The 5α-Reductase Type II A49T and V89L High-Activity Allelic Variants are More Common in Men with Prostate Cancer Compared with the General Population

Unveiling the molecular cross-talk between piwi-interacting RNAs and steroid 5 alpha reductase type 2 in sperm dysfunction

OBJECTIVE

To investigate the correlation between piwi-interacting RNA (piRNA) expression and steroid 5 alpha reductase type 2 (SRD5A2) mRNA regulation in seminal fluid across various male infertility conditions (asthenozoospermia, oligozoospermia, and azoospermia).

DESIGN AND SUBJECTS

This study included 88 male participants aged 20-40 years, categorized into infertility and normozoospermic groups.

EXPOSURE

Seminal fluid analysis and RNA extraction were performed to quantify SRD5A2 mRNA and selected piRNAs (hsa-piR-002528, hsa-piR-017183, hsa-piR-023244, and hsa-piR-023338) using qRT-PCR.

MAIN OUTCOME MEASURES

Correlation analysis evaluated interactions between piRNA levels and SRD5A2 expression. Statistical significance was determined using analysis of variance and correlation coefficients.

RESULTS

Seminal Fluid Analysis: significant differences in seminal volume, sperm morphology, count, and motility were observed across infertility subtypes. Steroid 5 alpha reductase type 2 Expression: asthenozoospermia showed up-regulated SRD5A2 mRNA (Log2FC = 0.333), whereas oligozoospermia and azoospermia exhibited down-regulation (Log2FC = -0.470 and -0.688, respectively). Piwi-interacting RNA Expression: hsa-piR-002528 and hsa-piR-017183 were up-regulated in all infertility subtypes, whereas hsa-piR-023244 and hsa-piR-023338 exhibited subtype-specific expression patterns. Correlation Analysis: Steroid 5 alpha reductase type 2 mRNA negatively correlated with hsa-piR-002528 and hsa-piR-023338, suggesting regulatory interactions affecting sperm motility and count. Positive correlations were observed for hsa-piR-023244 in azoospermia, indicating potential roles in supporting spermatogenesis.

CONCLUSIONS

Altered piRNA profiles and SRD5A2 expression are associated with male infertility subtypes. These findings highlight the regulatory role of piRNAs in spermatogenesis and their potential as biomarkers and therapeutic targets for male infertility.

Genetic associations of prostate cancer in China: a systematic review

OBJECTIVES

In recent years, there has been a notable increase in the incidence and mortality rates of prostate cancer (PCa) in China, highlighting it as a significant public health issue. This study aimed to investigate the genetic association of PCa in China to better inform national disease management and medical resource allocation.

METHODS

A systematic literature review was conducted using 5 English databases (Web of Science, PubMed, Embase, Cochrane, Scopus) and 1 Chinese database (CNKI) to identify articles published from database inception to October 8, 2022, which reported the genetic associations of PCa in China.

RESULTS

Of the 11,195 articles retrieved, 41 were included in the review. A total of 116 different polymorphisms (including single nucleotide polymorphisms, deletions, insertions, and repeat lengths) in 58 genes were studied in Chinese populations. Among these, 37 out of 51 polymorphisms in 28 candidate genes such as BIRC5, C2orf43, COX-2, CYR61 (IGFBP10), DNMT1, DNMT3B, EXO1, FOXP4, and 7 unmapped SNPs were found to have either a positive or negative effect on PCa risk. However, 18 variants in 5 genes remain controversial across different studies. Additionally, 23 SNPs in 16 genes were reported to be associated with disease stage, Gleason score, PSA levels, PCa risk, and clinicopathological characteristics of PCa in China.

CONCLUSION

In Chinese populations, PCa risk and clinical features may result from individual genes, gene-gene interactions, and gene-environment interactions. These findings provide important insights into the relationship between genetic susceptibility and PCa risk in Chinese men.

A comprehensive systematic review of studies on the potential of A49T and V89L polymorphism in SRD5AR2 as high susceptibility gene association with benign prostate hyperplasia and prostate cancer

INTRODUCTION AND OBJECTIVES

Being the most common disease in aged men, the etiology of benign prostatic hyperplasia (BPH) is not fully defined. Recent studies have reported that the association between BPH and metabolic genes is still inconsistent. A gene connected with BPH is SRD5AR2, whose polymorphisms, A49T and V89L, have distinct enzyme activity. This systematic review examines SRD5AR2 polymorphisms within two alleles (A49T and V89L), assessing their roles as prognostic indicators of malignancy, and response to medication.

MATERIALS AND METHODS

We conducted a search on six different databases, including PubMed, Scopus, Wiley, ProQuest, Cochrane Central, and Science Direct using as string of keywords (BPH) AND [(rs523349) OR (V89L)] AND [(rs9282858) OR (A49T)]. We finally selected seven articles to be extracted. Quality appraisal of clinical trials was evaluated using the Joanna Briggs Institute Approach for systematic reviews.

RESULTS

We sorted nine clinical studies from various countries examining SRDA52 polymorphism and its association of BPH and prostate cancer. About V89L we found that the "LL" genotype, indicating reduced 5α-reductase activity, is linked to a lower BPH risk, while the "VV" genotype may slightly increase BPH risk. About A49T, compared to "AA" genotype, "AT" tends to be associated to higher risk in developing prostate cancer. A49T polymorphism does not show any effect on medical treatment while V89L showed a protective effect on the clinical progression of BPH when treated with 5a-reductase inhibitors, aadrenergic receptor antagonists, and alpha blockers.

CONCLUSIONS

SRD5A2 polymorphisms could be a good indicator for prognostic malignancy and a potential tool for personalized medicine of BPH. The findings strongly support the recommendation for further study about SRD5AR2 to enhance its use for screening and prevention and to optimize the medical treatment of BPH.

Benign prostatic hyperplasia genetic variants in Asians

The global prevalence of benign prostatic hyperplasia (BPH) is increasing annually, with a notably higher incidence in Asian populations. This condition can increase the risk of developing prostate cancer 2- to 12-fold, underscoring the critical need for comprehensive clinical guidelines and appropriate risk stratification testing. This review is the first to address the gap by focusing on genetic screening for risk stratification in Asians, followed by the development of pathophysiology based on the genetic variants identified. For example, the CYP17 gene, which plays a crucial role in testosterone synthesis and BPH progression, includes the CYP17 rs743572 C allele, a genetic variant that increases the risk of BPH by 1.58 times in Asians. Identifying such genetic variants can enable the tailoring of therapies to individual genetic profiles. Furthermore, this review provides new insights into the pathophysiology of BPH, suggesting that ethnicity may play a role in its progression, and explores genetic links between BPH and other diseases traditionally considered risk factors for BPH.

In silico and functional studies reveal novel loss-of-function variants of SRD5A2, but no variants explaining excess 5α-reductase activity

Androgens are steroid hormones essential for human male and female development. Steroid reductases 5α (SRD5As) are key enzymes in androgen biosynthesis. Mutations in the human SRD5A2 are known to cause loss-of-function and severe 46,XY undervirilization. Gain-of-function variants have been suggested in androgen excess syndromes, but have not been found so far. Therefore we searched for gain-of-function mutations in the human SRD5A2 gene which might explain hyperandrogenic disorders such as the polycystic ovary syndrome, premature adrenarche and prostate cancer. We screened databases for candidate variants and characterised them in silico with the help of a novel SRD5A2 model. We selected 9 coding SNPs (A49T, R50A, P106L, P106A, N122A, L167S, R168C, P173S, R227Q) that have not been described in manifesting individuals, and assessed their enzyme kinetic properties in HEK293 cells. SRD5A2 activity was assessed by conversion of testosterone (T), progesterone (Prog) and androstenedione (Δ4A) to their 5α-reduced metabolites. Variants R50A and P173S showed partial activity with substrates T (34% and 28%) and Δ4A (37% and 22%). With substrate Prog variants P106L, P106A, L167S and R168C in addition showed partial activity (15% to 64%). Functional testing of all other variants showed loss-of-function. As predicted in our in silico analysis, all coding SNPs affected enzyme activity, however none of them showed gain-of-function. Thus excess 5α-reductase activity might be rather regulated at the (post)-transcriptional and/or post-translational level. However through this work seven new coding SNPs were characterised which might be of clinical relevance. It is possible that individuals carrying these SNPs show a minor phenotype that is not yet identified.

A 5α-reductase (SRD5A2) polymorphism is associated with serum testosterone and sex hormone-binding globulin in men, while aromatase (CYP19A1) polymorphisms are associated with oestradiol and luteinizing hormone reciprocally

CONTEXT

Pituitary luteinizing hormone (LH) stimulates testicular production of testosterone (T) which is metabolized to dihydrotestosterone (DHT) by 5α-reductase and to oestradiol (E2) by aromatase. How the activity of population variants in these enzymes impacts on gonadal function is unclear. We examined whether polymorphisms in 5α-reductase (SRD5A2) and aromatase (CYP19A1) genes predict circulating sex hormone concentrations.

DESIGN

Cross-sectional analysis of 1865 community-dwelling men aged 50.4 ± 16.8 years.

MEASUREMENTS

Early morning sera assayed for T, DHT and E2 (mass spectrometry), and SHBG and LH (immunoassay). Two SRD5A2 and eleven CYP19A1 polymorphisms were analysed by PCR. Regression models were adjusted for age and cardiometabolic risk factors.

RESULTS

SRD5A2 polymorphism rs9282858 GA vs. GG was associated with higher serum T (+1.5 nmol/L, P < 0.001) and higher SHBG (+3.3 nmol/L, P = 0.001). CYP19A1 polymorphisms were associated with higher serum E2 and lower LH in reciprocal fashion, from which the two-copy haplotype rs10046 = T/rs2899470 = G/rs11575899 = I/rs700518 = G/rs17703883 = T was associated with higher E2 (63.4 vs. 56.5 pmol/L, P = 0.001) and lower LH (3.9 vs. 4.5 IU/L, P = 0.001) compared to null copies. Conversely, rs10046 = C/rs2899470 = T/rs11575899 = D/rs700518 = A/rs17703883 = C was associated with lower E2 (51.8 vs. 62.0 pmol/L, P = 0.001) and higher LH (5.7 vs. 3.9 IU/L, P < 0.001). These haplotypes were associated primarily with differences in E2 in men <65 years and LH in men ≥65 years.

CONCLUSIONS

A 5α-reductase polymorphism predicts circulating T and SHBG, while aromatase polymorphisms predict E2 and LH in reciprocal fashion. Age and aromatase polymorphisms interact to affect E2 and LH. How these functional polymorphisms impact on male reproductive and general health outcomes requires further study.

Association between SRD5A2 rs523349 and rs9282858 Polymorphisms and Risk of Benign Prostatic Hyperplasia: A Meta-Analysis

Objective: Previous studies have reported that rs523349 (V89L) and rs9282858 (A49T) polymorphisms in the gene 5α-reductase II (SRD5A2) are associated with the risk of benign prostatic hyperplasia (BPH), but different opinions have emerged. In view of distinct discrepancies among those findings, we performed this meta-analysis to ascertain a more accurate association between SRD5A2 rs523349 and rs9282858 polymorphisms and the risk of BPH. Methods: Studies investigating the association between SRD5A2 rs523349 and rs9282858 polymorphisms and susceptibility to BPH were searched from the databases of PubMed, Embase, Wanfang, and Chinese National Knowledge Infrastructure (CNKI).The strength of correlation was assessed by crude odds ratios (ORs) with their corresponding 95% confidence intervals (95% CIs). Moreover, subgroup analysis was conducted to further ascertain such relationship and investigate sources of heterogeneity. Results:SRD5A2 rs9282858 (A49T) polymorphism showed a significant correlation with increased BPH susceptibility under allele T vs.allele A genetic model (OR = 2.51, 95% CI = 1.29-4.88) in total analysis, and stratification analysis by ethnicity also revealed a similar association in Caucasian group under the same contrast. SRD5A2 rs523349 (V89L) polymorphism showed no significant role in BPH occurrence in total analysis, but its reducing and increasing effects on the disease risk were reflected in Caucasian and other-ethnicity subgroups, respectively, after stratification analysis by ethnicity. Conclusion: In conclusion, SRD5A2 rs9282858 polymorphism may elevate the susceptibility to BPH, while the polymorphism rs523349 may exert different influences on the disease in people of different ethnic lines.

Relationship between SRD5A2 rs9282858 polymorphism and the susceptibility of prostate cancer: A meta-analysis based on 20 publications

The pathogenetic mechanism of prostate cancer (PCa) has not been understood completely, and gene polymorphisms have been demonstrated to play a critical role in the course. It has been reported that rs9282858 polymorphism of steroid 5-α-reductase type 2 (SRD5A2) may affect the susceptibility of PCa, but some researches showed different results. We therefore carried out a meta-analysis to clarify this relationship.Relevant studies were identified through PubMed and Chinese National Knowledge Infrastructure databases concerning the association between SRD5A2 rs9282858 polymorphism and PCa. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were calculated to assess the strength of the association. Additionally, stratified analyses were performed based on ethnicity and source of control. Besides, heterogeneity test, sensitivity analysis, and publication bias evaluation were conducted in current meta-analysis as well.Ultimately, 20 publications incorporating 30 case-control studies were included in this meta-analysis, involving a total of 7300 cases and 7952 controls. The overall results demonstrated that SRD5A2 rs9282858 polymorphism was remarkably associated with increased susceptibility of PCa (TT vs. AA: OR = 4.08, 95% CI = 1.94-8.58; TT + AT vs. AA: OR = 1.28, 95% CI = 1.11-1.47; TT vs. AA + AT: OR = 4.44, 95% CI = 2.12-9.27; allele T vs. allele A: OR = 1.34, 95% CI = 1.17-1.54). After subgroup analyses by ethnicity and source of control, we also observed a similar trend in Latinos, other-ethnicity, population-based, and hospital-based groups under corresponding genetic models.Our findings indicate that SRD5A2 rs9282858 polymorphism may be a susceptible factor to PCa.

Association of SRD5A2 gene mutations with risk of hypospadias in the Iranian population

BACKGROUND

Hypospadias is one of the most common forms of congenital malformation of the male external genitalia worldwide. The ratio in the Iranian population is one in 250 live male births. The conversion of testosterone to dihydrotestosterone (DHT) in the presence of steroid 5α-reductase 2, which is encoded by SRD5A2 gene, plays an important role in the normal development of the male reproductive system.

METHODS

We examined whether SRD5A2 gene mutations (V89L and A49T polymorphisms) are associated with the risk of hypospadias in the Iranian population. We performed exons sequencing for SRD5A2 gene in 109 hypospadias patients.

RESULTS

We identified two new mutations in the subgroups of affected cases: including a substitution of the nucleotide T > A in the codon 73 [c.219T > A (p.Leu73_Ser74insHisPro)] and an insertion of an extra A nucleotide in the codon 77 [c.229insA* (p.Gly77*)]. Additionally, we performed PCR-RFLP for the two identified polymorphisms and revealed that V89L [OR = 5.8, 95% CI (3.8-8.8), p value < 0.001] and A49T [OR = 10.16, 95% CI (3.94-26.25), p value < 0.001] are significantly associated with hypospadias occurrence in patients. Our haplotype analysis further indicated that the Leu-Ala haplotype increases risk of hypospadias; conversely, the Val-Ala haplotype decreases the risk of hypospadias in the studied patients.

CONCLUSIONS

This study demonstrates that polymorphisms in the SRD5A2 gene could be considered as a risk factor for hypospadias disease emergence.

Genetic variation: effect on prostate cancer

The crucial role of androgens in the development of prostate cancer is well established. The aim of this review is to examine the role of constitutional (germline) and tumor-specific (somatic) polymorphisms within important regulatory genes of prostate cancer. These include genes encoding enzymes of the androgen biosynthetic pathway, the androgen receptor gene, genes that encode proteins of the signal transduction pathways that may have a role in disease progression and survival, and genes involved in prostate cancer angiogenesis. Characterization of deregulated pathways critical to cancer cell growth have lead to the development of new treatments, including the CYP17 inhibitor abiraterone and clinical trials using novel drugs that are ongoing or recently completed [1]. The pharmacogenetics of the drugs used to treat prostate cancer will also be addressed. This review will define how germline polymorphisms are known affect a multitude of pathways, and therefore phenotypes, in prostate cancer etiology, progression, and treatment.

Polymorphism of the SRD5A2 gene and the risk of prostate cancer

Androgens are actively involved in the development of the prostate gland and appear to be essential for prostate carcinogenesis. The product of the SRD5A2 gene, membrane‑bound steroid 5‑α‑reductase, type II enzyme, is key in testosterone metabolism. The present study explored the association between the SRD5A2 V89L gene polymorphism and the risk of developing prostate cancer. The study cohort consisted of 456 male Slovak patients, including 260 cases with histologically confirmed prostate cancer and 196 age‑matched controls without any clinically suspected infections of the prostate. Polymerase chain reaction-restriction fragment length polymorphism analysis was used to detect the SRD5A2 polymorphism on codon 89. Odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) for different allele variants were calculated in order to determine the association between the SRD5A2 V89L gene polymorphism and prostate cancer. The distribution of V89L variants in the control group was consistent with the Hardy‑Weinberg equilibrium (χ2 test, P=0.266) with a significant deviation in the case group (χ2 test, P=0.04). However, no association between the SRD5A2 polymorphism and an increased risk of developing prostate cancer was identified. When the wild type VV variant was used as a reference, the ORs for different allele variants ranged from 1.11 (95% CI 0.66‑1.87, P=0.70) for the LL genotype to 0.99 (95% CI 0.68‑1.46, P=0.99) for the LL + VL genotypes. No particular allele variant was identified to exhibit an increased capacity to promote the development of highly aggressive prostate cancer (Gleason ≥7) or induce carcinogenesis at an earlier onset (<65 years of age). It was confirmed that in the population studied, the SRD5A2 V89L polymorphism was not associated with the risk of prostate cancer and SRD5A2 was not shown to be a key gene involved in prostate cancer development. Published data indicate that a combination of multiple genetic changes are required for prostate cancer development, rather than a single gene change. Therefore, it was hypothesized that high-throughput genotyping may be more effective than single nucleotide polymorphism detection.

Genome-wide association studies on serum sex steroid levels

Even though the levels of circulating sex steroid hormones are to a large extent heritable, their genetic determinants are largely unknown. With the advent of genome-wide association studies (GWAS), much progress has been made and several genetic loci have been identified to be associated with serum levels of dehydroepiandrosterone sulfate, testosterone and sex hormone-binding globulin. The variants identified so far only explain a small amount of the overall heritability, but may help to elucidate the role of sex steroid hormones in common disorders such as hypogonadism, type 2 diabetes and hormone-sensitive cancers. This review provides an overview of the current state of knowledge of the genetic determinants of sex steroid hormones, with a focus on recent GWAS and brief directions for elucidating the remaining heritability.

Genetic variations in the androgen receptor are associated with steroid concentrations and anthropometrics but not with muscle mass in healthy young men

Objective

The relationship between serum testosterone (T) levels, muscle mass and muscle force in eugonadal men is incompletely understood. As polymorphisms in the androgen receptor (AR) gene cause differences in androgen sensitivity, no straightforward correlation can be observed between the interindividual variation in T levels and different phenotypes. Therefore, we aim to investigate the relationship between genetic variations in the AR, circulating androgens and muscle mass and function in young healthy male siblings.

Design

677 men (25–45 years) were recruited in a cross-sectional, population-based sibling pair study.

Methods

Relations between genetic variation in the AR gene (CAGn, GGNn, SNPs), sex steroid levels (by LC-MS/MS), body composition (by DXA), muscle cross-sectional area (CSA) (by pQCT), muscle force (isokinetic peak torque, grip strength) and anthropometrics were studied using linear mixed-effect modelling.

Results

Muscle mass and force were highly heritable and related to age, physical activity, body composition and anthropometrics. Total T (TT) and free T (FT) levels were positively related to muscle CSA, whereas estradiol (E₂) and free E₂ (FE₂) concentrations were negatively associated with muscle force. Subjects with longer CAG repeat length had higher circulating TT, FT, and higher E₂ and FE₂ concentrations. Weak associations with TT and FT were found for the rs5965433 and rs5919392 SNP in the AR, whereas no association between GGN repeat polymorphism and T concentrations were found. Arm span and 2D:4D finger length ratio were inversely associated, whereas muscle mass and force were not associated with the number of CAG repeats.

Conclusions

Age, physical activity, body composition, sex steroid levels and anthropometrics are determinants of muscle mass and function in young men. Although the number of CAG repeats of the AR are related to sex steroid levels and anthropometrics, we have no evidence that these variations in the AR gene also affect muscle mass or function.

MicroRNAs that affect prostate cancer: emphasis on prostate cancer in African Americans

Although concerted efforts have been directed toward eradicating health disparities in the United States, the disease and mortality rates for African American men still are among the highest in the world. We focus here on the role of microRNAs (miRNAs) in the signaling pathways of androgen receptors and growth factors that promote the progression of prostate cancer to more aggressive disease. We explore also how differential expression of miRNAs contributes to aggressive prostate cancer including that of African Americans.

Steroid 5-alpha-reductase type 2 (SRD5A2) V89L and A49T polymorphisms and sporadic prostate cancer risk: a meta-analysis

Steroid 5-α-reductase type 2 (SRD5A2) V89L and A49T polymorphisms are thought to play a crucial role in the androgen synthesis and metabolic pathway, but their associations with prostate cancer risk remain controversial. To provide a more precise estimation of the associations between V89L and A49T polymorphisms and prostate cancer risk, we performed a meta-analysis using all published case-control studies of prostate cancer since January 1995. We used odds ratio (OR) and its 95% confidence interval (CI) to assess the strength of the association under various genetic models in both overall and stratified analyses. We also calculated the false-positive report probability, the power of the current study, and the observed P value for significant findings. This analysis included 45 eligible studies of a total of 15,562 cases and 15,385 controls, in which no significant associations were found for the V89L polymorphisms under all genetic models. However, small excess prostate cancer risk was associated with the 49T allele in mixed populations compared with the 49A allele (OR = 1.24, 95% CI = 1.02-1.50), and similar results were observed in Caucasians (OR = 1.24, 95% CI = 1.01-1.53). The sensitivity analysis further strengthened the validity of these findings without publication bias. Although there was no overall association between V89L and prostate cancer risk, A49T might play a role in the etiology of prostate cancer among Caucasians. Additional large and well-designed studies are warranted to validate these findings.

Association of V89L SRD5A2 polymorphism with craving and serum leptin levels in male alcohol addicts

RATIONALE

A causal role of sex hormones in the onset and course of alcohol dependence is well established. We recently demonstrated that the genetics of the androgen receptor and aromatase relate to craving in alcohol addicts during withdrawal. This relationship involves the modulation of leptin, which affects the mesolimbic dopamine reward circuit. The steroid 5-α reductase 2 (SRD5A2) converts testosterone to dihydrotestosterone and thereby causes increased androgenic potency.

OBJECTIVES

In this study, we explored whether functionally relevant genetic polymorphisms in SRD5A2 (V89L, A49T, [TA](n)) are linked to alcohol addiction and craving.

METHODS AND RESULTS

We investigated 118 male alcohol-addicted inpatients admitted for withdrawal treatment and compared them to 50 healthy age- and body mass index-matched controls. The two groups did not differ in their allelic distributions. Subsequent analyses revealed an association between the V89L genotype and alcohol craving within the patient group (p < 0.05). Leptin accounted for 55 % of this relationship. Compared to VL and VV carriers, LL carriers had reduced serum leptin levels (p < 0.05) and lower levels of craving (p < 0.01). Furthermore, we observed an interaction between the V89L and the TTTAn aromatase polymorphisms (p < 0.05). No effects were found for A49T or (TA)(n).

CONCLUSIONS

These findings further support a crucial role of sex hormone biosynthetic genes and signaling in alcohol withdrawal. Craving is an accepted risk factor for alcohol relapse. Hence, these results might be helpful in predicting the outcomes of alcohol addicts after detoxification. With SRD5A2 inhibitors already in clinical use worldwide, this study may also guide future preventive and therapeutic strategies.

Androgen receptor GGC polymorphism and testosterone levels associated with high risk of prostate cancer and benign prostatic hyperplasia

Polymorphic GGC repeats in the androgen receptor (AR) gene can alter transactivation of androgen-responsive genes and increase the risk of benign prostatic hyperplasia (BPH) and prostate cancer (PCa). We investigated the association between GGC repeat length, testosterone levels and the risk of developing PCa and BPH in a population from southern Brazil. A sample comprising 130 PCa, 126 BPH and 88 control patients was evaluated. DNA was extracted from leukocytes and the AR gene was analyzed by fragment analysis. The hazard ratio (HR) was estimated. GGC mean length was not different between the three study groups. The risk of developing PCa in individuals with GGC > 19 was 3.300 (95 %CI 1.385-7.874) higher when compared to the GGC ≤ 19 group (p = 0.007). The risk of developing PCa and BPH in individuals with total testosterone levels <4 ng/mL was 2.799 (95 % CI 1.362-5.754). (p = 0.005) and 2.786 (95 % CI 1.470-5.280) (p = 0.002), respectively. Total testosterone levels in patients with GGC > 19 were significantly lower when compared to patients in the GGC ≤ 19 group. Our data suggest that the presence of a high number of polymorphic GGC repeats in the AR gene is associated with an increased risk of developing PCa and BPH, and that lower testosterone levels also increase the risk of developing these diseases.

Polymorphisms in androgen signaling pathway predisposing to prostate cancer

Prostate cancer is the most frequent male malignancy diagnosed in western countries and androgens are known to mediate key physiological processes in prostate tissue. Since endogenous androgens have long been considered to be risk factors for prostate cancer, genes involved in androgen biosynthesis and metabolism have been extensively studied. In this review, association of androgen pathway genes, their polymorphic sites and risk of prostate cancer in different ethnic backgrounds is addressed together with their use to predict susceptibility and clinical outcomes of prostate cancer patients. The effect of the polymorphisms seems vary in different patients, populations and ethnic backgrounds. To date it is evident that the association between androgen pathway gene polymorphisms and prostate cancer risk is complex and many of the results are characterized by irreproducibility, which can be attributed to a variety of biological, statistical and technical reasons. In the future, with increasing knowledge, developing technologies and new genomic biomarkers it likely becomes possible to better estimate the risk of prostate cancer, and distinguish indolent disease from aggressive based on molecular profiling, and the analysis of gene-gene and gene-environment interactions.

Decision tree-based modeling of androgen pathway genes and prostate cancer risk

BACKGROUND

Inherited variability in genes that influence androgen metabolism has been associated with risk of prostate cancer. The objective of this analysis was to evaluate interactions for prostate cancer risk by using classification and regression tree (CART) models (i.e., decision trees), and to evaluate whether these interactive effects add information about prostate cancer risk prediction beyond that of "traditional" risk factors.

METHODS

We compared CART models with traditional logistic regression (LR) models for associations of factors with prostate cancer risk using 1,084 prostate cancer cases and 941 controls. All analyses were stratified by race. We used unconditional LR to complement and compare with the race-stratified CART results using the area under curve (AUC) for the receiver operating characteristic curves.

RESULTS

The CART modeling of prostate cancer risk showed different interaction profiles by race. For European Americans, interactions among CYP3A43 genotype, history of benign prostate hypertrophy, family history of prostate cancer, and age at consent revealed a distinct hierarchy of gene-environment and gene-gene interactions, whereas for African Americans, interactions among family history of prostate cancer, individual proportion of European ancestry, number of GGC androgen receptor repeats, and CYP3A4/CYP3A5 haplotype revealed distinct interaction effects from those found in European Americans. For European Americans, the CART model had the highest AUC whereas for African Americans, the LR model with the CART discovered factors had the largest AUC.

CONCLUSION AND IMPACT

These results provide new insight into underlying prostate cancer biology for European Americans and African Americans.

Meta-analysis of three polymorphisms in the steroid-5-alpha-reductase, alpha polypeptide 2 gene (SRD5A2) and risk of prostate cancer

The steroid-5-alpha-reductase, alpha polypeptide 2 (SRD5A2) gene plays a crucial role in androgen metabolism pathway in human prostate. It encodes SRD5A2 enzyme, which catalyses testosterone to dihydrotestosterone (DHT). DHT is the main active structure binding with androgen receptor (AR). After the activation of AR, it further regulates a series of target genes in androgen metabolism pathway. However, no clear consensus has been reached on the association between the SRD5A2 V89L, A49T and TA repeat polymorphisms and prostate cancer (PCa) risk. Thus, we performed a meta-analysis of 31 association studies with 14,726 PCa cases and 15,802 controls. We found no association between PCa and 89L compared with 89V allele [odds ratio (OR) = 1.02, 95% confidence interval (CI) 0.98-1.06, P(heterogeneity) = 0.44]. The 49T allele showed a significantly elevated effect on the high stage (Stages III-IV) of PCa risk both under the dominant genetic model (OR = 2.13, 95% CI 1.44-3.15, P(heterogeneity) = 0.65) and in the contrast T versus A allele (OR = 2.06, 95% CI 1.41-3.02, P(heterogeneity) = 0.69). There was a significantly decreased association between PCa and long TA repeat as compared versus short TA repeat (OR = 0.86, 95% CI 0.74-1.00, P(heterogeneity) = 0.79). No significant between-study heterogeneity was found in all subjects under four genetic models (dominant model, recessive model, allele comparison and homozygosity comparison) for these three polymorphisms, respectively, so the fixed effects model was used to pool the result. Our result indicated that carriers of 49T might improve the risk of PCa in higher stages (Stages III-IV), carriers of long TA repeat might decrease the risk of PCa and 89L may not be an important risk factor for PCa. However, due to the limited sample sizes, this meta-analysis did not achieve sufficiently conclusive results. Still more well-designed studies should be performed to clarify the role of these three polymorphisms in the development of PCa.

SRD5A2 V89L polymorphism and prostate cancer risk: a meta-analysis

BACKGROUND

Increasing studies investigating the association between steroid 5-alpha reductase type II gene polymorphism at codon 89 (SRD5A2 V89L) and susceptibility to prostate cancer (PCa) confer inconsistent results. To precisely estimate the relationship with more statistical power, a meta-analysis was performed.

METHODS

A comprehensive search was conducted to identify all case-control studies investigating such an association. Odds ratio (OR) and its 95% confidence interval (CI) were used to evaluate the size effect.

RESULTS

Twenty-five eligible reports were identified including 8,615 cases/9,089 controls in 33 comparisons. In overall analysis, no significant associations were found in all genetic models. Subgroup analyses by ethnicity revealed that small excess PCa risks were observed in dominant model (OR, 1.11; 95% CI, 1.03-1.19 for (LL + VL) vs. VV; P < 0.01; P(heterogeneity) = 0.49) and L allele frequency comparison (OR, 1.09; 1.03-1.15 for L allele frequency; P < 0.01; P(heterogeneity) = 0.07) in Europeans. Meanwhile, SRD5A2 V89L polymorphism was significantly associated with an increased PCa risk in men aged < or =65 under the co-dominant (OR, 1.70; 95% CI, 1.09-2.66 for LL vs. VV; P = 0.02; P(heterogeneity) = 0.31) and recessive (OR, 1.75; 95% CI, 1.14-2.68 for LL vs. (VV + VL); P = 0.01; P(heterogeneity) = 0.12) models. However, no significant associations were found in Asians and Africans.

CONCLUSIONS

Our study suggests SRD5A2 V89L polymorphism could play a low-penetrant role in PCa risk among Europeans and individuals younger than 65 years. Additional well-designed studies are warranted to validate these findings.

Steroid 5-{alpha}-reductase Type 2 (SRD5a2) gene polymorphisms and risk of prostate cancer: a HuGE review

Steroid 5-alpha-reductase type 2 (SRD5a2) is a critical enzyme in androgen metabolism. Two polymorphisms in the SRD5a2 gene, V89L (rs523349) and A49T (rs9282858), have been studied for associations with prostate cancer risk, with conflicting results. The authors conducted a systematic review and meta-analysis (1997-2007) to examine these associations and compared the results with findings from genome-wide association studies of prostate cancer. The meta-analysis included 24 case-control studies (10,088 cases and 10,120 controls for V89L and 4,998 cases and 5,451 controls for A49T). The authors found that prostate cancer was not associated with V89L (L allele vs. V allele: odds ratio = 0.99, 95% confidence interval: 0.94, 1.05) and was probably not associated with A49T (T allele vs. A allele: odds ratio = 1.10, 95% confidence interval: 0.86, 1.40). These results could have been distorted by spectrum-of-disease bias, convenience sampling of cases and controls, genotype misclassification, and/or confounding. Neither V89L nor A49T was included in microarray chips used for published genome-wide association studies. Analysis of well-designed population-based studies with pathway-based arrays containing common genetic variants could be useful for identifying genetic factors in prostate cancer.

The SRD5A2 V89L polymorphism is associated with severity of disease in men with early onset prostate cancer

BACKGROUND

Emerging evidence indicates that testosterone (T), and not dihydrotestosterone (DHT), is the most relevant androgen that promotes carcinogenesis in the prostate. Steroid 5-alpha reductase type II (SRD5A2) catalyzes the irreversible conversion of T to DHT in male reproductive organs. Because the SRD5A2 gene is highly polymorphic at codon 89, two SRD5A2 isoforms are expressed that differ in K(m) and V(max) values. The more common and rapid catalytic isoform contains a valine residue at position 89; the slower-catalytic variant contains leucine at this position.

METHODS

Thirty-three men with early onset prostate cancer (PCa) were genotyped for the SRD5A2 V89L substitution and other polymorphisms in genes encoding receptors or enzymes that play important roles in pathways of steroid metabolism to ascertain if they were associated with standard clinical measures of disease progression at the time of diagnosis.

RESULTS

The expression of at least one SRD5A2 leucine allele in young men with PCa was associated with more significant disease at the time of presentation, as was defined by pretreatment PSA level, clinical staging and Gleason score when compared with affected subjects harboring the more common SRD5A2 valine variant. A dosage effect of a single leucine allele was evident in heterozygotes, as values of their clinical and pathological variables were consistently situated between the extremes of the homozygous V or L phenotypes.

CONCLUSION

The SRD5A2 leucine isoform appears to be acting in a dose-dependent manner as a significant disease-modifying factor in young men diagnosed with PCa.

Is there evidence of a relationship between benign prostatic hyperplasia and prostate cancer? Findings of a literature review

CONTEXT

More than half the male population aged >50 yr have histologic evidence of benign prostatic hyperplasia (BPH), while prostate cancer (PCa) is among the most common male cancers according to recent registry data. Understanding the aetiologies of both conditions is crucial to reduce the resulting burden of mortality and morbidity.

OBJECTIVE

This review aims to examine the available data on the epidemiology, pathology, risk factors, and genetic markers involved in BPH and PCa; to discuss their clinical implications for management of both conditions; and to discuss their implications for PCa prevention. Our primary objective was to clarify the relationship between BPH and PCa by bringing together evidence from diverse areas of research.

EVIDENCE ACQUISITION

The primary source of data was PubMed, which was searched using Boolean strategies and by scanning lists of related articles. We also examined secondary sources from reference lists of retrieved articles and data presented at recent congresses.

EVIDENCE SYNTHESIS

Accumulating evidence suggests that BPH and PCa share important anatomic, pathologic, and genetic links in addition to the well-established epidemiologic association between these conditions. We also found data that suggest interactions between apparently diverse factors, such as dihydrotestosterone levels and inflammation. Recent publications support the hypothesis that both BPH and PCa are part of the metabolic syndrome, while inflammation is emerging as a major contributor to the development of both BPH and PCa. Although many of the findings are preliminary and require further research, they offer new insight into the mechanisms of disease underlying the development of BPH and PCa.

CONCLUSIONS

Available data suggest that epidemiologic and pathologic links exist between BPH and PCa. Evidence of links between the conditions and contributory factors may offer common preventative strategies for BPH and PCa and common therapeutic approaches to their management.

Androgens and the molecular epidemiology of prostate cancer

PURPOSE OF REVIEW

Despite clinical and experimental evidence that show androgens are important in prostate carcinogenesis, epidemiologic studies of serum androgens have been inconclusive. In this review, we summarize the current state of the literature and provide insights and direction for epidemiologic research on androgens and prostate cancer.

RECENT FINDINGS

To date, data on serum androgens in prostate cancer remain inconclusive. Large studies on variants in some androgen-metabolizing genes [SRD5A2, CYP17A1, and hydroxysteroid dehydrogenase (HSD)17B1] do not show a convincing links to prostate cancer, though there are insufficient data to draw conclusions on other genes related to androgen metabolism, including UDP-glycosyltransferases (UGT), sulfotransferases (SULT), CYP3A, and estrogen-related genes. There is some evidence, although controversial, suggesting that select variants may confer risk to certain subtypes of prostate cancer. The most notable finding in 2007 is the highly reproducible link between the chromosome 8q24 risk region and prostate cancer susceptibility.

SUMMARY

Besides the link between the 8q24 region and prostate cancer risk, population studies do not convincingly show that polymorphisms in androgen metabolism genes are associated with prostate cancer risk. Large epidemiologic studies with comprehensive gene coverage and reliable exposure data are needed to clarify further the role of androgens and their related genes in prostate cancer.

No association between the SRD5A2 gene A49T missense variant and prostate cancer risk: lessons learned

The steroid 5-alpha reductase type II gene (SRD5A2) encodes the enzyme which converts testosterone (T) to the more active androgen dihydrotestosterone. A non-synonymous single-nucleotide polymorphism, A49T (rs9282858), in SRD5A2 has been implicated in prostate cancer risk; however, results have been inconsistent. In 1999, we reported a strong association between the A49T variant and prostate cancer risk among African-Americans and Latinos in the Hawaii-Los Angeles Multiethnic Cohort (MEC). We report here an updated analysis of MEC data including the five major ethnic groups of the MEC, an increased sample size, improved genotyping technology and a comprehensive meta-analysis of the published literature. We found a non-statistically significant positive association between prostate cancer risk and carrying either the AT or TT genotype [odds ratio (OR) = 1.16, 95% confidence interval (CI) 0.79-1.69] in the MEC. This finding is in contrast to our previous results of ORs of 3.28 and 2.50 for the association between prostate cancer risk and the variant in African-American and Latino men, respectively; this can be accounted for by genotyping error in our earlier study. Meta-analysis of the published literature, including the current MEC data, shows a summary OR of 1.13 (95% CI 0.95-1.34) for the A49T variant with prostate cancer risk among sporadic, unselected cases. After evaluating more than 6000 cases and 6000 controls, there is little evidence of a role for the SRD5A2 A49T variant in prostate cancer risk. Overall, this report highlights the importance of rigorous genotyping quality control measures and replication efforts in genetic association studies.

Low-Activity V89L Variant in SRD5A2 Is Associated with Aggressive Prostate Cancer Risk: An Explanation for the Adverse Effects Observed in Chemoprevention Trials Using 5-Alpha-Reductase Inhibitors

OBJECTIVE

The 5-alpha-reductase type 2 (5A2) enzyme catalyses the irreversible conversion of testosterone to dihydrotestosterone, the most active androgen in the prostate. This key enzyme in prostate gland physiopathology has recently been targeted by using inhibitors for chemoprevention of prostate cancer. However, some controversies have arisen by the observation of greater than expected high-grade tumours in men diagnosed with prostate cancer in the finasteride chemoprevention trial. To help understand the impact of prolonged exposure to low 5A2 activity on prostate cancer risk, we analysed the rather common genetic V89L polymorphism, which has previously been well characterised functionally for determining low enzymatic activities.

METHODS

The study was performed on 1605 white Caucasian French men categorised in 803 patients with prostate adenocarcinoma and 802 matched healthy male controls. The different alleles and genotypes were analysed according to case-control status and the aggressiveness pattern of the tumours.

RESULTS

The V89L amino acid substitution leading to the homozygous genotype LL increased the risk of clinically significant disease (odds ratio [OR]=1.89, 95% confidence interval (%95 CI), 1.07-2.74; p=0.0017) and was also associated with the most aggressive patterns of the disease (OR=2.56, 95%CI, 1.41-4.63; p=0.002).

CONCLUSIONS

Our data confirm in a large and homogeneous Caucasian French population that the low-activity V89L variant is associated with an increased risk of aggressive prostate cancer. These results corroborate that long-term exposure to 5A2 inhibitors (chemoprevention) must be evaluated in terms of risk of prostate cancer adverse effects.

Genomic biomarkers, androgen pathway and prostate cancer

Prostate cancer is the most frequent male malignancy diagnosed in western countries and the second leading cause of cancer-related deaths. The growth and function of the prostate gland depends on androgens. Owing to the importance of androgens in prostate development, genes involved in androgen biosynthesis and metabolism have been extensively studied. In this review, we address recent progress toward the use of inherited and acquired genetic variants to predict susceptibility and clinical outcomes of prostate cancer patients. Many of these genetic variants involve several genes related to the biosynthesis and metabolism of androgens, such as steroid-5-α-reductase, α polypeptide 2 (SRD5A2), cytochrome P450 (CYP)19A1, CYP17A1, hydroxy-δ-5-steroid dehydrogenase, 3 β- and steroid δ-isomerase 2 (HSD3B2) and androgen receptor (AR). With increasing knowledge, it may be possible to distinguish indolent from aggressive prostate tumors by molecular fingerprinting. Furthermore, with the emergence of new investigative tools, such as microarray platforms and comparative genomic hybridization (CGH) array, a variety of new genomic biomarkers will be available in the future to provide accurate prognostic and monitoring solutions for individualized patient care.

Polymorphisms in genes regulating androgen activity among prostate cancer low-risk Inuit men and high-risk Scandinavians

In Greenland, with a male population of approximately 30 000 individuals, the incidence of prostate cancer is extremely low with only three cases described during the period 1988-1997. Polymorphisms related to high androgen metabolism and/or response in the 5alpha-reductase type 2 (SRD5A2) and the androgen receptor (AR) genes, respectively, have been linked to prostate cancer. Our objective was to analyse whether the distribution of these polymorphisms differed between the prostate cancer low-risk population from Greenland and the relatively high-risk Swedish male population. The SRD5A2 polymorphisms A49T, V89L and R227Q, and the CAG and GGN repeats in the AR gene were genotyped in leucocyte DNA from 196 Greenlanders and 305 Swedish military conscripts. All subjects had the wild-type R/R genotype of the R227Q marker. The high-activity variants A49T A/T and V89L V/V occurred less frequently (2% vs. 5%, p = 0.048 and 33% vs. 46%, p = 0.0027) in Greenland compared with Sweden, whereas the low-activity L/L genotype was more frequent in Greenland (24% vs. 13%, p = 0.0024). Greenlanders also had longer AR CAG repeats than the Swedish population (median 24 vs 22, p < 0.0005). Greenlanders also had a higher frequency of the GGN = 23 allele (85% vs. 54%, p < 0.0001). Our results suggest that Greenlanders are genetically predisposed to a lower activity in testosterone to 5alpha-dihydrotestosterone turnover and to lower AR activity, which, at least partly, could explain their low incidence of prostate cancer.

The Association of 5α-Reductase II (SRD5A2) and 17 Hydroxylase (CYP17) Gene Polymorphisms with Prostate Cancer Patients in The Turkish Population

To date, research has led to the invention of multiple genes and their single nucleotide polymorphisms (SNPs) and environmental factors that influence the prostate cancer (PCa) pathogenesis. Therefore, the genes involved in these pathways are candidates for PCa predisposition. It is thought that polymorphisms of 5alpha-reductase II (SRD5A2) and 17 hydroxylase (CYP17) genes are likely to increase susceptibility. The aim of this study was to investigate the risk association of SRD5A2 and CYP17 gene polymorphisms in the development and progression of PCa in the Turkish population. In this study, 100 PCa patients and 105 healthy controls were studied. SRD5A2 and CYP17 gene polymorphisms were determined by real-time PCR and polymerase chain reaction-restriction length polymorphisms (PCR-RFLP) techniques. First, the AT and TT genotypes of SRD5A2 gene at codon 49 were not observed. Second, there was no significant association between the polymorphisms at codon 89 and the risk of PCa. Third, in the CYP17 gene, the A1A1 genotype is more common (46%) in cases than controls (32.4%). The odds ratios (ORs) of the A1A1 genotype was found at 1.69 (95% confidence interval [CI], 0.77-3.74) compare with the A2A2 genotype. Genotyping results of the SRD5A2 and CYP17 genes were also analyzed in relation to prostate-specific antigen (PSA) levels, Gleason score (GS), and tumor stage, but no statistically significant difference was observed (P > 0.05). Finally, we conclude that there was no evidence of an association between CYP17 (P = 0.134) and SRD5A2 (P = 0.784) polymorphism and PCa risk in the Turkish population.

5α-Reductase type 2 gene variant associations with prostate cancer risk, circulating hormone levels and androgenetic alopecia

Controversy exists over the significance of associations between the SRD5A2 (5alpha-reductase type 2) polymorphisms, A49T and V89L, and risk of prostate cancer. These potentially functional polymorphisms may alter life-long exposure to androgens with subsequent effects on male health and aging. The aim of this study was to examine the association of these variants with prostate cancer risk, plasma hormone levels and androgenetic alopecia. Subjects include 827 cases and 736 controls from an Australian population-based case-control study of prostate cancer. Information on prostate cancer risk factors and patterns of balding were collected. Plasma levels of testosterone, 3alpha-diol glucuronide (3alpha-diolG), dehydroepiandrosterone sulfate, androstenedione, sex hormone-binding globulin and estradiol were measured for controls. No associations with the V89L polymorphism were found. Carriers of the rarer A49T A allele were at a 60% higher risk of prostate cancer (OR = 1.60; 95% CI 1.09-2.36; p = 0.02) and 50% lower risk of vertex and frontal balding (p = 0.03) compared with men homozygous for the more common G allele. Although we found little evidence of association between this variant and plasma levels of 5 measured androgens, circulating 3alpha-diolG levels were 34% lower in A49T A allele carriers (p < 0.0001). Our study provides evidence that the SRD5A2 A49T A variant is associated with an increased risk of prostate cancer, lower levels of circulating 3alpha-diolG and decreased risk of baldness. These findings raise important questions with respect to previous assumptions concerning hormonal influences on prostate cancer risk in ageing males.