A candidate prostate cancer susceptibility gene at chromosome 17p

Characterization of an Escherichia coli elaC deletion mutant

The elaC gene of Escherichia coli encodes a binuclear zinc phosphodiesterase (ZiPD). ZiPD homologs from various species act as3' tRNA processing endoribonucleases, and although the homologous gene in Bacillus subtilis is essential for viability [EMBO J. 22(2003) 4534], the physiological function of E. coli ZiPD has remained enigmatic. In order to investigate the function of E. coli ZiPDwe generated and characterized an E. coli elaC deletion mutant. Surprisingly, the E. coli elaC deletion mutant was viable and had wild-type like growth properties. Microarray-based transcriptional analysis indicated expression of the E. coli elaC gene at basal levels during aerobic growth. The elaC gene deletion had no effect on the expression of genes coding for RNases or amino-acyl tRNA synthetases or any other gene among a total of > 1300 genes probed. 2D-PAGE analysis showed that the elaC mutation, like-wise, had no effect on the proteome. These results strengthen doubts about the involvement of E. coli ZiPD in tRNA maturation and suggest functional diversity within the ZiPD/ElaC1 protein family. In addition to these unexpected features of the E. coli elaC deletion mutant, a sequence comparison of ZiPD (ElaC1) proteins revealed specific regions for either enterobacterial or mammalian ZiPD (ElaC1) proteins.

Genetic alterations in prostate cancer

Prostate cancer is the number one malignancy among men. The search for causative factors has proven to be difficult and, accordingly, treatment options for advanced prostate cancer remain limited. However, technologic breakthroughs in the fields of genetics and molecular biology have advanced our understanding of the mechanisms involved in prostate carcinogenesis. The aim of this article is to review the most recent evidence for the role of various genetic insults at specific steps in tumor formation and to suggest potential therapeutic targets.

Combined genome-wide scan for prostate cancer susceptibility genes

BACKGROUND

Prostate cancer represents a substantial public health burden worldwide. It is the second leading cause of cancer death among men in the United States. A family history of the disease is among the most well-established risk factors for prostate cancer. Efforts to localize prostate cancer susceptibility alleles by using genetic linkage analysis methods have been hindered by genetic heterogeneity, incomplete penetrance, disease phenocopies, and the lack of DNA samples from parents of individuals with late-onset prostate cancer.

METHODS

We performed a combined genome-wide linkage analysis among 426 families from four existing hereditary prostate cancer (HPC) study populations to systematically search for prostate cancer susceptibility genes. To decrease the degree of locus heterogeneity, we analyzed subsets of families with similar clinical and demographic characteristics. Nonparametric multipoint linkage was the primary method of analysis. Results are presented as allele-sharing logarithm of the odds (LOD) scores, and all reported P values are two-sided.

RESULTS

The strongest evidence for prostate cancer linkage was found at chromosome region 17q22 (nonparametric multipoint Kong and Cox allele-sharing LOD score = 3.16 at marker D17S787; P =.00007). Stratified analyses revealed several additional chromosomal regions that are likely to segregate prostate cancer susceptibility genes among specific subsets of HPC families, including 15q11 among families with late-onset disease (allele-sharing LOD = 5.57 at marker D15S128; P<.00001) and 4q35 among families with four or more affected family members (allele-sharing LOD = 3.10 at marker D4S1615; P =.00008).

CONCLUSION

Fine mapping studies to facilitate identification of prostate cancer susceptibility genes in these linked regions are warranted.

Structure of primate and rodent orthologs of the prostate cancer susceptibility gene ELAC2

The human ELAC2 gene was the first candidate prostate cancer susceptibility gene identified by linkage analysis and positional cloning. DNA sequence indicates a protein of 826 amino acids encoded by 24 exons. In the present study, we characterized the coding sequence of chimpanzee and gorilla ELAC2 orthologs by direct sequencing of genomic fragments, and of cynomolgus monkey and rat orthologs by screening cDNA libraries. The orthologs characterized in the chimpanzee, gorilla and cynomolgus monkey also encode proteins of 826 amino acids, sharing 98.9%, 98.5% and 93.7% sequence identity with the human protein. Our analyses of the mouse ELAC2 gene identified two alternative mRNA transcripts. One is translated into a protein of 824 a.a. (mouse ELAC2), whereas the other one encodes a protein of 831 amino acids (mouse ELAC2A) resulting from an alternatively spliced form of 25 exons. The rat ELAC2 gene ortholog also expressed two similar alternatively spliced transcripts. These two forms are ubiquitously expressed in mouse and rat tissues. The highest levels of expression of the ELAC2 form are observed in the testis while the lowest levels are seen in the prostate and in the muscle. However, it is of interest to note that the relative abundance of the rat and mouse ELAC2 transcripts, measured by real-time quantitative PCR, is higher than the respective ELAC2A forms in all surveyed tissues except for the prostate and the muscle. The ELAC2A transcript levels are 4.1 to 5.0-fold higher than the ELAC2 levels in the prostate of rat and mouse, respectively. A fine analysis of the conserved domains on the primary structure of ELAC2 orthologs revealed the presence of a putative beta-CASP domain shared by the PSO2 (SNM1) DNA interstrand cross-link repair proteins, and the 73-kDa subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73) as well as Artemis proteins, thus suggesting a potential interaction of ELAC2 gene product with nucleic acids and more specifically with RNA targets. Taken together, these data offer useful tools to further study the regulation and cellular function of ELAC2 gene in experimental models and provide further insight concerning conserved amino acid motifs that could have biological significance.

The N-terminal half-domain of the long form of tRNase Z is required for the RNase 65 activity

Transfer RNA (tRNA) 3' processing endoribonuclease (tRNase Z) is an enzyme responsible for the removal of a 3' trailer from pre-tRNA. There exists two types of tRNase Z: one is a short form (tRNase ZS) that consists of 300-400 amino acids, and the other is a long form (tRNase ZL) that contains 800-900 amino acids. Here we investigated whether the short and long forms have different preferences for various RNA substrates. We examined three recombinant tRNase ZSs from human, Escherichia coli and Thermotoga maritima, two recombinant tRNase ZLs from human and Saccharomyces cerevisiae, one tRNase ZL from pig liver, and the N- and C-terminal half regions of human tRNase ZL for cleavage of human micro-pre-tRNA(Arg) and the RNase 65 activity. All tRNase ZLs cleaved the micro-pre-tRNA and showed the RNase 65 activity, while all tRNase ZSs and both half regions of human tRNase ZL failed to do so with the exception of the C-terminal half, which barely cleaved the micro-pre-tRNA. We also show that only the long forms of tRNase Z can specifically cleave a target RNA under the direction of a new type of small guide RNA, hook RNA. These results indicate that indeed tRNase ZL and tRNase ZS have different substrate specificities and that the differences are attributed to the N-terminal half-domain of tRNase ZL. Furthermore, the optimal concentrations of NaCl, MgCl2 and MnCl2 differed between tRNase ZSs and tRNase ZLs, and the K(m) values implied that tRNase ZLs interact with pre-tRNA substrates more strongly than tRNase ZSs.

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.

A novel 4-base-recognizing RNA cutter that can remove the single 3' terminal nucleotides from RNA molecules

Mammalian tRNase ZL shows versatility in substrate recognition. This enzyme can not only process pre-tRNAs by cleaving off their 3' trailer sequences, but also recognize and cleave pre-tRNA-like complexes and micro-pre-tRNAs. Here we demonstrate that 24-27 nt hairpin RNAs (hook RNAs) can guide cleavages of separate target RNAs by tRNase ZL through the micro-pre-tRNA-like complexes between the targets and the hook RNAs and that tRNase ZL together with hook RNA works as 4-7-base-recognizing RNA cutters. The cleavage sites were located only after the nucleotide corresponding to the discriminator nucleotide. Cleavage assays for various substrate/hooker complexes showed that the cleavage efficiency changes depending on the maximum number of substrate/hooker recognition base pairings and the stem length of hook RNA and that a 5 nt recognition sequence and a hook RNA containing a 6 or 7 bp stem are the best combination for the optimal target cleavage. We also show that a 4-base RNA cutter can remove the single 3' terminal nucleotides from RNA molecules. These results indicate that this new type of RNA cutter can be utilized to homogenize at their 3' termini RNA transcripts synthesized in vitro with a bacteriophage RNA polymerase.

A novel founder CHEK2 mutation is associated with increased prostate cancer risk

Variants in the CHEK2 have been found to be associated with prostate cancer risk in the United States and Finland. We sequenced CHEK2 gene in 140 Polish patients with prostate cancer and then genotyped the three detected variants in a larger series of prostate cancer cases and controls. CHEK2 truncating mutations (IVS2 + 1G>A or 1100delC) were identified in 9 of 1921 controls (0.5%) and in 11 of 690 (1.6%) unselected patients with prostate cancer [odds ratio (OR) = 3.4; P = 0.004]. These mutations were found in 4 of 98 familial prostate cases (OR = 9.0; P = 0.0002). The missense variant I157T was also more frequent in men with prostate cancer (7.8%) than in controls (4.8%), but the relative risk was more modest (OR = 1.7; P = 0.03). I157T was identified in 16% of men with familial prostate cancer (OR = 3.8; P = 0.00002). Loss of the wild-type CHEK2 allele was not observed in any of prostate cancers from five men who carried CHEK2-truncating mutations. Our results provide evidence that the two truncating mutations of CHEK2 confer a moderate risk of prostate cancer in Polish men and that the missense change appears to confer a modest risk.

Graphical modeling of the joint distribution of alleles at associated loci

Pairwise linkage disequilibrium, haplotype blocks, and recombination hotspots provide only a partial description of the patterns of dependences and independences between the allelic states at proximal loci. On the gross scale, where recombination and spatial relationships dominate, the associations can be reasonably described in these terms. However, on the fine scale of current high-density maps, the mutation process is also important and creates associations between loci that are independent of the physical ordering and that can not be summarized with pairwise measures of association. Graphical modeling provides a standard statistical framework for characterizing precisely these sorts of complex stochastic data. Although graphical models are often used in situations in which assumptions lead naturally to specific models, it is less well known that estimation of graphical models is also a developed field. We show how decomposable graphical models can be fitted to dense genetic data. The objective function is the maximized log likelihood for the model penalized by a multiple of the model's degrees of freedom. We also describe how this can be modified to incorporate prior information of locus position. Simulated annealing is used to find good solutions. Part of the appeal of this approach is that categorical phenotypes can be included in the same analysis and association with polymorphisms can be assessed jointly with the interlocus associations. We illustrate our method with genotypic data from 25 loci in the ELAC2 gene. The results contain third- and fourth-order locus interactions and show that, at this density of markers, linkage disequilibrium is not a simple function of physical distance. Graphical models provide more flexibility to express these features of the joint distribution of alleles than do monotonic functions connecting physical and genetic maps.

Molecular Mechanisms of Prostate Cancer

During the last ten years our knowledge of genetic alterations in prostate cancer has significantly increased. For example, several chromosomal loci possibly harboring predisposing or somatically mutated genes have been suggested. Still, we lack the comprehensive molecular model for the development and progression of prostate cancer. Only a few genes have been found to be aberrant in a significant proportion of prostate cancer. These include GSTP1, PTEN, TP53, and AR. Thus, they are natural targets for new treatment strategies.

Identification of a human endonuclease complex reveals a link between tRNA splicing and pre-mRNA 3' end formation

tRNA splicing is a fundamental process required for cell growth and division. The first step in tRNA splicing is the removal of introns catalyzed in yeast by the tRNA splicing endonuclease. The enzyme responsible for intron removal in mammalian cells is unknown. We present the identification and characterization of the human tRNA splicing endonuclease. This enzyme consists of HsSen2, HsSen34, HsSen15, and HsSen54, homologs of the yeast tRNA endonuclease subunits. Additionally, we identified an alternatively spliced isoform of SEN2 that is part of a complex with unique RNA endonuclease activity. Surprisingly, both human endonuclease complexes are associated with pre-mRNA 3' end processing factors. Furthermore, siRNA-mediated depletion of SEN2 exhibited defects in maturation of both pre-tRNA and pre-mRNA. These findings demonstrate a link between pre-tRNA splicing and pre-mRNA 3' end formation, suggesting that the endonuclease subunits function in multiple RNA-processing events.

Analysis of the macrophage scavenger receptor 1 gene in Swedish hereditary and sporadic prostate cancer

BACKGROUND

The macrophage scavenger receptor 1 (MSR1) gene on chromosome 8p22 was recently reported as a candidate gene for hereditary prostate cancer (HPC). Here, we further elucidate the role of MSR1 in both Swedish families with HPC and in a cohort of unselected prostate cancer.

METHODS

DNA samples from 83 Swedish HPC families and 215 unselected population based cases of prostate cancer as well as 425 age-matched controls were genotyped.

RESULTS

A total of 18 variants were identified, including 2 exonic, 7 intronic changes, and 9 changes in the 5'- or 3'-uncoding region. Of the two exonic changes, one previously reported truncation mutation was identified, a R293X nonsense mutation. This mutation was found in 2 of the 83 (2.4%) HPC families. The R293X mutation was found more frequently in men with PC (4.9%) than in unaffected men (2.7%), consistent with previous published results, however our results were not significant (P = 0.16). To additionally test for potential association of common sequence variants and increased risk for the disease, five common polymorphisms (PRO3, INDEL1, IVS5-57, P275A, INDEL7) were genotyped in the group of 215 prostate cancer cases and 425 age-matched controls. No association between any of the five common sequence variants and prostate cancer were found.

CONCLUSION

Our results suggest that mutations in MSR1 gene might play a role in prostate cancer susceptibility, particularly the R293X mutation. This study warrants further investigations of the role of MSR1 in prostate cancer etiology.

Environmental, genetic, and molecular features of prostate cancer

Prostate cancer is the sixth most common cancer in the world and the third leading cause of cancer in men. The increase in the understanding of prostate carcinogenesis over the past 15 years has helped to define crucial steps in the natural history of the disease, namely initiation and progression to androgen independence. This heterogeneous disease encompasses a range of environmental and familial factors, which provides strong support for the use of chemopreventive strategies. Most patients with advanced prostate cancer are treated with androgen-deprivation therapy, which leads to a striking regression of androgen-responsive cancer cells. A transition from an androgen-responsive to an androgen-unresponsive stage is seen during the clinical course in almost all patients with prostate cancer. This transition also signals a substantial worsening of prognosis. Here, we review the most important findings in prostate carcinogenesis and the molecular anomalies associated with the androgen-refractory stage.

A pathogenesis-associated mutation in human mitochondrial tRNALeu(UUR) leads to reduced 3'-end processing and CCA addition

Point mutations in mitochondrial tRNAs can cause severe multisystemic disorders such as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) and myoclonus epilepsy with ragged-red fibers (MERRF). Some of these mutations impair one or more steps of tRNA maturation and protein biosynthesis including 5'-end-processing, post-transcriptional base modification, structural stability, aminoacylation, and formation of tRNA-ribosomal complexes. tRNALeu(UUR), an etiologic hot spot for such diseases, harbors 20 of more than 90 disease-associated mutations described to date. Here, the pathogenesis-associated base substitutions A3243G, T3250C, T3271C, A3302G and C3303T within this tRNA were tested for their effects on endonucleolytic 3'-end processing and CCA addition at the tRNA 3'-terminus. Whereas mutations A3243G, A3302G and C3303T reduced the efficiency of 3'-end cleavage, only the C3303T substitution was a less efficient substrate for CCA addition. These results support the view that pathogenesis may be elicited through cumulative effects of tRNA mutations: a mutation can impede several pre-tRNA processing steps, with each such reduction contributing to the overall impairment of tRNA function.

Pharmacogenetics of human androgens and prostate cancer – an update

Prostate cancer is the most common non-skin cancer in the US; it is the second leading cause of death from cancer among US men, and the seventh leading cause of death in the US. This review examines the recent biochemical and pharmacogenetic literature related to prostate cancer, specifically that which focused on constitutional (‘germline’) single nucleotide polymorphisms at ‘functional candidate’ genes for prostate cancer. The investigations summarized in this review demonstrate the need to study the molecular genetics at these loci to rationally develop personalized medicine. In addition, the identification of somatic pharmacogenetic alterations in one of these loci suggests that this may also be a fruitful field of investigations with important clinical applications. Pharmacogenomic investigations of constitutional and tumor DNA may lead to significant advances in chemoprevention, presymptomatic diagnosis and improved treatment of prostate cancer.

Androgen receptor in prostate cancer

The normal development and maintenance of the prostate is dependent on androgen acting through the androgen receptor (AR). AR remains important in the development and progression of prostate cancer. AR expression is maintained throughout prostate cancer progression, and the majority of androgen-independent or hormone refractory prostate cancers express AR. Mutation of AR, especially mutations that result in a relaxation of AR ligand specificity, may contribute to the progression of prostate cancer and the failure of endocrine therapy by allowing AR transcriptional activation in response to antiandrogens or other endogenous hormones. Similarly, alterations in the relative expression of AR coregulators have been found to occur with prostate cancer progression and may contribute to differences in AR ligand specificity or transcriptional activity. Prostate cancer progression is also associated with increased growth factor production and an altered response to growth factors by prostate cancer cells. The kinase signal transduction cascades initiated by mitogenic growth factors modulate the transcriptional activity of AR and the interaction between AR and AR coactivators. The inhibition of AR activity through mechanisms in addition to androgen ablation, such as modulation of signal transduction pathways, may delay prostate cancer progression.

-160C/A polymorphism in the E-cadherin gene promoter and risk of hereditary, familial and sporadic prostate cancer

The E-cadherin (CDH1) gene has been associated with prostate carcinogenesis. The C/A polymorphism--160 base pairs relative to the transcription start site has been shown to decrease gene transcription. We analyzed the association between this polymorphism and the risk of sporadic, familial (2 close relatives) and hereditary (3 or more close relatives) prostate cancer. We combined data from 3 population-based epidemiologic studies in Sweden encompassing altogether 1,036 prostate cancer cases and 669 controls that were genotyped for the short nucleotide polymorphism. Odds ratios with 95% confidence intervals were estimated through unconditional logistic regression. We found no significant association between the A-allele and sporadic (OR = 1.0; 95% CI = 0.8-1.2) or familial (OR = 1.4; 95% CI = 0.9-2.2) prostate cancer. In contrast, risk of hereditary cancer was increased among heterozygote CA carriers (OR = 1.7; 95% CI = 1.0-2.7) and particularly among homozygote AA carriers (OR = 2.6; 95% CI = 1.4-4.9). Our data indicate that the -160 single nucleotide polymorphism in CDH1 is a low-penetrant prostate cancer susceptibility gene that might explain a proportion of familial and notably hereditary prostate cancer.

Molecular genetics of human prostate cancer

Multiple factors contribute to the high incidence and prevalence of prostate cancer including race, ethnicity, diet, environment, widespread awareness through prostate-specific antigen screening and genetics. Linkage analysis has identified several candidate sites for hereditary prostate cancer gene loci. Molecular studies have also identified genes that are frequently altered in sporadic prostate cancer. It appears that due to the heterogeneity of prostate cancer, multiple genes may be involved in the neoplastic process.

WITHDRAWN:Epidemiology of prostate cancer and its precursors

Ahead of Print article withdrawn by publisher.

Mutational analysis of susceptibility genes RNASEL/HPC1, ELAC2/HPC2, and MSR1 in sporadic prostate cancer

Three putative prostate cancer-susceptibility genes, RNASEL/HPC1 at 1q24, MSR1 at 8p22, and ELAC2/HPC2 at 17p11, have recently been identified. Our objective was to investigate somatic mutations in these genes in sporadic prostate cancer. We analyzed 39 clinical prostate cancer specimens, 10 prostate cancer xenografts (LuCaP series), and 4 prostate cancer cell lines (LNCaP, DU145, PC-3, and MPC-3) for genetic changes using denaturing high-performance liquid chromatography and direct sequencing in order to screen the whole coding regions of RNASEL and MSR1, as well as exons 7 and 17 of ELAC2. The known 471delAAAG truncating mutation was found in the RNASEL gene in cell line LNCaP. The only new missense variation in RNASEL, Gly296Val, was found in cell line DU145, but not in any other samples. RNASEL and ELAC2 also showed the common missense polymorphic changes. A previously reported truncating mutation (Arg293X) was found in MSR1 in the germ line of one individual. Our results indicate that inactivation of the RNASEL, ELAC2, or MSR1 genes by somatic mutation is a rare phenomenon in sporadic prostate cancer.

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.

NBS1 is a prostate cancer susceptibility gene

To evaluate whether an inactivating mutation in the gene for the Nijmegen breakage syndrome (NBS1) plays a role in the etiology of prostate cancer, we compared the prevalence of the 657del5 NBS1 founder allele in 56 patients with familial prostate cancer, 305 patients with nonfamilial prostate cancer, and 1500 control subjects from Poland. Loss of heterozygosity analysis also was performed on DNA samples isolated from 17 microdissected prostate cancers, including 8 from carriers of the 657del5 mutation. The NBS1 founder mutation was present in 5 of 56 (9%) patients with familial prostate cancer (odds ratio, 16; P < 0.0001), 7 of 305 (2.2%) patients with nonfamilial prostate cancer (odds ratio, 3.9; P = 0.01), and 9 of 1500 control subjects (0.6%). The wild-type NBS1 allele was lost in seven of eight prostate tumors from carriers of the 657del5 allele, but loss of heterozygosity was seen in only one of nine tumors from noncarriers (P = 0.003). These findings suggest that heterozygous carriers of the NBS1 founder mutation exhibit increased susceptibility to prostate cancer and that the cancers that develop in the prostates of carriers are functionally homozygous for the mutation.

Molecular pathways to prostate cancer

PURPOSE

Prostate cancer continues to be a prevalent disease in the United States and western countries. Advances in the fields of molecular biology and genetics coupled with new developments in biotechnology have increased our understanding of events associated with the initiation and progression of prostate cancer. We reviewed recent scientific discoveries relating to genetic predisposition, somatic alterations and epigenetic phenomena involved in the pathogenesis of prostate cancer.

MATERIALS AND METHODS

Reports published in the scientific literature with relevance to the molecular biology, genetics and epigenetics of prostate cancer were identified using the MEDLINE data base. Particular emphasis was placed on articles that investigated the contribution of somatic alterations to prostate cancer.

RESULTS

A multitude of genes have recently been identified that are believed to be relevant to prostate carcinogenesis. A contemporary model for prostate cancer progression should include the potential contribution of inflammation to the development of preneoplastic or neoplastic lesions. Abnormal methylation of important growth regulatory or caretaker genes represents an alternative pathway to cancer in addition to aneuploidy, loss of heterozygosity and gene mutations.

CONCLUSIONS

The identification of molecular markers specific to early and late events in prostate cancer progression is critical for the development of improved detection and prognostication strategies. While there is evidence to support the association between inflammation and prostate cancer, the exact mechanisms by which these processes occur are not well defined. The significant contribution of somatic and epigenetic defects to prostate carcinogenesis underscores the need to develop therapeutic approaches that specifically target these molecular alterations.

The Caenorhabditis elegans homolog of the putative prostate cancer susceptibility gene ELAC2, hoe-1, plays a role in germline proliferation

The potential prostate cancer susceptibility gene ELAC2 has a Caenorhabditis elegans homolog (which we call hoe-1, for homolog of ELAC2). We have explored the biological role of this gene using RNAi to reduce gene activity. We found that worms subjected to hoe-1 RNAi are slow-growing and sterile. The sterility results from a drastic reduction in germline proliferation and cell-cycle arrest of germline nuclei. We found that hoe-1 is required for hyperproliferation phenotypes seen with mutations in three different genes, suggesting hoe-1 may be generally required for germline proliferation. We also found that reduction of hoe-1 by RNAi suppresses the multivulva (Muv) phenotype resulting from activating mutations in ras and that this suppression is likely to be indirect. This is the first demonstration of a biological role for this class of proteins in a complex eukaryote and adds important information when considering the role of ELAC2 in prostate cancer.

A novel endonucleolytic mechanism to generate the CCA 3' termini of tRNA molecules in Thermotoga maritima

The tRNA 3'-terminal CCA sequence is essential for aminoacylation of the tRNAs and for translation on the ribosome. The tRNAs are transcribed as larger precursor molecules containing 5' and 3' extra sequences. In the tRNAs that do not have the encoded CCA, the 3' extra sequence after the discriminator nucleotide is usually cleaved off by the tRNA 3' processing endoribonuclease (3' tRNase, or RNase Z), and the 3'-terminal CCA residues are added thereto. Here we analyzed Thermotoga maritima 3' tRNase for enzymatic properties using various pre-tRNAs from T. maritima, in which all 46 tRNA genes encode CCA with only one exception. We found that the enzyme has the unprecedented activity that cleaves CCA-containing pre-tRNAs precisely after the CCA sequence, not after the discriminator. The assays for pre-tRNA variants suggest that the CA residues at nucleotides 75 and 76 are required for the enzyme to cleave pre-tRNAs after A at nucleotide 76 and that the cleavage occurs after nucleotide 75 if the sequence is not CA. Intriguingly, the pre-tRNA(Met) that is the only T. maritima pre-tRNA without the encoded CCA was cleaved after the discriminator. The kinetics data imply the existence of a CCA binding domain in T. maritima 3' tRNase. We also identified two amino acid residues critical for the cleavage site selection and several residues essential for the catalysis. Analysis of cleavage sites by 3' tRNases from another eubacteria Escherichia coli and two archaea Thermoplasma acidophilum and Pyrobaculum aerophilum corroborates the importance of the two amino acid residues for the cleavage site selection.

Drosophila RNase Z processes mitochondrial and nuclear pre-tRNA 3' ends in vivo

Although correct tRNA 3' ends are crucial for protein biosynthesis, generation of mature tRNA 3' ends in eukaryotes is poorly understood and has so far only been investigated in vitro. We report here for the first time that eukaryotic tRNA 3' end maturation is catalysed by the endonuclease RNase Z in vivo. Silencing of the JhI-1 gene (RNase Z homolog) in vivo with RNAi in Drosophila S2 cultured cells causes accumulation of nuclear and mitochondrial pre-tRNAs, suggesting that JhI-1 encodes both forms of the tRNA 3' endonuclease RNase Z, and establishing its biological role in endonucleolytic tRNA 3' end processing. In addition our data show that in vivo 5' processing of nuclear and mitochondrial pre-tRNAs occurs before 3' processing.

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.

Is there an association between multiple myeloma and prostate cancer?

In a series of 700 consecutive patients with prostate cancer, four patients were noted to have a history of multiple myeloma. An association between prostate cancer and multiple myeloma had not been previously described. An exploratory investigation of the biological basis of these two malignancies was undertaken to determine a possible mechanism for this association. A review of the genetic, molecular and chemical basis of prostate cancer and multiple myeloma development and progression is presented. A model suggesting the possible impact of immunosuppression from multiple myeloma and chemokines released by circulating myeloma cells including IGF-1, IL6, SDF1 and VEGF on the progression of prostate cancer to detectable stages is presented.

Site-specific familial aggregation of prostate cancer

Over the last decade, epidemiologic evidence has accumulated in favor of a significant but heterogeneous hereditary component in prostate cancer (PC) susceptibility. In order to map and clone PC susceptibility genes, stratification of PC families into genetically homogeneous groups appears to be a key issue. Subset definition based on age at diagnosis, presumed mode of inheritance, number of affecteds per family and coaggregation of PC with other cancers has already proven successful in some studies. Previously, the finding of the coaggregation of malignancies of the central nervous system within PC families helped to link a prostate-brain cancer susceptibility gene (CAPB) to chromosome 1p36. In this study, we evaluate the risk of PC and malignancies at other sites among first-degree relatives of a large population-based group of Dutch PC patients. A population-based family case-control study was initiated that included Caucasian PC patients newly diagnosed between July 1996 and December 1999. Information on 12,575 first-degree relatives of 704 PC patients and 1,371 controls was collected through postal questionnaires and telephone interviews. All reported PC in first-degree relatives was verified through medical records. In our population, PC has a strong familial component that is reflected by a 2.9-fold increased risk (95% CI = 2.2-3.9) of PC for first-degree relatives of PC patients. This familial risk was somewhat higher among brothers (hazard ratio = 3.9; 95% CI = 2.4-6.4) compared to fathers (hazard ratio = 2.5; 95% CI = 1.7-3.6). Cancers at other sites did not coaggregate with PC. Our data suggest that familial PC, at least in this Western European population, is site-specific, not part of an inherited cancer syndrome.

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.

Relative risk of prostate cancer for men with affected relatives: systematic review and meta-analysis

An increased risk of prostate cancer associated with a family history of prostate cancer has been documented in multiple published reports. Risk has been shown to vary by degree of relationship and age of onset of disease in the affected relative. Several studies, using various designs, have estimated the relative risk (RR) for these associations. The purpose of our study was to identify and summarize published reports on the relationship between risk of prostate cancer and family history, which is defined as having a father, brother, any first- or second-degree relative or other relative affected with prostate cancer. A Medline and manual search from 1982 to 2000 identified 24 studies that reported RR and confidence intervals (CI) and satisfied inclusion criteria. Pooled RR estimates based upon a weighted average model were as follows: any affected family member RR = 1.93, CI 1.65-2.26; affected first-degree relative RR = 2.22, CI 2.06-2.40; affected second-degree relative RR = 1.88, CI 1.54-2.30; father with prostate cancer RR = 2.12, CI 1.82-2.51; and brother with prostate cancer RR = 2.87, CI 2.21-3.73). Statistical comparison of pooled data demonstrated that the RR is significantly higher for affected brother than for affected father (p < 0.03). A sensitivity analysis demonstrated that these results are robust with respect to population bias. This meta-analysis confirms that risk of prostate cancer is associated with family history of disease and improves the quantification of this risk.

Genomewide linkage analysis of familial prostate cancer in the Japanese population

Prostate cancer (PC) is one of the most common causes of cancer mortality in Western countries, and familial aggregation of PC is well known. Multiple PC susceptibility loci have been reported in Western countries, but attempts to confirm the loci in independent data sets have proven to be inconsistent. We performed a genomewide linkage analysis with 53 affected sib pairs to identify genetic loci related to PC in a Japanese population. Two linkage analyses, GENEHUNTER-PLUS and SIBPAL, were applied and detected nominal statistical significance of linkage to PC at chromosome 1p and 8p, which were reported as being loci for PC in Caucasians. The best evidence of linkage was detected near D8S550 on 8p23 (maximum Zlr=2.25, P=0.037), and the second-best evidence of linkage was observed near D1S2667 on 1p36 (maximum Zlr=2.24, P=0.034). This is the first genetic mapping of PC in Japanese, and the results suggest that susceptibilities to PC lie close to D8S550 on 8p23 and D1S2667 on 1p36.

Genome-wide scan for prostate cancer susceptibility genes using families from the University of Michigan prostate cancer genetics project finds evidence for linkage on chromosome 17 near BRCA1

BACKGROUND

Previous linkage studies have suggested prostate cancer susceptibility genes located on chromosomes 1, 20, and X. Several putative prostate cancer candidate genes have also been identified including RNASEL, MSR1, and ELAC2. Presently, these linkage regions and candidate genes appear to explain only a small proportion of hereditary prostate cancer cases suggesting the need for additional whole genome analyses.

METHODS

A genome-wide mode-of-inheritance-free linkage scan, using 405 genetic markers, was conducted on 175 pedigrees, the majority containing three or more affected individuals diagnosed with prostate cancer. Stratified linkage analyses were performed based on previously established criteria.

RESULTS

Results based on the entire set of 175 pedigrees showed strong suggestive evidence for linkage on chromosome 17q (LOD = 2.36), with strongest evidence coming from the subset of pedigrees with four or more affected individuals (LOD = 3.27). Race specific analyses revealed strong suggestive evidence for linkage in our African-American pedigrees on chromosome 22q (LOD = 2.35).

CONCLUSIONS

Genome-wide analysis of a large set of prostate cancer families indicates new areas of the genome that may harbor prostate cancer susceptibility genes. Specifically, our linkage results suggest that there is a prostate cancer susceptibility gene on chromosome 17 that is independent of ELAC2. Further research including combined analyses of independent genome-wide scan data may clarify the most important regions for future investigation.

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.

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-wide scan of brothers: replication and fine mapping of prostate cancer susceptibility and aggressiveness loci

BACKGROUND

Substantial evidence suggests that genetic factors play an important role in both the risk of prostate cancer and its biologic aggressiveness. Here we investigate prostate cancer susceptibility and aggressiveness with genome-wide linkage analyses of affected brothers.

METHODS

We first undertook a new genome-wide linkage study of 259 brothers with prostate cancer. Our analyses tested whether the proportion of marker alleles shared by brothers was correlated with disease status or Gleason score. To further clarify 11 linkage regions observed here or previously, we genotyped and analyzed an additional 101 finely spaced markers in the 259 men, and in 594 previously studied brothers, allowing for a pooled genome-wide analysis of 853 affected brothers.

RESULTS

In the new study, we detected linkage to prostate cancer on chromosome 16q23 (P = 0.009), replicating previous results, and to chromosome 11q24 (P = 0.001). In the pooled analysis, the 16q23 linkage was strengthened (P = 0.0005), as was our previous linkage to chromosome 16p (P = 0.0001), and we detected linkage to chromosome 2q32 (P = 0.009). When evaluating Gleason score, our new study detected linkage to chromosome 7q32 (P = 0.0009), again replicating previous results, and to chromosomes 5p15 (P = 0.003), 9q34 (P = 0.009), 10q26 (P = 0.03), and 18p11 (P = 0.02). In the pooled analysis of Gleason score, we observed stronger linkage to chromosome 7q32 (P = 0.0002), but slightly weaker linkage to chromosomes 5q33 (P = 0.005) and 19q13 (P = 0.009) than previously reported. In addition, the new linkages to chromosomes 10q26 and 18p11 were strengthened (P = 0.0002 and P = 0.002, respectively).

CONCLUSIONS

Our results provide compelling evidence for loci harboring prostate cancer susceptibility and tumor aggressiveness genes, especially on chromosomes 16q23 and 7q32.

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.

Inference on haplotype effects in case-control studies using unphased genotype data

A variety of statistical methods exist for detecting haplotype-disease association through use of genetic data from a case-control study. Since such data often consist of unphased genotypes (resulting in haplotype ambiguity), such statistical methods typically apply the expectation-maximization (EM) algorithm for inference. However, the majority of these methods fail to perform inference on the effect of particular haplotypes or haplotype features on disease risk. Since such inference is valuable, we develop a retrospective likelihood for estimating and testing the effects of specific features of single-nucleotide polymorphism (SNP)-based haplotypes on disease risk using unphased genotype data from a case-control study. Our proposed method has a flexible structure that allows, among other choices, modeling of multiplicative, dominant, and recessive effects of specific haplotype features on disease risk. In addition, our method relaxes the requirement of Hardy-Weinberg equilibrium of haplotype frequencies in case subjects, which is typically required of EM-based haplotype methods. Also, our method easily accommodates missing SNP information. Finally, our method allows for asymptotic, permutation-based, or bootstrap inference. We apply our method to case-control SNP genotype data from the Finland-United States Investigation of Non-Insulin-Dependent Diabetes Mellitus (FUSION) Genetics study and identify two haplotypes that appear to be significantly associated with type 2 diabetes. Using the FUSION data, we assess the accuracy of asymptotic P values by comparing them with P values obtained from a permutation procedure. We also assess the accuracy of asymptotic confidence intervals for relative-risk parameters for haplotype effects, by a simulation study based on the FUSION data.

Genome-wide scan for linkage in finnish hereditary prostate cancer (HPC) families identifies novel susceptibility loci at 11q14 and 3p25-26

BACKGROUND

In order to identify predisposition loci to hereditary prostate cancer (HPC), we performed a genome-wide linkage analysis using samples from a genetically homogeneous population, with 13 Finnish multiplex prostate cancer families.

METHODS

Altogether 87 DNA samples were genotyped from 13 families. Logarithm-of-odds (LOD) scores were calculated for all autosomes using FASTLINK and GENEHUNTER designating all unaffected men and all women as unknown.

RESULTS

The highest LOD scores in the affected-only analyses were found at 11q14, where the two-point LOD score was 2.97 (theta = 0.0 at D11S901), GENEHUNTER heterogeneity LOD (HLOD) of 3.36, and a non-parametric-linkage (NPL) score of 2.67 (P = 0.008). A second positive site was at 3p25-26, with a two-point LOD score of 2.57 (theta = 0.01 at D3S1297), HLOD of 2.15, and NPL score of 2.27 (P = 0.02).

CONCLUSIONS

The results suggest two HPC regions in the Finnish population, which have not been reported previously and warrant further study.

Genome-wide scan for prostate cancer susceptibility genes in the Johns Hopkins hereditary prostate cancer families

BACKGROUND

Although the subject of intensive study, the genetic influences responsible for familial clustering of prostate cancer remain largely unidentified. Genome-wide scans for linkage in prostate cancer families can be used to systematically search for genes capable of affecting risk for the disease.

METHODS

All available family members from 188 families, each having at least three first-degree relatives affected with prostate cancer, were genotyped at 406 markers distributed across the genome at average intervals of less than 10 cM. Genotype data was analyzed using primarily a non-parametric, multipoint approach, although parametric analyses were performed as well.

RESULTS

The strongest evidence for linkage was observed at D4S1615, at 4q21 (LOD of 2.8, P = 0.0002). Two other regions had LOD scores over 2.0: at 9q34 (marker D9S1826, LOD = 2.17, P = 0.0008) and at 2q23 (marker D2S151, LOD = 2.03, P = 0.001). An additional 12 regions had LOD scores over 1.0, including markers at 1q24-25 and 7q22 having scores >1.6. Stratifying the linkage results by age of diagnosis indicated that the linkages to chromosomes 2 and 4 were strongest in families with early and late ages of diagnosis, respectively.

CONCLUSIONS

Our data implicate several new loci as harboring prostate cancer susceptibility genes, and provide confirmatory evidence of linkage at several loci identified previously in other genome-wide scans, including the three regions (4q21, 9q34, and 2q23) with strongest evidence for prostate cancer linkage. These data also emphasize the need to combine linkage data from large numbers of prostate cancer families in efforts to effectively address the extensive heterogeneity that characterizes genetic aspects of this disease.

HPC2/ELAC2 gene variants associated with incident prostate cancer

The HPC2/ELAC2 gene on chromosome 17p11 was identified as a candidate gene for hereditary prostate cancer (HPC) susceptibility. Two HPC2 gene missense variants, Ser217Leu (Leu217) and Ala541Thr (Thr541) have been associated with incident prostate cancer cases in some studies, but not in others. We tested for possible associations between the two HPC2 gene variants and prostate cancer risk in incident prostate cancer cases (199) and healthy male controls (525) from the Calgary region. The Thr541 variant showed linkage disequilibrium with the Leu217 variant. The number of Leu217 homozygotes in the case and control groups (8.6 versus 8.5%) was not statistically different. Leu217 carrier status was associated with prostate cancer risk (cases 61.8% versus controls 50.3%) (OR 1.6, 95% CI 1.15-2.23). Additional analysis found that this association was not due to the co-existence of Thr541 variant (OR1.59, P=0.009). Logistic regression found that the relationship between the log odds of being a Thr541carrier and age depends on case/control status. Thr541 carriers had an increased risk for late-onset prostate cancer (P=0.028). Prostate intraepithelial neoplasia (PIN) was more common in the Leu217 allele carriers compared to non-carriers (42.3 versus 26.7%) (OR 2.05, 95% CI 1.10-3.83), and in the Thr541 carriers compared to non-carriers (50.0 versus 34.6%) (OR 1.89, 95% CI 0.75-4.78). In summary, the HPC2 gene variants Leu217 and Thr541 were associated with an increased risk for prostate cancer and for PIN in males undergoing radical prostatectomies in the Calgary region.

A genealogical assessment of heritable predisposition to aneurysms

OBJECT

This study was conducted to investigate the familial and genetic contribution to intracranial, abdominal aortic, and all other types of aneurysms, and to define familial relationships among patients who present with the different aneurysm types.

METHODS

The authors used a unique Utah resource to perform population-based analysis of the familial nature of aneurysms. The Utah Population Data Base is a genealogy of the Utah population dating back eight generations, which is combined with death certificate data for the state of Utah dating back to 1904. Taking into account the genetic relationships among all aneurysm cases derived from this resource, the authors used a previously published method to estimate the familiality of different aneurysm types. Using internal, birth-cohort-specific rates of disease calculated from the database, they estimated relative risks by comparing observed to expected rates of aneurysm incidence in defined sets of relatives of probands.

CONCLUSIONS

Each of the three aneurysm types investigated showed significant evidence for a genetic component. Relatives of patients with intracranial aneurysms do not appear to be at increased risk for abdominal or other lesions, but relatives of patients with abdominal aortic aneurysms appear to be at increased risk for other types of these lesions.

Germline mutations in fumarate hydratase (FH) do not predispose to prostate cancer

Inherited susceptibility to prostate cancer has been linked to a number of chromosomal regions, however no genes have been unequivocally shown to underlie reported linkages. The putative gene localised to chromosome 1q42-q43, has been designated PCaP. We have recently shown that germline mutations in the fumarate hydratase (FH) gene located on 1q43 cause smooth muscle tumours and renal cell carcinoma. It is conceivable that germline FH mutations might confer an increased risk of prostate cancer and underlie linkage of prostate cancer to PCaP. To examine this proposition we have analysed the entire coding region of FH in 160 prostate cancer cases in 77 multiple case families. No pathogenic mutations in FH were identified in any of the cases. This data makes it highly unlikely that mutations in FH confer susceptibility to prostate cancer.

Ser217Leu polymorphism of the HPC2/ELAC2 gene associated with prostatic cancer risk in Japanese men

The HPC2/ELAC2 gene may be associated with hereditary/familial prostate cancer (PCa). Two common missense variants (Ser217Leu and Ala541Thr) have been reported in the gene. We performed mutational, allelotyping and expression analyses and a molecular epidemiological study to clarify the relations between this gene and prostatic diseases, including PCa and benign prostatic hyperplasia (BPH) in Japanese men. We screened for mutations in 109 patients with PCa including 11 patients from 1 hereditary and 9 familial PCa. Loss of heterozygosity and expression were analyzed. An epidemiological study was done in sporadic PCa (n=98) and BPH (n=143) using 1 novel (Ser627Leu) and 2 previously described polymorphisms of the HPC2/ELAC2 gene. Somatic or germline mutations were not confirmed in any cases of PCa. Loss of heterozygosity at 2 microsatellites, D17S1289 and D17S520, was detected in 1 of 38 and 1 of 35 cases, respectively. Expression analysis revealed decreased or absent mRNA expression in 6 of 38 tumors. Epidemiologic analysis showed that a Leu allele at codon 217 was significantly more frequent in patients with PCa than in controls (10.2% vs. 3.5%, odds ratio = 3.11; 95% confidence interval, 1.22-7.90). At codon 541, all patients with PCa or BPH and all control subjects had the Ala/Ala genotype. At codon 627, the incidence of the Leu variant was slightly, but not significantly, higher in patients with BPH than in controls (7.0% vs. 2.8%, odds ratio = 2.59, 95% confidence interval, 0.94-7.13, not statistically significant). We concluded that germline/somatic mutations of HPC2/ELAC2 are uncommon in PCa. Similarly, allelic imbalances at the gene locus and changes in expression are rare. Although no difference in allele frequency at Ser217Leu between patients with PCa and controls has been reported in a Western population, this polymorphism is a potential indicator of PCa risk in Japanese men and it should be examined in other ethnic groups.

The molecular genetics of prostate cancer

The molecular genetics of prostate cancer, the second most common cause of cancer-related death in men, is poorly understood. Inherited factors are believed to account for 42% of the risk of prostate cancer, and although multiple chromosomal loci of susceptibility have been identified, the target genes for these loci have not been well defined. Its heterogeneous nature suggests that the predisposition to prostate cancer may involve multiple genes and variable phenotypic expression. Genes that have been found to play a role in progression of prostate cancer include GSTP1 and PTEN, as well as the androgen receptor (AR) gene. Evidence suggests that the AR signaling pathway can be activated by other ligands when androgen levels are low. Recent findings have also implicated Kruppel-like factor 6 (KFL6), E-cadherin, the p40 subunit of eukaryotic translation initiation factor (eIF3-p40), and Elongin C, but confirmatory evidence is required to clarify the roles of these factors. Technologic advances, such as complementary DNA and tissue microarrays, have facilitated identification of genetic alterations and investigations of their function, but improved tools for searching and analyzing genes are still needed.

Molecular Techniques and Prostate Cancer Diagnostic

Recent advances in molecular techniques have given the opportunity to assess genomic and proteomic alterations comprehensively and rapidly in routinely acquired tissue samples. In particular, new markers derived from qualitative and quantitative DNA, RNA, and protein analysis have provided additional objective information to supplant and extend the morphologic interpretations and have been increasingly integrated into the final surgical pathology diagnosis. In this review several recently developed molecular techniques are described and illustrated. The focus is on prostate cancer diagnostics, as an example of their application.

Family history of prostate cancer and relapse after definitive external beam radiation therapy

PURPOSE

The influence of family history on outcome after definitive therapy for prostate cancer has been disputed. One series reported increased relapse rates in men with a positive family history of prostate cancer treated with radical prostatectomy or radiation therapy, whereas others have reported no difference in outcome. We examined our series of patients treated with definitive external beam radiation therapy to determine if a positive family history for prostate cancer is associated with better or worse outcome.

METHODS AND MATERIALS

Family history information was available for 538 patients treated with radiation therapy for prostate cancer between 1983 and 2001. Prostate cancer in one or more first-degree relatives (father, brother, or son) was considered a positive family history. The endpoint of interest was time to prostate-specific antigen failure or initiation of hormonal therapy after radiation therapy.

RESULTS

Ninety-seven of 538 patients (18%) had a positive family history. There were no significant differences between the positive and negative family history groups. Family history had no effect on relapse-free survival rates in the entire cohort (p = 0.94) or in any subgroup. African American patients with a positive family history had significantly worse 5-year relapse-free survival rates, although there were few patients in this subgroup. Neither family history nor race was a statistically significant predictor of relapse in multivariate analysis; however, combined African American race and positive family history was associated with worse relapse-free survival rates.

CONCLUSIONS

In this large study of patients receiving definitive radiation therapy for localized prostate cancer, no relationship was found between positive first-degree family history of prostate cancer and relapse. The influence of family history on clinical outcome may be more understandable once the gene or genes responsible for hereditary prostate cancer are identified.

Genetic polymorphisms of estrogen receptor alpha,CYP19, catechol-O-methyltransferase are associated with familial prostate carcinoma risk in a Japanese population

BACKGROUND

Estrogen is one of the crucial hormones participating in the proliferation and carcinogenesis of the prostate glands. Genetic polymorphisms in the estrogen metabolism pathway might be involved in the risk of prostate carcinoma development. The authors evaluated the association between genetic polymorphisms in estrogen-related enzymes and receptors and the risk of developing familial prostate carcinoma.

METHODS

In the current study, 101 cases with prostate carcinoma whose first-degree relatives had prostate carcinoma and 114 healthy age and residence-matched male controls were enrolled. The genotypes of estrogen receptor (ER) alpha, aromatase (CYP19), and catechol-O-methyltransferase (COMT) genes were analyzed.

RESULTS

For single polymorphisms, a significant association of the T/T genotype of the PvuII site in the ER alpha gene (odds ratio [OR], 3.44; 95% confidence interval [CI], 1.97-5.99; P = 0.0028), and the C/T and T/T genotypes of the CYP19 gene (OR, 1.77; 95% CI, 1.02-3.09; P = 0.037) with prostate carcinoma risk, was observed. The G/A genotype of the COMT gene showed a weak tendency toward increased risk (OR, 1.48; 95% CI, 0.85-2.57; P = 0.18). Stratification of cases according to clinical stage and pathologic grade showed that the C/T and T/T genotypes of the CYP19 gene were associated significantly with high-grade carcinoma (OR, 2.59; 95% CI, 1.47-4.46; P = 0.048). The number of high-risk genotypes (the T/T in ER alpha, the C/T and T/T in CYP19, and the G/A in COMT) significantly increased the risk of developing prostate carcinoma (2 genotypes: OR, 3.00; 95% CI, 1.72-5.23; P = 0.008; 3 genotypes: OR, 6.30; 95% CI, 3.61-10.99; P = 0.002).

CONCLUSIONS

Genetic polymorphisms of genes in the estrogen metabolism pathway were associated significantly with familial prostate carcinoma risk. Single nucleotide polymorphisms of low-penetrance genes are targets for understanding the genetic susceptibility of familial prostate carcinoma.

Endonucleolytic processing of CCA-less tRNA precursors by RNase Z in Bacillus subtilis

In contrast to Escherichia coli, where the 3' ends of tRNAs are primarily generated by exoribonucleases, maturation of the 3' end of tRNAs is catalysed by an endoribonuclease, known as RNase Z (or 3' tRNase), in many eukaryotic and archaeal systems. RNase Z cleaves tRNA precursors 3' to the discriminator base. Here we show that this activity, previously unsuspected in bacteria, is encoded by the yqjK gene of Bacillus subtilis. Decreased yqjK expression leads to an accumulation of a population of B.subtilis tRNAs in vivo, none of which have a CCA motif encoded in their genes, and YqjK cleaves tRNA precursors with the same specificity as plant RNase Z in vitro. We have thus renamed the gene rnz. A CCA motif downstream of the discriminator base inhibits RNase Z activity in vitro, with most of the inhibition due to the first C residue. Lastly, tRNAs with long 5' extensions are poor substrates for cleavage, suggesting that for some tRNAs, processing of the 5' end by RNase P may have to precede RNase Z cleavage.