Germline alterations of the RNASEL gene, a candidate HPC1 gene at 1q25, in patients and families with prostate cancer

Multi-omic profiling reveals an RNA processing rheostat that predisposes to prostate cancer

Prostate cancer is the most commonly diagnosed malignancy and the third leading cause of cancer deaths. GWAS have identified variants associated with prostate cancer susceptibility; however, mechanistic and functional validation of these mutations is lacking. We used CRISPR-Cas9 genome editing to introduce a missense variant identified in the ELAC2 gene, which encodes a dually localised nuclear and mitochondrial RNA processing enzyme, into the mouse Elac2 gene as well as to generate a prostate-specific knockout of Elac2. These mutations caused enlargement and inflammation of the prostate and nodule formation. The Elac2 variant or knockout mice on the background of the transgenic adenocarcinoma of the mouse prostate (TRAMP) model show that Elac2 mutation with a secondary genetic insult exacerbated the onset and progression of prostate cancer. Multiomic profiling revealed defects in energy metabolism that activated proinflammatory and tumorigenic pathways as a consequence of impaired noncoding RNA processing and reduced protein synthesis. Our physiologically relevant models show that the ELAC2 variant is a predisposing factor for prostate cancer and identify changes that underlie the pathogenesis of this cancer.

The performance of multi-gene panels for breast/ovarian cancer predisposition

BRCA1 and BRCA2 are the most mutated genes in breast cancer. We analyzed 48 breast cancer subjects using two methods that differ in terms of number of genes investigated and strategy used (primers: Panel A - 12 genes - vs probes: Panel B - 48 genes). Both the panels and procedures identified "pathogenic" or "likely pathogenic" variants in TP53, ATM, CHEK2 and BARD1 besides BRCA1 and BRCA2. Panel B identified two other putatively pathogenic variants in RNASEL and in RAD50. Identification of variants other than the BRCA genes can be useful in patient management. A total of 121 variants were distributed within the 12 genes and were correctly detected by both panels. However, the number of calls without divergence, namely ± 0.10 difference of allelic frequency, was 78.3%, while calls with a divergence below 0.10 was 16.7%, thus indicating that only 5% (n = 275) of 5,412 calls had a divergence above 0.10. Although these panels differ from each other, both are useful in different situations, particularly when patients should be tested for genes other than BRCA1/2 (as occurs in patients affected by a so called hereditary syndrome) or for therapeutic purposes.

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.

Multi-gene panel testing increases germline predisposing mutations’ detection in a cohort of breast/ovarian cancer patients from Southern Italy

Breast cancer is the most common neoplasia in females worldwide, about 10% being hereditary/familial and due to DNA variants in cancer-predisposing genes, such as the highly penetrant BRCA1/BRCA2 genes. However, their variants explain up to 25% of the suspected hereditary/familial cases. The availability of NGS methodologies has prompted research in this field. With the aim to improve the diagnostic sensitivity of molecular testing, a custom designed panel of 44 genes, including also non-coding regions and 5’ and 3’ UTR regions, was set up. Here, are reported the results obtained in a cohort of 64 patients, including also few males, from Southern Italy. All patients had a positive personal and/or familial history for breast and other cancers, but tested negative to routine BRCA analysis. After obtaining their written informed consent, a genomic DNA sample/patient was used to obtain an enriched DNA library, then analyzed by NGS. Sequencing data analysis allowed the identification of pathogenic variants in 12 of tested patients (19%). Interestingly, MUTYH was the most frequently altered gene, followed by RNASEL, ATM, MSH6, MRE11A, and PALB2 genes. The reported resultsreinforce the need for enlarged molecular testing beyond BRCA genes, at least in patients with a personal and familial history, strongly suggestive for a hereditary/familial form. This gives also a hint to pursue more specific precision oncology therapy.

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.

Template-Independent Poly(A)-Tail Decay and RNASEL as Potential Cellular Biomarkers for Prostate Cancer Development

Simple Summary

The ultimate need in cancer tissue is to adapt translation machinery to accelerated protein synthesis in a rapidly proliferating environment. Our study was designed with the aim of integrating fundamental and clinical research to find new biomarkers for prostate cancer (PC) with clinical usefulness for the stratification prediction of healthy tissue transition into malignant phenotype. This study revealed: (i) an entirely novel mechanism of the regulatory influence of Poly(A) deadenylase in mRNAs translational activity and the 3′ mRNA untranslated region (3′UTR) length in cancer tissue and its regulation by the poly(A) decay; (ii) the RNASEL interrelationship with the inflammatory pattern of PC and corresponding tumor-adjacent and healthy tissue; and (iii) the sensitivity, specificity, and predictive value of these enzymes. The proposed manuscript is based on the use of specific biochemical and immunoassay methods with the principal research adapted for the use of tissue specimens.

Abstract

The post-transcriptional messenger RNA (mRNA) decay and turnover rate of the template-independent poly(A) tail, localized at the 3′-untranslated region (3′UTR) of mRNA, have been documented among subtle mechanisms of uncontrolled cancer tissue growth. The activity of Poly(A) deadenylase and the expression pattern of RNASEL have been examined. A total of 138 prostate tissue specimens from 46 PC patients (cancer specimens, corresponding adjacent surgically healthy tissues, and in their normal counterparts, at least 2 cm from carcinoma) were used. For the stratification prediction of healthy tissue transition into malignant phenotype, the enzyme activity of tumor-adjacent tissue was considered in relation to the presence of microfocal carcinoma. More than a four-times increase in specific enzyme activity (U/L g.prot) was registered in PC on account of both the dissociation of its inhibitor and genome reprogramming. The obtained ROC curve and Youden index showed that Poly(A) deadenylase identified PC with a sensitivity of 93.5% and a specificity of 94.6%. The RNASEL expression profile was raised significantly in PC, but the sensitivity was 40.5% and specificity was 86.9%. A significantly negative correlation between PC and control tissue counterparts with a higher expression pattern in lymphocyte-infiltrated samples were reported. In conclusion, significantly upregulated Poly(A) deadenylase activity may be a checkpoint for the transition of precancerous lesion to malignancy, while RNASEL may predict chronic inflammation.

Genetic Contributions to Prostate Cancer Disparities in Men of West African Descent

Prostate cancer (PCa) is the second most frequently diagnosed malignancy and the second leading cause of death in men worldwide, after adjusting for age. According to the International Agency for Research on Cancer, continents such as North America and Europe report higher incidence of PCa; however, mortality rates are highest among men of African ancestry in the western, southern, and central regions of Africa and the Caribbean. The American Cancer Society reports, African Americans (AAs), in the United States, have a 1.7 increased incidence and 2.4 times higher mortality rate, compared to European American's (EAs). Hence, early population history in west Africa and the subsequent African Diaspora may play an important role in understanding the global disproportionate burden of PCa shared among Africans and other men of African descent. Nonetheless, disparities involved in diagnosis, treatment, and survival of PCa patients has also been correlated to socioeconomic status, education and access to healthcare. Although recent studies suggest equal PCa treatments yield equal outcomes among patients, data illuminates an unsettling reality of disparities in treatment and care in both, developed and developing countries, especially for men of African descent. Yet, even after adjusting for the effects of the aforementioned factors; racial disparities in mortality rates remain significant. This suggests that molecular and genomic factors may account for much of PCa disparities.

Exome sequencing in BRCA1-2 candidate familias: the contribution of other cancer susceptibility genes

Hereditary Breast and Ovarian Cancer (HBOC) syndrome is a condition in which the risk of breast and ovarian cancer is higher than in the general population. The prevalent pathogenesis is attributable to inactivating variants of the BRCA1-2 highly penetrant genes, however, other cancer susceptibility genes may also be involved. By Exome Sequencing (WES) we analyzed a series of 200 individuals selected for genetic testing in BRCA1-2 genes according to the updated National Comprehensive Cancer Network (NCCN) guidelines. Analysis by MLPA was performed to detect large BRCA1-2 deletions/duplications. Focusing on BRCA1-2 genes, data analysis identified 11 cases with pathogenic variants (4 in BRCA1 and 7 in BRCA1-2) and 12 with uncertain variants (7 in BRCA1 and 5 in BRCA2). Only one case was found with a large BRCA1 deletion. Whole exome analysis allowed to characterize pathogenic variants in 21 additional genes: 10 genes more traditionally associated to breast and ovarian cancer (ATM, BRIP1, CDH1, PALB2, PTEN, RAD51C, and TP53) (5% diagnostic yield) and 11 in candidate cancer susceptibility genes (DPYD, ERBB3, ERCC2, MUTYH, NQO2, NTHL1, PARK2, RAD54L, and RNASEL). In conclusion, this study allowed a personalized risk assessment and clinical surveillance in an increased number of HBOC families and to broaden the spectrum of causative variants also to candidate non-canonical genes.

The use of zebrafish model in prostate cancer therapeutic development and discovery

Zebrafish is now among the leading in vivo model for cancer research, including prostate cancer. They are an alternative economic model being used to study cancer development, proliferation, and metastasis. They can also be effectively utilized for the development of cancer drugs at all levels, including target validation, and high-throughput screening for possible lead molecules. In this review, we provide a comprehensive overview of the role of zebrafish as an in vivo model in prostate cancer research. Globally, prostate cancer is a leading cause of death in men. Although many molecular mechanisms have been identified as playing a role in the pathogenesis of prostate cancer, there is still a significant need to understand the initial events of the disease. Furthermore, current treatments are limited by the emergence of severe toxicities and multidrug resistance. There is an essential need for economical and relevant research tools to improve our understanding and overcome these problems. This review provides a comprehensive summary of studies that utilized zebrafish for different aims in prostate cancer research. We discuss the use of zebrafish in prostate cancer cell proliferation and metastasis, defining signaling pathways, drug discovery and therapeutic development against prostate cancer, and toxicity studies. Finally, this review highlights limitations in this field and future directions to efficiently use zebrafish as a robust model for prostate cancer therapeutics development.

The role of viruses in adenocarcinoma development

Cancer is a leading public health issue that accounts for million deaths around the world every year. Human cancers contain over 100 types, which are categorized into different groups. Adenocarcinoma is one of those categories of cancer that begins from the glans and involves various tissues such as lung, esophagus, pancreas, prostate and colorectal. A range of risk factors has been identified for the development and progression of adenocarcinomas. One of these risk factors are viruses that serves special mechanisms to affect important host cell factors and tumorigenic pathways, contributing in development and promotion of adenocarcinomas. Here, we summarized the main viruses and their mechanisms implicated in the course of various adenocarcinomas development.

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.

Genetic profiling as a clinical tool in advanced parathyroid carcinoma

CONTEXT

Parathyroid carcinoma (PC) is a rare endocrine malignancy with no approved systemic therapies for unresectable locally invasive or distant metastatic disease. Understanding the molecular changes in advanced PC can provide better understanding of this disease and potentially help directing targeted therapy.

OBJECTIVE

To evaluate tumor-specific genetic changes using next-generation sequencing (NGS) panels.

DESIGN

All patients with advanced PC were tested for hot-spot panels using NGS panels including a 50-gene panel, a 409-gene panel if the standard 50-gene panel (Ion Torrent, Life Technology) was negative or a FoundationOne panel.

SETTING

The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.

PATIENTS OR OTHER PARTICIPANTS

11 patients with advanced PC were selected to undergo molecular testing.

MAIN OUTCOME MEASURE(S)

Genetic profiles of advanced PC.

RESULTS

Among the 11 patients, 4 patients had the 50-gene panel only, 6 had 409-gene panel after a negative 50-gene panel and 1 had FoundationOne. One patient who had 50-gene panel only also had his metastatic site (esophagus) of his tumor tested with FoundationOne. The most common mutations identified were in the PI3 K (PIK3CA, TSC1 and ATM) (4/11 patients) and TP53 (3/11) pathways. Genes not previously reported to be mutated in PC included: SDHA, TERT promoter and DICER1. Actionable mutations were found in 54% (6/11) of the patients.

CONCLUSIONS

Mutational profiling using NGS panels in advanced PC has yielded important potentially targetable genetic alterations. Larger studies are needed to identify commonly mutated genes in advanced PC patients. Development of novel therapies targeting these cellular pathways should be considered.

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.

Defects in interferon pathways as potential biomarkers of sensitivity to oncolytic viruses

Increased sensitivity of cancer cells to viruses is a prerequisite for the success of oncolytic virotherapy. One of the major causes of such a phenotype is the disruption of innate antiviral defenses associated with dysfunction of type 1 interferons (IFNs) that permits unlimited replication of viruses in cancer cells. Defects in IFN pathways help cancer progression by providing additional advantages to tumor cells. However, while these defects promote the survival and accelerated proliferation of malignant cells, they facilitate viral replication and thus enhance the efficiency of viral oncolysis. This review describes a broad spectrum of defects in genes that participate in IFN induction and IFN response pathways. Expression levels and/or functional activities of these genes are frequently low or absent in cancer cells, making them sensitive to virus infection. Therefore, certain specific defects in IFN signaling cascades might serve as potential biomarkers to help in identifying individual cancer patients who are likely to benefit from oncolytic virotherapy.

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.

Germline BRCA mutation in male carriers-ripe for precision oncology?

BACKGROUND

Prostate cancer (PC) is one of the known heritable cancers with individual variations attributed to genetic factors. BRCA1 and BRCA2 are tumour suppressor genes with crucial roles in repairing DNA and thereby maintaining genomic integrity. Germline BRCA mutations predispose to multiple familial tumour types including PC.

METHODS

We performed a Pubmed database search along with review of reference lists from prominent articles to capture papers exploring the association between BRCA mtuations and prostate cancer risk and prognosis. Articles were retrieved until May 2017 and filtered for relevance, and publication type.

RESULTS

We explored familial PC genetics; discussed the discovery and magnitude of the association between BRCA mutations and PC risk and outcome; examined implications of factoring BRCA mutations into PC screening; and discussed the rationale for chemoprevention in this high-risk population. We confirmed that BRCA1/2 mutations confer an up to 4.5-fold and 8.3-fold increased risk of PC, respectively. BRCA2 mutations are associated with an increased risk of high-grade disease, progression to metastatic castration-resistant disease, and 5-year cancer-specific survival rates of 50 to 60%.

CONCLUSION

Despite the growing body of research on DNA repair genes, deeper analysis is needed to understand the aetiological role of germline BRCA mutations in the natural history of PC. There is a need for awareness to screen for this marker of PC risk. There is similarly an opportunity for structured PC screening programs for BRCA mutation carriers. Finally, further research is required to identify potential chemopreventive strategies for this high-risk subgroup.

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.

The common parasite Toxoplasma gondii induces prostatic inflammation and microglandular hyperplasia in a mouse model

BACKGROUND

Inflammation is the most prevalent and widespread histological finding in the human prostate, and associates with the development and progression of benign prostatic hyperplasia and prostate cancer. Several factors have been hypothesized to cause inflammation, yet the role each may play in the etiology of prostatic inflammation remains unclear. This study examined the possibility that the common protozoan parasite Toxoplasma gondii induces prostatic inflammation and reactive hyperplasia in a mouse model.

METHODS

Male mice were infected systemically with T. gondii parasites and prostatic inflammation was scored based on severity and focality of infiltrating leukocytes and epithelial hyperplasia. We characterized inflammatory cells with flow cytometry and the resulting epithelial proliferation with bromodeoxyuridine (BrdU) incorporation.

RESULTS

We found that T. gondii infects the mouse prostate within the first 14 days of infection and can establish parasite cysts that persist for at least 60 days. T. gondii infection induces a substantial and chronic inflammatory reaction in the mouse prostate characterized by monocytic and lymphocytic inflammatory infiltrate. T. gondii-induced inflammation results in reactive hyperplasia, involving basal and luminal epithelial proliferation, and the exhibition of proliferative inflammatory microglandular hyperplasia in inflamed mouse prostates.

CONCLUSIONS

This study identifies the common parasite T. gondii as a new trigger of prostatic inflammation, which we used to develop a novel mouse model of prostatic inflammation. This is the first report that T. gondii chronically encysts and induces chronic inflammation within the prostate of any species. Furthermore, T. gondii-induced prostatic inflammation persists and progresses without genetic manipulation in mice, offering a powerful new mouse model for the study of chronic prostatic inflammation and microglandular hyperplasia.

Association between variants in genes involved in the immune response and prostate cancer risk in men randomized to the finasteride arm in the Prostate Cancer Prevention Trial

BACKGROUND

We reported that some, but not all single nucleotide polymorphisms (SNPs) in select immune response genes are associated with prostate cancer, but not individually with the prevalence of intraprostatic inflammation in the Prostate Cancer Prevention Trial (PCPT) placebo arm. Here, we investigated whether these same SNPs are associated with risk of lower- and higher-grade prostate cancer in men randomized to finasteride, and with prevalence of intraprostatic inflammation among controls. Methods A total of 16 candidate SNPs in IL1β, IL2, IL4, IL6, IL8, IL10, IL12(p40), IFNG, MSR1, RNASEL, TLR4, and TNFA and 7 tagSNPs in IL10 were genotyped in 625 white prostate cancer cases, and 532 white controls negative for cancer on an end-of-study biopsy nested in the PCPT finasteride arm. We used logistic regression to estimate log-additive odds ratios (OR) and 95% confidence intervals (CI) adjusting for age and family history.

RESULTS

Minor alleles of rs2243250 (T) in IL4 (OR = 1.46, 95% CI 1.03-2.08, P-trend = 0.03), rs1800896 (G) in IL10 (OR = 0.77, 95% CI 0.61-0.96, P-trend = 0.02), rs2430561 (A) in IFNG (OR = 1.33, 95% CI 1.02-1.74; P-trend = 0.04), rs3747531 (C) in MSR1 (OR = 0.55, 95% CI 0.32-0.95; P-trend = 0.03), and possibly rs4073 (A) in IL8 (OR = 0.81, 95% CI 0.64-1.01, P-trend = 0.06) were associated with higher- (Gleason 7-10; N = 222), but not lower- (Gleason 2-6; N = 380) grade prostate cancer. In men with low PSA (<2 ng/mL), these higher-grade disease associations were attenuated and/or no longer significant, whereas associations with higher-grade disease were apparent for minor alleles of rs1800795 (C: OR = 0.70, 95% CI 0.51-0.94, P-trend = 0.02) and rs1800797 (A: OR = 0.72, 95% CI 0.53-0.98, P-trend = 0.04) in IL6. While some IL10 tagSNPs were associated with lower- and higher-grade prostate cancer, distributions of IL10 haplotypes did not differ, except possibly between higher-grade cases and controls among those with low PSA (P = 0.07). We did not observe an association between the studied SNPs and intraprostatic inflammation in the controls.

CONCLUSION

In the PCPT finasteride arm, variation in genes involved in the immune response, including possibly IL8 and IL10 as in the placebo arm, may be associated with prostate cancer, especially higher-grade disease, but not with intraprostatic inflammation. We cannot rule out PSA-associated detection bias or chance due to multiple testing.

Xenotropic Murine Leukemia Virus-Related Virus (XMRV) and the Safety of the Blood Supply

In 2006, a new virus, xenotropic murine leukemia virus-related virus (XMRV), was discovered in a cohort of U.S. men with prostate cancer. Soon after this initial finding, XMRV was also detected in samples from patients with chronic fatigue syndrome (CFS). The blood community, which is highly sensitive to the threat of emerging infectious diseases since the HIV/AIDS crisis, recommended indefinite deferral of all blood donors with a history of CFS. As XMRV research progressed, conflicting results emerged regarding the importance of this virus in the pathophysiology of prostate cancer and/or CFS. Molecular biologists traced the development of XMRV to a recombination event in a laboratory mouse that likely occurred circa 1993. The virus was propagated via cell lines derived from a tumor present in this mouse and spread through contamination of laboratory samples. Well-controlled experiments showed that detection of XMRV was due to contaminated samples and was not a marker of or a causal factor in prostate cancer or CFS. This paper traces the development of XMRV in the prostate and CFS scientific communities and explores the effect it had on the blood community.

RNase L Suppresses Androgen Receptor Signaling, Cell Migration and Matrix Metalloproteinase Activity in Prostate Cancer Cells

The interferon antiviral pathways and prostate cancer genetics converge on a regulated endoribonuclease, RNase L. Positional cloning and linkage studies mapped Hereditary Prostate Cancer 1 (HPC1) to RNASEL. To date, there is no correlation of viral infections with prostate cancer, suggesting that RNase L may play additional roles in tumor suppression. Here, we demonstrate a role of RNase L as a suppressor of androgen receptor (AR) signaling, cell migration and matrix metalloproteinase activity. Using RNase L mutants, we show that its nucleolytic activity is dispensable for both AR signaling and migration. The most prevalent HPC1-associated mutations in RNase L, R462Q and E265X, enhance AR signaling and cell migration. RNase L negatively regulates cell migration and attachment on various extracellular matrices. We demonstrate that RNase L knockdown cells promote increased cell surface expression of integrin β1 which activates Focal Adhesion Kinase-Sarcoma (FAK-Src) pathway and Ras-related C3 botulinum toxin substrate 1-guanosine triphosphatase (Rac1-GTPase) activity to increase cell migration. Activity of matrix metalloproteinase (MMP)-2 and -9 is significantly increased in cells where RNase L levels are ablated. We show that mutations in RNase L found in HPC patients may promote prostate cancer by increasing expression of AR-responsive genes and cell motility and identify novel roles of RNase L as a prostate cancer susceptibility gene.

RNase L is a negative regulator of cell migration

RNase L is a regulated endoribonuclease that functions in the interferon antiviral response. Activation of RNase L by 2', 5'-oligoadenylates has been linked to apoptosis, autophagy and inflammation. Genetic studies have also suggested the possible involvement of the RNase L gene (RNASEL) on chromosome 1q25.3 in several types of cancer. Here we report that ablation of RNase L in human prostate cancer PC3 cells by CRISPR/Cas9 gene editing technology enhanced cell migration as determined both by transwell assays and scratch wound healing assays. In addition, RNase L knockdown by means of RNAi increased migration of PC3 and DU145 cells in response to either fibronectin or serum stimulation, as did homozygous disruption of the RNase L gene in mouse embryonic fibroblasts. Serum or fibronectin stimulation of focal adhesion kinase (FAK) autophosphorylation on tyrosine-397 was increased by either knockdown or ablation of RNase L. In contrast, a missense mutant RNase L (R667A) lacking catalytic activity failed to suppress cell migration in PC3 cells. However, a nuclease-inactive mutant mouse RNase L (W630A) was able to partially inhibit migration of mouse fibroblasts. Consistent with a role for the catalytic activity of RNase L, transfection of PC3 cells with the RNase L activator, 2', 5'-oligoadenylate, suppressed cell migration. RNase L knockdown in PC3 cells enhanced tumor growth and metastasis following implantation in the mouse prostate. Our results suggest that naturally occurring mutations in the RNase L gene might promote enhanced cell migration and metastasis.

New advances in our understanding of the "unique" RNase L in host pathogen interaction and immune signaling

Ever since the discovery of the existence of an interferon (IFN)-regulated ribonuclease, significant advances have been made in understanding the mechanism and associated regulatory effects of its action. What had been studied initially as a "unique" endoribonuclease is currently known as ribonuclease L (RNase L where "L" stands for latent). Some of the key developments include discovery of the RNase L signaling pathway, its structural characterization, and its molecular cloning. RNase L has been implicated in antiviral and antibacterial defense, as well as in hereditary prostate cancer. RNase L is activated by 2'-5' linked oligoadenylates (2-5A), which are synthesized by the oligoadenylate synthetases (OASs), a family of IFN-regulated pathogen recognition receptors that sense double-stranded RNAs. Activated RNase L cleaves single stranded RNAs, including viral RNAs and cellular RNAs. The catalytic activity of RNase L has been found to lead into the activation of several cellular signaling pathways, including those involved in autophagy, apoptosis, IFN-β production, NLRP3 inflammasome activation leading to IL-1β secretion, inhibition of cell migration, and cell adhesion. In this review, we will highlight the newest advances in our understanding of the catalytic role of RNase L in the context of different cellular pathways and extend the scope of these findings to discussion of potential therapeutic targets for antimicrobial drug development.

RNaseH2A is involved in human gliomagenesis through the regulation of cell proliferation and apoptosis

Mutations in the RNaseH2A gene are involved in Aicardi‑Goutieres syndrome, an autosomal recessive neurological dysfunction; however, studies assessing RNaseH2A in relation to glioma are scarce. This study aimed to assess the role of RNaseH2A in glioma and to unveil the underlying mechanisms. RNaseH2A was silenced in glioblastoma cell lines U87 and U251. Gene expression was assessed in the cells transfected with RNaseH2A shRNA or scramble shRNA by microarrays, validated by quantitative real time PCR. Protein expression was evaluated by western blot analysis. Cell proliferation was assessed by the MTT assay; cell cycle distribution and apoptosis were analyzed by flow cytometry. Finally, the effects of RNaseH2A on colony formation and tumorigenicity were assessed in vitro and in a mouse xenograft model, respectively. RNaseH2A was successively knocked down in U87 and U251 cells. Notably, RNaseH2A silencing resulted in impaired cell proliferation, with 70.7 and 57.8% reduction in the U87 and U251 cells, respectively, with the cell cycle being blocked in the G0/G1 phase in vitro. Meanwhile, clone formation was significantly reduced by RNaseH2A knockdown, which also increased cell apoptosis by approximately 4.5-fold. In nude mice, tumor size was significantly decreased after RNaseH2A knockdown: 219.29±246.43 vs. 1160.26±222.61 mm3 for the control group; similar findings were obtained for tumor weight (0.261±0.245 and 1.127±0.232 g) in the shRNA and control groups, respectively). In the microarray data, RNaseH2A was shown to modulate several signaling pathways responsible for cell proliferation and apoptosis, such as IL-6 and FAS pathways. RNaseH2A may be involved in human gliomagenesis, likely by regulating signaling pathways responsible for cell proliferation and apoptosis.

Xenotropic Murine Leukemia Virus-Related Virus and RNase L R462Q Variants in Iranian Patients With Sporadic Prostate Cancer

Background:

Although several studies have confirmed the association of xenotropic murine leukemia virus-related virus (XMRV) and prostate cancer, this association is still controversial, as most studies did not detect XMRV in prostate tissue samples. Furthermore, some genetic and epidemiological studies have highlighted a role for RNase L polymorphisms, particularly R462Q, in the progression of prostate cancer.

Objectives:

The focus of this study was on the association of XMRV and RNase L R462Q variants with the risk of prostate cancer in Iranian patients.

Patients and Methods:

In this case-control study, 40 and 80 individuals with sporadic prostate cancer and benign prostatic hyperplasia, respectively, were included. The presence of XMRV was evaluated by real-time polymerase chain reaction (PCR) of integrase and nested-PCR for the gag genes. The RNase L R462Q polymorphism analysis was carried out by PCR and sequencing.

Results:

In a total of 40 sporadic prostate cancer and 80 benign prostatic hyperplasia cases, no XMRV was detected by real-time PCR and nested-PCR. RNase L R462Q polymorphism analysis reveals that although there was an increase in the risk of prostate cancer correlated with the Q/Q allele of RNase L at position 462, the frequencies of the RNase L R462Q alleles were not statistically significant between the prostate cancer and benign prostatic hyperplasia groups (OR = 2.75 (95% CI = 0.67 - 11.3), P = 0.29).

Conclusions:

These results did not support the presence of XMRV in the samples with prostate cancer and showed that RNase L R462Q variants had relatively little or no impact on the risk of prostate cancer in Iranian population.

Polyomavirus BK and prostate cancer: a complex interaction of potential clinical relevance

Several studies associating BK polyomavirus (BKPyV) and prostate cancer (PCa) suggested that this virus may exert its oncogenic activity at early stages of cancer development. The BKPyV oncogene, the large T antigen (LTag), has frequently been detected in areas of proliferative inflammatory atrophy, which is considered a precursor lesion leading to prostatic intraepithelial neoplasia and overt PCa. In a recently updated systematic review, the presence of BKPyV was significantly higher in PCa tissues than in healthy control tissues, providing an indication for a link between BKPyV infection and cancer risk. In addition, recent original investigations highlighted an association between expression of the virus and the clinical course of PCa. For example, by studying immune responses elicited against BKPyV LTag, a significant association between LTag positive cancer lesions and a peculiar regulatory profiling has been observed in PCa patients with evidence of disease recurrence after surgical radical prostatectomy. Lastly, a study carried out in a larger cohort of patients undergoing radical prostatectomy revealed the IgG response against LTag as an independent predictor of disease recurrence. Although a full picture of the mechanisms potentially responsible for the involvement of BKPyV in PCa is not available yet, continuing work on this topic should help to refine the potential role of BKPyV in PCa patients, perhaps revealing unsuspected associations with the clinical course of this disease.

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.

Interleukin-driven insulin-like growth factor promotes prostatic inflammatory hyperplasia

Prostatic inflammation is of considerable importance to urologic research because of its association with benign prostatic hyperplasia and prostate cancer. However, the mechanisms by which inflammation leads to proliferation and growth remain obscure. Here, we show that insulin-like growth factors (IGFs), previously known as critical developmental growth factors during prostate organogenesis, are induced by inflammation as part of the proliferative recovery to inflammation. Using genetic models and in vivo IGF receptor blockade, we demonstrate that the hyperplastic response to inflammation depends on interleukin-1-driven IGF signaling. We show that human prostatic hyperplasia is associated with IGF pathway activation specifically localized to foci of inflammation. This demonstrates that mechanisms of inflammation-induced epithelial proliferation and hyperplasia involve the induction of developmental growth factors, further establishing a link between inflammatory and developmental signals and providing a mechanistic basis for the management of proliferative diseases by IGF pathway modulation.

Identification of four novel genes contributing to familial elevated plasma HDL cholesterol in humans

While genetic determinants strongly influence HDL cholesterol (HDLc) levels, most genetic causes underlying variation in HDLc remain unknown. We aimed to identify novel rare mutations with large effects in candidate genes contributing to extreme HDLc in humans, utilizing family-based Mendelian genetics. We performed next-generation sequencing of 456 candidate HDLc-regulating genes in 200 unrelated probands with extremely low (≤10th percentile) or high (≥90th percentile) HDLc. Probands were excluded if known mutations existed in the established HDLc-regulating genes ABCA1, APOA1, LCAT, cholesteryl ester transfer protein (CETP), endothelial lipase (LIPG), and UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 2 (GALNT2). We identified 93 novel coding or splice-site variants in 72 candidate genes. Each variant was genotyped in the proband's family. Family-based association analyses were performed for variants with sufficient power to detect significance at P < 0.05 with a total of 627 family members being assessed. Mutations in the genes glucokinase regulatory protein (GCKR), RNase L (RNASEL), leukocyte immunoglobulin-like receptor 3 (LILRA3), and dynein axonemal heavy chain 10 (DNAH10) segregated with elevated HDLc levels in families, while no mutations associated with low HDLc. Taken together, we have identified mutations in four novel genes that may play a role in regulating HDLc levels in humans.

Interferons and their stimulated genes in the tumor microenvironment

Constitutive expression of interferons (IFNs) and activation of their signaling pathways have pivotal roles in host responses to malignant cells in the tumor microenvironment. IFNs are induced by the innate immune system and in tumors through stimulation of Toll-like receptors (TLRs) and through other signaling pathways in response to specific cytokines. Although in the oncologic context IFNs have been thought of more as exogenous pharmaceuticals, the autocrine and paracrine actions of endogenous IFNs probably have even more critical effects on neoplastic disease outcomes. Through high-affinity cell surface receptors, IFNs modulate transcriptional signaling, leading to regulation of more than 2,000 genes with varying patterns of temporal expression. Induction of the gene products by both unphosphorylated and phosphorylated STAT1 after ligand binding results in alterations in tumor cell survival, inhibition of angiogenesis, and augmentation of actions of T, natural killer (NK), and dendritic cells. The interferon-stimulated gene (ISG) signature can be a favorable biomarker of immune response but, in a seemingly paradoxical finding, a specific subset of the full ISG signature indicates an unfavorable response to DNA-damaging interventions such as radiation. IFNs in the tumor microenvironment thus can alter the emergence, progression, and regression of malignancies.

Systematic review and meta-analysis of candidate gene association studies of lower urinary tract symptoms in men

Context

Although family studies have shown that male lower urinary tract symptoms (LUTS) are highly heritable, no systematic review exists of genetic polymorphisms tested for association with LUTS.

Objective

To systematically review and meta-analyze studies assessing candidate polymorphisms/genes tested for an association with LUTS, and to assess the strength, consistency, and potential for bias among pooled associations.

Evidence acquisition

A systematic search of the PubMed and HuGE databases as well as abstracts of major urologic meetings was performed through to January 2013. Case-control studies reporting genetic associations in men with LUTS were included. Reviewers independently and in duplicate screened titles, abstracts, and full texts to determine eligibility, abstracted data, and assessed the credibility of pooled associations according to the interim Venice criteria. Authors were contacted for clarifications if needed. Meta-analyses were performed for variants assessed in more than two studies.

Evidence synthesis

We identified 74 eligible studies containing data on 70 different genes. A total of 35 meta-analyses were performed with statistical significance in five (ACE, ELAC2, GSTM1, TERT, and VDR). The heterogeneity was high in three of these meta-analyses. The rs731236 variant of the vitamin D receptor had a protective effect for LUTS (odds ratio: 0.64; 95% confidence interval, 0.49–0.83) with moderate heterogeneity (I² = 27.2%). No evidence for publication bias was identified. Limitations include wide-ranging phenotype definitions for LUTS and limited power in most meta-analyses to detect smaller effect sizes.

Conclusions

Few putative genetic risk variants have been reliably replicated across populations. We found consistent evidence of a reduced risk of LUTS associated with the common rs731236 variant of the vitamin D receptor gene in our meta-analyses.

Patient summary

Combining the results from all previous studies of genetic variants that may cause urinary symptoms in men, we found significant variants in five genes. Only one, a variant of the vitamin D receptor, was consistently protective across different populations.

Association of RNASEL and 8q24 variants with the presence and aggressiveness of hereditary and sporadic prostate cancer in a Hispanic population

To study the association between the polymorphisms Arg462Gln and Asp541Glu from the RNASEL gene (1q25), and the polymorphisms rs620861, rs1447295, rs6983267, rs7837328 from the chromosome 8q24 with the risk of presenting prostate cancer (PCa) and its clinical characteristics in a Hispanic (Chilean) population. The study was performed on 21 control patients and 83 patients diagnosed with PCa. Polymorphisms were analysed from blood samples through real-time PCR by using TaqMan probes, and the genetic analysis was performed with the SNPStats program. Also, a comparison was performed between clinical characteristics of PCa and the presence of the different polymorphism genotypes by using the Minitab software. There was a significant association between the genotype G/G from the polymorphism rs6983267 with an overall increased risk of PCa, in patients both with or without family history of PCa (OR = 4.47, 95% CI = 1.05-18.94, P = 0.034 and OR = 3.57, 95% CI = 0.96-13.35, P = 0.037, respectively). Regarding clinical parameters, patients carrying the genotype C/C from the polymorphism Asp541Glu had significantly higher prostate-specific antigen (PSA) levels than patients carrying the other genotypes (P = 0.034). Moreover, patients with the genotype G/G of rs6983267 had higher PSA levels (P = 0.024). The polymorphism rs6983267 from region 3 of the chromosome 8q24 appears to be a prominent risk factor for PCa and a biomarker for cancer aggressiveness in the group of patients who presented higher levels of PSA at the time of diagnosis.

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.

In Vitro Assessment of the Inflammatory Breast Cancer Cell Line SUM 149: Discovery of 2 Single Nucleotide Polymorphisms in the RNase L Gene

Background: Inflammatory breast cancer (IBC) is a rare, highly aggressive form of breast cancer. The mechanism of IBC carcinogenesis remains unknown. We sought to evaluate potential genetic risk factors for IBC and whether or not the IBC cell lines SUM149 and SUM190 demonstrated evidence of viral infection.

Methods: We performed single nucleotide polymorphism (SNP) genotyping for 2 variants of the ribonuclease (RNase) L gene that have been correlated with the risk of prostate cancer due to a possible viral etiology. We evaluated dose-response to treatment with interferon-alpha (IFN-α); and assayed for evidence of the putative human mammary tumor virus (HMTV, which has been implicated in IBC) in SUM149 cells. A bioinformatic analysis was performed to evaluate expression of RNase L in IBC and non-IBC.

Results: 2 of 2 IBC cell lines were homozygous for RNase L common missense variants 462 and 541; whereas 2 of 10 non-IBC cell lines were homozygous positive for the 462 variant (p= 0.09) and 0 of 10 non-IBC cell lines were homozygous positive for the 541 variant (p = 0.015). Our real-time polymerase chain reaction (RT-PCR) and Southern blot analysis for sequences of HMTV revealed no evidence of the putative viral genome.

Conclusion: We discovered 2 SNPs in the RNase L gene that were homozygously present in IBC cell lines. The 462 variant was absent in non-IBC lines. Our discovery of these SNPs present in IBC cell lines suggests a possible biomarker for risk of IBC. We found no evidence of HMTV in SUM149 cells. A query of a panel of human IBC and non-IBC samples showed no difference in RNase L expression. Further studies of the RNase L 462 and 541 variants in IBC tissues are warranted to validate our in vitro findings.

Short communication: RNASEL alleles and susceptibility to infection by human retroviruses and hepatitis viruses

RNASEL seems to function as an intracellular restriction factor blocking the establishment of infections caused by viral agents. Herein, we investigated whether allelic variants at the RNASEL gene might influence the susceptibility to viral infections or conditions potentially linked to viral agents. The allelic distribution at codon 462 was 139 (33.9%), 204 (49.8%), and 67 (16.3%) for RR, RQ, and QQ, respectively, in 410 individuals in Spain. There were no significant differences comparing 105 blood donors and 71 patients with HIV-1 infection, 27 with chronic hepatitis C, 67 with prostate cancer, and 107 with chronic fatigue syndrome. In contrast, two-thirds of 18 patients with HTLV-1 infection and 15 with chronic hepatitis B harbored RR. Thus, polymorphisms at the RNASEL gene do not seem to influence the susceptibility to common viral infections or conditions potentially of viral etiology. The role in influencing the susceptibility to HTLV-1 or HBV chronic infection warrants further examination in larger patient populations.

The association of elevated 2',5'-oligoadenylate-dependent RNase L with lung cancer correlated with deficient enzymatic activity and decreased capacity of RNase L dimerization

RNase L mediates critical cellular functions including antiviral, proapoptotic, antiproliferative and tumor suppressive activities. In this study, the expression and function of RNase L in lung cancer cells were examined. Interestingly we have found that the expression of RNase L in lung cancer cells was 3- and 9-fold higher in its mRNA and protein levels, but a significant decrease of its enzymatic activity when compared to that in corresponding normal lung cells. Further investigation revealed that 2-5A-induced dimerization of the RNase L protein, a necessary prerequisite for activation of RNase L, was inhibited, as a result of that RLI, a specific inhibitor of RNase L, was remarkably up-regulated in the cancer cells. Our findings provide new insight into how cancer cells escape normal growth-regulating mechanisms to form a tumor and the information may be useful for the design of novel strategies for treating lung cancer through regulating RNase L activity.

[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.

Positive selection on the gene RNASEL: correlation between patterns of evolution and function

RNASEL is a 2-5A-dependent endoribonuclease that is a component of the interferon-induced 2-5A system, which plays a crucial role in the antiviral and apoptotic activities of interferons. In humans, many polymorphic sites within the RNASEL gene have been associated with an increased risk of developing prostate cancer. Here, we obtained coding sequences for the RNASEL gene from 11 primates and found evidence that positive selection has operated on the C-terminal endoribonuclease domain and the N-terminal ankyrin repeats domain of the protein, domains that directly interact with virus (i.e., ankyrin repeats are responsible for receiving environmental signals, and the endoribonuclease catalyses the destruction of the pathogenic viral RNA). To extend this finding, we studied variation within this gene in modern human populations by resequencing alleles from 144 individuals representing four separate populations. Interestingly, the frequency of the 541D allele shows a negative association with the incidence rate of prostate cancer in worldwide populations, and haplotypes containing the 541D polymorphisms demonstrate signatures of positive selection. RNASEL variants having the 541D haplotype likely have a greater ability to defend against infections by viruses, thus the loss of this activity may be associated with the development of prostate cancer. We provide evidence that positive selection has operated on the RNASEL gene, and its evolution is correlated with its function in pathogen defense and cancer association.

Genetic ancestry, self-reported race and ethnicity in African Americans and European Americans in the PCaP cohort

Background

Family history and African-American race are important risk factors for both prostate cancer (CaP) incidence and aggressiveness. When studying complex diseases such as CaP that have a heritable component, chances of finding true disease susceptibility alleles can be increased by accounting for genetic ancestry within the population investigated. Race, ethnicity and ancestry were studied in a geographically diverse cohort of men with newly diagnosed CaP.

Methods

Individual ancestry (IA) was estimated in the population-based North Carolina and Louisiana Prostate Cancer Project (PCaP), a cohort of 2,106 incident CaP cases (2063 with complete ethnicity information) comprising roughly equal numbers of research subjects reporting as Black/African American (AA) or European American/Caucasian/Caucasian American/White (EA) from North Carolina or Louisiana. Mean genome wide individual ancestry estimates of percent African, European and Asian were obtained and tested for differences by state and ethnicity (Cajun and/or Creole and Hispanic/Latino) using multivariate analysis of variance models. Principal components (PC) were compared to assess differences in genetic composition by self-reported race and ethnicity between and within states.

Results

Mean individual ancestries differed by state for self-reporting AA (p = 0.03) and EA (p = 0.001). This geographic difference attenuated for AAs who answered “no” to all ethnicity membership questions (non-ethnic research subjects; p = 0.78) but not EA research subjects, p = 0.002. Mean ancestry estimates of self-identified AA Louisiana research subjects for each ethnic group; Cajun only, Creole only and both Cajun and Creole differed significantly from self-identified non-ethnic AA Louisiana research subjects. These ethnicity differences were not seen in those who self-identified as EA.

Conclusions

Mean IA differed by race between states, elucidating a potential contributing factor to these differences in AA research participants: self-reported ethnicity. Accurately accounting for genetic admixture in this cohort is essential for future analyses of the genetic and environmental contributions to CaP.

Role of epigenetics in cancer health disparities

Cancer disparities in incidence and death rates exist among various racial and ethnic groups. These disparities are thought to be due to socioeconomic status, culture, diet, stress, the environment, and biology. Biological functions, such as epigenetic processes, are affected by all these causal factors and extend throughout the life course. Epigenetic processes, in particular DNA methylation, may play a role in the induction of phenotypes with increased cancer risk due to exposure to these multiple factors. DNA methylation is known to cause changes in gene expression of key regulatory genes in cancer. There are limited studies in which epigenetic changes have been explored to address cancer disparities in various racial and ethnic populations. These few studies have reported significant epigenetic differences in various racial and ethnic groups that could account for the differences seen in tumor initiation, progression, aggressiveness, and outcome of these cancers. Genes differentially methylated among these racially and ethnically diverse populations were involved in important cellular functions, such as tumor growth, tumor suppression, hormone receptors, and genes involved in tumor metastasis. Epigenetic research with the advancement in technology has helped identify biomarkers, therapeutic targets, and understand cancer causation in the general population. Unfortunately, these advances in technology have not been applied to explore the basis for cancer health disparities. More research in epigenetics is needed that will enhance our understanding of the determinants of cancer across various diverse populations and ultimately reduce cancer health disparities.

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.

Predictive value in the analysis of RNASEL genotypes in relation to prostate cancer

BACKGROUND

We would like to compare the different RNASEL genotypes with the stage of the cancer using parameters such as PSA levels, Gleason score and T-stage, and to develop a clinical protocol for the monitoring of the disease for trying a better evolution of the patient.

METHODS

A total of 231 patients with sporadic prostate cancer and 100 of controls were genotyped in RNASEL gene by sequencing the exons 1 and 3. A survey of clinical information was collected by a specialist following the Helsinki protocol. All patients and controls were interviewed by a researcher and signed their informed consent to participation in the study, which was approved by Ethics Committee of the hospital. The genetic information was processed and collected with an ABI PRISM Genetic Analyser 3130 using SeqScape software v.2.6. All the patients were analysed by comparing the genetic and clinical data. χ(2)-tests, Monte Carlo, Fisher tests and contigency tables were performed using SPSS v.15.0 and ARLEQUIN v.3.5 software on patient population.

RESULTS

Significant differences were found only between patients and controls in D541E, R461Q and I97L genotypes, the remainder of the variants did not seem relevant to our population in contrast to other populations, such as north-Caucasians, Afro Americans and Ashkenazi Jews. The genotypes associated with the worst prognoses are G/G in D541E, A/A in R462Q and A/G in I97L. The controls were included in our study to determine an approximation of the genotype in our population compared with the patients, but they did not account for the statistical process.

CONCLUSIONS

The genetic profile of patients with this cancer combined with other parameters could be used as a prognosis factor in deciding to give more radical and frequent treatments, depending on personal genotype.

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.

XMRV Discovery and Prostate Cancer-Related Research

Xenotropic murine leukemia virus-related virus (XMRV) was first reported in 2006 in a study of human prostate cancer patients with genetic variants of the antiviral enzyme, RNase L. Subsequent investigations in North America, Europe, Asia, and Africa have either observed or failed to detect XMRV in patients (prostate cancer, chronic fatigue syndrome-myalgic encephalomyelitis (CFS-ME), and immunosuppressed with respiratory tract infections) or normal, healthy, control individuals. The principal confounding factors are the near ubiquitous presence of mouse-derived reagents, antibodies and cells, and often XMRV itself, in laboratories. XMRV infects and replicates well in many human cell lines, but especially in certain prostate cancer cell lines. XMRV also traffics to prostate in a nonhuman primate model of infection. Here, we will review the discovery of XMRV and then focus on prostate cancer-related research involving this intriguing virus.