Polymorphic variation in the androgen receptor gene: Association with risk of testicular germ cell cancer and metastatic disease

Cryptorchidism and testicular cancer in the dog: unresolved questions and challenges in translating insights from human studies†

Cryptorchidism, the failure of one or both testes to descend into the scrotum, and testicular cancer show a strong correlation in both dogs and humans. Yet, long-standing medical debates persist about whether the location of undescended testes directly causes testicular cancer in humans or if both conditions stem from a common origin. Although testicular cancer is a prevalent disease in dogs, even less is known about its cause and correlation with testicular descent in this species. This review investigates the relation between these two disorders in dogs, drawing insights from human studies, and examines key biomarkers identified thus far. In addition, it explores potential causal links, including the impact of temperature on maturing testicular cells and a potential shared genetic origin. Notably, this literature review reveals significant differences between men and dogs in reproductive development, histological and molecular features of testicular tumors, and the prevalence of specific tumor types, such as Sertoli cell tumors in cryptorchid dogs and germ cell tumors in humans. These disparities caution against using dogs as models for human testicular cancer research and underscore the limitations when drawing comparisons between species. The paper concludes by suggesting specific research initiatives to enhance our understanding of the complex interplay between cryptorchidism and testicular cancer in dogs.

Analysis of the CAG tract length in the Androgen Receptor gene in Mexican patients with nonsyndromic cryptorchidism

OBJECTIVES

Cryptorchidism is the most common genitourinary birth defect in live newborn males and is considered as an important risk factor for testicular germ cell tumors and infertility. The Androgen Receptor gene is important in this pathology due to its participation, mainly, in the inguinoscrotal phase of testicular descent. We determine the length of the CAG tract in the Androgen Receptor (AR) gene in Mexican patients with nonsyndromic cryptorchidism.

METHODS

One hundred and 15 males were included; of these, 62 had nonsyndromic cryptorchidism and 53 were healthy volunteers. DNA was extracted from a peripheral blood samples, subsequently, the CAG tract in exon 1 of AR gene was amplified by PCR and sequenced.

RESULTS

Mexican patients with nonsyndromic cryptorchidism presented 25.03 ± 2.58 repeats of CAG tract in the AR gene compared to 22.72 ± 3.17 repeats of CAG tract in Mexican healthy individuals (p≤0.0001; t value of 4.3). Furthermore, the deletion of codon 57 that corresponds to the deletion of a leucine residue at position 57 (Del L57) in the AR gene was found for the first time in a nonsyndromic cryptorchidism patient. This molecular alteration has been related previously to testicular germ cell tumor (TGCT).

CONCLUSIONS

The CAG tract in the AR gene is longer in patients with nonsyndromic cryptorchidism than in healthy individuals, supporting the association between this polymorphism of the AR gene and nonsyndromic cryptorchidism in the Mexican population.

State of the art of the environmental behaviour and removal techniques of the endocrine disruptor 3,4-dichloroaniline

In recent years, the presence of Endocrine Disrupting Chemicals (EDCs) in wastewater discharges from agricultural and industrial sources, ^[1] fresh- and estuarine-waters, as well as soils, has been reported in the literature. ^[2] Studies of adverse changes in wildlife, linked to environmental exposure to these substances, and the suggestion that humans could also be at similar risk of adverse health effects, ^[3-5] have raised concern for urgent action to understand and reduce such risks. 3,4-Dichloroaniline (3,4-DCA) has been recognized as an EDC, with regards to endocrine disruption data for both wildlife populations and human health. ^[5] 3,4-DCA is present in the environment as a product of the biodegradation of phenylurea and phenylcarbamate pesticides ^[6,7] ; furthermore, it can be introduced from industrial and municipal wastewater that is insufficiently purified, or via accidental spills. ^[8-10] Increasing concentrations of 3,4-DCA in soil and water are the result of its high persistence and accumulation, as well as its low biodegradability. ^[11,12] Hence, remediation techniques require in-depth study, especially when considering the low removal achieved by traditional activated sludge treatments, and the generation of carcinogenic trihalomethanes as a consequence of the chlorine oxidation methods frequently used in drinking water plants. ^[13] Fe⁰/H₂O₂ systems, photodegradation using doped TiO₂, and the use of dielectric barrier discharge reactors, seem to be the most promising techniques for the removal of 3,4-DCA from water.

Predictive value of GGN and CAG repeat polymorphisms of androgen receptors in testicular cancer: a meta-analysis

The risk of testicular cancer (TC) is markedly increased in subjects with androgen insensitivity, and previous studies have proposed that GGN and CAG repeats in androgen receptors (AR) could be related to the risk of TC. To evaluate the association between the length of GGN and CAG repeats in AR and TC, a meta-analysis involving 3255 TC cases and 2804 controls was performed. The results suggested that long GGN repeats are associated with an increased risk of TC compared with those < 23 [odds ratio (OR) = 1.22, 95% confidence interval (CI) = 1.05–1.41]; similarly, a subgroup analysis revealed that this association occurred in studies with case sizes > 200, and in the mid-latitude, and seminoma subgroups. The subgroup analysis based on populations, high-latitude, and seminomas/non-seminomas suggested that AR CAG repeat polymorphisms with > 25 and < 21 + > 25 repeats might confer a protective effect to the patients with TC (in the high-latitude subgroup analysis, for > 25 vs. 21–25: OR = 0.54, 95% CI = 0.41–0.70). In contrast, an increased risk of TC was observed for AR CAG repeat polymorphisms with > 25 and < 21 + > 25 repeats in the mid-latitude subgroup (for > 25 vs. 21–25: OR = 1.65, 95% CI = 1.09–2.50). In addition, no associations between the remaining subgroups and male infertility were observed. In short, this meta-analysis suggested that AR GGN and CAG repeat polymorphisms may be involved in the etiology of TC.

Exploring the molecular aspects associated with testicular germ cell tumors: a review

Testicular germ cell tumors (TGCTs) represent the most common solid tumors affecting young men. They constitute a distinct entity because of their embryonic origin and their unique biological behavior. Recent preclinical data regarding biological signaling machinery as well as genetic and epigenetic mechanisms associated with molecular patterns of tumors have contribute to explain the pathogenesis and the differentiation of TGCTs and to understand the mechanisms responsible for the development of resistance to treatment. In this review, we discuss the main genetic and epigenetic events associated with TGCTs development in order to better define their role in the pathogenesis of these tumors and in cisplatin-acquired resistance.

Hormonally active agents in the environment: a state-of-the-art review

After the Second World War, infatuation with modern products has exponentially widened the spectrum of chemicals used. Some of them are capable of hijacking the endocrine system by blocking or imitating a hormone and are referred to as hormonally active chemicals or endocrine disruptors. These are chemicals that the body was not designed for evolutionarily and they are present in every matrix of the environment. We are living in a chemical world where the exposures are ubiquitous and take place in combinations that can interact with the endocrine system and some other metabolic activities in unexpected ways. The complexity of interaction of these compounds can be understood by the fact that they interfere with gene expression at extremely low levels, consequently harming an individual life form, its offspring or population. As the endocrine system plays a critical role in many biological or physiological functions, by interfering body's endocrine system, endocrine disrupting compounds (EDCs) have various adverse effects on human health, starting from birth defects to developmental disorders, deadly deseases like cancer and even immunological disorders. Most of these compounds have not been tested yet for safety and their effects cannot be assessed by the available techniques. The establishment of proper exposure measurement techniques and integrating correlation is yet to be achieved to completely understand the impacts at various levels of the endocrine axis.

Risk of cancer in children, adolescents, and young adults with autistic disorder

OBJECTIVES

To investigate whether individuals with autism have an increased risk for cancer relative to the general population.

STUDY DESIGN

We enrolled patients with autistic disorder from the Taiwan National Health Insurance database in years 1997-2011. A total of 8438 patients diagnosed with autism were retrieved from the Registry for Catastrophic Illness Patients database. The diagnosis of cancers was also based on the certificate of catastrophic illness, which requires histological confirmation. The risk of cancer among the autism cohort was determined with a standardized incidence ratio (SIR).

RESULTS

During the observation period, cancer occurred in 20 individuals with autism, which was significantly higher than a total number of expected cancers with a SIR estimate of 1.94 (95% CI 1.18-2.99). The number of cancer in males was greater than the expected number with a SIR of 1.95 (1.11-3.16), but no excess risk was found for females with a SIR of 1.91 (0.52-4.88). Cancer developed more than expected in individuals age 15-19 years with the SIR of 3.58 (1.44-7.38), but did not differ in other age range groups. The number of cancers of genitourinary system was significantly in excess of the expected number (SIR 4.15; 95% CI 1.13-10.65), and increased risk was found in ovarian cancer with SIR of 9.21 (1.12-33.29).

CONCLUSIONS

Our study demonstrated that patients with autistic disorder have an increased risk of cancer.

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 <21 or >24 than stage I patients.

An oncofetal and developmental perspective on testicular germ cell cancer

Germ cell tumors (GCTs) represent a diverse group of tumors presumably originating from (early fetal) developing germ cells. Most frequent are the testicular germ cell cancers (TGCC). Overall, TGCC is the most frequent malignancy in Caucasian males (20-40 years) and remains an important cause of (treatment related) mortality in these young men. The strong association between the phenotype of TGCC stem cell components and their totipotent ancestor (fetal primordial germ cell or gonocyte) makes these tumors highly relevant from an onco-fetal point of view. This review subsequently discusses the evidence for the early embryonic origin of TGCCs, followed by an overview of the crucial association between TGCC pathogenesis, genetics, environmental exposure and the (fetal) testicular micro-environment (genvironment). This culminates in an evaluation of three genvironmentally modulated hallmarks of TGCC directly related to the oncofetal pathogenesis of TGCC: (1) maintenance of pluripotency, (2) cell cycle control/cisplatin sensitivity and (3) regulation of proliferation/migration/apoptosis by KIT-KITL mediated receptor tyrosine kinase signaling. Briefly, TGCC exhibit identifiable stem cell components (seminoma and embryonal carcinoma) and progenitors that show large and consistent similarities to primordial/embryonic germ cells, their presumed totipotent cells of origin. TGCC pathogenesis depends crucially on a complex interaction of genetic and (micro-)environmental, i.e. genvironmental risk factors that have only been partly elucidated despite significant effort. TGCC stem cell components also show a high degree of similarity with embryonic stem/germ cells (ES) in the regulation of pluripotency and cell cycle control, directly related to their exquisite sensitivity to DNA damaging agents (e.g. cisplatin). Of note, (ES specific) micro-RNAs play a pivotal role in the crossover between cell cycle control, pluripotency and chemosensitivity. Moreover, multiple consistent observations reported TGCC to be associated with KIT-KITL mediated receptor tyrosine kinase signaling, a pathway crucially implicated in proliferation, migration and survival during embryogenesis including germ cell development. In conclusion, TGCCs are a fascinating model for onco-fetal developmental processes especially with regard to studying cell cycle control, pluripotency maintenance and KIT-KITL signaling. The knowledge presented here contributes to better understanding of the molecular characteristics of TGCC pathogenesis, translating to identification of at risk individuals and enhanced quality of care for TGCC patients (diagnosis, treatment and follow-up).

Identification of a novel androgen receptor mutation in a family with multiple components compatible with the testicular dysgenesis syndrome

CONTEXT

Androgen signaling via the androgen receptor (AR) is essential for normal testis development and male reproductive functions. We describe a rare family with 3 males affected by a mild disorder of sex determination compatible with testicular dysgenesis syndrome (TDS), including subfertility, cryptorchidism, hypospadias, and testicular cancer, caused by a novel AR mutation.

OBJECTIVE

The aim of this study was to describe the phenotype of the affected males, characterize functionally the novel AR mutation, and discuss the significance of partial androgen insufficiency in the pathogenesis of TDS.

PARTICIPANTS

The proband, his first cousin, and a nephew underwent a detailed clinical investigation including genetic tests, whereas four female members of the family were tested for the specific AR mutation.

RESULTS

A novel AR mutation, c.2214T>G;p.Ile738Met, was identified in the affected family members. Functional analysis of the mutation in a gene-reporter assay showed a 50% reduction in AR-induced transcriptional activity. The affected males had elevated LH and T in accordance with decreased AR signaling. The histology and immunohistochemical profile of the testis tissue from the 2 patients with testicular cancer showed features consistent with insufficient testis development and TDS.

CONCLUSION

The presence of all hallmarks of TDS, including germ cell cancer, in a family with a novel AR mutation causing a partial decrease in AR function is in line with the concept that reduced androgen signaling may contribute to the development of TDS. It also seems consistent with the hypothesis that environmental factors interfering with this pathway can play a role in the pathogenesis of TDS.

Testicular cancer and cryptorchidism

The failure of testicular descent or cryptorchidism is the most common defect in newborn boys. The descent of the testes during development is controlled by insulin-like 3 peptide and steroid hormones produced in testicular Leydig cells, as well as by various genetic and developmental factors. While in some cases the association with genetic abnormalities and environmental causes has been shown, the etiology of cryptorchidism remains uncertain. Cryptorchidism is an established risk factor for infertility and testicular germ cell tumors (TGCT). Experimental animal models suggest a causative role for an abnormal testicular position on the disruption of spermatogenesis however the link between cryptorchidism and TGCT is less clear. The most common type of TGCT in cryptorchid testes is seminoma, believed to be derived from pluripotent prenatal germ cells. Recent studies have shown that seminoma cells and their precursor carcinoma in situ cells express a number of spermatogonial stem cell (SSC) markers suggesting that TGCTs might originate from adult stem cells. We review here the data on changes in the SSC somatic cell niche observed in cryptorchid testes of mouse models and in human patients. We propose that the misregulation of growth factors' expression may alter the balance between SSC self-renewal and differentiation and shift stem cells toward neoplastic transformation.

Population-based case-control study of recreational drug use and testis cancer risk confirms an association between marijuana use and nonseminoma risk

BACKGROUND

Testicular germ cell tumor (TGCT) incidence increased steadily in recent decades, but causes remain elusive. Germ cell function may be influenced by cannabinoids, and 2 prior epidemiologic studies reported that the use of marijuana may be associated with nonseminomatous TGCT. Here, the authors evaluate the relation between TGCTs and exposure to marijuana and other recreational drugs using a population-based case-control study.

METHODS

In total, 163 patients who were diagnosed with TGCT in Los Angeles County from December 1986 to April 1991 were enrolled, and 292 controls were matched on age, race/ethnicity, and neighborhood. Participants were asked about drug use by a structured, in-person interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression analysis adjusted for history of cryptorchidism; education; religiosity; and reported use of marijuana, cocaine, and amyl nitrite.

RESULTS

Compared with never use, ever use of marijuana had a 2-fold increased risk (OR, 1.94; 95% CI, 1.02-3.68), whereas ever use of cocaine had a negative association with TGCT (OR, 0.54; 95% CI, 0.32-0.91). Stratification on tumor histology revealed a specific association of marijuana use with nonseminoma and mixed histology tumors (OR, 2.42; 95% CI, 1.08-5.42).

CONCLUSIONS

A specific association was observed between marijuana use and the risk of nonseminoma and mixed tumors. To the authors' knowledge, this is the first report of a negative association between cocaine use and TGCT risk. The current results warrant mechanistic studies of marijuana's effect on the endocannabinoid system and TGCT risk and caution that recreational and therapeutic use of cannabinoids by young men may confer malignant potential to testicular germ cells.

Testicular germ cell tumors: biology and clinical update

PURPOSE OF REVIEW

This overview discusses several important developments in testicular germ cell tumors in the past year.

RECENT FINDINGS

Genomic studies continue to investigate gene expression as possible markers for disease relapse and chemotherapy resistance. Optimal treatment strategies for early-stage seminomas are evolving toward surveillance versus chemotherapy and away from radiation, and the role of retroperitoneal lymph node dissection in disseminated nonseminomatous cancers in complete remission is becoming less certain.

SUMMARY

Treatment and surveillance paradigms continue to be defined and refined for both early and late-stage disease as research in these areas continues and the data from multiple large studies mature.

Association of polymorphisms in genes encoding hormone receptors ESR1, ESR2 and LHCGR with the risk and clinical features of testicular germ cell cancer

Testicular germ cell cancer (TGCC) is the most common malignancy in young men. Genetic variants known to be associated with risk of TGCC only partially account for the observed familial risks. We aimed to identify additional polymorphisms associated with risk as well as histological and clinical features of TGCC in 367 patients and 214 controls. Polymorphisms in ESR2 (rs1256063; OR=0.53, 95% CI: 0.35-0.79) and LHCGR (rs4597581; OR=0.68, 95% CI: 0.51-0.89, and rs4953617; OR=1.88, 95% CI: 1.21-2.94) associated with risk of TGCC. Polymorphisms in ESR1 (rs9397080; OR=1.85, 95% CI: 1.18-2.91) and LHCGR (rs7371084; OR=2.37, 95% CI: 1.26-4.49) associated with risk of seminoma and metastasis, respectively. SNPs in ESR1 (rs9397080) and LHCGR (rs7371084) were predictors of higher LH levels and higher androgen sensitivity index in healthy subjects. The results suggest that polymorphisms in ESR1, ESR2 and LHCGR contribute to the risk of developing TGCC, histological subtype, and risk to metastasis.

Heterogenous effect of androgen receptor CAG tract length on testicular germ cell tumor risk: shorter repeats associated with seminoma but not other histologic types

Increasing rates of testicular germ cells tumors (TGCTs) overtime suggest that environmental factors are involved in disease etiology, but familial risk and genome-wide association studies implicate genetic factors as well. We investigated whether variation in the functional CAG(n) polymorphism in the androgen receptor (AR) gene is associated with TGCT risk, using data from a population-based family study. We estimated odds ratios (OR) and 95% confidence intervals (CI) for the association of CAG repeat length and TGCT risk using matched pairs logistic regression. Analyses of 273 TGCT case-mother pairs revealed no association between AR CAG repeat length and overall TGCT risk. However, risk of seminoma was significantly associated with shorter CAG repeat length [CAG 20-21 versus CAG ≤ 19: OR = 0.82 (95% CI: 0.43-1.58), CAG 22-23 versus CAG ≤ 19: OR = 0.39 (95% CI: 0.19-0.83) and CAG ≥ 24 versus CAG ≤ 19: OR = 0.42 (95% CI: 0.20-0.86)], with a highly significant trend over these four categories of decreasing CAG repeat length (P(trend) = 0.0030). This is the first report of a statistically significant association between AR CAG repeat length and seminoma risk, suggesting that increased AR transactivation may be involved in development of seminoma and/or progression of carcinoma in situ/intratubular germ cell neoplasia unclassified to seminoma. This result provides a rationale whereby androgenic environmental compounds could contribute to increases in TGCT incidence, and identifies for the first time a potential biological pathway influencing whether TGCTs achieve seminomatous versus nonseminomatous histology, a clinically and biologically important distinction.

Testicular germ cell tumours: predisposition genes and the male germ cell niche

Testicular germ cell tumours (TGCTs) of adults and adolescents are putatively derived from primordial germ cells or gonocytes. Recently reported genome-wide association studies implicate six gene loci that predispose to TGCT development. Remarkably, the functions of proteins encoded by genes within these regions bridge our understanding between the pathways involved in primordial germ cell physiology, male germ cell development and the molecular pathology of TGCTs. Furthermore, this improved understanding of the mechanisms underlying TGCT development and dissemination has clinical relevance for the management of patients with these tumours.