Expression of 5 alpha-reductase in bacteria as a trp E fusion protein and its use in the production of antibodies for immunocytochemical localization of 5 alpha-reductase

A cDNA encoding a full-length rat 5 alpha-reductase was isolated using female rat liver mRNA and the polymerase chain reaction, and fused to the Escherichia coli trp E gene in a pATH expression vector. The trp E-5 alpha-reductase fusion protein expressed in bacteria and a synthetic oligopeptide corresponding to the C-terminus of rat 5 alpha-reductase were used as antigens to produce rabbit polyclonal antibodies to 5 alpha-reductase. Antibodies to the 5 alpha-reductase portion of the fusion protein and to the peptide were purified by affinity chromatography. Antibodies against the 5 alpha-reductase fusion protein reacted with a single component of rat liver microsomes with M(r) 26,000 on Western blots, consistent with the size of 5 alpha-reductase predicted from its cDNA, and with a M(r) 23,000 component on Western blots of detergent extracts of rat ventral prostate nuclei; other rat ventral prostate cellular fractions (mitochondrial, microsomal, cytosol) bound little or no antibody. Antibody against the synthetic peptide reacted with a M(r) 26,000 component of rat liver microsomes as well as with several components in various cellular fractions of rat ventral prostate. With anti-5 alpha-reductase fusion protein antibodies, specific immunocytochemical staining was observed in the epithelial cell nuclei of the rat ventral prostate, seminal vesicle, epididymis and other accessory sex glands. This nuclear staining was specific, since antibodies from non-immunized rabbits did not give nuclear staining and preincubation of the anti-5 alpha-reductase fusion protein antibodies with the trp E-5 alpha-reductase fusion protein eliminated nuclear staining. Incubation of antibodies with trp E (without the 5 alpha-reductase fusion) had no effect on nuclear staining. Specific staining was not detected in the cytoplasm of these epithelial cells. Little or no specific staining was observed in stromal cells in these rat tissues. Human prostate was also immunocytochemically stained with this antibody. Specific staining was found in both epithelial and stromal cell nuclei.

The androgen receptor status of neuroendocrine cells in human benign and malignant prostatic tissue

Neuroendocrine (NE) cells containing neurosecretory granules, rich in various peptide hormones and biogenic amines, are components of the human prostate epithelium and prostatic adenocarcinomas. Neuroendocrine differentiation in prostatic adenocarcinomas has been associated with a poor prognosis and, following androgen withdrawal therapy, tumor cell populations have been observed to become enriched with NE cells. We assessed androgen receptor (AR) expression in NE cells in benign and malignant prostatic tissue using double-labeling immunocytochemistry with validated monoclonal antibodies to the AR and to chromogranin A (a generic NE marker). Neuroendocrine cells in benign and malignant prostatic tissue generally showed nuclear staining with AR. Some distinct AR-negative nuclei were observed in normal NE cells. In prostatic adenocarcinomas with extensive NE differentiation, a subpopulation of AR-negative NE cells was demonstrated. In conclusion, benign and malignant prostatic tissue contain both AR-positive and AR-negative NE cells that may have significance in regards to androgen-independent tumor growth and tumor progression.

Immunocytochemical localization of androgen receptors in human skin using monoclonal antibodies against the androgen receptor

Androgen receptors were localized in cryostat sections of human skin using monoclonal antibodies to the human androgen receptor. Bound antibodies were detected using biotinylated rabbit anti-rat IgG, peroxidase-conjugated streptavidin, and diaminobenzidine as chromogen. In the neonatal foreskin, antibody to androgen receptor bound to keratinocytes in the epidermis and to fibroblasts and vascular endothelial cells in the dermis. Immunohistochemical staining was stronger in nuclei than in cytoplasm. This staining was specific, because there was no significant staining when antibody to the androgen receptor was replaced with IgG from nonimmunized rats or with buffer, or when antibody to androgen receptor was incubated, prior to immunostaining, with a trp E-human androgen-receptor fusion protein used as immunogen. Incubation of androgen receptor antibody with trp E alone did not affect staining. Androgen-receptor antibody also bound to keratinocytes, fibroblasts, and endothelial cells in skin from adult men and women. Skin from the scalp, nose, lip, back, and chest gave positive staining for androgen receptor. Antibody to androgen receptor also bound to the coil and ductal cells of eccrine glands, external root sheath of hair follicles, epithelium in the hair bulb, dermal papilla cells, and sebocytes. There was no significant binding to adipocytes, collagen, or stratum corneum. These results show that androgen receptor is present in cells that are known to be targets for androgens and also in cells in which the biologic effects of androgens are yet to be characterized.

Immunohistochemical localization of androgen receptor in the human endometrium, decidua, placenta and pathological conditions of the endometrium

The immunohistochemical localization of the androgen receptor in the human endometrium at various stages of the menstrual cycle and post-menopausal period, in decidua and placenta of early pregnancy, and in several pathological conditions of the endometrium has been investigated. At any phase of the menstrual cycle, both endometrial glandular cells and endometrial stromal cells showed positive nuclear staining. Endometrial stromal cells of the functional layer showed stronger staining than those of the basal layer, but endometrial glandular cells of both layers showed the same staining intensity. There was little staining in myometrium. Even after menopause, endometrial glandular and stromal cells showed the same staining pattern as the basal layer of pre-menopausal endometrium and the staining intensity of endometrial stromal cells was weak. In decidua and placenta of early pregnancy, decidual and trophoblastic cells showed positive staining and there was no staining in the stromal cells of placenta. The expression of the androgen receptor was also detected in adenomyosis, endometriosis and endometrial carcinoma. Although the proliferation and differentiation of endometrium are mediated mainly by oestrogen and progesterone receptors, the androgen receptor may play some role in modulating these changes. These results suggest that it may be involved in both physiological and pathological changes of the endometrium.

Inhibition of steroid 5 alpha-reductase by specific aliphatic unsaturated fatty acids

Human or rat microsomal 5 alpha-reductase activity, as measured by enzymic conversion of testosterone into 5 alpha-dihydrotestosterone or by binding of a competitive inhibitor, [3H]17 beta-NN-diethulcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one ([3H]4-MA) to the reductase, is inhibited by low concentrations (less than 10 microM) of certain polyunsaturated fatty acids. The relative inhibitory potencies of unsaturated fatty acids are, in decreasing order: gamma-linolenic acid greater than cis-4,7,10,13,16,19-docosahexaenoic acid = cis-6,9,12,15-octatetraenoic acid = arachidonic acid = alpha-linolenic acid greater than linoleic acid greater than palmitoleic acid greater than oleic acid greater than myristoleic acid. Other unsaturated fatty acids such as undecylenic acid, erucic acid and nervonic acid, are inactive. The methyl esters and alcohol analogues of these compounds, glycerols, phospholipids, saturated fatty acids, retinoids and carotenes were inactive even at 0.2 mM. The results of the binding assay and the enzymic assay correlated well except for elaidic acid and linolelaidic acid, the trans isomers of oleic acid and linoleic acid respectively, which were much less active than their cis isomers in the binding assay but were as potent in the enzymic assay. gamma-Linolenic acid had no effect on the activities of two other rat liver microsomal enzymes: NADH:menadione reductase and glucuronosyl transferase. gamma-Linolenic acid, the most potent inhibitor tested, decreased the Vmax. and increased Km values of substrates, NADPH and testosterone, and promoted dissociation of [3H]4-MA from the microsomal reductase. gamma-Linolenic acid, but not the corresponding saturated fatty acid (stearic acid), inhibited the 5 alpha-reductase activity, but not the 17 beta-dehydrogenase activity, of human prostate cancer cells in culture. These results suggest that unsaturated fatty acids may play an important role in regulating androgen action in target cells.

Immunohistochemical localization of androgen receptor in the human ovary throughout the menstrual cycle in relation to oestrogen and progesterone receptor expression

In order to elucidate the role of androgen receptors (AR) in human ovaries, we examined their immunohistochemical localization, in comparison with oestrogen receptors (ER) and progesterone receptors (PR), at various stages of the menstrual cycle and follicular development. Primordial and primary follicles did not express AR. In granulosa and thecal cells of secondary follicles there was weak nuclear staining for AR. Granulosa cells of dominant follicles showed moderate nuclear staining for AR, which was stronger than that in thecal cells. In the luteal phase, the staining intensity for AR was strongest in the early luteal phase just after ovulation and declined gradually thereafter. Thecal cells of atretic follicles showed moderate nuclear staining for AR, which was a little stronger than that in dominant follicles. There was weak nuclear staining for AR in stromal cells surrounding follicles. Though there was variation in the staining intensity, AR were present at almost all stages of the menstrual cycle. There is a possibility that androgens, mediated by AR, may play an essential role in follicular growth and maturation, atresia and luteinization as autocrine or paracrine agents.

Substitution of aspartic acid-686 by histidine or asparagine in the human androgen receptor leads to a functionally inactive protein with altered hormone-binding characteristics

We have identified two different single nucleotide alterations in codon 686 (GAC; aspartic acid) in exon 4 of the human androgen receptor gene in three unrelated families with the complete form of androgen insensitivity. One mutation (G----C) results in an aspartic acid----histidine substitution (with 15-20% of wild-type androgen-binding capacity), whereas the other mutation (G----A) leads to an aspartic acid----asparagine substitution (with normal androgen-binding capacity, but a rapidly dissociating ligand-receptor complex). The mutations eliminate a Hinfl restriction site. Screening for the loss of the Hinfl site in both families with the Asp----Asn mutation resulted in the recognition of heterozygous carriers in successive generations of each. Both mutant androgen receptors were generated in vitro and transiently expressed in COS and HeLa cells. The receptor proteins produced had the same altered binding characteristics as those measured in fibroblasts from the affected subjects. R1881-activated transcription of a GRE-tk-CAT reporter gene construct was strongly diminished by both mutant receptors and was only partially restored using a 100-fold higher concentration of ligand compared with wild-type receptor. Thus, aspartic acid-686 appears essential for normal androgen receptor function. Substitution of this amino acid residue, by either histidine or asparagine, results in androgen insensitivity and lack of androgen-dependent male sexual differentiation.

Regulation of androgen receptor mRNA in rat Sertoli and peritubular cells

Regulation of 9.5-kb androgen receptor mRNA concentrations in Sertoli and peritubular cells from 20-day-old rats was studied by Northern blot analysis. Treatment of cells in vitro for 1-7 days with 300 ng/ml FSH increased androgen receptor mRNA up to 4-fold in Sertoli cells but not in peritubular cells. Testosterone (100 ng/ml) had no effect or slightly decreased androgen receptor mRNA in Sertoli and peritubular cells. Androgen receptor mRNA concentrations in Sertoli and peritubular cells from rats killed 15 days after hypophysectomy were elevated 4-5-fold over those in cells from intact rats. The androgen receptor mRNA concentration was decreased in both Sertoli and peritubular cells isolated from hypophysectomized animals treated with 500 micrograms/day testosterone propionate in vivo and subsequently with 100 ng/ml testosterone in vitro. FSH treatment (100 micrograms/day in vivo, followed by 300 ng/ml in vitro) did not increase androgen receptor mRNA over that in cells from hypophysectomized controls but rather decreased its concentration to varying degrees in Sertoli and peritubular cells. The rise in androgen receptor mRNA in both Sertoli and peritubular cells isolated from hypophysectomized animals is attributable, at least in part, to the absence of the inhibitory influence of testosterone. Other data in the literature suggest positive regulation of Sertoli cell androgen receptor protein by FSH and androgens. Consequently, complex mechanisms involving transcriptional, translational, and post-translational regulation probably control androgen receptor concentrations in the cells of the rat seminiferous tubule.

Anti-5 alpha-reductase autoantibodies in the serum of patients with prostatic cancer

Human sera were tested for their ability to inhibit 5 alpha-reductase binding of a potent inhibitor of the enzyme. Thirty one of 227 serum samples from patients diagnosed or suspected of prostatic cancer had a significant inhibitory activity, whereas 128 serum samples from other patients were inactive. The majority of the inhibitory activity was in the IgG fraction purified by chromatography on a protein A-Sepharose affinity column and an anti-human IgG-agarose column. IgG fractions from non-inhibitory sera were inactive. Inhibitory IgG also inhibited the enzymatic activity of microsomal 5 alpha-reductase from liver, ventral prostate and preputial gland of rat, and liver, prostate, and facial skin of human. The inhibitory IgG had no effect on NADH-menadione reductase or 17 beta-hydroxysteroid dehydrogenase. These results suggest that 5 alpha-reductase autoantibodies are present in the blood of some prostatic cancer patients.

DNA linkage analysis and studies of the androgen receptor gene in a large kindred with complete androgen insensitivity

DNA linkage analysis of the X chromosome and studies with cDNA probes specific for the androgen receptor gene were performed on the largest known kindred with the syndrome of complete androgen insensitivity. The affected subjects (XY) have absent binding of dihydrotestosterone to the androgen receptor (the receptor negative form of androgen insensitivity). In this kindred there was maternal transmission of the gene, with all affected males expressing complete genital feminization. Linkage analysis studies were conducted with two DNA probes, DXS1 and PGK1, localized to the Xq11-Xq13 region of the long arm of the X chromosome near the centromere. The results demonstrate linkage to the markers in the order of DXS1-(AR; PGK1), thus localizing the AR gene to an area between Xq11 and Xq13. Three cDNA probes that span various parts of the androgen receptor gene, including the DNA and steroid binding domain, were used to evaluate the androgen receptor gene in normal individuals, carrier mothers, and affected subjects. Identical restriction fragment patterns were found in all three groups studied. Thus the androgen receptor gene was present in affected subjects without detectable DNA polymorphism at the androgen binding domain. Therefore, despite complete absence of binding to the androgen receptor, the defect in the androgen receptor gene in this kindred is not the result of a gene deletion. The results point to a mutation or a small insertion/deletion as the probable cause of the syndrome.

Molecular cloning of new human TR2 receptors: a class of steroid receptor with multiple ligand-binding domains

Previously we isolated a new group of cDNA clones from human testis cDNA libraries which might code for new steroid receptors. The cDNA and predicted amino acid sequences of two of these receptors, named TR2-5 and TR2-7 receptors, were determined. We report here the nucleotide and deduced amino acid structures of two other receptors that we named TR2-9 and TR2-11 receptors. The calculated MW of TR2-5 receptor, TR2-7 receptor, TR2-9 receptor and TR2-11 receptor are 52,982, 20,528, 50,849 and 67,223 respectively, which match well with the apparent MW of in vitro translated products. The 26 amino acids involved in the formation of "Zn-fingers" are conserved. The ligand-binding domain of TR2-9 receptor is 16 amino acids shorter and has 3 different amino acids compared with TR2-5 receptor. The TR2-11 receptor has a ligand-binding domain which is longer and quite different compared with the other TR2 receptors. The multiple ligand-binding domains of TR2 receptor could be the products of different genes or may be due to RNA splicing errors. So far, we have failed to find binding activity with any known steroid hormone; this promotes the possibility that an unidentified steroid hormone may be involved.

Prostate androgen receptor: immunohistological localization and mRNA characterization

Four androgen receptor (AR) specific monoclonal antibodies were used for the immunohistochemical localization of AR in the human prostate tissue. The prostate tissue consisted of alveoli embedded in fibromuscular stroma and lined with a single layer of columnar secretory epithelial cells. The immunoreactive ARs were found predominantly in the nuclei of epithelial cell, suggesting ARs, like estrogen receptors and progesterone receptors, are mainly nuclear proteins. Northern blot hybridization showed that AR mRNA is about 9 kilobases (kb) and relative abundant in the androgen-sensitive organs, such as ventral prostate, dorsolateral prostate and seminal vesicle.

Steroid receptor recycling and interaction of receptor with RNA

Steroid receptors, such as the androgen receptor from the rat ventral prostate, are involved in a recycling process as part of the mechanism by which steroids affect target tissues. Recycling of steroid-receptor complexes may involve interaction of receptors with RNA. Evidence for RNA-receptor complexes in various cells and tissues has been presented, and it has been shown that the ability of RNA to interact with steroid-receptor complexes is dependent on the composition of the RNA. As part of our investigations on the role of RNA in steroid-receptor recycling, we have studied the effects of actinomycin D and cordycepin (3'-deoxyadenosine) on androgen receptors in short-term cultures of rat ventral prostate tissue. Actinomycin D increased nuclear and decreased cytoplasmic levels of androgen-receptor complexes. Cordycepin, in contrast, decreased nuclear and increased cytoplasmic levels of androgen-receptor complexes. Cordycepin markedly decreased the amount of cytosolic androgen-receptor complex that could bind to DNA-cellulose whereas actinomycin D had no effect on DNA-cellulose binding activity. Although both actinomycin D and cordycepin are inhibitors of RNA synthesis, the contrasting effects of cordycepin may be due to inhibition of RNA processing or transport by cordycepin. The effects of these two compounds are consistent with a model of steroid receptor recycling in which RNA facilitates removal of receptors from the nuclear acceptor and the steroid receptor remains associated with the RNA during RNA processing and transport.

Pharmacokinetics and tolerance of desciclovir, a prodrug of acyclovir, in healthy human volunteers

Because of the incomplete absorption of acyclovir (ACV) when given orally in humans, efforts have been made to develop a prodrug of ACV that would be better absorbed from the gastrointestinal tract and then converted in vivo to ACV. One such compound, desciclovir (DCV), is converted to acyclovir in vivo by xanthine oxidase. We gave each of 13 healthy volunteers 250 mg (about 3.25 mg/kg of body weight) of DCV orally thrice daily for 10 days, collected serial plasma and urine specimens, and measured DCV and ACV concentrations. The absorption of DCV was at least 75%, and almost two-thirds of the administered oral dose was recovered in the urine as ACV. Peak ACV levels in plasma were about 5 micrograms/ml and were reached in less than 1 h. The levels of ACV achieved in plasma were of the same magnitude as those reported for subjects given intravenous ACV at a dose of 2.5 mg/kg and approximately 10-fold higher than levels attained after administration of 200 mg of oral ACV every 4 h as measured in previous studies. The half-life of DCV was 0.85 +/- 0.16 h, compared with 2.6 +/- 0.5 h for ACV, indicating rapid conversion of DCV to ACV. There was no substantial increase in ACV levels in plasma on day 11 compared with day 2. No serious or consistent adverse effects were noted. In particular, the creatinine level in serum did not significantly rise in any subject and remained within the normal range in all.

Androgen repression of the production of a 29-kilodalton protein and its mRNA in the rat ventral prostate

The regression of the ventral prostate, after a rat is deprived of androgens by castration, is accompanied by a marked decrease in the prostate's ability to synthesize RNA and major proteins. Surprisingly, in vitro translation of prostate RNA, isolated from rats 2 days after castration, detects four proteins with Mr of approximately 29,000, 37,000, 46,000, and 49,000 whose message levels increased 4- to 12-fold compared to results from normal rats. According to cDNA dot hybridization analysis, the increase after castration in the level of the 29-kDa protein-mRNA (per unit amount of DNA) was reversed within 6 h by androgen treatment of castrated rats. In contrast, the level of a mRNA in male rat liver, which hybridized to a cloned probe for the prostate 29-kDa protein-mRNA was reduced by castration and increased by androgen treatment. During an in vitro incubation, the ventral prostates of normal rats were much less efficient than the prostates of rats castrated 2 days earlier in synthesizing a 29-kDa protein. Despite the fact that androgenic manipulation of rats induced very rapid and significant changes in the production of the 29-kDa protein and in the level of its mRNA, the cellular level of this protein in the prostate, as determined by radioimmunoassay, was maintained at near normal values throughout the 2-week experimental period. Thus, the prostate appears to have a mechanism, based on androgen repression of certain genes, to maintain the cellular levels of the 29-kDa protein and possibly other structurally or functionally important proteins during both the periods of androgen-dependent growth and the castration-induced regression. The loss of such a regulatory mechanism may result in androgen-independent abnormal prostate growth.

Neuroendocrine carcinoma of the skin: an immunohistochemical study of tumor markers and neuroendocrine products

Fifteen neuroendocrine carcinomas of the skin (Merkel cell tumors) were stained within the constraints of tissue availability by the Grimelius method and immunohistochemically for keratin, neuron-specific enolase (NSE), carcinoembryonic antigen (CEA), S-100, common leukocyte antigen (CLA), met-enkephalin, bombesin, calcitonin, ACTH, gastrin, and somatostatin. Focal argyrophilia was present in 5 of 12 tumors. All tumors tested demonstrated immunoreactivity for NSE and 5 tumors were positive for keratin. One tumors appeared to demonstrate focal ACTH-like immunoreactivity, but otherwise no immunoreactivity for the above mentioned polypeptide hormones was noted in 11 completely studied tumors. One tumor contained histologically obvious areas of squamous differentiation in addition to areas of Merkel cell tumor. In various tumors, keratin immunoreactivity was present either in areas of histologically obvious squamous differentiation, in randomly scattered single cells not histologically identifiable as squamous, or in a paranuclear dot-like distribution. Immunoreactivity for CEA, S-100 and CLA was not present in any tumors. The lack of met-enkephalin and the presence of squamous differentiation in these tumors indicates multidirectional differentiation in a fashion not phenotypically typical of Merkel cells.

Autoimmune anti-androgen-receptor antibodies in human serum

Circulating autoantibodies to human and rat androgen receptors are present at high titers in the blood sera of some patients with prostate diseases. The antibodies from some serum samples were associated with a purified IgG fraction and interacted with the 3.8S cytosolic androgen-receptor complexes of rat ventral prostate to form 9- to 12S units. Other serum samples, however, formed 14- to 19S units, suggesting that other immunoglobulins might be involved. In the presence of an anti-human immunoglobulin as a second antibody, the androgen-receptor-antibody complexes could be immunoprecipitated. The antibodies interacted with the nuclear and the cytosolic androgen-receptor complexes, either the DNA-binding or the nonbinding form, but not with receptors for estradiol, progestin, or dexamethasone from a variety of sources. Human testosterone/estradiol-binding globulin, rat epididymal androgen-binding protein, or rat prostate alpha-protein (a nonreceptor steroid-binding protein) also did not interact with the antibodies to form immunoprecipitates. About 37% of male and 3% of female serum samples screened had significant antibody titer. The chance of finding serum with a high titer is much better in males older than 66 years than in the younger males or females at all ages. The presence of the high-titer antibodies may make it possible to prepare monoclonal antibodies to androgen receptors without purification of the receptors for immunization.

Polyamine-stimulated phosphorylation of prostatic spermine-binding protein is mediated only by cyclic AMP-independent protein kinases

Spermine-binding protein (a rat ventral prostatic protein with high affinity for spermine) was phosphorylated in situ through the action of intrinsic cellular protein kinase(s), suggesting it to be a phosphoprotein in vivo. The purified protein served as a substrate in a number of cyclic AMP-independent protein kinase reactions in vitro, but not for cyclic AMP-dependent, Ca2+ + calmodulin-dependent or Ca2+ + phospholipid-dependent protein kinases. Available data indicate that at least one of the cyclic AMP-independent protein kinases (cytosolic protein kinase C2) may be physiologically relevant in mediating the phosphorylation of this protein. The phosphorylation reaction was stimulated several-fold in the presence of spermine. Spermidine was somewhat less effective, whereas putrescine, cadaverine and 1,6-hexanediamine were minimally active. Phospho amino acid analysis of 32P-labelled spermine-binding protein indicated that phosphoserine was the only labelled phospho amino acid. Spermine-binding protein did not undergo autophosphorylation, or modify the stimulative effect of spermine on the phosphorylation of other substrates such as non-histone proteins. In situ the phosphorylation of spermine-binding protein in tissue from castrated rats was markedly diminished as compared with the normal. Since the phosphorylation of spermine-binding protein appears to be mediated by cyclic AMP-independent protein kinase(s) whose activity in the prostate is under androgenic control, it is suggested that androgen-dependent modulation of the protein kinase(s) exerts a regulatory control (via phosphorylation-dephosphorylation) on the spermine-binding activity and stability of this protein in vivo. Further, since this protein is a substrate for only the cyclic AMP-independent protein kinases, it could serve as a tool for the investigation of such kinases.

Steroid metabolism and binding activity in a murine renal tumor cell line

The purpose of this study was to partially characterize the steroid binding activity of murine renal tumor cells in continuous culture. The steroid receptor content of a cloned renal tumor cell line (RAG) and a subline RAG-2 was examined by sucrose gradient analysis, hydroxylapatite and dextran-coated charcoal methods. The RAG cells lacked estrogen- and progestin-binding activity, whereas specific 5 alpha-dihydrotestosterone (DHT) and dexamethasone (Dx) binding activities were detected as 8S peaks on low salt gradients. The specificity of DHT binding was examined by sucrose gradient analysis: DHT, R1881 and ORG2058 all completely inhibited [3H]DHT binding whereas diethylstilbestrol and Dx were ineffective. The androgen receptor content of the RAG cells was approx. 15 fmol/mg cytosol protein by the hydroxylapatite-filter assay, with an estimated Kd for methyltrienolone (R1881) of 5 nM at 0 degrees C. Scatchard analysis of [3H]Dx binding by RAG cytosol showed a Kd of 6 nM for Dx and 44 nM for corticosterone at 0 degrees C. Glucocorticoid receptor levels were estimated to be 182 fmol/mg cytosol protein by dextran-coated charcoal assay. Metabolism of [3H]testosterone and [3H]DHT by RAG cells was examined 1, 4 and 6 h after exposure to labeled hormone. Radioactive DHT was the primary intracellular metabolite recovered after exposure to [3H]testosterone. There was little conversion of DHT to androstanediol.

Analysis of androgen-sensitivity in rat prostate X mouse kidney cell hybrids

Variant androgen-sensitive cell lines were produced by fusing freshly isolated epithelial cells from the rat ventral prostate with a line of murine renal tumor (RAG) cells. The properties of the cloned lines of the prostate X RAG hybrids can be summarized as follows: (1) the modal chromosome number of the hybrid cell lines ranged from 68 to 176; (2) the cells had doubling times of 7.6-49.5 h; and (3) epitheloid, ameboid and intermediate morphologies were observed among the various lines. The proliferative response of various hybrid lines to treatment with 10 nM 5 alpha-dihydrotestosterone was used to classify the hybrids as either very sensitive (greater than 40% reduction in cell doubling time), sensitive (greater than 10% reduction in doubling time) to androgens, or insensitive (less than 10% reduction in doubling time) to androgens. There was no direct relationship between the androgen-sensitivity of the cells and their androgen receptor content, suggesting that these variant cell lines may be useful for the study of the genetic factors involved in cellular responses to androgens.

Immunochemical characterization of the androgen-dependent spermine-binding protein of the rat ventral prostate

A solid-phase radioimmunoassay was developed to measure the level of the androgen-dependent spermine-binding protein (SBP) in the cytosol fraction of the rat ventral prostate during endocrine manipulation. The concentration of SBP and immunologically cross-reacting material (CRM) in the ventral prostate was at least 5000 times higher than the level of CRM detected in rat serum or cytosol from other rat tissues. Cytosol from the ventral prostate of intact rats was separated by DEAE-cellulose chromatography into three major fractions of CRM. One of these fractions corresponded to the elution position of SBP. Cytosol prepared from rats 48 h after castration lacked SBP and one of the two other fractions of CRM. This loss coincided with an increase in CRM in the remaining fraction. No significant difference was detected in the total level of CRM when intact and 48 h-castrated rats were compared. Injection of rats with 5 alpha-dihydrotestosterone (DHT) immediately after castration prevented these changes in the profile of CRM. Several proteins cross-reacting with antibodies to purified SBP were detected in cytosol by using an immunoblot procedure. The highest-Mr band corresponded to SBP. The effect of short- and long-term castration and subsequent DHT treatment on CRM was studied by using the immunoblot technique. Short-term castration (2 days) led to the disappearance of CRM coinciding with SBP (Mr 35 000-38 000) and an increase in smaller forms of CRM (Mr 24 000 and 22 000). Injection of rats with DHT 2 days after castration led to the reappearance of CRM corresponding to SBP, which returned to normal levels within 4 to 5 days of treatment. Long-term castration (up to 14 days) led to a gradual disappearance of all CRM; subsequent DHT treatment led to the reappearance of all forms of CRM and normal levels were attained within 5 days. We have identified SBP and the various forms of CRM as a secretory product of the rat ventral prostate by immunohistochemical staining and by DEAE-cellulose fractionation of prostatic fluid. Prostatic fluid is rich in proteolytic activity and these proteinases may be responsible for processing SBP to small forms of CRM.

The use of a hydroxylapatite-filter steroid receptor assay method in the study of the modulation of androgen receptor interaction

Receptors for androgen, estrogen, and glucocorticoid can be assayed by hydroxylapatite adsorption of the radioactive steroid-receptor complex and washing of the adducts on membrane filters mounted on a multiple filter holder. The method is economical, very rapid and sensitive. This new receptor assay method was used to study the modulation of androgen receptor of rat ventral prostate by metal ions, thiols, and ligand structure. The interaction of androgen with the naked receptor is inhibited by 10 microM ZnCl2, CdSO4, or CuSO4 but this inhibition is competed by androgen and is reversed by DTT. The androgen-receptor complex is less sensitive to divalent metal ions but Zn2+, at 3 mM, appears to alter the conformation of the receptor and promote the release of androgen. Certain phenanthrene derivatives exhibited striking structural specificities in their ability to compete with radioactive androgen for binding to the prostate receptor. The results suggest that the receptor has binding preference toward individual ring structure in the steroid.

The use of radioactive 7 alpha, 17 alpha-dimethyl-19-nortestosterone (mibolerone) in the assay of androgen receptors

Tritiated 7 alpha, 17 alpha-dimethyl-19-nortestosterone (DMNT; mibolerone), a synthetic androgen stable to metabolic conversion in the rat ventral prostate, is an excellent radioactive ligand for the quantitation and characterization of androgen receptors in prostate, liver, and cultured cells. DMNT is more receptor-selective than 17 alpha-methyl-17 beta-hydroxy-estra-4,9,11-trien-3-one (R1881); DMNT interacts with glucocorticoid and progestin receptors much less strongly than R1881. Unlike 5 alpha-dihydrotestosterone, DMNT does not bind tightly to testosterone-estradiol binding globulin of human serum. The hydroxylapatite-filter assay we employed can clearly distinguish between DMNT binding to androgen receptors of rat ventral prostate and interaction of DMNT with androgen binding protein of epididymides. The prostate cytosol (3H)DMNT-receptor complex sediments in two forms (4 and 8 S) in a low salt medium. In 0.4 M KCl, both the prostate cytosol and nuclear (3H)DMNT-receptor complexes migrated as 3-4 S components. The formation of both the cytosol and nuclear DMNT-receptor complexes is inhibited by antiandrogens and 17 beta-estradiol.

Polyamines inhibit phospholipid-sensitive and calmodulin-sensitive Ca2+-dependent protein kinases

Effects of polyamines on various protein kinases were investigated. It was found that both phospholipid-sensitive Ca2+-dependent protein kinase and myosin light-chain kinase (a calmodulin-sensitive species of Ca2+-dependent protein kinase) were inhibited to different degrees by polyamines, with an approximate order of inhibitory potency of spermine = 1, 12-diaminododecane greater than spermidine = 1, 10-diaminodecane much greater than cadaverine = putrescine. Kinetic analysis revealed that spermine inhibited the phospholipid-sensitive enzyme non-competitively with respect to Ca2+ (Ki = 0.84 mM) and phosphatidylserine (Ki = 0.90 mM); it also inhibited myosin light-chain kinase non-competitively with respect to Ca2+ (Ki = 1.82 mM) and calmodulin (Ki = 2.73 mM). 1, 12-Diaminododecane, in comparison, inhibited the phospholipid-sensitive enzyme competitively with respect to Ca2+ (Ki = 0.45 mM) and phosphatidylserine (Ki = 0.50 mM); it also inhibited myosin light-chain kinase competitively with respect to calmodulin (Ki = 0.63 mM) but non-competitively with respect to Ca2+ (Ki = 1.49 mM). Moreover, spermine (0.5 mM) was found to inhibit markedly phosphatidylserine/Ca2+- and calmodulin/Ca2+-stimulated phosphorylation of endogenous proteins in rat brain particulate fraction. All the polyamines tested were practically without effect on cyclic AMP-dependent and cyclic GMP-dependent protein kinases. Polyarginine, like spermine, was found to be a more selective inhibitor of Ca2+-dependent protein kinases, whereas polyglutamate preferentially inhibited the cyclic nucleotide-dependent enzymes. The present results indicated that, in addition to certain lipophilic compounds (such as trifluoperazine, palmitoylcarnitine, adriamycin and naphthalenesulphonamide) and polypeptides with hydrophobic regions (such as melittin and polymyxin B) previously reported, polycationic compounds (exemplified by polyamines) could also inhibit the two classes of Ca2+-dependent protein kinases requiring either phospholipid or calmodulin as a cofactor. Because of the high cellular concentration (up to 10 mM) and the differential effects of polyamines, it is suggested that spermine, and to smaller extents spermidine and putrescine, may be involved in the regulation of certain Ca2+-dependent protein-phosphorylation systems in vivo.

Intracellular inactivation, reactivation and dynamic status of prostate androgen receptors

The dynamic status of the androgen receptor in prostate cells was studied by incubation of rat ventral prostate with radioactive 17beta-hydroxy-5alpha-androstan-3-one (5alpha-dihydrotestosterone) in the presence and absence of respiratory poisons and inhibitors of protein and RNA synthesis and also by isotope chasing of the radioactive androgen-receptor complexes. The androgen receptor in the prostate appears to go through a dynamic process of recycling between the cytoplasm and the nucleus as well as an inactivation process. The radioactive androgen-receptor complex, however, is maintained at a constant level for at least 2h during incubation at 37 degrees C, even in the absence of new protein synthesis, suggesting that early androgen actions may not require a depletion of a major portion of cellular receptor. In the presence of 2,4-dinitrophenol, the androgen receptor is rapidly deactivated (half life, 2min). The inactive receptor can be reactivated efficiently by an energy-dependent process, even in the absence of protein synthesis. Receptor binding of androgen and nuclear chromatin binding of the androgen-receptor complex are fast processes; half-maximum binding can be achieved within 1 and 10min respectively. On the contrary, the overall process of the release of the receptor complex from nuclear chromatin and its reappearance in the cytosol fraction has a long half life of about 70min. This slow process may reflect the involvement of the steroid-receptor complex in a time-consuming mechanism that is essential for hormone responses. Actinomycin D can increase the nuclear receptor level by 50% or more. This increase is not due to a decrease in the rate of receptor release from nuclei or to inhibition of DNA degradation by the antibiotic.

Treatment of herpes virus infections in immunocompromised patients with acyclovir by continuous intravenous infusion

Sixteen immunocompromised patients with herpes virus infections were treated for three to five days with continuously administered intravenous acyclovir. Patients received initial acyclovir infusions over 5 minutes in dosages ranging from 1.5 to 5.0 mg/kg followed by continuously infused acyclovir at 7.2, 14.4, 21.6, 28.8, 36.0, or 43.2 mg/kg per day. The mean serum plateau levels of acyclovir determined by radioimmunoassay ranged from 4.1 microM for the 7.2 mg/kg per day dosage to 36.6 microM for the 43.2 mg/kg per day dose. A mean of 75 percent of acyclovir administered was recovered in the urine of patients treated. Eleven of 13 patients with varicella-zoster virus (VZV) infections had no new vesicle formation after three days of acyclovir treatment and all patients ceased to have new vesicles after five days of therapy. For the nine patients from whom complete viral cultures were available, six ceased to shed virus at three days, and viral shedding ceased by five days in all patients treated with acyclovir. No clinical or laboratory adverse reactions were associated with acyclovir therapy. These data suggest that acyclovir given by continuous intravenous infusion may be useful in the treatment of herpes virus infections in immunocompromised patients.

Prostate alpha-protein. Isolation and characterization of the polypeptide components and cholesterol binding

alpha-Protein, a major glycoprotein in the cytosol fraction of rat ventral prostate, has a molecular weight of about 50,000 and can be dissociated, by sodium dodecyl sulfate, into two different subunits (A and B). alpha-Protein has three different polypeptide components with apparent molecular weights of 10,000 (I), 14,000 (II), and 15,000 (III). These components were purified to homogeneity and their amino acid compositions were determined. Subunit A is composed of Components I and III, whereas subunit B is composed of Components II and III. Carbohydrate was detectable only on Component III. Component III isolated from subunit A and Component III isolated from subunit B appear to be identical. The purified alpha-protein contains 0.7-1 mol of cholesterol/mol of protein. If cholesterol was removed by acetone, about 1 mol of 5 alpha-dihydrotestosterone or pregnenolone could bind to 1 mol of alpha-protein. In the presence of 2 mM ZnCl2, alpha-protein can form dimers and tetramers. In cell-free systems, alpha-protein can inhibit binding of the androgen-receptor complex to nuclear chromatin and also can promote the release of the complex already bound to chromatin. This effect is due to polypeptide Component I.

Prostate alpha-protein. Complete amino acid sequence of the component that inhibits nuclear retention of the androgen-receptor complex

The amino acid sequence of Component I of alpha-protein, a glutamic acid-rich protein, is presented. Component I is a single chain polypeptide which consists of 88 amino acid residues with a molecular weight of 10,191. Component I has the amino acid composition Lys6, His, Arg2, Cys3, Asp5, Asn2, Thr3, Ser4, Glu13, Gln3, Pro3, Gly2, Ala6, Val9, Met4, Ile4, Leu8, Tyr6, Phe3, Trp, with serine and asparagine as NH2(-) and COOH-terminal amino acids, respectively. Automated sequences analysis of the whole protein, as well as characterization of the peptides obtained from trypsin, chymotrypsin, and staphylococcal protease digestion and cyanogen bromide treatment, led to the elucidation of the complete primary structure of this protein.

Androgen-sensitive spermine-binding protein of rat ventral prostate. Purification of the protein and characterization of the hormonal effect

The rat ventral prostate contains a cytosol protein that can non-covalently bind spermine much more tightly than spermidine or other natural diamines. The protein has been purified to homogeneity, as judged by electrophoresis in urea- and sodium dodecyl sulphate-containing polyacrylamide gels. The protein, with or without spermine bound to it, sediments at 3 S in a sucrose gradient with or without 0.4 M-KCl. The molecular weight of the protein is about 30 000. Each molecule of the binding protein can bind one molecule of spermine. In the prostate of rats injected with cycloheximide, the protein appears to have a half-life of about 3.5 h. The spermine-binding activity of an acidic fraction obtained by DEAE-cellulose chromatography of the prostate cytosol proteins is reduced by about 40--60% within 20--40 h after castration. This effect is reversed very rapidly within 15--30 min by intraperitoneal injection of 5 alpha-dihydrotestosterone. The hormonal effect is androgen-specific and is not mimicked by dexamethasone or oestradiol-17 beta. The androgen effect was reduced significantly when rats were injected with cycloheximide or actinomycin D, suggesting that the acidic protein may be one of the earliest proteins induced by androgen in the rat ventral prostate.

Protein factor that inhibits binding and promotes release of androgen-receptor complex from nuclear chromatin

A protein factor that can inhibit binding of the androgen-receptor complex to the nuclear chromatin has been isolated from the cytosol of the ventral prostate of rats. The inhibition is reversible and not caused by an irreversible destruction of the receptor or the chromatin. The inhibitor also can promote, by a temperature-dependent process, the release of steroid-receptor complex already bound to chromatin. It is conceivable that such a protein factor plays a regulatory role in the nuclear-cytoplasmic recycling or chromatin binding of the steroid hormone receptor.

Selective polyamine-binding proteins. Spermine binding by an androgen-sensitive phosphoprotein

Rat ventral prostate contains an acidic protein which can bind spermine selectively. The relative binding affinities of various aliphatic amines for the protein are, in decreasing order, spermine greater than thermine greater than greater than putrecine greater than 1,10-diaminodecane, cadaverine and 1,12-diaminododecane. The binding protein has an isoelectric point at pH 4.3 and a sedimentation coefficient of 3 S. Its molecular weight is approx. 30 000. Histones and nuclear chromatin preparations of the prostate can interact with the binding protein. The spermine-binding activity of the purified prostate protein can be inactivated by treatment with intestinal alkaline phosphatases. The phosphatase treated preparation can then be reactivated by beef heart protein kinase in the presence of cyclic AMP and ATP. The spermine-binding activity of the prostate cytosol protein fraction decreases after castration, but increases very rapidly after the castrated rats are injected with 5alpha-dihydrotestosterone. This finding raises the possibility that, in the postate, certain androgen actions may be dependent on the androgen-induced increase in the acidic protein binding of polyamines and their translocation to a functional cellular site such as nuclear chromatin. In the prostate cytosol, spermine also binds to 4-S tRNAs and to a unique RNA which has a sedimentation coefficient of 1.5 S.

Androgen receptors and the molecular basis for the action of antiadrogens in the ventral prostate

In the rat ventral prostate, various antiandrogens can interfere with the normal formation of an androgen-receptor complex which appears to be required for androgen action. Some of the antagonists may act by inhibiting the enzymatic formation of 5 alpha-dihydrotestosterone or by competing with androgens for the binding sites on the receptors, whereby interacting with and altering the receptor molecules themselves. If the action of an androgen-receptor complex can indeed occur at the stage of gene transcription as well as in certain post-transcriptional processes, the molecular site of antiandrogen action may be in the nuclei and/or cytoplasm of the target cells.

Selective retention and formation of a delta5-androstenediol-receptor complex in cell nuclei of the rat vagina

Cellular protein binding of a number of androstene and androstane derivatives that promote the growth of the vagina in rats has been studied. It was found that cell nuclei of the rat vagina contain a tissue-specific protein that binds 3beta,17beta-dihydroxy-androst-5-ene (delta5-androstenediol), a unique steroid causing growth and keratinization of the vaginal epithelium. The formation of the steroid-protein complex can be demonstrated by the administration of delta5-[3H]androstenediol to ovariectomized rats or by the incubation of minced vagina with the radioactive steroid. The steroid can interact with purified vaginal cell nuclei even in the absence of a cytosol preparation, forming the same steroid-protein complex. The formation of the complex is temperature-dependent; it occurs much more readily at 37 degrees than at 0 degrees. The delta5-[3H]androstenediol-protein complex migrated as about 4 S in a sucrose gradient medium containing 0.4 M KCl. A similar complex can be detected when nuclei of vaginal cells are incubated with 3alpha,17beta-dihydroxy-5alpha-androstane, 3beta,17beta-dihydroxy-5alpha-androstane, and 3beta-hydroxy-androst-5-en-17-one which also have the capability of stimulating vaginal epithelium, although in somewhat different ways. These steroids may bind to different groups of chromatin-bound receptor proteins in various layers of vaginal epithelium. The delta5-androstenediol binding protein is not found in the vaginal cytosol fraction that contains receptor proteins for estrogens and progestins, nor in the cytosol or nuclei of rat uterus cells, but not in muscle, brain, kidney, or liver. Testosterone and 5alpha-dihydrostestosterone bind weakly to the protein, whereas cortisol, androstenedione, 17beta-estradiol, and progesterone do not bind to the same protein by any significant extent.

A very rapid effect of androgen on initiation of protein synthesis in prostate

The initiation of protein synthesis by ribosomal particles of rat ventral prostate was studied by measuring ribosomal binding of an initiator (35-S)methionyl-tRNAf. The binding activity is dependent on ribosomes, GTP, and a prostate cytosol protein fraction. The 40S but not the 60S ribosomal subunit particles are active. The cytosol activity decreases rapidly within one hour after the rat is castrated. This loss is prevented by an intraperitoneal injection of 17beta-hydroxy-5-alpha-androstan-3-one (5-alpha-dihydrotestosterone). The cytosol activity can be stimulated almost immediately (within 10 min) after an intravenous injection of low dose (15 mug per rat) of 5-alpha-dihydrotestosterone into the castrated rat.