Prevalence of the HOXB13 G84E prostate cancer risk allele in men treated with radical prostatectomy

Clinical Significance of Gene Mutations and Polymorphic Variants and their Association with Prostate Cancer Risk in Polish Men

Objectives: We tested the association of germline variants in BRCA1, BRCA2, CHEK2, CDKN2A, CYP1B1, HOXB13, MLH1, NBS1, NOD2 andPALB2 genes, as well as in 8q24 region, with prostate cancer (PC) risk and estimated their impact on disease clinical course, including overall survival time in Polish men with localized PC qualified for radical treatment.Materials and Methods: DNA of 110 patients with localized prostate cancer treated with radical prostatectomy (RP), from each age group and with different stages of the disease. DNA samples of the control group consisted of 111 men, volunteers, without PC (age-matched to study group). Sanger sequencing, AS-PCR, RFLP-PCR, and multiplex-PCR were used for  variants detection.Results: The percentage of men with ≥1 germline variant was higher in PC group (52.7%) than in healthy men (37.8%) (P = .03). The presence of ≥2 variants was associated with shorter survival than the presence of one or no variant in the PC group (P = .14, trend). The HOXB13 G84E was detected in 2.9% of PC men and in no healthy men (P = .19, trend, OR = 7.21). A CHEK2 truncating mutation (1100delC or IVS2+1G>A) was detected in 2/110 (1.8%) PC patients and in no healthy men (P = .29, OR=5.14). The NBS1 I171V was detected in 2/110 (1.8%) PC patients and in no men from the control group (OR=5.14, P = .29, NS).Conclusions: We conclude that the presence of more than 2 germline variants was probably associated with shorter survival of patients with localized prostate cancer qualified for radical treatment. The HOXB13 (G84E), CHEK2 (1100delC or IVS2+1G>A) truncating variants and NBS1 (I171V) are associated with PC and hereditary form of the disease. The HOXB13 (G84E) and NOD2 (3020insC) single variants are associated with shorter and CYP1B1 (48CC, 119GG) single genotypes with longer overall survival.

ACK1-AR and AR-HOXB13 signaling axes: epigenetic regulation of lethal prostate cancers

The androgen receptor (AR) is a critical transcription factor in prostate cancer (PC) pathogenesis. Its activity in malignant cells is dependent on interactions with a diverse set of co-regulators. These interactions fluctuate depending on androgen availability. For example, the androgen depletion increases the dependence of castration-resistant PCs (CRPCs) on the ACK1 and HOXB13 cell survival pathways. Activated ACK1, an oncogenic tyrosine kinase, phosphorylates cytosolic and nuclear proteins, thereby avoiding the inhibitory growth consequences of androgen depletion. Notably, ACK1-mediated phosphorylation of histone H4, which leads to epigenetic upregulation of AR expression, has emerged as a critical mechanism of CRPC resistance to anti-androgens. This resistance can be targeted using the ACK1-selective small-molecule kinase inhibitor (R)- 9b. CRPCs also deploy the bromodomain and extra-terminal domain protein BRD4 to epigenetically increase HOXB13 gene expression, which in turn activates the MYC target genes AURKA/AURKB. HOXB13 also facilitates ligand-independent recruitment of the AR splice variant AR-V7 to chromatin, compensating for the loss of the chromatin remodeling protein, CHD1, and restricting expression of the mitosis control gene HSPB8. These studies highlight the crosstalk between AR-ACK1 and AR-HOXB13 pathways as key mediators of CRPC recurrence.

Risk of Prostate Cancer Associated With Familial and Hereditary Cancer Syndromes

PURPOSE

Recently developed clinical guidelines suggest that men in families with specific cancer syndromes, such as hereditary breast and ovarian cancer (HBOC), consider genetic testing, especially in the setting of aggressive disease. However, although a family history (FH) of the same disease among close relatives is an established risk factor for prostate cancer (PC), a direct comparison of PC risk for men with each syndrome in a single population is needed.

METHODS

The Utah Population Database was used to identify 619,630 men, age ≥ 40 years, who were members of a pedigree that included at least 3 consecutive generations. Each man was evaluated for FH of hereditary PC (HPC), HBOC, and Lynch syndrome (LS) and for his own PC status. PC occurrences (N = 36,360) were classified into one or more subtypes: early onset (EO), lethal, and/or clinically significant. Relative risks (RRs) associated with each subtype, adjusted for important covariables, were calculated in STATA using a modified Poisson regression with robust error variances to obtain corresponding RR CIs for each FH definition.

RESULTS

An FH of HPC conveyed the greatest relative risk for all PC subtypes combined (RR, 2.30; 95% CI, 2.22 to 2.40), followed by HBOC and LS (both with 1 < RR < 2 and statistically significant). The strongest risks associated with FH were observed for EO disease in all pedigree types, consistent with the contribution of genetic factors to disease occurrence.

CONCLUSION

In this large, population-based, family database, the risk of PC varied by cancer FH and was most strongly associated with EO disease. These results are critically valuable in understanding and targeting high-risk populations that would benefit from genetic screening and enhanced surveillance.

The Genomic and Molecular Pathology of Prostate Cancer: Clinical Implications for Diagnosis, Prognosis, and Therapy

Prostate cancer (PCa) is the most common noncutaneous malignancy affecting American men and the second most common cause of cancer death. The traditional risk classification schemes for PCa are limited due to the vast clinical and molecular heterogeneity of the disease. Fortunately, recent advancements in sequencing technologies have provided us with valuable insight into the genomics of PCa. To date, a wide array of recurrent genomic alterations in PCa have been identified. Incorporating these distinct molecular subtypes of PCa into prediction models provides opportunities for improved risk stratification and ultimately better patient outcomes. In this review, we summarize the key molecular subtypes of PCa and focus on those genomic alterations that have clinical implications for diagnosis, prognosis, and therapeutic response.

The Role of BRCA Testing in Hereditary Pancreatic and Prostate Cancer Families

Beyond breast and ovarian cancers, mutations in the BRCA1 and BRCA2 genes increase risks for pancreatic and prostate cancers and contribute to the prevalence of these cancers. Mutations in a number of other genes have also been shown to increase the risk for these cancers as well. Genetic testing is playing an increasingly important role in the treatment of patients with pancreatic and prostate cancer and is now recommended for all patients with pancreatic or metastatic prostate cancer, as well as patients with high Gleason grade prostate cancer and a remarkable family history. Identification of an inherited mutation can direct evaluation of the patient for other cancer risks as well as identification and management of disease in at-risk relatives. Growing evidence suggests improved responses to PARP inhibitors and other therapies in patients with mutations in the BRCA and other DNA repair genes. Although more work must be done to clarify the prevalence and penetrance of mutations in genes other than BRCA1 and BRCA2 in patients with pancreatic and prostate cancer, in most cases, testing is now being done with a panel of multiple genes. Because of the complexities in panel testing and the increased likelihood of finding variants of uncertain significance, pre- and post-test genetic counseling are essential.

Rare germline variants in DNA repair genes and the angiogenesis pathway predispose prostate cancer patients to develop metastatic disease

BACKGROUND

Prostate cancer (PrCa) demonstrates a heterogeneous clinical presentation ranging from largely indolent to lethal. We sought to identify a signature of rare inherited variants that distinguishes between these two extreme phenotypes.

METHODS

We sequenced germline whole exomes from 139 aggressive (metastatic, age of diagnosis < 60) and 141 non-aggressive (low clinical grade, age of diagnosis ≥60) PrCa cases. We conducted rare variant association analyses at gene and gene set levels using SKAT and Bayesian risk index techniques. GO term enrichment analysis was performed for genes with the highest differential burden of rare disruptive variants.

RESULTS

Protein truncating variants (PTVs) in specific DNA repair genes were significantly overrepresented among patients with the aggressive phenotype, with BRCA2, ATM and NBN the most frequently mutated genes. Differential burden of rare variants was identified between metastatic and non-aggressive cases for several genes implicated in angiogenesis, conferring both deleterious and protective effects.

CONCLUSIONS

Inherited PTVs in several DNA repair genes distinguish aggressive from non-aggressive PrCa cases. Furthermore, inherited variants in genes with roles in angiogenesis may be potential predictors for risk of metastases. If validated in a larger dataset, these findings have potential for future clinical application.

Prostate Cancer Genomics: Recent Advances and the Prevailing Underrepresentation from Racial and Ethnic Minorities

Prostate cancer (CaP) is the most commonly diagnosed non-cutaneous cancer and the second leading cause of male cancer deaths in the United States. Among African American (AA) men, CaP is the most prevalent malignancy, with disproportionately higher incidence and mortality rates. Even after discounting the influence of socioeconomic factors, the effect of molecular and genetic factors on racial disparity of CaP is evident. Earlier studies on the molecular basis for CaP disparity have focused on the influence of heritable mutations and single-nucleotide polymorphisms (SNPs). Most CaP susceptibility alleles identified based on genome-wide association studies (GWAS) were common, low-penetrance variants. Germline CaP-associated mutations that are highly penetrant, such as those found in HOXB13 and BRCA2, are usually rare. More recently, genomic studies enabled by Next-Gen Sequencing (NGS) technologies have focused on the identification of somatic mutations that contribute to CaP tumorigenesis. These studies confirmed the high prevalence of ERG gene fusions and PTEN deletions among Caucasian Americans and identified novel somatic alterations in SPOP and FOXA1 genes in early stages of CaP. Individuals with African ancestry and other minorities are often underrepresented in these large-scale genomic studies, which are performed primarily using tumors from men of European ancestry. The insufficient number of specimens from AA men and other minority populations, together with the heterogeneity in the molecular etiology of CaP across populations, challenge the generalizability of findings from these projects. Efforts to close this gap by sequencing larger numbers of tumor specimens from more diverse populations, although still at an early stage, have discovered distinct genomic alterations. These research findings can have a direct impact on the diagnosis of CaP, the stratification of patients for treatment, and can help to address the disparity in incidence and mortality of CaP. This review examines the progress of understanding in CaP genetics and genomics and highlight the need to increase the representation from minority populations.

Impact of the G84E variant on HOXB13 gene and protein expression in formalin-fixed, paraffin-embedded prostate tumours

The HOXB13 G84E variant is associated with risk of prostate cancer (PCa), however the role this variant plays in PCa development is unknown. This study examined 751 cases, 450 relatives and 355 controls to determine the contribution of this variant to PCa risk in Tasmania and investigated HOXB13 gene and protein expression in tumours from nine G84E heterozygote variant and 13 wild-type carriers. Quantitative PCR and immunohistochemistry showed that HOXB13 gene and protein expression did not differ between tumour samples from variant and wild-type carriers. Allele-specific transcription revealed that two of seven G84E carriers transcribed both the variant and wild-type allele, while five carriers transcribed the wild-type allele. Methylation of surrounding CpG sites was lower in the variant compared to the wild-type allele, however overall methylation across the region was very low. Notably, tumour characteristics were less aggressive in the two variant carriers that transcribed the variant allele compared to the five that did not. This study has shown that HOXB13 expression does not differ between tumour tissue of G84E variant carriers and non-carriers. Intriguingly, the G84E variant allele was rarely transcribed in carriers, suggesting that HOXB13 expression may be driven by the wild-type allele in the majority of carriers.

Somatic molecular subtyping of prostate tumors from HOXB13 G84E carriers

A recurrent germline mutation (G84E) in the HOXB13 gene is associated with early onset and family history-positive prostate cancer in patients of European descent, occurring in up to 5% of prostate cancer families. To date, the molecular features of prostate tumors occurring in HOXB13 G84E carriers have not been studied in a large cohort of patients. We identified 101 heterozygous carriers of G84E who underwent radical prostatectomy for prostate cancer between 1985 and 2011 and matched these men by race, age and tumor grade to 99 HOXB13 wild-type controls. Immunostaining for HOXB13, PTEN, ERG, p53 and SPINK1 as well as RNA in situ hybridization for ETV1/4/5 were performed using genetically validated assays. Tumors from G84E carriers generally expressed HOXB13 protein at a level comparable to benign and wild-type glands. ETS gene expression (either ERG or ETV1/4/5) was seen in 36% (36/101) of tumors from G84E carriers compared to 68% (65/96) of the controls (p < 0.0001). PTEN was lost in 11% (11/101) of G84E carriers compared to 25% (25/99) of the controls (p = 0.014). PTEN loss was enriched among ERG-positive compared to ERG-negative tumors in both groups of patients. Nuclear accumulation of the p53 protein, indicative of underlying TP53 missense mutations, was uncommon in both groups, occurring in 1% (1/101) of the G84E carriers versus 2% (2/92) of the controls (p = NS). Taken together, these data suggest that genes other than ERG and PTEN may drive carcinogenesis/progression in the majority of men with germline HOXB13 mutations.

Familial prostate cancer

Prostate cancer is the most commonly diagnosed cancer among men in the United States as well as most Western countries. A significant proportion of men report having a positive family history of prostate cancer in a first-degree relative (father, brother, son), which is important in that family history is one of the only established risk factors for the disease and plays a role in decision-making for prostate cancer screening. Familial aggregation of prostate cancer is considered a surrogate marker of genetic susceptibility to developing the disease, but shared environment cannot be excluded as an explanation for clustering of cases among family members. Prostate cancer is both a clinically and genetically heterogeneous disease with inherited factors predicted to account for 40%-50% of cases, comprised of both rare highly to moderately penetrant gene variants, as well as common genetic variants of low penetrance. Most notably, HOXB13 and BRCA2 mutations have been consistently shown to increase prostate cancer risk, and are more commonly observed among patients diagnosed with early-onset disease. A recurrent mutation in HOXB13 has been shown to predispose to hereditary prostate cancer (HPC), and BRCA2 mutations to hereditary breast and ovarian cancer (HBOC). Genome-wide association studies (GWAS) have also identified approximately 100 loci that associate with modest (odds ratios <2.0) increases in prostate cancer risk, only some of which have been replicated in subsequent studies. Despite these efforts, genetic testing in prostate cancer lags behind other common tumors like breast and colorectal cancer. To date, National Comprehensive Cancer Network (NCCN) guidelines have highly selective criteria for BRCA1/2 testing for men with prostate cancer based on personal history and/or specific family cancer history. Tumor sequencing is also leading to the identification of germline mutations in prostate cancer patients, informing the scope of inheritance. Advances in genetic testing for inherited and familial prostate cancer (FPC) are needed to inform personalized cancer risk screening and treatment approaches.

Regulating NKX3.1 stability and function: Post-translational modifications and structural determinants

BACKGROUND

The androgen-regulated homeodomain transcription factor NKX3.1 plays roles in early prostate development and functions as a prostate-specific tumor suppressor. Decreased expression of NKX3.1 protein is common in primary prostate cancer. Discordance between NKX3.1 mRNA and protein levels during prostate carcinogenesis suggested a key role for post-transcriptional modifications in regulating NKX3.1 protein levels in prostate epithelial cells. Subsequent studies revealed NKX3.1 to be modified post-translationally at multiple sites.

METHODS

We reviewed published literature to identify and summarize post-translational modifications and structural elements critical in regulating NKX3.1 stability and levels in prostate epithelial cells.

RESULTS

NKX3.1 is modified post-translationally at multiple sites by different protein kinases. These modifications together with several structural determinants were identified to play an important role in NKX3.1 stability and biology.

CONCLUSIONS

In this review, we provide a comprehensive overview of the known post-translational modifications and structural features that impact NKX3.1. Defining factors that regulate NKX3.1 in prostate epithelial cells will extend our understanding of molecular changes that may contribute to prostate cancer initiation and progression.

Prevalence of the HOXB13 G84E mutation in Danish men undergoing radical prostatectomy and its correlations with prostate cancer risk and aggressiveness

OBJECTIVES

To determine the prevalence of the HOXB13 G84E mutation (rs138213197) in Danish men with or without prostate cancer (PCa) and to investigate possible correlations between HOXB13 mutation status and clinicopathological characteristics associated with tumour aggressiveness.

MATERIALS AND METHODS

We conducted a case-control study including 995 men with PCa (cases) who underwent radical prostatectomy (RP) between 1997 and 2011 at the Department of Urology, Aarhus University Hospital, Denmark. As controls, we used 1622 healthy men with a normal prostate specific antigen (PSA) level.

RESULTS

The HOXB13 G84E mutation was identified in 0.49% of controls and in 2.51% of PCa cases. The mutation was associated with a 5.12-fold increased relative risk (RR) of PCa (95% confidence interval [CI] 2.26-13.38; P = 13 × 10(-6) ). Furthermore, carriers of the risk allele were significantly more likely to have a higher PSA level at diagnosis (mean PSA 19.9 vs 13.6 ng/mL; P = 0.032), a pathological Gleason score ≥7 (83.3 vs 60.9%; P = 0.032), and positive surgical margins (56.0 vs 28.5%; P = 0.006) than non-carriers. Risk allele carriers were also more likely to have aggressive disease (54.2 vs 28.6%; P = 0.011), as defined by a preoperative PSA ≥20 ng/mL, pathological Gleason score ≥ (4+3) and/or presence of regional/distant disease. At a mean follow-up of 7 months, we found no significant association between HOXB13 mutation status and biochemical recurrence in this cohort of men who underwent RP.

CONCLUSIONS

This is the first study to investigate the HOXB13 G84E mutation in Danish men. The mutation was detected in 0.49% of controls and in 2.51% of cases, and was associated with 5.12-fold increased RR of being diagnosed with PCa. In our RP cohort, HOXB13 mutation carriers were more likely to develop aggressive PCa. Further studies are needed to assess the potential of HOXB13 for future targeted screening approaches.

Stage at presentation and survival outcomes of patients with Gleason 8-10 prostate cancer and low prostate-specific antigen

OBJECTIVE

To evaluate outcomes for men with high Gleason score and low prostate-specific antigen (PSA) prostate cancer. Low PSA levels among men with Gleason 8-10 prostate cancer may be owing to cellular dedifferentiation rather than low disease burden. We hypothesized that men with Gleason 8-10 prostate cancer and low PSA levels have increased risk for advanced disease and worse survival.

MATERIALS AND METHODS

Men diagnosed from 2004 to 2007 with Gleason 8-10 prostate adenocarcinoma in the National Cancer Data Base were included. Patients were stratified by PSA levels at diagnosis: 0.1 to 3.9, 4.0 to 9.9, 10.0 to 19.9, and≥20.0ng/ml. Outcomes were clinical TNM category, pathologic stage (for prostatectomy patients), and overall survival (OS). Kaplan-Meier analysis and Cox proportional hazards models were used.

RESULTS

A total of 37,283 patients were included. Men with PSA levels of<4.0ng/ml were more likely than those with PSA levels of 4 to 9.9ng/ml to present with clinical T3-4 disease (15% vs. 10%, P<0.001), nodal (4% vs. 2%, P<0.001) and distant (5% vs. 3%, P<0.001) metastasis. However, among patients treated with prostatectomy, lower PSA levels were not associated with increased likelihood of pathologic T3-4 disease or nodal metastasis. Six-year OS was 89.1% (PSA: 0.1-3.9ng/ml) vs. 91.0% (PSA: 4.0-9.9ng/ml) for prostatectomy (log-rank P<0.001), and 75.8% vs. 81.0% for radiotherapy (P<0.001). Multivariable analyses showed OS of patients with PSA levels of 0.1 to 3.9ng/ml to be similar to those with PSA levels of 10 to 19.9ng/ml.

CONCLUSIONS

Patients with Gleason 8-10 cancer and PSA levels of<4.0ng/ml have more aggressive disease than those with PSA levels of 4 to 9.9ng/ml; these low PSA cancers behave more like those with PSA levels of 10 to 19.9ng/ml. Further study is needed to evaluate potential biological differences in these patients with low PSA-producing cancers.

A positive family history as a risk factor for prostate cancer in a population-based study with organised prostate-specific antigen screening: results of the Swiss European Randomised Study of Screening for Prostate Cancer (ERSPC, Aarau)

OBJECTIVE

To assess the value of a positive family history (FH) as a risk factor for prostate cancer incidence and grade among men undergoing organised prostate-specific antigen (PSA) screening in a population-based study.

SUBJECTS AND METHODS

The study cohort comprised all attendees of the Swiss arm of the European Randomised Study of Screening for Prostate Cancer (ERSPC) with systematic PSA level tests every 4 years. Men reporting first-degree relative(s) diagnosed with prostate cancer were considered to have a positive FH. Biopsy was exclusively PSA triggered at a PSA level threshold of 3 ng/mL. The primary endpoint was prostate cancer diagnosis. Kaplan-Meier and Cox regression analyses were used.

RESULTS

Of 4 932 attendees with a median (interquartile range, IQR) age of 60.9 (57.6-65.1) years, 334 (6.8%) reported a positive FH. The median (IQR) follow-up duration was 11.6 (10.3-13.3) years. Cumulative prostate cancer incidence was 60/334 (18%, positive FH) and 550/4 598 (12%, negative FH) [odds ratio 1.6, 95% confidence interval (CI) 1.2-2.2, P = 0.001). In both groups, most prostate cancer diagnosed was low grade. There were no significant differences in PSA level at diagnosis, biopsy Gleason score or Gleason score on pathological specimen among men who underwent radical prostatectomy between both groups. On multivariable analysis, age (hazard ratio [HR] 1.04, 95% CI 1.02-1.06), baseline PSA level (HR 1.13, 95% CI 1.12-1.14), and FH (HR 1.6, 95% CI 1.24-2.14) were independent predictors for overall prostate cancer incidence (all P < 0.001). Only baseline PSA level (HR 1.14, 95% CI 1.12-1.16, P < 0.001) was an independent predictor of Gleason score ≥7 prostate cancer on prostate biopsy. The proportion of interval prostate cancer diagnosed in-between the screening rounds was not significantly different.

CONCLUSION

Irrespective of the FH status, the current PSA-based screening setting detects the majority of aggressive prostate cancers and missed only a minority of interval cancers with a 4-year screening algorithm. Our results suggest that men with a positive FH are at increased risk of low-grade but not aggressive prostate cancer.

The HOXB13 G84E Mutation Is Associated with an Increased Risk for Prostate Cancer and Other Malignancies

BACKGROUND

A rare nonconservative substitution (G84E) in the HOXB13 gene has been shown to be associated with risk of prostate cancer. DNA samples from male patients included in the Mayo Clinic Biobank (MCB) were genotyped to determine the frequency of the G84E mutation and its association with various cancers.

METHODS

Subjects were genotyped using a custom TaqMan (Applied Biosystems) assay for G84E (rs138213197). In addition to donating a blood specimen, all MCB participants completed a baseline questionnaire to collect information on medical history and family history of cancer.

RESULTS

Forty-nine of 9,012 male patients were carriers of G84E (0.5%). Thirty-one percent (n = 2,595) of participants had been diagnosed with cancer, including 51.1% of G84E carriers compared with just 30.6% of noncarriers (P = 0.004). G84E was most frequently observed among men with prostate cancer compared with men without cancer (P < 0.0001). However, the mutation was also more commonly observed in men with bladder cancer (P = 0.06) and leukemia (P = 0.01). G84E carriers were more likely to have a positive family history of prostate cancer in a first-degree relative compared to noncarriers (36.2% vs. 16.0%, P = 0.0003).

CONCLUSIONS

Our study confirms the association between the HOXB13 G84E variant and prostate cancer and suggests a novel association between G84E and leukemia and a suggestive association with bladder cancer. Future investigation is warranted to confirm these associations in order to improve our understanding of the role of germline HOXB13 mutations in human cancer.

IMPACT

The associations between HOXB13 and prostate, leukemia, and bladder suggest that this gene is important in carcinogenesis.

Prevalence of the HOXB13 G84E germline mutation in British men and correlation with prostate cancer risk, tumour characteristics and clinical outcomes

BACKGROUND

A rare recurrent missense variant in HOXB13 (rs138213197/G84E) was recently reported to be associated with hereditary prostate cancer. Population-based studies have established that, since the frequency of this single-nucleotide polymorphism (SNP) varies between geographic regions, the associated proportion of prostate cancer (PrCa) risk contribution is also highly variable by country.

PATIENTS AND METHODS

This is the largest comprehensive case-control study assessing the prevalence of the HOXB13 G84E variant to date and is the first in the UK population. We genotyped 8652 men diagnosed with PrCa within the UK Genetic Prostate Cancer Study (UKGPCS) and 5252 healthy men from the UK ProtecT study.

RESULTS

HOXB13 G84E was identified in 0.5% of the healthy controls and 1.5% of the PrCa cases, and it was associated with a 2.93-fold increased risk of PrCa [95% confidence interval (CI) 1.94-4.59; P = 6.27 × 10(-8)]. The risk was even higher among men with family history of PrCa [odds ratio (OR) = 4.53, 95% CI 2.86-7.34; P = 3.1 × 10(-8)] and in young-onset PrCa (diagnosed up to the age of 55 years; OR = 3.11, 95% CI 1.98-5.00; P = 6.1 × 10(-7)). There was no significant association between Gleason Score, presenting prostate specific antigen, tumour-node-metastasis (TNM) stage or NCCN risk group and carrier status. HOXB13 G84E was not associated with overall or cancer-specific survival. We found that the polygenic PrCa risk score (PR score), calculated using the 71 known single-nucleotide polymorphisms (SNPs) associated with PrCa and the HOXB13 G84E variant act multiplicatively on PrCa risk. Based on the estimated prevalence and risk, this rare variant explains ∼1% of the familial risk of PrCa in the UK population.

CONCLUSIONS

The clinical importance of HOXB13 G84E in PrCa management has not been established. This variant was found to have no effect on prognostic implications but could be used for stratifying screening, by identifying men at high risk.

CLINICAL TRIALS NUMBERS

Prostate Testing for Cancer and Treatment (ProtecT): NCT02044172.

UK GENETIC PROSTATE CANCER STUDY

Epidemiology and Molecular Genetics Studies (UKGPCS): NCT01737242.

Identification of a novel germline SPOP mutation in a family with hereditary prostate cancer

BACKGROUND

Family history of prostate cancer is a well-recognized risk factor. Previous linkage studies have reported a putative prostate cancer susceptibility locus at chromosome 17q21-22. SPOP (Speckle-type POZ protein) maps to the 17q21-22 candidate linkage region and is one of the most frequently mutated genes in sporadic prostate cancers.

METHODS

We performed targeted next generation sequencing to analyze 2009 exons from 202 genes in a candidate linkage region on chromosome 17q21-22 using 94 unrelated familial prostate cancer cases from the University of Michigan Prostate Cancer Genetics Project (n=54) and Johns Hopkins University (n=40) including the exons and UTRs of SPOP.

RESULTS

We identified a novel SPOP missense mutation (N296I) in a man with prostate cancer diagnosed at age 43. This mutation completely segregates with prostate cancer affection status among the men in this family. The N296I mutation resides within the evolutionarily conserved Bric-a-brac, Tramtrack, Broad-complex (BTB) domain, involved in recruiting targets to Cul3 for degradation. Analysis of the prostate tumor from this individual verified the presence of heterozygous N296I as well as an ERG fusion.

CONCLUSIONS

We have discovered a novel mutation in SPOP that tracks with prostate cancer within a family and is predicted to be deleterious. Taken together, our results implicate SPOP as a candidate gene for hereditary prostate cancer.