Isolation of 3 S androgen receptors from salt-resistant fractions and nuclear matrices of prostatic nuclei after mild trypsin digestion

Regulation of u-PA gene expression in human prostate cancer

u-PA contributes to CaP progression, especially in the metastatic androgen-insensitive state. In vitro, u-PA is expressed by androgen-insensitive, but not androgen-sensitive, CaP cell lines. We hypothesized that in androgen-sensitive CaP an activated ARE represses u-PA expression but in androgen-insensitive CaP this repression is lost and u-PA is upregulated through MAP kinase signaling pathways. To determine whether binding of the DHT-AR complex to AREs in the u-PA promoter region represses u-PA transcription in androgen-sensitive CaP, we studied 2 PC3 androgen-insensitive human CaP cell lines stably transfected with AR [PC3(AR)(2) and PC3(AR)(13)] and 1 mock-transfected cell line [PC3(M)]. In the presence of the synthetic androgen mibolerone, both PC3(AR)(2) and PC3(AR)(13), but not PC3(M), cells showed decreased u-PA expression as assayed by Western and Northern blotting. The AR inhibitor flutamide abrogated mibolerone's effect. Androgen regulation of a second gene, PSA, was also demonstrated in the PC3(AR)(2) cell line. To explore the pathway stimulating u-PA expression in CaP, we performed transient transfections in PC3(AR)(2) cells using u-PA promoter-regulated CAT reporter constructs. Compared to full-length u-PA promoter-CAT constructs, either deletion or mutation of the 5' AP-1 or PEA3 site reduced CAT expression. The location of androgen responsiveness in the u-PA promoter was not identified through the combination of promoter search and transient transfection assays, indicating that a more complicated mechanism is involved in the AR-mediated downmodulation of u-PA expression.

Subcellular trafficking of the nuclear receptor COUP-TF in the early embryonic cell cycle

The nuclear receptor SpCOUP-TF is the highly conserved sea urchin homologue of the COUP family of transcription factors. Previous results from our laboratory demonstrated that SpCOUP-TF transcripts are localized in the egg and asymmetrically distributed in the early embryonic blastomeres (A. Vlahou et al., 1996, Development 122, 521-526). To examine the subcellular localization of SpCOUP-TF protein, polyclonal antibodies were separately raised against the divergent N-terminus as well as the conserved DNA-binding and ligand-binding domains. Immunohistochemical analyses suggest that SpCOUP-TF is a maternal protein residing in the cytoplasm of the unfertilized egg. After fertilization, and as soon as the two-cell-stage embryo, most of the receptor translocates from the cytoplasm to the cell nuclei. During the rapid embryonic cell division, SpCOUP-TF was found to shuttle from the interphase nuclear periphery to the condensed chromosomes in mitosis, in a cell-cycle-dependent manner. In an attempt to confirm these observations, the subcellular localization of myc-tagged human COUP-TF I introduced into the sea urchin embryo by RNA injection of fertilized eggs was examined. The pattern of human COUP-TF I subcellular localization, detected with a monoclonal myc antibody, recapitulated the essential features described for the endogenous SpCOUP-TF trafficking. Replacement of the N-terminus of the human receptor with the unique sea urchin N-terminus enhanced its localization to the nuclear rim during interphase. Deletion of the DNA-binding domain of human COUP-TF I resulted in loss of all aspects of nuclear periphery and chromosomal localization. Taken together these data suggest that SpCOUP-TF transcriptional activity is keyed on a cell-cycle-dependent mechanism that regulates chromosomal protein traffic.

The nuclear matrix: a structural milieu for genomic function

While significant progress has been made in elucidating molecular properties of specific genes and their regulation, our understanding of how the whole genome is coordinated has lagged behind. To understand how the genome functions as a coordinated whole, we must understand how the nucleus is put together and functions as a whole. An important step in that direction occurred with the isolation and characterization of the nuclear matrix. Aside from the plethora of functional properties associated with these isolated nuclear structures, they have enabled the first direct examination and molecular cloning of specific nuclear matrix proteins. The isolated nuclear matrix can be used for providing an in vitro model for understanding nuclear matrix organization in whole cells. Recent development of high-resolution and three-dimensional approaches for visualizing domains of genomic organization and function in situ has provided corroborative evidence for the nuclear matrix as the site of organization for replication, transcription, and post-transcriptional processing. As more is learned about these in situ functional sites, appropriate experiments could be designed to test molecular mechanisms with the in vitro nuclear matrix systems. This is illustrated in this chapter by the studies of nuclear matrix-associated DNA replication which have evolved from biochemical studies of in vitro nuclear matrix systems toward three-dimensional computer image analysis of replication sites for individual genes.

Combination treatment in M1 prostate cancer

The treatment of advanced prostate cancer is based on hormone manipulation to eliminate the trophic effect of testosterone on sensitive androgen tissue of the tumor. In this study, we evaluated the efficacy of the partial androgen blockage versus the complete androgen blockage. One hundred, twenty-two patients were entered in this study and randomly were treated with buserelin alone or with buserelin and flutamide. The group that received buserelin was given cyproterone acetate (200 mg/day) during first 3 weeks of treatment to avoid "flare-up". During the follow-up (range 0-244 +/- 1 weeks), we evaluated 59 patients (61.4%) that had positive response and 37 patients (38.6%) that showed progressive disease: There were no statistically significant differences between the two treatment groups, not even in the evaluation of median time to response and of median time to treatment failure. In conclusion, the results emphasize that total androgenic blockage is as effective as a luteinizing hormone-releasing hormone analog used alone.

The nuclear matrix: a heuristic model for investigating genomic organization and function in the cell nucleus

Despite significant advances in deciphering the molecular events underlying genomic function, our understanding of these integrated processes inside the functioning cell nucleus has, until recently, met with only very limited success. A major conundrum has been the "layers of complexity" characteristic of all cell structure and function. To understand how the cell nucleus functions, we must also understand how the cell nucleus is put together and functions as a whole. The value of this neo-holistic approach is demonstrated by the enormous progress made in recent years in identifying a wide variety of nuclear functions associated with the nuclear matrix. In this article we summarize basic properties of in situ nuclear structure, isolated nuclear matrix systems, nuclear matrix-associated functions, and DNA replication in particular. Emphasis is placed on identifying current problems and directions of research in this field and illustrating the intrinsic heuristic value of this global approach to genomic organization and function.

Phosphorylation status of nuclear and cytosolic androgen receptors in the rat ventral prostate

We demonstrate that endogenous phosphatases are active in cytosolic and nuclear androgen receptor fractions from the rat ventral prostate. Under our androgen binding assay conditions, the effect of acid phosphatase inhibitors (sodium fluoride, tartaric acid, sodium orthovanadate) on the endogenous phosphatases could be correlated with an increase in dihydrotestosterone (DHT) binding to fractions of partially purified cytosolic androgen receptor. In contrast, tetramisole, an alkaline phosphatase inhibitor, did not alter the binding of DHT to the same receptor fraction. Immunoprecipitation of androgen receptor fractions with polyclonal anti-phosphotyrosine antibody resulted in the recovery of [3H]-DHT binding activity from nuclear receptor fractions and partially purified cytosolic receptor fractions prepared from 20- to 24-hr castrated rats. In control fractions depleted of androgen receptor, negligible levels of binding activity were recovered following immunoprecipitation with the antibody. Therefore, acid phosphatases may be acting on phosphotyrosyl residues of the androgen receptor, thus playing a role in the dephosphorylation and inactivation of the androgen receptor.

A domain model for eukaryotic DNA organization: a molecular basis for cell differentiation and chromosome evolution

A model for eukaryotic chromatin organization is presented in which the basic structural and functional unit is the DNA domain. This simple model predicts that both chromosome replication and cell type-specific control of gene expression depend on a combination of stable and dynamic DNA-nuclear matrix interactions. The model suggests that in eukaryotes, DNA regulatory processes are controlled mainly by the intranuclear compartmentalization of the specific DNA sequences, and that control of gene expression involves multiple steps of specific DNA-nuclear matrix interactions. Predictions of the model are tested using available biochemical, molecular and cell biological data. In addition, the domain model is discussed as a simple molecular mechanism to explain cell differentiation in multi-cellular organisms and to explain the evolution of eukaryotic genomes consisting mainly of repetitive sequences and "junk" DNA.

Binding of the androgen receptor to the nuclear matrix of human foreskin

The nuclear matrix (NM) is a salt and nuclease-resistant nuclear substructure. It is associated with active DNA transcription and has been shown to contain acceptor sites for steroid receptors in a number of specific target tissues. We have investigated the presence of acceptor sites for the androgen receptor (AR) in the NM of human newborn foreskin. The NM was prepared from the 800 g pellet by successive treatments with detergent, DNase and high salt extraction. It contained 13 +/- 7% of total proteins and 10 +/- 6% of total DNA. After extensive washing, the NM spheres were incubated in the presence of cytosol and [3H]methyltrienolone +/- 200-fold excess of unlabeled steroid. Maximal binding of the AR to NM was reached in 30 min and decreased slightly thereafter to reach an equilibrium which was maintained for 18 h. Binding was saturable. In the absence of AR, the steroid did not bind to NM. When Scatchard analysis was performed on cytosol previously incubated with NM, cytosolic binding capacity significantly decreased relative to preincubation values (3.6 +/- 1.9 to 1.3 +/- 1.2 fmol/mg protein, P less than 0.05, n = 6). In contrast, apparent binding affinity was not changed. 0.8 mg of NM protein could bind AR from 2.4 mg of cytosol protein. In conclusion, NM from human foreskin binds the AR with high affinity. This binding is rapid and is maintained for at least 18 h. This is consistent with a potential role of NM in the mechanism of action of androgens in their target tissues.

Androgen binding as evidenced by a whole cell assay system using cultured canine prostatic epithelial cells

The androgen receptor content in the prostate has been usually evaluated using subcellular fractions without taking into account cellular and functional heterogeneity of the gland. Using enriched populations of immature canine prostatic epithelial cells cultured in primary monolayers, a whole cell assay system was developed to measure androgen receptors. Tritiated dihydrotestosterone (DHT) and/or methyltrienolone (R1881) in serum-free medium were used as ligands and Triamcinolone acetonide (0.5 microM) was added to prevent the binding of R1881 to other types of receptors. The amount of radiolabelled ligand specifically bound to the cells was determined at equilibrium. Specific binding was proportional to the number of cells seeded. Scatchard analysis revealed the presence of at least two types of binding sites. The Kd for the high affinity binding site was 2 x 10(-9) M. Competition studies indicated that this component was specific for androgens; Methyltrienolone, Mibolerone and the antiandrogen RU 23908 were the most efficient competitors. They were followed by DHT, 5 alpha-androstane-3 alpha, 17 beta-diol, testosterone, estradiol and estrone. Progesterone, 5 alpha-androstane-3 beta, 17 beta-diol and epitestosterone were not inhibitors. The level of specific binding was 11.0 +/- 7.6 fmol of bound R1881 per 10(6) cells (n = 34) or 2075 +/- 1434 fmol per mg of DNA; these values correspond to an average of 6624 +/- 4577 sites per cell. Thus, using this whole cell assay system, specific and androgen receptors were detected in immature prostatic epithelial cells in culture. This assay will therefore be useful to study the interrelationship between androgen binding activity and specific cell functions.

Characterisation of a retinoic-acid-binding component from F9 embryonal-carcinoma-cell nuclei

When F9 murine-embryonal-carcinoma cells were incubated with all-trans-[3H]retinoic acid, approximately 10% of the tritium label taken up by the cells was recovered in the nuclei. Sonication or DNase I digestion followed by extraction with 0.6 M NaCl released 20-40% of the nuclear-associated retinoic acid. Analysis of these extracts showed that retinoic acid was bound to protein sedimenting at 4 S. This nuclear retinoic-acid-binding component bound all-trans- and 13-cis-retinoic acid with comparable affinity whereas retinol competed less efficiently for binding. These results suggest that F9 embryonal-carcinoma cells contain a nuclear binding protein for retinoic acid that is distinct from the cellular retinoic-acid-binding protein.

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.

Chemical demonstration of nuclear androgen receptor following affinity chromatography with immobilized ligands

With increasing purification of the androgen receptor from nuclei of rat ventral prostate, a receptor-like protein could be demonstrated by chemical staining with silver nitrate. After sonication and digestion of nuclei with micrococcal nuclease, the solubilized receptor was applied to a column of Matrex Gel Green A and eluted with a linear gradient of 0-2 M NaCl. Characterized by specific binding of dihydrotestosterone, this form of the receptor was also androgen dependent and yielded an apparent Mr of 33,000 when analyzed by polyacrylamide gel electrophoresis and silver nitrate staining. To facilitate recovery following chromatography, the receptor was precipitated with 0-40% ammonium sulfate. Analysis of the 15-fold enriched fraction by sucrose density-gradient centrifugation confirmed the presence of a 3S androgen-binding protein. About 200 ng of the precipitated protein was applied to a column of dihydrotestosterone-17 beta-succinyl agarose (ligand concentration, 0.25 mumol/ml). The fractions eluted with 50 microM dihydrotestosterone were electrophoresed and stained as before; again, the presence of a 33,000 Mr protein sensitive to castration was demonstrated. Alternatively, when the precipitated protein was fractionated by fast protein liquid chromatography utilizing a Superose 12 HR 10/30 column, the receptor coeluted with nuclear proteins in the 29,000-36,000 Mr range as determined both by retention time and electrophoresis. In combination, the above methods may be used to obtain a receptor protein purified to near homogeneity with a yield of 5-10%. The amount of receptor afforded by the purification sequence is small but nevertheless sufficient for chemical detection. We anticipate that with modification, the procedures may prove suitable for the recovery of nuclear androgen receptor on a preparative scale.

DNA and protein components of nuclear acceptor sites for androgen receptors in the rat prostate

Androgen receptor-acceptor complexes in nuclei from rat ventral prostates were cross-linked in situ with formaldehyde and partially purified using affinity chromatography. To isolate acceptor DNA, the cross-linked receptor-acceptor complexes in formaldehyde-treated chromatin samples were adsorbed to dihydrotestosterone-17 beta-succinyl agarose, eluted with 75 microM dihydrotestosterone-1% SDS, digested with proteinase K and extracted with phenol-chloroform. After 32P end-labelling and PAGE, this DNA contained two distinct bands of DNA (about 300 and 400 base pairs respectively) which were unique relative to the total prostatic DNA. As an alternative approach for characterizing acceptor DNA, the DNA in prostatic nuclei and cross-linked chromatin was labelled with 32P by nick translation and analysed in glycerol density gradients for associations with cross-linked androgen receptors. A symmetrical 7s peak of 32P-DNA with a small amount of coincident receptor was observed in the gradients after mild trypsin treatment. In the absence of trypsin treatment, both the cross-linked receptors and the labelled DNA sedimented to the bottom of the gradients. Isolation of acceptor proteins involved iodination of cross-linked chromatin with 125I and androgen affinity chromatography. A comparison of the relative efficiency of retention and elution of 125I-proteins from different affinity columns revealed that testosterone-17 beta-succinyl agarose was potentially most suitable for purification of acceptor proteins. After electrophoresis on SDS-polyacrylamide gels, the eluates from this type of affinity matrix were found to contain two major peaks of 125I-labelled proteins--one corresponding to a protein with a similar molecular weight as the nuclear androgen receptor (33,000 Da); the other having a molecular weight of 20,000 Da. While the precise identity of this latter entity is unknown, its enrichment and retention by the affinity gel implies that it is closely associated with the androgen receptor and may be a component of the acceptor sites.

The nuclear matrix is the site of glucocorticoid receptor complex action in the nucleus

Binding of highly purified glucocorticoid receptor complexes to nuclear matrix was evaluated. Extraction of purified nuclei with 2M potassium chloride and brief deoxyribonuclease digestion leaves a matrix structure containing 1% of nuclear DNA and 6-12% of nuclear proteins. The nuclear matrix retained two binding sites for receptor complexes, a high affinity, low capacity site and a low affinity, high capacity site. These sites have affinities and capacities consistent with those reported for binding of these complexes to intact nuclei. More extensive deoxyribonuclease treatment of the matrix resulted in a marked reduction of high affinity complex binding. Furthermore, the DNA binding form of the receptor complex but not the unactivated receptor complex bound to DNA fibers anchored to nuclear matrix as visualized by 18 nm gold particle receptor complexes. The data suggest that the nuclear matrix is the major site for coordinating glucocorticoid hormone action in the nucleus.

Correlations between prostate chromatin structure and transcriptional activity and acceptor site distribution

Androgen-receptor complexes are intimately involved in the maintenance of rat ventral prostate chromatin in a transcriptionally active structure. The presence or absence of androgens influenced the quantity of transcriptionally active chromatin and the distribution of acceptor sites for androgen-receptor complexes as probed by endonucleolytic cleavage. After castration, changes in the sedimentation rates of nucleosome oligomers were consistent with the absence of androgen-receptor complexes and elongating polyribonucleotide chains. These changes were accompanied by decreases in the ability of chromatin released under conditions of minimal nuclease digestion to bind androgen-receptor complexes and to support incorporation of RNA precursors responsive to androgenic stimulation. Saturation analyses of chromatin and nuclear fractions with partially purified androgen-receptor complexes revealed two affinity classes of acceptor sites. After castration, alterations in the intrachromatin distribution of acceptor sites were consistent with their redeployment into areas of decreased nuclease sensitivity, as previously shown for androgen-responsive genes.

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.

Age dependency of androgen and estrogen effects on incorporation of (3H)-thymidine by rat prostates in organ culture

Organ culture of the rat ventral prostate has been evaluated as a model for studying the biological effects of androgen agonists, androgen antagonists, and estrogens. Explants were cultured for up to 8 days, and incorporation of (3H)-thymidine and (3H)-uridine by the explants was measured. Dihydrotestosterone (DHT) increased the incorporation of (3H)-thymidine/microgram DNA when compared with the untreated controls at 4 days, P less than .05; and at 6 days, P less than .01. Enhanced uptake in explants from 6 to 8-week old rats also was observed with 10 nM estradiol (P less than .05) and 10 nM cyproterone acetate (P less than .02). DHT (10 nM) caused greater enhancement of uptake in explants from 3-week-old rats than in explants from 6- or 12-week-old rats. In contrast, estradiol (E2) increased incorporation only in prostates from the 6-week-old rats. Since both DHT and E2 can enhance (3H)-thymidine uptake even though they are associated with strikingly different effects on prostate morphology, it suggests that their effects on (3H)-thymidine incorporation are mediated by different cells.

Binding of the glucocorticoid receptor complex to the nucleosomal core in the P1798 mouse lymphosarcoma

Binding of the glucocorticoid receptor complex to nucleosomes has been studied using the mouse P1798 lymphosarcoma. Cells were incubated with [3H]triamcinolone acetonide (TA), and nuclei prepared and digested with 3 different concentrations of micrococcal nuclease. After fractionation with EDTA and NaCl, it was observed that [3H]TA bound with similar specific radioactivity to mononucleosomes containing both core and linker DNA, of 183 +/- 5, and 168 +/- 4 base pair lengths, respectively, as well as to core size DNA, of 148 +/- 3 base pair length, suggesting that the glucocorticoid receptor bound to the core portion of the nucleosome. Steroid binding was found to be associated with regions of the nucleosome that were depleted in histone H1 and enriched in high mobility group (HMG) proteins 1 and 2; only negligible binding was noted in nucleosomes enriched in histone H1 and depleted in HMG proteins. In addition to binding to core nucleosomes, the glucocorticoid receptor complex was also shown to bind to a fraction sedimenting at 5-6 S on sucrose gradients characterized by subnucleosome and mononucleosome size DNA, as well as by core histones. While binding of the steroid receptor complex to linker regions of the nucleosome cannot be ruled out, this data would appear to present the first concrete evidence that glucocorticoid binding, at least in the P1798 lymphosarcoma, is to core nucleosomes. Some caution in interpretation of the results is indicated, however, on 2 points: (1) receptor redistribution during nuclease digestion cannot be ruled out; (2) only the binding of a small proportion of the steroid receptor complex may be physiologically relevant.

A subset of non-histone nuclear proteins reversibly stabilized by the sulfhydryl cross-linking reagent tetrathionate. Polypeptides of the internal nuclear matrix

When rat liver nuclei are isolated in the presence of the irreversible sulfhydryl-blocking reagent iodoacetamide, digested with DNase I and RNase A, and extracted with 1.6 M NaCl, nuclear envelope (NE) spheres depleted of intranuclear material, as analysed by thin-section electron microscopy, are obtained. Two-dimensional isoelectric focusing (IEF)/SDS-PAGE and non-equilibrium pH gradient electrophoresis (NEPHGE)/SDS-PAGE reveal that the predominant polypeptides are lamins A, B and C. Nuclei isolated in the absence of sulfhydryl blocking reagents yield salt- and nuclease-resistant structures which contain sparse but demonstrable intranuclear material. A number of non-histone polypeptides are seen in addition to the lamins. Nuclei treated with the sulfhydryl cross-linking reagent sodium tetrathionate (NaTT) yield, after exposure to nucleases and 1.6 M NaCl, nuclear matrix-like structures containing an extensive intranuclear network and components of the nucleolus in addition to the NE. Increased amounts of the non-lamin, non-histone polypeptides are recovered with these structures. Subsequent treatment of these NaTT-cross-linked structures with reducing agents in 1.0 M NaCl selectively solubilizes the intranuclear components but leaves the nuclear envelope apparently intact. The lamins remain sedimentable and are virtually absent from the soluble (intranuclear) material. Instead, the major solubilized polypeptides are (a) 68 and 63 kD polypeptides which migrate in the vicinity of lamins B and C, respectively, but are distinguishable from the lamins by immunoblotting and by uni-dimensional peptide mapping; (b) a series of basic 60-70 kD polypeptides (pI greater than 8.0) which are not recognized by anti-lamin antisera; (c) an acidic (pI 5.3) 38 kD polypeptide; and (d) a number of high molecular mass (greater than 100 kD) polypeptides. These observations not only suggest a convenient method for fractionating matrix structures from rat liver nuclei into biochemically and morphologically discrete components, but also identify a subset of major non-lamin, non-histone nuclear polypeptides (comprising approx. 20% of the total nuclear protein) whose intermolecular interactions can be reversibly stabilized apparently by intermolecular disulfide bond formation by NaTT.

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.