RNASEL germline variants are associated with pancreatic cancer

CRISPR/Cas9 model of prostate cancer identifies Kmt2c deficiency as a metastatic driver by Odam/Cabs1 gene cluster expression

Metastatic prostate cancer (PCa) poses a significant therapeutic challenge with high mortality rates. Utilizing CRISPR-Cas9 in vivo, we target five potential tumor suppressor genes (Pten, Trp53, Rb1, Stk11, and RnaseL) in the mouse prostate, reaching humane endpoint after eight weeks without metastasis. By further depleting three epigenetic factors (Kmt2c, Kmt2d, and Zbtb16), lung metastases are present in all mice. While whole genome sequencing reveals few mutations in coding sequence, RNA sequencing shows significant dysregulation, especially in a conserved genomic region at chr5qE1 regulated by KMT2C. Depleting Odam and Cabs1 in this region prevents metastasis. Notably, the gene expression signatures, resulting from our study, predict progression-free and overall survival and distinguish primary and metastatic human prostate cancer. This study emphasizes positive genetic interactions between classical tumor suppressor genes and epigenetic modulators in metastatic PCa progression, offering insights into potential treatments.

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.

Identification of Key Deregulated RNA-Binding Proteins in Pancreatic Cancer by Meta-Analysis and Prediction of Their Role as Modulators of Oncogenesis

RNA-binding proteins (RBPs) play a significant role in multiple cellular processes with their deregulations strongly associated with cancer. However, there are not adequate evidences regarding global alteration and functions of RBPs in pancreatic cancer, interrogated in a systematic manner. In this study, we have prepared an exhaustive list of RBPs from multiple sources, downloaded gene expression microarray data from a total of 241 pancreatic tumors and 124 normal pancreatic tissues, performed a meta-analysis, and obtained differentially expressed RBPs (DE-RBPs) using the Limma package of R Bioconductor. The results were validated in microarray datasets and the Cancer Genome Atlas (TCGA) RNA sequencing dataset for pancreatic adenocarcinoma (PAAD). Pathway enrichment analysis was performed using DE-RBPs, and we also constructed the protein-protein interaction (PPI) network to detect key modules and hub-RBPs. Coding and noncoding targets for top altered and hub RBPs were identified, and altered pathways modulated by these targets were also investigated. Our meta-analysis identified 45 upregulated and 15 downregulated RBPs as differentially expressed in pancreatic cancer, and pathway enrichment analysis demonstrated their important contribution in tumor development. As a result of PPI network analysis, 26 hub RBPs were detected and coding and noncoding targets for all these RBPs were categorized. Functional exploration characterized the pathways related to epithelial-to-mesenchymal transition (EMT), cell migration, and metastasis to emerge as major pathways interfered by the targets of these RBPs. Our study identified a unique meta-signature of 26 hub-RBPs to primarily modulate pancreatic tumor cell migration and metastasis in pancreatic cancer. IGF2BP3, ISG20, NIP7, PRDX1, RCC2, RUVBL1, SNRPD1, PAIP2B, and SIDT2 were found to play the most prominent role in the regulation of EMT in the process. The findings not only contribute to understand the biology of RBPs in pancreatic cancer but also to evaluate their candidature as possible therapeutic targets.

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.

Biomarker microRNAs for prostate cancer metastasis: screened with a network vulnerability analysis model

Background

Prostate cancer (PCa) is a fatal malignant tumor among males in the world and the metastasis is a leading cause for PCa death. Biomarkers are therefore urgently needed to detect PCa metastatic signature at the early time. MicroRNAs are small non-coding RNAs with the potential to be biomarkers for disease prediction. In addition, computer-aided biomarker discovery is now becoming an attractive paradigm for precision diagnosis and prognosis of complex diseases.

Methods

In this study, we identified key microRNAs as biomarkers for predicting PCa metastasis based on network vulnerability analysis. We first extracted microRNAs and mRNAs that were differentially expressed between primary PCa and metastatic PCa (MPCa) samples. Then we constructed the MPCa-specific microRNA-mRNA network and screened microRNA biomarkers by a novel bioinformatics model. The model emphasized the characterization of systems stability changes and the network vulnerability with three measurements, i.e. the structurally single-line regulation, the functional importance of microRNA targets and the percentage of transcription factor genes in microRNA unique targets.

Results

With this model, we identified five microRNAs as putative biomarkers for PCa metastasis. Among them, miR-101-3p and miR-145-5p have been previously reported as biomarkers for PCa metastasis and the remaining three, i.e. miR-204-5p, miR-198 and miR-152, were screened as novel biomarkers for PCa metastasis. The results were further confirmed by the assessment of their predictive power and biological function analysis.

Conclusions

Five microRNAs were identified as candidate biomarkers for predicting PCa metastasis based on our network vulnerability analysis model. The prediction performance, literature exploration and functional enrichment analysis convinced our findings. This novel bioinformatics model could be applied to biomarker discovery for other complex diseases.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1506-7) contains supplementary material, which is available to authorized users.

Sex-specific effect of RNASEL rs486907 and miR-146a rs2910164 polymorphisms' interaction as a susceptibility factor for melanoma skin cancer

The genetics of melanoma is complex and, in addition to environmental influences, numerous genes are involved or contribute toward melanoma predisposition. In this study, we evaluated the possible interaction between miR-146a and one of its putative targets ribonuclease L (RNASEL) in the risk of sporadic melanoma. Polymorphisms rs2910164 in miR-146a and rs486907 in the RNASEL gene have both independently been associated with the risk of different cancers, and an interaction between them has been observed in nonmelanoma skin cancer. Polymorphisms rs2910164 G/C and rs486907 A/G were genotyped by restriction fragment length polymorphism analysis in 304 sporadic melanoma patients and 314 control individuals. Genotype distribution between cases and controls for each of the two polymorphisms was compared using Fisher's exact test. Epistasis between the two polymorphisms was tested by a logistic regression model. In the present study, we observed a sex-specific effect of the miR-146a rs2910164 C allele restricted to individuals carrying the RNASEL rs486907 A allele as well. Men carrying this allelic combination have the highest risk of melanoma, whereas it seems to have no effect or even an opposite relationship to melanoma risk in the female population. The results reported in the present study suggest a sex-specific interaction between miR-146a and RNASEL genes in melanoma skin cancer susceptibility, and could account for possible discordant results in association studies when stratification according to sex is not performed.

Is RNASEL:p.Glu265* a modifier of early-onset breast cancer risk for carriers of high-risk mutations?

Background

Breast cancer risk for BRCA1 and BRCA2 pathogenic mutation carriers is modified by risk factors that cluster in families, including genetic modifiers of risk. We considered genetic modifiers of risk for carriers of high-risk mutations in other breast cancer susceptibility genes.

Methods

In a family known to carry the high-risk mutation PALB2:c.3113G>A (p.Trp1038*), whole-exome sequencing was performed on germline DNA from four affected women, three of whom were mutation carriers.

Results

RNASEL:p.Glu265* was identified in one of the PALB2 carriers who had two primary invasive breast cancer diagnoses before 50 years. Gene-panel testing of BRCA1, BRCA2, PALB2 and RNASEL in the Australian Breast Cancer Family Registry identified five carriers of RNASEL:p.Glu265* in 591 early onset breast cancer cases. Three of the five women (60%) carrying RNASEL:p.Glu265* also carried a pathogenic mutation in a breast cancer susceptibility gene compared with 30 carriers of pathogenic mutations in the 586 non-carriers of RNASEL:p.Glu265* (5%) (p < 0.002). Taqman genotyping demonstrated that the allele frequency of RNASEL:p.Glu265* was similar in affected and unaffected Australian women, consistent with other populations.

Conclusion

Our study suggests that RNASEL:p.Glu265* may be a genetic modifier of risk for early-onset breast cancer predisposition in carriers of high-risk mutations. Much larger case-case and case-control studies are warranted to test the association observed in this report.

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.

RNASEL and MIR146A SNP-SNP interaction as a susceptibility factor for non-melanoma skin cancer

Immunity and inflammatory pathways are important in the genesis of non-melanoma skin cancers (NMSC). Functional genetic variation in immune modulators has the potential to affect disease etiology. We investigated associations between common variants in two key regulators, MIR146A and RNASEL, and their relation to NMSCs. Using a large population-based case-control study of basal cell (BCC) and squamous cell carcinoma (SCC), we investigated the impact of MIR146A SNP rs2910164 on cancer risk, and interaction with a SNP in one of its putative targets (RNASEL, rs486907). To examine associations between genotype and BCC and SCC, occurrence odds ratios (OR) and 95% confidence intervals (95%CI) were calculated using unconditional logistic regression, accounting for multiple confounding factors. We did not observe an overall change in the odds ratios for SCC or BCC among individuals carrying either of the RNASEL or MIR146A variants compared with those who were wild type at these loci. However, there was a sex-specific association between BCC and MIR146A in women (ORGC = 0.73, [95%CI = 0.52-1.03]; ORCC = 0.29, [95% CI = 0.14-0.61], p-trend<0.001), and a reduction in risk, albeit not statistically significant, associated with RNASEL and SCC in men (ORAG = 0.88, [95%CI = 0.65-1.19]; ORAA = 0.68, [95%CI = 0.43-1.08], p-trend = 0.10). Most striking was the strong interaction between the two genes. Among individuals carrying variant alleles of both rs2910164 and rs486907, we observed inverse relationships with SCC (ORSCC = 0.56, [95%CI = 0.38-0.81], p-interaction = 0.012) and BCC (ORBCC = 0.57, [95%CI = 0.40-0.80], p-interaction = 0.005). Our results suggest that genetic variation in immune and inflammatory regulators may influence susceptibility to NMSC, and novel SNP-SNP interaction for a microRNA and its target. These data suggest that RNASEL, an enzyme involved in RNA turnover, is controlled by miR-146a and may be important in NMSC etiology.

RNase L restricts the mobility of engineered retrotransposons in cultured human cells

Retrotransposons are mobile genetic elements, and their mobility can lead to genomic instability. Retrotransposon insertions are associated with a diverse range of sporadic diseases, including cancer. Thus, it is not a surprise that multiple host defense mechanisms suppress retrotransposition. The 2′,5′-oligoadenylate (2-5A) synthetase (OAS)-RNase L system is a mechanism for restricting viral infections during the interferon antiviral response. Here, we investigated a potential role for the OAS-RNase L system in the restriction of retrotransposons. Expression of wild type (WT) and a constitutively active form of RNase L (NΔ385), but not a catalytically inactive RNase L mutant (R667A), impaired the mobility of engineered human LINE-1 (L1) and mouse intracisternal A-type particle retrotransposons in cultured human cells. Furthermore, WT RNase L, but not an inactive RNase L mutant (R667A), reduced L1 RNA levels and subsequent expression of the L1-encoded proteins (ORF1p and ORF2p). Consistently, confocal immunofluorescent microscopy demonstrated that WT RNase L, but not RNase L R667A, prevented formation of L1 cytoplasmic foci. Finally, siRNA-mediated depletion of endogenous RNase L in a human ovarian cancer cell line (Hey1b) increased the levels of L1 retrotransposition by ∼2-fold. Together, these data suggest that RNase L might function as a suppressor of structurally distinct retrotransposons.

Familial pancreatic cancer: current status

The term 'familial pancreatic cancer (FPC) defines families with at least two first-degree relatives with confirmed pancreatic cancer that do not fulfill the criteria of other inherited cancer syndromes with an increased risk for the development of PC, such as Peutz-Jeghers syndrome, hereditary pancreatitis and hereditary breast and ovarian cancer. FPC is a mostly autosomal dominant inherited tumor syndrome with a heterogeneous phenotype. The major genetic defect has not been identified yet, although mutations, for example in the BRCA2 gene, could be identified in some FPC families. Nevertheless, most experts recommend participation in screening and surveillance programs to high-risk individuals. Most board-approved screening programs are based on endoscopic ultrasound. The first data on the prospective screening of high-risk individuals have demonstrated that precursor lesions of PC can be identified, but false-positive findings do occur.

German national case collection for familial pancreatic cancer (FaPaCa): ten years experience

Familial pancreatic cancer (FPC) is a rare hereditary tumor syndrome. The 10-years experience of the national case collection for familial pancreatic cancer of Germany (FaPaCa) is reported. Since 1999 FaPaCa has collected families with at least two first-degree relatives with confirmed pancreatic cancer (PC), who did not fulfill the criteria of other hereditary tumor syndromes. Histopathological verification of tumor diagnoses, and genetic counseling were prerequisites for enrollment of families in FaPaCa. 94 of 452 evaluated families fulfilled the criteria for partaking in FaPaCa. PC represented the sole tumor entity in 38 (40%) families. In 56 families additional tumor types occurred, including breast cancer (n = 28), colon cancer (n = 20) and lung cancer (n = 11). In 70 (74%) families the pattern of inheritance was consistent with an autosomal dominant trait. Compared to the preceding generation, a younger age of onset was observed in the offspring of PC patients (median: 57 vs. 69 years), indicating anticipation. Mutation analyses of BRCA2, PALB2, CDKN2a, RNASEL, STK11, NOD2, CHEK2 and PALLD, revealed deleterious causative germline mutations of BRCA2 and PALB2 in 2 of 70 (3%) and 2 of 41 (4.9%) German FPC families, respectively. Prospective PC screening with EUS, MRI and MRCP detected precancerous lesions (IPMN, multifocal PanIN2/3) or carcinoma in 5.5% (4 of 72) to 12.5% (9 of 72) of individuals at risk, depending on histological verification. Appropriate inclusion of families at high risk for PC in registries, such as FaPaCa, provides a unique and excellent tool to gain clinical and genetic knowledge of FPC. Focused research projects can be conducted most efficiently, when data of different FPC registries are combined.

German national case collection for familial pancreatic cancer (FaPaCa): ten years experience

Familial pancreatic cancer (FPC) is a rare hereditary tumor syndrome. The 10-years experience of the national case collection for familial pancreatic cancer of Germany (FaPaCa) is reported. Since 1999 FaPaCa has collected families with at least two first-degree relatives with confirmed pancreatic cancer (PC), who did not fulfill the criteria of other hereditary tumor syndromes. Histopathological verification of tumor diagnoses, and genetic counseling were prerequisites for enrollment of families in FaPaCa. 94 of 452 evaluated families fulfilled the criteria for partaking in FaPaCa. PC represented the sole tumor entity in 38 (40%) families. In 56 families additional tumor types occurred, including breast cancer (n = 28), colon cancer (n = 20) and lung cancer (n = 11). In 70 (74%) families the pattern of inheritance was consistent with an autosomal dominant trait. Compared to the preceding generation, a younger age of onset was observed in the offspring of PC patients (median: 57 vs. 69 years), indicating anticipation. Mutation analyses of BRCA2, PALB2, CDKN2a, RNASEL, STK11, NOD2, CHEK2 and PALLD, revealed deleterious causative germline mutations of BRCA2 and PALB2 in 2 of 70 (3%) and 2 of 41 (4.9%) German FPC families, respectively. Prospective PC screening with EUS, MRI and MRCP detected precancerous lesions (IPMN, multifocal PanIN2/3) or carcinoma in 5.5% (4 of 72) to 12.5% (9 of 72) of individuals at risk, depending on histological verification. Appropriate inclusion of families at high risk for PC in registries, such as FaPaCa, provides a unique and excellent tool to gain clinical and genetic knowledge of FPC. Focused research projects can be conducted most efficiently, when data of different FPC registries are combined.

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.

New insights into the role of RNase L in innate immunity

The interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase (OAS)/RNase L pathway blocks infections by some types of viruses through cleavage of viral and cellular single-stranded RNA. Viruses induce type I IFNs that initiate signaling to the OAS genes. OAS proteins are pathogen recognition receptors for the viral pathogen-associated molecular pattern, double-stranded RNA. Double-stranded RNA activates OAS to produce p(x)5'A(2'p5'A)(n); x = 1-3; n > 2 (2-5A) from ATP. Upon binding 2-5A, RNase L is converted from an inactive monomer to a potently active dimeric endoribonuclease for single-stranded RNA. RNase L contains, from N- to C-terminus, a series of 9 ankyrin repeats, a linker, several protein kinase-like motifs, and a ribonuclease domain homologous to Ire1 (involved in the unfolded protein response). In the past few years, it has become increasingly apparent that RNase L and OAS contribute to innate immunity in many ways. For example, small RNA cleavage products produced by RNase L during viral infections can signal to the retinoic acid-inducible-I like receptors to amplify and perpetuate signaling to the IFN-β gene. In addition, RNase L is now implicated in protecting the central nervous system against viral-induced demyelination. A role in tumor suppression was inferred by mapping of the RNase L gene to the hereditary prostate cancer 1 (HPC1) gene, which in turn led to discovery of the xenotropic murine leukemia-related virus. A broader role in innate immunity is suggested by involvement of RNase L in cytokine induction and endosomal pathways that suppress bacterial infections. These newly described findings about RNase L could eventually provide the basis for developing broad-spectrum antimicrobial drugs.

Prevalence of BRCA2 and CDKN2a mutations in German familial pancreatic cancer families

Previous small scale studies reported that deleterious BRCA2 and CDKN2a germline mutations contribute to a subset of families with inherited pancreatic cancer. As the prevalence of those mutations in the setting of familial pancreatic cancer is still not well defined for the German population, we evaluated the presence of BRCA2 and CDKN2a germline mutations in a large cohort of familial pancreatic cancer (FPC) families from the German National Case Collection for Familial Pancreatic Cancer (FaPaCa). Fifty-six FPC families with at least two-first-degree relatives with confirmed pancreatic cancer that did not fulfill the criteria of other tumor predisposition syndromes, were analyzed for BRCA2 and CDKN2a germline mutations by DHPLC and/or direct sequencing. No deleterious CDKN2a mutations were identified in our families suggesting that CDKN2a mutations are unlikely to predispose PC in FPC families without melanoma. No deleterious BRCA2 mutations, but 6 unclassified variants, were detected in our FPC collection. Combining the prevalence of deleterious BRCA2 germline mutations from our previous separate study with the data from this study we were able to much more accurately estimate the BRCA2 carrier frequency for FPC families in the German population. A total of two mutations and 6 unclassified variants (mutation range: 2.8-11.4%) were thus identified in 70 German FPC families, indicating that the prevalence of BRCA2 mutations in the German FPC population is less frequent than previously reported.

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.

Identification of cellular genes induced in human cells after activation of the OAS/RNaseL pathway by vaccinia virus recombinants expressing these antiviral enzymes

Interferon (IFN) type I induces the expression of antiviral proteins such as 2',5'-oligoadenylate synthetases (OAS). The enzyme OAS is activated by dsRNA to produce 5'-phosphorylated, 2-5-linked oligoadenylates (2-5A) that activate RNaseL which, in turn, triggers RNA breakdown, leading to multiple biological functions. Although RNaseL is required for IFN antiviral function, there are many aspects of the molecular mechanisms that remain obscure. Here, we have used microarray analyses from human HeLa cells infected with vaccinia virus (VACV) recombinants expressing OAS-RNaseL enzymes (referred as 2-5A system) with the aim to identify host genes that are up- or down-regulated in the course of infection by the activation of this antiviral pathway. We found that activation of the 2-5A system from VACV recombinants produces a remarkable stimulation of transcription for genes that regulate many cellular processes, like those that promote cell growth arrest, GADD45B and KCTD11, apoptosis as CUL2, PDCD6, and TNFAIP8L2, IFN-stimulated genes as IFI6, and related to tumor suppression as PLA2G2A. The 2-5A system activation produces down-regulation of transcription of some genes that promote cell growth as RUNX2 and ESR2 and of genes in charge to maintain mitochondria homeostasis as MIPEP and COX5A. These results reveal new genes induced in response to the activation of the 2-5A system with roles in apoptosis, translational control, cell growth arrest, and tumor suppression.

The role of mammalian ribonucleases (RNases) in cancer

Ribonucleases (RNases) are a group of enzymes that cleave RNAs at phosphodiester bonds resulting in remarkably diverse biological consequences. This review focuses on mammalian RNases that are capable of, or potentially capable of, cleaving messenger RNA (mRNA) as well as other RNAs in cells and play roles in the development of human cancers. The aims of this review are to provide an overview of the roles of currently known mammalian RNases, and the evidence that associate them as regulators of tumor development. The roles of these RNases as oncoproteins and/or tumor suppressors in influencing cell growth, apoptosis, angiogenesis, and other cellular hallmarks of cancer will be presented and discussed. The RNases under discussion include RNases from the conventional mRNA decay pathways, RNases that are activated under cellular stress, RNases from the miRNA pathway, and RNases with multifunctional activity.

The inherited genetic component of sporadic pancreatic adenocarcinoma

Pancreatic cancer, like many other complex diseases, has genetic and environmental components to its etiology. It is likely that relatively common genetic variants with modest effects on pancreatic cancer risk play an important role in both familial and sporadic forms of the disease, either individually or in interaction with environmental factors. The relatively high frequency of such variants means that they could potentially explain a substantial portion of disease risk. Here we summarize the findings published to date from genetic association studies. In general, very few low-penetrance variants have been identified and those that have require replication in independent studies. Possible gene-environment interactions arising from these studies also require replication. More comprehensive approaches are needed to make progress, including global analyses of biologically sound pathways and genome-wide association studies. Large sample sizes are required to do this appropriately and multi-study consortia make this possible. A number of consortia of pre-existing studies have already been formed, and these will facilitate the identification of further low-penetrance variants and gene-environment interaction. However, these approaches do not substitute for the design of novel, sufficiently powered studies that apply uniform criteria to case selection, the acquisition of environmental exposure information, and to biological sample collection.

[RNase L, a crucial mediator of innate immunity and other cell functions]

The 2-5A/RNase L pathway is one of the first cellular defences against viruses. RNase L is an unusual endoribonuclease which activity is strictly regulated by its binding to a small oligonucleotide, 2-5A. 2-5A itself is very unusual, consisting of a series of 5'- triphosphorylated oligoadenylates with 2'-5' bonds. But RNase L activity is not limited to viral RNA cleavage. RNase L plays a central role in innate immunity, apoptosis, cell growth and differentiation by regulating cellular RNA stability and expression. Default in its activity leads to increased susceptibility to virus infections and to tumor development. RNase L gene has been identified as HPC1 (Hereditary Prostate Cancer 1) gene. Study of RNase L variant R462Q in etiology of prostate cancer has led to the identification of the novel human retrovirus closely related to xenotropic murine leukemia viruses (MuLVs) and named XMRV.

Caffeic acid phenethyl ester induces apoptosis of human pancreatic cancer cells involving caspase and mitochondrial dysfunction

AIMS

This study aimed to investigate the effect of caffeic acid phenethyl ester (CAPE), an active component isolated from honeybee propolis, in inducing apoptosis in human pancreatic cancer cells.

METHODS

Inhibition of viability of BxPC-3 and PANC-1 cell lines induced by CAPE was estimated by a trypan blue dye exclusion test. The type of cell death in BxPC-3 after CAPE treatment was characterized by observation of morphology, sub-G1 DNA content, annexin-V/PI staining, caspase-3 and caspase-7 assay, and DNA agarose gel electrophoresis.

RESULTS

CAPE (10 microg/ml) resulted in marked inhibition of viability of BxPC-3 (80.4 +/- 4.1%) and PANC-1 (74.3 +/- 2.9%) cells. CAPE induced a time-dependent increase in hypodiploid percentage and a significant decrease in mitochondrial transmembrane potential in BxPC-3 cells. It induced morphological changes of typical apoptosis, but no DNA fragmentation was noted by DNA electrophoresis. The inhibition of growth and increased in the proportion of sub-G(1) cells was partially blocked by pretreatment with the pan-caspase inhibitor Z-VAD-fmk (50 microM) in BxPC-3 cells indicating a caspase-related mechanism in CAPE-induced apoptosis. Caspase-3/caspase-7 activity was approximately 2 times greater in CAPE-treated BxPC-3 cells compared with control cells.

CONCLUSIONS

These results suggest that CAPE is a potent apoptosis-inducing agent. Its action is accompanied by mitochondrial dysfunction and activation of caspase-3/caspase-7.

[Hereditary pancreatic cancer]

An inherited predisposition to pancreatic cancer (PC) is prevalent in about 3% of PC cases and is currently believed to occur in three distinct clinical settings, (1) hereditary tumour predisposition syndromes with an increased risk of PC such as Peutz-Jeghers syndrome and familial atypical multiple mole melanoma, (2) hereditary pancreatitis and cystic fibrosis, in which genetically determined early-age changes of the pancreas can predispose to the development of PC, and (3) familial pancreatic cancer syndrome (FPC). According to a recent consensus conference, high-risk individuals from PC-prone families should be enrolled in board-approved, prospective, controlled screening programs at expert centres. Based on the available data, prophylactic pancreatectomy is not indicated, since the underlying causative gene defect of the FPC syndrome is still unknown and the penetrance of PC in other tumour predisposition syndromes is either low or yet undetermined. In case of the diagnosis of a PC or high-grade precursor lesions, a prophylactic extension of the resection can be considered, since patients with hereditary PC often develop multifocal pancreatic lesions.

Variants in inflammation genes and the risk of biliary tract cancers and stones: a population-based study in China

To evaluate the role of chronic inflammation in the development of gallstones and biliary tract cancer, we examined the risk associated with 62 single nucleotide polymorphisms (SNPs), in 22 inflammation-related genes, in a population-based case-control study conducted in Shanghai, China, where the incidence of biliary tract cancer has been increasing in recent decades. The study included 411 cases with biliary tract cancer (237 gallbladder, 127 extrahepatic bile duct, and 47 ampulla of Vater), 895 with biliary stones, and 786 controls randomly selected from the population. Unconditional logistic regression was used to calculate odds ratios and 95% confidence intervals for the association of individual SNPs and haplotypes with biliary stones and biliary tract cancer. Of the 62 SNPs examined, 14 were related to the risk of biliary cancer and stones. Specifically, variants in the IL8, IL8RB, RNASEL, and NOS2 genes were associated with biliary stones, whereas VEGF variants were associated with gallbladder cancer. Of the 10 genes with multiple SNPs from which we inferred haplotypes, only one IL8RB haplotype, consisting of 3 SNPs (rs2230054, rs1126579, and rs1126580), was associated with the risk of bile duct cancer (P = 0.003) and biliary stones (P = 0.02), relative to the most frequent haplotype. In summary, common variants in genes that influence inflammatory responses may predispose to gallstones and biliary tract cancer, suggesting the need for future studies into the immunologic and inflammatory pathways that contribute to biliary diseases, including cancer.

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.

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.

Diverse functions of RNase L and implications in pathology

The endoribonuclease L (RNase L) is the effector of the 2-5A system, a major enzymatic pathway involved in the molecular mechanism of interferons (IFNs). RNase L is a very unusual nuclease with a complex mechanism of regulation. It is a latent enzyme, expressed in nearly every mammalian cell type. Its activation requires its binding to a small oligonucleotide, 2-5A. 2-5A is a series of unique 5'-triphosphorylated oligoadenylates with 2'-5' phosphodiester bonds. By regulating viral and cellular RNA expression, RNase L plays an important role in the antiviral and antiproliferative activities of IFN and contributes to innate immunity and cell metabolism. The 2-5A/RNase L pathway is implicated in mediating apoptosis in response to viral infections and to several types of external stimuli. Several recent studies have suggested that RNase L could have a role in cancer biology and evidence of a tumor suppressor function of RNase L has emerged from studies on the genetics of hereditary prostate cancer.

Low frequency of CHEK2 mutations in familial pancreatic cancer

Familial pancreatic cancer (FPC) is a rare tumour syndrome and its underlying major gene defect is still unknown. Recently, CHEK2 has been identified as multi-organ cancer susceptibility gene associated with a predisposition to breast, prostate and colon cancer. Since these cancers also are associated with some FPC families, we have analysed 35 index patients of German FPC families for CHEK2 mutations. The CHEK2 * 1100delC mutation was found in 1 (3%) of 35 FPC families. Given the low expected mutation rate of up to 1.4% for CHEK2 * 1100delC in the European population our data are suggestive for possible contribution of CHEK2 mutations to a small subset of FPC.

Low Frequency of CHEK2 Mutations in Familial Pancreatic Cancer

Familial pancreatic cancer (FPC) is a rare tumour syndrome and its underlying major gene defect is still unknown. Recently, CHEK2 has been identified as multi-organ cancer susceptibility gene associated with a predisposition to breast, prostate and colon cancer. Since these cancers also are associated with some FPC families, we have analysed 35 index patients of German FPC families for CHEK2 mutations. The CHEK2 * 1100delC mutation was found in 1 (3%) of 35 FPC families. Given the low expected mutation rate of up to 1.4% for CHEK2 * 1100delC in the European population our data are suggestive for possible contribution of CHEK2 mutations to a small subset of FPC.

Familial pancreatic cancer syndromes

Hereditary pancreatic cancer (PC) is rare and extremely heterogeneous, and it accounts for approximately 2% of all PC cases. The major component of hereditary PC is the familial pancreatic cancer syndrome. Although up to 20% of hereditary PC cases are associated with germline mutations in the BRCA2, CDKN2A, PRSS1,STKI1, or MMR genes, the major underlying gene defect(s) is still unknown. Although hereditary PC is rare, the data on PC families that have been collected by various study groups worldwide provide a unique opportunity to evaluate the natural history, causative gene alterations, new diagnosis and chemoprevention strategies as well as treatment modalities.