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D J Tindall

Publications and source records attributed to D J Tindall.

At least 91 records · Page 5Linked to original sources
PubMed1992

Hormonal regulation of prostate-specific antigen (PSA) glycoprotein in the human prostatic adenocarcinoma cell line, LNCaP.

Prostate-specific antigen (PSA) has emerged as the most useful marker for management of patients with prostate cancer. The regulation of this glycoprotein in vivo has important clinical implications. Indirect evidence indicates that the PSA glycoprotein might be regulated by androgens, and previous studies in this laboratory have demonstrated that PSA mRNA is upregulated by androgens. The current work reports a detailed study of PSA glycoprotein expression as influenced by steroid hormones in a human prostatic adenocarcinoma cell line, LNCaP. First, we have examined the steroid binding specificity of the androgen receptor in this cell line. In comparison with wild-type rat androgen receptor in prostate, the receptor in LNCaP cells has altered affinity for a number of steroids or analogs such as progesterone (R5020), antiprogesterone (RU486), two antiandrogens (cyperoterone acetate and hydroxyflutamide), and an androgen metabolite (epitestosterone). However, its affinity for androgens (mibolerone, dihydrotestosterone, and testosterone) is not changed. The receptor does not bind to the synthetic glucocorticoids (triaminolone acetonide and dexamethasone) nor to a synthetic estrogen DES (diethylstilbestrol). The change of the steroid binding specificity of the receptor is correlated with a single mutation (A----G at nucleotide #876 relative to the initiation codon) of the steroid binding domain of the receptor. The mutation and alteration of steroid-binding specificity of the androgen receptor is also correlated with PSA glycoprotein expression affected by different ligands tested. We have demonstrated that the PSA glycoprotein is upregulated by androgens and is affected by neither epidermal growth factor nor basic fibroblast growth factor. Moreover, PSA glycoprotein could be induced by R5020, estradiol, and epitestosterone; but neither glucocorticoids nor DES had any effect on PSA induction. Interestingly, although the antiandrogen, cyperotone acetate, had the ability to induce PSA, both RU486 and hydroxyflutamide could block androgen and progesterone induction of PSA glycoprotein. Therefore, we conclude that the PSA glycoprotein expression is influenced predominantly by androgens via its receptor, and the mutation of the receptor can affect the expression of this cellular gene by the steroids other than androgens.

Adenocarcinoma↗
PubMed1991

Hormonal regulation of prostate-specific antigen messenger RNA in human prostatic adenocarcinoma cell line LNCaP.

Prostate-specific antigen (PSA) is a member of the kallikrein gene family and is expressed exclusively in human prostatic epithelial cells. PSA protein has been an important biological marker for prostate cancers. Until now, very little was known about the regulation of PSA expression in prostatic cells. In this study, we have developed a specific oligonucleotide probe which recognizes PSA but not the human glandular kallikrein. This is crucial because both PSA and human glandular kallikrein are expressed in the prostate at relatively high levels and have high nucleotide sequence homology (greater than 82%). Utilizing a S-labeled PSA-specific probe, PSA mRNA was localized within the glandular epithelium of the prostate. Northern blot analysis detected a single 1.6-kilobase transcript in LNCaP cells, a cell line derived from a human prostate adenocarcinoma metastasis. Therefore, LNCaP cells were used to study the androgenic effects on PSA mRNA expression. A time course study demonstrated that PSA mRNA was induced by mibolerone (a nonmetabolizable synthetic androgen) and reached maximal levels after 9 h. The induction of PSA mRNA required as little as 0.3 nM mibolerone. In addition to mibolerone, PSA mRNA could be induced by the natural androgen, dihydrotestosterone, but not by the synthetic glucocorticoid, dexamethasone, or the synthetic estrogen, diethylstilbestrol. Moreover, in the presence of dihydrotestosterone, PSA mRNA was depressed by hydroxyflutamide (an antiandrogen). These results suggest strongly that the androgenic effects on PSA mRNA in LNCaP cells may be via the function of the androgen receptor.

Adenocarcinoma↗
PubMed1991

A frame-shift mutation in the androgen receptor gene causes complete androgen insensitivity in the testicular-feminized mouse.

The testicular feminized (Tfm) mouse lacks completely androgen responsiveness; and therefore, is unique for studying the role of androgenic steroids in different biological processes. In order to understand the molecular basis of this mutation, 2.8 kilobases of cDNA encoding the Tfm mouse androgen receptor (AR) were amplified with a polymerase chain reaction (PCR) technique. No large deletion in the coding region of the Tfm mouse AR was detected. However, sequence analysis revealed a single base deletion in the coding region of the Tfm AR mRNA. This mutation, which is located in the amino-terminus domain of the receptor, is predicted to cause a frame-shift in translation resulting in a premature termination of AR synthesis at amino acid 412. In vitro translation studies of the recombinant wild type and Tfm AR's demonstrated that the Tfm AR cDNA failed to produce a full-length receptor. Furthermore, the Tfm AR was demonstrated to lack transcriptional activation capability by cotransfection experiments using the Tfm AR with a reporter plasmid of mouse mammary tumor virus long terminal repeat linked to the chloramphenicol acetyltransferase gene. These studies provide evidence of the molecular defect which causes androgen insensitivity in the Tfm mouse.

Amino Acid Sequence↗
PubMed1991

Prostate-specific antigen and prostatic acid phosphatase: biomolecular and physiologic characteristics.

PSA is a 34-kd 240-amino acid glycoprotein produced by the prostatic epithelial cells. It is a member of the glandular kallikrein gene family and has a high sequence homology with human glandular kallikrein (hGK-1). PSA is a serine protease and has chymotrypsin-, trypsin-, and esterase-like activities. It is secreted into the seminal fluid where it degrades two seminal vesicle proteins that are important components of the semen coagulum, thus playing an important role in semen liquefaction. The production of PSA protein appears to be under the control of circulating androgens acting through the androgen receptor. Therefore, the significance of a low serum PSA value in a patient who has undergone previous antiandrogen therapy may not be the same as that for a patient who has not received endocrine treatment.

Acid Phosphatase↗
PubMed1990

Molecular cloning of androgen receptors from divergent species with a polymerase chain reaction technique: complete cDNA sequence of the mouse androgen receptor and isolation of androgen receptor cDNA probes from dog, guinea pig and clawed frog.

We have cloned and sequenced 2.8 kilobases of cDNA encoding the mouse androgen receptor by RNA amplification with transcript sequencing. Sequence analysis predicts that this cDNA contains an open reading frame of 2697 nucleotides encoding a polypeptide of 899 amino acids. Androgen receptor cDNA probes of dog, guinea pig, and frog were also isolated and sequenced using consensus primers derived from human and rat androgen receptor cDNAs. Northern blot analysis with the species-specific probes revealed similarities in size between amphibian and mammalian mRNAs. These results demonstrate the utility of this technique in obtaining nucleic acid probes and sequence information of steroid receptors from different species. The sequence data and the Northern blot analysis of the receptors in different species demonstrate that the androgen receptor has been well-conserved during evolution.

Amino Acid Sequence↗
PubMed1990

Prostatein C3-mRNA: a sensitive marker of androgen-responsiveness in prostate explant cultures.

Prostatein is an androgen-dependent protein which is secreted by the rat ventral prostate. To determine if prostatein or its mRNA were responsive to androgen in vitro, prostate explants were cultured in media containing 0 or 25 nM dihydrotestosterone (DHT), estradiol (E2), or cortisol (F). Prostatein concentrations in medium were measured by radioimmunoassay at 2 and 4 days and in homogenates at 4 days. They were not changed significantly by any of these steroids. The concentration of the mRNA for the C3-subunit of prostatein was determined by dot hybridization at 0, 2, 4, 6, and 8 days. It was decreased significantly by 2 days when compared with explants cultured in the presence of DHT and significant differences persisted through 8 days. In conclusion, quantitation of the mRNA for the C3-subunit of prostatein in short-term cultures of ventral prostate explants appears to be more sensitive to changes in androgen concentration than does measurement of prostatein, per se. Prostatein C3-mRNA may be a useful marker for in vitro studies of androgen agonists and antagonists.

Androgen-Binding Protein↗
PubMed1990

In situ hybridization of prostate-specific antigen mRNA in human prostate.

Prostate-specific antigen (PSA) mRNA was detected by in situ hybridization utilizing a 428 base pair [35S]-labelled cDNA probe from the 3' noncoding region of the PSA gene. Thirty six fresh surgical specimens were collected from patients undergoing radical retropubic prostatectomy for carcinoma of the prostate. Quantitative analysis of the levels of PSA mRNA in both the benign and malignant tissues was performed using an IBAS 2000 Image Analysis System. The results of this study demonstrated that there is a significant decrease in the expression of PSA mRNA in the carcinoma tissue when compared to the benign epithelium. The average binding (number of silver grains/1 x 10(4) microns. 2) for 20 specimens of malignant epithelium was 475 +/- 161 and 586 +/- 140 for 16 specimens of benign epithelium (p less than 0.05). Eleven patients had both benign and malignant tissue from the same surgical specimen available for study. From these paired specimens, the PSA mRNA expression was also significantly reduced in the malignant epithelium when compared to the benign epithelium, 445 +/- 162 and 588 +/- 135 respectively (p less than 0.005). The PSA protein was detected using a monoclonal antibody to PSA with an immunohistochemical staining technique. The PSA protein expression paralleled the expression of the PSA mRNA in the majority of the tissue sections. Many of the tumor specimens showed a heterogeneous expression of PSA, whereas all of the benign epithelium had a uniform high level of PSA expression. In conclusion, PSA mRNA and protein are located only within the glandular epithelial tissue, the expression of PSA protein parallels that of the PSA mRNA, and both the PSA protein and PSA mRNA are significantly decreased in the malignant epithelium when compared to benign prostatic epithelium.

Adenocarcinoma↗
PubMed1990

Overexpression of a partial human androgen receptor in E. coli: characterization of steroid binding, DNA binding, and immunological properties.

The recent cloning of human androgen receptor (AR) cDNAs in this and other laboratories has provided valuable probes for investigating the structure and function of the AR at the molecular level. We now report the overexpression of a region of the human AR containing both the DNA- and hormone-binding domains in E. coli, which provides a means to produce large amounts of AR for analysis and use in functional studies. Under isopropyl-beta-D-thiogalactopyranoside induction, a tripartite protein, consisting of beta-galactosidase, a collagenase recognition site, and AR polypeptide, was produced in E. coli JM109 using pSS20 a as a vector. About 1 mg of the fused AR could be recovered per liter bacterial culture. The induced protein could readily be detected in a sodium dodecyl sulfate-polyacrylamide gel by Coomassie blue staining. Its identity was confirmed by Western blot analysis using antibodies to both beta-galactosidase and the AR. Scatchard analysis of the androgen-binding activity of the hybrid AR revealed high affinity binding to the synthetic androgen, Mibolerone (Kd, approximately 1.2 nM). Competition studies demonstrated the fusion protein's specificity for androgens. The hybrid receptor formed immune complexes with human anti-AR serum that sedimented at about 19S in 10-50% linear sucrose gradients containing 0.4 M KCl. Gel band shift assays revealed that the hybrid receptor protein forms specific complexes with a synthetic steroid response element derived from the mouse mammary tumor virus long terminal repeat region. These results demonstrate that the recombinant AR expressed in E. coli possesses many of the functional properties characteristic of DNA- and steroid-binding domains of the native AR.

Androgens↗
PubMed1989

The androgen receptor of the testicular-feminized (Tfm) mutant mouse is smaller than the wild-type receptor.

The physicochemical and immunological properties of androgen receptors from kidney and brain of testicular-feminized (Tfm) mutant mice and wild-type mice were compared. Analysis by gel filtration and sucrose density gradients revealed that the mol wt of the mutant receptor was 66K (38A; 3.8S) which was significantly smaller than the 110K (53A; 4.6S) size of the wild-type androgen receptor (P less than 0.05). Mixing experiments failed to demonstrate any role for differential proteolysis in the size differences between these receptors. Interaction of the mutant androgen receptor with specific polyclonal antiandrogen receptor antibodies produced significantly smaller immune complexes than that formed with wild-type receptor (12S vs. 17S; P less than 0.01). This confirmed the smaller size of the Tfm mutant androgen receptor and suggested that it contained fewer epitopes. The Tfm kidney cytosols also demonstrated a decreased concentration of androgen receptor-binding activity relative to that of the wild type. Together, these results suggest that the androgen insensitivity associated with the Tfm phenotype is due to a deficiency of androgen receptor in target tissues and a qualitative defect in the androgen receptor protein itself.

Androgen-Insensitivity Syndrome↗
PubMed1988

Monoclonal antibodies against the androgen receptor: recognition of human and other mammalian androgen receptors.

Monoclonal antibodies against the androgen receptor (AR) will provide useful probes for elucidating both the structure and function of this important regulatory protein. Recently, human autoimmune anti-AR sera have been described. The purpose of the current work was to immortalize lymphocytes from the blood of patients with high titer anti-AR antibodies and to produce monoclonal antibodies against the receptor in vitro. Human serum samples (10 microliters) were incubated in high ionic strength buffer (400 mM KCl) for 16 h at 0 C with [3H]Mibolerone-labeled cytosol (100-200 fmol AR) from Dunning tumors. Receptor-antibody complexes were precipitated with goat antihuman immunoglobulin (Ig) antibody. From our 1005 serum samples examined, 5 specimens were detected which precipitated greater than 40% of the AR. These antibodies recognized the AR from human, rat, mouse, dog, steer, chicken, and hamster, but did not recognize estrogen, progesterone, or glucocorticoid receptors. By sucrose gradient analysis in high salt (0.4 M KCl) 1 of the antisera shifted the 4.4S monomeric receptor to 8S, and the others shifted the receptor to 18S. However, all of the antibodies were shown to be IgG class by immunoprecipitation with class-specific second antibodies. Peripheral blood lymphocytes donated by these patients were isolated by histopaque density gradient sedimentation, activated in vitro, transformed with Epstein-Barr virus, and seeded into 96-well plates. From 263 million human lymphocytes plated in 96-well dishes, 1215 wells gave rise to Epstein-Barr virus-transformed lymphoblastoid cells, and 8 of these wells were determined to be anti-AR positive. Cells from 2 of the positive wells were cloned and designated CB54 and UA67, both of which secreted IgG class antibodies against the AR. These 2 monoclonal antibodies have been shown to be highly specific for the AR and to cross-react with the AR from human, rat, and hamster. Studies with the monomeric form of the AR and its proteolytic fragment using sucrose density gradients have suggested that the 2 antibodies recognize different epitopes on the monomeric AR molecule. Furthermore, by Western blot analysis the antibodies have identified the AR as an 118K protein on a sodium dodecyl sulfate gel, which is consistent with our previous findings of the mol wt of the AR.

Animals↗
PubMed1987

A common molecular weight of the androgen receptor monomer in different target tissues.

Previously reported molecular weights for the monomeric steroid binding subunit of the androgen receptor protein have ranged from 25,000 to 167,000. The molecular weight appeared to vary among different species and target organs, as well as between different investigators. This study has examined androgen receptors from a diverse group of organs and species to determine whether these tissues share a common monomeric form. Gel filtration revealed peaks of specific [3H]dihydrotestosterone binding activity corresponding to Stokes radii of 54, 33, and 20 A in cytosols from several tissues. Phosphocellulose chromatography diminished the appearance of the smaller androgen receptor forms and facilitated the appearance of the larger 54-A form. Mixing experiments suggested that phosphocellulose was stabilizing the 54-A form by binding putative proteases which cleave this larger form. Methods were developed to generate homogenous preparations of a given androgen receptor size for comparative study. Sucrose density gradient analysis showed sedimentation coefficients of 4.5-5.0, 3.5-4.0, and 2.5-3.0 S, respectively. The corresponding calculated molecular weights were 109,000-121,000, 52,000-59,000, and 22,000-27,000. Scatchard analysis of each of these androgen receptor forms demonstrated very similar affinity for [3H]dihydrotestosterone (Kd approximately 1 nM), and each form possessed the ability to bind to DNA-cellulose. Extensively purified preparations of androgen receptor from R3327 tumor contained varying amounts of the three receptor forms even though molybdate and phosphocellulose were used to stabilize the androgen receptor protein during purification.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Responses of NBT-II bladder carcinoma cells to conditioned medium from normal fetal urogenital sinus.

In vitro studies were conducted to determine whether conditioned medium from rat fetal urogenital sinus explants would affect phenotypic characteristics of NBT-II urinary bladder carcinoma cells in culture. NBT-II cells were exposed to medium (30%, v/v) conditioned for 48 h by intact urogenital sinus explants derived from 18-day fetal rats. Upon exposure for 23 h the [3H]thymidine incorporation by NBT-II cells was decreased by 40.3% relative to control cultures. This effect was paralleled by a similar decrease in proliferation. NBT-II cultures decreased in cell number by 32.1 and 45.8% on days 2 and 4, respectively, after exposure to conditioned medium. Although cell proliferation was inhibited, conditioned medium acted to induce an increase in protein secretion. An increase of 18.6% was observed in the incorporation of [35S]methionine into newly synthesized, secreted proteins by NBT-II cells exposed to conditioned medium for 23 h. Morphologically the NBT-II cells exposed to conditioned medium were larger, more spread out, and exhibited a greater array of lamellipodia and filopodia, although [35S]methionine incorporation into cellular proteins was decreased by 11.1%. These results suggest that diffusable factors produced by fetal urogenital sinus explants can induce changes in proliferation, protein synthesis, protein secretion, and phenotypic morphology of NBT-II carcinoma cells in culture.

Animals↗
PubMed1987

Androgenic regulation of luteinizing hormone secretion: relationship to androgen binding in sheep pituitary.

Castrated ram lambs (wethers) were investigated for sensitivity to androgen feedback and to determine whether this feedback inhibition of luteinizing hormone (LH) was associated with changes in pituitary androgen receptors. Administration of Silastic capsules containing either dihydrotestosterone or testosterone was found to produce dose-dependent inhibitory effects on serum LH levels in wethers. Physiological dosages of these androgens (i.e., those that produce serum levels of dihydrotestosterone [0.24 ng/ml] or testosterone [2.1 ng/ml] similar to those of intact rams) resulted in differential inhibition of serum LH and LH content of the anterior pituitary. Whereas the inhibitory effect of dihydrotestosterone on pituitary LH content was much more dramatic than that seen with testosterone, the high dosage of testosterone also produced a substantial decrease in pituitary LH content. Responses of the pituitary to changes in serum androgen were compared to responses of the seminal vesicle, which served as a control androgen target organ. Androgen levels were positively correlated with seminal vesicle weights, but pituitary weights were unaffected by castration and/or androgen replacement. Treatments with dihydrotestosterone were associated with decreased cytosol androgen binding activity (i.e., receptors) in pituitary and seminal vesicle, suggesting that both of these tissues were sites of androgen action. Although testosterone inhibited serum LH levels, pituitary cytosol androgen receptors were not affected by changes in serum testosterone. We conclude from these data that dihydrotestosterone is a physiological regulator of pituitary LH secretion in the ram and that further study is needed to investigate the complex actions of testosterone and its metabolites on pituitary function.

Androgens↗
PubMed1986

Properties of an intermediate-sized androgen receptor: association with RNA.

This study identifies an intermediate-sized androgen receptor and characterizes its relationship with the 9.1S and 4.4S receptor forms. Under low ionic conditions, at 2-4 degrees C, there exists a 9.1S (+/- 0.17) (n = 30) oligomeric form which does not bind to DNA. Under high ionic conditions, this form dissociates to a 4.4S (+/- 0.08) (n = 18) monomeric form. When the salt concentration is lowered, the 4.4S monomer converts to a species with an intermediate sedimentation coefficient of 7.7S (+/- 0.15) (n = 17) which binds to DNA. Unlike the 9.1S oligomer the 7.7S form is not maintained by sodium molybdate under high ionic conditions but rather dissociates to the 4.4S monomer. To determine whether these forms were associated with RNA, the 7.7S form was incubated with RNase A and analyzed by density gradient centrifugation. The 7.7S form was digested fully by RNase to the 4.4S monomer. The 7.7S form demonstrated a buoyant density of 1.2459 +/- 0.014 g/cm3 (n = 6) in metrizamide gradients, suggesting a ribonucleoprotein component. The sedimentation coefficient of the 9.1S form was unaffected by RNase. These data suggest that the intermediate 7.7S receptor form is composed of 4.4S monomer associated with a ribonucleoprotein molecule(s).

Animals↗
PubMed1986

Characterization of steroid receptors in human prostate using mibolerone.

Accurate quantitation of androgen receptors requires a radioactive ligand which has affinity and specificity for the receptor and which is stable to metabolic enzymes. In this report, we have characterized the properties of 7 alpha,17 alpha-dimethyl-17 beta-hydroxy-4-estren-3-one (mibolerone) in human benign hyperplastic prostate cytosol and compared them to those of 17 beta-hydroxy-17 alpha-methyl-estra-4,9,11-trien-3-one (R1881). Mibolerone was found to have an affinity (Kd = 1.5 nM) greater than R1881. (Kd = 2.3 nM) for the androgen receptor in human prostate tissue. Surprisingly, mibolerone was found to bind with high affinity to the progesterone receptor in both human prostate (Kd = 5.9 nM) and rabbit uterus (Kd = 1.1 nM). However, binding to this receptor in both species could be blocked with a 500-fold excess of triamcinolone acetonide. [3H]Mibolerone binding to the androgen receptor was competed effectively with unlabeled dihydrotestosterone, R1881, and mibolerone but not by progesterone, diethylstilbestrol or R5020, in the presence of triamcinolone acetonide. Interestingly, mibolerone was more resistant to metabolism than R1881 in prostate cytosol when exposed to elevated temperatures (30 degrees C) for extended periods of time. However, when exposed to high-intensity ultraviolet irradiation, both compounds lost 50% of their binding ability in about 30 minutes. Mibolerone was found to have a very low affinity (Ki = 540 nM) for human sex steroid binding protein. These studies demonstrate that mibolerone is a useful ligand for androgen receptor assays. They also emphasize the need for including competitors of progesterone receptor binding in assays utilizing this steroid for androgen receptor measurements.

Animals↗
PubMed1986

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.

Adenocarcinoma↗