oxidized derivatives (respectively, androstenedione and estrone) were observed. Using subcellular fractionation, we have been able to differentiate among 17betaHSD types 1-4 on the basis of their distinct substrate specificities and subcellular localization. This latter approach gave rise to equivalent results. PC3 cells, in fact, displayed a high level of microsomal activity with a low E2/T activity ratio and approximately equal apparent Km values for E2 and T, suggesting the presence of 17betaHSD2. Dehydrogenase specific activity with both E2 and T was also detected, although at lower levels, in LNCaP and DU145 cells. No evidence for reductase activity could be obtained in either the soluble or microsomal fraction of any cell line. As comparable expression levels of 17betaHSD4 were seen in the three cell lines, 17betaHSD2 is a likely candidate to account for the predominant oxidative activity in PC3 cells, whereas 17betaHSD4 may account for the lower extent of E2 oxidation seen in both LNCaP and DU145 cells. This is the first report on the expression of four different 17betaHSD types in human prostate cancer cells. It ought to be emphasized that for the first time, analysis of different 17betaHSD activities in either intact or fractionated cells harmonizes with the expression of relevant mRNAs species.

Molecular expression of 17 beta hydroxysteroid dehydrogenase types in relation to their activity in intact human prostate cancer cells

In the present study we have inspected estrogen metabolism in cultured human prostate cancer cells (LNCaP, DU145, PC3), in relation to the expression of mRNAs for different 17 beta hydroxysteroid dehydrogenase (17 beta HSD) enzymes (from 1 to 4). Using an intact cell analysis, we have compared precursor degradation and product formation after incubation of cells with physiological amounts of radioactive E2 or estrone (E1) for 24-72 h and subsequent reverse-phase high performance liquid chromatography analysis. The LNCaP and DU145 cells only partly converted E2 to E1 (26 and 13% at 72 h, respectively), giving rise to an appreciable production of E2 from E1 (nearly 20% in all cases). Conversely, PC3 cells revealed a massive E2 oxidation to E1 (up to 90% by 72 h) and a scant formation of E2 (<2%) from E1. In addition, an appreciable formation of 16 alpha OHE1 was seen in either PC3 (11%) or DU145 (5%) cells. respectively using E2 or E1 as precursor. All three cell lines exhibited marked amounts of 17 beta HSD4 mRNA species, whilst even greater amounts of 17 beta HSD2 transcript were found in PC3 cells only. No mRNA for either 17 beta HSD1 or 17 beta HSD3 could be detected in any cell line. The present evidence indicates that pathways of estrogen metabolism are distinctly governed in prostate cancer cells depending on their endocrine status, being associated with a differential expression of mRNA for different 17 beta HSD enzymes.

Characterization of 17beta-hydroxysteroid dehydrogenase isoenzyme expression in benign and malignant human prostate

In the present study, expressions of 17beta-hydroxysteroid dehydrogenase (17HSD) types 1, 2, and 3, 5alpha-reductase type 2 and human androgen receptor mRNAs were determined in 12 benign prostatic hyperplasia and 17 prostatic carcinoma specimens. 17HSD type 2 was found to be the principle isoenzyme expressed in the prostate. Significantly higher expressions of 17HSD type 2 and 5alpha-reductase type 2 were detected in benign prostatic hyperplasia compared with the carcinoma specimens. Expression of the androgen receptor in the 2 groups was not significantly different. 17HSD type 3 mRNA was not detected in any of the specimens investigated. Only low constructive expression of the 2.3 kb mRNA of 17HSD type 1 was seen. Immunohistochemical analysis indicated that this did not lead to significant enzyme expression, only faint staining for the enzyme protein being detected, mainly in uroepithelial cells. No significant correlation was found between any of the mRNAs analysed, but the data on 5alpha-reductase type 2 mRNA support the presence of an increased proportion of 5alpha-dihydrotesterone in the hyperplastic prostate. In cultured PC-3 prostatic cancer cells and in the transiently transfected human embryonic kidney 293 cells, 17HSD type 2 was found exclusively to convert 5alpha-dihydrotestosterone and testosterone into the less potent 17-keto compounds 5alpha-androstanedione and 4-androstenedione, respectively. We suggest that the 17HSD type 2 isoenzyme plays a part in the metabolic pathway, resulting in the inactivation of testosterone and 5alpha-dihydrotestosterone locally in the prostate. The enzyme expressed in the prostate could, therefore, protect cells from excessive androgen action.

Steroid-growth factor interaction in human prostate cancer. 2. Effects of transforming growth factors on androgen metabolism of prostate cancer cells

The ability of human prostate cancer cells to metabolize androgens was assessed through administration of physiological concentration (0.5-10 nM) of tritiated testosterone (T) as precursor and one-step analysis of both T degradation and products' formation by reverse-phase HPLC and on-line radioactive detection after either 24 h or 72 h incubation. Overall, different prostate cancer cells degraded T quite differently, favoring alternatively reductive or oxidative metabolic pathways. In particular, both LNCaP and DU145 cells retained high levels of unconverted T, with a limited production of androstenedione and its 17-keto derivatives and relatively high amounts of dihydrotestosterone (DHT) and 3 alpha-androstanediol (3 alpha-diol). In contrast, PC3 cells quickly degraded T and exhibited high formation rates of androstenedione and 17-keto metabolites, while neither dihydrotestosterone nor 3 alpha-diol were detected after short or longer incubation times. The effects of both TGF alpha (50 ng/mL) and TGF beta 1 (5 ng/mL) on rates and direction of T metabolism were also explored. In LNCaP cells TGF alpha induced a significant (P < 0.04) decrease of the reductive metabolism of T with a corresponding enhancement of the oxidative pathway (P < 0.002), while TGF beta 1 did not significantly affect T metabolism. On the other hand, both reductive and oxidative pathways were only partially influenced by either growth factor in DU145 and PC3 cells, although TGF alpha significantly raised 5 alpha-androstanedione formation and reduced androsterone production in DU145 cells. All the above evidence was confirmed at both 24 h and 72 h or using increasing doses of TGF alpha and TGF beta 1, a peak activity of 50 ng/mL and 5 ng/mL, respectively, being generally encountered. Overall, our data suggest that TGFs may have a role in the growth regulation of hormone-responsive prostate tumor cells through changes of the intracellular contents of biologically active androgen metabolites.

17 beta-Hydroxysteroid dehydrogenase activity in endometrial cancer cells: different metabolic pathways of estradiol in hormone-responsive and non-responsive intact cells

In this paper we report that two human long-term endometrial cancer cell lines, Ishikawa and HEC-1A, exhibit quite different abilities in metabolizing estrogens. As a matter of fact, incubation of Ishikawa cells with close-to-physiological concentrations of estradiol (E2) as precursor resulted in: (1) elevated formation (up to 90%) of E2-sulphate (E2-S), using lower precursor concentrations; (2) very limited conversion to estrone (E1) (< 10% at 24 h incubation), as either free or sulphate; and (3) low but consistent production of other estrogen derivatives, such as 2-hydroxy-estrogens and estriol. Conversely, scant amounts (if any) of E2-S were found in HEC-1A cells, while no detectable formation of other estrogen metabolites could be observed after 24 h. On the other hand, E1 production was significantly greater (nearly 60% at 24 h) than in Ishikawa cells, a large proportion of E1 (over 50% of the total) being formed after only 6 h incubation using time-course experiments. The hypothesis that E2 metabolism could be minor in Ishikawa cells as a consequence of the high rate of E2-S formation encountered is contradicted by the evidence that conversion to E1 also remains limited in the presence of much lower E2-S amounts, seen using higher molar concentrations of precursor. Overall, we observe that 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity diverges significantly in intact Ishikawa and HEC-1A endometrial cancer cells. This difference could not merely be accounted for by the diverse amounts of substrate (E2) available to the cells, nor may it be imputed to different levels of endogenous estrogens. It should rather be sought in different mechanisms controlling 17 beta-HSD activity or, alternatively, in the presence of distinct isoenzymes in the two different cell types.

Testosterone metabolism in primary cultures of human prostate epithelial cells and fibroblasts

We compare testosterone (T) metabolism in primary cultures of epithelial cells and fibroblasts separated from benign prostate hypertrophy (BPH) and prostate cancer tissues. In all cultures, androstenedione (delta 4) formed by oxidation of T by 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) represented 80% of the metabolites recovered. The amounts of 5 alpha-dihydrotestosterone (DHT), formed by reduction of T by 5 alpha-reductase (5 alpha-R), were small: 5 and 2% (BPH) and 8 and 15% (adenocarcinoma) for epithelial cells and fibroblasts, respectively. Northern blot analysis of total RNA from epithelial cells (BPH or adenocarcinoma) attributed the reductive activity to the 5 alpha-reductase type 1 isozyme and oxidative activity to the 17 beta-HSD type 2. In cancer fibroblasts, only little 17 beta-HSD type 2 mRNA was detected. The 5 alpha-reductase inhibitors, 4-MA (17 beta-(N,N-diethyl)carbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one) and finasteride, inhibited DHT formation with a preferential action of 4-MA on epithelial cells (BPH or adenocarcinoma) and of finasteride on fibroblasts from adenocarcinoma. Neither inhibitor acted on delta 4 formation. On the other hand, the lipido-sterol extract of Serenoa repens (LSESr, Permixon) inhibited the formation of all the T metabolites studied [IC50 S = 40 and 200 micrograms/ml (BPH) and 90 and 70 micrograms/ml (adenocarcinoma) in epithelial cells and fibroblasts, respectively]. These results have important therapeutic implications when selecting appropriate treatment options for BPH.