Analysis of the RNASEL gene in familial and sporadic prostate cancer

Comparative Genomics Provides Insights into Adaptive Evolution and Demographics of Bats

Bats possess a range of distinctive characteristics, including flight, echolocation, impressive longevity, and the ability to harbor various zoonotic pathogens. Additionally, they account for the second-highest species diversity among mammalian orders, yet their phylogenetic relationships and demographic history remain underexplored. Here, we generated de novo assembled genomes for 17 bat species and 2 of their mammalian relatives (the Amur hedgehog and Chinese mole shrew), with 12 genomes reaching chromosome-level assembly. Comparative genomics and ChIP-seq assays identified newly gained genomic regions in bats potentially linked to the regulation of gene activity and expression. Notably, some antiviral infection-related gene under positive selection exhibited the activity of suppressing cancer, evidencing the linkage between virus tolerance and cancer resistance in bats. By integrating published bat genome assemblies, phylogenetic reconstruction established the proximity of noctilionoid bats to vesper bats. Interestingly, we found 2 distinct patterns of ancient population dynamics in bats and population changes since the last glacial maximum does not reflect species phylogenetic relationships. These findings enriched our understanding of adaptive mechanisms and demographic history of bats.

SET7/9-mediated methylation affects oncogenic functions of histone demethylase JMJD2A

The histone demethylase JMJD2A/KDM4A facilitates prostate cancer development, yet how JMJD2A function is regulated has remained elusive. Here, we demonstrate that SET7/9-mediated methylation on 6 lysine residues modulated JMJD2A. Joint mutation of these lysine residues suppressed JMJD2A's ability to stimulate the MMP1 matrix metallopeptidase promoter upon recruitment by the ETV1 transcription factor. Mutation of just 3 methylation sites (K505, K506, and K507) to arginine residues (3xR mutation) was sufficient to maximally reduce JMJD2A transcriptional activity and also decreased its binding to ETV1. Introduction of the 3xR mutation into DU145 prostate cancer cells reduced in vitro growth and invasion and also severely compromised tumorigenesis. Consistently, the 3xR genotype caused transcriptome changes related to cell proliferation and invasion pathways, including downregulation of MMP1 and the NPM3 nucleophosmin/nucleoplasmin gene. NPM3 downregulation phenocopied and its overexpression rescued, to a large degree, the 3xR mutation in DU145 cells, suggesting that NPM3 was a seminal downstream effector of methylated JMJD2A. Moreover, we found that NPM3 was overexpressed in prostate cancer and might be indicative of disease aggressiveness. SET7/9-mediated lysine methylation of JMJD2A may aggravate prostate tumorigenesis in a manner dependent on NPM3, implying that the SET7/9→JMJD2A→NPM3 axis could be targeted for therapy.

2-5A-Mediated decay (2-5AMD): from antiviral defense to control of host RNA

Mammalian cells are exquisitely sensitive to the presence of double-stranded RNA (dsRNA), a molecule that they interpret as a signal of viral presence requiring immediate attention. Upon sensing dsRNA cells activate the innate immune response, which involves transcriptional mechanisms driving inflammation and secretion of interferons (IFNs) and interferon-stimulated genes (ISGs), as well as synthesis of RNA-like signaling molecules comprised of three or more 2'-5'-linked adenylates (2-5As). 2-5As were discovered some forty years ago and described as IFN-induced inhibitors of protein synthesis. The efforts of many laboratories, aimed at elucidating the molecular mechanism and function of these mysterious RNA-like signaling oligonucleotides, revealed that 2-5A is a specific ligand for the kinase-family endonuclease RNase L. RNase L decays single-stranded RNA (ssRNA) from viruses and mRNAs (as well as other RNAs) from hosts in a process we proposed to call 2-5A-mediated decay (2-5AMD). During recent years it has become increasingly recognized that 2-5AMD is more than a blunt tool of viral RNA destruction, but a pathway deeply integrated into sensing and regulation of endogenous RNAs. Here we present an overview of recently emerged roles of 2-5AMD in host RNA regulation.

Carriage of mutations R462Q (rs 486907) and D541E (rs 627928) of the RNASEL gene and risk factors in patients with prostate cancer in Burkina Faso

Background

Prostate cancer (Pca) is a public health problem that affects men, usually of middle age or older. It is the second most common cancer diagnosed in men and the fifth leading cause of death. The RNASEL gene located in 1q25 and identified as a susceptibility gene to hereditary prostate cancer, has never been studied in relation to prostate cancer in Burkina Faso. The aim of this study was to analyze the carriage of RNASEL R462Q and D541E mutations and risks factors in patients with prostate cancer in the Burkina Faso.

Methods

This case–control study included of 38 histologically diagnosed prostate cancer cases and 53 controls (cases without prostate abnormalities). Real-time PCR genotyping of R462Q and D541E variants using the TaqMan® allelic discrimination technique was used. Correlations between different genotypes and combined genotypes were investigated.

Results

The R462Q variant was present in 5.3% of cases and 7.5% of controls. The D541E variant was present in 50.0% of cases and 35% of controls. There is no association between R462Q variants (OR = 0.60; 95%IC, 0.10–3.51; p = 0.686) and D541E variants (OR = 2.46; 95%IC, 0.78–7.80; p = 0.121) and genotypes combined with prostate cancer. However, there is a statistically significant difference in the distribution of cases according to the PSA rate at diagnosis (p ˂ 0.001). For the Gleason score distribution, only 13.2% of cases have a Gleason score greater than 7. There is a statistically significant difference in the Gleason score distribution of cases (p ˂ 0.001).

Conclusions

These variants, considered in isolation or in combination, are not associated with the risk of prostate cancer.

Activation of the antiviral factor RNase L triggers translation of non-coding mRNA sequences

Ribonuclease L (RNase L) is activated as part of the innate immune response and plays an important role in the clearance of viral infections. When activated, it endonucleolytically cleaves both viral and host RNAs, leading to a global reduction in protein synthesis. However, it remains unknown how widespread RNA decay, and consequent changes in the translatome, promote the elimination of viruses. To study how this altered transcriptome is translated, we assayed the global distribution of ribosomes in RNase L activated human cells with ribosome profiling. We found that RNase L activation leads to a substantial increase in the fraction of translating ribosomes in ORFs internal to coding sequences (iORFs) and ORFs within 5' and 3' UTRs (uORFs and dORFs). Translation of these alternative ORFs was dependent on RNase L's cleavage activity, suggesting that mRNA decay fragments are translated to produce short peptides that may be important for antiviral activity.

Evidence from 40 Studies that 2 Common Single-Nucleotide Polymorphisms (SNPs) of RNASEL Gene Affect Prostate Cancer Susceptibility: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-Compliant Meta-Analysis

BACKGROUND Numerous studies have evaluated the relationship between RNASEL gene polymorphisms (rs486907 G>A and rs627928 T>G) and the risk of cancer. However, many of the results have been controversial. To explore the role of RNASEL gene polymorphisms in prostate cancer, we carried out the present meta-analysis. MATERIAL AND METHODS The qualified articles were collected from PubMed, Web of Science, Scopus, CNKI, and WanFang databases to August 2018. A total 23 articles with 40 studies were incorporated into our analysis. RESULTS Our data show that rs486907 was not associated with the risk of prostate cancer in any populations. Nevertheless, rs627928 was reported to promote the development of prostate cancer (T vs. G: OR=1.08, 95% CI=1.01-1.15; TT+TG vs. GG: OR=1.14, 95% CI=1.03-1.25) in allele and recessive models in overall populations. Stratified analyses showed that similar results were obtained in white populations. CONCLUSIONS We report the effect of rs627928 on the development of prostate cancer and confirm that rs486907 is not involved in the risk of prostate cancer in the current meta-analysis. However, research in larger populations is needed to validate our conclusions.

RNASEL 1623A>C variant is associated with the risk of prostate cancer in African descendants

Association between ribonuclease L (RNASEL) gene 1623A>C polymorphism and prostate cancer (PCa) susceptibility has been assessed in large quantities of studies but with controversial conclusions. We undertook a pooled analysis containing 7397 PCa cases and 6088 control subjects to assess the correlation between RNASEL 1623A>C polymorphism and PCa risk. Moreover, we used enzyme-linked immunosorbent assay to test the serum RNASEL expression among patients enrolled in our centers and in-silico tools were also utilized. The overall results of our analysis indicated a positive relationship between 1623A>C variant and PCa risk (allelic contrast, odds ratio [OR] = 1.07; 95% confidence interval [CI] = 1.02-1.12; P_{heterogeneity}  = 0.575; CC vs AA, OR = 1.14; 95% CI = 1.03-1.26; P_{heterogeneity}  = 0.217; CC + CA vs AA, OR = 1.10; 95% CI = 1.01-1.19; P_{heterogeneity}  = 0.303; and CC vs CA + AA, OR = 1.08; 95% CI = 1.00-1.17; P_{heterogeneity}  = 0.298). In ethnicity subgroup analysis, similar results were especially indicated in African descendants. In addition, serum RNASEL levels in PCa cases with CC + CA genotypes were higher than those with AA genotypes. Our present study showed evidence that RNASEL 1623A>C polymorphism is related to PCa risk, especially in African descendants.

The RNASEL -1385G/A polymorphism is associated with risk of prostate cancer in Africans

The RNASEL –1385G/A (rs486907) variant has been reported to be associated with increased risk of prostate cancer. However, these associations are not consistent among studies. To address this issue, we performed a meta-analysis to evaluate the association between RNASEL –1385G/A polymorphism and prostate cancer risk. The PubMed, Embase, and Web of Science databases were searched for relevant papers published in the past 20 years from 1997 to 2017. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of associations. Based on our search for manuscripts reporting prostate cancer susceptibility related to the rs486907 polymorphism, 16 case–control studies from 13 different publications were retrieved. No significantly positive associations were found for the polymorphism and prostate cancer susceptibility in the total population. When stratified by ethnicity, the results demonstrated that the –1385G/A polymorphism was associated with a decreased cancer risk in Africans (GG vs AA: OR =0.371, 95% CI =0.176–0.783; GG/GA vs AA: OR =0.368, 95% CI =0.175–0.776). We also found that the rs486907 polymorphism was associated with a decreased cancer risk in hospital-based controls (GG vs AA: OR =0.697, 95% CI =0.488–0.996; GG + GA vs AA: OR =0.701, 95% CI =0.502–0.978). Our meta-analysis suggests that polymorphism in the RNASEL gene is a protective factor against prostate cancer in Africans. Further studies using larger sample sizes should be conducted to elucidate the role of gene polymorphism in prostate cancer risk.

Association of a common genetic variant in RNASEL and prostate cancer susceptibility

The RNASEL gene (2’, 5’-oligoisoadenylate synthetase-dependent) encodes a ribonuclease that plays a significant role in the apoptotic and antiviral activities of interferons. Various studies have used polymorphisms in the RNASEL gene to evaluate prostate cancer risk but studies that show an association between RNASEL Arg462Gln (1385G>A, R462Q, rs486907) polymorphism and prostate cancer risk are somewhat inconclusive. To assess the impact of RNASEL Arg462Gln polymorphism on prostate cancer risk, we conducted a meta-analysis of all available studies including 11,522 patients and 10,976 control subjects. The overall results indicated no positive association between the variant and prostate cancer risk. However, in a subgroup analysis by ethnicity, obvious associations were observed in Hispanic Caucasians for allelic contrast (OR = 1.18, 95% CI = 1.00 - 1.39, P_{heterogeneity} = 0.010), homozygote comparison (OR = 1.50, 95% CI = 1.02 – 2.20, P_{heterogeneity} = 0.001), and the recessive genetic model (OR = 1.44, 95% CI = 1.01 - 2.05, P_{heterogeneity} = 0.002) ; and in African descendants for homozygote comparison (OR = 2.59, 95% CI = 1.29 – 5.19, P_{heterogeneity} = 0.194) and the recessive genetic model (OR = 2.61, 95% CI = 1.30 – 5.23, P_{heterogeneity} = 0.195). In conclusion, the RNASEL Arg462Gln polymorphism may contribute to the risk of developing prostate cancer in African descendants and Hispanic Caucasians. Further larger and well-designed studies are warranted to evaluate this association in detail.

Functional and Structural Consequences of Damaging Single Nucleotide Polymorphisms in Human Prostate Cancer Predisposition Gene RNASEL

A commonly diagnosed cancer, prostate cancer (PrCa), is being regulated by the gene RNASEL previously known as PRCA1 codes for ribonuclease L which is an integral part of interferon regulated system that mediates antiviral and antiproliferative role of the interferons. Both somatic and germline mutations have been implicated to cause prostate cancer. With an array of available Single Nucleotide Polymorphism data on dbSNP this study is designed to sort out functional SNPs in RNASEL by implementing different authentic computational tools such as SIFT, PolyPhen, SNPs&GO, Fathmm, ConSurf, UTRScan, PDBsum, Tm-Align, I-Mutant, and Project HOPE for functional and structural assessment, solvent accessibility, molecular dynamics, and energy minimization study. Among 794 RNASEL SNP entries 124 SNPs were found nonsynonymous from which SIFT predicted 13 nsSNPs as nontolerable whereas PolyPhen-2 predicted 28. SNPs found on the 3' and 5' UTR were also assessed. By analyzing six tools having different perspectives an aggregate result was produced where nine nsSNPs were found to be most likely to exert deleterious effect. 3D models of mutated proteins were generated to determine the functional and structural effect of the mutations on ribonuclease L. The initial findings were reinforced by the results from I-Mutant and Project HOPE as these tools predicted significant structural and functional instability of the mutated proteins. Expasy-ProSit tool defined the mutations to be situated in the functional domains of the protein. Considering previous analysis this study revealed a conclusive result deducing the available SNP data on the database by identifying the most damaging three nsSNP rs151296858 (G59S), rs145415894 (A276V), and rs35896902 (R592H). As such studies involving polymorphisms of RNASEL were none to be found, the results of the current study would certainly be helpful in future prospects concerning prostate cancer in males.

Prostate Cancer Genetics: A Review

Over the past decades, research has focussed on identifying the genetic underpinnings of prostate cancer. It has been recognized that a number of forms of genetic changes coupled with epigenetic and gene expression changes can increase the prediction to develop prostate cancer. This review outlines the role of somatic copy number alterations (SCNAs), structural rearrangements, point mutations, and single nucleotide polymorphisms (SNPs) as well as miRNAs. Identifying relevant genetic changes offers the ability to develop novel biomarkers to allow early and accurate detection of prostate cancer as well as provide risk stratification of patients following their diagnosis. The concept of personalized or individualized medicine has gained significant attention. Therefore, a better understanding of the genetic and metabolic pathways underlying prostate cancer development offers the opportunity to explore new therapeutic interventions with the possibility of offering patient-specific targeted therapy.

Molecular pathways in prostate cancer

Objectives

Prostate cancer is a prevalent disease with a high impact on patients’ morbidity and mortality. Despite efforts to profile prostate cancer, the genetic alterations and biological processes that correlate with disease progression remain partially elusive. The purpose of this study is to review the recent evidence relating to the initiation and progression of prostate cancer in relation to the familial correlation of the disease, the genetic aberrations resulting in prostate cancer and the new molecular biology data regarding prostate cancer.

Materials and Methods

A Medline database search identified all the existing publications on the molecular events associated with the pathogenesis and evolution of prostate cancer. Particular emphasis was given on the specific genetic phenomena associated with prostate cancer.

Results

Like other cancers, prostate cancer is caused by an accumulation of genetic alterations in a cell that drives it to malignant growth. Specific genes and gene alterations have been suggested to play a role in its development and progression. Aneuploidy, loss of heterozygosity, gene mutations, hypermethylation and inactivation of specific tumour suppressor genes such as GSTpi, APC, MDR1, GPX3 and others have been detected in prostate cancers, but generally only at a low or moderate frequency. The androgen receptor (AR) signalling pathway may play a crucial role in the early development of prostate cancer, as well as in the development of androgen-independent disease that fails to respond to hormone deprivation therapies. Other alterations linked to the transition to hormone-independence include amplification of MYC and increased expression of ERBB2 and BCL2. Inflammatory changes may also contribute to the development of prostate cancer.

Conclusion

The identification of specific molecular markers for prostate cancer may lead to its earliest detection and better prediction of its behavior. The better understanding of the molecular events affecting prostate cancer progression may result in the introduction of new drugs to target these events thus providing a potential cure and a tool for prevention of this very common disease.

A single nucleotide polymorphism in inflammatory gene RNASEL predicts outcome after radiation therapy for localized prostate cancer

PURPOSE

To study associations between single nucleotide polymorphisms (SNP) in Ribonuclease L (RNASEL), a gene implicated in inflammation and prostate cancer risk, and outcomes after radiation therapy.

EXPERIMENTAL DESIGN

We followed participants in the prospective US Health Professionals Follow-Up Study treated with radiation therapy for early-stage prostate cancer. Three SNPs were genotyped based on previously determined functional and biological significance. We used multivariable Cox proportional hazards models to assess per-allele associations with the primary outcome defined as time to a composite endpoint including development of lethal prostate cancer or biochemical recurrence.

RESULTS

We followed 434 patients treated with radiation therapy for a median of 9 years. On multivariate analysis, the rs12757998 variant allele was associated with significantly decreased risk of the composite endpoint [HR: 0.65; 95% confidence interval (CI), 0.45-0.94%; P = 0.02] driven by decreased biochemical recurrence (HR: 0.60; 95% CI, 0.40-0.89%; P = 0.01) and men treated with external beam (HR: 0.58; 95% CI, 0.36-0.93%; P = 0.02). In contrast, in 516 men from the same cohort treated with radical prostatectomy, we found no significant impact of this variant on outcome. Furthermore, the rs12757998 variant allele significantly modified the association between androgen deprivation therapy and outcomes after radiation therapy (p-interaction = 0.02).

CONCLUSION

We show an association between RNASEL SNP rs12757998 and outcome after radiation therapy for prostate cancer. This SNP is associated with increased circulating C-reactive protein and interleukin-6, suggesting a potential role for inflammation in the response to radiation. If validated, genetic predictors of outcome may help inform prostate cancer management.

No association between XMRV or related gammaretroviruses in Australian prostate cancer patients

BACKGROUND

Xenotropic murine leukemia virus-related virus (XMRV) is a gammaretrovirus reported to be associated with prostate cancer (PC) and chronic fatigue syndrome (CFS). While the association of XMRV with CFS and PC has recently been discredited, no studies have been performed in Australian patients to investigate the association between PC and XMRV or related murine leukemia virus (MLV) in matched PC and normal tissue.

METHODS

Genomic DNA (gDNA) was purified from matched normal and cancer formalin-fixed paraffin-embedded (FFPE) prostate tissue from 35 Australian PC patients with Gleason scores ranging from 7 - 10. The presence of the ribonuclease L (RNase L) polymorphism R462Q was determined by allele specific PCR. Samples were screened for XMRV and related murine leukemia virus (MLV) variants by qPCR. Contaminating mouse DNA was detected using qPCR targeting mouse intracisternal A particle long terminal repeat DNA.

RESULTS

gDNA was successfully purified from 94% (66/70) of normal and cancer FFPE prostate tissues. RNase L typing revealed 8% were homozygous (QQ), 60% were heterozygous (RQ) and 32% were wild-type (RR) for the RNase L mutation. None of the 66 samples tested were positive for XMRV or related MLV sequences using broad MLV or XMRV specific primers with detection sensitivities of 1 viral copy of MLV/XMRV and XMRV DNA, respectively.

CONCLUSIONS

Using highly sensitive qPCR we found no evidence of XMRV or related gammaretroviruses in prostate tissues from 35 Australian PC patients. Our findings are consistent with other studies demonstrating that XMRV is a laboratory contaminant that has no role in the aetiology of PC.

Association of the innate immunity and inflammation pathway with advanced prostate cancer risk

Prostate cancer is the most frequent and second most lethal cancer in men in the United States. Innate immunity and inflammation may increase the risk of prostate cancer. To determine the role of innate immunity and inflammation in advanced prostate cancer, we investigated the association of 320 single nucleotide polymorphisms, located in 46 genes involved in this pathway, with disease risk using 494 cases with advanced disease and 536 controls from Cleveland, Ohio. Taken together, the whole pathway was associated with advanced prostate cancer risk (P = 0.02). Two sub-pathways (intracellular antiviral molecules and extracellular pattern recognition) and four genes in these sub-pathways (TLR1, TLR6, OAS1, and OAS2) were nominally associated with advanced prostate cancer risk and harbor several SNPs nominally associated with advanced prostate cancer risk. Our results suggest that the innate immunity and inflammation pathway may play a modest role in the etiology of advanced prostate cancer through multiple small effects.

Mitochondrial haplogroups and polymorphisms reveal no association with sporadic prostate cancer in a southern European population

BACKGROUND

It is known that mitochondria play an important role in certain cancers (prostate, renal, breast, or colorectal) and coronary disease. These organelles play an essential role in apoptosis and the production of reactive oxygen species; in addition, mtDNA also reveals the history of populations and ancient human migration. All these events and variations in the mitochondrial genome are thought to cause some cancers, including prostate cancer, and also help us to group individuals into common origin groups. The aim of the present study is to analyze the different haplogroups and variations in the sequence in the mitochondrial genome of a southern European population consisting of subjects affected (n = 239) and non-affected (n = 150) by sporadic prostate cancer.

METHODOLOGY AND PRINCIPAL FINDINGS

Using primer extension analysis and DNA sequencing, we identified the nine major European haplogroups and CR polymorphisms. The frequencies of the haplogroups did not differ between patients and control cohorts, whereas the CR polymorphism T16356C was significantly higher in patients with PC compared to the controls (p = 0.029). PSA, staging, and Gleason score were associated with none of the nine major European haplogroups. The CR polymorphisms G16129A (p = 0.007) and T16224C (p = 0.022) were significantly associated with Gleason score, whereas T16311C (p = 0.046) was linked with T-stage.

CONCLUSIONS AND SIGNIFICANCE

Our results do not suggest that mtDNA haplogroups could be involved in sporadic prostate cancer etiology and pathogenesis as previous studies performed in middle Europe population. Although some significant associations have been obtained in studying CR polymorphisms, further studies should be performed to validate these results.

[RNASEL study of genetics of prostate cancer and its relation to clinical staging]

OBJECTIVES

This study has aimed to find a possible genetic relationship between sporadic prostate cancers. An attempt is made to establish population subgroups in patients based on the genotype found and the aggressiveness of the cancer.

MATERIAL AND METHODS

A total of 231 patients with sporadic prostate cancer and 68 controls were selected. The subjects were selected by an urologist using clinical parameters such as PSA level and Gleason score. Both groups (patients and controls) were genotyped in RNASEL gene by sequencing the exons 1 and 3.

RESULTS

Statistically significant differences were found between controls and patients in some of the genotyped regions of the RNASEL gene (I97L, D541E and R462Q).

CONCLUSIONS

Thanks to the genetic profile in some regions of the genoma, such as the RNASEL gene, together with the combination of the clinical and environmental parameters, we can suggest a care and more personalized follow-up of each patient.

Nucleic Acid, Antibody, and Virus Culture Methods to Detect Xenotropic MLV-Related Virus in Human Blood Samples

The MLV-related retrovirus, XMRV, was recently identified and reported to be associated with both prostate cancer and chronic fatigue syndrome. At the National Cancer Institute-Frederick, MD (NCI-Frederick), we developed highly sensitive methods to detect XMRV nucleic acids, antibodies, and replication competent virus. Analysis of XMRV-spiked samples and/or specimens from two pigtail macaques experimentally inoculated with 22Rv1 cell-derived XMRV confirmed the ability of the assays used to detect XMRV RNA and DNA, and culture isolatable virus when present, along with XMRV reactive antibody responses. Using these assays, we did not detect evidence of XMRV in blood samples (N = 134) or prostate specimens (N = 19) from two independent cohorts of patients with prostate cancer. Previous studies detected XMRV in prostate tissues. In the present study, we primarily investigated the levels of XMRV in blood plasma samples collected from patients with prostate cancer. These results demonstrate that while XMRV-related assays developed at the NCI-Frederick can readily measure XMRV nucleic acids, antibodies, and replication competent virus, no evidence of XMRV was found in the blood of patients with prostate cancer.

Genetic variation in RNASEL and risk for prostate cancer in a population-based case-control study

BACKGROUND

Linkage studies have implicated chromosome 1q24 as a putative locus for hereditary prostate cancer. The RNASEL gene maps to 1q24 and has been associated with prostate cancer risk in multiple family-based linkage studies. The RNASEL gene product combats viral infection by degrading viral RNA and inducing apoptosis of infected cells. Few studies have evaluated the role of RNASEL variants in unselected or sporadic prostate cancer, or have considered the potential interaction between RNASEL variants and patient characteristics associated with past infection.

METHODS

Ten SNPs in the RNASEL gene were genotyped in 1,308 prostate cancer cases and 1,267 age-matched controls from prior population-based, case-control studies. The association between each SNP and haplotype with prostate cancer risk was calculated using logistic regression. Associations stratified by Gleason score were evaluated using polytomous regression. The likelihood ratio test was used to investigate effect modification.

RESULTS

Two RNASEL SNPs were associated with overall increases in prostate cancer risk (OR = 1.13 for each variant allele of rs12723593; OR = 1.88 for any variant allele of rs56250729). Risk estimates did not vary substantially by Gleason score, but there was effect modification for the variant allele of rs635261 by history of prostatitis (P = 0.02).

CONCLUSIONS

This study identified three RNASEL variants that are associated with risk for prostate cancer. Further research is required to confirm these results and to better understand the potential role RNASEL variants may play in the etiology of sporadic prostate cancer.

RNASEL Asp541Glu and Arg462Gln polymorphisms in prostate cancer risk: evidences from a meta-analysis

Epidemiological studies have evaluated the association between RNASEL Asp541Glu and Arg462Gln polymorphisms and prostate cancer (PCa) risk. However, the results remain inconclusive. To derive a more precise estimation of the association between RNASEL polymorphisms and PCa risk, we performed a meta-analysis based on nineteen case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. Overall, we found that both Asp541Glu and Arg462Gln polymorphisms were not associated with PCa risk (for Asp541Glu polymorphism: Glu/Glu vs. Asp/Asp: OR 1.17, 95% CI: 0.95-1.45, P = 0.13; Glu/Asp vs. Asp/Asp: OR 1.02, 95% CI: 0.92-1.14, P = 0.70; for Arg462Gln polymorphism: Gln/Gln vs. Arg/Arg: OR 0.98, 95% CI: 0.88-1.08, P = 0.62; Gln/Arg vs. Arg/Arg: OR 0.97, 95% CI: 0.91-1.04, P = 0.53). The insignificant association was maintained in the dominant and the recessive genetic models. In subgroup analyses, the significant association was not detected in Caucasian populations. However, we found the significant association of RNASEL Asp541Glu polymorphism with sporadic PCa (Glu/Glu vs. Asp/Asp: OR 1.29, 95% CI: 1.04-1.59, P = 0.02; Glu/Asp vs. Asp/Asp: OR 1.24, 95% CI: 1.03-1.50, P = 0.03). In conclusion, we found that these RNASEL polymorphisms were not related to overall PCa risk, especially in Caucasians. However, in subgroup analyses we found a suggestion that RNASEL 541Gln allele might be a low-penetrent risk factor for sporadic PCa.

2'-5' oligoadenylate synthetase 1 polymorphism is associated with prostate cancer

BACKGROUND

The antiviral, proapoptotic, antiproliferative gene 2'-5' oligoadenylate synthetase (2-5OAS1) converts adenosine triphosphate into a series of 2'-5' oligoadenylates (2-5A). In turn, 2-5A activates latent ribonuclease (RNaseL), a candidate hereditary prostate cancer gene. OAS1 polymorphism (reference single nucleotide polymorphism [SNP] 2660 [rs2660]) has been associated with increased susceptibility to infections and various diseases. In general, the low-enzyme-activity adenine-adenine (AA) genotype promotes susceptibility, whereas the high-enzyme-activity guanosine-guanosine (GG) genotype confers protection. In this study, the authors investigated the association of this functional OAS1 polymorphism (rs2660) with prostate cancer.

METHODS

Sample size and power were calculated using a power calculation software program for case-control genetic association analyses. Genomic DNA samples from a control group (n = 140) and from a case group of patients with prostate cancer (n = 164) were used for genotyping SNPs rs2660, rs1131454, and rs34137742 in all samples. Statistical analyses were performed using a logistic regression model.

RESULTS

A significant association was observed between the rs2660 genotype (A/G) and prostate cancer. Genotype AA increased the risk, whereas genotype GG decreased the risk of prostate cancer. The GG genotype was not observed in the African American samples. The AA genotype also increased the risk of prostate cancer with age.

CONCLUSIONS

The OAS1 SNP rs2660 AA genotype was associated significantly with prostate cancer, whereas the GG genotype protected against prostate cancer. OAS1 rs2660 may be a prostate cancer susceptibility polymorphism, which is a significant observation, especially in a context of the OAS1-RNaseL pathway. Thus, a functional defect in OAS1 because of the rs2660 SNP not only can attenuate RNaseL function but also can alter cell growth and apoptosis independent of RNaseL.

An update analysis of two polymorphisms in encoding ribonuclease L gene and prostate cancer risk: involving 13,372 cases and 11,953 controls

Encoding ribonuclease L (RNASEL) is a ubiquitously expressed latent endoribonuclease involved in the mediation of antiviral and pro-apoptotic activities of the interferon-inducible 2-5A system. Although the relationship between RNASEL gene polymorphisms and prostate cancer (PCa) risk has been widely reported, results were somewhat controversial and underpowered. Now, we performed an update analysis of 14 publications evaluating the association between RNASEL R462Q and D541E polymorphisms and PCa risk. We conducted a literature search of PubMed database to identify all eligible articles that examined the association of RNASEL R462Q and D541E polymorphisms with PCa. Odds ratios (OR) with 95% confidence intervals (CI) were estimated to assess these association. R462Q showed a significantly elevated effect on Africans (QQ vs. RR: OR = 2.50, 95% CI = 1.28-4.87, P (heterogeneity) = 0.231). In addition, PCa men who contain 462Q genotype had a higher Gleason score ≥ 7 (OR = 1.16, 95% CI = 1.05-1.28, P (heterogeneity) = 0.906). On the other hand, D541E was associated with increased total PCa. In the stratified analysis by race, there was also significantly increased PCa in Africans and Caucasians, as well as in sporadic PCa studies (OR = 1.09, 95% CI = 1.04-1.15, P (heterogeneity) = 0.078). Our update analysis showed evidence that RNASEL R462Q and D541E polymorphisms were associated with PCa risk. Still more well-designed studies should be performed to clarify the role of these two polymorphisms in the development of PCa.

RNASEL -1385G/A polymorphism and cancer risk: a meta-analysis based on 21 case-control studies

Polymorphisms in the endoribonuclease L (RNASEL) gene have been hypothesized to increase the incidence of cancer. The common sequence variation in RNASEL, -1385G/A (rs486907) has been involved in several types of cancer risk. However, results of the related published studies remained conflicting rather than conclusive. To clarify the role of RNASEL -1385G/A genotype in global cancer, we performed a meta-analysis of all the available published studies involving 8,732 cancer patients and 8,748 control subjects. The overall results indicated that there was no major influence of the variant on cancer risk. However, stratified analysis by ethnicity showed that the RNASEL -1385G/A polymorphism has an increased cancer risk in African descendents in the homozygote comparison (OR = 2.59, 95% CI = 1.27-5.27), although no association was found in the analysis stratified by cancer type (OR = 1.12, 95% CI = 0.94-1.35). This meta-analysis suggested that the RNASEL -1385G/A polymorphism is associated with cancer risk in African descendents. To draw more comprehensive conclusions, further prospective studies with larger numbers of participants worldwide are still required to examine associations between RNASEL -1385G/A polymorphism and cancer risk.

Evidence and controversies on the role of XMRV in prostate cancer and chronic fatigue syndrome

The recent discovery of xenotropic murine leukaemia virus-related virus (XMRV) in prostate cancer tissues and in the blood of individuals suffering from chronic fatigue syndrome has attracted considerable interest. However, the relevance and significance of XMRV to human disease remain unclear, since the association has not been confirmed in other studies. XMRV is the first gammaretrovirus to be found in humans. XMRV and murine leukaemia viruses share similar structures and genomic organisation. Human restriction factors such as APOBEC3 or tetherin inhibit XMRV replication. Although XMRV induces low rates of transformation in cell culture, it might be able to induce cancer by low-frequency insertional activation of oncogenes or through the generation of highly active transforming viruses. A preference for regulatory regions of transcriptional active genes has been observed after a genomic-wide analysis of XMRV integration sites. Genes related to carcinogenesis and androgen signalling have been identified in the vicinity of integration sites. The XMRV genome contains a glucocorticoid responsive element, and androgens could modulate viral replication in the prostate. Evidence supporting the involvement of XMRV in chronic fatigue syndrome is still very weak, and needs further confirmation and validation. Currently approved anti-retroviral drugs such as zidovudine, tenofovir and raltegravir are efficient inhibitors of XMRV replication in vitro. These drugs might be useful to treat XMRV infection in humans. The identification of XMRV has potentially serious health implications for the implementation of novel techniques including gene therapy or xenotransplantation, while raising concerns on the need for screening donated blood to prevent transmission through transfusion.

Contribution of HPC1 (RNASEL) and HPCX variants to prostate cancer in a founder population

BACKGROUND

Prostate cancer is a genetically complex disease with locus and disease heterogeneity. The RNASEL gene and HPCX locus have been implicated in hereditary prostate cancer; however, their contributions to sporadic forms of this malignancy remain uncertain.

METHODS

Associations of prostate cancer with two variants in the RNASEL gene (a founder mutation, 471delAAAG, and a non-synonymous SNP, rs486907), and with five microsatellite markers in the HPCX locus, were examined in 979 cases and 1,251 controls of Ashkenazi Jewish descent. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression models.

RESULTS

There was an inverse association between RNASEL rs486907 and prostate cancer in younger men (<65 years) and those with a first-degree relative with prostate cancer; men with AA genotype had ORs of 0.64 and 0.47 (both P < 0.05), respectively, in comparison to men with GG genotype. Within the HPCX region, there were positive associations for allele 135 of bG82i1.1 marker (OR = 1.77, P = 0.01) and allele 188 of DXS1205 (OR = 1.65, P = 0.02). In addition, allele 248 of marker D33 was inversely associated (OR = 0.65, P = 0.05) with Gleason score ≥7 tumors.

CONCLUSIONS

Results suggest that variants in RNASEL contribute to susceptibility to early onset and familial forms of prostate cancer, whereas HPCX variants are associated with prostate cancer risk and tumor aggressiveness. The observation that a mutation predicted to completely inactivate RNASEL protein was not associated with prostate cancer, but that a missense variant was associated, suggests that the effect is due to either partial inactivation of the protein, and/or acquisition of a new protein activity.

Arg462Gln and Asp541Glu polymorphisms in ribonuclease L and prostate cancer risk: a meta-analysis

Objective

The association between ribonuclease L (RNASEL) gene polymorphisms and prostate cancer risk has been widely reported, but the results of these studies remained controversial and underpowered. We performed a meta-analysis of 28 studies to evaluate the association between Arg462Gln and Asp541Glu polymorphisms in the RNASEL gene and prostate cancer risk.

Methods

Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between RNASEL polymorphisms and prostate cancer risk.

Results

A significantly increased prostate cancer risk was found for the Arg462Gln polymorphism in Africans (Gln/Gln vs Arg/Arg: OR = 2.50, 95%CI = 1.28-4.87; Gln/Gln vs Gln/Arg + Arg/Arg: OR = 2.54, 95%CI = 1.30-4.95), but not in Europeans and Asians. Additionally, the Asp541Glu polymorphism was associated with increased total prostate cancer risk (Glu-allele vs Asp-allele: OR = 1.04, 95%CI = 1.01-1.07; Glu/Glu vs Asp/Asp: OR = 1.22, 95%CI = 1.03-1.46; Glu/Glu vs Glu/Asp + Asp/Asp: OR = 1.09, 95%CI = 1.02-1.16). In the stratified analysis for the Asp541Glu polymorphism, there was a significantly increased prostate cancer risk in Africans and Europeans, and in hospital-based prostate cancer cases.

Conclusion

The meta-analysis results showed evidence that RNASEL Arg462Gln and Asp541Glu polymorphisms are associated with prostate cancer risk and could be low-penetrance prostate cancer susceptibility biomarkers.

Association of HPC2/ELAC2 and RNASEL non-synonymous variants with prostate cancer risk in African American familial and sporadic cases

INTRODUCTION

The RNASEL and HPC2/ELAC2 genes have been implicated in hereditary prostate cancer. Further assessment of the role of these genes in sporadic prostate cancer in African American men (AAM) is warranted.

METHODS

Genotyping of HPC2/ELAC2 variants (S217L, A541T), along with RNASEL variants (R462Q and E541D) was completed in 155 African American sporadic and 88 familial prostate cancer cases, and 296 healthy male controls. Logistic regression analysis was performed and odds ratios (OR) were calculated, while correcting for both age and population stratification using admixture informative markers.

RESULTS

The HPC2/ELAC2 217L allele was significantly associated with risk of prostate cancer when taking all cases into account (OR = 1.6; 1.0-2.6; P = 0.03). The RNASEL 541D allele was associated with a decrease in risk of prostate cancer in sporadic cases (OR = 0.4; 0.2-0.8; P = 0.01). We did not detect an association between prostate cancer risk and the RNASEL R462Q variant. Results from haplotype analyses of the two RNASEL variants revealed highly significant differences in haplotype allele frequencies between cases and controls suggesting a synergistic effect at the RNASEL locus. One haplotype in particular (462R-541D) is far more frequent in our control population and shows a strong protective effect against prostate cancer (OR = 0.47, P = 8.1 x 10(-9)).

CONCLUSIONS

These results suggest that HPC2/ELAC2 and RNASEL may play a role, however minor, in prostate cancer risk among AAM.

Prevalence of human gammaretrovirus XMRV in sporadic prostate cancer

BACKGROUND

We previously identified a novel exogenous gammaretrovirus (xenotropic murine leukemia virus-related gammaretrovirus (XMRV)) using a pan-viral microarray. XMRV is the first MLV-related virus found in human infection. Forty percent (8/20) of familial prostate cancer patients homozygous for a mutation in RNase L (R462Q) were positive for XMRV, while the virus was rarely (1/66) detected in familial prostate cancer patients heterozygous for R462Q or carrying the wild type allele.

OBJECTIVES

To determine the presence of XMRV in non-familial prostate cancer samples.

STUDY DESIGN

RNA from prostate tissue was analyzed for XMRV using nested RT-PCR. In all samples, RNase L (R462Q) genotyping was performed using an allele-specific PCR.

RESULTS

XMRV-specific sequences were detected in one of 105 tissue samples from non-familial prostate cancer patients and from one of 70 tissue samples from men without prostate cancer. The two XMRV-positive patients were wild type or heterozygous for the R462Q mutation and thus carried at least one fully functional RNase L allele.

CONCLUSIONS

XMRV was rarely detected in non-familial prostate cancer samples from Northern European patients. The homozygous mutation R462Q (QQ) was significantly underrepresented (<6%) in this cohort when compared to other studies (11-17%).

Germline mutation in RNASEL predicts increased risk of head and neck, uterine cervix and breast cancer

The Background

Ribonuclease L (RNASEL), encoding the 2′-5′-oligoadenylate (2-5A)-dependent RNase L, is a key enzyme in the interferon induced antiviral and anti-proliferate pathway. Mutations in RNASEL segregate with the disease in prostate cancer families and specific genotypes are associated with an increased risk of prostate cancer.

Infection by human papillomavirus (HPV) is the major risk factor for uterine cervix cancer and for a subset of head and neck squamous cell carcinomas (HNSCC). HPV, Epstein Barr virus (EBV) and sequences from mouse mammary tumor virus (MMTV) have been detected in breast tumors, and the presence of integrated SV40 T/t antigen in breast carcinomas correlates with an aggressive phenotype and poor prognosis.

A genetic predisposition could explain why some viral infections persist and induce cancer, while others disappear spontaneously. This points at RNASEL as a strong susceptibility gene.

Methodology/Principal Findings

To evaluate the implication of an abnormal activity of RNase L in the onset and development of viral induced cancers, the study was initiated by searching for germline mutations in patients diagnosed with uterine cervix cancer. The rationale behind is that close to 100% of the cervix cancer patients have a persistent HPV infection, and if a defective RNase L were responsible for the lack of ability to clear the HPV infection, we would expect to find a wide spectrum of mutations in these patients, leading to a decreased RNase L activity. The HPV genotype was established in tumor DNA from 42 patients diagnosed with carcinoma of the uterine cervix and somatic tissue from these patients was analyzed for mutations by direct sequencing of all coding and regulatory regions of RNASEL. Fifteen mutations, including still uncharacterized, were identified. The genotype frequencies of selected single nucleotide polymorphisms (SNPs) established in the cervix cancer patients were compared between 382 patients with head and neck squamous cell carcinomas (HNSCC), 199 patients with primary unilateral breast cancer and 502 healthy Danish control individuals. We found that the genotype frequencies of only one of the 15 mutations, the yet uncharacterized 5′UTR mutation rs3738579 differed significantly between cancer patients and control individuals (P-value: 4.43×10⁻⁵).

Conclusion/Significance

In conclusion, we have discovered an increased risk, a heterozygous advantage and thereby a protective effect linked to the RNASEL SNP rs3738579. This effect is found for patients diagnosed with carcinoma of the uterine cervix, HNSCC, and breast cancer thus pointing at RNASEL as a general marker for cancer risk and not restricted to familial prostate cancer.

Polymorphisms in DNA repair genes, smoking, and pancreatic adenocarcinoma risk

Base excision repair and nucleotide excision repair are vital responses to multiple types of DNA damage, including damage from tobacco exposure. Single-nucleotide polymorphisms (SNP) in these pathways may affect DNA repair capacity and therefore influence risk for cancer development. We performed a clinic-based, case-control study comprising 481 consecutive patients with confirmed pancreatic adenocarcinoma and 625 healthy controls. Allele and genotype frequencies for 16 SNPs in DNA repair genes ERCC1, XPD/ERCC2, XPC, XPF/ERCC4, OGG1, and XRCC1 were compared after adjusting for age, sex, and smoking history. Subgroup analysis by sex and smoking history was performed. Carriers of one or two XPF/ERCC4 minor alleles at R415Q had decreased risk of pancreatic adenocarcinoma compared with those who had two major alleles [odds ratio (OR), 0.59; 95% confidence interval (95% CI), 0.40-0.85]. Heavy smokers (>40 pack-years) had increased risk for cancer if they were carriers of at least one minor allele for XPD/ERCC2 at D312N (OR, 2.78; 95% CI, 1.28-6.04) or D711D (OR, 2.19; 95% CI, 1.01-4.73). No other significant differences in risk were identified. Minor alleles in DNA repair genes XPF/ERCC4 and XPD/ERCC2 were associated with altered risk for pancreatic cancer.

Analysis of the RNASEL/HPC1, and macrophage scavenger receptor 1 in Asian-Indian advanced prostate cancer

OBJECTIVES

Prostate cancer (PC) varies widely by geographic location and ethnicity. American men have a high PC risk but most have localized disease. In contrast, Asian Indians have a low PC risk but most are diagnosed with metastatic disease. Epidemiological and genetic data suggest an important role of genetic susceptibility in PC. Most studies were performed in whites. Substantially less is known about gene variation-associated PC in low-risk populations. The objective of this study was to investigate the role of RNASEL and MSR1 in Asian-Indian men with advanced PC.

METHODS

We genotyped DNA samples obtained from 113 cases and 245 age-matched controls (Northern India).

RESULTS

For RNASEL, we identified 8 variants (7 novel and 1 previously published, D541E), including 4 exonic, 3 intronic, and 1 change in the 3'-noncoding region. Of these, we detected a novel 4-bp truncation mutation (Val51ArgfsX2) in 2 controls. For MSR1, we identified 4 novel variants (2 intronic and 2 exonic) and 2 previously reported variants (P275A and promoter -4,637 A>G). We also genotyped 3 common MSR1 variations (promoter -14,742 A>G, IVS5-59 C>A, and IVS7 delinsTTA). We found no associations among any of the sequence variations and PC. Three major haplotypes account for most of all MSR1 haplotypes in Asian Indians. Haplotype frequencies were not significantly different between cases and controls.

CONCLUSIONS

Our results do not support a role for RNASEL, or MSR1 mutations in advanced Asian-Indian PC. This study warrants additional investigations of these genes in etiology particularly among individuals from diverse ethnic and geographic groups.

RNASEL and RNASEL-inhibitor variation and prostate cancer risk in Afro-Caribbeans

BACKGROUND

Afro-Caribbeans from Tobago are at high risk of developing prostate cancer. This elevated risk of prostate cancer is shared by populations of African ancestry living in diverse environments in the Western hemisphere. Variation in the ribonuclease L (RNASEL) gene has recently been reported to be associated with an increased risk of prostate cancer. However, whether RNASEL variation contributes to the increased risk of prostate cancer observed in populations of African ancestry remains unclear.

METHODS

We resequenced the positional candidate gene RNASEL in 48 prostate cancer cases and genotyped the previously reported R462Q and D541E polymorphisms in 230 prostate cancer cases and 458 controls. We also examined the inhibitor of RNASEL (ABCE1) for variation associated with prostate cancer risk.

RESULTS

We found no evidence of association between R462Q and D541E polymorphisms and prostate cancer risk in our case/control analysis. A novel variant (K294E) was identified in a single heterozygous individual with prostate cancer. We also observed a 20 bp insertion/deletion polymorphism 1,109 bp upstream of the initiation codon, but this variant was not associated with prostate cancer. We identified 16 single nucleotide polymorphisms in the ABCE1 gene, only 3 of which had a minor allele frequency >5%. A common A/G transition -1,071 bp from the transcriptional start site was genotyped and showed no evidence of association with prostate cancer.

CONCLUSIONS

Our results suggest that common variation in the putative prostate cancer susceptibility gene, RNASEL, or its inhibitor does not contribute significantly to prostate cancer risk in this Afro-Caribbean population.

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

PURPOSE

The RNASEL gene at 1q25 has been identified as a hereditary prostate cancer susceptibility gene, but to date, no study has investigated the role of RNASEL variants in Hispanic Caucasian men with prostate cancer.

EXPERIMENTAL DESIGN

Two RNASEL common variants, located at amino acids 462 and 541, were genotyped in non-Hispanic Caucasian, Hispanic Caucasian, and African American prostate cancer cases and controls.

RESULTS

The RNASEL 462 AA genotype was found to increase prostate cancer risk over 4-fold in Hispanic Caucasians [odds ratio (OR), 4.43; 95% confidence interval (95% CI), 1.68-11.68; P = 0.003] and over 10-fold in African Americans (OR, 10.41; 95% CI, 2.62-41.40; P = 0.001) when compared with the GG genotype. Analysis of the RNASEL 541 variant showed that Hispanic Caucasian patients with the GG genotype had a statistically significant increase in their risk for developing prostate cancer when compared with the TT and GT genotypes (OR, 1.91; 95% CI, 1.16-3.14; P = 0.01). A common G-T haplotype for the combination of the RNASEL 462 and 541 variants was found to occur more frequently in controls compared with cases in African Americans (P = 0.04) but not in non-Hispanic Caucasians or Hispanic Caucasians.

CONCLUSIONS

This is the first study that investigates the association of prostate cancer risk with RNASEL variants in Hispanic men. Our data support the role of RNASEL as a predisposition gene for prostate cancer and showed a significant association between the RNASEL 462 variant and prostate cancer risk in African Americans and Hispanic Caucasians.

DNA variation in MSR1, RNASEL and E-cadherin genes and prostate cancer in Poland

INTRODUCTION

We investigated whether or not inherited variation in MSR1, RNASEL and E-cadherin contribute to prostate cancer risk in Poland.

MATERIAL AND METHODS

We sequenced the coding region of these three genes in individuals from Poland and identified five common DNA variants (R462Q and D541E in RNASEL, R293X and P275A in MSR1, and 2076C>T (A692A) in E-cadherin). These five variants and the -160C>A promoter change in E-cadherin were genotyped in 737 prostate cancer cases and 511 controls.

RESULTS

The frequencies of genotyped variants in MSR1, RNASEL and E-cadherin genes in cases and controls were similar. We did not see any association for the studied variants when cases were stratified by age of diagnosis, by family history, by prostate-specific antigen level at the time of diagnosis, by Gleason sore or by tumor stage.

CONCLUSIONS

Inherited variation in RNASEL, MSR1 and E-cadherin genes do not seem to contribute to prostate cancer development in Poland.

Genetic variability in inflammation pathways and prostate cancer risk

Genetic susceptibility to prostate cancer has been consistently observed by a large number of studies. Recently, several pieces of evidence obtained from epidemiological and pathological studies support that chronic inflammation in prostate tissues may play a role in prostate cancer development. Multiple genes that play critical roles in inflammatory pathways have been associated with prostate cancer risk. In this article we review the key genetic findings of the associated genes. This includes 2 genes identified through family studies, ribonuclease L (RNASEL) and macrophage scavenger receptor 1 (MSR1), as well as a number of genes suggested by case-control studies, such as macrophage inhibitory cytokine-1 (MIC-1), interleukins (IL-8, IL-10), vascular endothelial growth factor (VEGF), intercellular adhesion molecule (ICAM), and Toll-like receptors (TLR-4, TLR-1-6-10 gene cluster). Overall, recent studies seem to suggest multiple genes work together to increase prostate risk, and this is consistent with the reality that inflammation is a very complex process. Thus, future studies are expected to place an emphasis on the study of gene-gene interactions. Advances in high throughput genotyping, data mining, and algorithm development are needed in order to produce interpretable results.

RNASEL Arg462Gln polymorphism and prostate cancer in PLCO

BACKGROUND

The Gln allele of the Arg462Gln polymorphism in RNASEL results in a threefold decrease in enzymatic activity, a reported deficiency in apoptotic response, and has been associated with prostate cancer in some high-risk family studies. The relationship of this variant to sporadic prostate cancer remains uncertain.

METHODS

We conducted a nested case-control study of 1,317 prostate cancer cases and 1,842 controls from the screening arm of the prostate, lung, colorectal, and ovarian (PLCO) cancer screening trial. Conditional logistic regression was used to evaluate the association between the RNASEL Arg462Gln polymorphism and prostate cancer.

RESULTS

No statistically significant association was observed between the Arg462Gln polymorphism and prostate cancer (compared to Arg/Arg, Gln/Arg: OR= 0.99 95% CI 0.84-1.16; Gln/Gln: OR= 0.95 95% CI 0.74-1.21), although slight non-significant differences in risk were observed among men with the Gln/Gln genotype by stage and grade.

CONCLUSIONS

These results suggest that the RNASEL Gln/Gln genotype does not play an important role in the etiology of prostate cancer in the general population.

Two common chromosome 8q24 variants are associated with increased risk for prostate cancer

Two variants (rs1447295/DG8S737) of chromosome 8q24 were recently reported to be associated with increased risk of prostate cancer (PC). To confirm this finding, we genotyped and compared the frequencies of these polymorphisms among 1,121 Caucasian men with PC (435 men with familial PC, 491 men with sporadic PC, and 195 men with aggressive PC) to 545 population-based controls. For the single nucleotide polymorphism marker rs1447295, frequencies of the minor allele (A) were 10.3% in controls, 11.9% in sporadic cases, 16.7% in familial cases, and 17.2% in aggressive cases. Compared with controls, the A allele was significantly more common in both familial PC [odds ratios (OR), 1.93; 95% confidence intervals (95% CI), 1.37-2.72; P = 0.0004] and aggressive PC (OR, 1.87; 95% CI, 1.28-2.74; P = 0.0005) but not for sporadic PC (OR, 1.16; 95% CI, 0.85-1.58; P = 0.25). Although the A allele was more frequent in aggressive PC cases when compared with controls, the allele frequencies were similar among cases with high- and low-grade PC (Gleason grades <7 and >/=7, respectively). For the microsatellite marker DG8S737, the -8 allele was significantly more frequent in familial PC (OR, 1.68; 95% CI, 1.09-2.60; P = 0.031), whereas the -10 allele was more frequent in aggressive PC (OR, 2.85; 95% CI, 1.52-5.36; P = 0.0004). Haplotype analysis showed significant differences in haplotype frequencies between the familial PC (P = 0.006) and aggressive PC (P = 0.005) cases versus controls. The -8/A haplotype showed the strongest association with familial PC (P = 0.008), whereas the -10/A haplotype was most strongly associated with aggressive PC (P = 0.00005). These results further confirm the importance of these two polymorphic variants (rs1447295 and DG8S737) as risk factors for PC. However, the mechanism explaining this increased risk has not yet been established.

Truncating variants in p53AIP1 disrupting DNA damage-induced apoptosis are associated with prostate cancer risk

Germ line mutations in several genes (BRCA1, BRCA2, and CHEK2) whose products are involved in the DNA damage-signaling pathway have been implicated in prostate cancer risk. To identify additional genes in this pathway that might confer susceptibility to this cancer, we analyzed a recently identified DNA damage-response gene, p53AIP1 (a gene encoding for p53-regulated apoptosis-inducing protein 1), for genetic variants in prostate cancer. Five novel germ line variants were identified. The two truncating variants (Ser(32)Stop and Arg(21)insG) were found in 3% (4 of 132) of unselected prostate tumor samples. Genotyping of the two variants in an additional 393 men with sporadic prostate cancer showed a frequency of 3.1% (12 of 393) in contrast to 0.6% (2 of 327) in 327 unaffected men (Fisher's exact test, P = 0.018), with an odds ratio (OR) of 5.1 [95% confidence interval (95% CI), 1.1-23.0]. In addition, two of six tumors carrying the truncating variants were associated with loss of heterozygosity of the wild-type alleles, suggesting that p53AIP1 may act as a tumor suppressor. We also showed that the truncated p53AIP1 was unable to induce apoptosis and suppress cell growth in HeLa and COS-7 cells. These results suggest that loss-of-function variants in p53AIP1 associated with the risk of sporadic prostate cancer and further support the concept that the genetic defects in the DNA damage-response genes play an important role in the development of prostate cancer.

Systematic replication study of reported genetic associations in prostate cancer: Strong support for genetic variation in the androgen pathway

BACKGROUND

Association studies have become a common and popular method to identify genetic variants predisposing to complex diseases. Despite considerable efforts and initial promising findings, the field of prostate cancer genetics is characterized by inconclusive reports and no prostate cancer gene has yet been established.

METHODS

We performed a literature review and identified 79 different polymorphisms reported to influence prostate cancer risk. Of these, 46 were selected and tested for association in a large Swedish population-based case-control prostate cancer population.

RESULTS

We observed significant (P < 0.05) confirmation for six polymorphisms located in five different genes. Three of them coded for key enzymes in the androgen biosynthesis and response pathway; the CAG repeat in the androgen receptor (AR) gene (P = 0.03), one SNP in the CYP17 gene (P = 0.04), two SNPs in the SRD5A2 gene (P = 0.02 and 0.02, respectively), a deletion of the GSTT1 gene (P = 0.006), and one SNP in the MSR1 gene, IVS5-59C > A, (P = 0.009).

CONCLUSIONS

Notwithstanding the difficulties to replicate findings in genetic association studies, our results strongly support the importance of androgen pathway genes in prostate cancer etiology.

RNASEL gene polymorphisms and the risk of prostate cancer: a meta-analysis

PURPOSE

Studies revealing conflicting results on the role of RNASEL polymorphisms Glu265X, Arg462Gln, and Asp541Glu on prostate cancer risk led us to perform a meta-analysis to investigate the association of these polymorphisms and prostate cancer risk.

EXPERIMENTAL DESIGN

Relevant studies were selected by searching PubMed from January 1996 to August 2005 using keywords "RNASEL gene AND prostate cancer." For each study, odds ratio (OR) with 95% confidence interval (95% CI) was calculated to estimate the gene effect. Pooled estimates of the OR were computed using the random effects model.

RESULTS

Ten studies were included in the meta-analysis. The overall results suggested no major influence of these variants on prostate cancer risk. However, analysis of the Asp541Glu polymorphism by ethnic populations showed that Asp/Glu (familial cases versus control: OR, 1.38; 95% CI, 1.04-1.82; sporadic cases versus control: OR, 1.26; 95% CI, 1.07-1.48; prostate cancer versus control: OR, 1.29; 95% CI, 1.12-1.48) and Asp/Glu + Glu/Glu (familial cases versus control: OR, 1.37; 95% CI, 1.10-1.70; sporadic cases versus control: OR, 1.24; 95% CI, 1.07-1.44; prostate cancer versus control: OR, 1.27; 95% CI, 1.13-1.44) increased prostate cancer risk in Caucasians, thus suggesting a dominant model for the Glu variant.

CONCLUSIONS

Compared with the genotype Asp/Asp, the Glu variant at the Asp541Glu polymorphism increases prostate cancer risk by <2-fold in Caucasians, regardless of family history of the disease. This suggests that genuine genetic effects of this polymorphism may account for only a part of prostate cancer in the Caucasian population.

Tumour suppressor function of RNase L in a mouse model

RNase L is one of the key enzymes involved in the molecular mechanisms of interferon (IFN) actions. Upon binding with its activator, 5'-phosphorylated, 2'-5' oligoadenylates (2-5A), RNase L plays an important role in the antiviral and anti-proliferative functions of IFN, and exerts proapoptotic activity independent of IFN. In this study, we have found that RNase L retards proliferation in an IFN-dependent and independent fashion. To directly measure the effect of RNase L on tumour growth in the absence of other IFN-induced proteins, human RNase L cDNA was stably expressed in P-57 cells, an aggressive mouse fibrosarcoma cell line. Three clonal cell lines were isolated in which the overexpression of RNase L was 15-20-fold of the endogenous level. Groups of five nude mice were injected subcutaneously with either the human RNase L overexpressing clones (P-RL) or control cells transfected with an empty vector (P-Vec). Tumour growth by the two cell lines was monitored by measuring tumour volumes. In the P-RL group, tumour formation was significantly delayed and the tumours grew much slower compared to the control group. Morphologically, the P-RL tumour appeared to have more polygonal cells and increased single cell tumour necrosis. Interestingly, P-RL tumours eventually started to grow. Further analysis revealed, however, that these tumours no longer expressed ectopic RNase L. Our findings suggest that RNase L plays a critical role in the inhibition of fibrosarcoma growth in nude mice.

The 471delAAAG mutation and C353T polymorphism in the RNASEL gene in sporadic and inherited cancer in Israel

The rate of RNASEL 471delAAAG mutation was previously reported to be less than 7% in Ashkenazi prostate cancer patients. It seems plausible that the same mutation may also be involved in breast/ovarian cancer predisposition in Jewish individuals. To evaluate the role of this mutation in cancer predisposition, a total of 1011 individuals including 294 Jewish men with prostate cancer, 61 Ashkenazi women with ovarian cancer and 50 unaffected women, matched for age and ethnicity, were genotyped for sequence anomalies in a single RNASEL gene amplicon using DGGE and sequencing. Additionally, 209 Ashkenazi BRCA1/2 mutation carriers, 205 high-risk non-carriers matched for cancer type and age at diagnosis, and 192 healthy Ashkenazi women were screened, using DHPLC and restriction methods. The 471delAAAG mutation was detected in a single male with prostate cancer (1/294, 0.3%), in two ovarian cancer patients (2/141, 1.4%) and in one of 242 healthy controls (0.41%). An abnormal DHPLC profile identical to the one produced by the 471delAAAG mutation was noted in 23 additional women. The rate of this polymorphism was significantly elevated in high-risk non-carrier women (16/205; 7.8%) than in BRCA1/2 carriers (2/209; 1.0%) and controls (5/192; 2.6%) (chi = 11.670; P < 0.001). Sequence analysis disclosed a silent polymorphism in Valine at codon 118: c.353 C- > T.The 471delAAAG mutation occurs rarely in Israeli prostate and breast/ovarian cancer patients. A silent polymorphism in the RNASEL gene occurs more prevalently in high-risk Ashkenazi breast/ovarian cancer patients without a BRCA1/2 mutation.

Role of the Nijmegen Breakage Syndrome 1 Gene in Familial and Sporadic Prostate Cancer

The Nijmegen breakage syndrome 1 (NBS1) gene, which participates in DNA double strand break repair, has been postulated to be a susceptibility factor for a number of cancers, including prostate cancer. Numerous mutations have been identified in NBS1, including the founder mutation 657del5. In this study, a number of analyses were done to determine whether mutations in NBS1 are associated with an increased risk for prostate cancer. The frequency of the 657del5 mutation in both familial prostate cancer cases (1,819 affected men among 909 families) and sporadic prostate cancer cases (1,218 affected men) collected from five centers participating in the International Consortium for Prostate Cancer Genetics were compared with that found in 697 normal controls. Seven individuals were identified to carry the mutation among the 3,037 cases screened: four in the familial group (three from one family and one from another) and three in the sporadic cases. The carrier frequency was 0.22% (2 of 909) for the probands and 0.25% (3 of 1,218) for the sporadic cases of prostate cancer. The 657del5 mutation was not detected in either the 293 unaffected members of the prostate cancer families or in the 697 control samples tested. The entire NBS1 gene was also sequenced in 20 of the youngest affected individuals from the Finnish group of familial cases to identify the presence of possible mutations in this high-risk group. One rare (D95N) and one common (E185Q) missense alteration was identified. More detailed analyses of the E185Q polymorphism, along with a third rare variant (R215W), failed to show an association with prostate cancer. Because the 657del5 mutation was absent from the control population, we are unable to determine if this alteration predisposes to prostate cancer. However, our data does suggest that mutations within NBS1, and in particular, 657del5, do not significantly contribute to the overall prostate cancer burden within our patient samples.

RNASEL Mutation Screening and Association Study in Ashkenazi and Non-Ashkenazi Prostate Cancer Patients

Epidemiologic and genetic studies support the considerable effect of heritable factors on prostate tumorigenesis, although to date, no unequivocal susceptibility gene has been identified. The extensive study of RNASEL in prostate cancer patients worldwide has yielded conflicting results. We reevaluated the role of the RNASEL 471delAAAG Ashkenazi founder mutation in 1,642 Ashkenazi patients with prostate, bladder, breast/ovarian, and colon cancers; Ashkenazi controls; and in non-Ashkenazi prostate cancer patients and controls. The entire RNASEL coding sequence was also screened using denaturing high-performance liquid chromatography and multiplex ligation-dependent probe amplification for possible sequence variations or copy number changes in a population of prostate cancer patients. The 471delAAAG mutation was detected in 2.4% of the Ashkenazi prostate cancer patients; in 1.9% of patients with bladder, breast/ovarian, and colon cancers; and in 2.0% of the Ashkenazi controls. Seven additional variants were detected in RNASEL, including a novel potentially pathogenic splice site mutation, IVS5+1delG, although none were associated with increased prostate cancer risk. Multiplex ligation-dependent probe amplification analysis showed two RNASEL gene copies in all 300 prostate cancer patients tested. We estimated that the RNASEL 471delAAAG founder mutation, which was detected in 2% of the Ashkenazi Jews, originated between the 2nd and 5th centuries A.D., compared with the less frequent (1%) BRCA1 185delAG founder mutation, which originated hundreds of years earlier. Taken together, our analysis does not support a role for the RNASEL 471delAAAG Ashkenazi mutation nor for the other alterations detected in RNASEL in prostate cancer risk in Jewish men.

Making Sense of Prostate Specific Antigen: Improving its Predictive Value in Patients Undergoing Prostate Biopsy

PURPOSE

The clinical usefulness of PSA for prostate cancer screening is unclear, although the test remains in common use. New methods to interpret PSA are needed.

MATERIALS AND METHODS

We examined a cohort of 2,637 men who underwent prostate biopsies for abnormal DRE or PSA between 1999 and 2004. Using risk factors for prostate cancer, including patient age, ethnicity, family history of prostate cancer, previous negative biopsy, voiding symptoms and prostate volume, we developed risk groups for prostate cancer using recursive partitioning modeling independent of PSA or DRE. We then compared prostate cancer probabilities by PSA ranges by risk group.

RESULTS

Of the 2,637 men 1,282 (48.6%) had prostate cancer. Age, ethnicity, family history, previous negative biopsy and prostate volume were predictive for cancer. We constructed 6 risk groups by combining these factors and created tables to assign patients to these groups. Independent of PSA and DRE the probability of cancer ranged from 15% in patients in group 1 to 78% in patients in group 6 (p <0.0001). By adding PSA and DRE to each risk group prostate cancer probabilities were refined from 0% to 100%. Patients in the higher risk groups also had higher grade cancer (p <0.0001).

CONCLUSIONS

We generated 6 risk groups based on simple risk factors for prostate cancer. When used in the right context and patient, PSA is highly accurate for predicting prostate cancer and permitting rational decision making in patients with abnormal PSA.

RNASEL germline variants are associated with pancreatic cancer

The RNASEL (encoding ribonuclease L) gene Glu265X mutation has been implicated in familial prostate cancer, and an association between the RNASEL Arg462Gln variant and sporadic and familial prostate cancer, has also been suggested. Because prostate cancer occurs in some familial pancreatic cancer families, we evaluated the role of the RNASEL gene variants Glu265X and Arg462Gln in the etiology of pancreatic cancer. Exon 2 of the RNASEL gene was directly sequenced in the germline of 36 familial and 75 sporadic pancreatic cancer patients and in 108 controls. The Glu265X mutation was identified in one (2.8%) familial and one (1.3%) sporadic pancreatic cancer case, but not in any of the controls. Arg462Gln variants were identified in 61 (56%) controls and in 55 (73%) sporadic pancreatic cancer cases with 8 (7%) and 12 (16%) homozygotes, respectively (p = 0.009). For homozygous carriers the increased risk for pancreatic cancer was 3.5 (odds ratio [OR] = 3.53, 95% confidence interval [CI] = 1.11-11.46, p = 0.03). The population attributable fraction (PAF) was 38.7% (95% CI = 0.08-0.80). In familial pancreatic cancer no association between Arg462Gln genotypes and pancreatic cancer risk was evident. In sporadic pancreatic cancer there were no significant differences between Arg462Gln genotypes regarding clinical characteristics. In familial pancreatic cancer, however, patients with Arg462Gln variants had more aggressive tumors with more high grade cancers (OR = 15.40, p = 0.009) and more distant metastases (OR = 7.00, p = 0.04) than patients with the wild-type genotype. Our results suggest that RNASEL variants Glu265X and Arg462Gln may contribute to the tumorigenesis of sporadic and familial pancreatic cancer, which has to be proven in large scale studies.

Association of hereditary prostate cancer gene polymorphic variants with sporadic aggressive prostate carcinoma

BACKGROUND

ELAC2, MSR1, and RNASEL are candidate genes for hereditary prostate carcinoma (HPC). While, studies have demonstrated that single nucleotide polymorphisms (SNPs) in these genes are associated with sporadic disease as well as HPC, these results are often not replicated in follow-up studies. Given that the majority of patients studied had localized disease and up to 50% of localized prostate cancer is clinically insignificant, the inability to replicate the initial findings may reflect that some subjects had indolent tumors. Herein, we examine patients with metastatic disease to determine if an association exists between HPC SNPs and unambiguously significant prostate cancer.

METHODS

We examined polymorphisms within ELAC2 (S217L, A541T, E622V), MSR1 (P275A, R293X, aIVS5-59c), and RNASEL (E265X, R462Q, D541E) in 150 European-Americans with metastatic prostate cancer and 170 prostate cancer-free controls using pyrosequencing assays.

RESULTS

Only ELAC2 217L (37% cases vs. 29% controls (P=0.034)) and RNASEL 541E (61% cases vs. 53% controls (P=0.045)) were over-represented. Analysis of genotypes revealed that presence of the leucine ELAC2 allele (OR 1.54: 95% CI=0.99-2.41, SS vs. SL, LL) and homozygosity for the glutamic acid RNASEL allele (OR 1.68: 95% CI=1.04-2.70, EE vs. DE, DD) were associated with increased risk. Patients with both genotypes were of particularly high-risk (OR 2.66: 95% CI=1.36-5.19).

CONCLUSIONS

These results suggest that, in a European-American population, ELAC2 217L and RNASEL 541E are associated with metastatic sporadic disease. ELAC2 and RNASEL SNP analysis may prove useful in determining which patients are at risk for developing clinically significant prostate carcinoma.

Molecular pathology of prostate cancer

The molecular pathology of prostate cancer is complex; not only are multiple genes involved in its pathogenesis, but additional environmental factors such as diet and inflammation are also involved. The exhaustive research into prostate cancer to date has demonstrated a complex interaction of multiple genes and environmental factors, some of which may be more important in individual prostate cancer cases. This is an exciting era, with the emergence of new investigative tools such as DNA microarray technology and the application of the field of proteomics to the study of human cancers. Knowledge of genetic changes underlying the initiation, development, and progression of prostate cancer is accumulating rapidly. With increasing knowledge, it may be possible to distinguish indolent from aggressive prostate tumours by molecular fingerprinting. This review discusses the most consistently reported molecular pathological findings in hereditary and sporadic prostate cancer, together with new concepts and technologies.

Arg462Gln sequence variation in the prostate-cancer-susceptibility gene RNASEL and age of onset of hereditary non-polyposis colorectal cancer: a case-control study

BACKGROUND

RNASEL is thought to be a susceptibility gene for hereditary prostate cancer and encodes the endoribonuclease RNase L, which has a role in apoptosis and is a candidate tumour-suppressor protein. A common sequence variation in RNASEL, Arg462Gln, has been associated with hereditary and sporadic prostate cancer, and the Gln variant has about three-fold reduced RNase activity in vitro. In view of the association between the age of onset of hereditary non-polyposis colorectal cancer and functionally different variants of P53, which play a key part in the apoptotic pathway, we aimed to assess whether the Arg462Gln variation of RNASEL affects the age of onset of hereditary non-polyposis colorectal cancer.

METHODS

We screened 251 patients with hereditary non-polyposis colorectal cancer who were unrelated, had pathogenic germline mutations in MSH2 (n=141) or MLH1 (n=110), and had colorectal carcinoma as the first tumour, for variation at codon 462 of RNASEL and compared them with 439 healthy controls.

FINDINGS

The median age of onset was 40 years (range 17-75) for patients with an Arg/Arg genotype at codon 462, 37 years (13-69) for patients with an Arg/Gln genotype, and 34 years (20-49) for those with a Gln/Gln genotype (p=0.0198). Only the RNASEL genotype had a significant effect on age of onset (p=0.0062) in an additive mode of inheritance. Pair-wise comparisons between genotype groups showed that the two homozygous groups (ie, Arg/Arg vs Gln/Gln) differed significantly in age of disease onset (mean age difference 4.8 years [SD 1.7], p=0.0044).

INTERPRETATION

A sequence variation in the prostate-cancer-susceptibility gene RNASEL has a role in a different, unassociated malignant disease. Genotypes at RNASEL codon 462 are associated with age of onset of hereditary non-polyposis colorectal cancer in a dose-dependent way, and might have a role in preventive strategies for this disease.