Germline mutations in HOXB13 and prostate-cancer risk

Identification and characterization of locus-specific methylation patterns within novel loci undergoing hypermethylation during breast cancer pathogenesis

Introduction

Despite similar clinical and pathological features, large numbers of breast cancer patients experience different outcomes of the disease. This, together with the fact that the incidence of breast cancer is growing worldwide, emphasizes an urgent need for identification of new biomarkers for early cancer detection and stratification of patients.

Methods

We used ultrahigh-resolution microarrays to compare genomewide methylation patterns of breast carcinomas (n = 20) and nonmalignant breast tissue (n = 5). Biomarker properties of a subset of discovered differentially methylated regions (DMRs) were validated using methylation-sensitive high-resolution melting (MS-HRM) in a case–control study on a panel of breast carcinomas (n = 275) and non-malignant controls (n = 74).

Results

On the basis of microarray results, we selected 19 DMRs for large-scale screening of cases and controls. Analysis of the screening results showed that all DMRs tested displayed significant gains of methylation in the cancer tissue compared to the levels in control tissue. Interestingly, we observed two types of locus-specific methylation, with loci undergoing either predominantly full or heterogeneous methylation during carcinogenesis. Almost all tested DMRs (17 of 19) displayed low-level methylation in nonmalignant breast tissue, independently of locus-specific methylation patterns in cases.

Conclusions

Specific loci can undergo either heterogeneous or full methylation during carcinogenesis, and loci hypermethylated in cancer frequently show low-level methylation in nonmalignant tissue.

Fine-mapping the HOXB region detects common variants tagging a rare coding allele: evidence for synthetic association in prostate cancer

The HOXB13 gene has been implicated in prostate cancer (PrCa) susceptibility. We performed a high resolution fine-mapping analysis to comprehensively evaluate the association between common genetic variation across the HOXB genetic locus at 17q21 and PrCa risk. This involved genotyping 700 SNPs using a custom Illumina iSelect array (iCOGS) followed by imputation of 3195 SNPs in 20,440 PrCa cases and 21,469 controls in The PRACTICAL consortium. We identified a cluster of highly correlated common variants situated within or closely upstream of HOXB13 that were significantly associated with PrCa risk, described by rs117576373 (OR 1.30, P = 2.62×10(-14)). Additional genotyping, conditional regression and haplotype analyses indicated that the newly identified common variants tag a rare, partially correlated coding variant in the HOXB13 gene (G84E, rs138213197), which has been identified recently as a moderate penetrance PrCa susceptibility allele. The potential for GWAS associations detected through common SNPs to be driven by rare causal variants with higher relative risks has long been proposed; however, to our knowledge this is the first experimental evidence for this phenomenon of synthetic association contributing to cancer susceptibility.

Risk-based prostate cancer screening: who and how?

The purpose of this review is to identify clinical risk factors for prostate cancer and to assess the utility and limitations of our current tools for prostate cancer screening. Prostate-specific antigen is the single most important factor for identifying men at increased risk of prostate cancer but is best assessed in the context of other clinical factors; increasing age, race, and family history are well-established risk factors for the diagnosis of prostate cancer. In addition to clinical risk calculators, novel tools such as multiparametric imaging, serum or urinary biomarkers, and genetic profiling show promise in improving prostate cancer diagnosis and characterization. Optimal use of existing and future tools will help alleviate the problems of overdiagnosis and overtreatment of low-risk prostate cancer without reversing the substantial mortality declines that have been achieved in the screening era.

A prostate cancer susceptibility allele at 6q22 increases RFX6 expression by modulating HOXB13 chromatin binding

Genome-wide association studies have identified thousands of SNPs associated with predisposition to various diseases, including prostate cancer. However, the mechanistic roles of these SNPs remain poorly defined, particularly for noncoding polymorphisms. Here we find that the prostate cancer risk-associated SNP rs339331 at 6q22 lies within a functional HOXB13-binding site. The risk-associated T allele at rs339331 increases binding of HOXB13 to a transcriptional enhancer, conferring allele-specific upregulation of the rs339331-associated gene RFX6. Suppression of RFX6 diminishes prostate cancer cell proliferation, migration and invasion. Clinical data indicate that RFX6 upregulation in human prostate cancers correlates with tumor progression, metastasis and risk of biochemical relapse. Finally, we observe a significant association between the risk-associated T allele at rs339331 and increased RFX6 mRNA levels in human prostate tumors. Together, our results suggest that rs339331 affects prostate cancer risk by altering RFX6 expression through a functional interaction with the prostate cancer susceptibility gene HOXB13.

Translating genetic risk factors for prostate cancer to the clinic: 2013 and beyond

Prostate cancer (PrCa) is the most commonly diagnosed cancer in the male UK population, with over 40,000 new cases per year. PrCa has a complex, polygenic predisposition, due to rare variants such as BRCA and common variants such as single nucleotide polymorphisms (SNPs). With the introduction of genome-wide association studies, 78 susceptibility loci (SNPs) associated with PrCa risk have been identified. Genetic profiling could risk-stratify a population, leading to the discovery of a higher proportion of clinically significant disease and a reduction in the morbidity related to age-based prostate-specific antigen screening. Based on the combined risk of the 78 SNPs identified so far, the top 1% of the risk distribution has a 4.7-times higher risk of developing PrCa compared with the average of the general population.

Comprehensive functional annotation of 77 prostate cancer risk loci

Genome-wide association studies (GWAS) have revolutionized the field of cancer genetics, but the causal links between increased genetic risk and onset/progression of disease processes remain to be identified. Here we report the first step in such an endeavor for prostate cancer. We provide a comprehensive annotation of the 77 known risk loci, based upon highly correlated variants in biologically relevant chromatin annotations--we identified 727 such potentially functional SNPs. We also provide a detailed account of possible protein disruption, microRNA target sequence disruption and regulatory response element disruption of all correlated SNPs at r(2) ≥ 0.88%. 88% of the 727 SNPs fall within putative enhancers, and many alter critical residues in the response elements of transcription factors known to be involved in prostate biology. We define as risk enhancers those regions with enhancer chromatin biofeatures in prostate-derived cell lines with prostate-cancer correlated SNPs. To aid the identification of these enhancers, we performed genomewide ChIP-seq for H3K27-acetylation, a mark of actively engaged enhancers, as well as the transcription factor TCF7L2. We analyzed in depth three variants in risk enhancers, two of which show significantly altered androgen sensitivity in LNCaP cells. This includes rs4907792, that is in linkage disequilibrium (r(2) = 0.91) with an eQTL for NUDT11 (on the X chromosome) in prostate tissue, and rs10486567, the index SNP in intron 3 of the JAZF1 gene on chromosome 7. Rs4907792 is within a critical residue of a strong consensus androgen response element that is interrupted in the protective allele, resulting in a 56% decrease in its androgen sensitivity, whereas rs10486567 affects both NKX3-1 and FOXA-AR motifs where the risk allele results in a 39% increase in basal activity and a 28% fold-increase in androgen stimulated enhancer activity. Identification of such enhancer variants and their potential target genes represents a preliminary step in connecting risk to disease process.

The genetic epidemiology of prostate cancer and its clinical implications

Worldwide, familial and epidemiological studies have generated considerable evidence of an inherited component to prostate cancer. Indeed, rare highly penetrant genetic mutations have been implicated. Genome-wide association studies (GWAS) have also identified 76 susceptibility loci associated with prostate cancer risk, which occur commonly but are of low penetrance. However, these mutations interact multiplicatively, which can result in substantially increased risk. Currently, approximately 30% of the familial risk is due to such variants. Evaluating the functional aspects of these variants would contribute to our understanding of prostate cancer aetiology and would enable population risk stratification for screening. Furthermore, understanding the genetic risks of prostate cancer might inform predictions of treatment responses and toxicities, with the goal of personalized therapy. However, risk modelling and clinical translational research are needed before we can translate risk profiles generated from these variants into use in the clinical setting for targeted screening and treatment.

Germline genetic variants associated with prostate cancer and potential relevance to clinical practice

The inherited link of prostate cancer predisposition has been supported using data from early epidemiological studies, as well as from familial and twin studies. Early linkage analyses and candidate gene approaches to identify these variants yielded mixed results. Since then, multiple genetic variants associated with prostate cancer susceptibility have now been found from genome-wide association studies (GWAS). Their clinical utility, however, remains unknown. It is recognised that collaborative efforts are needed to ensure adequate sample sizes are available to definitively investigate the genetic-clinical interactions. These could have important implications for public health as well as individualised prostate cancer management strategies. With the costs of genotyping decreasing and direct-to-consumer testing already offered for these common variants, it is envisaged that a lot of attention will be focussed in this area. These results will enable more refined risk stratification which will be important for targeting screening and prevention to higher risk groups. Ascertaining their clinical role remains an important goal for the GWAS community with international consortia now established, pooling efforts and resources to move this field forward.

Human HOX gene disorders

The Hox genes are an evolutionarily conserved family of genes, which encode a class of important transcription factors that function in numerous developmental processes. Following their initial discovery, a substantial amount of information has been gained regarding the roles Hox genes play in various physiologic and pathologic processes. These processes range from a central role in anterior-posterior patterning of the developing embryo to roles in oncogenesis that are yet to be fully elucidated. In vertebrates there are a total of 39 Hox genes divided into 4 separate clusters. Of these, mutations in 10 Hox genes have been found to cause human disorders with significant variation in their inheritance patterns, penetrance, expressivity and mechanism of pathogenesis. This review aims to describe the various phenotypes caused by germline mutation in these 10 Hox genes that cause a human phenotype, with specific emphasis paid to the genotypic and phenotypic differences between allelic disorders. As clinical whole exome and genome sequencing is increasingly utilized in the future, we predict that additional Hox gene mutations will likely be identified to cause distinct human phenotypes. As the known human phenotypes closely resemble gene-specific murine models, we also review the homozygous loss-of-function mouse phenotypes for the 29 Hox genes without a known human disease. This review will aid clinicians in identifying and caring for patients affected with a known Hox gene disorder and help recognize the potential for novel mutations in patients with phenotypes informed by mouse knockout studies.

Prevalence of the HOXB13 G84E mutation among unaffected men with a family history of prostate cancer

HOXB13 (G84E) was reported to significantly increase risk for prostate cancer. The goal of the current analysis was to assess the prevalence of G84E in ethnically-diverse high-risk men undergoing prostate cancer screening and place the carrier frequency within the context of prevalence estimates from reported studies to gain insight into the future role of this mutation in genetic counseling. PRAP is a prostate cancer screening program for unaffected men ages 35-69 with a family history of prostate cancer or African descent. HOXB13 G84E was genotyped by pyrosequencing in 649 PRAP participants with available DNA. Prevalence of the mutation was calculated for PRAP and for reported studies and exact binomial confidence intervals were generated. Prevalence of the G84E mutation in non-African PRAP men was 0.73 %. When placed in context of the literature, this was higher than reported controls. One G84E mutation carrier was notably of Hispanic background. While the HOXB13 G84E mutation may be rare, there may be a future role in genetic testing for this mutation after further studies of clinical utility in assessing prostate cancer risk.

Two-gene expression ratio as predictor for breast cancer treated with tamoxifen: evidence from meta-analysis

A HOXB13-to-IL17BR expression ratio was previously identified to predict a clinical outcome of breast cancer patients treated with adjuvant tamoxifen. A large number of studies were addressed to confirm its function as a predictor of breast cancer outcome treated with tamoxifen. However, conflicting results were got. In this study, a systematic search of databases was carried out, and other relevant papers were also identified. Then, the analyses were conducted according to the PRISMA and MOOSE guidelines. After full review, 11 studies with a total of 2,958 participants were deemed eligible and were included in the study. Pooled results revealed that women with higher HOXB13-to-IL17BR expression ratio had significantly worse outcomes in breast patients treated with tamoxifen, especially for those who are negative of node.

Knockdown of the gene for homeobox protein HOXB13 reduces toxicity of oxidative-stress inducers in HEK293 cells

HEK293 cells transfected with a double-stranded siRNA to suppress expression of the homeobox gene HOXB13 were highly resistant to oxidative stress-inducing agents, such as hydrogen peroxide, N-ethylmaleimide (NEM), and paraquat. This finding suggests that HOXB13 might enhance cell injury caused by oxidative stress.

Evaluation of reported prostate cancer risk-associated SNPs from genome-wide association studies of various racial populations in Chinese men

BACKGROUND

Several genome-wide association studies (GWAS) of prostate cancer (PCa) have identified many single nucleotide polymorphisms (SNPs) that are significantly associated with PCa risk in various racial groups. The objective of this study is to evaluate which of these SNPs are associated with PCa risk in Chinese men and estimate their strength of association.

METHODS

All SNPs that were reported to be associated with PCa risk in GWAS from populations of European, African American, Japanese, and Chinese descent were evaluated in 1,922 PCa cases and 2,175 controls selected from the Chinese Consortium for Prostate Cancer Genetics (ChinaPCa). A logistic regression analysis was used to estimate allelic odds ratios (ORs) of these SNPs for PCa.

RESULTS

Among the 53 SNPs, 50 were polymorphic in the Chinese population. Of which, 10 and 24 SNPs were significantly associated with PCa risk in Chinese men at P < 0.001 and <0.05, respectively. These 24 significant SNPs included 17, 5, and 2 SNPs that were originally discovered in European, Japanese, and Chinese descent, respectively. The estimated ORs ranged from 1.10 to 1.49 and the direction of association was consistent with previous studies. When ORs were estimated separately for PCa with Gleason score ≤7 and ≥8, a marginally significant difference in ORs was found only for two of the 24 SNPs (P = 0.02 and 0.04).

CONCLUSION

About half of PCa risk-associated SNPs identified in GWAS of various populations are associated with PCa risk in Chinese men. Information on PCa risk-associated SNPs and their ORs may facilitate risk assessment of PCa risk in Chinese men.

Developmental disease and cancer: biological and clinical overlaps

Numerous parallelisms exist between development and cancer. In this article, I review some of the founding ideas linking development and cancer, and highlight clinical conditions exhibiting features of both developmental derangement and cancer predisposition, including cohesinopathies, rasopathies, phakomatoses, Proteus syndrome and other overgrowth disorders, recessive chromosome breakage syndromes, and dominant hereditary cancer syndromes. I suggest that these disorders encompass a continuous spectrum spanning clinical genetics and clinical oncology, and derive some general implications that might be useful in the future for the treatment of these diseases.

A common nonsense mutation of the BLM gene and prostate cancer risk and survival

BACKGROUND

Germline mutations of BRCA2 and NBS1 genes cause inherited recessive chromosomal instability syndromes and predispose to prostate cancer of poor prognosis. Mutations of the BLM gene cause another chromosomal instability clinical syndrome, called Bloom syndrome. Recently, a recurrent truncating mutation of BLM (Q548X) has been associated with a 6-fold increased risk of breast cancer in Russia, Belarus and Ukraine, but its role in prostate cancer etiology and survival has not been investigated yet.

METHODS

To establish whether the Q548X allele of the BLM gene is present in Poland, and whether this allele predisposes to poor prognosis prostate cancer, we genotyped 3337 men with prostate cancer and 2604 controls.

RESULTS

Q548X was detected in 13 of 3337 (0.4%) men with prostate cancer compared to 15 of 2604 (0.6%) controls (OR=0.7; 95% CI 0.3-1.4). A positive family history of any cancer in a first- or second-degree relative was seen only in 4 of the 13 (30%) mutation positive families, compared to 49% (1485/3001) of the non-carrier families (p=0.3). The mean follow-up was 49months. Survival was similar among carriers of Q548X and non-carriers (HR=1.1; p=0.9). The 5-year survival for men with a BLM mutation was 83%, compared to 72% for mutation-negative cases.

CONCLUSIONS

BLM Q548X is a common founder mutation in Poland. We found no evidence that this mutation predisposes one to prostate cancer or affect prostate cancer survival. However, based on the observed 0.6% population frequency of the Q548X allele, we estimate that one in 100,000 children should be affected by Bloom syndrome in Poland.

Tumor suppressor p16INK4A is necessary for survival of cervical carcinoma cell lines

The tumor suppressor p16(INK4A) inhibits formation of enzymatically active complexes of cyclin-dependent kinases 4 and 6 (CDK4/6) with D-type cyclins. Oncogenic stress induces p16(INK4A) expression, which in turn triggers cellular senescence through activation of the retinoblastoma tumor suppressor. Subversion of oncogene-induced senescence is a key step during cancer development, and many tumors have lost p16(INK4A) activity by mutation or epigenetic silencing. Human papillomavirus (HPV)-associated tumors express high levels of p16(INK4A) in response to E7 oncoprotein expression. Induction of p16(INK4A) expression is not a consequence of retinoblastoma tumor suppressor inactivation but is triggered by a cellular senescence response and is mediated by epigenetic derepression through the H3K27-specific demethylase (KDM)6B. HPV E7 expression causes an acute dependence on KDM6B expression for cell survival. The p16(INK4A) tumor suppressor is a critical KDM6B downstream transcriptional target and its expression is critical for cell survival. This oncogenic p16(INK4A) activity depends on inhibition of CDK4/CDK6, suggesting that in cervical cancer cells where retinoblastoma tumor suppressor is inactivated, CDK4/CDK6 activity needs to be inhibited in order for cells to survive. Finally, we note that HPV E7 expression creates a unique cellular vulnerability to small-molecule KDM6A/B inhibitors.

G84E mutation in HOXB13 is firmly associated with prostate cancer risk: a meta-analysis

The rare but recurrent germline G84E mutation in HOXB13 was recently found to be associated with a significantly increased risk of familial prostate cancer (PCa). However, epidemiologic findings have been inconsistent. In an attempt to confirm and expand the findings that the PCa risk increased in men carrying G84E, we therefore performed a meta-analysis to clarify the association between the germline G84E mutation and PCa risk. We also aim to verify the increased PCa risk with respect to diagnostic age, family history, and disease aggressiveness. Comprehensive search of databases was carried out, and other relevant articles were also identified. Then, the meta-analyses were conducted according to the standard guidelines. A total of 11 studies with 120,167 participants were included on the basis of inclusion criteria. The G84E allele carrier frequencies ranged from 0.1 to 4.9 % in the patients with PCa, as compared with 0 to 1.4 % in control subjects. Men with the HOXB13 G84E variant had a 4.51-fold higher relative risk of PCa compared with non-carriers (95 % CI 3.28-6.20). The much higher risks were observed in individuals with early onset (odds ratio (OR) = 9.73, 95 % confidence interval (CI) 6.57-14.39), more than two affected relatives (OR = 7.27, 95 % CI 4.02-13.15), and highly aggressive disease (OR = 5.81, 95 % CI 3.72-9.08). Our findings provide further evidences that the rare mutation in HOXB13 contributes to both hereditary and sporadic PCa risk. Despite the low G84E carrier rate, biological and clinical implications of the mutation in subjects with early onset, more than two affected relatives, and highly aggressive disease remain important in continued investigation.

Germline missense variants in the BTNL2 gene are associated with prostate cancer susceptibility

BACKGROUND

Rare, inherited mutations account for 5% to 10% of all prostate cancer cases. However, to date, few causative mutations have been identified.

METHODS

To identify rare mutations for prostate cancer, we conducted whole-exome sequencing (WES) in multiple kindreds (n = 91) from 19 hereditary prostate cancer (HPC) families characterized by aggressive or early-onset phenotypes. Candidate variants (n = 130) identified through family- and bioinformatics-based filtering of WES data were then genotyped in an independent set of 270 HPC families (n = 819 prostate cancer cases; n = 496 unaffected relatives) for replication. Two variants with supportive evidence were subsequently genotyped in a population-based case-control study (n = 1,155 incident prostate cancer cases; n = 1,060 age-matched controls) for further confirmation. All participants were men of European ancestry.

RESULTS

The strongest evidence was for two germline missense variants in the butyrophilin-like 2 (BTNL2) gene (rs41441651, p.Asp336Asn and rs28362675, p.Gly454Cys) that segregated with affection status in two of the WES families. In the independent set of 270 HPC families, 1.5% (rs41441651; P = 0.0032) and 1.2% (rs28362675; P = 0.0070) of affected men, but no unaffected men, carried a variant. Both variants were associated with elevated prostate cancer risk in the population-based study (rs41441651: OR, 2.7; 95% CI, 1.27-5.87; P = 0.010; rs28362675: OR, 2.5; 95% CI, 1.16-5.46; P = 0.019).

CONCLUSIONS

Results indicate that rare BTNL2 variants play a role in susceptibility to both familial and sporadic prostate cancer.

IMPACT

Results implicate BTNL2 as a novel prostate cancer susceptibility gene.

Introduction to deep sequencing and its application to drug addiction research with a focus on rare variants

Through linkage analysis, candidate gene approach, and genome-wide association studies (GWAS), many genetic susceptibility factors for substance dependence have been discovered such as the alcohol dehydrogenase gene (ALDH2) for alcohol dependence (AD) and nicotinic acetylcholine receptor (nAChR) subunit variants on chromosomes 8 and 15 for nicotine dependence (ND). However, these confirmed genetic factors contribute only a small portion of the heritability responsible for each addiction. Among many potential factors, rare variants in those identified and unidentified susceptibility genes are supposed to contribute greatly to the missing heritability. Several studies focusing on rare variants have been conducted by taking advantage of next-generation sequencing technologies, which revealed that some rare variants of nAChR subunits are associated with ND in both genetic and functional studies. However, these studies investigated variants for only a small number of genes and need to be expanded to broad regions/genes in a larger population. This review presents an update on recently developed methods for rare-variant identification and association analysis and on studies focused on rare-variant discovery and function related to addictions.

A population-based analysis of clustering identifies a strong genetic contribution to lethal prostate cancer

BACKGROUND

Prostate cancer is a common and often deadly cancer. Decades of study have yet to identify genes that explain much familial prostate cancer. Traditional linkage analysis of pedigrees has yielded results that are rarely validated. We hypothesize that there are rare segregating variants responsible for high-risk prostate cancer pedigrees, but recognize that within-pedigree heterogeneity is responsible for significant noise that overwhelms signal. Here we introduce a method to identify homogeneous subsets of prostate cancer, based on cancer characteristics, which show the best evidence for an inherited contribution.

METHODS

We have modified an existing method, the Genealogical Index of Familiality (GIF) used to show evidence for significant familial clustering. The modification allows a test for excess familial clustering of a subset of prostate cancer cases when compared to all prostate cancer cases.

RESULTS

Consideration of the familial clustering of eight clinical subsets of prostate cancer cases compared to the expected familial clustering of all prostate cancer cases identified three subsets of prostate cancer cases with evidence for familial clustering significantly in excess of expected. These subsets include prostate cancer cases diagnosed before age 50 years, prostate cancer cases with body mass index (BMI) greater than or equal to 30, and prostate cancer cases for whom prostate cancer contributed to death.

CONCLUSIONS

This analysis identified several subsets of prostate cancer cases that cluster significantly more than expected when compared to all prostate cancer familial clustering. A focus on high-risk prostate cancer cases or pedigrees with these characteristics will reduce noise and could allow identification of the rare predisposition genes or variants responsible.

Importance of HOX genes in normal prostate gland formation, prostate cancer development and its early detection

The aims of this paper were to review the published literature on the role of HOX genes in the development of the normal prostate gland and in prostate cancer and to discuss the potential role of the HOX family member, Engrailed-2 (EN2), as a diagnostic test of PCa. Hox genes were first described in the fruit fly Drosphila melanogaster, where they specify the body plan and control the formation of body segments. They belong to a family of homeodomain-containing transcription factors that determine cell and tissue identity during normal embryonic development. They have been shown to be re-expressed by several different types of cancers. Studies have shown that different Hox genes are responsible for the development of the separate lobes of the prostate gland, the seminal vesicles and the epididymis. All HOX13 paralogues are expressed in the adult human prostate, suggesting the possibility of similarities between the function and expression of HOX genes within urological structures at similar anterior-posterior positions. The oncogenic and tumour suppressor signalling pathways associated with PCa converge on the HOX gene network, which ultimately controls gene expression, affecting tumour formation and metastatic progression. The Engrailed genes (EN1 and EN2) from the HOX gene family show a very high degree of functional conservation during embryonic development. Urinary EN2 is being investigated as a potential diagnostic marker of early PCa. It is secreted into the urine by PCa cells but not by normal prostatic tissue. A recent study has shown an association between urinary EN2 levels and cancer volume in radical prostatectomy specimens. The ability to predict tumour volume could inform the treatment decision-making process for patients with localized PCa choosing between active surveillance and radical treatment options.

Androgens and prostate cancer; pathogenesis and deprivation therapy

Although androgen receptor signaling is critical for prostate cancer growth and survival, evidence supporting a favorable risk-benefit ratio of androgen deprivation therapy (ADT) is currently limited to men with high-risk or metastatic disease. This is in part because ADT has been associated with a number of constitutional and somatic side effects, consistent with the widespread tissue expression of sex steroid receptors. ADT is the most common contemporary cause of severe hypogonadism, and men receiving this therapy represent a unique model of severe sex steroid deficiency with a defined time of onset. This review will present an update on the role of ADT in the treatment of prostate cancer, will summarize recent evidence regarding ADT-associated adverse effects with particular emphasis on cardiometabolic and musculoskeletal health, and will provide recommendations for further research.

Prostate cancer genomics by high-throughput technologies: genome-wide association study and sequencing analysis

Prostate cancer (PC) is the most common malignancy in males. It is evident that genetic factors at both germline and somatic levels play critical roles in prostate carcinogenesis. Recently, genome-wide association studies (GWAS) by high-throughput genotyping technology have identified more than 70 germline variants of various genes or chromosome loci that are significantly associated with PC susceptibility. They include multiple 8q24 loci, prostate-specific genes, and metabolism-related genes. Somatic alterations in PC genomes have been explored by high-throughput sequencing technologies such as whole-genome sequencing and RNA sequencing, which have identified a variety of androgen-responsive events and fusion transcripts represented by E26 transformation-specific (ETS) gene fusions. Recent innovations in high-throughput genomic technologies have enabled us to analyze PC genomics more comprehensively, more precisely, and on a larger scale in multiple ethnic groups to increase our understanding of PC genomics and biology in germline and somatic studies, which can ultimately lead to personalized medicine for PC diagnosis, prevention, and therapy. However, these data indicate that the PC genome is more complex and heterogeneous than we expected from GWAS and sequencing analyses.

Analytic and clinical validation of a prostate cancer-enhanced messenger RNA detection assay in whole blood as a prognostic biomarker for survival

BACKGROUND

Biomarkers based on detecting prostate cancer (PCa)-specific transcripts in blood are associated with inferior outcomes, but their validation in a clinical context is lacking.

OBJECTIVE

To determine whether detecting enhanced transcripts for PCa in whole blood using an analytically valid assay has prognostic significance relative to circulating tumor cell (CTC) enumeration.

DESIGN, SETTING, AND PARTICIPANTS

The detection of KLK3, KLK2, HOXB13, GRHL2, and FOXA1 in whole blood by reverse transcription polymerase chain reaction (RT-PCR) was studied in 97 men with metastatic castration-resistant PCa (mCRPC) as a prognostic factor for overall survival.

INTERVENTION

The 2.5 ml of blood was collected in PAXgene tubes for total RNA extraction and 7.5 ml for CTC enumeration from patients with progressive mCRPC.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

PCa-enriched genes were detected using a sensitive RT-PCR assay in whole blood from patients with mCRPC. Analytical validity of the assay was established in a clinical laboratory environment. The frequency of detecting transcripts was compared to CTC enumeration using CellSearch in an independent data set and survival associations were explored by concordance probability estimate (CPE).

RESULTS AND LIMITATIONS

Two or more genes were detected by PCR in 53% of patients (51 of 97; 95% confidence interval [CI], 43-63%), and unfavorable CTC counts (five of more cells) were seen in 46% (45 of 97; 95% CI, 36-56%). Importantly, transcripts were detectable in 11 of 52 patients with favorable CTC counts (21%; 95% CI, 8-35%). Transcript detection predicted overall survival in a proportional hazards model. Significantly, the predictive accuracy of RT-PCR detection in combination with CTC enumeration had a CPE of 0.752 (standard error: 0.038), although this was limited by the number of patients evaluated.

CONCLUSIONS

This validated RT-PCR assay detecting prostate-specific RNA in whole blood is prognostic for survival and may assess patient risk in tandem with CellSearch CTC enumeration. Its clinical utility is being prospectively explored.

The molecular basis for ethnic variation and histological subtype differences in prostate cancer

Prostate cancer is a common malignancy among men in Western countries. Recently the morbidity and mortality of prostate cancer increase dramatically in several oriental countries including China. Rapidly evolving technology in molecular biology such as high-throughput sequencing and integrative analysis of genomic and transcriptomic landscapes have enabled the identification of key oncogenic events for prostate cancer initiation, progression and resistance to hormonal therapy. These surging data of prostate cancer genome also provide insights on ethnic variation and the differences in histological subtype of this disease. In this review, differences in the incidence of prostate cancer and the prevalence of main genetic alterations between Asian and Western populations are discussed. We also review the recent findings on the mechanisms underlying neuroendocrine differentiation of prostate cancer and the development of small cell neuroendocrine carcinoma after androgen deprivation therapy.

Early detection of prostate cancer: European Association of Urology recommendation

BACKGROUND

The recommendations and the updated EAU guidelines consider early detection of PCa with the purpose of reducing PCa-related mortality and the development of advanced or metastatic disease.

OBJECTIVE

This paper presents the recommendations of the European Association of Urology (EAU) for early detection of prostate cancer (PCa) in men without evidence of PCa-related symptoms.

EVIDENCE ACQUISITION

The working panel conducted a systematic literature review and meta-analysis of prospective and retrospective clinical studies on baseline prostate-specific antigen (PSA) and early detection of PCa and on PCa screening published between 1990 and 2013 using Cochrane Reviews, Embase, and Medline search strategies.

EVIDENCE SYNTHESIS

The level of evidence and grade of recommendation were analysed according to the principles of evidence-based medicine. The current strategy of the EAU recommends that (1) early detection of PCa reduces PCa-related mortality; (2) early detection of PCa reduces the risk of being diagnosed and developing advanced and metastatic PCa; (3) a baseline serum PSA level should be obtained at 40-45 yr of age; (4) intervals for early detection of PCa should be adapted to the baseline PSA serum concentration; (5) early detection should be offered to men with a life expectancy ≥ 10 yr; and (6) in the future, multivariable clinical risk-prediction tools need to be integrated into the decision-making process.

CONCLUSIONS

A baseline serum PSA should be offered to all men 40-45 yr of age to initiate a risk-adapted follow-up approach with the purpose of reducing PCa mortality and the incidence of advanced and metastatic PCa. In the future, the development and application of multivariable risk-prediction tools will be necessary to prevent over diagnosis and over treatment.

Five linkage regions each harbor multiple type 2 diabetes genes in the African American subset of the GENNID Study

We previously localized type 2 diabetes (T2D)-susceptibility genes to five chromosomal regions through a genome-wide linkage scan of T2D and age of diagnosis (AOD) in the African American subset of the GENNID sample. To follow up these findings, we repeated the linkage and association analysis using genotypes on an additional 9203 fine-mapping single nucleotide polymorphisms (SNPs) selected to tag genes under the linkage peaks. In each of the five regions, we confirmed linkage and inferred the presence of ≥2 susceptibility genes. The evidence of multiple susceptibility genes consisted of: (1) multiple linkage peaks in four of the five regions; and (2) association of T2D and AOD with SNPs within ≥2 genes in every region. The associated genes included 3 previously reported to associate with T2D or related traits (GRB10, NEDD4L, LIPG) and 24 novel candidate genes, including genes in lipid metabolism (ACOXL) and cell-cell and cell-matrix adhesion (MAGI2, CLDN4, CTNNA2).

Common genetic variants associated with disease from genome-wide association studies are mutually exclusive in prostate cancer and rheumatoid arthritis

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The link between inflammation and cancer has long been reported and inflammation is thought to play a role in the pathogenesis of many cancers, including prostate cancer (PrCa). Over the last 5 years, genome-wide association studies (GWAS) have reported numerous susceptibility loci that predispose individuals to many different traits. The present study aims to ascertain if there are common genetic risk profiles that might predispose individuals to both PrCa and the autoimmune inflammatory condition, rheumatoid arthritis. These results could have potential public heath impact in terms of screening and chemoprevention.

OBJECTIVES

To investigate if potential common pathways exist for the pathogenesis of autoimmune disease and prostate cancer (PrCa). To ascertain if the single nucleotide polymorphisms (SNPs) reported by genome-wide association studies (GWAS) as being associated with susceptibility to PrCa are also associated with susceptibility to the autoimmune disease rheumatoid arthritis (RA).

MATERIALS AND METHODS

The original Wellcome Trust Case Control Consortium (WTCCC) UK RA GWAS study was expanded to include a total of 3221 cases and 5272 controls. In all, 37 germline autosomal SNPs at genome-wide significance associated with PrCa risk were identified from a UK/Australian PrCa GWAS. Allele frequencies were compared for these 37 SNPs between RA cases and controls using a chi-squared trend test and corrected for multiple testing (Bonferroni).

RESULTS

In all, 33 SNPs were able to be analysed in the RA dataset. Proxies could not be located for the SNPs in 3q26, 5p15 and for two SNPs in 17q12. After applying a Bonferroni correction for the number of SNPs tested, the SNP mapping to CCHCR1 (rs130067) retained statistically significant evidence for association (P = 6 × 10(-4) ; odds ratio [OR] = 1.15, 95% CI: 1.06-1.24); this has also been associated with psoriasis. However, further analyses showed that the association of this allele was due to confounding by RA-associated HLA-DRB1 alleles.

CONCLUSIONS

There is currently no evidence that SNPs associated with PrCa at genome-wide significance are associated with the development of RA. Studies like this are important in determining if common genetic risk profiles might predispose individuals to many diseases, which could have implications for public health in terms of screening and chemoprevention.

Modeling prostate cancer in mice: something old, something new, something premalignant, something metastatic

More than 15 years ago, the first generation of genetically engineered mouse (GEM) models of prostate cancer was introduced. These transgenic models utilized prostate-specific promoters to express SV40 oncogenes specifically in prostate epithelium. Since the description of these initial models, there have been a plethora of GEM models of prostate cancer representing various perturbations of oncogenes or tumor suppressors, either alone or in combination. This review describes these GEM models, focusing on their relevance for human prostate cancer and highlighting their strengths and limitations, as well as opportunities for the future.

A personalised approach to prostate cancer screening based on genotyping of risk founder alleles

Background:

To evaluate whether genotyping for 18 prostate cancer founder variants is helpful in identifying high-risk individuals and for determining optimal screening regimens.

Methods:

A serum PSA level was measured and a digital rectal examination (DRE) was performed on 2907 unaffected men aged 40–90. Three hundred and twenty-three men with an elevated PSA (⩾4 ng ml⁻¹) or an abnormal DRE underwent a prostate biopsy. All men were genotyped for three founder alleles in BRCA1 (5382insC, 4153delA and C61G), for four alleles in CHEK2 (1100delC, IVS2+1G>A, del5395 and I157T), for one allele in NBS1 (657del5), for one allele in HOXB13 (G84E), and for nine low-risk single-nucleotide polymorphisms (SNPs).

Results:

On the basis of an elevated PSA or an abnormal DRE, prostate cancer was diagnosed in 135 of 2907 men (4.6%). In men with a CHEK2 missense mutation I157T, the cancer detection rate among men with an elevated PSA or an abnormal DRE was much higher (10.2%, P=0.0008). The cancer detection rate rose with the number of SNP risk genotypes observed from 1.2% for men with no variant to 8.6% for men who carried six or more variants (P=0.04). No single variant was helpful on its own in predicting the presence of prostate cancer, however, the combination of all rare mutations and SNPs improved predictive power (area under the curve=0.59; P=0.03).

Conclusion:

These results suggest that testing for germline CHEK2 mutations improves the ability to predict the presence of prostate cancer in screened men, however, the clinical utility of incorporating DNA variants in the screening process is marginal.

Biochemical and functional interactions of human papillomavirus proteins with polycomb group proteins

The role of enzymes involved in polycomb repression of gene transcription has been studied extensively in human cancer. Polycomb repressive complexes mediate oncogene-induced senescence, a principal innate cell-intrinsic tumor suppressor pathway that thwarts expansion of cells that have suffered oncogenic hits. Infections with human cancer viruses including human papillomaviruses (HPVs) and Epstein-Barr virus can trigger oncogene-induced senescence, and the viruses have evolved strategies to abrogate this response in order to establish an infection and reprogram their host cells to establish a long-term persistent infection. As a consequence of inhibiting polycomb repression and evading oncogene induced-senescence, HPV infected cells have an altered epigenetic program as evidenced by aberrant homeobox gene expression. Similar alterations are frequently observed in non-virus associated human cancers and may be harnessed for diagnosis and therapy.

Elevated risk of prostate cancer among men with Lynch syndrome

PURPOSE

Prostate cancer has been described as a component tumor of Lynch syndrome (LS), with tumors obtained from mutation carriers demonstrating the DNA mismatch repair deficiency phenotype. Previous studies quantifying prostate cancer risk in LS have provided conflicting results.

METHODS

We examined cancer histories of probands and their first- through fourth-degree relatives for 198 independent mutation-positive LS families enrolled in two US familial cancer registries. Modified segregation analysis was used to calculate age-specific cumulative risk or penetrance estimates, with accompanying Wald-type CIs. Cumulative lifetime risks and hazard ratio (HR) estimates for prostate cancer were calculated and compared with those of the general population.

RESULTS

Ninety-seven cases of prostate cancer were observed in 4,127 men. Median age at prostate cancer diagnosis was 65 years (range, 38 to 89 years), with 11.53% of affected individuals diagnosed before age 50 years. The cumulative risk of prostate cancer at ages 60 and 80 years was 6.30% (95% CI, 2.47 to 9.96) and 30.0% (95% CI, 16.54 to 41.30), as compared with the population risk of 2.59% and 17.84%, respectively. The overall prostate cancer HR among carriers was 1.99 (95% CI, 1.31 to 3.03).

CONCLUSION

The cumulative lifetime risk of prostate cancer in individuals with LS is two-fold higher than in the general population and is slightly higher in carriers diagnosed before age 60 years (HR, 2.48; 95% CI, 1.34 to 4.59). These estimates are clinically valuable to quantify risk for both patients and providers.

Prostate cancer risk-associated genetic markers and their potential clinical utility

Prostate cancer (PCa) is one of the most common cancers among men in Western developed countries and its incidence has increased considerably in many other parts of the world, including China. The etiology of PCa is largely unknown but is thought to be multifactorial, where inherited genetics plays an important role. In this article, we first briefly review results from studies of familial aggregation and genetic susceptibility to PCa. We then recap key findings of rare and high-penetrance PCa susceptibility genes from linkage studies in PCa families. We devote a significant portion of this article to summarizing discoveries of common and low-penetrance PCa risk-associated single-nucleotide polymorphisms (SNPs) from genetic association studies in PCa cases and controls, especially those from genome-wide association studies (GWASs). A strong focus of this article is to review the literature on the potential clinical utility of these implicated genetic markers. Most of these published studies described PCa risk estimation using a genetic score derived from multiple risk-associated SNPs and its utility in determining the need for prostate biopsy. Finally, we comment on the newly proposed concept of genetic score; the notion is to treat it as a marker for genetic predisposition, similar to family history, rather than a diagnostic marker to discriminate PCa patients from non-cancer patients. Available evidence to date suggests that genetic score is an objective and better measurement of inherited risk of PCa than family history. Another unique feature of this article is the inclusion of genetic association studies of PCa in Chinese and Japanese populations.

HOXB13 mutations in a population-based, case-control study of prostate cancer

BACKGROUND

Prostate cancer (PC) is the most frequently diagnosed non-skin malignancy in men in the Western world, yet few disease-associated mutations have been found. Recently, a low frequency recurring mutation in the HOXB13 gene was reported among both hereditary PC families and men from the general population.

MATERIALS AND METHODS

We determined the distribution and frequency of the G84E HOXB13 variant in 1,310 incipient PC cases and 1,259 age-mated controls from a population-based, case-control study of PC.

RESULTS

The G84E mutation was more frequent in cases than controls (1.3% vs. 0.4%, respectively), and men with the HOXB13 G84E variant had a 3.3-fold higher relative risk of PC compared with noncarriers (95% CI, 1.21-8.96). There was a stronger association between the G84E variant and PC among men with no first-degree relative with PC (OR, 4.04; 95% CI, 1.12-14.51) compared to men with a family history of PC (OR, 1.49; 95% CI, 0.30-7.50; P = 0.36 for interaction). We observed some evidence of higher risk estimates associated with the variant for men with higher versus lower Gleason score (OR, 4.13; 95% CI, 1.38-12.38 vs. OR, 2.71; 95% CI, 0.88-8.30), and advanced versus local stage (OR, 4.47; 95% CI, 1.28-15.57 vs. OR, 2.98; 95% CI, 1.04-8.49), however these differences were not statistically different.

CONCLUSIONS

These results confirm the association of a rare HOXB13 mutation with PC in the general population and suggest that this variant may be associated with features of more aggressive disease.

Identification of a novel NBN truncating mutation in a family with hereditary prostate cancer

Nibrin (NBN), located on chromosome 8q21 is a gene involved in DNA double-strand break repair that has been implicated in the rare autosomal recessive chromosomal instability syndrome known as Nijmegen Breakage Syndrome (NBS). NBS is characterized by specific physical characteristics (microcephaly and dysmorphic facies), immunodeficiency, and increased risk of malignancy. Individuals who are heterozygous for NBN mutations are clinically asymptomatic, but may display an elevated risk for certain cancers including, but not limited to, ovarian and prostate cancer as well as various lymphoid malignancies. In this study, 94 unrelated familial prostate cancer cases from the University of Michigan Prostate Cancer Genetics Project (n = 54) and Johns Hopkins University (n = 40) were subjected to targeted next-generation sequencing of the exons, including UTRs, of NBN. One individual of European descent, diagnosed with prostate cancer at age 52, was identified to have a heterozygous 2117 C > G mutation in exon 14 of the gene, that results in a premature stop at codon 706 (S706X). Sequencing of germline DNA from additional male relatives showed partial co-segregation of the NBN S706X mutation with prostate cancer. This NBN mutation was not observed among 2768 unrelated European men (1859 with prostate cancer and 909 controls). NBN is involved in double-strand break repair as a component of the MRE11 (meiotic recombination 11)/RAD50/NBN genomic stability complex. The S706X mutation truncates the protein in a highly conserved region of NBN near the MRE11 binding site, thus suggesting a role for rare NBN mutations in prostate cancer susceptibility.

Strategy for detection of prostate cancer based on relation between prostate specific antigen at age 40-55 and long term risk of metastasis: case-control study

OBJECTIVE

To determine the association between concentration of prostate specific antigen (PSA) at age 40-55 and subsequent risk of prostate cancer metastasis and mortality in an unscreened population to evaluate when to start screening for prostate cancer and whether rescreening could be risk stratified.

DESIGN

Case-control study with 1:3 matching nested within a highly representative population based cohort study.

SETTING

Malmö Preventive Project, Sweden.

PARTICIPANTS

21,277 Swedish men aged 27-52 (74% of the eligible population) who provided blood at baseline in 1974-84, and 4922 men invited to provide a second sample six years later. Rates of PSA testing remained extremely low during median follow-up of 27 years.

MAIN OUTCOME MEASURES

Metastasis or death from prostate cancer ascertained by review of case notes.

RESULTS

Risk of death from prostate cancer was associated with baseline PSA: 44% (95% confidence interval 34% to 53%) of deaths occurred in men with a PSA concentration in the highest 10th of the distribution of concentrations at age 45-49 (≥ 1.6 µg/L), with a similar proportion for the highest 10th at age 51-55 (≥ 2.4 µg/L: 44%, 32% to 56%). Although a 25-30 year risk of prostate cancer metastasis could not be ruled out by concentrations below the median at age 45-49 (0.68 µg/L) or 51-55 (0.85 µg/L), the 15 year risk remained low at 0.09% (0.03% to 0.23%) at age 45-49 and 0.28% (0.11% to 0.66%) at age 51-55, suggesting that longer intervals between screening would be appropriate in this group.

CONCLUSION

Measurement of PSA concentration in early midlife can identify a small group of men at increased risk of prostate cancer metastasis several decades later. Careful surveillance is warranted in these men. Given existing data on the risk of death by PSA concentration at age 60, these results suggest that three lifetime PSA tests (mid to late 40s, early 50s, and 60) are probably sufficient for at least half of men.

Genetics and genomics of prostate cancer

Prostate cancer (PCa) is one of the most common malignancies in the world with over 890 000 cases and over 258 000 deaths worldwide each year. Nearly all mortalities from PCa are due to metastatic disease, typically through tumors that evolve to be hormone-refractory or castrate-resistant. Despite intensive epidemiological study, there are few known environmental risk factors, and age and family history are the major determinants. However, there is extreme heterogeneity in PCa incidence worldwide, suggesting that major determining factors have not been described. Genome-wide association studies have been performed and a considerable number of significant, but low-risk loci have been identified. In addition, several groups have analyzed PCa by determination of genomic copy number, fusion gene generation and targeted resequencing of candidate genes, as well as exome and whole genome sequencing. These initial studies have examined both primary and metastatic tumors as well as murine xenografts and identified somatic alterations in TP53 and other potential driver genes, and the disturbance of androgen response and cell cycle pathways. It is hoped that continued characterization of risk factors as well as gene mutation and misregulation in tumors will aid in understanding, diagnosing and better treating PCa.

Identification of 23 new prostate cancer susceptibility loci using the iCOGS custom genotyping array

Prostate cancer is the most frequently diagnosed cancer in males in developed countries. To identify common prostate cancer susceptibility alleles, we genotyped 211,155 SNPs on a custom Illumina array (iCOGS) in blood DNA from 25,074 prostate cancer cases and 24,272 controls from the international PRACTICAL Consortium. Twenty-three new prostate cancer susceptibility loci were identified at genome-wide significance (P < 5 × 10(-8)). More than 70 prostate cancer susceptibility loci, explaining ∼30% of the familial risk for this disease, have now been identified. On the basis of combined risks conferred by the new and previously known risk loci, the top 1% of the risk distribution has a 4.7-fold higher risk than the average of the population being profiled. These results will facilitate population risk stratification for clinical studies.

The G84E mutation in the HOXB13 gene is associated with an increased risk of prostate cancer in Poland

BACKGROUND

The G84E mutation in the HOXB13 gene has been associated with a high lifetime risk of prostate cancer in North America (about 20-fold). The geographical and ethnic extent of this recurrent allele has not yet been determined.

METHODS

We assayed for the presence of the G84E mutation in 3,515 prostate cancer patients and 2,604 controls from Poland and estimated the odds ratio for prostate cancer associated with the allele.

RESULTS

The G84E mutation was detected in 3 of 2,604 (0.1%) individuals from the general population in Poland and in 20 of 3,515 (0.6%) men with prostate cancer (Odds ratio [OR] = 5.0; 95% CI: 1.5-16.7; P = 0.008). The allele was present in 4 of 416 (1.0%) men with familial prostate cancer (OR = 8.4, 95% CI: 1.9-37.7; P = 0.005).

CONCLUSIONS

The G84E mutation predisposes to prostate cancer in Poland, but accounts for only a small proportion of cases. We expect that the G84E founder mutation might be present in other Slavic populations.

Germline HOXB13 p.Gly84Glu mutation and risk of colorectal cancer

INTRODUCTION

The HOXB13 pGly84Glu mutation has recently been associated with an increased risk of prostate cancer but the association of other cancer sites with this allele has not been assessed. Data has suggested that HOXB13 expression levels are decreased in colorectal cancer (CRC) cell lines indicating this gene may be involved in colorectal tumourigenesis.

METHODS

To evaluate a potential association of this mutation with CRC, we genotyped the mutation in 2695 CRC cases and 4593 controls from population-based registries in Canada and Australia.

RESULTS

The HOXB13 pGly84Glu mutation was more common in CRC cases than controls (0.48% vs. 0.17%, P=0.02) indicating a significant association between the HOXB13 variant and CRC risk (OR=2.8; 95%CI: 1.2-6.8). This association was attenuated but remained significant with the inclusion of previously published and publicly available genotype data. Pedigree analysis of cases and controls revealed that 7/21 HOXB13 mutation carriers had a family history of prostate cancer.

DISCUSSION

This report is the first to suggest a risk of CRC associated with mutations in the HOXB13 gene. These findings require further validation but may be of importance in the screening and genetic counseling of families known to carry the HOXB13 pGly84Glu mutation.

Testing for the recurrent HOXB13 G84E germline mutation in men with clinical indications for prostate biopsy

PURPOSE

The G84E variant of HOXB13 was recently found to be associated with a significantly increased risk of prostate cancer in a case control study. We estimated the prevalence of this mutation in a clinical population of men at risk for prostate cancer who were scheduled to undergo prostate biopsy.

MATERIALS AND METHODS

We prospectively collected clinical information and DNA samples from men who underwent diagnostic prostate biopsy between June 2005 and October 2011. We genotyped samples for HOXB13 G84E using the MassARRAY® system. We determined the prevalence of the G84E variant in the overall cohort, among patients with a positive family history and among men age 55 years or younger.

RESULTS

A total of 1,175 subjects underwent biopsy, of whom 948 had a DNA sample for analysis. The G84E variant was detected in 4 patients (prevalence 0.42%, 95% CI 0.12-1.08), of whom 3 had prostate cancer on biopsy. None of 301 patients with a positive family history (prevalence 0.00%, 95% CI 0.00-1.22) and 1 of 226 patients age 55 years or younger tested positive (prevalence 0.44%, 95% CI 0.01-2.44).

CONCLUSIONS

The HOXB13 G84E variant is rare in this cohort, even among those with a positive family history. Our findings question the utility of testing for this variant among unselected men presenting for a diagnostic prostate biopsy.

Genome-wide testing of putative functional exonic variants in relationship with breast and prostate cancer risk in a multiethnic population

Rare variation in protein coding sequence is poorly captured by GWAS arrays and has been hypothesized to contribute to disease heritability. Using the Illumina HumanExome SNP array, we successfully genotyped 191,032 common and rare non-synonymous, splice site, or nonsense variants in a multiethnic sample of 2,984 breast cancer cases, 4,376 prostate cancer cases, and 7,545 controls. In breast cancer, the strongest associations included either SNPs in or gene burden scores for genes LDLRAD1, SLC19A1, FGFBP3, CASP5, MMAB, SLC16A6, and INS-IGF2. In prostate cancer, one of the most associated SNPs was in the gene GPRC6A (rs2274911, Pro91Ser, OR = 0.88, P = 1.3 × 10(-5)) near to a known risk locus for prostate cancer; other suggestive associations were noted in genes such as F13A1, ANXA4, MANSC1, and GP6. For both breast and prostate cancer, several of the most significant associations involving SNPs or gene burden scores (sum of minor alleles) were noted in genes previously reported to be associated with a cancer-related phenotype. However, only one of the associations (rs145889899 in LDLRAD1, p = 2.5 × 10(-7) only seen in African Americans) for overall breast or prostate cancer risk was statistically significant after correcting for multiple comparisons. In addition to breast and prostate cancer, other cancer-related traits were examined (body mass index, PSA level, and alcohol drinking) with a number of known and potentially novel associations described. In general, these findings do not support there being many protein coding variants of moderate to high risk for breast and prostate cancer with odds ratios over a range that is probably required for protein coding variation to play a truly outstanding role in risk heritability. Very large sample sizes will be required to better define the role of rare and less penetrant coding variation in prostate and breast cancer disease genetics.

Population-based estimate of prostate cancer risk for carriers of the HOXB13 missense mutation G84E

The HOXB13 missense mutation G84E (rs138213197) is associated with increased risk of prostate cancer, but the current estimate of increased risk has a wide confidence interval (width of 95% confidence interval (CI) >200-fold) so the point estimate of 20-fold increased risk could be misleading. Population-based family studies can be more informative for estimating risks for rare variants, therefore, we screened for mutations in an Australian population-based series of early-onset prostate cancer cases (probands). We found that 19 of 1,384 (1.4%) probands carried the missense mutation, and of these, six (32%) had a family history of prostate cancer. We tested the 22 relatives of carriers diagnosed from 1998 to 2008 for whom we had a DNA sample, and found seven more carriers and one obligate carrier. The age-specific incidence for carriers was estimated to be, on average, 16.4 (95% CI 2.5-107.2) times that for the population over the time frame when the relatives were at risk prior to baseline. We then estimated the age and birth year- specific cumulative risk of prostate cancer (penetrance) for carriers. For example, the penetrance for an unaffected male carrier born in 1950 was 19% (95% CI 5-46%) at age 60 years, 44% (95% CI 18-74%) at age 70 years and 60% (95% CI 30-85%) at age 80 years. Our study has provided a population-based estimate of the average risk of prostate cancer for HOXB13 missense mutation G84E carriers that can be used to guide clinical practice and research. This study has also shown that the majority of hereditary prostate cancers due to the HOXB13 missense mutation are 'sporadic' in the sense that unselected cases with the missense mutation do not typically report having a family history of prostate cancer.

HOXB13 mutation and prostate cancer: studies of siblings and aggressive disease

BACKGROUND

Recent work detected for the first time a high-risk prostate cancer mutation, in homeobox B13 (HOXB13) among European-Americans.

METHODS

We further evaluated this G84E missense mutation (rs138213197) in two genetic association studies of prostate cancer: a family-based study of brothers and a case-control study of more aggressive disease (N = 2,665 total). We then calculated overall impact of this mutation by pooling all published studies of European-Americans.

RESULTS

In our studies, the mutation was found exclusively among men with prostate cancer (carrier frequency = 1.48%) or unaffected brothers of cases carrying the mutation (frequency = 0.34%), and carrying the mutation gave an OR for disease = 4.79 (P = 0.01). The G84E mutation was more common among men with an earlier age of onset (≤55 years) or a family history of prostate cancer. We also observed for the first time an African-American case carrying the G84E mutation, although at HOXB13 both of his chromosomes were of European-American ancestry. The pooled analysis also indicated that carrying the G84E mutation results in an almost five-fold increase in risk of prostate cancer (P = 3.5 × 10(-17)), and this risk is even higher among cases with an early age of prostate cancer onset (≤55 years) or a family history of disease: a test of heterogeneity across these strata gives P < 1 × 10(-5).

CONCLUSIONS

The HOXB13 mutation substantially increases risk of early onset, familial prostate cancer in European-American men.

IMPACT

Testing for the G84E mutation in men with a positive family history may help distinguish those who merit more regular screening for prostate cancer.

The G84E mutation of HOXB13 is associated with increased risk for prostate cancer: results from the REDUCE trial

A novel rare mutation, homeobox B13 (HOXB13) G84E, was reported to co-segregate with prostate cancer (PCa) in hereditary PCa families and associate with PCa risk in unrelated cases and controls. In this study, we aim to compare the G84E mutation frequency among subjects of different races/ethnicities from various geographic regions in the world and to assess its risk for developing PCa, in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial. All the 3508 subjects had initial negative prostate biopsy and were biopsied at Year 2 and 4 for detection of PCa. The G84E mutation was detected only in Caucasians, with the highest carrier frequency in Northern Europe (1.06%), followed by Western Europe (0.60%) and North America (0.31%). No mutation carrier was observed in Southern Europe, Eastern Europe, Latin America, Australia and South Africa. In Caucasians, the G84E mutation frequency was 0.99% and 0.24% in positive and negative biopsy subjects, respectively (P = 0.01). In positive biopsy subjects, the frequency was significantly higher in subjects with a positive family history than those without (4.31% versus 0.34%, P = 0.002). In the 4 year follow-up, the PCa detection rate was 53.8% among the 13 mutation carriers and 22.0% among 3186 non-carriers, relative risk = 2.45 (95% confidence interval: 1.48-4.07). All mutation carriers shared a common haplotype, suggesting a founder effect. In Finland, the G84E mutation was estimated to occur in the year 1792 (95% credible interval: 1735-1831). In conclusion, the G84E mutation of HOXB13, a relatively recent mutation that likely occurred in Northern Europe, significantly increases risk for PCa.