Androgen binding sites on nuclear matrix of normal and hyperplastic human prostate

Ageing and prostate: age-related changes in androgen receptors of epithelial cells from benign hypertrophic glands compared with cancer

Total and nuclear androgen receptors (AR) were studied from epithelial cells in internal and external prostatic zones in 51- to 86-year-old individuals with benign prostatic hyperplasia (BPH) (n = 68) and prostatic cancer (n = 9). We focussed on the role played by androgens on those processes, despite the fact that at these ages, its secretion has normally decreased. In BPH, the nuclear AR do not change, but total measured androgen receptors rise with age (r = 0.5, P < 0.01). Total or nuclear AR do not correlate with gland volume, despite its increase with age (r = 0.8, P < 0.05). In prostates less than 180 cc in volume, there is a significant correlation between size, serum total testosterone level (r = 0.53, P < 0.05) and prostatic specific antigen (PSA) (r = 0.63, P < 0.05). The amount of nuclear AR in cells from the external zone (infiltrated by cancer or healthy) is two times greater than in those from the internal region. Total receptor content of the external zone cells is also high, but the sample is too small to demonstrate an age dependence. The results suggest that ageing is accompanied by an accumulation of non-nuclear AR in the cytosol, that does not play a role in the development of BPH because the amount of nuclear receptors remains unaltered. The enrichment in nuclear receptors of the external zone cells, independently of the presence of cancer, points to a greater androgen dependence in these cells than in cells of the internal region.

Androgen receptor mRNA in the rat ovary and uterus

The distribution of androgen receptor messenger RNA (ARmRNA) in the reproductive tissues of adult rats was examined by Northern blot analysis and in situ hybridization using ARcRNA probes corresponding to the androgen binding domain of the receptor. About 10-kilobase rat ARmRNA was observed in all tissues examined in the Northern blot analysis. The amount of ARmRNA in the ovary, uterus and testis was less than that in the prostate. In the in situ hybridization study, extensive labeling was observed in the theca cells of the ovary (proestrous) and the endometrium and endometrial glands of the uterus (proestrous). Moderate labeling was observed in the granulosa cells and stromal cells of the ovary and in the myometrium of the uterus. These results were largely in agreement with the distribution of AR previously reported by ligand binding studies. This present in situ hybridization study may provide a useful tool for the analysis of the regional regulation of AR synthesis in the rat female reproductive tissues.

Demonstration of DNA binding factors interacting with a fragment of the canine prostate arginine esterase gene promoter

We have studied, by the gel mobility shift assay, the interaction of DNA binding proteins with a fragment of the proximal promoter (from nucleotides -177 to -47) of the androgen-regulated canine prostate arginine esterase gene. Several shifted bands were obtained using nuclear extracts from various tissues. In the case of the prostate, the intensity of some of the shifted bands was decreased or increased when the extracts were prepared from animals that had been castrated 12 days earlier. Several of the DNA-protein complexes could be assigned to an interaction with part or all of the sequence GGGGGTGGGGG from-124 to -114. We also obtained evidence for the presence of protein(s) interacting with an Sp1 motif present in the same fragment. These results suggest that some ubiquitous factors different from the androgen receptors could be involved in the regulation of the arginine esterase gene.

Nuclear structure and the three-dimensional organization of DNA

The organization of DNA within the nucleus has been demonstrated to be both cell and tissue specific and is arranged in a non-random fashion in both sperm and somatic cells. Nuclear structure has a pivotal role in this three-dimensional organization of DNA and RNA and contributes as well to forming fixed organizing sites for nuclear functions, such as DNA replication, transcription, and RNA processing. In sperm, DNA is also organized in a specific fashion by the nuclear matrix and DNA-protamine interactions. Within somatic cells, the nuclear matrix provides a three-dimensional framework for the tissue specific regulation of genes by directed interaction with transcriptional activators. This differential organization of the DNA by the nuclear matrix, in a tissue specific manner, contributes to tissue specific gene expression. The nuclear matrix is the first link from the DNA to the entire tissue matrix system and provides a direct structural linkage to the cytomatrix and extracellular matrix. In summary, the tissue matrix serves as a dynamic structural framework for the cell which interacts to organize and process spatial and temporal information to coordinate cellular functions and gene expression. The tissue matrix provides a structural system for integrating form and function.

Androgen receptor assays in specimens of prostatic tissue obtained by transurethral resection and transvesical adenomectomy

The main goal of this study was to ascertain whether routine transurethral resection (TUR) of prostate may provide useful material for the evaluation of androgen receptor (AR) status. At the same time, either intracellular distribution of binding affinity and capacity of receptor molecules were particularly taken into account. Based on our previous findings in breast and endometrial cancer, we suggest that a "functional" receptor status may correspond to the presence of type I (high affinity, low capacity) AR in both soluble and nuclear fractions. However, the precise significance of type II (lower affinity, higher capacity) binding sites remains to be clarified. Ten samples of large prostatic adenomas, obtained by transvesical adenomectomy (TVA), were compared with ten parallel specimens obtained by an in vitro TUR, whereby a pure cutting current was used. The AR assay was carried out with a standard competition method using tritiated mibolerone as the radioligand and Scatchard analysis for data processing. No significant difference between the TUR and TVA groups emerged concerning type I AR content of soluble, nuclear or soluble together with nuclear fractions; this was also true when the results were expressed either as fmol/ml homogenate or as fmol/mg DNA. Similarly, concentrations of type II AR in TVA and TUR samples did not differ significantly in either cell compartment, although they were widely scattered, especially in the soluble fraction. In the light of our findings, it is suggested that TUR specimens represent suitable material for receptor studies, provided that only cutting current is employed and that the use of coagulation current, to control bleeding from the prostatic bed, is confined to the final step of the TUR procedure.

Human hepatocellular carcinoma tumor xenografts. Their androgen-receptor status and growth responses to castration

Castrated or sham-operated male athymic mice were inoculated with cells from the human hepatocellular carcinoma cell line PLC/PRF/5. There were no significant differences between the two groups with respect to the number of animals developing tumors, the time to tumor development, or the subsequent rate of increase in either tumor base area or mouse serum alpha-fetoprotein concentration. Androgen receptors were assayed in nuclei obtained from three separate liver cancer cell lines and from normal adult human liver. Similar concentrations, ranging from 235 to 550 fmol/mg DNA, of nuclear androgen receptors were detected in all tissues. Low percentages of androgen receptors were retained on DNA-cellulose. Although the presence of receptors implies the potential for metabolic effects of androgens in normal and malignant liver, our in vivo studies suggest that castration does not alter significantly the growth of liver cancer xenografts in athymic mice.

Androgen receptor binding activity in meningiomas

Analyses of androgen receptor binding activity in 54 intracranial, intraspinal, and metastatic meningiomas were performed with a specific radioligand binding technique using [3H]R 1881 as radioligand. [3H]R 5020 was used for the concurrent determination of progesterone receptor binding activity. Moderate concentrations of androgen receptors (33.4 +/- 5.4 fmol/mg protein) were detected in 35 (65%), whereas high levels of progesterone binding components (236 +/- 35 fmol/mg protein) were demonstrated in 48 (89%) tumors. The androgen receptor binding activity was positively correlated with the progesterone receptor binding activity (rs = 0.38, p less than 0.05). This relationship is suggestive of an androgen regulation of the progesterone receptor via the androgen receptor system. The presence of androgen and progesterone receptors in a large proportion of meningiomas, and the tendency for a dependence of androgen receptor and progesterone receptor binding activity on the histological subtype could have implications for tumor therapy.

Estrogen receptor immunoreactivity in meningiomas. Comparison with the binding activity of estrogen, progesterone, and androgen receptors

Estrogen receptor (ER) analysis was performed in 70 meningioma samples by means of two assays: an enzyme immunoassay that used monoclonal antibodies against human ER protein (estrophilin), and a sensitive radioligand binding assay that used iodine-125-labeled estradiol as the radioligand. Low levels of ER immunoreactivity were found in tumors from 51% of patients, whereas ER binding activity was demonstrated in 40% of the meningiomas examined. In eight (11%) of the tissue samples, multiple binding sites for estradiol were observed. The immunoreactive binding sites corresponded to those of the classic high-affinity ER. In ligand binding studies, however, measurement of classic ER was considerably influenced by a second low-affinity high-capacity estrogen binding component, even at low ligand concentrations. Binding activity of the progesterone receptor (PR) and androgen receptor (AR) was determined concurrently using 17 alpha-methyl-3H-promegestone (3H-R 5020) and 17 alpha-methyl-3H-trienolone (3H-R 1881), a synthetic gestagen and androgen, respectively. High concentrations of PR were detected in 53 (76%) of the tumors, whereas a moderate number of AR binding sites were demonstrated in 33 (47%) of the tumors. A positive correlation between ER immunoreactivity and AR binding activity is suggestive of estrogen regulation of AR via the ER system. The presence of gonadal steroid receptors in a large proportion of meningiomas and the tendency toward a dependence of receptor concentrations on the histological subtype of the meningioma could have implications for tumor therapy.

Gonadal steroid receptors in meningiomas

Oestrogen receptor (ER) analysis was performed in 70 meningiomas with an enzyme immunoassay, using monoclonal antibodies against human oestrogen receptor protein (oestrophilin) and with a sensitive radioligand binding assay, using 125I-oestradiol as radioligand. Low levels of ER immunoreactivity were found in tumours from 51% of patients, whereas ER binding activity was demonstrated in 40% of the meningiomas examined. In 8 (11%) tissue samples multiple binding sites for oestradiol were observed. The immunoreactive binding sites corresponded to the classical, high-affinity ER. In ligand binding studies, however, measurement of classical ER was considerably influenced by a second low-affinity, high-capacity oestrogen binding component even at low ligand concentrations. 3H-methylpromegestone and 3H-methyltrienolone, a synthetic gestagen and androgen, were used for concurrent determination of the progesterone receptor (PR) and androgen receptor (AR) binding activity. High concentrations of PR were detected in 53 (76%), whereas moderate levels of AR binding sites were demonstrated in 33 (47%) tumours. A positive correlation between ER immunoreactivity and AR binding activity is indicative for an oestrogen regulation of AR via the ER system. The presence of gonadal steroid receptors in a large proportion of meningiomas and the tendency for a dependence of receptor concentrations on the histological subtype could have implications for tumour therapy.

Steroid hormone receptor localization in the nuclear matrix: interaction with acceptor sites

The nuclear matrix is a conceptually attractive candidate for the site in the nucleus where steroid hormone-receptor complexes might interact to modulate DNA structure and function. We have demonstrated that in sex steroid target tissues a major proportion (50-100%) of the high affinity and steroid-specific receptors that become associated with the nucleus following hormonal stimulation are localized in the nuclear matrix. Direct cell-free binding assays confirm that this localization is due to the presence of specific acceptor sites in the matrix to which steroid-receptor complexes bind with high affinity and tissue specificity, and is not the result of spurious binding. The nuclear matrix appears to be a major site of hormone receptor binding in the nucleus, and this situation is consistent with the known ability of steroid hormones to stimulate gene transcription, a process which also appears to occur in association with the nuclear matrix.

Applicability of nuclear androgen receptor quantification to human prostatic adenocarcinoma

It has been proposed that concentrations of nuclear androgen receptor may be predictive of tumor hormone dependence in cases of advanced human prostatic cancer. We have investigated the ability of this receptor population to reflect patient prognosis during endocrine therapy in 12 cases of stage D disease. KCl-extractable, nuclear matrix-bound and total nuclear androgen receptor concentrations showed a significant positive correlation with duration of patient survival (p less than 0.05) while cytosolic and total cellular androgen receptor concentrations were not significantly correlated with survival. However, use of selected threshold concentrations of receptors revealed that only cytosolic, nuclear KCl-extractable and total cellular receptors could significantly differentiate long-term and short-term survivors. Even given the small number of patients studied, the potential use of this androgen receptor assay as an index of both tumor hormone-dependence and patient prognosis was evident. Therefore, in order to make these androgen receptor assays more applicable, we attempted to simplify the methods for use on readily available tissues. Similar amounts of nuclear androgen binding were observed in crude and purified nuclear pellets, in nuclei treated with DNase and KCl in differing orders or in nuclei from tissue homogenized using glass or Polytron homogenization procedures. More importantly, nuclear androgen receptor concentrations in specimens of prostatic cancer or benign hyperplasia taken by needle biopsy or transurethral resection involving electrocautery did not differ from those of parallel specimens taken by Thompson cold punch. Simplified nuclear androgen receptor assays of needle biopsy or electrocautery specimens are accurate and should prove clinically applicable.

Association states of androgen receptors in nuclei of human benign hypertrophic prostate

Androgen receptors (AR) were quantified in nuclei purified from unfractionated benign hypertrophic prostate (bph) tissue and from separated epithelium and stroma from bph specimens. Both epithelial and stromal cell nuclei contained AR, although concentrations in epithelial cell nuclei were higher and more variable. Variations in AR levels in epithelial cell nuclei reflected variations in unfractionated-tissue nuclei. Nuclear AR were further characterized regarding extractability with or resistance to 0.6 mol/lKCl and micrococcal nuclease. Nuclei from unfractionated tissue, epithelium, and stroma contained populations of AR susceptible and refractory to solubilization with KC1 and nuclease. Nuclease- and salt-sensitive populations of AR were similar numerically. The observed variability in epithelial cell nuclear AR was attributable to a wide range of solubilizable AR. Nuclease-digestion profiles and sedimentation analyses revealed that this wide range was not due to AR associated with soluble chromatin oligomers but to AR not detectably associated with other nuclear components. In contrast, AR in stromal cell nuclei was predominantly resistant to KC1 and nuclease, and variability in total nuclear AR concentration was due to variation in the nonextractable population.

Relationship between concentrations of extractable and matrix-bound nuclear androgen receptor and clinical response to endocrine therapy for prostatic adenocarcinoma

The relationship between androgen receptor concentrations and clinical response to endocrine therapy for prostatic adenocarcinoma was investigated for 13 stage D patients. Both cytoplasmic and nuclear-androgen receptors were quantified. For nuclear androgen receptor, nuclei were isolated and treated with high ionic strength buffer (0.6 M KCl) to yield a KCl-extractable fraction; the nuclei were then treated with DNase I to yield nuclear matrices. Electron microscopy confirmed the relative nuclear purity and revealed matrix morphology. An hydroxylapatite binding assay and methyltrienolone (R1881) were used to quantify androgen receptor in cytosol, the KCl-extract and matrix preparations. Following 6 months of hormonal therapy, the clinical status of patients was re-evaluated and the patients were grouped according to disease response. The androgen receptor data obtained prior to therapy were compared for the disease response groups. The mean concentrations of cytoplasmic androgen receptor, KCl-extractable nuclear androgen receptor and nuclear matrix-bound androgen receptor, respectively, in those patients with disease progression or death (no. = 6), were 671 +/- 232, 45 +/- 17 and 119 +/- 34 fmol. per gm. of tissue +/- S.E.M., and for those with disease regression or stabilization (no. = 7), 1427 +/- 435, 193 +/- 53 and 611 +/- 92 fmol. per gm. of tissue +/- S.E.M. While cytoplasmic androgen receptor concentrations were not related to clinical status, both extractable and matrix-bound nuclear androgen receptor concentrations were significantly higher in the group which responded to hormonal therapy. These results suggest that nuclear-extractable and nonextractable androgen receptor concentrations are useful indices for the prediction of hormone-dependence of prostatic cancer.