JC virus DNA is present in the mucosa of the human colon and in colorectal cancers

The Impact of the Gut Microbiome, Environment, and Diet in Early-Onset Colorectal Cancer Development

Traditionally considered a disease common in the older population, colorectal cancer is increasing in incidence among younger demographics. Evidence suggests that populational- and generational-level shifts in the composition of the human gut microbiome may be tied to the recent trends in gastrointestinal carcinogenesis. This review provides an overview of current research and putative mechanisms behind the rising incidence of colorectal cancer in the younger population, with insight into future interventions that may prevent or reverse the rate of early-onset colorectal carcinoma.

How Can the Microbiome Induce Carcinogenesis and Modulate Drug Resistance in Cancer Therapy?

Over the years, cancer has been affecting the lives of many people globally and it has become one of the most studied diseases. Despite the efforts to understand the cell mechanisms behind this complex disease, not every patient seems to respond to targeted therapies or immunotherapies. Drug resistance in cancer is one of the limiting factors contributing to unsuccessful therapies; therefore, understanding how cancer cells acquire this resistance is essential to help cure individuals affected by cancer. Recently, the altered microbiome was observed to be an important hallmark of cancer and therefore it represents a promising topic of cancer research. Our review aims to provide a global perspective of some cancer hallmarks, for instance how genetic and epigenetic modifications may be caused by an altered human microbiome. We also provide information on how an altered human microbiome can lead to cancer development as well as how the microbiome can influence drug resistance and ultimately targeted therapies. This may be useful to develop alternatives for cancer treatment, i.e., future personalized medicine that can help in cases where traditional cancer treatment is unsuccessful.

JC Polyomavirus T-antigen protein expression and the risk of colorectal cancer: Systematic review and meta-analysis of case-control studies

JC Polyomavirus (JCV) is a human polyomavirus encoding T-antigen protein, which is implicated in carcinogenesis. JCV is prevalent in the upper and lower gastrointestinal track. Several studies have reported JCV associations with the risk of developing colorectal cancer (CRC), however, these findings remain controversial. Since JCV DNA may be present in healthy tissues as well as transformed tissues, JCV T-antigen expression could be a more useful measure of JCV's association with cancer development. The aim of this study is to conduct a meta-analysis of case-control studies to investigate if there is a significant association between JCV T-antigen protein expression and risk of CRC. A systematic review was performed to identify studies reporting JCV DNA prevalence in CRC and JCV T-antigen expression. The strength of the association was estimated by odds ratios (ORs). Five (of 66) studies satisfied analysis inclusion criteria, and spanned years 1999 to 2022. Random effects meta-analysis of CRC cases versus controls showed an 11-fold increased risk of CRC development in JCV DNA positive samples with JCV T-antigen expression versus normal tissues (OR 10.95; 95% CI: 2.48-48.24; P = 0.0016). The results of this meta-analysis of JCV infection followed by JCV T-antigen protein expression for the risk of CRC support the argument that JCV infection significantly increases the risk of colorectal cancer in tissues where the JCV T-antigen protein is expressed. Further research with JCV T-antigen expression in relation to CRC development is needed.

Unusually high incidence of polyomavirus JC infection in the higher grade of colorectal cancer tissues in Taiwan

Introduction

The human JC polyomavirus (JCPyV) has been detected in colorectal cancer (CRC) tissues and is suggested to contribute to CRC tumorigenesis. The rearrangement of the JCPyV regulatory region is supposedly associated with CRC development. The progression of CRC involves the stepwise accumulation of mutations. The large tumor antigen (LT) of JCPyV can trigger uncontrolled cell cycle progression by targeting oncogenes, and tumor suppressor genes, and causing chromosome instability. Few studies have focused on the presence of JCPyV DNA in the higher grade of CRC tissues.

Methods

We collected 95 tissue blocks from samples of stages I, II, III, and IV CRC. Nested PCR targeting the regulatory region of the viral genome was performed to determine the presence of JCPyV DNA in the various stages of colorectal cancer tissues.

Results

The nested PCR results showed that the positive rate of JCPyV DNA increased with the progression of CRC stages. The archetypal-like, non-rearrangement genotype of JCPyV with subtle mutations was the major genotype found in CRC samples.

Conclusions

This finding in our study suggests that there may be an association between JCPyV and CRC progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00756-2.

Virus-host interaction network analysis in Colorectal cancer identifies core virus network signature and small molecules

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Systematic analysis of virus-host networks identified key pathways in CRC.

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Core virus-CRC network revealed the growth pathway regulated by viruses.

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Short linear motif analysis identified druggable regions in virus proteins.

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Virtual screening revealed key anti-viral molecules against viral proteins.

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Molecular dynamics simulations showed the effect of anti-viral molecules.

Colorectal cancer (CRC) is a significant contributor to cancer-related deaths caused by an unhealthy lifestyle. Multiple studies reveal that viruses are involved in colorectal tumorigenesis. The viruses such as Human Cytomegalovirus (HCMV), Human papillomaviruses (HPV16 & HPV18), and John Cunningham virus (JCV) are known to cause colorectal cancer. The molecular mechanisms of cancer genesis and maintenance shared by these viruses remain unclear. We analysed the virus-host networks and connected them with colorectal cancer proteome datasets and extracted the core shared interactions in the virus-host CRC network. Our network topology analysis identified prominent virus proteins RL6 (HCMV), VE6 (HPV16 and HPV18), and Large T antigen (JCV). Sequence analysis uncovered short linear motifs (SLiMs) in each viral target. We used these targets to identify the antiviral drugs through a structure-based virtual screening approach. This analysis highlighted that temsavir, pimodivir, famotine, and bictegravir bind to each virus protein target, respectively. We also assessed the effect of drug binding using molecular dynamic simulations, which shed light on the modulatory effect of drug molecules on SLiM regions in viral targets. Hence, our systematic screening of virus-host networks revealed viral targets, which could be crucial for cancer therapy.

The Roles of the Virome in Cancer

Viral infections as well as changes in the composition of the intestinal microbiota and virome have been linked to cancer. Moreover, the success of cancer immunotherapy with checkpoint inhibitors has been correlated with the intestinal microbial composition of patients. The transfer of feces-which contain mainly bacteria and their viruses (phages)-from immunotherapy responders to non-responders, known as fecal microbiota transplantation (FMT), has been shown to be able to convert some non-responders to responders. Since phages may also increase the response to immunotherapy, for example by inducing T cells cross-reacting with cancer antigens, modulating phage populations may provide a new avenue to improve immunotherapy responsiveness. In this review, we summarize the current knowledge on the human virome and its links to cancer, and discuss the potential utility of bacteriophages in increasing the responder rate for cancer immunotherapy.

Higher detection of JC polyomavirus in colorectal cancerous tissue after pretreatment with topoisomerase I enzyme; colorectal tissue serves as a JCPyV persistence site

BACKGROUND

The JC polyomavirus has been blamed to contribute in colorectal cancer (CRC), however, the topic is still controversial. Varying detection rate of JCPyV genome has been reported mainly due to technical reasons. Here, we provide summative data on the topic, with emphasize on technical issues.

METHODS

Formalin-fixed paraffin-embedded tissue samples from 50 patients with CRC, consisting of tumoral and non-cancerous marginal tissue (totally 100 samples) were included in the study. After DNA extraction, specific JCPyV T-Ag sequences were targeted using Real-time PCR. To unwind the supercoiled JCPyV genome, pretreatment with topoisomerase I, was applied. Immunohistochemical (IHC) staining was performed using an anti-T-Ag monoclonal antibody.

RESULTS

In the first attempts, no samples were found to be positive in Real-time PCR assays. However, JCPyV sequences were found in 60% of CRC tissues and 38% of non-cancerous colorectal mucosa after application of pre-treatment step with topoisomerase I enzyme (P = 0.028). T-Ag protein was found in the nuclear compartment of the stained cells in IHC assays.

CONCLUSIONS

The presence of JCPyV in CRC tissues, as well as T-Ag localization in the nucleolus, where its oncogenic effect takes place, may provide supporting evidence for JCPyV involvement in CRC development. The study highlights the importance of using topoisomerase I to enhance JCPyV genome detection. Also, colorectal tissue is one of the permissive human tissue for JC resistance after preliminary infection.

Viruses in colorectal cancer

Increasing evidence suggests that microorganisms might represent at least highly interesting cofactors in colorectal cancer (CRC) oncogenesis and progression. Still, associated mechanisms, specifically in colonocytes and their microenvironmental interactions, are still poorly understood. Although, currently, at least seven viruses are being recognized as human carcinogens, only three of these – Epstein–Barr virus (EBV), human papillomavirus (HPV) and John Cunningham virus (JCV) – have been described, with varying levels of evidence, in CRC. In addition, cytomegalovirus (CMV) has been associated with CRC in some publications, albeit not being a fully acknowledged oncovirus. Moreover, recent microbiome studies set increasing grounds for new hypotheses on bacteriophages as interesting additional modulators in CRC carcinogenesis and progression. The present Review summarizes how particular groups of viruses, including bacteriophages, affect cells and the cellular and microbial microenvironment, thereby putatively contributing to foster CRC. This could be achieved, for example, by promoting several processes – such as DNA damage, chromosomal instability, or molecular aspects of cell proliferation, CRC progression and metastasis – not necessarily by direct infection of epithelial cells only, but also by interaction with the microenvironment of infected cells. In this context, there are striking common features of EBV, CMV, HPV and JCV that are able to promote oncogenesis, in terms of establishing latent infections and affecting p53‐/pRb‐driven, epithelial–mesenchymal transition (EMT)‐/EGFR‐associated and especially Wnt/β‐catenin‐driven pathways. We speculate that, at least in part, such viral impacts on particular pathways might be reflected in lasting (e.g. mutational or further genomic) fingerprints of viruses in cells. Also, the complex interplay between several species within the intestinal microbiome, involving a direct or indirect impact on colorectal and microenvironmental cells but also between, for example, phages and bacterial and viral pathogens, and further novel species certainly might, in part, explain ongoing difficulties to establish unequivocal monocausal links between specific viral infections and CRC.

Associations Between Gastric Cancer Risk and Virus Infection Other Than Epstein-Barr Virus: A Systematic Review and Meta-analysis Based on Epidemiological Studies

INTRODUCTION

Besides Helicobacter pylori and Epstein-Barr virus, other viruses might play potential roles in gastric carcinogenesis. This systematic review and meta-analysis was conducted to compare the prevalence of the viruses between gastric cancer (GC) and any controls.

METHODS

Comprehensive literature was searched up to January 25, 2019, and search was updated on April 6, 2020. The studies that compared the prevalence of viruses other than Epstein-Barr virus between GC and healthy or nonmalignant controls were eligible. Stata 12.0 software was used for heterogeneity tests and meta-analyses. Meanwhile, subgroup analysis, sensitivity analysis, and publication bias evaluation were performed where applicable. The power (1-β) was estimated by the PASS 11 software for each individual study.

RESULTS

A total of 41 eligible studies were included, concerning 11 kinds of viruses. Prevalence were significantly higher in GC for hepatitis B virus (odds ratio [OR] = 1.39, 95% confidence interval [CI] 1.11-1.75), human cytomegalovirus (OR = 2.25, 95% CI 1.14-4.43), human papillomavirus (HPV) (OR = 1.63, 95% CI 1.05-2.54), and John Cunningham virus (OR = 2.52, 95% CI 1.26-5.04). In subgroup analyses, HPV-16 infection was significantly associated with GC (OR = 2.42, 95% CI 1.00-5.83).

DISCUSSION

This study demonstrated that hepatitis B virus, human cytomegalovirus, HPV, and John Cunningham virus were more prevalent in GC. However, the causal relationship between their infection and risk of GC remains inconclusive, and further investigations are required.

JC Polyomavirus and Transplantation: Implications for Virus Reactivation after Immunosuppression in Transplant Patients and the Occurrence of PML Disease

The JC polyomavirus (JCPyV/JCV) is a member of the Polyomaviridae family and is ubiquitious in the general population, infecting 50–80% of individuals globally. A primary infection with JCV usally results in an asymptomatic, persistent infection that establishes latency in the renourinary tract. Reactivation from latency via iatrogenic immununosuppression for allograft transplantation may result in organ pathology and a potential life-threatening neuropathological disease in the form of progressive multifocal leukoencephalopathy (PML). Currently, no treatment exists for PML, a rare complication that occurs after transplantation, with an incidence of 1.24 per 1000 persons a year among solid organ transplant patients. PML is also observed in HIV patients who are immununosuppressed and are not receiving antiretroviral therapy, as well as individuals treated with biologics to suppress chronic inflammatory responses due to multiple sclerosis, Crohn’s disease, non-Hodgkin’s lymphoma, rheumatoid arthritis, and other autoimmune-mediated hematological disorders. Here, we describe the proposed mechanisms of JCV reactivation as it relates to iatrogenic immunosuppression for graft survival and the treatment of proinflammatory disease, such as biologics, proposed trafficking of JCV from the renourinary tract, JCV central nervous system dissemination and the pathology of PML in immunosuppressed patients, and potential novel therapeutics for PML disease.

Induction of Brain Tumors by the Archetype Strain of Human Neurotropic JCPyV in a Transgenic Mouse Model

JC Virus (JCPyV), a member of the Polyomaviridiæ family, is a human neurotropic virus with world-wide distribution. JCPyV is the established opportunistic infectious agent of progressive multifocal leukoencephalopathy, a fatal demyelinating disease, which results from the cytolytic infection of oligodendrocytes. Mutations in the regulatory region of JCPyV determine the different viral strains. Mad-1 the strain associated with PML contains two 98 base pair repeats, whereas the archetype strain (CY), which is the transmissible form of JCPyV, contains only one 98 tandem with two insertions of 62 and 23 base pairs respectively. The oncogenicity of JCPyV has been suspected since direct inoculation into the brain of rodents and primates resulted in the development of brain tumors and has been attributed to the viral protein, T-Antigen. To further understand the oncogenicity of JCPyV, a transgenic mouse colony containing the early region of the archetype strain (CY), under the regulation of its own promoter was generated. These transgenic animals developed tumors of neural crest origin, including: primitive neuroectodermal tumors, medulloblastomas, adrenal neuroblastomas, pituitary tumors, malignant peripheral nerve sheath tumors, and glioblastomas. Neoplastic cells from all different phenotypes express T-Antigen. The close parallels between the tumors developed by these transgenic animals and human CNS tumors make this animal model an excellent tool for the study of viral oncogenesis.

The Viral Janus: Viruses as Aetiological Agents and Treatment Options in Colorectal Cancer

In recent years, our understanding of the importance of microorganisms on and within our bodies has been revolutionized by the ability to characterize entire microbial communities. No more so is this true than in cases of disease. Community studies have revealed strong associations between microbial populations and disease states where such concomitance was previously absent from aetiology: including in cancers. The study of viruses, in particular, has benefited from the development of new community profiling techniques and we are now realising that their prominence within our physiology is nearly as broad as the diversity of the organisms themselves. Here, we examine the relationship between viruses and colorectal cancer (CRC), the leading cause of gastrointestinal cancer-related death worldwide. In CRC, viruses have been suggested to be involved in oncogenesis both directly, through infection of our cells, and indirectly, through modulating the composition of bacterial communities. Interestingly though, these characteristics have also led to their examination from another perspective—as options for treatment. Advances in our understanding of molecular and viral biology have caused many to look at viruses as potential modular biotherapeutics, where deleterious characteristics can be tamed and desirable characteristics exploited. In this article, we will explore both of these perspectives, covering how viral infections and involvement in microbiome dynamics may contribute to CRC, and examine ways in which viruses themselves could be harnessed to treat the very condition their contemporaries may have had a hand in creating.

Viruses in Cancers of the Digestive System: Active Contributors or Idle Bystanders?

The human virome, which is a collection of all the viruses that are present in the human body, is increasingly being recognized as an essential part of the human microbiota. The human gastrointestinal tract and related organs (e.g., liver, pancreas, and gallbladder)-composing the gastrointestinal (or digestive) system-contain a huge number of viral particles which contribute to maintaining tissue homeostasis and keeping our body healthy. However, perturbations of the virome steady-state may, both directly and indirectly, ignite/sustain oncogenic mechanisms contributing to the initiation of a dysplastic process and/or cancer progression. In this review, we summarize and discuss the available evidence on the association and role of viruses in the development of cancers of the digestive system.

A Comprehensive Proteomics Analysis of the JC Virus (JCV) Large and Small Tumor Antigen Interacting Proteins: Large T Primarily Targets the Host Protein Complexes with V-ATPase and Ubiquitin Ligase Activities While Small t Mostly Associates with Those Having Phosphatase and Chromatin-Remodeling Functions

The oncogenic potential of both the polyomavirus large (LT-Ag) and small (Sm t-Ag) tumor antigens has been previously demonstrated in both tissue culture and animal models. Even the contribution of the MCPyV tumor antigens to the development of an aggressive human skin cancer, Merkel cell carcinoma, has been recently established. To date, the known primary targets of these tumor antigens include several tumor suppressors such as pRb, p53, and PP2A. However, a comprehensive list of the host proteins targeted by these proteins remains largely unknown. Here, we report the first interactome of JCV LT-Ag and Sm t-Ag by employing two independent “affinity purification/mass spectroscopy” (AP/MS) assays. The proteomics data identified novel targets for both tumor antigens while confirming some of the previously reported interactions. LT-Ag was found to primarily target the protein complexes with ATPase (v-ATPase and Smc5/6 complex), phosphatase (PP4 and PP1), and ligase (E3-ubiquitin) activities. In contrast, the major targets of Sm t-Ag were identified as Smarca1/6, AIFM1, SdhA/B, PP2A, and p53. The interactions between “LT-Ag and SdhB”, “Sm t-Ag and Smarca5”, and “Sm t-Ag and SDH” were further validated by biochemical assays. Interestingly, perturbations in some of the LT-Ag and Sm t-Ag targets identified in this study were previously shown to be associated with oncogenesis, suggesting new roles for both tumor antigens in novel oncogenic pathways. This comprehensive data establishes new foundations to further unravel the new roles for JCV tumor antigens in oncogenesis and the viral life cycle.

Multiple Signatures of the JC Polyomavirus in Paired Normal and Altered Colorectal Mucosa Indicate a Link with Human Colorectal Cancer, but Not with Cancer Progression

The JC polyomavirus (JCV) has been repeatedly but discordantly detected in healthy colonic mucosa, adenomatous polyps, and colorectal cancer (CRC), and proposed to contribute to oncogenesis. The controversies may derive from differences in JCV targets, patient’s cohorts, and methods. Studies of simultaneous detection, quantification, and characterization of JCV presence/expression in paired samples of normal/altered tissues of the same patient are lacking. Therefore, we simultaneously quantified JCV presence (DNA) and expression (mRNA and protein) of T-antigen (T-Ag), Viral Protein 1 (Vp1), and miR-J1-5p in paired normal/altered tissues of CRC or polyps, and from controls. JCV signatures were found in most samples. They increased in patients, but were higher in normal mucosa than in corresponding polyp or CRC lesions. JCV non-coding control region (NCCR) DNA rearrangements increased in CRC patients, also in normal mucosa, thus before the onset of the lesion. A new ∆98bp NCCR DNA rearrangement was detected. T-Ag levels were higher in normal mucosa than in adenoma and adenocarcinoma lesions, but decreased to levels of controls in established CRC lesions. In CRC, miR-J1-5p expression decreased with CRC progression. Vp1 expression was not detected. The data indicate a JCV link with the disease, but possible JCV contributes to oncogenesis should occur at pre-polyp stages.

Association between JC virus and colorectal cancer: systematic review and meta-analysis

Objective: Given the probable role of JC virus in associate with increasing the odds of colorectal cancer, this study was conducted systematically to evaluate the association between JC virus and colorectal cancer.Materials and methods: Systematic reviews of the articles published prior to January 1, 2019 without time and place limitations were done independently through the PubMed, ISI, EMBASE and Medline main databases. The heterogeneity rate was assessed through I2, Chi2 and Tau2, and the sensitivity analysis and meta-regression were used to investigate the source of heterogeneity among the studies.Results: 24 studies with a sample size of 2576 were finally entered into the meta-analysis. The results showed that the prevalence of JC virus in colorectal cancer tissues was about 43% (95% CI: 29% -58%). The meta-analysis results also showed that the presence of JCV in colorectal tissues increased the odds of colorectal cancer 4.70 times as much (OR Pooled = 4.70; 95% CI: 2.95-7.50). Also, the results of the sub-group analysis indicated that the presence of JC virus, compared with the tissues adjacent to the tumour and the healthy control tissues, increased the odds of colorectal cancer (OR Pooled = 4.50, 95% CI: 2.09-9.65 and OR Pooled = 4.70, 95% CI: 2.95-7.50) respectively.Conclusion: The meta-analysis showed that as an oncogene virus, JC could increase the odds of colorectal cancer, reinforcing the hypothesis on the role of viral factors in the pathogenesis of cancers.

Presence of JC Polyomavirus in Nonneoplastic Inflamed Colon Mucosa and Primary and Metastatic Colorectal Cancer

Background

Despite decades of epidemiologic and histopathologic investigations, the association between JC polyomavirus (JCPyV) infection and colorectal cancer (CRC) remains controversial.

Objective

This study tested the presence of JCPyV sequences and determined the viral load in a series of colorectal samples from Iranian patients. In total, 223 formalin-fixed paraffin-embedded samples from patients diagnosed with primary and metastatic CRC as well as with nonneoplastic inflamed colon mucosa were analyzed by quantitative real-time PCR for the presence of JCPyV large tumor antigen (LT-Ag) sequences.

Results

JCPyV LT-Ag sequences were detected in 18.6% of the CRC tissues and in 15.5% of the nonneoplastic control group. Viral LT-Ag was quantified in 18/100 primary colon adenocarcinomas, 2/10 metastatic adenocarcinomas, and 1/3 primary adenocarcinomas of the rectum. Two JCPyV-positive metastatic tumors presented a negative test result for JCPyV in the corresponding primary tumor. The median JCPyV LT-Ag copy number was 64 × 10^-2 per cell and 14 × 10^-2 per cell in the CRC cases and the nonneoplastic samples, respectively. There was no statistically significant difference between the two study groups regarding median LT-Ag DNA load (p = 0.059). Among the JCPyV-positive samples, the LT-Ag DNA load was higher in 2 metastatic tumors (from a patient with lung metastasis: 232 × 10^-2 copies per cell; from a patient with liver metastasis: 121 × 10^-2 copies per cell).

Conclusions

The detection of JCPyV DNA at low copy numbers (lower than 1 viral copy per cell equivalent) and the absence of viral sequences in the corresponding primary tumors of the JCPyV-positive metastatic samples weaken the hypothesis of an etiological role of JCPyV in primary CRC induction.

Could JC virus be linked to chronic idiopathic intestinal pseudo-obstruction?

JC virus is a member of the Polyomavirus family, infects humans worldwide, and 90% of the population carry antibodies to the virus by adult life. The initial infection is asymptomatic, but it may become persistent. JC virus DNA is frequently present in the upper and lower gastrointestinal tracts of healthy adults. Chronic idiopathic intestinal pseudo-obstruction, one of the most severe gastrointestinal motility disorders, is a condition characterized by a clinical picture mimicking small bowel occlusion with related symptoms and signs in the absence of demonstrable mechanical obstruction. Because of the known neuropathic capability of this virus, and its frequent presence in the gut, it has been proposed that JCV might be detectable in tissues of patients with chronic idiopathic intestinal pseudo-obstruction, and possibly be involved in the pathogenesis of this disease, because the virus may actively infect the enteroglial cells of the myenteric plexuses of the patients with chronic idiopathic intestinal pseudo-obstruction. We report two cases of upper idiopathic intestinal pseudo-obstruction associated with JCV infection.

Gut microbiota in colorectal cancer: mechanisms of action and clinical applications

Colorectal cancer (CRC) accounts for about 10% of all new cancer cases globally. Located at close proximity to the colorectal epithelium, the gut microbiota comprises a large population of microorganisms that interact with host cells to regulate many physiological processes, such as energy harvest, metabolism and immune response. Sequencing studies have revealed microbial compositional and ecological changes in patients with CRC, whereas functional studies in animal models have pinpointed the roles of several bacteria in colorectal carcinogenesis, including Fusobacterium nucleatum and certain strains of Escherichia coli and Bacteroides fragilis. These findings give new opportunities to take advantage of our knowledge on the gut microbiota for clinical applications, such as gut microbiota analysis as screening, prognostic or predictive biomarkers, or modulating microorganisms to prevent cancer, augment therapies and reduce adverse effects of treatment. This Review aims to provide an overview and discussion of the gut microbiota in colorectal neoplasia, including relevant mechanisms in microbiota-related carcinogenesis, the potential of utilizing the microbiota as CRC biomarkers, and the prospect for modulating the microbiota for CRC prevention or treatment. These scientific findings will pave the way to clinically translate the use of gut microbiota for CRC in the near future.

Human Polyomavirus JCPyV and Its Role in Progressive Multifocal Leukoencephalopathy and Oncogenesis

The human neurotropic virus JCPyV, a member of the Polyomaviridiae family, is the opportunistic infectious agent of Progressive Multifocal Leukoencephalopathy (PML), a fatal disease seen in severe immunosuppressive conditions and, during the last decade, in patients undergoing immunotherapy. JCPyV is a ubiquitous pathogen with up to 85% of the adult population word-wide exhibiting antibodies against it. Early experiments demonstrated that direct inoculation of JCPyV into the brain of different species resulted in the development of brain tumors and other neuroectodermal-derived neoplasias. Later, several reports showed the detection of viral sequences in medulloblastomas and glial tumors, as well as expression of the viral protein T-Antigen. Few oncogenic viruses, however, have caused so much controversy regarding their role in the pathogenesis of brain tumors, but the discovery of new Polyomaviruses that cause Merkel cell carcinomas in humans and brain tumors in racoons, in addition to the role of JCPyV in colon cancer and multiple mechanistic studies have shed much needed light on the role of JCPyV in cancer. The pathways affected by the viral protein T-Antigen include cell cycle regulators, like p53 and pRb, and transcription factors that activate pro-proliferative genes, like c-Myc. In addition, infection with JCPyV causes chromosomal damage and T-Antigen inhibits homologous recombination, and activates anti-apoptotic proteins, such as Survivin. Here we review the different aspects of the biology and physiopathology of JCPyV.

The Very Low Frequency of Epstein-Barr JC and BK Viruses DNA in Colorectal Cancer Tissues in Shiraz, Southwest Iran

Viruses including Epstein-Barr virus (EBV), JCV and BKV have been reported to be associated with some cancers. The association of these viruses with colorectal cancers remains controversial. Our objective was to investigate their infections association with adenocarcinoma and adenomatous polyps of the colon. Totally, 210 paraffin-embedded tissue specimens encompassing 70 colorectal adenocarcinoma, 70 colorectal adenomatous and 70 colorectal normal tissues were included. The total DNA was extracted, then qualified samples introduced to polymerase chain reaction (PCR). The EBV, JCV and BKV genome sequences were detected using specific primers by 3 different in-house PCR assays. Out of 210 subjects, 98 cases were female and the rest were male. The mean age of the participants was 52 ± 1.64 years. EBV and JCV DNA was detected just in one (1.42%) out of seventy adenocarcinoma colorectal tissues. All adenomatous polyp and normal colorectal tissues were negative for EBV and JCV DNA sequences. Moreover, all the patients and healthy subjects were negative for BKV DNA sequences. The results suggested that EBV and JCV genomes were not detectable in the colorectal tissue of patients with colorectal cancer in our population. Hence, BKV might not be necessitated for the development of colorectal cancer. The findings merit more investigations.

Molecular survey on Merkel cell polyomavirus in patients with colorectal cancer

Background: Merkel cell polyomavirus (MCV) has been associated with Merkel cell carcinoma (MCC) in humans, and its role in other human cancers is under investigation. The aim of this study was to investigate MCV genome infection in patients with colorectal cancer (CRC).Methods: This retrospective, case-control study used archived formalin-fixed, paraffin-embedded (FFPE) tissue samples from colorectal cancer patients (cases) and matched healthy subjects (controls) diagnosed by an expert pathologist from hospitals affiliated with Iran University of Medical Sciences, Tehran, Iran from 2011 to 2016. After DNA extraction with a QIAamp® DNA FFPE Tissue Kit, real-time polymerase chain reaction (PCR) was used for diagnosis. A positive control was produced by cloning with the Generay Biotechnology system. SPSS v.22 was used for analysis of demographic variables.Results: There were 157 participants included in the study: 66 were cases and 91 were controls. Their mean ages (±SD) were 59.35±14.48 and 57.21±14.66, respectively. The proportion of males was 57.6% in the case group and 57.1% in the control group. None of the samples were positive for MCV expression by real-time PCR assay. Association was detected between males with CRC and tumor location in the rectum and between males with CRC and the mucinous tumor type.Conclusion: None of the tissues from the CRC or non-cancerous control groups were positive for MCV genome infection, although a low viral load, the sample type, or the method of use should not be neglected. Further studies are recommended to obtain more comprehensive results.

DNA methyltransferases in virus-associated cancers

Human tumor viruses are either casually linked or contribute in the development of human cancers. Viruses can stimulate oncogenesis through affecting diverse biological pathways in human cells. Growing data have demonstrated frequent involvement of one of the most characteristic parts of cellular epigenetic machinery, DNA methylation, in the oncogenesis. DNA methylation of cellular genes is catalyzed by DNA methyltransferases (DNMTs) as a key effector enzyme in this process. Dysregulation of DNMTs can cause aberrant gene methylation in promoter of cancer-related genes including tumor suppressor genes, resulting in gene silencing. In this regard, the role of tumor viruses is remarkable. Here, in this review, we used published information to elucidate whether tumor viruses are able to manipulate DNMT regulation, and if so, what are its consequences in the process of oncogenesis. This essay also aims to shed light on which cellular pathways have been engaged by viruses to induce DNMTs.

Detection of JC Polyomavirus tumor antigen in gastric carcinoma: a report from Iran

BACKGROUND AND OBJECTIVES

Factors contributing to development of gastric cancer are still under investigation. The JC Virus (JCV), as an oncogenic virus, has been indicated to play a possible role in gastric carcinogenesis. Theoretically, tumor antigen (T-Ag), the viral transforming protein, is capable of binding and inactivating tumor suppressor proteins p53 and pRb, there by promoting cancer development although such a role in gastric cancer is still controversial and additional data is needed to reach a definite conclusion. The prevalence of the virus varies in different geographic regions, therefore, we aimed to investigate JCV presence in cancerous gastric tissues of Iranian patients.

MATERIALS AND METHODS

Thirty-one paired samples were included in this study (total of 62 samples). T-Ag sequences were investigated using real-time PCR in formalin fixed paraffin embedded (FFPE) tissue samples from the tumor site and relevant adjacent non-cancerous tissues (ANCT). In positive samples, JCV copy number (viral load) was also measured using real-time PCR. To evaluate T-Ag protein expression, immunohistochemistry examination was performed using an anti-T-Ag specific antibody.

RESULTS

JCV sequences were detected in 17 out of 31 gastric cancer tissue samples (54.84%) and in 10 out of 31 of the non-cancerous adjacent gastric mucosa (32.25%) (Odds ratio of 2.4). Viral load in tumoral and adjacent tissue samples was not statistically different (p=0.88). Immunohistochemical study confirmed presence of JC T-Ag in the nuclear compartment.

CONCLUSION

We showed the presence of the JC virus in gastric carcinoma tissue samples in our geographic region. This finding provides supportive data for a possible contribution of JCV in gastric cell transformation to malignancy. However, we highly recommend additional investigations to further explore JC virus and gastric cancer in order to reach a conclusion.

Early onset sporadic colorectal cancer: Worrisome trends and oncogenic features

Early onset colorectal cancers, defined as arising before 50 years of age, are a growing health hazard in western and eastern countries alike. The incidence of colon and rectal cancers in young individuals is projected to increase by as much as 90% and 140%, respectively, by 2030. Although several known cancer risk factors (e.g. smoking, alcohol, dietary habits) have been investigated, there is no single compelling explanation for this epidemiological trend. While some early onset colorectal cancers have been associated with germline mutations in cancer predisposition genes, genetic syndromes are implicated in only a fraction of these cancers (20%) and do not explain the rising incidence. Colorectal neoplasms develop through microsatellite instability or chromosomal instability pathways, with most of the early onset colorectal cancers exhibiting microsatellite stable phenotypes. Genome-wide hypomethylation is a feature of a subgroup of early onset cancers, which appears to be correlated with chromosomal instability and poor prognosis.

A viral map of gastrointestinal cancers

Cancers of the gastrointestinal tract (GIT) are expected to account for approximately 20% of all cancers in 2017. Apart from their high incidence, GIT cancers show high mortality rates, placing these malignancies among the most prominent public health issues of our time. Cancers of the GIT are the result of a complex interplay between host genetic factors and environmental factors and frequently arise in the context of a continued active inflammatory response. Several tumor viruses are able to elicit such chronic inflammatory responses. In fact, several viruses have an impact on GIT tumor initiation and progression, as well as on patients' response to therapy and prognosis, through direct and indirect mechanisms. In this review, we have gathered information on different viruses' rates of infection, viral-driven specific carcinogenesis mechanisms and viral-related impact on the prognosis of cancers of the GIT (specifically in organs that have an interface with the environment - esophagus, stomach, intestines and anus). Overall, while some viral infections show a strong causal relation with specific gastrointestinal cancers, these represent a relatively small fraction of GIT malignancies. Other types of cancer, like Esophageal Squamous Cell Carcinoma, require further studies to confirm the carcinogenic role of some viral agents.

Role of Microbiome in Carcinogenesis Process and Epigenetic Regulation of Colorectal Cancer

Epigenetic changes during the development of colorectal cancer (CRC) play a significant role. Along with factors such as diet, lifestyle, and genetics, oncogenic infection, bacteria alone or whole microbiome, has been associated with this tumor type. How gut microbiome contributes to CRC pathogenesis in the host is not fully understood. Most of the epigenetic studies in CRC have been conducted in populations infected with Helicobacter pylori. In the current review, we summarize how the gut microbiota contributes in colon carcinogenesis and the potential role of epigenetic mechanism in gene regulation. We discuss microbiota-mediated initiation and progression of colon tumorigenesis and have also touched upon the role of microbial metabolites as an initiator or an inhibitor for procarcinogenic or antioncogenic activities. The hypothesis of gut microbiota associated CRC revealed the dynamic and complexity of microbial interaction in initiating the development of CRC. In the multifaceted processes of colonic carcinogenesis, gradual alteration of microbiota along with their microenvironment and the potential oncopathogenic microbes mediated modulation of cancer therapy and other factors involved in microbiome dysbiosis leading to the CRC have also been discussed. This review provides a comprehensive summary of the mechanisms of CRC development, the role of microbiome or single bacterial infection in regulating the processes of carcinogenesis, and the intervention by novel therapeutics. Epigenetic mechanism involved in CRC is also discussed.

Role of viruses in gastrointestinal cancer

Gastrointestinal cancers are a global public health problem, which represent a vast majority of all cancer-caused deaths in both men and women. On the other hand, viral pathogens have been long implicated as etiological factors in the onset of certain human cancers, including gastrointestinal tumors. In this regard, Human Papilloma Virus (HPV), Epstein-Barr Virus (EBV), and John Cunningham Virus (JCV) have been more strongly suggested to be involved in gastrointestinal carcinogenesis; so that, the association of HPV with oropharyngeal and anal cancers and also the association of EBV with gastric cancer have been etiologically confirmed by epidemiological and experimental investigations. Although, the association of other viruses is less evident, but may rely on co-factors for their oncogenic roles. Therefore, to improve the prevention and treatment of these classes of cancer, their association with viral agents as potential risk factors should be investigated with care. In this respect, the present review has focused on the existing literature on the subject of viral involvement in gastrointestinal tumorgenesis, by covering and discussing various gastrointestinal cancers, corresponding viral agents and their oncogenic aspects and then summarizing evidences either supporting or rejecting a causal role of these pathogens in gastrointestinal malignancies.

Review on the role of the human Polyomavirus JC in the development of tumors

Almost one fifth of human cancers worldwide are associated with infectious agents, either bacteria or viruses, and this makes the possible association between infections and tumors a relevant research issue. We focused our attention on the human Polyomavirus JC (JCPyV), that is a small, naked DNA virus, belonging to the Polyomaviridae family. It is the recognized etiological agent of the Progressive Multifocal Leukoencephalopathy (PML), a fatal demyelinating disease, occurring in immunosuppressed individuals.

JCPyV is able to induce cell transformation in vitro when infecting non-permissive cells, that do not support viral replication and JCPyV inoculation into small animal models and non human primates drives to tumor formation. The molecular mechanisms involved in JCPyV oncogenesis have been extensively studied: the main oncogenic viral protein is the large tumor antigen (T-Ag), that is able to bind, among other cellular factors, both Retinoblastoma protein (pRb) and p53 and to dysregulate the cell cycle, but also the early proteins small tumor antigen (t-Ag) and Agnoprotein appear to cooperate in the process of cell transformation.

Consequently, it is not surprising that JCPyV genomic sequences and protein expression have been detected in Central Nervous System (CNS) tumors and colon cancer and an association between this virus and several brain and non CNS-tumors has been proposed. However, the significances of these findings are under debate because there is still insufficient evidence of a casual association between JCPyV and solid cancer development.

In this paper we summarized and critically analyzed the published literature, in order to describe the current knowledge on the possible role of JCPyV in the development of human tumors.

Archetype and Rearranged Non-coding Control Regions in Urothelial Bladder Carcinoma of Immunocompetent Individuals

BACKGROUND

Polyomaviruses (PyVs) are potential transforming viruses. Despite their involvement in human tumours still being debated, there is evidence to suggest a role for PyVs in bladder carcinoma (BC). Therefore, a possible association between PyVs and BC was investigated.

MATERIALS AND METHODS

Urine, blood and fresh bladder tissue specimens were collected from 29 patients with BC. PyV prevalence, non-coding control region (NCCR) organization and genotypic analysis were assessed.

RESULTS

Data showed a significant prevalence of John Cunningham (JC) PyV in BC tissues and in urine with respect to BKPyV, while simian virus 40 was not revealed. A BKPyV rearranged NCCR sequence was isolated, whereas a JCPyV archetypal structure was consistently retained. A prevalence of European genotypes was observed.

CONCLUSION

Our data would suggest a JCPyV involvement in cancer progression and a BKPyV association with BC pathogenesis in immunocompetent patients. However, further work is necessary to better understand the exact role of PyVs in urothelial carcinogenesis.

Differential expression of viral agents in lymphoma tissues of patients with ABC diffuse large B-cell lymphoma from high and low endemic infectious disease regions

Diffuse large B-cell lymphoma (DLBCL), the most common type of non-Hodgkin's lymphoma (NHL) in adults, accounts for approximately 30-40% of newly diagnosed lymphomas worldwide. Environmental factors, such as viruses and bacteria, may contribute to cancer development through chronic inflammation and the integration of oncogenes, and have previously been indicated in cervical cancer, hepatocellular carcinoma, gastric cancer and lymphoproliferative disorders. In the present study, the presence of microbial agents was analyzed in the lymphoma tissue of patients with activated B-cell like (ABC) DLBCL. The present study compared two groups of patients from geographically varied regions that possess a difference in the prevalence of viral and other microbial agents. The patient populations were from Sweden (a low endemic infectious disease region) and Egypt (a high endemic infectious disease region). A differential expression of several viruses in lymphoma tissues was noted when comparing Swedish and Egyptian patients. JC polyomavirus (JCV) was detected in Swedish and Egyptian patients and, uniquely, the complete hepatitis B virus (HBV) genome was detected only in Egyptian lymphoma patients. None of these viruses were detected in control lymph tissues from Sweden or Egypt. In total, 38% of the Egyptian patients were found to have HBV surface antigens (HBsAgs) in their serum; however, HBsAgs were not found in any of the Swedish patients. The percentage of serum HBsAgs in Egyptian patients with ABC DLBCL was significantly increased compared with the general Egyptian population (P<0.05). The present study may support a notion that viral agents, including JCV and HBV, may be involved in the tumorigenesis of DLBCL in regions of high infectious disease.

Polyomavirus infections and its clinical relevance in cancer patients: A Prospective Study

BK and JC polyomaviruses (PyV) have been demonstrated to be associated with the pathogenesis of various human cancers. We aimed to investigate the impact of BK and JC polyomavirus infections on several clinical parameters in different human cancers. A total of 150 cancer patients were included in the study (51 patients with solid tumors, 48 patients with lymphomas and 51 patients with leukemias). Amplification of PyV DNA was performed using a semi-nested version of Polymerase chain reaction targeting the T genomic region of PyV. The polyomavirus load was determined using real-time PCR assay. The clinical data were collected. Polyomavirus DNA could be detected in 84 (56%) of 150 of all cancerous patients. The solid tumors had the lowest proportion of JCV (6 (11.8%) of 51), whereas had the highest proportion of JCV (200copies/μl). JCV was more frequent among NHL patients (30%) and absent in HL patients (0%). During follow-up, PyV positivity decreased significantly (p=0.004) in lymphoma patients (n=28). Although PyV positivity decreased significantly from 39% to 7% in 28 of 48 lymphoma patients after treatment, it significantly persisted in leukemic patients after treatment (from 22% to 38%). JC was more frequent among leukemic patients with leukopenia. The presence of JC polyomavirus was more frequent among leukemic patients without any significant impact on their overall survival.

Human JC virus small tumour antigen inhibits nucleotide excision repair and sensitises cells to DNA-damaging agents

The human JC virus (JCV) is potentially carcinogenic to humans as a Group 2B carcinogen, and it is ubiquitous in human populations. To investigate whether the small tumour (ST) antigen of the JCV contributes to genomic instability, we established cell lines stably expressing the JCV ST and examined its role in DNA repair. Results from host cell reactivation (HCR) assay revealed that the established cell lines exhibited lower nucleotide excision repair (NER) activity than the vector control cells did. The presence of γ-H2AX, a marker of DNA damage, indicated that the established cell line contained more DNA damage foci compared with vector control cells. Furthermore, the results of clonogenic analyses indicated that the JCV ST-expressing cells were more sensitive than the vector control cells to ultraviolet (UV) irradiation and cisplatin treatment. Micronuclei formation assay revealed that the JCV ST-positive cells presented more chromosomal breakages than did the JCV ST-negative cells, particularly after exposure to DNA-damaging agents. The xeroderma pigmentosum Group D protein, a DNA helicase involved in NER, was downregulated in the JCV ST-positive cells in response to UV irradiation. The effect of the protein phosphatase 2A (PP2A) inhibitor okadaic acid on NER was similar to that of the ST, which is a PP2A-binding protein. Therefore, the deactivation of the PP2A might underlie ST-mediated NER inhibition. The results of this study indicate that exposing JCV ST-positive cells to DNA-damaging agents causes genomic instability, which contributes to carcinogenesis. Our data provide further evidence on the association between the JCV ST and human cancer.

Could JC virus provoke metastasis in colon cancer?

AIM: To evaluate the prevalence of John Cunningham virus (JC virus) in a small cohort of patients with colon cancer and to assess its presence in hepatic metastasis.

METHODS: Nineteen consecutive patients with histologically diagnosed colon cancer were included in our study, together with ten subjects affected by histologically and serologically diagnosed hepatitis C virus infection. In the patients included in the colon cancer group, JC virus was searched for in the surgical specimen; in the control group, JC virus was searched for in the hepatic biopsy. The difference in the prevalence of JC virus in the hepatic biopsy between the two groups was assessed through the χ² test.

RESULTS: Four out of 19 patients with colon cancer had a positive polymerase chain reaction (PCR) test for JC virus, and four had liver metastasis. Among the patients with liver metastasis, three out of four had a positive PCR test for JC virus in the surgical specimen and in the liver biopsy; the only patient with liver metastasis with a negative test for JC virus also presented a negative test for JC virus in the surgical specimen. In the control group of patients with hepatitis C infection, none of the ten patients presented JC virus infection in the hepatic biopsy. The difference between the two groups regarding JC virus infection was statistically significant (χ² = 9.55, P = 0.002).

CONCLUSION: JC virus may play a broader role than previously thought, and may be mechanistically involved in the late stages of these tumors.

Activation of c-Myc and Cyclin D1 by JCV T-Antigen and β-catenin in colon cancer

During the last decade, mounting evidence has implicated the human neurotropic virus JC virus in the pathology of colon cancer. However, the mechanisms of JC virus-mediated oncogenesis are still not fully determined. One candidate to mediate these effects is the viral early transcriptional product T-Antigen, which has the ability to inactivate cell cycle regulatory proteins such as p53. In medulloblastomas, T-Antigen has been shown to bind the Wnt signaling pathway protein β-catenin; however, the effects of this interaction on downstream cell cycle regulatory proteins remain unknown. In light of these observations, we investigated the association of T-Antigen and nuclear β-catenin in colon cancer cases and the effects of this complex in the activation of the transcription and cell cycle regulators c-Myc and Cyclin D1 in vitro. Gene amplification demonstrated the presence of viral sequences in 82.4% of cases and we detected expression of T-Antigen in 64.6% of cases by immunohistochemistry. Further, we found that T-Antigen and β-catenin co-localized in the nuclei of tumor cells and we confirmed the physical binding between these two proteins in vitro. The nuclear presence of T-Antigen and β-catenin resulted in the significant enhancement of TCF-dependent promoter activity and activation of the β-catenin downstream targets, c-Myc and Cyclin D1. These observations provide further evidence for a role of JCV T-Antigen in the dysregulation of the Wnt signaling pathway and in the pathogenesis of colon cancer.

Immune response to JC virus T antigen in patients with and without colorectal neoplasia

JC virus (JCV) is a polyomavirus that infects approximately 75% of the population and encodes a T antigen (T-Ag) gene, which is oncogenic and inactivates the p53 and pRb/p107/p130 protein families. Previous work in our lab has identified the presence of T-Ag in colorectal neoplasms. While JCV remains in a latent state for the majority of those infected, we hypothesized that a disturbance in immunological control may permit JCV to reactivate, which may be involved in the development of colorectal neoplasia. Our aim was to determine the cell mediated immune response to JCV T-Ag, and determine if it is altered in patients with colorectal adenomatous polyps (AP) or cancers (CRC). Peripheral blood mononuclear cells (PBMCs) isolated from the blood of patients undergoing colonoscopy or colorectal surgery were stimulated by a peptide library covering the entire T-Ag protein of JCV. Cytokine production and T cell proliferation were evaluated following T-Ag stimulation using Luminex and flow cytometry assays. JCV T-Ag peptides stimulated secretion of IL-2, which induced T cell expansion in all three groups. However, stronger IL-10 and IL-13 production was seen in patients without colorectal neoplasms. IP-10 was produced at very high levels in all groups, but not significantly differently between groups. Most patients exhibited CD4(+) and CD8(+) T cells in response to stimulation by the T-Ag clusters. The combination of IL-2 and IP-10 secretion indicates the presence of T-Ag-specific Th1 cells in all patients, which is higher in patients without carcinoma.

MicroRNA miR-J1-5p as a potential biomarker for JC virus infection in the gastrointestinal tract

Introduction

JC virus (JCV), a human polyomavirus that causes progressive multifocal leukoencephalopathy (PML), has been linked to colorectal cancer (CRC). However, determination of JCV infection and its role in carcinogenesis has been challenging, highlighting the need for better diagnostic strategies for this virus. JCV-specific microRNAs (miRNAs) were identified and shown to negatively regulate oncogenic JCV T-Ag. Herein, we determined the pattern of JCV miRNA expression in clinical specimens from healthy subjects and CRC patients.

Material and Methods

JCV miRNA expression was validated in CRC cell lines transfected with the JCV T-Ag. Results were confirmed using CRC tissues that were expressed T-Ag. Expression of JCV-specific miR-J1-5p was measured in fresh stool samples from healthy volunteers, and samples from fecal occult blood test kits from healthy subject, and patients with colorectal neoplasms.

Results

JCV miR-J1-5p was detected in JCV-transfected, but not vector-transfected, CRC cells, and was stable between cell passages. MiR-J1-5p was present in all six JCV T-Ag+ CRC samples. Surprisingly, JCV miRNA was detectable in all normal tissues, but the expression was much lower in CRC tissues. Similarly, miR-J1-5p expression was present in all fecal samples, but expression was lower in CRCs compared to controls or adenoma patients.

Conclusion

JC virus-specific miR-J1-5p miRNA is a potential biomarker for viral infection, and the lower expression in patients with colonic neoplasia highlights its biological role regulating oncogenic T-Ag expression in CRC.

Impact

JCV-specific miRNA is a candidate for the development of a non-invasive screening test, as well as therapeutic intervention for JCV-associated diseases.

Systematic analysis of human oncogenic viruses in colon cancer revealed EBV latency in lymphoid infiltrates

Background

Environmental factors may play a role in colon cancer. In this view, several studies investigated tumor samples for the presence of various viral DNA with conflicting results.

Findings

We undertook a systematic DNA analysis of 44 consecutive, prospectively collected primary tumor samples by real time and qualitative PCR for viruses of known or potential oncogenic role in humans, including polyomavirus (JCV, BKV, Merkel cell polyomavirus), HPV, HTLV, HHV-8 and EBV. Negative controls consisted of surgical resection margins. No evidence of genomic DNA fragments from tested virus were detected, except for EBV, which was found in a significant portion of tumors (23/44, 52%). Real-time PCR showed that EBV DNA was present at a highly variable content (median 258 copies in 10⁵ cells, range 15–4837). Presence of EBV DNA had a trend to be associated with high lymphocyte infiltration (p = 0.06, χ2 test), and in situ hybridization with EBER1-2 probes revealed latency in a fraction of these lymphoid cells, with just a few scattered plasma cells positive for BZLF-1, an immediate early protein expressed during lytic replication. LMP-1 expression was undetectable by immunohistochemistry.

Conclusions

These results argue against a significant involvement of the tested oncogenic viruses in established colon cancer.

Gastrointestinal malignancy and the microbiome

Microbial species participate in the genesis of a substantial number of malignancies-in conservative estimates, at least 15% of all cancer cases are attributable to infectious agents. Little is known about the contribution of the gastrointestinal microbiome to the development of malignancies. Resident microbes can promote carcinogenesis by inducing inflammation, increasing cell proliferation, altering stem cell dynamics, and producing metabolites such as butyrate, which affect DNA integrity and immune regulation. Studies in human beings and rodent models of cancer have identified effector species and relationships among members of the microbial community in the stomach and colon that increase the risk for malignancy. Strategies to manipulate the microbiome, or the immune response to such bacteria, could be developed to prevent or treat certain gastrointestinal cancers.

Seroprevalence rates of BKV, JCV, and MCPyV polyomaviruses in the general Czech Republic population

JC and BK polyomaviruses (JCV and BKV) infect humans and can cause severe illnesses in immunocompromised patients. Merkel cell polyomavirus (MCPyV) can be found in skin carcinomas. In this study, we assessed the occurrence of serum antibodies against MCPyV, BKV, and JCV polyomaviruses in a healthy population of the Czech Republic. Serum samples from 991 healthy individuals (age range: 6-64 years) were examined by enzyme-linked immunoassay (ELISA) using virus-like particles (VLPs) based on the major VP1 capsid proteins of these viruses. Overall, serum antibodies against MCPyV, JCV, and BKV were found in 63%, 57%, and 69%, respectively, of this population. For all three viruses, these rates were associated with age; the occurrence of antibodies against MCPyV and JCV was highest for those older than 59 years, while the occurrence of antibodies against BKV was highest in those aged 10-19 years and 20-29 years. This is the first large study to determine the seroprevalence rates for BKV, JCV, and MCPyV polyomaviruses in the general Czech Republic population.

Pulmonary tumors associated with the JC virus T-antigen in a transgenic mouse model

Many attempts to demonstrate the oncogenic role of the JC virus (JCV) have been partially successful in producing brain tumors, either by direct inoculation of JCV into the brain or in transgenic models in rodents. We previously reported the presence of JCV DNA with a relatively high incidence in pulmonary and digestive organs. However, we could not prove the oncogenic role of JCV. We prepared a transgene composed of the K19 promoter, specific to bronchial epithelium with the JCV T-antigen and established transgenic (TG) mice. Pulmonary tumors were detected without any metastasis in 2 out of 15 (13.3%) 16-month-old K19/JCV T-antigen TG mice. Using immunohistochemistry (IHC), these tumors showed JCV T-antigen, p53 and CK 19 expression, but not expression of nuclear and cytoplasmic β-catenin and insulin receptor substrate 1 (IRS1). IHC revealed the same expression pattern as in the bronchial epithelium of the TG mice. One tumor, which was examined with laser capture microdissection and molecular biological tools, demonstrated an EGFR mutation but not a K-ras mutation. We propose that the pulmonary tumors were derived from the JCV T-antigen in a TG mouse model. These findings shed light on pulmonary carcinogenesis.

Carcinogenic viruses and solid cancers without sufficient evidence of causal association

Viral infections are important risk factors for tumor development in humans. Selected types of cancers, either lymphomas or carcinomas, for which there is sufficient evidence in humans of a causal association with specific viruses, have been identified. Experimental and clinical data on the possible association of other tumor types and carcinogenic viruses are presently controversial. In this article, we review the current evidence on the relationship between breast, colorectal and lung cancers and carcinogenic viruses. The majority of the publications reviewed do not provide definitive evidence that the viruses studied are associated with breast, colon and lung cancers. However, since this association may be clinically relevant for some tumor subtypes (i.e., lung cancer and papillomaviruses), there is an urgent need for further investigation on this topic. Using innovative laboratory techniques for viral detection on well-defined tumor types, National and International networks against cancer should encourage and organize concerted research programs on viruses and solid cancer association.

The human JC polyomavirus (JCPyV): virological background and clinical implications

JC polyomavirus (JCPyV) was the first of now 12 PyVs detected in humans, when in 1964, PyV particles were revealed by electron microscopy in progressive multifocal leukoencephalopathy (PML) tissues. JCPyV infection is common in 35-70% of the general population, and the virus thereafter persists in the renourinary tract. One third of healthy adults asymptomatically shed JCPyV at approximately 50,000 copies/mL urine. PML is rare having an incidence of <0.3 per 100,000 person years in the general population. This increased to 2.4 per 1000 person years in HIV-AIDS patients without combination antiretroviral therapy (cART). Recently, PML emerged in multiple sclerosis patients treated with natalizumab to 2.13 cases per 1000 patients. Natalizumab blocks α4-integrin-dependent lymphocyte homing to the brain suggesting that not the overall cellular immunodeficiency but local failure of brain immune surveillance is a pivotal factor for PML. Recovering JCPyV-specific immune control, e.g., by starting cART or discontinuing natalizumab, significantly improves PML survival, but is challenged by the immune reconstitution inflammatory syndrome. Important steps of PML pathogenesis are undefined, and antiviral therapies are lacking. New clues might come from molecular and functional profiling of JCPyV and PML pathology and comparison with other replicative pathologies such as granule cell neuronopathy and (meningo-)encephalitis, and non-replicative JCPyV pathology possibly contributing to some malignancies. Given the increasing number of immunologically vulnerable patients, a critical reappraisal of JCPyV infection, replication and disease seems warranted.

Human polyomavirus JC reactivation and pathogenetic mechanisms of progressive multifocal leukoencephalopathy and cancer in the era of monoclonal antibody therapies

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by the neurotropic human polyomavirus JC (JCV) lytic infection of oligodendrocytes. PML was first described as a complication of lymphoproliferative disorders more than 50 years ago and emerged as a major complication of human immunodeficiency virus (HIV) infection in the 1980s. Despite the ubiquity of this virus, PML is rare and always seen in association with underlying immunosuppressive condition, such as HIV infection, autoimmune diseases, cancer, and organ transplantation. JCV remains quiescent in the kidneys, where it displays a stable archetypal non-coding control region (NCCR). Conversely, rearranged JCV NCCR, including tandem repeat patterns found in the brain of PML patients, have been associated with neurovirulence. The specific site and mechanism of JCV NCCR transformation is unknown. According to one model, during the course of immunosuppression, JCV departs from its latent state and after entering the brain, productively infects and destroys oligodendrocytes. Although the majority of PML cases occur in severely immunesuppressed individuals, PML has been increasingly diagnosed in patients treated with biological therapies such as monoclonal antibodies (mAbs) that modulate immune system functions: in fact, CD4+ and CD8+ T lymphopenia, resulting from this immunomodulatory therapy, are the primary risk factor. Furthermore, JCV reactivation in nonpermissive cells after treatment with mAbs, such as intestinal epithelial cells in Crohn's disease patients, in association with other host tumor-inducing factors, could provide valid information on the role of JCV in several malignancies, such as colorectal cancer.

Significance of infectious agents in colorectal cancer development

Colorectal cancer (CRC) is a major burden to healthcare systems worldwide accounting for approximately one million of new cancer cases worldwide. Even though, CRC mortality has decreased over the last 20 years, it remains the third most common cause of cancer-related mortality, accounting for approximately 600,000 deaths in 2008 worldwide. A multitude of risk factors have been linked to CRC, including hereditary factors, environmental factors and inflammatory syndromes affecting the gastrointestinal tract. Recently, various pathogens were added to the growing list of risk factors for a number of common epithelial cancers, but despite the multitude of correlative studies, only suggestions remain about the possible relationship between selected viruses and bacteria of interest and the CRC risk. United States military service members are exposed to various risk factors impacting the incidence of cancer development. These exposures are often different from that of many sectors of the civilian population. Thereby, cancer risk identification, screening and early detection are imperative for both the military health care beneficiaries and the population as a whole. In this review, we will focus on several pathogens and their potential roles in development of CRC, highlighting the clinical trials evaluating this correlation and provide our personal opinion about the importance of risk reduction, health promotion and disease prevention for military health care beneficiaries.

Molecular biology, epidemiology, and pathogenesis of progressive multifocal leukoencephalopathy, the JC virus-induced demyelinating disease of the human brain

Progressive multifocal leukoencephalopathy (PML) is a debilitating and frequently fatal central nervous system (CNS) demyelinating disease caused by JC virus (JCV), for which there is currently no effective treatment. Lytic infection of oligodendrocytes in the brain leads to their eventual destruction and progressive demyelination, resulting in multiple foci of lesions in the white matter of the brain. Before the mid-1980s, PML was a relatively rare disease, reported to occur primarily in those with underlying neoplastic conditions affecting immune function and, more rarely, in allograft recipients receiving immunosuppressive drugs. However, with the onset of the AIDS pandemic, the incidence of PML has increased dramatically. Approximately 3 to 5% of HIV-infected individuals will develop PML, which is classified as an AIDS-defining illness. In addition, the recent advent of humanized monoclonal antibody therapy for the treatment of autoimmune inflammatory diseases such as multiple sclerosis (MS) and Crohn's disease has also led to an increased risk of PML as a side effect of immunotherapy. Thus, the study of JCV and the elucidation of the underlying causes of PML are important and active areas of research that may lead to new insights into immune function and host antiviral defense, as well as to potential new therapies.

Human JCV infections as a bio-anthropological marker of the formation of Brazilian Amazonian populations

JC polyomavirus (JCV) is a member of the Polyomaviridae family. It presents a tropism to kidney cells, and the infection occurs in a variety of human population groups of different ethnic background. The present study investigated the prevalence of JCV infection among human populations from the Brazilian Amazon region, and describes the molecular and phylogenetic features of the virus. Urine samples from two urban groups of Belém (healthy subjects), one Brazilian Afro-descendant “quilombo” from the Rio Trombetas region, and native Indians from the Wai-Wai, Urubu-Kaapor, Tembé, Assurini, Arara do Laranjal, Aukre, Parakanã, Surui and Munduruku villages were investigated for the presence of the virus by amplifying VP1 (230 bp) and IG (610 bp) regions using a polymerase chain reaction. Nucleotide sequences (440 nucleotides, nt) from 48 samples were submitted to phylogenetic analysis. The results confirmed the occurrence of types A (subtype EU), B (subtypes Af-2, African and MY, Asiatic) and C (subtype Af-1) among healthy subjects; type B, subtypes Af-2 and MY, among the Afro-Brazilians; and type B, subtype MY, within the Surui Indians. An unexpected result was the detection of another polyomavirus, the BKV, among Afro-descendants. The present study shows, for the first time, the occurrence of JC and BK polyomaviruses infecting humans from the Brazilian Amazon region. The results show a large genetic variability of strains circulating in the region, infecting a large group of individuals. The presence of European, Asiatic and African subtypes associated to the ethnic origin of the population samples investigated herein, highlights the idea that JCV is a fairly good marker for studying the early migration of human populations, reflecting their early and late history. Furthermore, the identification of the specific mutations associated to the virus subtypes, suggests that these mutations have occurred after the entrance of the virus in the Amazon region of Brazil.

Does JC virus have a role in the etiology and prognosis of Egyptian colorectal carcinoma?

John Cunningham virus (JCV) encodes an oncogenic T-antigen, which is capable of interacting with key growth regulatory pathways. JCV definite role as causal agent of human cancer, still awaits final confirmation. The present study was conducted to assess the possible role of JCV in Egyptian colorectal carcinoma (CRC) and correlate the expression with the clinicopathological features and survival. JCV in situ hybridization (ISH) signals and large T antigen immunoreactivity were examined in 87 colonic specimens. Positive glandular JCV ISH signals were detected in 20%, 25% and 40% of normal, adenoma and CRC cases respectively. Stromal JCV ISH signals were identified in 26% of CRC cases and 5% of adenoma however, normal mucosa did not show stromal positivity with significant difference (p = 0.03). Glandular JCV expression was significantly associated with high grade (p = 0.03), high mitotic index (p=0.02) and low apoptotic index (p = 0.00). Positive stromal signals were significantly associated with low apoptosis (p = 0.00). No positive nuclear immunostaining of JCV large T antigen was detected in all specimens. JCV stromal expression was the 2nd most powerful indicator of short survival and bad prognosis (p = 0.03) in CRC patients. JCV might play an etiological role in CRC tumorogenesis and short survival in Egyptian CRC patients.