Identification of germline MLH1 alterations in familial prostate cancer

Several linkage and loss of heterozygosity (LOH) analyses suggest that the region 3p21-p26, which is a chromosomal location of MLH1, could harbour a susceptibility gene for prostate cancer (PRCA). Furthermore, in a recent candidate single nucleotide polymorphism (SNP) analysis the I219V variation of the MLH1 gene was associated with PRCA. Microsatellite instability (MSI) and germ-line MLH1 mutations were originally demonstrated in hereditary non-polyposis colorectal cancer (HNPCC) but MSI and loss of MLH1 function have also been detected in PRCA. To assess the contribution of MLH1 germline mutations to the development of PRCA in Finland different approaches were used. First, the samples from 11 PRCA-colon cancer patients were screened for MLH1, MSH2 and MSH6 protein expression by immunohistochemistry (IHC). IHC revealed one patient with a putative MLH1 aberration and sequencing of this sample revealed five sequence variants including two missense variants P434L and I219V. Second, the samples from Finnish hereditary prostate cancer (HPC) families were used for the screening of MLH1 mutations which produced twelve MLH1 sequence variants including two missense mutations, I219V, as in the PRCA-colon cancer patient, and V647M. P434L and V647 were both novel, rare variants. Carrier frequencies of the I219V mutation were compared between hereditary prostate cancer (HPC) patients, unselected PRCA cases, patients with benign prostate hyperplasia and controls, but no differences between the sample groups were found. P434L was not present in this study population and V647M was a very rare variant found only in one HPC family. According to the present results, MLH1 does not have a major role in PRCA causation in Finland.     

ELAC2/HPC2 involvement in hereditary and sporadic prostate cancer

The ELAC2/HPC2 gene at 17p11 is the first candidate gene identified for human prostate cancer (PRCA) based on linkage analysis and positional cloning (S. V.Tavtigian et al. Nat. Genet., 27:172-180, 2001). A truncating mutation was found in one hereditary prostate cancer (HPC) family, whereas two missense variants, Ser217Leu and Ala541Thr, were reported to be associated with increased PRCA risk in the general population. Here, we screened for mutations of the ELAC2/HPC2 gene in 66 Finnish HPC families. Several sequence variants, including a new exonic variant (Glu622Val) were found, but none of the mutations were truncating. We then analyzed the frequency of the three found missense variants in 1365 individuals, including hereditary (n = 107) and unselected (n = 467) PRCA, benign prostatic hyperplasia (n = 223), and population controls (568 healthy male blood donors). Ser217Leu and Ala541Thr variants carried no significantly elevated risk for HPC or PRCA, although the latter variant was associated with benign prostatic hyperplasia. The previously undescribed Glu622Val variant had a 1.0% population prevalence, but a significantly higher frequency in PRCA cases (3.0% odds ratio, 2.94; 95% confidence interval, 1.05-8.23). We conclude that ELAC2/HPC2 truncating mutations are rare in HPC, but that rare variants of the ELAC2/HPC2 require additional study as risk factors for PRCA in the general population.     

Genetic analysis of the RNASEL gene in hereditary, familial, and sporadic prostate cancer.

PURPOSE: The RNASEL gene has been proposed as a candidate gene for the HPC1 locus through a positional cloning and candidate gene approach. Cosegregation between the truncating mutation E265X and disease in a hereditary prostate cancer (HPC) family and association between prostate cancer risk and the common missense variant R462Q has been reported. To additionally evaluate the possible role of RNASEL in susceptibility to prostate cancer risk, we performed a comprehensive genetic analysis of sequence variants in RNASEL in the Swedish population. EXPERIMENTAL DESIGN: Using 1624 prostate cancer cases and 801 unaffected controls, the truncating mutation E265X and five common sequence variants, including the two missense mutations R462Q and D541E, were evaluated for association between genotypes/haplotypes and prostate cancer risk. RESULTS: The prevalence of E265X carriers among unaffected controls and prostate cancer patients was almost identical (1.9 and 1.8% in controls and cases, respectively), and evidence for segregation of E265X with disease was not observed within any HPC family. Overall, the analyses of common sequence variants provided limited evidence for association with prostate cancer risk. We found a marginally significant inverse association between the missense mutation D541E and sporadic prostate cancer risk (odds ratio, 0.77; 95% confidence interval, 0.59-1.00) and reduced risk of prostate cancer in carriers of two different haplotypes being completely discordant. CONCLUSIONS: Considering the high quality in genotyping and the size of this study, these results provide solid evidence against a major role of RNASEL in prostate cancer etiology in Sweden.     

MSR1 variants and the risks of prostate cancer and benign prostatic hyperplasia: a population-based study in China

Data from epidemiologic and twin studies suggest an important role of genetic susceptibility in prostate cancer. Variants of the macrophage scavenger receptor 1 (MSR1) gene have been linked to both hereditary and sporadic prostate cancer, although the evidence is inconclusive. Most studies have been conducted on Caucasians. The role of MSR1 in prostate cancer development among Asians, for whom rates of prostate cancer are low but rising rapidly, is unclear. To evaluate further the relationship between MSR1 variants and prostate cancer risk, we sequenced all the 11 MSR1 exons, exon-intron junctions, promoter regions, as well as 5' and 3' untranslated regions (UTRs) in 86 individuals from Shanghai, China. We identified a total of 21 sequence variants, including three novel variants that have not been reported previously. To balance genotyping cost and the capacity to capture sufficient genetic variation, we genotyped four haplotype-tagging variants (P275A, INDEL7, P346P and 3' UTR 70006), which capture 85% of the genetic variation in MSR1 in this population. These four variants, plus two other variants (PRO3 and INDEL1) that have been linked to prostate cancer risk in the previous studies, were typed for all study subjects, which included 130 prostate cancer cases, 130 patients with benign prostatic hyperplasia and 150 controls randomly selected from the population. Three of the six variants were associated with prostate cancer. Men with a P346P (a novel variant) G allele (AG + GG) had a significantly reduced risk of total prostate cancer [odds ratio = 0.47, 95% confidence interval (CI) 0.23-0.96], whereas those with a P275A G allele had a 37% reduced risk of prostate cancer (95% CI 0.39-1.02), with more pronounced reduction in risk seen for localized cancer cases (odds ratio = 0.25, 95% CI 0.12-0.52; P = 0.001). In addition, men with the INDEL7 variant had a 67% reduced risk of localized cancer (95% CI 0.16-0.68). Based on the four tagging variants, we inferred four major haplotypes that accounted for >90% of the haplotype variation in this population. The haplotype frequencies were significantly different between localized prostate cancer cases and controls, with a global P value of 0.004, and the haplotype containing the minor alleles of the P275A and INDEL7 variants was associated with a significantly reduced risk of localized prostate cancer (odds ratio = 0.28, 95% CI 0.13-0.59), relative to the most common haplotype. These results, although modest and confined mainly to localized prostate cancer, suggest that MSR1 polymorphisms may play a role in prostate cancer etiology in Chinese men. The role of MSR1 warrants further investigation in larger studies and other populations.     

Association of susceptibility alleles in ELAC2/HPC2, RNASEL/HPC1, and MSR1 with prostate cancer severity in European American and African American men.

Reported associations of ELAC2/HPC2, RNASEL/HPC1, and MSR1 with prostate cancer have been inconsistent and understudied in African Americans. We evaluated the role of 16 sequence variants in these genes with prostate cancer using 888 European American and 131 African American cases, and 473 European American and 163 African American, controls. We observed significant differences in ELAC2, RNASEL, and MSR1 allele frequencies by race. However, we did not observe significant associations between prostate cancer and any variants examined for both races combined. Associations were observed when stratified by race, family history, or disease severity. European American men homozygous for MSR1 IVS7delTTA had an elevated risk for localized stage [odds ratio, (OR), 3.5; 95% confidence interval (95% CI), 1.4-6.9], low-grade (OR, 3.2; 95% CI, 1.4-7.3) disease overall, and with low-grade (OR, 2.9; 95% CI, 1.2-7.2) or late-stage disease (OR, 5.2; 95% CI, 1.1-25.7) in family history-negative African Americans. MSR1 Arg293X was associated with family history-negative high-grade disease (OR, 4.0; 95% CI, 1.1-14.1) in European Americans. RNASEL Arg462Gln was associated with low-grade (OR, 1.5; 95% CI, 1.04-2.2) and early-stage (OR, 1.5; 95% CI, 1.02-2.1) disease in family history-negative European Americans. In family history-positive individuals, Arg462Gln was inversely associated with low-grade (OR, 0.43; 95% CI, 0.21-0.88) and low-stage (OR, 0.46; 95% CI, 0.22-0.95) disease. In African Americans, Arg462Gln was associated with positive family history high-stage disease (OR, 14.8; 95% CI, 1.6-135.7). Meta-analyses revealed significant associations of prostate cancer with MSR1 IVS7delTTA, -14,742 A>G, and Arg293X in European Americans; Asp174Tyr in African Americans; RNASEL Arg462Gln in European American's overall and in family history-negative disease; and Glu265X in family history-positive European Americans. Therefore, MSR1 and RNASEL may play a role in prostate cancer progression and severity.     

A polymorphism in the CDKN1B gene is associated with increased risk of hereditary prostate cancer

The loss of cell cycle control is believed to be an important mechanism in the promotion of carcinogenesis. CDKN1B (p27) belongs to the Cip/Kip family and functions as an important cell cycle gatekeeper. Several lines of evidence from clinical studies and laboratory experiments demonstrate that CDKN1B is an important tumor suppressor gene in prostate cancer etiology. In addition, a case-control study has shown that the 326T/G (V109G) polymorphism in CDKN1B is associated with advanced prostate cancer. In light of the evidence for linkage between the chromosomal location of the CDKN1B gene (12p13) and prostate cancer susceptibility in several hereditary prostate cancer (HPC) populations, we hypothesized that sequence variants of CDKN1B play a role in HPC. To test this hypothesis, we first resequenced this gene in 96 HPC probands to identify germ-line mutations and sequence variants. We then genotyped the identified sequence variants among all family members of 188 HPC families and tested for their cosegregation with prostate cancer. In total, 10 sequence variants were identified, including three nonsynonymous changes. A family-based test, which is free from the effects of population stratification, revealed a significant association between single nucleotide polymorphism (SNP) -79C/T and prostate cancer (with a nominal P of 0.0005). The C allele of -79C/T was overtransmitted from parents to their affected offspring. Evidence for this association was primarily contributed by affected offspring whose age at diagnosis was <65 years. Together with the previous association study in a sporadic prostate cancer population, our new findings additionally suggest that germ-line variants of this gene play a role in prostate cancer susceptibility.     

Sequence variants of alpha-methylacyl-CoA racemase are associated with prostate cancer risk

The enzyme alpha-methylacyl-CoA racemase (AMACR) plays an important role in peroxisomal beta-oxidation of branched-chain fatty acid and therefore is relevant to carcinogenesis. The involvement of AMACR in prostate cancer (CaP) is implicated by the recent observation that expression of AMACR is consistently and extensively up-regulated in CaP. This observation is of particular interest, given previous findings from epidemiological studies that red meat and dairy products, major sources of branched-chain fatty acid, are associated with CaP risk and from linkage studies that the AMACR gene region at 5p13 is linked to a CaP susceptibility gene. In this study, we hypothesize that sequence variants in AMACR may alter the risk for CaP. To test this hypothesis, we sequenced all five exons, exon-intron junctions, the promoter region, and 3'-untranslated region of AMACR in germ-line DNA samples of 96 probands from hereditary CaP (HPC) families. Seventeen sequence variants, including five novel (R118Q, V185A, P238S, Q239H, and L250R) and five known (M9V, S52P, D175G, S201L, and K277E) missense changes, were identified. Six of these variants are at conserved residues among the rat and mouse AMACR. Eleven of these single nucleotide polymorphisms were genotyped in a total of 159 HPC probands, 245 sporadic cases, and 211 unaffected controls to assess their association with CaP risk. Significantly different genotype frequencies between HPC probands and unaffected controls were found for several missense changes, including M9V (P = 0.03), G1175D (P = 0.02), S291L (P = 0.02), and K277E (P = 0.02). Haplotype analysis provided stronger evidence for association (P = 0.001). Furthermore, the AMACR sequence variants strongly cosegregate with CaP in HPC families (log of odds = 3.78; P = 0.00006), especially in the subset of families whose probands carry the "A-A" haplotype of M9V and D175G (log of odds = 4.34; P = 0.000008). These results suggest that sequence variants in AMACR may be associated with CaP risk.     

Germline mutations in E-cadherin do not explain association of hereditary prostate cancer, gastric cancer and breast cancer

Somatic mutations in the E-cadherin (CDH1) gene have frequently been reported in cases with diffuse gastric and lobular breast cancers. Recently, germline mutations have been identified in families with diffuse gastric cancers. In families with hereditary prostate cancer (HPC), a significant association of prostate cancer, gastric and/or breast cancer has been observed in epidemiological studies. The aim of this study was to investigate if germline mutations in CDH1 could explain the risk for cancer in HPC families with an excess of gastric and breast cancer. In total, 17 members from 13 HPC families and 3 members from 3 families with hereditary gastric cancer (HGC) were screened for germline CDH1 sequence alterations using PCR/Denaturing HPLC for initial screening of nucleotide variants followed by confirmatory direct sequencing analysis. The frequency of identified novel germline mutations were tested for in 136 cases with hereditary prostate cancer and 215 cases of sporadic prostate cancer with 422 age matched controls in an allelic discrimination assay. In total, 8 sequence variants were detected in 20 samples tested. In the HPC families, we found 2 missense mutations, A592T in exon 12 and a novel D777N in exon 15 and a mutation in intron 5, 687+92T>A. A previously known polymorphism in exon 13 and 3 sequence variations in introns and untranslated regions were also found, of which the significance is unknown. In HGC-023 with early onset diffuse gastric cancer a truncating mutation, R335X, was identified in exon 7. None of the missense mutations or 687+92T>A were found in the extended HPC material or in the sporadic prostate cancer cases with age-matched controls in the allelic discrimination assay. We found several germline mutations of unknown clinical significance in the CDH1 gene that probably do not explain the association of prostate, gastric and/or breast cancers in the HPC-families. Two missense mutations and a mutation in intron 5 were identified that do not influence the risk of hereditary or sporadic prostate cancer in general and are considered to be pedigree specific. In a family with hereditary gastric cancer of the diffuse type, we identified the first truncating germline mutation in a Scandinavian family.     

Linkage and association of CYP17 gene in hereditary and sporadic prostate cancer.

Androgens are essential for prostate development, growth and maintenance and the association between androgen levels and prostate cancer is well established. Since the CYP17 gene encodes the enzyme cytochrome P450c17alpha, which mediates 17alpha-hydroxylase and 17,20-lyase activities in the androgen biosynthesis pathway, sequence variations in the gene and association with increased risk to prostate cancer has been studied. In particular, several groups have studied the association between a polymorphism in the 5' promoter region and prostate cancer using a population-based association approach. However, the results from these studies were inconclusive. To further study this polymorphism and its possible role in hereditary prostate cancer (HPC), we performed a genetic linkage analysis and family-based association analysis in 159 families, each of which contains at least 3 first-degree relatives with prostate cancer. In addition, we performed a population-based association analysis to compare the risk of this polymorphism to hereditary and sporadic prostate cancer in 159 HPC probands, 249 sporadic prostate cancer patients and 211 unaffected control subjects. Evidence for linkage at the CYP17 gene region was found in the total 159 HPC families (LOD = 1.3, p = 0.01, at marker D10S222). However, family-based association tests did not provide evidence for overtransmission of either allele of the CYP17 polymorphism to affected individuals in the HPC families. The allele and genotype frequencies of the polymorphism were not statistically different among the HPC probands, sporadic cases and unaffected control subjects. In conclusion, our results suggest that the CYP17 gene or other genes in the region may increase the susceptibility to prostate cancer in men; however, the polymorphism in the 5' promoter region has a minor role if any in increasing prostate cancer susceptibility in our study sample.     

Macrophage scavenger receptor 1 999C>T (R293X) mutation and risk of prostate cancer.

BACKGROUND: Variants in the gene encoding the macrophage scavenger receptor 1 (MSR1(4)) protein have been identified in men with prostate cancer, and several small studies have suggested that the 999C>T (R293X) protein-truncating mutation may be associated with an increased risk for this disease. METHODS: Using large case-control, cohort, and prostate cancer family studies conducted in several Western countries, we tested for the 999C>T mutation in 2,943 men with invasive prostate carcinoma, including 401 males from multiple-case families, 1,982 cases unselected for age, and 575 men diagnosed before the age of 56 years, and in 2,870 male controls. Risk ratios were estimated by unconditional logistic regression adjusting for country and by a modified segregation analysis. A meta-analysis was conducted pooling our data with published data. RESULTS: The prevalence of MSR1*999C>T mutation carriers was 0.027 (SE, 0.003) in cases and 0.022 (SE, 0.002) in controls, and did not differ by country, ethnicity, or source. The adjusted risk ratio for prostate cancer associated with being a 999C>T carrier was 1.31 [95% confidence interval (CI), 0.93-1.84; P = 0.16]. The modified segregation analysis estimated the risk ratio to be 1.20 (95% CI, 0.87-1.66; P = 0.16). The risk ratio estimated from the meta-analysis was 1.34 (95% CI, 0.94-1.89; P = 0.10). CONCLUSION: Our large-scale analysis of case and controls from several countries found no evidence that the 999C>T mutation is associated with increased risk of prostate cancer. The meta-analysis suggests it is unlikely that this mutation confers more than a 2-fold increased risk.     

Germ-line mutations of the macrophage scavenger receptor 1 gene: association with prostate cancer risk in African-American men

Both rare germ-line mutations and common sequence variants of the macrophage scavenger receptor 1 (MSR1) gene have recently been implicated as potential prostate cancer susceptibility factors. However, existing studies are limited by the referral-based nature of samples and a paucity of African-American participants. In this context, we evaluated the association of germ-line mutations and common MSR1 sequence variants with prostate cancer risk in a case control study of a community-based sample of 134 African-American men with prostate cancer and 340 unaffected controls. In our sample, the rare Asp174Tyr missense change was identified nearly twice as frequently in men with prostate cancer (6.8%) compared with unaffected controls (3.6%; P = 0.14). Moreover, significantly different allele frequencies between cases and controls were observed for one of the sequence variants, IVS5-59 (P = 0.02). Taken together, our results provide some additional support for the hypothesis that selected, rare MSR1 mutations are associated with increased prostate cancer susceptibility among African-American men.     

Mutation screening and association study of RNASEL as a prostate cancer susceptibility gene

To date, germline mutations have been found in three candidate genes for hereditary prostate cancer: ELAC2 at 17p11, RNASEL at 1q25 and MSR1 at 8p22. RNASEL, encoding the 2',5'-oligoadenylate-dependant RNase L, seems to have rare mutations in different ethnicities, such as M1I in Afro-Americans, E265X in men of European descent and 471delAAAG in Ashkenazi Jews. In order to evaluate the relevance of RNASEL in the German population, we sequenced its open reading frame to determine the spectrum and frequency of germline mutations. The screen included 303 affected men from 136 Caucasian families, of which 45 met the criteria for hereditary prostate cancer. Variants were analysed using a family-based association test, and genotyped in an additional 227 sporadic prostate cancer patients and 207 controls. We identified only two sib pairs (1.4% of our families) cosegregating conspicuous RNASEL variants with prostate cancer: the nonsense mutation E265X, and a new amino-acid substitution (R400P) of unknown functional relevance. Both alleles were also found at low frequencies (1.4 and 0.5%, respectively) in controls. No significant association of polymorphisms (I97L, R462Q and D541E) was observed, neither in case-control analyses nor by family-based association tests. In contrast to previous reports, our study does not suggest that common variants (i.e. R462Q) modify disease risk. Our results are not consistent with a high penetrance of deleterious RNASEL mutations. Due to the low frequency of germline mutations present in our sample, RNASEL does not have a significant impact on prostate cancer susceptibility in the German population.     

CHEK2 variants associate with hereditary prostate cancer

Recently, variants in CHEK2 gene were shown to associate with sporadic prostate cancer in the USA. In the present study from Finland, we found that the frequency of 1100delC, a truncating variant that abrogates the kinase activity, was significantly elevated among 120 patients with hereditary prostate cancer (HPC) (four out of 120 (3.3%); odds ratio 8.24; 95% confidence interval 1.49-45.54; P=0.02) compared to 480 population controls. Suggestive evidence of segregation between the 1100delC mutation and prostate cancer was seen in all positive families. In addition, I157T variant had significantly higher frequency among HPC patients (13 out of 120 (10.8%); odds ratio 2.12; 95% confidence interval 1.06-4.27; P=0.04) than the frequency 5.4% seen in the population controls. The results suggest that CHEK2 variants are low-penetrance prostate cancer predisposition alleles that contribute significantly to familial clustering of prostate cancer at the population level.     

Germline mutations in the BRCA2 gene and susceptibility to hereditary prostate cancer.

PURPOSE: Several epidemiologic studies have reported that carriers of germline mutations in the BRCA2 gene have an increased risk of prostate cancer, with the highest risk observed in men diagnosed at earlier ages. However, studies of the contribution of BRCA2 mutations to the etiology of hereditary prostate cancer (HPC) have been inconsistent. EXPERIMENTAL DESIGN: To further address this issue, 266 subjects from 194 HPC families participating in the Seattle-based Prostate Cancer Genetic Research Study were screened for BRCA2 mutations by sequencing the coding regions, intron-exon boundaries, and suspected regulatory elements of this gene. Of selected HPC families, 32 had multiple breast or ovarian cancer cases, 16 were Jewish, 8 had a pancreatic cancer case, and 138 had at least one affected man diagnosed with prostate cancer at an early age (<60 years). RESULTS: No disease-associated protein truncating BRCA2 mutations were found in 266 subjects from HPC families. There were 61 DNA sequence variants, of which 31 (50.8%) changed the predicted amino acids. No associations were found between these missense changes and family characteristics. Among affected men with prostate cancer, there were no statistically significant differences between the genotype frequencies of DNA variants with a minor allele frequency of 1% or higher and between the strata defined by median age at diagnosis or by clinical features. CONCLUSION: No evidence was found in this study for an association between BRCA2 mutations and susceptibility to HPC in men selected from high-risk families.     

Effects of RNase L mutations associated with prostate cancer on apoptosis induced by 2',5'-oligoadenylates

The RNASEL gene, a strong candidate for the hereditary prostate cancer 1 allele (HPC1), encodes a single-stranded specific endoribonuclease involved in the antiviral actions of IFNs. RNase L is activated enzymatically after binding to unusual 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A). Biostable phosphorothioate analogues of 2-5A were synthesized chemically and used to study the effects of naturally occurring mutations and polymorphisms in RNASEL. The 2-5A analogues induced RNase L activity and caused apoptosis in cultures of late-stage, metastatic human prostate cancer cell lines DU145, PC3, and LNCaP. However, DU145 and PC3 cells were more sensitive to 2-5A than LNCaP cells, which are heterozygous for an inactivating deletion mutation in RNase L. The RNase activities of missense variants of human RNase L were compared after expression in a mouse RNase L(-/-) cell line. Several variants (G59S, I97L, I220V, G296V, S322F, Y529C, and D541E) produced similar levels of RNase L activity as wild-type enzyme. In contrast, the R462Q variant, previously implicated in up to 13% of unselected prostate cancer cases, bound 2-5A at wild-type levels but had a 3-fold decrease in RNase activity. The deficiency in RNase L(R462Q) activity was correlated with a reduction in its ability to dimerize into a catalytically active form. Furthermore, RNase L(R462Q) was deficient in causing apoptosis in response to 2-5A consistent with its possible role in prostate cancer development. Our findings support the notion that RNASEL mutations and some variants allow tumor cells to escape a potent apoptotic pathway.     

Germ-line mutation of NKX3.1 cosegregates with hereditary prostate cancer and alters the homeodomain structure and function

NKX3.1, a gene mapped to 8p21, is a member of the NK class of homeodomain proteins and is expressed primarily in the prostate. NKX3.1 exerts a growth-suppressive and differentiating effect on prostate epithelial cells. Because of its known functions and its location within a chromosomal region where evidence for prostate cancer linkage and somatic loss of heterozygosity is found, we hypothesize that sequence variants in the NKX3.1 gene increase prostate cancer risk. To address this, we first resequenced the NKX3.1 gene in 159 probands of hereditary prostate cancer families recruited at Johns Hopkins Hospital; each family has at least three first-degree relatives affected with prostate cancer. Twenty-one germ-line variants were identified in this analysis, including one previously described common nonsynonymous change (R52C), two novel rare nonsynonymous changes (A17T and T164A), and a novel common 18-bp deletion in the promoter. Overall, the germ-line variants were significantly linked to prostate cancer, with a peak heterogeneity logarithm of odds of 2.04 (P = 0.002) at the NKX3.1 gene. The rare nonsynonymous change, T164A, located in the homeobox domain of the gene, segregated with prostate cancer in a family with three affected brothers and one unaffected brother. Importantly, nuclear magnetic resonance solution structure analysis and circular dichroism studies showed this specific mutation to affect the stability of the homeodomain of the NKX3.1 protein and decreased binding to its cognate DNA recognition sequence. These results suggest that germ-line sequence variants in NKX3.1 may play a role in susceptibility to hereditary prostate cancer and underscore a role for NKX3.1 as a prostate cancer gatekeeper.     

Association between genetic polymorphisms of macrophage scavenger receptor 1 gene and risk of prostate cancer in the health professionals follow-up study.

BACKGROUND: Macrophage scavenger receptor 1 (MSR1) is involved in chronic inflammation, which is a risk factor for prostate cancer. Association studies assessing the relationship between sequence variants of MSR1 and prostate cancer are inconsistent. We hypothesized that sequence variants of MSR1 were associated with prostate cancer risk. METHODS: In a nested case-control design within the Health Professionals Follow-up Study, we identified 700 participants with prostate cancer diagnosed after they had provided a blood specimen in 1993 and before January 2000. Controls were 700 age-matched men without prostate cancer who had had a prostate-specific antigen test after providing a blood specimen. We genotyped three common (>5%) single nucleotide polymorphisms (SNP) that have been reported previously to be associated with risk of prostate cancer. RESULTS: None of these MSR1 SNPs nor estimated haplotypes were associated with prostate cancer risk (P for the global test for haplotypes = 0.89). These MSR1 SNPs also did not appear to be associated with higher-grade or advanced-stage prostate cancer. CONCLUSION: The association between these sequence variants of MSR1 and the risk of prostate cancer was null. Further study of aggressive prostate cancer may be warranted, as we had limited power to assess these.     

Role of HPC2/ELAC2 in hereditary prostate cancer

The HPC2/ELAC2 gene on chromosome 17p was recently identified as a candidate gene for hereditary prostate cancer (HPC). To confirm these findings, we screened 300 prostate cancer patients (2 affected members/family) from 150 families with HPC for potential germ-line mutations using conformation-sensitive gel electrophoresis, followed by direct sequence analysis. The minimum criteria for our families with HPC was the presence of 3 affected men with prostate cancer. A total of 23 variants were identified, including 13 intronic and 10 exonic changes. Of the 10 exonic changes, 1 truncating mutation was identified, a Glu216Stop nonsense mutation. This nonsense variant was found in 2 of 3 affected men in a single family. The remaining nine alterations included five missense, three silent, and one variant in the 3' untranslated region. To additionally test for potential associations of polymorphic variants and increased risk for disease, we genotyped two common polymorphisms, Ser217Leu and Ala541Thr, in 446 prostate cancer patients from 164 families with HPC and 502 population-based controls. The frequency of the Leu217 variant was similar for patients (32.3%) and controls (31.8%), as was the frequency of the Thr541 variant (5.4% among patients versus 5.2% among controls). In contrast to previous reports, we found no association of the joint effects of Leu271 and Thr541 (odds ratio, 1.04; 95% confidence interval, 0.57-1.89). Overall, our results did not reveal any association between these two common polymorphisms and the risk for HPC. The finding of a nonsense mutation in the HPC2/ELAC2 gene confirms its potential role in genetic susceptibility to prostate cancer. However, our data also suggest that germ-line mutations of the HPC2/ELAC2 are rare in HPC and that the variants Leu217 and Thr541 do not appear to influence the risk for HPC. Cumulatively, these results suggest that alterations within the HPC2/ELAC2 gene play a limited role in genetic susceptibility to HPC.     

Identification of an aggressive prostate cancer predisposing variant at 11q13

Prostate cancer is the most frequently diagnosed cancer in men; however, the genetic basis of susceptibility remains elusive. The EMSY gene is located in the prostate cancer linked chromosome region at 11q13.5. The aim of this study was to screen EMSY for sequence variants and to evaluate its association with the risk of prostate cancer. We performed a Finnish population-based case-control study with 923 controls, 184 familial prostate cancer cases and 2,301 unselected prostate cancer cases. Variants were screened using sequencing and validated using the TaqMan assay and High Resolution Melting analysis. A total of 27 sequence variants were found, and 17 of them were novel. A rare intronic variant, IVS6-43A>G (minor allele frequency of 0.004), increased the prostate cancer risk in familial cases (odds ratio [OR] = 7.5; 95% confidence interval [CI] = 1.3-45.5; p = 0.02). Further analysis with clinicopathological data revealed that the variant is associated with aggressive unselected cases (prostate specific antigen ≥ 20 μg/L or Gleason grade ≥ 7), based on both case-control (OR = 6.0; 95% CI = 1.3-26.4; p = 0.03) and case-case analyses (OR = 6.5; 95% CI = 1.5-28.4; p = 0.002). In addition, all variant-positive familial cases had aggressive cancer. Our results indicate that the intronic variant IVS6-43A>G increases the familial and unselected prostate cancer risk in a Finnish population and contributes to the aggressive progression of the disease in a high-penetrance manner. The potential role of the variant as a predictive genetic marker for aggressive prostate cancer should be further evaluated.     

Association of RNASEL variants with prostate cancer risk in Hispanic Caucasians and African Americans.

PURPOSE: The RNASEL gene at 1q25 has been identified as a hereditary prostate cancer susceptibility gene, but to date, no study has investigated the role of RNASEL variants in Hispanic Caucasian men with prostate cancer. EXPERIMENTAL DESIGN: Two RNASEL common variants, located at amino acids 462 and 541, were genotyped in non-Hispanic Caucasian, Hispanic Caucasian, and African American prostate cancer cases and controls. RESULTS: The RNASEL 462 AA genotype was found to increase prostate cancer risk over 4-fold in Hispanic Caucasians [odds ratio (OR), 4.43; 95% confidence interval (95% CI), 1.68-11.68; P = 0.003] and over 10-fold in African Americans (OR, 10.41; 95% CI, 2.62-41.40; P = 0.001) when compared with the GG genotype. Analysis of the RNASEL 541 variant showed that Hispanic Caucasian patients with the GG genotype had a statistically significant increase in their risk for developing prostate cancer when compared with the TT and GT genotypes (OR, 1.91; 95% CI, 1.16-3.14; P = 0.01). A common G-T haplotype for the combination of the RNASEL 462 and 541 variants was found to occur more frequently in controls compared with cases in African Americans (P = 0.04) but not in non-Hispanic Caucasians or Hispanic Caucasians. CONCLUSIONS: This is the first study that investigates the association of prostate cancer risk with RNASEL variants in Hispanic men. Our data support the role of RNASEL as a predisposition gene for prostate cancer and showed a significant association between the RNASEL 462 variant and prostate cancer risk in African Americans and Hispanic Caucasians.