Rare germline mutations in African American men diagnosed with early-onset prostate cancer

BACKGROUND

African Americans have both a higher incidence of prostate cancer and greater disease-specific mortality compared with non-Hispanic whites. Historically, the investigation of the contribution of rare genetic variants to prostate cancer in African American men has been hampered by low participation in large genetic studies, particularly those focused on early-onset and familial disease.

METHODS

We sequenced 160 genes purported to be involved in carcinogenic pathways in germline DNA samples collected from 96 African American men diagnosed with early-onset prostate cancer (≤55 years at diagnosis). REVEL software was used to determine the pathogenic potential of observed missense variants.

RESULTS

We observed three protein-truncating mutations, one in BRCA2 and two in BRIP1 in three African American men diagnosed with early-onset prostate cancer. Furthermore, we observed five rare, mostly private, missense variants among four genes (BRCA1, BRCA2, PMS2, and ATM) that were predicted to be deleterious and hence likely pathogenic in our patient sample.

CONCLUSIONS

Protein-truncating mutations in BRCA2 and BRIP1 were discovered in African American men diagnosed with early-onset prostate cancer. Further study is necessary to determine the role of rare, missense variants to prostate cancer incidence, and progression in this group of high-risk men.

Genome-wide association of familial prostate cancer cases identifies evidence for a rare segregating haplotype at 8q24.21

Previous genome-wide association studies (GWAS) of prostate cancer risk focused on cases unselected for family history and have reported over 100 significant associations. The International Consortium for Prostate Cancer Genetics (ICPCG) has now performed a GWAS of 2511 (unrelated) familial prostate cancer cases and 1382 unaffected controls from 12 member sites. All samples were genotyped on the Illumina 5M+exome single nucleotide polymorphism (SNP) platform. The GWAS identified a significant evidence for association for SNPs in six regions previously associated with prostate cancer in population-based cohorts, including 3q26.2, 6q25.3, 8q24.21, 10q11.23, 11q13.3, and 17q12. Of note, SNP rs138042437 (p = 1.7e(-8)) at 8q24.21 achieved a large estimated effect size in this cohort (odds ratio = 13.3). 116 previously sampled affected relatives of 62 risk-allele carriers from the GWAS cohort were genotyped for this SNP, identifying 78 additional affected carriers in 62 pedigrees. A test for an excess number of affected carriers among relatives exhibited strong evidence for co-segregation of the variant with disease (p = 8.5e(-11)). The majority (92 %) of risk-allele carriers at rs138042437 had a consistent estimated haplotype spanning approximately 100 kb of 8q24.21 that contained the minor alleles of three rare SNPs (dosage minor allele frequencies <1.7 %), rs183373024 (PRNCR1), previously associated SNP rs188140481, and rs138042437 (CASC19). Strong evidence for co-segregation of a SNP on the haplotype further characterizes the haplotype as a prostate cancer predisposition locus.

Assessing the Cumulative Contribution of New and Established Common Genetic Risk Factors to Early-Onset Prostate Cancer

BACKGROUND

We assessed the evidence for association between 23 recently reported prostate cancer variants and early-onset prostate cancer and the aggregate value of 63 prostate cancer variants for predicting early-onset disease using 931 unrelated men diagnosed with prostate cancer prior to age 56 years and 1,126 male controls.

METHODS

Logistic regression models were used to test the evidence for association between the 23 new variants and early-onset prostate cancer. Weighted and unweighted sums of total risk alleles across these 23 variants and 40 established variants were constructed. Weights were based on previously reported effect size estimates. Receiver operating characteristic curves and forest plots, using defined cut-points, were constructed to assess the predictive value of the burden of risk alleles on early-onset disease.

RESULTS

Ten of the 23 new variants demonstrated evidence (P < 0.05) for association with early-onset prostate cancer, including four that were significant after multiple test correction. The aggregate burden of risk alleles across the 63 variants was predictive of early-onset prostate cancer (AUC = 0.71 using weighted sums), especially in men with a high burden of total risk alleles.

CONCLUSIONS

A high burden of risk alleles is strongly associated with early-onset prostate cancer.

IMPACT

Our results provide the first formal replication for several of these 23 new variants and demonstrate that a high burden of common-variant risk alleles is a major risk factor for early-onset prostate cancer. Cancer Epidemiol Biomarkers Prev; 25(5); 766-72. ©2015 AACR.

Mutational landscape of candidate genes in familial prostate cancer

BACKGROUND

Family history is a major risk factor for prostate cancer (PCa), suggesting a genetic component to the disease. However, traditional linkage and association studies have failed to fully elucidate the underlying genetic basis of familial PCa.

METHODS

Here, we use a candidate gene approach to identify potential PCa susceptibility variants in whole exome sequencing data from familial PCa cases. Six hundred ninety-seven candidate genes were identified based on function, location near a known chromosome 17 linkage signal, and/or previous association with prostate or other cancers. Single nucleotide variants (SNVs) in these candidate genes were identified in whole exome sequence data from 33 PCa cases from 11 multiplex PCa families (3 cases/family).

RESULTS

Overall, 4,856 candidate gene SNVs were identified, including 1,052 missense and 10 nonsense variants. Twenty missense variants were shared by all three family members in each family in which they were observed. Additionally, 15 missense variants were shared by two of three family members and predicted to be deleterious by five different algorithms. Four missense variants, BLM Gln123Arg, PARP2 Arg283Gln, LRCC46 Ala295Thr and KIF2B Pro91Leu, and one nonsense variant, CYP3A43 Arg441Ter, showed complete co-segregation with PCa status. Twelve additional variants displayed partial co-segregation with PCa.

CONCLUSIONS

Forty-three nonsense and shared, missense variants were identified in our candidate genes. Further research is needed to determine the contribution of these variants to PCa susceptibility.

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.

HOXB13 G84E-related familial prostate cancers: a clinical, histologic, and molecular survey

Recent genetic epidemiologic studies identified a germline mutation in the homeobox transcription factor, HOXB13 G84E, which is associated with markedly increased risk for prostate cancer, particularly early-onset hereditary prostate cancer. The histomorphologic and molecular features of cancers arising in such carriers have not been studied. Here, we reviewed prostatectomy specimens from 23 HOXB13 G84E mutation carriers, mapping the total cancer burden by anatomically distinct cancer focus and evaluating morphologic features. We also assessed basic molecular subtypes for all cancer foci (ERG/SPINK1 status) by dual immunohistochemistry staining on full sections. The cohort showed a median age of 58 years, a median serum PSA level of 5.7 ng/mL, and a median of 6 cancer foci (range, 1 to 14) per case. Of evaluable cases, dominant foci were Gleason score 6 in 23%, 3+4=7 in 41%, 4+3=7 in 23%, and ≥8 in 14%; biochemical recurrence was observed in 1 case over a median of 36 months follow-up. Histologic review found a high prevalence of cases showing cancers with a spectrum of features previously described with pseudohyperplastic carcinomas, with 45% of cases showing a dominant focus with such features. Molecular subtyping revealed a strikingly low prevalence of ERG cancer with increased prevalence of SPINK1 cancer (dominant focus ERG 17%, SPINK1 26%, ERG/SPINK1 52%, single ERG/SPINK1 focus 4%). One ERG/SPINK1 dominant focus showed aberrant p63 immunophenotype. In summary, HOXB13 G84E variant-related prostate cancers show frequent pseudohyperplastic-type features and markedly low prevalence of ERG cancers relative to unselected cases and, especially, to early-onset cohorts. These findings suggest that novel molecular pathways may drive disease in HOXB13 G84E carriers.

Genome-wide association scan for variants associated with early-onset prostate cancer

Prostate cancer is the most common non-skin cancer and the second leading cause of cancer related mortality for men in the United States. There is strong empirical and epidemiological evidence supporting a stronger role of genetics in early-onset prostate cancer. We performed a genome-wide association scan for early-onset prostate cancer. Novel aspects of this study include the focus on early-onset disease (defined as men with prostate cancer diagnosed before age 56 years) and use of publically available control genotype data from previous genome-wide association studies. We found genome-wide significant (p<5×10⁻⁸) evidence for variants at 8q24 and 11p15 and strong supportive evidence for a number of previously reported loci. We found little evidence for individual or systematic inflated association findings resulting from using public controls, demonstrating the utility of using public control data in large-scale genetic association studies of common variants. Taken together, these results demonstrate the importance of established common genetic variants for early-onset prostate cancer and the power of including early-onset prostate cancer cases in genetic association studies.

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

OBJECTIVE

To determine the prevalence and clinical correlates of the G84E mutation in the homeobox transcription factor, or HOXB13, gene using DNA samples from 9559 men with prostate cancer undergoing radical prostatectomy.

PATIENTS AND METHODS

DNA samples from men treated with radical prostatectomy at the University of Michigan and John Hopkins University were genotyped for G84E and this was confirmed by Sanger sequencing. The frequency and distribution of this allele was determined according to specific patient characteristics (family history, age at diagnosis, pathological Gleason grade and stage).

RESULTS

Of 9559 patients, 128 (1.3%) were heterozygous carriers of G84E. Patients who possessed the variant were more likely to have a family history of prostate cancer than those who did not (46.0 vs 35.4%; P = 0.006). G84E carriers were also more likely to be diagnosed at a younger age than non-carriers (55.2 years vs 58.1 years; P < 0.001). No difference in the proportion of patients diagnosed with high grade or advanced stage tumours according to carrier status was observed.

CONCLUSIONS

In the present study, carriers of the rare G84E variant in HOXB13 were both younger at the time of diagnosis and more likely to have a family history of prostate cancer compared with homozygotes for the wild-type allele. No significant differences in allele frequency were detected according to selected clinical characteristics of prostate cancer. Further investigation is required to evaluate the role of HOXB13 in prostate carcinogenesis.

Association analysis of 9,560 prostate cancer cases from the International Consortium of Prostate Cancer Genetics confirms the role of reported prostate cancer associated SNPs for familial disease

Previous GWAS studies have reported significant associations between various common SNPs and prostate cancer risk using cases unselected for family history. How these variants influence risk in familial prostate cancer is not well studied. Here, we analyzed 25 previously reported SNPs across 14 loci from prior prostate cancer GWAS. The International Consortium for Prostate Cancer Genetics (ICPCG) previously validated some of these using a family-based association method (FBAT). However, this approach suffered reduced power due to the conditional statistics implemented in FBAT. Here, we use a case-control design with an empirical analysis strategy to analyze the ICPCG resource for association between these 25 SNPs and familial prostate cancer risk. Fourteen sites contributed 12,506 samples (9,560 prostate cancer cases, 3,368 with aggressive disease, and 2,946 controls from 2,283 pedigrees). We performed association analysis with Genie software which accounts for relationships. We analyzed all familial prostate cancer cases and the subset of aggressive cases. For the familial prostate cancer phenotype, 20 of the 25 SNPs were at least nominally associated with prostate cancer and 16 remained significant after multiple testing correction (p ≤ 1E (-3)) occurring on chromosomal bands 6q25, 7p15, 8q24, 10q11, 11q13, 17q12, 17q24, and Xp11. For aggressive disease, 16 of the SNPs had at least nominal evidence and 8 were statistically significant including 2p15. The results indicate that the majority of common, low-risk alleles identified in GWAS studies for all prostate cancer also contribute risk for familial prostate cancer, and that some may contribute risk to aggressive disease.

Abstract 2564: Identification of a novel SPOP missense mutation from targeted next-generation sequencing of men with chromosome 17-q linkage

Speckle-type POZ protein (SPOP), located on chromosome 17q21, encodes the substrate-binding subunit of a Cullin-based E3 ubiquitin ligase gene. The SPOP gene has been shown to be one of the most commonly mutated genes in studies focused on characterization of somatic mutations in prostate tumors. In light of the evidence for prostate cancer linkage to chromosome 17q21-22 markers, we hypothesized that germline variation in SPOP may increase the risk for prostate cancer. 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 selected from multiplex prostate cancer families based on evidence of linkage to chromosome 17q21-22. Germline DNA samples were subjected to targeted next-generation sequencing of more than 200 genes in the candidate region which included the exons and UTRs of SPOP. One individual, diagnosed with prostate cancer at age 43, was identified to have a novel missense mutation in exon 10 of the gene which results in an amino acid substitution of asparagine to isoleucine at codon 296 (N296I). Tumor DNA from this individual was positive for LOH at neighboring marker D17S943 as well as an ERG fusion documented by immunohistochemistry. Sanger sequencing was performed using genomic DNA from five additional male relatives and two female relatives. Notably, the N296I mutation completely segregates with prostate cancer affection status among the men in this family; the father and a brother with prostate cancer also carry the mutation, as does another brother affected with both prostate and kidney cancer. The mother and two unaffected brothers do not carry the N296I allele, however the sister of the proband was positive for the variant. To our knowledge, neither of the female relatives has been diagnosed with cancer. The SPOP N296I mutation was not detected in genomic DNA samples from a set of 1411 siblings with and without prostate cancer (775 cases and 636 controls) from 573 families. The N296I mutation is present in the evolutionarily conserved Bric-a-brac, Tramtrack, Broad-complex (BTB) domain. Changes to BTB may affect the ability of SPOP to recruit targets to Cul3 for degradation, thus suggesting a role for SPOP mutations in prostate cancer susceptibility. In conclusion, analysis of a set of chromosome 17q21-22 linked families has led to the identification of a novel rare missense mutation in the SPOP gene and further studies are ongoing to determine the potential role of this variant in prostate cancer susceptibility.

Citation Format: Kimberly A. Zuhlke, Anna M. Johnson, Scott A. Tomlins, Nallasivam Palanisamy, Christiane M. Robbins, Waibhav A. Tembe, John D. Carpten, Ethan M. Lange, William B. Isaacs, Kathleen A. Cooney. Identification of a novel SPOP missense mutation from targeted next-generation sequencing of men with chromosome 17-q linkage. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2564. doi:10.1158/1538-7445.AM2013-2564

HOXB13 is a susceptibility gene for prostate cancer: results from the International Consortium for Prostate Cancer Genetics (ICPCG)

Prostate cancer has a strong familial component but uncovering the molecular basis for inherited susceptibility for this disease has been challenging. Recently, a rare, recurrent mutation (G84E) in HOXB13 was reported to be associated with prostate cancer risk. Confirmation and characterization of this finding is necessary to potentially translate this information to the clinic. To examine this finding in a large international sample of prostate cancer families, we genotyped this mutation and 14 other SNPs in or flanking HOXB13 in 2,443 prostate cancer families recruited by the International Consortium for Prostate Cancer Genetics (ICPCG). At least one mutation carrier was found in 112 prostate cancer families (4.6 %), all of European descent. Within carrier families, the G84E mutation was more common in men with a diagnosis of prostate cancer (194 of 382, 51 %) than those without (42 of 137, 30 %), P = 9.9 × 10(-8) [odds ratio 4.42 (95 % confidence interval 2.56-7.64)]. A family-based association test found G84E to be significantly over-transmitted from parents to affected offspring (P = 6.5 × 10(-6)). Analysis of markers flanking the G84E mutation indicates that it resides in the same haplotype in 95 % of carriers, consistent with a founder effect. Clinical characteristics of cancers in mutation carriers included features of high-risk disease. These findings demonstrate that the HOXB13 G84E mutation is present in ~5 % of prostate cancer families, predominantly of European descent, and confirm its association with prostate cancer risk. While future studies are needed to more fully define the clinical utility of this observation, this allele and others like it could form the basis for early, targeted screening of men at elevated risk for this common, clinically heterogeneous cancer.

Validation of prostate cancer risk-related loci identified from genome-wide association studies using family-based association analysis: evidence from the International Consortium for Prostate Cancer Genetics (ICPCG)

Multiple prostate cancer (PCa) risk-related loci have been discovered by genome-wide association studies (GWAS) based on case-control designs. However, GWAS findings may be confounded by population stratification if cases and controls are inadvertently drawn from different genetic backgrounds. In addition, since these loci were identified in cases with predominantly sporadic disease, little is known about their relationships with hereditary prostate cancer (HPC). The association between seventeen reported PCa susceptibility loci was evaluated with a family-based association test using 1,979 hereditary PCa families of European descent collected by members of the International Consortium for Prostate Cancer Genetics, with a total of 5,730 affected men. The risk alleles for 8 of the 17 loci were significantly over-transmitted from parents to affected offspring, including SNPs residing in 8q24 (regions 1, 2 and 3), 10q11, 11q13, 17q12 (region 1), 17q24 and Xp11. In subgroup analyses, three loci, at 8q24 (regions 1 and 2) plus 17q12, were significantly over-transmitted in hereditary PCa families with five or more affected members, while loci at 3p12, 8q24 (region 2), 11q13, 17q12 (region 1), 17q24 and Xp11 were significantly over-transmitted in HPC families with an average age of diagnosis at 65 years or less. Our results indicate that at least a subset of PCa risk-related loci identified by case-control GWAS are also associated with disease risk in HPC families.

Genetic variation in glutathione S-transferase omega-1, arsenic methyltransferase and methylene-tetrahydrofolate reductase, arsenic exposure and bladder cancer: a case-control study

BACKGROUND

Ingestion of groundwater with high concentrations of inorganic arsenic has been linked to adverse health outcomes, including bladder cancer, however studies have not consistently observed any elevation in risk at lower concentrations. Genetic variability in the metabolism and clearance of arsenic is an important consideration in any investigation of its potential health risks. Therefore, we examined the association between genes thought to play a role in the metabolism of arsenic and bladder cancer.

METHODS

Single nucleotide polymorphisms (SNPs) in GSTO-1, As3MT and MTHFR were genotyped using DNA from 219 bladder cancer cases and 273 controls participating in a case-control study in Southeastern Michigan and exposed to low to moderate (<50 μg/L) levels of arsenic in their drinking water. A time-weighted measure of arsenic exposure was constructed using measures from household water samples combined with past residential history, geocoded and merged with archived arsenic data predicted from multiple resources.

RESULTS

While no single SNP in As3MT was significantly associated with bladder cancer overall, several SNPs were associated with bladder cancer among those exposed to higher arsenic levels. Individuals with one or more copies of the C allele in rs11191439 (the Met287Thr polymorphism) had an elevated risk of bladder cancer (OR = 1.17; 95% CI = 1.04-1.32 per 1 μg/L increase in average exposure). However, no association was observed between average arsenic exposure and bladder cancer among TT homozygotes in the same SNP. Bladder cancer cases were also 60% less likely to be homozygotes for the A allele in rs1476413 in MTHFR compared to controls (OR = 0.40; 95% CI = 0.18-0.88).

CONCLUSIONS

Variation in As3MT and MTHFR is associated with bladder cancer among those exposed to relatively low concentrations of inorganic arsenic. Further investigation is warranted to confirm these findings.

Genetic variation in glutathione S-transferase omega-1, arsenic methyltransferase and methylene-tetrahydrofolate reductase, arsenic exposure and bladder cancer: a case-control study

BACKGROUND

Ingestion of groundwater with high concentrations of inorganic arsenic has been linked to adverse health outcomes, including bladder cancer, however studies have not consistently observed any elevation in risk at lower concentrations. Genetic variability in the metabolism and clearance of arsenic is an important consideration in any investigation of its potential health risks. Therefore, we examined the association between genes thought to play a role in the metabolism of arsenic and bladder cancer.

METHODS

Single nucleotide polymorphisms (SNPs) in GSTO-1, As3MT and MTHFR were genotyped using DNA from 219 bladder cancer cases and 273 controls participating in a case-control study in Southeastern Michigan and exposed to low to moderate (<50 μg/L) levels of arsenic in their drinking water. A time-weighted measure of arsenic exposure was constructed using measures from household water samples combined with past residential history, geocoded and merged with archived arsenic data predicted from multiple resources.

RESULTS

While no single SNP in As3MT was significantly associated with bladder cancer overall, several SNPs were associated with bladder cancer among those exposed to higher arsenic levels. Individuals with one or more copies of the C allele in rs11191439 (the Met287Thr polymorphism) had an elevated risk of bladder cancer (OR = 1.17; 95% CI = 1.04-1.32 per 1 μg/L increase in average exposure). However, no association was observed between average arsenic exposure and bladder cancer among TT homozygotes in the same SNP. Bladder cancer cases were also 60% less likely to be homozygotes for the A allele in rs1476413 in MTHFR compared to controls (OR = 0.40; 95% CI = 0.18-0.88).

CONCLUSIONS

Variation in As3MT and MTHFR is associated with bladder cancer among those exposed to relatively low concentrations of inorganic arsenic. Further investigation is warranted to confirm these findings.

Early onset prostate cancer has a significant genetic component

BACKGROUND

Prostate cancer (PCa) affects more than 190,000 men each year with ∼10% of men diagnosed at ≤55 years, that is, early onset (EO) PCa. Based on historical findings for other cancers, EO PCa likely reflects a stronger underlying genetic etiology.

METHODS

We evaluated the association between EO PCa and previously identified single nucleotide polymorphisms (SNPs) in 754 Caucasian cases from the Michigan Prostate Cancer Genetics Project (mean 49.8 years at diagnosis), 2,713 Caucasian controls from Illumina's iControlDB database and 1,163 PCa cases diagnosed at >55 years from the Cancer Genetic Markers of Susceptibility Study (CGEMS).

RESULTS

Significant associations existed for 13 of 14 SNPs (rs9364554 on 6q25, rs10486567 on 7p15, rs6465657 on 7q21, rs6983267 on 8q24, rs1447295 on 8q24, rs1571801 on 9q33, rs10993994 on 10q11, rs4962416 on 10q26, rs7931342 on 11q13, rs4430796 on 17q12, rs1859962 on 17q24.3, rs2735839 on 19q13, and rs5945619 on Xp11.22, but not rs2660753 on 3p12). EO PCa cases had a significantly greater cumulative number of risk alleles (mean 12.4) than iControlDB controls (mean 11.2; P = 2.1 × 10(-33)) or CGEMS cases (mean 11.9; P = 1.7 × 10(-5)). Notably, EO PCa cases had a higher frequency of the risk allele than CGEMS cases at 11 of 13 associated SNPs, with significant differences for five SNPs. EO PCa cases diagnosed at <50 (mean 12.8) also had significantly more risk alleles than those diagnosed at 50-55 years (mean 12.1; P = 0.0003).

CONCLUSIONS

These results demonstrate the potential for identifying PCa-associated genetic variants by focusing on the subgroup of men diagnosed with EO disease.

Germline mutations in HOXB13 and prostate-cancer risk

BACKGROUND

Family history is a significant risk factor for prostate cancer, although the molecular basis for this association is poorly understood. Linkage studies have implicated chromosome 17q21-22 as a possible location of a prostate-cancer susceptibility gene.

METHODS

We screened more than 200 genes in the 17q21-22 region by sequencing germline DNA from 94 unrelated patients with prostate cancer from families selected for linkage to the candidate region. We tested family members, additional case subjects, and control subjects to characterize the frequency of the identified mutations.

RESULTS

Probands from four families were discovered to have a rare but recurrent mutation (G84E) in HOXB13 (rs138213197), a homeobox transcription factor gene that is important in prostate development. All 18 men with prostate cancer and available DNA in these four families carried the mutation. The carrier rate of the G84E mutation was increased by a factor of approximately 20 in 5083 unrelated subjects of European descent who had prostate cancer, with the mutation found in 72 subjects (1.4%), as compared with 1 in 1401 control subjects (0.1%) (P=8.5x10(-7)). The mutation was significantly more common in men with early-onset, familial prostate cancer (3.1%) than in those with late-onset, nonfamilial prostate cancer (0.6%) (P=2.0x10(-6)).

CONCLUSIONS

The novel HOXB13 G84E variant is associated with a significantly increased risk of hereditary prostate cancer. Although the variant accounts for a small fraction of all prostate cancers, this finding has implications for prostate-cancer risk assessment and may provide new mechanistic insights into this common cancer. (Funded by the National Institutes of Health and others.).

Evidence for an association between prostate cancer and chromosome 8q24 and 10q11 genetic variants in African American men: the Flint Men's Health Study

BACKGROUND

Prostate cancer is the most commonly diagnosed non-skin cancer in men in the United States and the second leading cause of cancer-related mortality. African American men have substantially increased risk of both being diagnosed and dying from the disease. Recent genome-wide genetic association studies have identified a number of common single nucleotide genetic polymorphisms (SNPs) that are associated with prostate cancer in men of European descent. Only a small number of studies have evaluated the association between these genetic variants and prostate cancer in African Americans.

METHODS

We used logistic regression models to assess the association between prostate cancer in African American men and 24 SNPs from regions previously reported to be associated with prostate cancer in men of European descent.

RESULTS

We found nominal evidence (P < 0.05) for association between prostate cancer and three chromosome 8q24 (rs6983561, rs16901979, and rs7000448) and two 10q11 (rs7904463 and rs10740051) SNPs.

CONCLUSIONS

We confirm recent reports that 8q24 variants identified to be associated with prostate cancer in men of European descent are also associated with prostate cancer in African Americans. Our report is the first to find evidence of association between SNPs near MSMB and prostate cancer in African Americans. Of note, rs7000448 is in strong linkage disequilibrium with rs10761581 in NCOA4, a SNP that has been implicated to be independently associated, with respect to the widely reported SNP rs10993994 in the nearby gene MSMB, with prostate cancer in men of European descent.

Genetic variation in adiponectin (ADIPOQ) and the type 1 receptor (ADIPOR1), obesity and prostate cancer in African Americans

Background

Adiponectin is a protein derived from adipose tissue suspected to play an important role in prostate carcinogenesis. Variants in the adiponectin gene (ADIPOQ) and its type I receptor (ADIPOR1) have been recently linked to risk of both breast and colorectal cancer. Therefore, we set out to examine the relationship between polymorphisms in these genes, obesity and prostate cancer in study of African American men.

Methods

Ten single nucleotide polymorphisms (SNPs) in ADIPOQ and ADIPOR1 were genotyped in DNA samples from 131 African American prostate cancer cases and 344 controls participating in the Flint Men's Health Study. Logistic regression was then used to estimate their association with prostate cancer and obesity.

Results

While no significant associations were detected between any of the tested SNPs and prostate cancer, the rs1501299 SNP in ADIPOQ was significantly associated with body mass (p=0.03).

Conclusions

Genetic variation in ADIPOQ and ADIPOR1 did not predict risk of prostate cancer in this study of African American men. However, the rs1501299 SNP in ADIPOQ was associated with obesity. Further investigation is warranted to determine if racial differences exist in the influence of the adiponectin pathway on prostate cancer risk.

Absence of truncating BRIP1 mutations in chromosome 17q-linked hereditary prostate cancer families

Background:

In a genome-wide scan (GWS) of 175 multiplex prostate cancer (PCa) families from the University of Michigan Prostate Cancer Genetics Project (PCGP), linkage was observed to markers on chromosome 17q21–24, a region that includes two breast cancer susceptibility genes, BRCA1 and BRIP1. BRIP1 is a Fanconi anaemia gene (FANCJ) that interacts with the BRCT domain of BRCA1 and has a role in DNA damage repair. Protein truncating mutations in BRIP1 have been identified in hereditary breast and ovarian cancer families, and a recent report suggested that a recurrent truncating mutation (R798X) may have a role in PCa susceptibility.

Methods:

We examined the role of BRIP1 mutations in hereditary PCa through sequence analysis of 94 individuals from PCGP families showing linkage to 17q.

Results:

A total of 24 single-nucleotide polymorphisms, including 7 missense variants but no protein truncating mutations, were observed.

Conclusion:

The data presented here suggest that BRIP1 truncating mutations are uncommon in PCa cases and do not account for the linkage to chromosome 17q observed in our GWS. Additional investigation is needed to determine the significance, if any, of the observed BRIP1 missense variants in hereditary PCa.

Sequence variation in the mitochondrial gene cytochrome c oxidase subunit I and prostate cancer in African American men

BACKGROUND

Previous studies have found associations between mitochondrial DNA (mtDNA) mutations and several cancer types. Recently, we found that mutations in the mtDNA gene cytochrome c oxidase subunit 1 (COI) were both linked to and associated with prostate cancer (PCa) in Caucasian men. Here we examine the association between COI mutations and PCa in African American men.

METHODS

The entire COI gene was directly sequenced in 132 PCa cases and 135 controls from the Flint Men's Health Study, a community-based sample of African American men with and without PCa. Associations between all variants and PCa were evaluated.

RESULTS

We identified 102 COI single nucleotide polymorphisms (SNPs), including 15 missense variants. Overall, the presence of one or more COI missense variants was not significantly associated with PCa. Individually, two SNPs (T6221C and T7389C) were significantly associated with prostate cancer (P < 0.05) and in strong linkage disequilibrium with each other (r(2) > 0.6).

CONCLUSIONS

Of the two significantly associated SNPs, one is a synonymous substitution and the other is part of the African-specific mitochondrial haplogroup (L). Additional research will be needed to determine the clinical relevance of these associations in African populations.

Genome-wide linkage scan for prostate cancer susceptibility from the University of Michigan Prostate Cancer Genetics Project: suggestive evidence for linkage at 16q23

BACKGROUND

Prostate cancer linkage studies have been used to localize rare and presumably highly penetrant cancer susceptibility genes. Underlying genetic heterogeneity, as well as the high sporadic background of the disease, has resulted in many signals that are often not reproducible between research studies.

METHODS

We conducted a SNP-based genome wide linkage scan on 131 Caucasian prostate cancer families participating in the University of Michigan Prostate Cancer Genetics Project (PCGP).

RESULTS

The strongest evidence for linkage was detected at 16q23 (LOD = 2.70 at rs1079635). Prostate cancer linkage to the same region of 16q23 has been observed by others and the region contains several strong candidate genes including the known prostate cancer tumor suppressor genes ATBF1 and WWOX. This linkage signal was not detected in our prior linkage study on 175 PCGP families, illustrating the genetic heterogeneity underlying prostate cancer susceptibility.

CONCLUSIONS

Further linkage studies in combination with tumor analyses from linked families are in progress to identify the putative hereditary prostate cancer gene at 16q23.

Chromosome 17q12 variants contribute to risk of early-onset prostate cancer

In a recent genome-wide association study by Gudmundsson and colleagues, two prostate cancer susceptibility loci were identified on chromosome 17q. The first locus, at 17q12, was distinguished by two intronic single-nucleotide polymorphisms (SNPs) in the TCF2 gene (rs4430796 and rs7501939). The second locus was in a gene-poor region of 17q24, where the strongest evidence of association was for SNP rs1859962. To determine if these loci were also associated with hereditary prostate cancer, we genotyped them in a family-based association sample of 403 non-Hispanic white families, including 1,015 men with and without prostate cancer. SNPs rs4430796 and rs7501939, which were in strong linkage disequilibrium (r(2) = 0.68), showed the strongest evidence of prostate cancer association. Using a family-based association test, the A allele of SNP rs4430796 was overtransmitted to affected men (P = 0.006), with an odds ratio of 1.40 (95% confidence interval, 1.09-1.81) under an additive genetic model. Notably, rs4430796 was significantly associated with prostate cancer among men diagnosed at an early (<50 years) but not later age (P = 0.006 versus P = 0.118). Our results confirm the prostate cancer association with SNPs on chromosome 17q12 initially reported by Gudmundsson and colleagues. In addition, our results suggest that the increased risk associated with these SNPs is approximately doubled in individuals predisposed to develop early-onset disease. Importantly, these SNPs do not account for a significant portion of our prior prostate cancer linkage evidence on chromosome 17. Thus, there likely exist one or more additional independent prostate cancer susceptibility loci in this region.

Chromosome 8q24 markers: risk of early-onset and familial prostate cancer

Recent admixture mapping and linkage/association studies have implicated an approximately 1 Mb region on chromosome 8q24 in prostate cancer susceptibility. In a subsequent follow-up investigation, Haiman et al. (Nat Genet 2007;39:638-44) observed significant, independent associations between 7 markers within this region and sporadic prostate cancer risk in a multi-ethnic sample. To clarify the risk associated with hereditary prostate cancer, we tested for prostate cancer association with 6 of these 7 markers in a sample of 1,015 non-Hispanic white men with and without prostate cancer from 403 familial and early-onset prostate cancer families. Single nucleotide polymorphisms (SNPs) rs6983561 and rs6983267 showed the strongest evidence of prostate cancer association. Using a family-based association test, the minor ("C") allele of rs6983561 and the major ("G") allele of rs6983267 were preferentially transmitted to affected men (p < 0.05), with estimated odds ratios (ORs) of 2.26 (95% confidence interval of 1.06-4.83) and 1.30 (95% confidence interval of 0.99-1.71), respectively, for an additive model. Notably, rs6983561 was significantly associated with prostate cancer among men diagnosed at an early (<50 years) but not later age (p = 0.03 versus p = 0.21). Similarly, the association with rs6983267 was (not) statistically significant among men with(out) clinically aggressive disease (p = 0.007 versus p = 0.34). Our results confirm the association of prostate cancer with several of the SNPs on chromosome 8q24 initially reported by Haiman et al. In addition, our results suggest that the increased risk associated with these SNPs is approximately doubled in individuals predisposed to develop early onset or clinically aggressive disease.

Sequence variation in alpha-methylacyl-CoA racemase and risk of early-onset and familial prostate cancer

BACKGROUND

Expression of the alpha-methylacyl-CoA racemase (AMACR) gene has been established as a sensitive and specific biomarker for the diagnosis of prostate cancer. An initial study has also suggested that the risk of familial (but not sporadic) prostate cancer may be associated with germline variation in the AMACR gene.

METHODS

In a study of brothers discordant for the diagnosis of prostate cancer (including 449 affected and 394 unaffected men) from 332 familial and early-onset prostate cancer families, we used conditional logistic regression and family-based association tests to investigate the association between prostate cancer and five single nucleotide polymorphisms (SNPs) tagging common haplotype variation within the coding and regulatory regions of AMACR.

RESULTS

The strongest evidence for prostate cancer association was for SNP rs3195676, with an estimated odds ratio of 0.58 (95% confidence interval = 0.38-0.90; P = 0.01 for a recessive model). This non-synonymous SNP (nsSNP) results in a methionine-to-valine substitution at codon 9 (M9V) in exon 2 of the AMACR gene. Three additional nsSNPs showed suggestive evidence for prostate cancer association (P < or = 0.10).

CONCLUSIONS

Our results confirm an initial report of association between the AMACR gene and the risk of familial prostate cancer. These findings emphasize the value of studying early-onset and familial prostate cancer when attempting to identify genetic variation associated with prostate cancer.

Common variation in the BRCA1 gene and prostate cancer risk

Rare inactivating mutations in the BRCA1 gene seem to play a limited role in prostate cancer. To our knowledge, however, no study has comprehensively assessed the role of other BRCA1 sequence variations (e.g., missense mutations) in prostate cancer. In a study of 817 men with and without prostate cancer from 323 familial and early-onset prostate cancer families, we used family-based association tests and conditional logistic regression to investigate the association between prostate cancer and single nucleotide polymorphisms (SNPs) tagging common haplotype variation in a 200-kb region surrounding (and including) the BRCA1 gene. We also used the Genotype-Identity-by-Descent Sharing Test to determine whether our most strongly associated SNP could account for prostate cancer linkage to chromosome 17q21 in a sample of 154 families from our previous genome-wide linkage study. The strongest evidence for prostate cancer association was for a glutamine-to-arginine substitution at codon 356 (Gln(356)Arg) in exon 11 of the BRCA1 gene. The minor (Arg) allele was preferentially transmitted to affected men (P = 0.005 for a dominant model), with an estimated odds ratio of 2.25 (95% confidence interval, 1.21-4.20). Notably, BRCA1 Gln(356)Arg is not in strong linkage disequilibrium with other BRCA1 coding SNPs or any known HapMap SNP on chromosome 17. In addition, Genotype-Identity-by-Descent Sharing Test results suggest that Gln(356)Arg accounts (in part) for our prior evidence of prostate cancer linkage to chromosome 17q21 (P = 0.022). Thus, we have identified a common, nonsynonymous substitution in the BRCA1 gene that is associated with and linked to prostate cancer.

Association between Germline Variation in the FHIT Gene and Prostate Cancer in Caucasians and African Americans

Many studies have established that loss of heterozygosity and/or altered expression of the fragile histidine triad (FHIT) gene is a common event in a number of tumor types including prostate carcinoma. Encompassing the most active fragile site in the human genome, FRA3B, FHIT has become the model fragile site-associated tumor suppressor gene. In a recent study, linkage and association between germline genetic variation in FHIT (specifically single nucleotide polymorphism rs760317) and prostate cancer were reported. We sought to confirm this finding in two independent samples: (a) a family-based sample of 817 men with (n = 434) and without (n = 383) prostate cancer from 323 Caucasian families, and (b) a community-based case-control sample of African American men with (n = 133) and without (n = 342) prostate cancer. Using a family-based association test, rs760317 was associated with prostate cancer in Caucasians (P = 0.031), with a reduction in the risk of prostate cancer among carriers of the minor allele (odds ratio, 0.66; 95% confidence interval, 0.42-1.04; P = 0.074). African American carriers experienced a similar risk reduction (odds ratio, 0.63; 95% confidence interval, 0.42-0.96; P = 0.032). These results are remarkably consistent across ethnic samples but are in opposition to results from the original study, which showed an association between the minor allele of rs760317 and an increased risk of prostate cancer. Taken together, the consistently significant but flipped association between single nucleotide polymorphism rs760317 and prostate cancer in three independent samples suggests that rs760317 may be in linkage disequilibrium with one or more prostate cancer susceptibility variants in or near FHIT.

INSPstI polymorphism and prostate cancer in African-American men

BACKGROUND

Both prostate cancer and diabetes mellitus are common diseases in African-American men. High insulin levels and insulin resistance have been implicated in prostate cancer development, which has prompted a recent investigation of a possible role for germline variation in the insulin gene (INS) and prostate cancer risk.

METHODS

Four hundred sixty-six African-American men with and without prostate cancer from the Flint Men's Health Study were typed for the INS Pst1 genotype using restriction digest and direct sequencing. An association between the Pst1 genotype and prostate cancer was examined using crude and age-adjusted logistic regression models.

RESULTS

African-American men who were homozygous for the INS PstI CC genotype were 1.59 times more likely to be diagnosed with prostate cancer compared to men with the TT or TC genotypes (95% CI = 0.93-2.72). The association appeared stronger among diabetics compared to non-diabetics; however this observation was not statistically significant.

CONCLUSIONS

Our study, taken together with the report of Ho et al., suggests that the INS Pst1 CC genotype is associated with prostate cancer risk in African-American men. Germline variation in the INS gene should be more fully explored in multiethnic studies to elucidate the molecular variant(s) associated with prostate carcinogenesis.

Identifying Susceptibility Genes for Prostate Cancer--A Family-Based Association Study of Polymorphisms in CYP17, CYP19, CYP11A1, and LH-

Polymorphisms in genes that code for enzymes or hormones involved in the synthesis and metabolism of androgens are compelling biological candidates for prostate cancer. Four such genes, CYP17, CYP19, CYP11A1, and LH-beta, are involved in the synthesis and conversion of testosterone to dihydrotestosterone and estradiol. In a study of 715 men with and without prostate cancer from 266 familial and early-onset prostate cancer families, we examined the association between prostate cancer susceptibility and common single-nucleotide polymorphisms in each of these four candidate genes. Family-based association tests revealed a significant association between prostate cancer and a common single-nucleotide polymorphism in CYP17 (P=0.004), with preferential transmission of the minor allele to unaffected men. Conditional logistic regression analysis of 461 discordant sibling pairs from these same families reaffirmed the association between the presence of the minor allele in CYP17 and prostate cancer risk (odds ratio, 0.51; 95% confidence interval, 0.28-0.92). These findings suggest that variation in or around CYP17 predicts susceptibility to prostate cancer. Family-based association tests may be especially valuable in studies of genetic variation and prostate cancer risk because this approach minimizes confounding due to population substructure, which is of particular concern for prostate cancer given the tremendous variation in the worldwide incidence of this disease.

Truncating BRCA1 Mutations Are Uncommon in a Cohort of Hereditary Prostate Cancer Families with Evidence of Linkage to 17q Markers

PURPOSE

A genome-wide scan of 175 hereditary prostate cancer families from the University of Michigan Prostate Cancer Genetics Project provided evidence of prostate cancer linkage to 17q markers near the BRCA1 gene. To examine the possibility that germ-line BRCA1 mutations were associated with hereditary prostate cancer, individuals from 93 families with evidence of linkage to chromosome 17q were screened for germ-line BRCA1 mutations.

EXPERIMENTAL DESIGN

One individual from each of the 93 families, the majority with three or more cases of prostate cancer, were screened for BRCA1 mutations with denaturing high-performance liquid chromatography (HPLC). Fragments exhibiting denaturing HPLC variant patterns were additionally analyzed by direct sequencing.

RESULTS

Sixty-five of the individuals selected for sequencing from 65 unrelated families were determined to have wild-type BRCA1 sequence by denaturing HPLC. One individual from a family with both prostate and ovarian cancer was found to have a truncating BRCA1 mutation (3829delT). An additional 27 germ-line variants were identified, including 15 missense variants.

CONCLUSIONS

These sequencing results suggest that BRCA1 truncating mutations do not account for the linkage evidence on chromosome 17 observed in University of Michigan Prostate Cancer Genetics Project families. A recently completed combined genome scan has also detected linkage to 17q22, and studies are ongoing to identify the relevant prostate cancer susceptibility gene in this region.

Use of complementary and alternative medicine in men with family history of prostate cancer: a pilot study

OBJECTIVES

To describe the use of complementary and alternative medicines (CAMs) among men with a family history of prostate cancer and to evaluate the relationship between selected sociodemographic and behavioral characteristics and the use of CAMs.

METHODS

Unaffected brothers of men diagnosed with prostate cancer were asked to participate in a short computer-assisted telephone interview. The survey focused primarily on the use of different vitamins, herbal supplements, and medications, some of which are marketed for prostate health or prostate cancer prevention.

RESULTS

A total of 111 men completed the survey, representing 66% of eligible study subjects. Of the 111 men, 61 (55%) reported currently taking some form of CAM, with 30% taking a vitamin or supplement purported to have prostate-specific benefits. The prevalence of CAM use generally increased with increasing age; however, men who were younger than their affected brother at the time of the diagnosis of prostate cancer were more likely to use CAMs than were older brothers.

CONCLUSIONS

Most men with a family history of prostate cancer take vitamins and supplements, some of which are believed to prevent future cancer occurrence. The results of this study and others provide some insight into the determinants of potentially beneficial health behaviors in high-risk individuals.

Risk perception and concern among brothers of men with prostate carcinoma

BACKGROUND

It is important for clinicians, researchers, and others who shape public health policy to understand the demographic correlates and psychologic factors that drive health behaviors, such as screening for early detection of cancer, particularly among individuals at high risk for developing the disease.

METHODS

One-hundred eleven men whose brothers were diagnosed with prostate carcinoma completed a computer-assisted telephone interview aimed to assess their perception of absolute risk and concern about developing prostate carcinoma over the next 10 years and across their lifetime. Comparisons were made between selected demographic, behavioral, family pedigree characteristics, and measures of perceived risk and concern.

RESULTS

The majority of men perceived their personal risk of developing prostate carcinoma to be > or =50%. Men who at the time of the interview were younger than their affected brother were significantly more concerned about prostate carcinoma and perceived their risk to be higher than men who were older than their brother. Estimates of personal risk and concern were also uniformly higher among men with more than one first-degree relative affected with prostate carcinoma compared to men with only one affected first-degree relative. Risk perception and concern about an impending prostate carcinoma diagnosis were associated with the use of supplements marketed for prostate health.

CONCLUSIONS

The findings indicated that birth order in relation to a brother diagnosed with prostate carcinoma is significantly associated with risk perception and concern in unaffected family members. These results highlight the need for further study of the familial dynamics and characteristics that drive health behaviors and stress importance of public health education to inform men of personal risk assessment as well as the risks and benefits of screening. These studies ultimately can contribute to the success of strategies for the primary prevention and early detection of cancer.