Linkage analysis of chromosome 1q markers in 136 prostate cancer families. The Cancer Research Campaign/British Prostate Group U.K. Familial Prostate Cancer Study Collaborators

Compatibility of the radical prostatectomy specimen findings with digital rectal examination

PURPOSE

The purpose of this research is to evaluate the compatibility of the pathological grading of prostate carcinoma in transrectal biopsy sample (TRUS), Gleason scores 3 + 3 = 6, and a palpable nodule in digital rectal examination (DRE) with radical prostatectomy samples in patients with prostate cancer.

METHODS

Sixty-one patients with prostate cancer were included. Transrectal biopsy of the prostate and Gleason score were recorded in the histopathological report of the radical prostatectomy sample independently for each patient.

RESULTS

The mean ± standard deviation of PSA level in patients was 8.52 ± 2.23. The average prostate volume was 46.0 ± 12.17 ml. The average density of PSA was 20.06 ± 7.74 ml. The results revealed that 36% of the people after surgery had similar pathology compared to the score before surgery (Gleason score 3 + 3 = 6) while 64% had non-homogeneous reporting (Gleason score 3 + 4 = 7 and other results). The study showed that low prostate volume before surgery was associated with a higher Gleason score after surgery. Although there was no significant relationship between PSA level above 10 before surgery and higher Gleason scores after surgery, there was a statistically significant relationship between PSA density above 15% and higher Gleason scores after surgery (P < 0.001). PSA density was a strong predictor for postoperative Gleason score (P = 0.004).

CONCLUSION

The high level of PSA density before surgery increased the risk of higher Gleason scores after surgery by 95.99%. Over 64% of the individuals had inconsistency in tumor upgrading, and the palpable firm nodule in the DRE should not be ignored.

Combined CRISPRi and proteomics screening reveal a cohesin-CTCF-bound allele contributing to increased expression of RUVBL1 and prostate cancer progression

Genome-wide association studies along with expression quantitative trait locus (eQTL) mapping have identified hundreds of single-nucleotide polymorphisms (SNPs) and their target genes in prostate cancer (PCa), yet functional characterization of these risk loci remains challenging. To screen for potential regulatory SNPs, we designed a CRISPRi library containing 9,133 guide RNAs (gRNAs) to cover 2,166 candidate SNP loci implicated in PCa and identified 117 SNPs that could regulate 90 genes for PCa cell growth advantage. Among these, rs60464856 was covered by multiple gRNAs significantly depleted in screening (FDR < 0.05). Pooled SNP association analysis in the PRACTICAL and FinnGen cohorts showed significantly higher PCa risk for the rs60464856 G allele (p value = 1.2 × 10-16 and 3.2 × 10-7, respectively). Subsequent eQTL analysis revealed that the G allele is associated with increased RUVBL1 expression in multiple datasets. Further CRISPRi and xCas9 base editing confirmed that the rs60464856 G allele leads to elevated RUVBL1 expression. Furthermore, SILAC-based proteomic analysis demonstrated allelic binding of cohesin subunits at the rs60464856 region, where the HiC dataset showed consistent chromatin interactions in prostate cell lines. RUVBL1 depletion inhibited PCa cell proliferation and tumor growth in a xenograft mouse model. Gene-set enrichment analysis suggested an association of RUVBL1 expression with cell-cycle-related pathways. Increased expression of RUVBL1 and activation of cell-cycle pathways were correlated with poor PCa survival in TCGA datasets. Our CRISPRi screening prioritized about one hundred regulatory SNPs essential for prostate cell proliferation. In combination with proteomics and functional studies, we characterized the mechanistic role of rs60464856 and RUVBL1 in PCa progression.

Combined CRISPRi and proteomics screening reveal a cohesin-CTCF-bound allele contributing to increased expression of RUVBL1 and prostate cancer progression

Genome-wide association studies along with expression quantitative trait loci (eQTL) mapping have identified hundreds of single nucleotide polymorphisms (SNPs) and their target genes in prostate cancer (PCa), yet functional characterization of these risk loci remains challenging. To screen for potential regulatory SNPs, we designed a CRISPRi library containing 9133 guide RNAs (gRNAs) to target 2,166 candidate SNP sites implicated in PCa and identified 117 SNPs that could regulate 90 genes for PCa cell growth advantage. Among these, rs60464856 was covered by multiple gRNAs significantly depleted in the screening (FDR<0.05). Pooled SNP association analysis in the PRACTICAL and FinnGen cohorts showed significantly higher PCa risk for the rs60464856 G allele (pvalue=1.2E-16 and 3.2E-7). Subsequent eQTL analysis revealed that the G allele is associated with increased RUVBL1 expression in multiple datasets. Further CRISPRi and xCas9 base editing proved the rs60464856 G allele leading to an elevated RUVBL1 expression. Furthermore, SILAC-based proteomic analysis demonstrated allelic binding of cohesin subunits at the rs60464856 region, where HiC dataset showed consistent chromatin interactions in prostate cell lines. RUVBL1 depletion inhibited PCa cell proliferation and tumor growth in xenograft mouse model. Gene set enrichment analysis suggested an association of RUVBL1 expression with cell-cycle-related pathways. An increased expression of RUVBL1 and activations of cell-cycle pathways were correlated with poor PCa survival in TCGA datasets. Together, our CRISPRi screening prioritized about one hundred regulatory SNPs essential for prostate cell proliferation. In combination with proteomics and functional studies, we characterized the mechanistic role of rs60464856 and RUVBL1 in PCa progression.

Identification of Germline Genetic Variants that Increase Prostate Cancer Risk and Influence Development of Aggressive Disease

Prostate cancer (PrCa) is a heterogeneous disease, which presents in individual patients across a diverse phenotypic spectrum ranging from indolent to fatal forms. No robust biomarkers are currently available to enable routine screening for PrCa or to distinguish clinically significant forms, therefore late stage identification of advanced disease and overdiagnosis plus overtreatment of insignificant disease both remain areas of concern in healthcare provision. PrCa has a substantial heritable component, and technological advances since the completion of the Human Genome Project have facilitated improved identification of inherited genetic factors influencing susceptibility to development of the disease within families and populations. These genetic markers hold promise to enable improved understanding of the biological mechanisms underpinning PrCa development, facilitate genetically informed PrCa screening programmes and guide appropriate treatment provision. However, insight remains largely lacking regarding many aspects of their manifestation; especially in relation to genes associated with aggressive phenotypes, risk factors in non-European populations and appropriate approaches to enable accurate stratification of higher and lower risk individuals. This review discusses the methodology used in the elucidation of genetic loci, genes and individual causal variants responsible for modulating PrCa susceptibility; the current state of understanding of the allelic spectrum contributing to PrCa risk; and prospective future translational applications of these discoveries in the developing eras of genomics and personalised medicine.

Admixture Mapping Links RACGAP1 Regulation to Prostate Cancer in African Americans

BACKGROUND/AIM

Prostate cancer is the most common malignancy in US males. African American men have higher incidence and mortality rates than European Americans. Five single nucleotide polymorphisms are associated with PCa. We hypothesized haplotypes inferred from these SNPs are also associated with PCa.

PATIENTS AND METHODS

We genotyped SNPs in a case-control admixture mapping study. SNP haplotypes inferred for 157 PCa cases and 150 controls were used in the regression analysis.

RESULTS

We found an association between "GTCCC", "ATTCT", and "ACCCC" haplotypes and PCa after ancestry adjustment (OR=3.62, 95%CI=1.42-9.21, p=0.0070; OR=7.89, 95%CI=2.36-26.31, p=0.0008; OR=4.34, 95%CI=1.75-10.78, p=0.0016). The rs615382 variant disrupts the recombination signal binding protein with immunoglobulin kappa J binding site in Rac GTPase activating protein 1 (RACGAP1).

CONCLUSION

Disruption of notch 1 mediated-repression of RACGAP1 may contribute to PCa in African Americans.

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.

NF-κB gene signature predicts prostate cancer progression

In many patients with prostate cancer, the cancer will be recurrent and eventually progress to lethal metastatic disease after primary treatment, such as surgery or radiation therapy. Therefore, it would be beneficial to better predict which patients with early-stage prostate cancer would progress or recur after primary definitive treatment. In addition, many studies indicate that activation of NF-κB signaling correlates with prostate cancer progression; however, the precise underlying mechanism is not fully understood. Our studies show that activation of NF-κB signaling via deletion of one allele of its inhibitor, IκBα, did not induce prostatic tumorigenesis in our mouse model. However, activation of NF-κB signaling did increase the rate of tumor progression in the Hi-Myc mouse prostate cancer model when compared with Hi-Myc alone. Using the nonmalignant NF-κB-activated androgen-depleted mouse prostate, a NF-κB-activated recurrence predictor 21 (NARP21) gene signature was generated. The NARP21 signature successfully predicted disease-specific survival and distant metastases-free survival in patients with prostate cancer. This transgenic mouse model-derived gene signature provides a useful and unique molecular profile for human prostate cancer prognosis, which could be used on a prostatic biopsy to predict indolent versus aggressive behavior of the cancer after surgery.

The genetic epidemiology of prostate cancer and its clinical implications

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

Prostate cancer: germline prediction for a commonly variable malignancy

What's known on the subject? and What does the study add? Prostate cancer is a heterogeneous disease and biomarkers to predict its incidence and subsequent clinical behaviour are needed to tailor screening, prevention and therapeutic strategies. Rare mutations in genes such as BRCA1, BRCA2 and HOXB13 can affect prostate cancer incidence and/or clinical behaviour. Genome wide association studies (GWAS) have identified more common genetic variations that explain an estimated 20% of familial prostate cancer risk. In this review, we focus on the potential of germline genetic variation to provide biomarkers for prostate cancer screening, prevention and management. We discuss how germline genetics may have a role in treatment selection if reliable pharmacogenetic predictors of efficacy and toxicity can be identified. We have outlined possible mechanisms for including germline investigation in future prostate cancer clinical trials.

OBJECTIVES

• Prostate cancer is a heterogeneous disease and biomarkers to predict its incidence and subsequent clinical behaviour are needed to tailor screening, prevention and therapeutic strategies. • In this review we focus on the potential of germline genetic variation to provide these biomarkers.

METHODS

• We review the published literature on germline genetics in prostate cancer and examine the possibility of including germline genetic biomarkers in future prostate cancer clinical trials.

RESULTS

• Rare mutations in genes such as BRCA1, BRCA2 and HOXB13 can affect prostate cancer incidence and/or clinical behaviour. • Genome-wide association studies (GWAS) have identified more common genetic variations that explain an estimated 20% of familial prostate cancer risk. • Germline genetics may have a role in treatment selection, if reliable pharmacogenetic predictors of efficacy and toxicity can be identified.

CONCLUSION

• This rapidly emerging area of prostate cancer research may provide answers to current clinical conundrums in the prostate cancer treatment paradigm. We have outlined possible mechanisms for including germline investigation in future prostate cancer clinical trial design.

The genetics of cancer risk

One hundred years ago, decades before the discovery of the structure of DNA, debate raged regarding how human traits were passed from one generation to the next. Phenotypes, including risk of disease, had long been recognized as having a familial component. Yet it was difficult to reconcile genetic segregation as described by Mendel with observations exhaustively documented by Karl Pearson and others regarding the normal distribution of human characteristics. In 1918, R. A. Fisher published his landmark article, "The Correlation Between Relatives on the Supposition of Mendelian Inheritance," bridging this divide and demonstrating that multiple alleles, all individually obeying Mendel's laws, account for the phenotypic variation observed in nature.Since that time, geneticists have sought to identify the link between genotype and phenotype. Trait-associated alleles vary in their frequency and degree of penetrance. Some minor alleles may approach a frequency of 50% in the human population, whereas others are present within only a few individuals. The spectrum for penetrance is similarly wide. These characteristics jointly determine the segregation pattern of a given trait, which, in turn, determine the method used to map the trait. Until recently, identification of rare, highly penetrant alleles was most practical. Revolutionary studies in genomics reported over the past decade have made interrogation of most of the spectrum of genetic variation feasible.The following article reviews recent discoveries in the genetic basis of inherited cancer risk and how these discoveries inform cancer biology and patient management. Although this article focuses on prostate cancer, the principles are generic for any cancer and, indeed, for any trait.

New variants at 10q26 and 15q21 are associated with aggressive prostate cancer in a genome-wide association study from a prostate biopsy screening cohort

PURPOSE

To identify and examine polymorphisms of genes associated with aggressive and clinical significant forms of prostate cancer among a screening cohort.

EXPERIMENTAL DESIGN

We conducted a genome-wide association study among patients with aggressive forms of prostate cancer and biopsy-proven normal controls ascertained from a prostate cancer screening program. We then examined significant associations of specific polymorphisms among a prostate cancer screened cohort to examine their predictive ability in detecting prostate cancer.

RESULTS

We found significant associations between aggressive prostate cancer and five single nucleotide polymorphisms (SNPs) in the 10q26 (rs10788165, rs10749408, and rs10788165, p value for association 1.3 × 10(-10 ) to 3.2 × 10(-11) ) and 15q21 (rs4775302 and rs1994198, p values for association 3.1 × 10(-8 ) to 8.2 × 10(-9)) regions. Results of a replication study done in 3439 patients undergoing a prostate biopsy, revealed certain combinations of these SNPs to be significantly associated not only with prostate cancer but with aggressive forms of prostate cancer using an established classification criterion for prostate cancer progression (odds ratios for intermediate to high-risk disease 1.8-3.0, p value 0.003-0.001). These SNP combinations were also important clinical predictors for prostate cancer detection based on nomogram analysis that assesses prostate cancer risk.

CONCLUSIONS

Five SNPs were found to be associated with aggressive forms of prostate cancer. We demonstrated potential clinical applications of these associations.

Genetics of prostate cancer risk

For decades, physicians and researchers have recognized that family history is a significant risk factor for prostate cancer. The identification of the genes responsible for inherited risk, however, proved difficult. With the sequencing of the human genome and the completion of the initial phases of the International HapMap Project, the tools are available to scan the entire genome and find genetic markers for disease. Since 2006, more than 30 inherited variants strongly associated with prostate cancer have been reported. As the inherited component of the disease is revealed, efforts are ongoing to translate genetic findings into the clinic.

The prevention of prostate cancer

From our better understanding of the natural history of prostate cancer, it is not unreasonable to believe that the disease is preventable. Prostate cancer has become a major healthcare problem worldwide, as life expectancy increases. Moreover, the cancer is slow growing, with a period of about 20-25 years from initiation to the stage when the clinically detectable phenotype can be identified. This review provides a simple overview of the endocrinology of prostate cancer and discusses some of the pharmaceutical agents that have been or are being tested to restrain, possibly arrest, the progression of this slowly growing cancer. Also discussed are many of the dietary factors that may influence the molecular or endocrine events implicated in its development. Dietary factors are considered responsible for the geographical differences in prostate cancer incidence and mortality. Since about 50% of all men worldwide, from both East and West, show evidence of microscopic cancer by 50 years of age, growth restraint would appear to be the pragmatic option to the possibility of preventing initiation.

Molecular biology of prostate-cancer pathogenesis

PURPOSE OF REVIEW

The genetic and molecular basis of prostate-cancer pathogenesis is reviewed.

RECENT FINDINGS

Several genetic loci have been found that are associated with hereditary predisposition to prostate cancer, but they account for a small fraction of all cases. A number of suppressor genes have been identified that are activated by either complete or partial genetic loss in sporadic prostate cancer. Chromosomal translocation results in transcriptional activation of truncated ETS transcription factors ERG and ETV1, the first candidates for dominant oncogenes for prostate cancer. Lastly, the androgen receptor is active throughout the course of prostate cancer and, in androgen-independent prostate cancer, takes on the role of a dominant oncogene as the target of gene amplification, overexpression, and the activation of mutations.

SUMMARY

Genetic lesions responsible for familial and sporadic prostate cancer are being revealed and they suggest that prostate cancer often initiates owing to an increased susceptibility to oxidative damage; it then progresses by affecting transcription factors, the PI3 kinase pathway, and other growth stimulatory pathways. The final common pathway after androgen ablation appears to be activation of androgen receptor.

Molecular changes in prostatic cancer

Prostate cancer is one of the most commonly diagnosed and potentially devastating cancers in men, throughout the world. However, the clinical manifestation of this disease varies greatly, from indolent tumours, requiring little or no treatment, to those aggressive cancers which require radical therapies. Prostate cancer, like all other cancers, develops and progresses as a consequence of an accumulation of genetic changes. While several putative genes have been isolated for the development of breast, ovarian and colon cancer, the aetiology and pathogenesis of prostate cancer remains poorly understood. In this review, we discuss important genetic markers in early, metastatic and hormone refractory prostate cancer which may, in the future, be used as markers for diagnosis and prognosis, as well as targets for therapeutic intervention.

Finding prostate cancer susceptibility genes

Prostate cancer is a heterogeneous disease with multiple loci contributing to susceptibility. Traditionally, genome-wide scans using high-risk families have utilized stratification by number of affected individuals, family history of other cancers, or family age at diagnosis to improve genetic homogeneity. In addition to locus heterogeneity, for later onset diseases such as prostate cancer, a major limitation to mapping efforts is that key parental DNA samples are rarely available. The lack of available samples from upper generations reduces inheritance information, and as a result, the standard 10-cM genome scan does not provide full power to detect linkage. To increase the ability to find disease-associated loci, much denser genome-wide scans must be undertaken in multiple ethnic groups. In addition, new ways of defining homogenous subsets of families need to be developed.

Unravelling the genetics of prostate cancer

This review describes what is currently known about the genetics of prostate cancer. Traditionally, the genetics of a suspected inherited cancer predisposition have generally been thought of in terms of a single, high-risk gene with a dominant mode of inheritance. Such a gene might be observed in families, as has been documented in familial breast cancer (BRCA1/2), familial colorectal cancer (HNPCC), retinoblastoma (RB1), and Wilms tumor (WT1). This review investigates the evidence for the existence, first of familial prostate cancer, and second, for the presence of such a high-risk gene in those families by epidemiological and experimental approaches. Another current area of interest in prostate cancer is the investigation of the contribution of common lower penetrance genes to the disease. This alternative approach has become popular, as it raises the issue of frequently seen genetic variations such as single nucleotide polymorphisms (SNPs) having relevance to the risk of developing the disease. Finally, this article will explore the way forward, with emphasis on worldwide collaboration from teams attempting to find the genes responsible for the disease and investment in new technologies that will aid in their discovery.

The clinical genetics of prostate cancer

Prostate cancer is the most common cancer in men and the second highest cause of cancer-related mortality in the U.K. A genetic component in predisposition to prostate cancer has been recognized for decades. One of the strongest epidemiological risk factors for prostate cancer is a positive family history. The hunt for the genes that predispose to prostate cancer in families has been the focus of many research groups worldwide for the past 10 years. Both epidemiological and twin studies support a role for genetic predisposition to prostate cancer. Familial cancer loci have been found, but the genes that cause familial prostate cancer remain largely elusive. Unravelling the genetics of prostate cancer is challenging and is likely to involve the analysis of numerous predisposition genes. Current evidence supports the hypothesis that excess familial risk of prostate cancer could be due to the inheritance of multiple moderate-risk genetic variants. Although research on hereditary prostate cancer has improved our knowledge of the genetic aetiology of the disease, a lot of questions still remain unanswered.

This article explores the current evidence that there is a genetic component to the aetiology of prostate cancer and attempts to put into context the diverse findings that have been shown to be possibly associated with the development of hereditary prostate cancer. Linkage searches over the last decade are summarised. It explores issues as to why understanding the genetics of prostate cancer has been so difficult and why despite this, it is still a major focus of research. Finally, current and future management strategies of men with Hereditary Prostate Cancer (HPC) are discussed.

Identification of a prostate cancer susceptibility locus on chromosome 7q11-21 in Jewish families

Results from over a dozen prostate cancer susceptibility genome-wide scans, encompassing some 1,500 hereditary prostate cancer families, indicate that prostate cancer is an extremely heterogeneous disease with multiple loci contributing to overall susceptibility. In an attempt to reduce locus heterogeneity, we performed a genomewide linkage scan for prostate cancer susceptibility genes with 36 Jewish families, which represent a stratification of hereditary prostate cancer families with potentially increased locus homogeneity. The 36 Jewish families represent a combined dataset of 17 Jewish families from the Fred Hutchinson Cancer Research Center-based Prostate Cancer Genetic Research Study dataset and 19 Ashkenazi Jewish families collected at Johns Hopkins University. All available family members, including 94 affected men, were genotyped at markers distributed across the genome with an average interval of <10 centimorgans. Nonparametric multipoint linkage analyses were the primary approach, although parametric analyses were performed as well. Our strongest signal was a significant linkage peak at 7q11-21, with a nonparametric linkage (NPL) score of 3.01 (P = 0.0013). Simulations indicated that this corresponds to a genomewide empirical P = 0.006. All other regions had NPL P values >/=0.02. After genotyping additional markers within the 7q11-21 peak, the NPL score increased to 3.35 (P = 0.0004) at D7S634 with an allele-sharing logarithm of odds of 3.12 (P = 0.00007). These studies highlight the utility of analyzing defined sets of families with a common origin for reducing locus heterogeneity problems associated with studying complex traits.

Clinical models for testing chemopreventative agents in prostate cancer and overview of SELECT: the Selenium and Vitamin E Cancer Prevention Trial

Target populations for chemoprevention trials should include those at higher than average risk for the development of prostate cancer as defined by explicit epidemiologic and genetic criteria. Such populations include a "primary prevention" group without histologic or clinical evidence of cancer, and several clinical models of "secondary prevention," including those with clinically evident disease prior to definitive therapy and those at high risk of recurrence after therapy based on histology and/or biochemical status. Each risk group and clinical model has potential advantages and disadvantages, and the mechanisms which underlie disease development and progression in each group may be unique. These observations give rise to many potential clinical trials of specific agents. These trials should also include collection of data on potentially confounding influences on disease development and progression. Preclinical, epidemiologic, and Phase II data suggest that both selenium and vitamin E have potential efficacy in prostate cancer prevention. The experience of the Prostate Cancer Prevention Trial (PCPT) demonstrates the interest and dedication of healthy men to long-term studies of cancer prevention. SELECT, the Selenium and Vitamin E Cancer Prevention Trial, is an intergroup phase III, randomized, double-blind, placebo-controlled, population-based clinical trial designed to test the efficacy of selenium and vitamin E alone and in combination in the prevention of prostate cancer which builds on secondary analyses of large-scale chemoprevention trials for other cancers and the lessons of PCPT.

Genetic susceptibility to prostate cancer: a review

A genetic component in prostate cancer has been recognized since decades. Through numerous epidemiological and molecular biological studies, much evidence has accumulated in favor of a significant but heterogeneous hereditary component in prostate cancer (PCa) susceptibility. Since the mapping of a high-penetrant PCa susceptibility locus at 1q24-25, much attention has been paid to the identification of PCa susceptibility genes. So far, seven loci have been mapped, and at three of these loci, genes have been cloned and mutations identified. Yet their role in hereditary and sporadic disease is still under debate and probably very modest. Although research on hereditary prostate cancer has improved our knowledge of the genetic etiology of the disease, still a lot of questions remain unanswered. Here, we aim to review the genetic epidemiological and molecular biological research in the field of hereditary prostate cancer and the problems that are encountered with this research.

Where are the prostate cancer genes?--A summary of eight genome wide searches

BACKGROUND

There is strong evidence for genetic susceptibility to prostate cancer, but most of the genes underlying this susceptibility remain to be identified.

METHODS

We reviewed the results of eight genome-wide linkage searches based on 1,293 families with multiple cases of prostate cancer.

RESULTS

Across these studies, 11 linkage peaks with LOD scores in excess of 2 were identified. However, no chromosomal region was reported as significant at this level by more than one study and only one corresponded to a peak previously suggested by another group.

CONCLUSIONS

These results indicate that prostate cancer is genetically complex, and that combined analyses of large family sets will be required to evaluate reliably the linkage evidence.

Genome-wide scan of Swedish families with hereditary prostate cancer: suggestive evidence of linkage at 5q11.2 and 19p13.3

BACKGROUND

Prostate cancer (CaP) is a common disorder with multiple genetic and environmental factors contributing to the disease. CaP susceptibility loci can be identified through genome-wide scans of high-risk families.

METHODS

Allele sharing at 405 markers, distributed across the genome, among 50 families with hereditary prostate cancer, ascertained throughout Sweden, was evaluated through linkage analyses. Genotype data were analyzed utilizing multipoint parametric and non-parametric methods.

RESULTS

Two regions provided suggestive evidence for linkage: 19p13.3 (marker D19S209, LOD = 2.91, P = 0.0001) and 5q11.2 (marker D5S407, LOD = 2.24, P = 0.0007). Additional regions with moderate evidence for linkage in the complete set of families, or stratified subsets, were observed on chromosome 1, 4, 6, 7, 8, and X.

CONCLUSIONS

Our results provide strong confirmatory evidence of linkage at 19q13.3 and 5q11.2. The lack of confirmation of linkage at several loci identified in other genome-wide scans emphasizes the need to combine linkage data between research groups.

Genomic scan of 254 hereditary prostate cancer families

Hereditary prostate cancer (HPC) is a genetically heterogeneous disease, complicating efforts to map and clone susceptibility loci. We have used stratification of a large dataset of 254 HPC families in an effort to improve power to detect HPC loci and to understand what types of family features may improve locus identification. The strongest result is that of a dominant locus at 6p22.3 (heterogeneity LOD (HLOD) = 2.51), the evidence for which is increased by consideration of the age of PC onset (HLOD = 3.43 in 214 families with median age-of-onset 56-72 years) and co-occurrence of primary brain cancer (HLOD = 2.34 in 21 families) in the families. Additional regions for which we observe modest evidence for linkage include chromosome 7q and 17p. Only weak evidence of several previously implicated HPC regions is detected. These analyses support the existence of multiple HPC loci, whose presence may be best identified by analyses of large, including pooled, datasets which consider locus heterogeneity.

Results of a genome-wide linkage analysis in prostate cancer families ascertained through the ACTANE consortium

BACKGROUND

The aggregation of prostate cancer within families suggests a major inherited component to the disease. Genetic linkage studies have identified several chromosomal regions that may contain prostate cancer susceptibility loci, but none has been definitively implicated.

METHODS

We performed a genome-wide linkage search based on 64 families, 63 with at least 3 cases of prostate cancer, ascertained in five countries. The majority of cases from these centers presented with clinically detected disease. Four hundred and one polymorphic markers were typed in 268 individuals. Multipoint heterogeneity analysis was conducted under three models of susceptibility; non-parametric analyses were also performed.

RESULTS

Some weak evidence of linkage, under at least one of the genetic models, was observed to markers on chromosomes 2 (heterogeneity LOD (HLOD) = 1.15, P = 0.021), 3 (HLOD = 1.25, P = 0.016), 4 (HLOD = 1.28, P = 0.015), 5 (HLOD = 1.20, P = 0.019), 6 (HLOD = 1.41, P = 0.011), and 11 (HLOD = 1.24, P = 0.018), and in two regions on chromosome 18 (HLOD = 1.40, P = 0.011 and HLOD = 1.34, P = 0.013). There were no HLOD scores greater than 1.5 under any model, and no locus would be predicted to explain more than half of the genetic effect. No evidence in favor of linkage to previously suggested regions on chromosomes 1, 8, 17, 20, or X was found.

CONCLUSIONS

Genetic susceptibility to prostate cancer is likely to be controlled by many loci, with no single gene explaining a large fraction of the familial risk. Pooling of results from all available genome scans is likely to be required to obtain definitive linkage results.

Genome linkage screen for prostate cancer susceptibility loci: results from the Mayo Clinic Familial Prostate Cancer Study

Prostate cancer is one of the most common cancers among men and has long been recognized to occur in familial clusters. Brothers and sons of affected men have a twofold to threefold increased risk of developing prostate cancer. However, identification of genetic susceptibility loci for prostate cancer has been extremely difficult. Several putative loci identified by genetic linkage have been reported to exist on chromosomes 1 (HPC1, PCAP, and CAPB), X (HPCX), 17 (HPC2), and 20 (HPC20), with genes RNASEL (HPC1) and ELAC2 (HPC2) tentatively defined. In this study, we report our genome linkage scan in 160 prostate cancer families, using the ABI Prism Linkage Mapping Set Version 2 with 402 microsatellite markers. The most significant linkage was found for chromosome 20, with a recessive model heterogeneity LOD score (HLOD) of 4.77, and a model-free LOD score (LOD - ZLR) of 3.46 for the entire group of pedigrees. Linkage for chromosome 20 was most prominent among families with a late age of diagnosis (average age at diagnosis >/= 66 years; maximum LOD - ZLR = 2.82), with <5 affected family members (LOD - ZLR = 3.02), with presence of hereditary prostate cancer (LOD - ZLR = 2.81), or with no male-to-male transmission of disease (LOD - ZLR = 3.84). No other chromosome showed significant evidence for linkage. However, chromosomes 6 and X showed suggestive results, with maximum LOD - ZLR values of 1.38 and 1.36, respectively. Subset analyses suggest additional chromosomal regions worth further follow-up.

Oligogenic segregation analysis of hereditary prostate cancer pedigrees: evidence for multiple loci affecting age at onset

Previous studies have suggested strong evidence for a hereditary component to prostate cancer (PC) susceptibility. Here, we analyze 3,796 individuals in 263 PC families recruited as part of the ongoing Prostate Cancer Genetic Research Study (PROGRESS). We use Markov chain Monte Carlo (MCMC) oligogenic segregation analysis to estimate the number of quantitative trait loci (QTLs) and their contribution to the variance in age at onset of hereditary PC (HPC). We estimate 2 covariate effects: diagnosis of PC before and after prostate-specific antigen (PSA) test availability, and presence/absence of at least 1 blood relative with primary neuroepithelial brain cancer (BC). We find evidence that 2 to 3 QTLs contribute to the variance in age at onset of HPC. The 2 QTLs with the largest contribution to the total variance are both effectively dominant loci. We find that the covariate for diagnosis before and after PSA test availability is important. Our findings for the number of QTLs contributing to HPC and the variance contribution of these QTLs will be instructive in mapping and identifying these genes.

Prostate cancer epidemiology

Because more and more men are being diagnosed with prostate cancer worldwide, knowledge about and prevention of this disease is important. Epidemiological studies have provided some insight about the cause of prostate cancer in terms of diet and genetic factors. However, compared with other common cancers such as breast and lung cancer, the causes remain poorly understood. Several important issues could help in our understanding of this disease-the variation in incidence of prostate cancer between ethnic populations and the factors leading to familial clustering of the diseases.

RNASEL Arg462Gln variant is implicated in up to 13% of prostate cancer cases

RNASEL (encoding ribonuclease L) has recently been proposed as a candidate for the hereditary prostate cancer (HPC1) gene. We determined that the RNASEL variant Arg462Gln has three times less enzymatic activity than the wildtype and is significantly associated with prostate cancer risk (P = 0.007). At least one copy of the mutated allele that causes this substitution is carried by nearly 60% of the men in our study. Men that are heterozygous with respect to the mutated allele have 50% greater risk of prostate cancer than non-carriers, and homozygotes have more than double the risk.

Hereditary prostate cancer: clinical aspects

PURPOSE

We review the current epidemiological and genetic knowledge regarding hereditary prostate cancer, and outline its clinical implications.

MATERIALS AND METHODS

Published articles on hereditary prostate cancer were identified using the MEDLINE data base.

RESULTS

A risk of prostate cancer, particularly early onset disease, is strongly affected by family history (number of relatives with prostate cancer and their age at diagnosis). A family history of prostate cancer increases the positive predictive value of prostate specific antigen testing and, hence, heredity should always be assessed when deciding whether to perform biopsies in a man with a prostate specific antigen level of 3 to 10 ng./ml. Epidemiological studies indicate that dominantly inherited susceptibility genes with high penetrance cause 5% to 10% of all prostate cancer cases, and as much as 30% to 40% of early onset disease. More than a half dozen chromosome loci that may comprise such genes have been mapped, but as of May 2002 no prostate cancer susceptibility gene of major importance had been cloned. Most likely, environmental factors and comparatively common variants of several other genes affect prostate cancer risk in families with or without multiple cases of the disease. On average, hereditary prostate cancer is diagnosed 6 to 7 years earlier than sporadic prostate cancer, but does not otherwise differ clinically from the sporadic form. As a consequence of the earlier onset, a greater proportion of men with hereditary prostate cancer die of the disease than those with nonhereditary prostate cancer. At present, the only clinically applicable measure to reduce prostate cancer mortality in families with hereditary disease is screening, with the aim of diagnosing the disease when it is still in a curable stage.

CONCLUSIONS

Hereditary susceptibility is now considered the strongest risk factor for prostate cancer and has profound clinical importance. The genetic mechanism behind such susceptibility has turned out to be more complex than initially thought, and will probably not be completely understood for many years to come.

Perspective: prostate cancer susceptibility genes

In many developed countries, prostate cancer is the most frequently diagnosed malignancy in men. The extent to which the marked racial/ethnic difference in its incidence rate is attributable to screening methods, environmental, hormonal, and/or genetic factors remains unknown. A positive family history is among the strongest epidemiological risk factors for prostate cancer. It is now well recognized that association of candidate genetic markers to this multifactorial malignancy is more difficult than the identification of susceptibility genes for some common cancers such as breast, ovary, and colon cancer. Several reasons may explain such a difficulty: 1) prostate cancer is diagnosed at a late age, thus often making it impossible to obtain DNA samples from living affected men for more than one generation; 2) the presence within high-risk pedigrees of phenocopies, associated with the lack of distinguishing features between hereditary and sporadic forms; and 3) the genetic heterogeneity of this complex disease along with the accompanying difficulty of developing appropriate statistical transmission models taking into account simultaneously multiple susceptibility genes, frequently showing moderate or low penetrance. Despite the localization of seven susceptibility loci, there has been limited confirmatory evidence of linkage for currently known candidate genes. Nonetheless, the discovery of the first prostate cancer susceptibility gene characterized by positional cloning, ELAC2 was achieved taking advantage of the Utah Family Resource. Moreover, common missense mutations in the ELAC2 gene were found to be significantly associated with an increased risk of diagnosis of prostate cancer in some studies. More recently, recombination map-ping and candidate gene analysis were used to map several genes, including the 2'-5'-oligoadenylate-dependent ribonuclease L (RNASEL) gene, to the critical region of HPC1. Two deleterious mutations in RNASEL segregate independently with the disease in two of the eight HPC1-linked families. Additional studies using larger cohorts are needed to fully evaluate the role of these two susceptibility genes in prostate cancer risk. Although a number of rare highly penetrant loci contribute to the Mendelian inheritance of prostate cancer, some of the familial risks may be due to shared environment and more specifically to common low-penetrance genetic variants. In this regard, it is not surprising that analyses of genes encoding key proteins involved in androgen biosynthesis and action, led to the observation of a significant association between a susceptibility to prostate cancer and common genetic variants, such as those found in 5alpha-reductase type 2 and AR genes.

A genome screen of families with multiple cases of prostate cancer: evidence of genetic heterogeneity

We conducted a genomewide screen for prostate cancer-susceptibility genes on the basis of data from 98 families from the United States and Canada that had three or more verified diagnoses of prostate cancer among first- and second-degree relatives. We found a statistically significant excess of markers for which affected relatives exhibited modest amounts of excess allele-sharing; however, no single chromosomal region contained markers with excess allele-sharing of sufficient magnitude to indicate unequivocal evidence of linkage. Positive linkage signals of nominal statistical significance were found in two regions (5p-q and 12p) that have been identified as weakly positive in other data sets and in region 19p, which has not been identified previously. All these signals were considerably stronger for analyses restricted to families with mean age at onset below the median than for analyses of families with mean age at onset above the median. The data provided little support for any of the putative prostate cancer-susceptibility genes identified in other linkage studies.

Model-free linkage analysis with covariates confirms linkage of prostate cancer to chromosomes 1 and 4

As with many complex genetic diseases, genome scans for prostate cancer have given conflicting results, often failing to provide replication of previous findings. One factor contributing to the lack of consistency across studies is locus heterogeneity, which can weaken or even eliminate evidence for linkage that is present only in a subset of families. Currently, most analyses either fail to account for locus heterogeneity or attempt to account for it only by partitioning data sets into smaller and smaller portions. In the present study, we model locus heterogeneity among affected sib pairs with prostate cancer by including covariates in the linkage analysis that serve as surrogate measures of between-family linkage differences. The model is a modification of the Olson conditional logistic model for affected relative pairs. By including Gleason score, age at onset, male-to-male transmission, and/or number of affected first-degree family members as covariates, we detected linkage near three locations that were previously identified by linkage (1q24-25 [HPC1; LOD score 3.25, P=.00012], 1q42.2-43 [PCAP; LOD score 2.84, P=.0030], and 4q [LOD score 2.80, P=.00038]), near the androgen-receptor locus on Xq12-13 (AR; LOD score 3.06, P=.00053), and at five new locations (LOD score > 2.5). Without covariates, only a few weak-to-moderate linkage signals were found, none of which replicate findings of previous genome scans. We conclude that covariate-based linkage analysis greatly improves the likelihood that linked regions will be found by incorporation of information about heterogeneity within the sample.

Potential target populations and clinical models for testing chemopreventive agents

Target populations for chemoprevention trials should include those at higher than average risk for the development of prostate cancer as defined by explicit epidemiologic and genetic criteria. Such populations include a "primary prevention" group without histologic or clinical evidence of cancer, and several clinical models of "secondary prevention," including those with clinically evident disease prior to definitive therapy and those at high risk of recurrence after therapy based on histological or biochemical status. Each risk group and clinical model has potential advantages and disadvantages, and the mechanisms that underlie disease development and progression in each group may be unique. These observations give rise to many potential clinical trials of specific agents. These trials should also include collection of data on potentially confounding influences on disease development and progression.

Evaluation of linkage and association of HPC2/ELAC2 in patients with familial or sporadic prostate cancer

To investigate the relationship between HPC2/ELAC2 and prostate cancer risk, we performed the following analyses: (1) a linkage study of six markers in and around the HPC2/ELAC2 gene at 17p11 in 159 pedigrees with hereditary prostate cancer (HPC); (2) a mutation-screening analysis of all coding exons of the gene in 93 probands with HPC; (3) family-based and population-based association study of common HPC2/ELAC2 missense variants in 159 probands with HPC, 249 patients with sporadic prostate cancer, and 222 unaffected male control subjects. No evidence for linkage was found in the total sample, nor in any subset of pedigrees based on characteristics that included age at onset, number of affected members, male-to-male disease transmission, or race. Furthermore, only the two previously reported missense changes (Ser217Leu and Ala541Thr) were identified by mutational analysis of all HPC2/ELAC exons in 93 probands with HPC. In association analyses, family-based tests did not reveal excess transmission of the Leu217 and/or Thr541 alleles to affected offspring, and population-based tests failed to reveal any statistically significant difference in the allele frequencies of the two polymorphisms between patients with prostate cancer and control subjects. The results of this study lead us to reject the three alternative hypotheses of (1) a highly penetrant, major prostate cancer-susceptibility gene at 17p11, (2) the allelic variants Leu217 or Thr541 of HPC2/ELAC2 as high-penetrance mutations, and (3) the variants Leu217 or Thr541 as low-penetrance, risk-modifying alleles. However, we did observe a trend of higher Leu217 homozygous carrier rates in patients than in control subjects. Considering the impact of genetic heterogeneity, phenocopies, and incomplete penetrance on the linkage and association studies of prostate cancer and on the power to detect linkage and association in our study sample, our results cannot rule out the possibility of a highly penetrant prostate cancer gene at this locus that only segregates in a small number of pedigrees. Nor can we rule out a prostate cancer-modifier gene that confers a lower-than-reported risk. Additional larger studies are needed to more fully evaluate the role of this gene in prostate cancer risk.

Cellular and molecular pathology of prostate cancer precursors

Prostate cancer is usually heterogeneous and multifocal, with diverse clinical and morphologic manifestations. Current understanding of the molecular basis for this heterogeneity is limited, particularly for prostatic intraepithelial neoplasia (PIN), the only putative precursor which can be identified according to morphologic criteria. However, it is likely that prostatic adenocarcinoma might arise from precursor lesions other than PIN, although these cannot be recognized with certainty at the present time. In this review, we summarize the current state of knowledge regarding the cell-biological and genetic bases for linking PIN and prostatic adenocarcinoma. It is conceivable that a stem cell of basal phenotype, or an amplifying cell, is the target of prostatic carcinogenesis. Prominent genetic heterogeneity is characteristic of both PIN and carcinoma; and multiple foci of PIN arise independently within the same prostate. This observation suggests that a field effect probably underlies prostatic neoplasia. Multiple foci of cancer also often arise independently, lending additional support to this hypothesis. The strong genetic similarities between PIN and cancer strongly suggest that evolution and clonal expansion of PIN, or other precursor lesions, may account for the multifocal etiology of carcinoma. Uncertainties with respect to identification of those precursor lesions which are most likely to progress to invasive and metastatic prostate cancer reinforce the requirement for objective immunohistochemical or molecular biological markers of the aggressive phenotype.

Molecular genetics of prostate cancer

The molecular mechanisms underlying the development and progression of prostate cancer are poorly understood. Epidemiological studies have suggested that 5-10% of all prostate cancers are familial, and numerous chromosomal loci have been associated with prostate cancer in multicentre linkage studies. However, no putative susceptibility genes harboured in these chromosomal regions have thus far been identified. Several recurrent chromosomal alterations in prostate cancer have been detected in comparative genomic hybridization (CGH) and loss of heterozygosity (LOH) analysis. The target genes for many of these aberrations are still not known. It seems that the androgen receptor (AR) signalling pathway plays a crucial role in both early development as well as in late progression of the disease. Both germ-line and somatic genetic alterations in the AR gene have been demonstrated in prostate cancer patients. The intention of this review is to summarize the current knowledge of molecular mechanisms in the development of prostate cancer.

Genetic linkage analysis of prostate cancer families to Xq27-28

OBJECTIVES

A recent linkage analysis of 360 families at high risk for prostate cancer identified the q27-28 region on chromosome X as the potential location of a gene involved in prostate cancer susceptibility. Here we report on linkage analysis at this putative HPCX locus in an independent set of 186 prostate cancer families participating in the Prostate Cancer Genetic Research Study (PROGRESS).

METHODS

DNA samples from these families were genotyped at 8 polymorphic markers spanning 14.3 cM of the HPCX region.

RESULTS

Two-point parametric analysis of the total data set resulted in positive lod scores at only two markers, DXS984 and DXS1193, with scores of 0.628 at a recombination fraction (theta) of 0.36 and 0.012 at theta = 0.48, respectively. The stratification of pedigrees according to the assumed mode of transmission increased the evidence of linkage at DXS984 in 81 families with no evidence of male-to-male transmission (lod = 1.062 at theta = 0.28).

CONCLUSIONS

Although this analysis did not show statistically significant evidence for the linkage of prostate cancer susceptibility to Xq27-28, the results are consistent with a small percentage of families being linked to this region. The analysis further highlights difficulties in replicating linkage results in an etiologically heterogeneous, complexly inherited disease.

Heterogeneity in genetic susceptibility to prostate cancer

The incidence of prostate cancer is related to aging. Its increase in the last 10 years, varies from country to country and according to ethnic group, with its greatest incidence among African-American males and the least among Asian males. Only two risk factors have thus far been clearly established for prostate cancer: familial aggregation and ethnic origin. No dietary or environmental cause has yet been identified for prostate cancer. However, some variations in endogenous factors, such as sex steroids or IGF1 circulating levels, may partly explain differences in risk observed between different populations. Genetic polymorphisms of genes encoding for 5alpha-reductase, androgen receptor, or vitamin D receptor have been associated with different degrees of risk for prostate cancer and may explain variations in risk among ethnic groups or within geographic areas. Different studies support the theory that familial prostate cancer may be hereditary and not due to a similar lifestyle. Thus, familial inheritance is a parameter that must be considered when advising screening in high-risk families. Indeed, the relative risk for first-degree relatives of prostate cancer patients can reach 2, 5 and 11 when, respectively, 1, 2 and 3 first-degree relatives are affected. Some familial forms appear to be associated with transmission of a rare, putative, autosomal dominant gene (0.003-0.06 allele frequency) with a high penetrance (88% at age 85). Using this transmission model and linkage analysis, three predisposing loci on chromosome 1: HPC-1 (hereditary prostate cancer 1: 1q24-25), PCaP (predisposing for prostate cancer: 1q42-43) and CAPB (predisposing for prostate and brain tumor: 1p36) and one locus on chromosome 20 (HPC20: 20q13) have been described. Moreover, X-linked transmission has been suggested and related to another predisposing gene locus: HPCX (Xq27-28). It is possible that a large proportion of familial prostate cancer is due not to segregation of a few major gene mutations transmitted according to a monogenic inheritance, but rather to familial sharing of alleles at many loci, each contributing to a small increase in cancer risk.

Prostate cancer genomics

The molecular processes contributing to cancer of the human prostate gland are under intensive investigation. Methods used for discovering genetic alterations involved in prostate neoplasia include family studies designed to map hereditary disease loci, chromosomal studies to identify aberrations that may locate oncogenes or tumor suppressor genes, and comprehensive gene expression studies. These studies determine how various molecular signaling pathways influence or reflect the process of carcinogenesis. However, a comprehensive overview of the cell is necessary to understand all of the dynamic interactions between genes, their protein products, and the network of cellular processes resulting in tumorigenesis. Unraveling the complexity of these systems in a timely manner involves the integration of computers, miniaturization, and automation into molecular biology. New biotechnologies such as the development of automated DNA sequencing and complementary DNA microarrays allow for a systematic, "discovery-driven" approach. These and other technologies afford a comprehensive view of biology and pathology that have the potential to fully characterize the processes involved in neoplasia and therefore provide potential targets for the therapy of prostate and other cancers.

PCAP is the major known prostate cancer predisposing locus in families from south and west Europe

To date four prostate cancer predisposing loci have been mapped: HPC1 (Hereditary Prostate Cancer 1) on 1q24-25, PCaP (Predisposing for Cancer Prostate) on 1q42.2-43, CAPB (Cancer Prostate and Brain) on 1p36, and HPCX on Xq27-28. We examined evidence for linkage to those loci in 64 families from south and west Europe. Genotyping of three (six for PCaP) markers encompassing the candidate regions were performed on 221 individuals including 159 affected patients. The resulting data were analysed using both parametric and non parametric linkage methods. No significant evidence of linkage to HPC1, CAPB, or HPCX was found either in the whole population or when pedigrees were stratified according to criteria specific to each locus. By contrast, results in favour of linkage to PCaP locus were observed with maximum multipoint NPL and HLOD scores of 2.8 (P = 0.0026) and 2.65 respectively. Homogeneity analysis performed with multipoint LOD scores gave an estimated proportion of families with linkage to this locus up to 50%. Particularly, families with an earlier age at diagnosis (< or = 65-years-old) contributed significantly to the evidence of linkage with a maximum multipoint NPL score of 2.03 (P = 0.024). Those results suggest that PCaP is the most frequent known locus predisposing to hereditary prostate cancer cases from families from south and west Europe.

No evidence of linkage to chromosome 1q42.2-43 in 131 prostate cancer families from the ACTANE consortium. Anglo, Canada, Texas, Australia, Norway, EU Biomed

Genetic linkage studies worldwide have proposed various chromosomal localizations for prostate cancer susceptibility genes. A recent study found evidence for linkage to chromosome 1q42.2-43. The aim of our study was to attempt to confirm these findings by performing linkage analysis in 131 families with multiple prostate cancer cases selected from the ACTANE (Anglo, Canada, Texas, Australia, Norway, EU Biomed) Consortium. Parametric and non-parametric linkage (NPL) analyses were performed. Two-point LOD scores failed to show evidence of linkage at any marker (maximum two-point LOD score = 0. 40 at recombination fraction theta = 0.2 with marker D1S2850). Using a multipoint heterogeneity analysis, the estimated proportion of families linked to this putative locus (alpha) was 0% (95% CI = 0. 00-0.33). Non-parametric linkage analysis also found no evidence of linkage (maximum NPL score = -0.12, P = 0.55). This analysis of 131 ACTANE families does not support the presence of a locus for a prostate cancer susceptibility gene at 1q42.2-43. Although we cannot rule out the existence of such a locus, analysis indicates that less than 16% of families could be linked to this region. These findings may be a reflection of the locus heterogeneity involved in this disease indicating that there are still other major susceptibility loci to be identified.