Abnormal Androgen Receptor Research Articles

In silico comparison between the mutated and wild-type androgen receptors and their influence on the selection of optimum androgenic receptor blockers for the treatment of prostate cancer

Background: Prostate cancer is a disease that occurs in men aged more than 50 years. In Iraq, 8.89 men per 100,000 population suffer from prostate cancer, with the incidence being 14,016 cases and mortality being 6,367 cases. Despite advances in treatment against prostate cancer, it can become resistant to drugs. Therefore, the aim of current study was to search and identify binding sites for the repositioning of drugs by computational methods (docking). Methods: Based on the protein structure of the wild androgen receptor, the analysis parameters (22x22x22 on the X, Y, and Z axes) were established. Results: The interactions of the natural ligands with androgen receptor were 10.0 (testosterone) and 10.8 (dihydrotestosterone) while mutated androgen receptor (T877A) had a low affinity with testosterone and dihydrotestosterone (-5.3 and -6.7, respectively). In the interactions of both receptors with the reported inhibitors (antagonists), a decrease with Bicalutamide (-8.3 and -4.3, respectively) and an increase in affinity with Flutamide and Nilutamide (-7.7 and 8.6, wild AR; -8.7 and -9.3 AR T877A) were observed. As for Enzalutamide and Apalutamide (second-generation antagonists), the change was minimal between wild androgen receptor and T877A (-7.6 and -7.7; -7.3 and -7.3, respectively). The change in the affinity of the ligands with androgen receptor and androgen receptor T877A shows how a mutation alters the bonds between these molecules. Conclusion: The identification of key sites and potent inhibitors against abnormal androgen receptor functions will enrich prostate cancer treatments.

In silico comparison between the mutated and wild-type androgen receptors and their influence on the selection of optimum androgenic receptor blockers for the treatment of prostate cancer

Background: Prostate cancer is a disease that occurs in men aged more than 50 years. In Iraq, 8.89 men per 100,000 population suffer from prostate cancer, with the incidence being 14,016 cases and mortality being 6,367 cases. Despite advances in treatment against prostate cancer, it can become resistant to drugs. Therefore, the aim of the current study was to search and identify binding sites for the repositioning of drugs by computational methods (docking). Methods: Based on the protein structure of the wild androgen receptor, the analysis parameters (22x22x22 on the X, Y, and Z axes) were established. Results: The interactions of the natural ligands with androgen receptor were 10.0 (testosterone) and 10.8 (dihydrotestosterone) while mutated androgen receptor (T877A) had a low affinity with testosterone and dihydrotestosterone (-5.3 and -6.7, respectively). In the interactions of both receptors with the reported inhibitors (antagonists), a decrease with Bicalutamide (-8.3 and -4.3, respectively) and an increase in affinity with Flutamide and Nilutamide (-7.7 and 8.6, wild AR; -8.7 and -9.3 AR T877A) were observed. As for Enzalutamide and Apalutamide (second-generation antagonists), the change was minimal between wild androgen receptor and T877A (-7.6 and -7.7; -7.3 and -7.3, respectively). The change in the affinity of the ligands with the androgen receptor and androgen receptor T877A shows how a mutation alters the bonds between these molecules. Conclusion: The identification of key sites and potent inhibitors against abnormal androgen receptor functions will enrich prostate cancer treatments.

In silico comparison between the mutated and wild-type androgen receptors and their influence on the selection of optimum androgenic receptor blockers for the treatment of prostate cancer.

Background: Prostate cancer is a disease that occurs in men aged more than 50 years. In Iraq, 8.89 men per 100,000 population suffer from prostate cancer, with the incidence being 14,016 cases and mortality being 6,367 cases. Despite advances in treatment against prostate cancer, it can become resistant to drugs. Therefore, the aim of current study was to search and identify binding sites for the repositioning of drugs by computational methods (docking). Methods: Based on the protein structure of the wild androgen receptor, the analysis parameters (22x22x22 on the X, Y, and Z axes) were established. Results: The interactions of the natural ligands with androgen receptor were 10.0 (testosterone) and 10.8 (dihydrotestosterone) while mutated androgen receptor (T877A) had a low affinity with testosterone and dihydrotestosterone (-5.3 and -6.7, respectively). In the interactions of both receptors with the reported inhibitors (antagonists), a decrease with Bicalutamide (-8.3 and -4.3, respectively) and an increase in affinity with Flutamide and Nilutamide (-7.7 and 8.6, wild AR; -8.7 and -9.3 AR T877A) were observed. As for Enzalutamide and Apalutamide (second-generation antagonists), the change was minimal between wild androgen receptor and T877A (-7.6 and -7.7; -7.3 and -7.3, respectively). The change in the affinity of the ligands with androgen receptor and androgen receptor T877A shows how a mutation alters the bonds between these molecules. Conclusion: The identification of key sites and potent inhibitors against abnormal androgen receptor functions will enrich prostate cancer treatments.

Clinical characteristics, AR gene variants, and functional domains in 64 patients with androgen insensitivity syndrome

BackgroundAndrogen insensitivity syndrome (AIS) is caused by abnormal androgen receptor (AR) genes that show variable genotypes and phenotypes. However, the correlation between genotype and phenotype is unclear.MethodsWe retrospectively evaluated 64 patients with AIS at Shanghai Children's Hospital from 2015 to 2022. We analysed the clinical data of the patients, including hormone levels, AR gene variants, and functional domains.ResultsVariants occurred in the 3 major functional domains in 56 patients, including 23 patients with complete androgen insensitivity syndrome (CAIS) and 33 with partial androgen insensitivity syndrome (PAIS). The incidence of nonscrotal fusion (P = 0.019) and proximal urethral opening (P = 0.0002) in the ligand-binding domain (LBD) group was higher than that in the non-LBD group. The phallus length in the LBD group was significantly shorter than that in the non-LBD group (P = 0.009). The external masculinization score (EMS) in the LBD group was significantly lower than that in the non-LBD group (P = 0.013). The levels of inhibin-B (INHB; P = 0.0007), basal luteinizing hormone (LH; P = 0.033), LH peak (P = 0.002), and testosterone (T) after human chorionic gonadotropin (HCG) stimulation (P = 0.001) in the LBD group were higher than those in the non-LBD group. There were 53 variants in 64 patients, including 42 reported and 11 novel AR variants, including p.Met247Arg, p.Asp266Glyfs*39, p.Arg362Serfs*140, p.Ala385Val, p.Glu541Asp, p.Pro613Leu, p.Pro695Leu, p.Asn757Asp, c.1616 + 1dup, c.1886-1G > A and exon 5–7 deletion.ConclusionsThe EMS of patients with AIS in the LBD group was significantly lower than that in the non-LBD group. The phallus length was shorter, and the incidences of proximal urethral opening and nonscrotal fusion were higher, suggesting that the phenotypes in the LBD group were more severe. The levels of INHB, basal LH, peak LH, and T after HCG stimulation in the LBD group were higher than those in the non-LBD group, suggesting that androgen resistance in the LBD group was more severe. We identified 53 variants in 64 patients: 42 reported and 11 novel AR variants. These findings provide new and deeper insight into AIS diagnosis and genetic assessment of AIS.

In silico comparison between the mutated and wild type androgen receptors and their influence on the selection of optimum androgenic receptor blocker for treatment of prostate cancer

Background: Prostate cancer is a disease that occurs in men aged more than 50 years. In Iraq, 8.89 men per 100,000 population suffer from prostate cancer, with the incidence being 14,016 cases and mortality being 6,367 cases. Despite advances in treatment against prostate cancer, it can become resistant to drugs. Therefore, the aim of current study was to search and identify binding sites for the repositioning of drugs by computational methods (docking). Methods: Based on the protein structure of the wild androgen receptor, the analysis parameters (22x22x22 on the X, Y, and Z axes) were established. Results: The interactions of the natural ligands with androgen receptor were 10.0 (testosterone) and 10.8 (dihydrotestosterone) while mutated androgen receptor (T877A) had a low affinity with testosterone and dihydrotestosterone (-5.3 and -6.7, respectively). In the interactions of both receptors with the reported inhibitors (antagonists), a decrease with Bicalutamide (-8.3 and -4.3, respectively) and an increase in affinity with Flutamide and Nilutamide (-7.7 and 8.6, wild AR; -8.7 and -9.3 AR T877A) were observed. As for Enzalutamide and Apalutamide (second-generation antagonists), the change was minimal between wild androgen receptor and T877A (-7.6 and -7.7; -7.3 and -7.3, respectively). The change in the affinity of the ligands with androgen receptor and androgen receptor T877A shows how a mutation alters the bonds between these molecules. Conclusion: The identification of key sites and potent inhibitors against abnormal androgen receptor functions will enrich prostate cancer treatments.

The role of JMJD6/U2AF65/AR-V7 axis in castration-resistant prostate cancer progression

Castration-resistant prostate cancer (CRPC) remains prostate cancer research and treatment bottleneck. Abnormal androgen receptor (AR) activation still has a pivotal role in CRPC. Multiple mechanisms involve the process, of which overabundant AR-V7 mRNA splicing production is currently focused and increasingly studied. However, factually, there is no definite conclusion about regulation of AR-V7 mRNA splicing. Recently developed knowledge has demonstrated that JMJD6 and U2AF65 as a hopeful approach in mRNA splicing regulation. The authors propose a novel possible mechanism elucidating AR mRNA splicing for CRPC progression using dual-function enzyme JMJD6 and its induced JMJD6/U2AF65/AR-V7 axis. In this hypothesis JMJD6 introduces to AR promoter to demethylate H3R or H4R and promotes AR mRNA transcription via its demethylase activity and interaction with U2AF65. It is expected that JMJD6 could further effectively perform U2AF65 hydroxylation to achieve AR-V7 mRNA splicing via its hydroxylase activity.

Prostate cancer androgen receptor splice variant 7 biomarker study - a multicentre randomised feasibility trial of biomarker-guided personalised treatment in patients with advanced prostate cancer (the VARIANT trial) study protocol

IntroductionProstate cancer is the most common male cancer with one in four developing non-curable metastatic disease. Initial treatment responses to hormonal therapies are transient and further management options lie between...

Heat shock factor-1 influences pathological lesion distribution of polyglutamine-induced neurodegeneration

A crucial feature of adult-onset neurodegenerative diseases is accumulation of abnormal protein in specific brain regions, although the mechanism underlying this pathological selectivity remains unclear. Heat shock factor-1 is a transcriptional regulator of heat shock proteins, molecular chaperones that abrogate neurodegeneration by refolding and solubilizing pathogenic proteins. Here we show that heat shock factor-1 expression levels are associated with the accumulation of pathogenic androgen receptor in spinal and bulbar muscular atrophy, a polyglutamine-induced neurodegenerative disease. In heterozygous heat shock factor-1-knockout spinal and bulbar muscular atrophy mice, abnormal androgen receptor accumulates in the cerebral visual cortex, liver and pituitary, which are not affected in their genetically unmodified counterparts. The depletion of heat shock factor-1 also expands the distribution of pathogenic androgen receptor accumulation in other neuronal regions. Furthermore, lentiviral-mediated delivery of heat shock factor-1 into the brain of spinal and bulbar muscular atrophy mice topically suppresses the pathogenic androgen receptor accumulation and neuronal atrophy. These results suggest that heat shock factor-1 influences the pathological lesion selectivity in spinal and bulbar muscular atrophy.

Abstract A76: MDV3100, a novel androgen receptor signaling inhibitor, promotes cell apoptosis and tumor regression in both in vitro and in vivo models of castration-resistant prostate cancer.

Abstract Prostate tumors initially respond to androgen deprivation therapy but eventually progress despite low serum levels of testosterone. In this stage, known as castration-resistant prostate cancer (CRPC), abnormal androgen receptor (AR) signaling persists and classic anti-androgens such as bicalutamide are ineffective at controlling tumor growth. The novel AR signaling inhibitor MDV3100 has been demonstrated to inhibit AR signaling in preclinical models of CRPC. Here, we investigate further the cellular effects of MDV3100 treatment on AR signaling in in vitro models and in vivo xenograft models of CRPC. Our experiments reveal that MDV3100 (> 100 nM) inhibits dihydrotestosterone (DHT) induced AR-target gene expression in LNCaP cells and LNCaP/AR cells, a CRPC cell culture model in which AR is over-expressed. Inhibition of Prostate-Specific Antigen mRNA expression by MDV3100 was effective at concentrations 10-fold lower than with bicalutamide. As evidenced in other studies and in contrast to bicalutamide, MDV3100 did not display agonistic effects on AR signaling at 10 μM. In contrast to bicalutamide, MDV3100 (> 1 μM) inhibited androgen dependent nuclear translocation of AR, as measured with a quantitative optical based enzyme fragment complementation assay and AR-YFP localization in HEK-293 cells. Furthermore, in the presence of DHT, MDV3100 effectively reduced cell viability of LNCaP cells at concentrations as low as 0.1 μM, 10-fold lower than bicalutamide. MDV3100 also decreased cell viability of LNCaP/AR and W741C-LNcaP cells. We found that the apoptosis marker cleaved-caspase 3 was induced in LNCaP/AR cells treated with 1 M MDV3100 for 48 hours. Under these conditions, MDV3100 was more potent than bicalutamide in decreasing cell viability. Finally, we show that MDV3100 inhibited tumor growth and induced regression of tumor volume in a xenograft model of CRPC generated with LNCaP/AR cells. These results demonstrate that MDV3100, unlike anti-androgens, is effective in both in vitro and in vivo models of CRPC and that its mechanistic advantages over other anti-androgens could be explained by its ability to inhibit AR nuclear translocation and induce cell death. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A76.

Genotyping of Tunisian azoospermic men with Sertoli cell-only and maturation arrest.

Azoospermia factor (AZF) deletions were associated with severe oligospermia and azoospermia with testicular histologies varying from maturation arrest (MA) to Sertoli cell-only (SCO) phenotypes. Abnormal androgen receptor (AR) structure or function has also been implicated in male infertility. To assess the contribution of these genetic defects to azoospermic patients, 19 Tunisian men with SCO (n = 13) or MA (n = 6) were enrolled in this study. Using immunohistochemistry method, we evaluated the expression of AR in testicular biopsy for the two phenotypes. PCR with primers flanking the AR-(CAG)n region and direct sequencing were used to determine AR-(CAG)n length. And PCR amplification of 14 sequence-tagged sites (STSs) located at Yq was used to determine the rate and extent of Y microdeletions. We found a significant difference of the AR expression between SCO and MA cases. Hence, this expression in the testis depends on the status of spermatogenesis. However, we did not find any relationship between the (CAG) repeat and the testicular histology (neither for SCO nor MA). On the other hand, we found a high frequency of AZF deletions (46.2%) in SCOS and in MA (50%). The present results also suggest the contribution of Y chromosome microdeletions in SCO and MA pathogenesis.

Genotyping of Israeli infertile men with idiopathic oligozoospermia.

Microdeletions of the long arm of the Y chromosome involving the azoospermia factor (AZF) region are associated with severe oligo- or azoospermia. Abnormal androgen receptor (AR) structure or function has also been implicated in male infertility. To assess the contribution of these genetic defects to male infertility, 61 Israeli men with severe oligo- (n = 15) or azoospermia (n = 46), were screened for Y chromosome microdeletions, and the AR-(CAG)n repeat length. Fifty fertile Israeli men were similarly analyzed. PCR amplification of 20-54 simple tag sequences (STSs) located at Yq was used to determine the rate and extent of Y chromosome microdeletions. PCR with primers flanking the AR-(CAG)n region and subsequent size fractionation on gradient acrylamide gels were used to determine AR-(CAG)n length. Five azoospermic individuals (5/61-8.2% and 5/46-10.8% of azoospermic patients) displayed Y chromosome microdeletions. The mean CAG repeat number in infertile men was 18.6 +/- 3.0 compared with 16.6 + 2.7 in fertile men (n = 50), a statistically significant difference (p = 0.003). Y chromosome microdeletions contribute to male infertility in our azoospermic population, and the mean length of the AR-CAG is significantly longer in our infertile population than in fertile men.

Molecular basis of androgen insensitivity

Androgens are important steroid hormones for expression of the male phenotype. They have characteristic roles during male sexual differentiation, during development and maintenance of secondary male characteristics, and during the initiation and maintenance of spermatogenesis. The two most important androgens in this respect are testosterone and 5α-dihydrotestosterone. Each androgen has its own specific role during male sexual differentiation, testosterone is involved in the development and differentiation of Wolffian duct derived structures, whereas 5α-dihydrotestosterone, a metabolite of testosterone, is the active ligand in the urogenital sinus and tubercle and their derived structures. The actions of androgens are mediated by the androgen receptor. This ligand dependent transcription factor belongs to the superfamily of nuclear receptors, including those for the other steroid hormones. The androgen receptor gene is located on the X-chromosome at Xq11–12 and codes for a protein with a molecular mass of approximately 110 kDa. Only one androgen receptor cDNA has been identified sofar, despite two different ligands. It is generally accepted that defects in the androgen receptor gene prevent the normal development of both internal and external male structures in 46, XY individuals. The end-organ resistance to androgens has been designated as androgen insensitivity syndrome (AIS) and is distinct from other forms of male pseudohermaphroditism like 17β-hydroxy-steroid dehydrogenase type 3 deficiency, leydig cell hypoplasia due to inactivating LH receptor mutations or 5α-reductase type 2 deficiency. Furthermore, two additional pathological situations are associated with abnormal androgen receptor structure and function — spinal and bulbar muscular atrophy (SBMA, or Kennedy's disease) and prostate cancer. In the AR gene, four different types of mutations have been detected in DNA from individuals with AIS — (i) single point mutations resulting in amino acid substitutions or premature stopcodons; (ii) nucleotide insertions or deletions most often leading to a frame shift and premature termination; (iii) complete or partial gene deletions; and (iv) intronic mutations in either splice donor or acceptor sites, which affect the splicing of AR RNA. The main phenotypic characteristics of individuals with the complete androgen insensitivity syndrome (CAIS) are, female external genitalia, a short, blind ending vagina, the absence of Wolffian duct derived structures, the absence of a prostate, development of gynecomastia and the absence of pubic and axillary hair. Usuallly testosterone levels are elevated at the time of puberty, while also elevated LH levels are found. In the partial androgen insensitivity syndrome (PAIS) several different phenotypes are evident, ranging from individuals with predominantly a female appearance to persons with ambiguous genitalia, or individuals with a predominantly male phenotype. At puberty, elevated LH, testosterone and estradiol levels are observed. Individuals with mild symptoms of undervirilization (mild androgen insensitivity syndrome (MAIS)) and infertility have been described as well. Phenotypic variation between individuals in different families has been described for several mutations. However, in cases of CAIS no phenotypic variation has been described within one single family, in contrast to families with individuals with PAIS. In general AIS, can be routinely analyzed and more than 150 different mutations have been reported now. Differential diagnosis of AIS is possible with syndromes presenting with almost similar phenotypes but with a completely different molecular cause.

Androgen receptor mutations.

Male sexual differentiation and development proceed under direct control of androgens. Androgen action is mediated by the intracellular androgen receptor, which belongs to the superfamily of ligand-dependent transcription factors. At least three pathological situations are associated with abnormal androgen receptor structure and function: androgen insensitivity syndrome (AIS), spinal and bulbar muscular atrophy (SBMA) and prostate cancer. In the X-linked androgen insensitivity syndrome, defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. Complete or gross deletions of the androgen receptor gene have not been found frequently in persons with complete androgen insensitivity syndrome. Point mutations at several different sites in exons 2-8 encoding the DNA- and androgen-binding domain, have been reported for partial and complete forms of androgen insensitivity. A relatively high number of mutations were reported in two different clusters in exon 5 and in exon 7. The number of mutations in exon 1 is extremely low and no mutations have been reported in the hinge region, located between the DNA-binding domain and the ligand-binding domain and which is encoded by the first half of exon 4. Androgen receptor gene mutations in prostate cancer are very rare and are reported only in exons 4-8. The X-linked spinal and bulbar muscle atrophy (SBMA; Kennedy's disease) is associated with an expanded length (> 40 residues) of one of the polyglutamine stretches in the N-terminal domain of the androgen receptor.

Abnormal androgen receptor binding affinity in subjects with Kennedy's disease (spinal and bulbar muscular atrophy).

We have investigated androgen-binding properties of the androgen receptor (AR) in cultured suprapubic skin fibroblasts from six subjects with Kennedy's disease (X-linked spinal and bulbar muscular atrophy). Binding of the synthetic androgen methyltrienolone (R1881) was measured in a monolayer assay, and Scatchard analysis was performed to determine the total number of binding sites and the apparent binding affinity (Kd) of the AR for androgen. Five of the six subjects investigated had an abnormal apparent binding affinity, with Kd values ranging from 0.34-11.7 nmol/L, more than 2 SD from the mean of the normal range (0.19 +/- 0.06 nmol/L). In this group of six patients, there was a significant correlation between the AR Kd and the severity of testicular atrophy and gynecomastia. The number of CAG repeats in the expanded region of exon A of the AR gene was determined in all subjects from whom suprapubic skin fibroblasts were cultured and an additional 12 subjects with Kennedy's disease. In the total group of 18 subjects investigated, there was a trend for an increasing number of CAG repeats associated with decreasing age at onset of different symptoms; however, this correlation was not statistically significant. Thus, we report for the first time a quantitative abnormality of the AR apparent binding affinity in subjects with Kennedy's disease, which appears to be related to the severity of the symptoms of androgen insensitivity.

Abnormal androgen receptor binding affinity in subjects with Kennedy's disease (spinal and bulbar muscular atrophy)

Abnormal androgen receptor binding affinity in subjects with Kennedy's disease (spinal and bulbar muscular atrophy)

X-linked spinomuscular atrophy: a kindred with associated abnormal androgen receptor binding.

We studied androgen receptor function in cultured scrotal skin fibroblasts from eight subjects with X-linked spinal and bulbar muscular atrophy (SBMA) (Kennedy's syndrome) from four families. The neuromuscular and endocrine features were similar in all patients. High-affinity dihydrotestosterone binding (Bmax) was decreased in three patients from one family (average, 11.1 fmol/mg) similar to values in subjects with androgen resistance syndromes. Bmax was normal in five SBMA patients from three other families (average, 26.0 fmol/mg). This finding provides direct evidence for abnormal androgen receptor function in some patients with SBMA. There was some correlation between severity of neuromuscular and endocrine dysfunction, providing further evidence that the two types of manifestations are related.

The androgen receptor in LNCaP cells contains a mutation in the ligand binding domain which affects steroid binding characteristics and response to antiandrogens

The human prostate tumor cell line LNCaP containd an abnormal androgen receptor system with broad steroid binding specificity. Progestagens, estradiol and several antiandrogens compete with androgens for binding to the androgen receptor in the cells to a higher extent than in other androgen sensitive systems. Optimal growth of LNCaP cells is observed after addition of the synthetic androgen R1881 (0.1 nM). In addition, estrogens, progestagens and several antiandrogens do not inhibit androgen responsive growth, but have striking growth stimulatory effects and increase EGF receptor level and acid phosphatase secretion. We have found that the androgen receptor in the LNCaP cells contains a single point mutation changing the sense of codon 868 (Thr to Ala) in the ligand binding domain. Expression vectors containing the normal or mutated androgen receptor sequence were transfected into COS or HeLa cells. Androgens, progestagens, estrogens and several antiandrogens bind the mutated androgen receptor proteon and activate the expression of an androgen-regulated reporter gene (GRE-tk-CAT), indicating that the mutation directly affects both binding specificity and the induction of gene expression. Interestingly, the antiandrogen casodex showed antiandrogenic properties in growth studies of LNCaP cells and did not induced reporter gene activity in Hela cells transfected with the mutant receptor. The mutated androgen receptor of LNCaP cells is therefore a useful tool in the elucidation of different levels of action of steroids and antisteroids.

A mutation in the ligand binding domain of the androgen receptor of human INCaP cells affects steroid binding characteristics and response to anti-androgens

LNCaP prostate tumor cells contain an abnormal androgen receptor system. Progestagens, estradiol and anti-androgens can compete with androgens for binding to the androgen receptor and can stimulate both cell growth and excretion of prostate specific acid phosphatase. We have discovered in the LNCaP androgen receptor a single point mutation changing the sense of codon 868 (Thr to Ala) in the ligand binding domain. Expression vectors containing the normal or mutated androgen receptor sequence were transfected into COS or Hela cells. Androgens, progestagens, estrogens and anti-androgens bind the mutated androgen receptor protein and activate the expression of an androgen-regulated reporter gene construct (GRE-tk-CAT). The mutation therefore influences both binding and the induction of gene expression by different steroids and antisteroids.

Qualitative receptor defects in families with androgen resistance: failure of stabilization of the fibroblast cytosol androgen receptor.

We describe a new method for detecting the presence of a qualitatively abnormal androgen receptor in skin fibroblasts cultured from patients with androgen resistance. Preparation of normal fibroblast cytosol in the presence of sodium molybdate results in stabilization of a 7–8S dihydrotestosterone-receptor complex on sucrose density gradients. Patients with testicular feminization previously identified as having a qualitatively abnormal androgen receptor, as determined by thermolability of monolayer binding, were shown to have failure of stabilization of the cytosol receptor by molybdate. In light of this, we designed a study to see whether this technique might identify previously unrecognized instances of a qualitatively abnormal androgen receptor. Comparison of the thermolability of monolayer binding and molybdate stabilization of cytosol receptor was thus undertaken in 35 families with androgen resistance due to putative disorders of the androgen receptor. The patients included individuals from 15 fami...

390 HORMONAL-METAL ION INTERACTION IN TESTICULAR FEMINIZATION

Testicular feminization syndrome, an X-linked recessive disorder in humans, is caused by the insensitivity of target organs such as testes to the stimulation of androgens. Two animal models are available, the tfm mouse and the tfm rat. In tfm rats abnormal androgen receptor binding and/or defective processing of testosterone occurs. Zinc has been reported to affect dihydrotestosterone-receptor binding in vitro. Our study reports an abnormal testicular zinc level in tfm rats. Copper and zinc concentrations in liver, kidney, adrenals, testes and plasma from tfm and control pairs were determined. Metal contents of the various tissues and plasma of tfm and normal control rats were comparable except testicular zinc which is lower in tfm testes. Testicular zinc content is primarily under the influence of luteinizing hormone (LH) whose concentration is higher in tfm rats. The present results support the proposed metal carrier role of steroid-receptor complex and suggest the LH effect on zinc metabolism may be mediated through this complex. These data also suggest that the action of zinc and androgens on normal testicular development is interrelated.