Androgen receptor polymorphisms and testicular cancer risk

Testicular cancer (TC) is currently the most common malignant solid tumour in Caucasian males aged 15-39 years. Epidemiological evidence suggests that its onset may be due to an imbalance in the action of steroidal sex hormones and their receptors. A faulty androgen receptor signalling pathway can, in fact, cause various male reproductive disorders. The androgen receptor (AR) gene has two polymorphic segments consisting of CAG and GGC repeats. The length of CAG repeats has been shown to affect the regulation of AR activity. In our study, we used fragment analysis to evaluate the AR gene repeats of 302 TC patients and 322 controls, to establish if there is any association between repeat number and TC. This study of the largest Italian caseload investigated to date highlighted three particularly significant aspects. First, a CAG repeat number of ≥25 may be considered a risk factor for the onset of TC, given its greater frequency in patients in comparison with controls. This difference became significant for the non-seminoma group. Second, men with CAG repeats below 21 or above 24 were found to have a, respectively, 50 and 76% higher risk of TC than those with CAG 21-24, suggesting that these too can be considered a risk factor for TC. Finally, stage II patients were more likely to have a CAG repeat number 24 than stage I patients. © 2014 American Society of Andrology and European Academy of Andrology

No association of androgen receptor GGN repeat length polymorphism with infertility in Indian men

Androgens, acting through the androgen receptor (AR), play a role in secondary sexual differentiation from the prenatal stage to adulthood, including spermatogenesis. The AR gene has 2 polymorphic trinucleotide repeats (CAG and GGN) in exon 1. The CAG repeat length polymorphism has been well studied in a variety of medical conditions, including male infertility. Many of these studies have shown an association of the expanded CAG repeats with male infertility, although this is not true for all populations. The GGN repeat, in contrast, has been less thoroughly studied. Thus far, only 4 reports worldwide have analyzed the GGN repeat, alone or in combination with the CAG repeat, in male infertility cases. No such study has been undertaken on infertile Indian men. Therefore, we have analyzed AR-GGN repeats in a total of 595 Indian males, including 277 azoospemric, 97 oligozoospermic, and 21 oligoteratozoospermic cases, along with 200 normozoospermic controls. The analysis revealed no difference in the mean number or the range of the repeat between cases (mean=21.51 repeats, range 15-26 repeats) and controls (mean 21.58 repeats, range 15-26 repeats). Furthermore, no difference was observed when azoospermic (mean=21.53 repeats, range 15-26 repeats), oligozoospermic (mean=21.46 repeats, range 15-26 repeats), and oligoteratozoospermic cases (mean=21.48, range 19-26 repeats) were compared individually with the controls

Expression of mRNA Mastermind-like Domain-containing 1, Androgen Receptor, and Estrogen Receptor in Patients with Hypospadias

BACKGROUND: Androgen (AR) and Estrogen (ER) hormones play an important role in the prenatal and postnatal development of the urogenital tract and especially the penis. Growth factors also influence the development of genital structures. Little is known about the exact role of Mastermind Like Domain 1 (MAMLD1) in sexual development. A role in sex differentiation through supporting testosterone production in critical periods of male development has been suggested. MAMLD1 mutations result in hypospadias with and without a disorder of sexual development (DSD) primarily because of compromised testosterone production around the critical period for fetal sex development, but the underlying etiology remains unclear. AIM: The objective of this study was to investigate the correlation between gene factor MAMLD1, AR, ER1, and ER2 with the incidence of hypospadias. OBJECTIVE: The objective of this study was to investigate the correlation between gene factor MAMLD1, AR, ER1, and ER2 with the incidence of hypospadias. METHODS: From 2017-2018, peri-urethral dartos were harvested from 46 patients with proximal hypospadias, 24 patients with distal hypospadias and 10 patients with normal penile were used as controls. The expressions of MAMLD1, AR, ER1, and ER2 were investigated by one-step quantitative polymerase chain reaction. RESULTS: Median age was 5 years old in the 70 patients with hypospadias and 6 years old in the control subjects. Total specimens taken included 24 distal penile, 46 proximal penile, and 10 normal penile specimens. We found decreasing MAMLD1 and AR expressions, but ER2 expression increased in patients with hypospadias compared to controls, which was statistically significant (p < 0.001). A positive correlation between MAMLD1 and AR was found in patients with hypospadias (r = 0.062; p = 0.038). CONCLUSIONS: Decreasing of MAMLD1 and AR expression was followed by increasing ER2 expression in patients with hypospadias. MAMLD1 had a positive correlation with AR so the defect of MAMLD1 may influence AR and increase the incidence of hypospadias

ZMIZ1 Preferably Enhances the Transcriptional Activity of Androgen Receptor with Short Polyglutamine Tract

The androgen receptor (AR) is a ligand-induced transcription factor and contains the polyglutamine (polyQ) tracts within its N-terminal transactivation domain. The length of polyQ tracts has been suggested to alter AR transcriptional activity in prostate cancer along with other endocrine and neurologic disorders. Here, we assessed the role of ZMIZ1, an AR co-activator, in regulating the activity of the AR with different lengths of polyQ tracts as ARQ9, ARQ24, and ARQ35 in prostate cancer cells. ZMIZ1, but not ZMIZ2 or ARA70, preferably augments ARQ9 induced androgen-dependent transcription on three different androgen-inducible promoter/reporter vectors. A strong protein-protein interaction between ZMIZ1 and ARQ9 proteins was shown by immunoprecipitation assays. In the presence of ZMIZ1, the N and C-terminal interaction of the ARQ9 was more pronounced than ARQ24 and ARQ35. Both Brg1 and BAF57, the components of SWI/SNF complexes, were shown to be involved in the enhancement of ZMIZ1 on AR activity. Using the chromatin immunoprecipitation assays (ChIP), we further demonstrated a strong recruitment of ZMIZ1 by ARQ9 on the promoter of the prostate specific antigen (PSA) gene. These results demonstrate a novel regulatory role of ZMIZ1 in modulating the polyQ tract length of AR in prostate cancer cells

Androgen Receptor Gene CAG Repeat Polymorphism Regulates the Metabolic Effects of Testosterone Replacement Therapy in Male Postsurgical Hypogonadotropic Hypogonadism

Aim. To evaluate the independent role of androgen receptor (AR) gene CAG repeat polymorphism on metabolic effects of testosterone replacement therapy (TRT) in male postsurgical hypogonadotropic hypogonadism, a condition frequently associated with hypopituitarism and in which the TRT-related metabolic effects are combined with those deriving from concomitant administration of metabolically active pituitary-function replacement therapies. Methods. 15 men affected by postsurgical hypogonadotropic hypogonadism were evaluated before and after TRT. Cardiovascular risk factors (CVRFs), pituitary-dependent hormones, and AR gene CAG repeat polymorphism were considered. Results. Testosterone, insulin-like growth factor 1 (IGF-1), and estradiol were the only hormones, which varied significantly between the two phases. All CVRFs significantly improved after TRT. The number of CAG triplets was positively and significantly correlated with all the variations (Δ-) of CVRFs (except for a significant negative correlation with Δ-high-density lipoprotein); the opposite occurred between the latter and Δ-testosterone. No correlation between Δ-IGF-1 or estradiol and Δ-CVRFs was found. At multiple linear regression, after correction for Δ-testosterone, nearly all the associations between the number of CAG triplets and Δ-CVRFs were confirmed. Conclusions. In male postsurgical hypogonadotropic hypogonadism, shorter AR gene CAG tract length seems to yield greater metabolic improvement after TRT, independently of the effects of concomitant pituitary-function replacement therapies

Influence of Androgen Receptor Gene CAG and GGC Polymorphisms on Male Sexual Function: A Cross-Sectional Study

Background. No study has assessed the possible involvement of GGC androgen receptor (AR) polymorphism in sexual function. Our aim is to evaluate the association between CAG and GGC AR polymorphisms in this function. Methods. We retrospectively examined eighty-five outpatients. Clinical, biochemical, and genetic parameters were considered. Sexual assessment was performed using the International Index of Erectile Function (IIEF) which evaluates erectile function (EF), orgasmic function (OF), sexual desire (SD), intercourse satisfaction (IS), and overall satisfaction (OS). Results. In the whole sample, CAG repeats were inversely correlated with EF, OF, and total IIEF-15 score, whereas GGC tracts did not show any significant correlation with sexual function. CAG relationship with IIEF items retained significance only in the eugonadal but not in the hypogonadal cohort. On the other hand, GGC tracts were not found to be significantly correlated with IIEF variables in either eugonadal or hypogonadal subjects. In eugonadal subjects, logistic regression pointed out that a higher number of CAG triplets were associated with lower values of EF, OF, SD, OS, and total IIEF independently from other confounders. Conclusions. GGC polymorphism seems not to exert any influence on sexual function, whereas CAG polymorphism appears to affect sexual parameters only in eugonadal subjects

Short poly-glutamine repeat in the androgen receptor in New World monkeys

The androgen receptor mediates various physiological and developmental functions and is highly conserved in mammals. Although great intraspecific length polymorphisms in poly glutamine (poly-Q) and poly glycine (poly-G) regions of the androgen receptor in humans, apes and several Old World monkeys have been reported, little is known about the characteristics of these regions in New World monkeys. In this study, we surveyed 17 species of New World monkeys and found length polymorphisms in these regions in three species (common squirrel monkeys, tufted capuchin monkeys and owl monkeys). We found that the poly-Q region in New World monkeys is relatively shorter than that in catarrhines (humans, apes and Old World monkeys). In addition, we observed that codon usage for poly-G region in New World monkeys is unique among primates. These results suggest that the length of polymorphic regions in androgen receptor genes have evolved uniquely in New World monkeys

Androgen receptor (AR)-CAG trinucleotide repeat length and idiopathic male infertility

CAG trinucleotide repeats in androgen receptor (AR) gene encode a polyglutamine tract in AR N-terminal transactivation domain. Studies have been conducted to evaluate the effect of CAG repeat length on male infertility, which have yielded contradictory results. This study aimed to explore the number of AR-CAG repeats in 150 fertile controls and 150 idiopathic infertile men, divided into four azoospermia, oligozoospermia, asthenozoospermia, and teratozoospermia subgroups. In addition, a meta-analysis was conducted based on previous studies to assess the association of the mentioned variation with male infertility in recent years. Polymerase chain reaction (PCR) targeting followed by an electrophoresis on polyacrylamide gel was used for AR-CAG genotype detecting. Moreover, a systematic search was performed in PubMed, Web of Science, Science Direct, and Google Scholar databases to collect eligible studies for meta-analysis purpose. According to the results, a significant association was observed between increased length of AR-CAG polymorphism and male infertility (p< 0.0001). Furthermore, there were similar significant associations in the azoospermia (p= 0.048), asthenozoospermia (p= 0.013) and teratozoospermia (p= 0.002) subgroups. In addition, meta-analysis on forty studies showed a significant association between AR-CAG polymorphism in the overall analysis (SMD= 0.199, 95 % CI= 0.112-0.287, p<0.001) and the Caucasian subgroup (SMD= 0.151, 95 % CI= 0.040-0.263, p= 0.008). Our results elucidated that long stretches of CAG repeat might lead to AR dysfunction, contributing to male infertility especially in the Caucasian population

Genetic, environmental and life-style effects on androgen receptor function

Androgens regulate male reproductive function and their effects are mediated through the androgen receptor (AR). The AR gene contains a polymorphic CAG repeat, encoding a stretch of glutamines, affecting the transcriptional activity of the AR. Prostate specific antigen (PSA) is a downstream target and is commonly used in the screening of prostate cancer. The relationship between CAG number and male reproductive health has been suggested to be modulated by persistent organic pollutants (POPs). Humans are exposed mainly through food intake, but also from industrial processes and cigarette smoking. The dioxin-like POPs exert their effect through the aryl hydrocarbon receptor (AhR), shown to interact with the AR. The aims were to study the role of the CAG polymorphism on; AR activity and expression in the absence or presence of POPs; PSA concentration in serum and tissue; and reproductive parameters and hormones in men. It was also elucidated whether the CAG number could modify the effect of cigarette smoking on reproductive characteristics in men. The transactivation assay included a reporter gene with a human androgen responsive promoter. Cells were transfected with vectors having CAG numbers of 16, 22 or 28, representative of the human range. To explore the association between CAG number and reproductive outcome, an unprejudiced spline regression model with CAG number as a continuous variable was used, as well as a stratified model and in case of linear pattern, CAG number was investigated in a linear regression model. We found that the CAG variant with the median length had the highest AR activity, shown both in cell lines and prostate tissue, and as highest PSA concentration in younger and older men. The unprejudiced statistical analysis gave a better picture of the relationship between CAG number and reproductive outcomes, demonstrating a CAG-dependent effect on hormone levels. The CAG repeat also had a cell line- and dose-dependent modulating effect of POPs on AR activity and was negatively associated with semen volume in smoking men. To conclude, the median AR CAG number had the highest activity in vivo and in vitro. This pattern consisted even in the presence of POPs, indicating a stronger resistance for the median CAG length to these compounds compared to less common variants. The CAG number was also associated with reproductive hormone regulation and might modify the susceptibility of current cigarette smoking on semen volume in young men