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

JC virus T-antigen expression in sporadic adenomatous polyps of the colon

BACKGROUND

JC virus (JCV) has been implicated in the pathogenesis of colorectal cancer; however, its role in premalignant lesions is unknown. The hypothesis that JCV DNA sequences and T-antigen (T-Ag) expression may be present in adenomatous polyps of the colon was tested. Furthermore, an association between JCV and microsatellite instability (MSI) was also sought in these lesions.

METHODS

DNA was extracted from 74 paraffin-embedded adenomatous polyps. JCV gene sequences were amplified by polymerase chain reaction (PCR), and the specificity confirmed by DNA sequencing. Immunohistochemical staining was performed to localize T-Ag expression in the adenomas using a monoclonal antibody. For microsatellite instability analysis, 5 mononucleotide repeat markers (BAT-25, BAT-26, NR-21, NR-24, and NR-27) were coamplified in a pentaplex PCR and analyzed for deletion mutations.

RESULTS

JCV T-Ag sequences were found in 82% (61 of 74) of adenomas, and T-Ag protein was expressed in 16% (12 of 74) of these polyps. The T-Ag staining was localized exclusively in the nuclei of adenoma cells, but never in the cytoplasm or the adjacent nonneoplastic cells. The prevalence of MSI-H and non-MSI-H (MSI-L/MSS) in adenomatous polyps was 9.5% (7 of 74) and 90.5% (67 of 74), respectively. Among the 61 adenomas that harbored JCV sequences, 8% (5 of 61) were MSI-H, and similarly among 12 adenomatous polyps expressing T-Ag protein 8% (1 of 12) of the adenomatous polyps were MSI-H.

CONCLUSIONS

JCV T-Ag DNA sequences are frequently present in adenomatous polyps of the colon, and T-Ag is expressed specifically in the nuclei of these premalignant lesions. This study indicates that JCV T-Ag is present in the early stage of colonic carcinogenesis. Future studies will be required to determine the molecular mechanism of carcinogenesis in these JCV-infected lesions.

Detection of the JC virus genome in lung cancers: possible role of the T-antigen in lung oncogenesis

The JC virus (JCV) infects a large proportion of the population worldwide and 80% to 90% of adults are seropositive and it may be activated in immunodeficient patients, resulting in progressive multifocal leukoencephalopathy. Recent reports described the possibility of its oncogenetic role in several malignancies. To clarify whether JCV might have a potential role in the genesis of lung cancers, we investigated the presence of its genome in 62 tumors, along with 23 samples of normal lung tissue, targeting the T-antigen, VP, and Agnoprotein by nested polymerase chain reaction/Southern blotting followed by direct DNA sequencing. Immunohistochemistry was performed to assess links between p53 and beta-catenin in lung cancers and the presence of T-antigen. The T-antigen was detected in 25 of 62 lung cancers but only 4 of 23 normal lung samples (P=0.048). In total, the JCV genome was present in 33 of the lung cancers and 10 of the normal samples. Furthermore, T-antigen was found in cancer cells in metastatic lymph nodes in 3 of 4 cases (P=0.042) and was more frequently detected in adenocarcinomas than in squamous cell carcinomas (P=0.038). Immunohistochemistry showed significant correlations between T-antigen and p53 (P=0.022) and also nuclear detection of beta-catenin (P=0.021). It is concluded that the JCV genome might be present in cancer cells in approximately half of all Japanese lung cancer cases, and that the T-antigen may play a role in oncogenesis of lung cancers through inactivation of p53 and dysregulation of the Wnt signaling pathway.

Molecular evolution of the prostate cancer susceptibility locus RNASEL: evidence for positive selection

Recent research implicates viral infection as a factor that may contribute to the risk of prostate cancer. Allelic variation at the RNASEL locus is associated with the risk of infection by a newly discovered retrovirus called XMRV, and with hereditary risk of prostate cancer. This evidence suggests that the RNASEL locus has undergone antagonistic coevolution with the retrovirus over evolutionary time. If this is the case, then both the RNASEL locus and the retrovirus should show evidence of positive selection. Here we use molecular-evolutionary methods to investigate the prediction that the RNASEL locus will exhibit evidence of positive selection. We find evidence that positive selection has acted on this locus over evolutionary time. We further find, using a Bayesian estimation procedure, that Asp541Glu, which was found to be associated with prostate cancer risk in Caucasians in a recent meta-analysis, shows an elevated probability of positive selection. Previous studies provide evidence for rapid evolution of the infection-mediating gag gene in the XMRV retrovirus. Taken together, these results suggest that antagonistic coevolution may have occurred between a specific host locus involved in immune defense (RNASEL) and a viral pathogen. In turn, genetic variation associated with this apparent coevolution may influence susceptibility to prostate cancer.

No excess risk for colorectal cancer among subjects seropositive for the JC polyomavirus

The human polyomaviruses JC virus (JCV) and BK virus (BKV) are oncogenic in experimental systems and commonly infect humans. JCV DNA has been reported to be present in human colon mucosa and in colorectal cancers. To investigate whether the risk for colorectal cancer is associated with JCV or BKV infection, we performed a case-control study nested in the Janus biobank, a cohort of 330,000 healthy Norwegian subjects. A 30-year prospective follow-up using registry linkages identified 386 men with colorectal cancer who had baseline serum samples taken >3 months before diagnosis. Control subjects were matched for sex, age and date of blood sampling and county of residence. Seropositivity for JCV or BKV had high (97-100%) sensitivity for detection of viral DNA-positive subjects and discriminated the different polyomaviruses. Seropositivity was mostly stable over time in serial samples. The relative risk for colorectal cancer among JCV seropositive subjects was 0.9 (95% CI: 0.7-1.3) and the BKV-associated relative risk was 1.1 (95% CI: 0.8-1.5). Determining seropositivity using alternative cutoffs also found no evidence of excess risk. In summary, this prospective study found no association between JCV or BKV infections and excess risk for colorectal cancer.

Transforming Activities of JC Virus Early Proteins

Polyomaviruses, as their name indicates, are viruses capable of inducing a variety of tumors in vivo. Members of this family, including the human JC and BK viruses (JCV, BKV), and the better characterized mouse polyomavirus and simian virus 40 (SV40), are small DNA viruses that commandeer a cell's molecular machinery to reproduce themselves. Studies of these virus-host interactions have greatly enhanced our understanding of a wide range of phenomena from cellular processes (e.g., DNA replication and transcription) to viral oncogenesis. The current chapter will focus upon the five known JCV early proteins and the contributions each makes to the oncogenic process (transformation) when expressed in cultured cells. Where appropriate, gaps in our understanding of JCV protein function will be supplanted with information obtained from the study of SV40 and BKV.

High prevalence of human polyomavirus JC VP1 gene sequences in pediatric malignancies

The oncogenic potential of human polyomavirus JC (JCV), a ubiquitous virus that establishes infection during early childhood in approximately 70% of the human population, is unclear. As a neurotropic virus, JCV has been implicated in pediatric central nervous system tumors and has been suggested to be a pathogenic agent in pediatric acute lymphoblastic leukemia. Recent studies have demonstrated JCV gene sequences in pediatric medulloblastomas and among patients with colorectal cancer. JCV early protein T-antigen (TAg) can form complexes with cellular regulatory proteins and thus may play a role in tumorigenesis. Since JCV is detected in B-lymphocytes, a retrospective analysis of pediatric B-cell and non-B-cell malignancies as well as other HIV-associated pediatric malignancies was conducted for the presence of JCV gene sequences. DNA was extracted from 49 pediatric malignancies, including Hodgkin disease, non-Hodgkin lymphoma, large cell lymphoma and sarcoma. Polymerase chain reaction (PCR) was conducted using JCV specific nested primer sets for the transcriptional control region (TCR), TAg, and viral capsid protein 1 (VP1) genes. Southern blot analysis and DNA sequencing were used to confirm specificity of the amplicons. A 215-bp region of the JCV VP1 gene was amplified from 26 (53%) pediatric tumor tissues. The JCV TCR and two JCV gene regions were amplified from a leiomyosarcoma specimen from an HIV-infected patient. The leiomyosarcoma specimen from the cecum harbored the archetype strain of JCV. Including the leiomyosarcoma specimen, three of five specimens sequenced were typed as JCV genotype 2. The failure to amplify JCV TCR, and TAg gene sequences in the presence of JCV VP1 gene sequence is surprising. Even though JCV TAg gene, which is similar to the SV40 TAg gene, is oncogenic in animal models, the presence of JCV gene sequences in pediatric malignancies does not prove causality. In light of the available data on the presence of JCV in normal and cancerous colon epithelial tissue and our data on amplification of JCV from the cecum of an HIV-infected pediatric patient, further studies are warranted on the role of colon epithelium in the pathogenesis of JCV infection.

Microsatellite instability and MLH1 promoter hypermethylation in colorectal cancer

Colorectal cancer (CRC) is caused by a series of genetic or epigenetic changes, and in the last decade there has been an increased awareness that there are multiple forms of colorectal cancer that develop through different pathways. Microsatellite instability is involved in the genesis of about 15% of sporadic colorectal cancers and most of hereditary nonpolyposis cancers. Tumors with a high frequency of microsatellite instability tend to be diploid, to possess a mucinous histology, and to have a surrounding lymphoid reaction. They are more prevalent in the proximal colon and have a fast pass from polyp to cancer. Nevertheless, they are associated with longer survival than stage-matched tumors with microsatellite stability. Resistance of colorectal cancers with a high frequency of microsatellite instability to 5-fluorouracil-based chemotherapy is well established. Silencing the MLH1 gene expression by its promoter methylation stops the formation of MLH1 protein, and prevents the normal activation of the DNA repair gene. This is an important cause for genomic instability and cell proliferation to the point of colorectal cancer formation. Better knowledge of this process will have a huge impact on colorectal cancer management, prevention, treatment and prognosis.

JC [corrected] virus detection in human tissue specimens

AIM

To clarify the advantages and disadvantages of different detection methods for Jamestown Canyon virus (JCV) in human tissue specimens.

METHODS

Specimens of lung and gastric carcinomas, and normal lung tissue, gastric mucosa, and tonsil were examined for T-antigen, VP and agnoprotein of JCV by nested PCR, Southern blotting and sequencing. JCV load targeting T-antigen was evaluated by real-time PCR, and JCV existence morphologically by immunohistochemistry, in-situ hybridisation (ISH) and PCR. For these experiments, the JCI cell line (JCV cultured neuroblastoma cell line) was employed as positive control.

RESULTS

In lung and gastric carcinomas, T-antigen, VP and agnoprotein of JCV could be detected by nested PCR whose products were confirmed by Southern blots and sequencing. With real-time PCR, frozen samples of gastric carcinomas gave better detection of JCV than their corresponding paraffin-embedded tissues (p<0.05). The positive rate of JCV was high in lung carcinoma, compared with normal lung tissue (p<0.05). It was the same for JCV copies in gastric carcinoma (p<0.05). Only the positive control exhibited JCV in the nucleus by ISH and immunohistochemistry. In-situ PCR showed that JCV genomic DNA was located in the nucleus of the carcinoma cell, some alveolar epithelial cells, and tonsil lymphocytes. In ISH and PCR, NBT/BCIP colouring was stronger than Fuchsin.

CONCLUSIONS

Nested PCR whose amplicons should be confirmed by Southern blot and sequencing was a comparatively sensitive approach to detect JCV genomic DNA in human non-neural tissues. Real-time PCR might be employed to quantify copy number of JCV. In-situ PCR was a good method to observe the JCV location in cells, given appropriate modulation of amplification cycles. Combinations of various approaches will be adopted to explore the oncogenic roles of JCV in malignancies.

Viral proteomics: a promising approach for understanding JC virus tropism

The human polyomavirus JC virus (JCV) is responsible for the CNS demyelination observed in cases of progressive multifocal leukoencephalopathy. The JCV regulatory region (promoter) is a hypervariable, noncoding, nucleotide sequence positioned between the early and late protein-coding regions in the viral genome. Selective binding of cellular transcription factors to this promoter region participates in the control of viral tropism. Hence, further study of these proteins might provide new insights into JCV tropism and associated pathogenesis. This review gives an overview of viral proteomics - the study of all proteins expressed from the viral gene transcripts, and all the cellular proteins that play a role in JCV tropism. It also describes a new biochemical approach for studying relevant JCV promoter-binding proteins, which is an anchored-JCV transcriptional promoter (ATP) assay. An ATP assay utilizes the product of PCR-amplified JCV promoter sequences coupled with Sepharose beads in order to capture and isolate cellular nuclear proteins with specific promoter-binding affinity for analysis. Proteins that bind to JCV-ATPs can be eluted and subjected to proteomic analysis. Insights from this approach may improve the understanding of viral and cellular parameters that control JCV tropism.

Management of infections by the human polyomavirus JC: past, present and future

Progressive multifocal leukoencephalopathy is a fatal demyelinating disease caused by infection of oligodendrocytes by the human polyomavirus known as JC virus. Over the past 10 years, the disease has been documented almost exclusively in AIDS patients, who constitute a rapidly growing population of immunosuppressed individuals. More recently, progressive multifocal leukoencephalopathy has also been described in patients undergoing solid organ or cell transplant, as a result of immunosuppressive therapy to avoid graft rejection. Although there are several reports of successful treatment of progressive multifocal leukoencephalopathy, large-scale prospective trials have been few, and with mixed results. As more is discovered about the biology of JC virus infection and advances are made in targeted parenchymal delivery of therapeutic agents, there is hope for the development of an effective therapy for progressive multifocal leukoencephalopathy.

High JC virus load in gastric cancer and adjacent non-cancerous mucosa

The JC virus (JCV) infects a large proportion of the worldwide population and approximately 90% of adults are seropositive. Recent reports have described the possibility of its oncogenetic role in several malignancies. The aim of the present study was to assess the oncogenetic significance of JCV for gastric cancer. Twenty-two sample pairs of fresh tumor and adjacent non-cancerous tissue (ANCT) as well as 10 normal gastric mucosa specimens were investigated on the basis of nested polymerase chain reaction (PCR) followed by Southern blotting, DNA direct sequencing, real-time PCR, in situ PCR and immunohistochemistry. The T antigen sequence was detected in 86.4% of gastric cancers and ANCT, and in 100% of the normal mucosa samples, as for virus capsid protein, 54.1%, 68.1% and 70%, respectively. A generally low incidence was noted for agnoprotein. The JCV DNA load was approximately 10-fold higher in both gastric cancers and paired ANCT (4784 +/- 759 and 5394 +/- 1466 copies/microg DNA, respectively) than in normal gastric tissue (542.4 +/- 476.0 copies/microg DNA, P < 0.0001). In situ PCR revealed sporadic JCV genome-positive cancer cells and foveolar epithelial cells. T antigen protein expression assessed by immunohistochemistry was detected only in one case (1/22; 4.5%), probably because the half life of T antigen might be short. It was concluded that the gastric epithelium in most Japanese people is infected with JCV at a low rate but levels of infection are increased markedly in both cancer cells and ANCT, indicating that multiplication of JCV copies might be a risk factor and a background for gastric carcinogenesis.

Distribution of human polyomaviruses, adenoviruses, and hepatitis E virus in the environment and in a drinking-water treatment plant

Large numbers of viruses are excreted in human feces and urine, which even at low concentrations may cause illness when ingested. Some of these viruses have not been traditionally monitored in terms of waterborne diseases and are considered emergent viruses, such as hepatitis E virus (HEV) and JC and BK polyomavirus (JCPyV and BKPyV). The high prevalence of human adenoviruses (HAdV) and polyomaviruses, which both show DNA genomes, in sewage from widely divergent areas has suggested the relevance of evaluating these viruses as possible indicators of viral contamination. The concentration of these viruses was analyzed in sewage and river water and after treatment in a drinking-water treatment plant including chlorination, flocculation, ozonation, and granulate active carbon (GAC) filtration. Samples of GAC-filtered water were collected before a second chlorination treatment. The river used as a source of fresh water presented an average concentration of 2.6 x 10(1) JCPyV and 4 x 10(2) HAdV GC (genome copies)/L. A removal of 2 logarithms (99%) of HAdV and JCPyV was observed in the drinking-water treatment plant. All the GAC-filtered water samples studied contained HAdV, with a mean value of 4.3 HAdV GC/L. HEV strains belonging to genotype 3 were frequently detected in low concentrations in urban sewage and in biosolids or sewage containing swine feces but not in the river water samples studied. The detection of viruses by molecular techniques is useful for genetically describe emergent viruses in community wastewaters and water supplies. Quantification of JCPyV and HAdV using quantitative real-time PCR (QPCR) may be useful for evaluating virus removal efficiency in water treatment plants and as an index of the virological quality of water and of the potential presence of human viruses.

DNA tumor viruses and human cancer

There is a strong association between viruses and the development of human malignancies. A group of oncogenic DNA viruses exists in the human population today, members of which serve as infectious agents of cancer worldwide. The group includes the Epstein-Barr virus, Kaposi's sarcoma-associated herpesvirus, human papillomaviruses and human polyomaviruses. Globally, it is estimated that 20% of all cancers are linked to infectious agents. Studies of DNA viruses have contributed to our current understanding of the key molecular players in the transformation process. Research has also shed light on the molecular mechanisms of tumorigenesis that are employed by these viruses and there are indications that cofactors could be required for viral oncogenicity in some cases.

Immunoglobulin G, A, and M responses to BK virus in renal transplantation

Immunoglobulin G (IgG), IgA, and IgM antibodies were measured in serum samples from 71 organ donors, 81 kidney transplant recipients at transplantation, and 67 patients during the posttransplant period by using a virus-like particle-based enzyme-linked immunosorbent assay (ELISA). BK virus (BKV) and JC virus DNA were detected in urine and plasma by real-time PCR. IgG antibodies to BKV were demonstrated in the majority (80.3 to 100%) of patients irrespective of clinical category, but titers were highest in patients with active viral replication. IgA antibodies were present with greater frequency (72.7 to 81.3% versus 0 to 23.6%; P < 0.001) and higher titer (mean optical density, 0.11 to 0.15 versus 0.05 to 0.08; P < 0.001) in patients who were BKV DNA positive than those who were BKV DNA negative. IgM antibodies showed a similar pattern of reactivity but lower frequency in the setting of active viral replication (9.1 to 43.7% versus 0 to 1.4%; P < 0.001). A rise in IgG level of >0.577 optical density (OD) units or a rise in IgA or IgM level of >0.041 OD units was strongly associated with active viral replication. Urine viral load showed a positive correlation with IgM titer (r = 0.22) but a negative correlation with IgG titer (r = -0.28) and IgA titer (r = -0.1). Chronic dialysis patients typically did not have serologic or virologic evidence of active BKV infection. Anti-BKV titers did not rise in patients with JC viruria. In conclusion, measurement of anti-BKV antibody titer and class response can be used to detect the onset of viral replication. ELISAs can be quite specific despite considerable sequence homology between BK virus and JC virus.

Oncogenic T-antigen of JC virus is present frequently in human gastric cancers

BACKGROUND

JC virus (JCV) is a polyomavirus that commonly infects humans and is the causative agent of progressive multifocal leukoencephalopathy in immune-compromised patients. An association between JCV and human cancers long has been suspected, because this virus induces brain tumors in several animal models. The oncogenic potential of JCV is mediated by a transforming protein, the T-antigen (T-Ag), which is a multifunctional protein that transforms cells through interactions with various growth-regulatory genes, including p53 and pRb, and by stabilizing beta-catenin. Previously, the laboratory at the authors' institution demonstrated that JCV is present frequently in the human gastrointestinal tract and may play a role in colorectal carcinogenesis. However, to date, no studies have determined whether JCV sequences are present specifically in gastric cancers. The current study was designed to investigate whether JCV sequences and expression are found in human gastric cancers.

METHODS

DNA was extracted from 23 paraffin embedded and 14 frozen gastric cancer specimens. For the detection of JCV gene sequences, polymerase chain reaction amplifications were performed using gene-specific primers for T-Ag, VP-1 (a JCV capsid gene), and the viral regulatory region (or transcriptional control region). Immunohistochemical staining was performed with an anti-T-Ag monoclonal antibody to detect protein expression.

RESULTS

Twenty-one of 37 gastric cancers (57%) harbored JCV T-Ag sequences, and 13 of 37 gastric cancers (30%) contained VP-1 sequences. T-Ag sequences also were found in adjacent nonneoplastic mucosa. In addition, JCV regulatory region sequences were present frequently in gastric cancers and adjacent nonneoplastic mucosa. T-Ag protein expression was found in 9 of 23 gastric cancers (39%), whereas no expression was observed in any of the nonneoplastic tissues.

CONCLUSIONS

To the authors' knowledge, this is the first demonstration of the presence of JCV T-Ag expression in human gastric cancers. These findings suggest a possible role for this polyomavirus in gastric carcinogenesis.

Pharmacotherapeutic options for the management of human polyomaviruses

Polyomaviruses [BK virus (BKV), JC virus (JCV) and simian virus 40 (SV40)] have been known to be associated with diseases in humans for over thirty years. BKV-associated nephropathy and JCV-induced progressive multifocal leukoencephalopathy (PML) were for many years rare diseases occurring only in patients with underlying severe impaired immunity. Over the past decade, the use of more potent immunosuppression (IS) in transplantation, and the Acquired Immune Deficiency Syndrome (AIDS) epidemic, have coincided with a significant increase in the prevalence of these viral complications. Prophylactic and therapeutic interventions for human polyomavirus diseases are limited by our current understanding of polyomaviral pathogenesis. Clinical trials are limited by small numbers of patients affected with clinically significant diseases, lack of defined risk factors and disease definitions, no proven effective treatment and the overall significant morbidity and mortality associated with these diseases. This chapter will focus on a review of the current and future research related to therapeutic targets and interventions for polyomavirus-associated diseases.

The polyomavirus, JCV and its involvement in human disease

The human neurotropic polyomavirus, JC virus (JCV), is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system that occurs mainly in immunosuppressed patients. JCV has also been found to be associated with human tumors of the brain and other organs. In this chapter, we describe JC virus and its role in human diseases.

Polyomavirus in human cancer development

In animal studies, polyoma viruses have been found to be viral agents for oncogenesis and to produce a wide range of pathological lesions in experimental animals, including a variety of neoplastic tumors. The human polyoma viruses (JCV and BKV), along with their simian cousin (SV40), are ubiquitous viruses that are primarily associated with progressive multifocal leukoencephalolopathy (PML) and hemorrhagic cystitis, respectively, under specific conditions in immunocompromized individuals. Currently, polyoma viruses are now undergoing increasing scrutiny as possible causes for several human cancers. Evidence has been mounting recently that JCV, BKV as well as SV40 are potential oncogenic viruses in humans as well.

Association of JC virus T-antigen expression with the methylator phenotype in sporadic colorectal cancers

BACKGROUND & AIMS

JC virus (JCV) is a polyomavirus that ubiquitously infects humans and has been implicated in various human cancers. JCV encodes a "transforming" gene, T-antigen (T-Ag), which is believed to mediate the oncogenic potential of the virus. We have previously shown that JCV DNA sequences are usually present in human colorectal cancers (CRCs), and we have provided in vitro evidence that JCV can induce chromosomal instability (CIN) in CRC cells. This study tests the hypothesis that JCV T-Ag expression correlates with one or more forms of genomic or epigenetic instability in sporadic CRCs.

METHODS

We characterized 100 sporadic CRCs for microsatellite instability (MSI) and CIN. PCR amplifications were performed for T-Ag sequences, and immunohistochemical (IHC) staining was performed to detect T-Ag expression. De novo methylation of the promoter regions of nine putative tumor suppressor genes thought to play a role in colorectal carcinogenesis was studied by methylation-specific PCR.

RESULTS

JCV T-Ag DNA sequences were found in 77% of the CRCs and 56% of these cancers (or 43% of the total) expressed T-Ag by IHC. Significant associations were observed between T-Ag expression and CIN in CRCs (P = .017) and between T-Ag expression and promoter methylation of multiple genes (P = .01).

CONCLUSIONS

The association between T-Ag expression and promoter methylation in CRC suggests that this viral oncogene may induce methylator phenotype and that JCV may be involved in CRC through multiple mechanisms of genetic and epigenetic instability.

Evolving knowledge and therapy of inflammatory bowel disease

With recent advances in the understanding of its pathophysiology, inflammatory bowel disease has become a very active area for the development of novel therapeutic agents. New targets for biologics include cytokines involved in T-cell activation, with antibodies directed against IL-12 and interferon-gamma. Selective adhesion molecule blockade has produced promising, though mixed, results. Recombinant human granulocyte-macrophage colony-stimulating factor might be effective in active Crohn's disease, presumably through stimulation of intestinal innate immune responses. With increasing evidence for a crucial role for luminal flora in maintaining the health of the bowel, strategies to manipulate intestinal bacteria using probiotics and prebiotics are being actively investigated as well.

Real-time, quantitative PCR assays for the detection of virus-specific DNA in samples with mixed populations of polyomaviruses

Mixtures of polyomaviruses can be present in the central nervous system, the gastrointestinal tract, the genitourinary tract, blood, and urban sewage. We have developed 12 primer/probe sets (four per virus) for real-time, quantitative PCR assays (TaqMan) that can specifically detect BKV, JCV, and SV40 genomes present in mixtures of these viruses. The specificities of these primer/probe sets were determined by evaluating their level of interaction with the DNA from other polyomaviruses and their ability to estimate the number of copies of homologous viral DNA in blinded samples of defined mixtures of three polyomaviral DNAs. Three early region and three late region primer/probe sets determined, within a two-fold range, the number of copies of their respective DNAs. Four sets of SV40 primer/probes also detected 1.1-2.4 copies of SV40 DNA per COS-1 cell, cells estimated to contain a single copy of SV40 DNA. Three JCV primer/probe sets detected 3.7-4.2 copies per cell of JCV DNA in the JCV-transformed cell line M1-HR, cells estimated to contain between 0.5 and 1 copy of the JCV genome. We suggest that the virus-specific primer/probe sets in this study be considered sufficiently characterized to initiate the quantification of polyomavirus DNA in biological samples.

Frequent detection of polyomaviruses in stool samples from hospitalized children

BACKGROUND

Infection with BK virus (BKV) generally occurs early during life, but its mode of transmission has not been clearly defined. We tested the hypothesis that polyomavirus shedding in stool may be a source of BKV exposure.METHODS. Pediatric stool and rectal swab samples were tested for the presence of polyomavirus DNA by a polymerase chain reaction (PCR) assay that could detect a conserved region in the large T antigen gene of BKV, JC virus (JCV), and simian virus 40 (SV40). The specific viruses detected by this assay were confirmed by DNA sequence analysis of the PCR amplicons.Results. Of 120 samples collected from 99 patients, 54 (45.0%) were positive for polyomavirus DNA. Of the 99 patients, 46 (46.5%) had at least 1 positive sample, with 38 (38.4%) positive for BKV and 8 (8.1%) positive for SV40. JCV was not detected. There was no association between polyomavirus fecal shedding and age, sex, race/ethnicity, immune status, or symptoms of gastrointestinal disease in the children studied. The BKV strains detected displayed polymorphisms in the T antigen sequence.Conclusions. Polyomaviruses are frequently present in stool samples from hospitalized children. These findings suggest that fecal-oral transmission of BKV may play a role in the ubiquity of infection.

Human polyomaviruses and brain tumors

Polyomaviruses are DNA tumor viruses with small circular genomes. Three polyomaviruses have captured attention with regard to their potential role in the development of human brain tumors: JC virus (JCV), BK virus (BKV), and simian vacuolating virus 40 (SV40). JCV is a neurotropic polyomavirus that is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system occurring mainly in AIDS patients. BKV is the causative agent of polyomavirus-associated nephropathy (PVN) which occurs after renal transplantation when BKV reactivates from a latent state during immunosuppressive therapy to cause allograft failure. SV40, originating in rhesus monkeys, gained notoriety when it entered the human population via contaminated polio vaccines. All three viruses are highly oncogenic when injected into the brain of experimental animals. Reports indicate that these viruses, especially JCV, are associated with brain tumors and other cancers in humans as evidenced from the analysis of clinical samples for the presence of viral DNA sequences and expression of viral proteins. Human polyomaviruses encode three non-capsid regulatory proteins: large T-antigen, small t-antigen, and agnoprotein. These proteins interact with a number of cellular target proteins to exert effects that dysregulate pathways involved in the control of various host cell functions including the cell cycle, DNA repair, and others. In this review, we describe the three polyomaviruses, their abilities to cause brain and other tumors in experimental animals, the evidence for an association with human brain tumors, and the latest findings on the molecular mechanisms of their actions.

Lack of association of polyomavirus and herpesvirus types 6 and 7 in human lymphomas

BACKGROUND

The association of viruses with several human tumors has been studied for almost 100 years, and it remains a very controversial issue. Due to the fact that the presence of polyomaviruses and herpes viruses reportedly are associated with lymphomas, albeit with striking results and differences between the many studies, the authors undertook a study into the presence of viral sequences of polyomavirus (BK virus, JC virus, and especially simian virus 40 [SV40]) in human lymphomas in an attempt to explain this contradictory association. To complete the study, the presence of different virus types from the herpesviriridae family were analyzed, such as herpesvirus type 6 (HHV6), HHV7, HHV8, and Epstein-Barr virus, in human lymphomas.

METHODS

DNA was isolated from 83 frozen human lymphoma samples, and different polymerase chain reaction techniques were used to find polyomavirus and herpesvirus sequences in these samples. To assess the incidence of the presence of sequences in lymphomas, a parallel analysis was made of 53 samples from normal donor spleen lymphocytes. Positive samples were analyzed for polyomavirus sequences by immunohistochemistry.

RESULTS

Polyomavirus sequences were detected in 9 of 83 lymphomas (11%), and SV40 sequences could be confirmed in only 1 lymphoma. Immunohistochemistry for large-T antigen was negative in all samples. Herpesviruses were detected in 53 of 83 lymphomas (63.9%), were detected more frequently in Hodgkin lymphomas (80%) than in non-Hodgkin lymphomas (58.7%), and were detected in > 60% of normal spleen lymphocytes.

CONCLUSIONS

The current results did not support a clear association of polyomavirus and HHV6 or HHV7 with lymphomas; HHV6 and HHV7 sequences were detected in a similar percentage of normal samples and lymphomas. The lack of significant differences between normal and malignant lymphocytes and the absence of viral protein expression in the tumor cells did not allow the establishment of a clinical correlation between polyomaviruses or HHVs (HHV6, HHV7, HHV8) and lymphomas. Nevertheless, because viral products can be lost during tumor progression, and because host factors can modulate the oncogenic role of some viruses, the hypothetical role of these viruses cannot be discarded completely.

Detection of JC virus DNA sequences and expression of viral T antigen and agnoprotein in esophageal carcinoma

BACKGROUND

The human polyomavirus JC virus (JCV) causes progressive multifocal leukoencephalopathy. Subclinical infection with JCV occurs in 85-90% of the population worldwide. The virus usually remains latent but can reactivate under immunosuppressive conditions, resulting in progressive multifocal leukoencephalopathy. JCV is oncogenic in experimental animals and is associated with human brain tumors. JCV is found in normal mucosa of the gastrointestinal tract, and some colon carcinomas express the oncogenic JCV T-antigen protein. The objective of this study was to examine the presence of JCV DNA sequences and JCV protein expression in normal and malignant human esophageal tissues.

METHODS

The authors examined the presence of JCV DNA sequences and protein expression in normal and malignant human esophageal tissues. Seventy well characterized biopsy specimens from patients with a spectrum of esophageal disorders were studied by immunohistochemistry, and 18 specimens were analyzed further by polymerase chain reaction amplification.

RESULTS

JC viral DNA was isolated from 11 of 13 normal esophageal biopsy specimens (85%) and from 5 of 5 esophageal carcinomas (100%). Using immunohistochemistry, JCV T antigen was detected in 10 of 19 carcinomas (53%), agnoprotein was detected in 8 carcinomas (42%), p53 tumor suppressor was detected in 11 carcinomas (58%), and beta-catenin was detected in 4 carcinomas (21%). Zero of 51 normal, benign, and premalignant esophageal samples expressed viral proteins. Laser-capture microdissection verified the presence and specificity of JCV DNA sequences. beta-Catenin and p53 were colocalized with JCV T-antigen in the nuclei of neoplastic cells.

CONCLUSIONS

The results provide evidence for infection of gastrointestinal tract cells by JCV and suggest a potential role of JCV in the development of upper digestive tract carcinomas.

Assessment of JC polyoma virus in colon neoplasms

PURPOSE

Research data have recently emphasized an intriguing association of JC polyoma virus with colon carcinogenesis. Tumorigenicity of JC virus is attributed to the T-antigen of its Mad-1 variant. Controversy arose when another research group did not confirm this association. The purpose of this study was to detect JC virus in a series of colon neoplasms from Greek patients.

METHODS

A nested polymerase chain reaction assay was used to detect JC virus in 80 cancerous, 25 adenomatous specimens of large bowel, and 20 colonoscopic biopsy samples from normal patients without colorectal neoplasia. Quantitation of JC virus DNA was performed by real-time polymerase chain reaction.

RESULTS

JC polyoma virus nucleotide sequence was detected in 61 percent of colon adenocarcinomas and in 60 percent of adenomas, at a viral load of 9 x 10(3) to 20 x 10(3) copies/microg DNA. Adjacent normal mucosa in 35 positive colon adenocarcinoma specimens, and normal mucosa from six patients of the control group, had low viral loads (50-450 copies/microg DNA).

CONCLUSIONS

JC polyoma virus genome is present in colon neoplasms. JC virus detection in adenomas at comparable viral loads to malignant tumors suggests its implication at early steps of colonic carcinogenesis. Taking into consideration other published data, infection of colonic epithelium with JC virus might be a prime candidate for a role in chromosomal and genomic instability.

Constraints imposed by supercoiling on in vitro amplification of polyomavirus DNA

Previous attempts to identify oncogenic polyomaviruses in human cancers have yielded conflicting results, even with the application of PCR technology. Here, it was considered whether the topological features of the polyomavirus genome interfere with efficient PCR amplification. Plasmid and SV40 DNAs were used as a model system for comparing the amplification efficiency of supercoiled, circular relaxed and linear templates. It was found that detection of circular templates required 10 times more molecules than detection of identical but linear templates. Supercoiling hindered the in vitro amplification of SV40 circles by a factor of 10, and erratic amplification of supercoiled SV40 occurred with subpicogram amounts of template. Accordingly, topoisomerase I treatment of DNA improved the PCR detection of supercoiled SV40, significantly decreasing the number of false-negative samples. Previously described, yet controversial, polyomavirus presence in human tissues should be reconsidered and topoisomerase I-sensitive polyomavirus amplification might help to detect polyomavirus genomes in mammalian tissues.

The optimal rate of chromosome loss for the inactivation of tumor suppressor genes in cancer

Many cancers are characterized by chromosomal instability (CIN). This phenotype involves the deletion and duplication of chromosomes or chromosome parts and results in a high degree of aneuploidy. The role of CIN for cancer progression is a very important, yet unresolved question. It has been argued that CIN contributes to cancer initiation because chromosome loss can unmask a mutated tumor suppressor (TSP) gene. At the same time, CIN is costly for the cell because it destroys the genome and therefore compromises clonal expansion. Here, we use mathematical models to determine whether CIN can accelerate the generation and expansion of TSP(-/-) cells in the context of this tradeoff. Comparing cells with different degrees of CIN, we find that the emergence and growth of TSP(-/-) cells is optimized if the rate of chromosome loss is of the order of 10(-3) to 10(-2). This result is very robust, is independent of parameter values, and coincides with experimental measures using colon cancer cell lines. However, if we consider all of the steps in the pathway, including the generation of the CIN phenotype from stable cells, then it turns out that the emergence and growth of TSP(-/-) cells is never accelerated by CIN. Therefore, CIN does not arise because it accelerates the accumulation of adaptive mutations. Instead, it arises for other reasons, such as environmental factors, and is subsequently fine-tuned by selection to minimize the time to further cancer progression by means of the inactivation of TSP genes.

Primary central nervous system lymphoma expressing the human neurotropic polyomavirus, JC virus, genome

B lymphocytes are known as a potential site for latency and reactivation of the human neurotropic polyomavirus, JC virus (JCV). In light of recent studies on the oncogenicity of JCV and the transforming ability of the JCV early protein, T antigen, we investigated the association of JCV with B-cell lymphomas of the central nervous system. Examination of 27 well-characterized clinical specimens by gene amplification and immunohistochemistry revealed the presence of DNA sequences corresponding to the JCV early genome and the late Agnoprotein in 22 samples and the JCV late genome encoding the viral capsid proteins in 8 samples. Expression of T antigen and that of Agnoprotein by immunohistochemistry were each detected in six specimens. No evidence of the production of viral capsid proteins was observed, ruling out productive infection of JCV in the tumor cells. The results from laser capture microdissection verified the presence of JCV T-antigen sequences in tumor cells with positive immunoreactivity to antibodies against the viral proteins T antigen and Agnoprotein. Due to previous reports demonstrating an association of the Epstein-Barr virus (EBV) with transformation of B lymphocytes, EBV DNA sequences and the EBV transforming protein, latent membrane protein 1 (LMP1), were analyzed in parallel. EBV LMP1 DNA sequences were detected in 16 of 23 samples, and LMP1 expression was detected in 16 samples, 5 of which exhibited positive immunoreactivity to JCV proteins. Double labeling demonstrated coexpression of JCV T antigen and EBV LMP1 in the same cells. The detection of the JCV genome in large numbers of B-cell lymphomas and its coexistence with EBV suggest a potential role for JCV in the pathogenesis of primary CNS lymphoma.

No Evidence of an Association of JC Virus and Colon Neoplasia

JC virus (JCV) is an ubiquitous human polyomavirus that frequently resides in the kidneys of healthy individuals and is excreted in the urine of a large proportion of the adult population. Polyomaviruses are associated with disease largely in immunocompromised individuals (progressive multifocal leukoencephalopathy). Colorectal cancers can show chromosome instability and it was hypothesized that JCV may account for some of this instability. We screened urine from 45 healthy donors and 233 colorectal cancer/normal tissue pairs for the presence of JCV sequences using a Taqman assay. This assay could detect 1 virus genome in 10 human genomes. In the urine samples, we found an infection rate of approximately 70%. The JCV isolates in these samples could be categorized into four JCV types (2B, 4, 7, and 8), none of which had a rearranged regulatory region. Among the colon tissues, one normal tissue (&lt;0.5%) and none of the matched tumors tested positive for JCV. There is no evidence in these data to indicate that JCV is the cause of genetic instability in colorectal cancer.

Evolution of virulence

At the close of the 19th century, the germ theory had generated a new understanding of the causes of acute infectious diseases and revealed new directions for study. This understanding contributed to the greatest improvements in health in the history of medicine. At the end of the 20th century, the second stage of this disciplinary development is occurring. The old germ theory is being expanded into a new germ theory, which, by integrated the full spectrum of biologic disciplines. This new germ theory is emphasizing how environments and human activities influence the characteristics of infectious agents and the broader role of infection as a cause of chronic diseases.

Molecular analysis of JC virus genotypes circulating among the Italian healthy population

JC virus (JCV) is an unique virus, but eight different JCV genotypes and various subtypes have been individuated, with a geographic distribution that has been described in general but still needs to be detailed. To define JCV genotype epidemiology in Italy, the authors collected urine from 211 healthy individuals living in Northern, Central, and Southern Continental Italy, and in the two main Italian islands. As screening, JCV DNA was searched using a polymerase chain reaction (PCR) designed to amplify the highly conserved large T (LT) antigen-coding region. Then, to define JCV genotype and trascriptional control region (TCR) organization, fragments of major capsid protein (VP1) and TCR region were amplified and subjected to nucleotide sequencing. The mean frequency of JCV viruria was of 46%, without differences among the four geographically divided groups and between females and males. JCV types 1 and 4 were the most frequently detected, whereas JCV type 2 was rare, and type 3 was found only in one subject. The low frequency of JCV type 2 contrasts with the reported high frequency of this subtype in progressive multifocal leukoencephalopathy (PML), and supports its specific role in PML. The data indicate that JCV genotype epidemiology in Italy is quite different from that of other European countries; moreover, differences between the various Italian regions have been observed. An unexpected high frequency of a new variant of JCV type 4 with a stable point mutation (C --> G) at nucleotide 1851 was found. Furthermore, all the urinary strains had a TCR showing an archetypal organization.

Human neurotropic polyomavirus, JCV, and its role in carcinogenesis

A number of recent studies have reported the detection of the ubiquitous human polyomavirus, JC virus (JCV), in samples derived from several types of neural as well as non-neural human tumors. The human neurotropic JCV was first identified as the etiologic agent of the fatal demyelinating disease, progressive multifocal leukoencephalopathy, which usually occurs in individuals with defects in cell-mediated immunity, including AIDS. However, upon mounting evidence of the oncogenic potential of the viral regulatory protein, T-antigen, and JCV's oncogenecity in a broad range of animal models, studies were initiated to determine its potential involvement in human carcinogenesis. Initially, the most frequently observed tumors in rodent models, including medulloblastoma, astrocytoma, glioblastoma, and other neural-origin tumors were analysed. These studies were followed by analysis of non-neural tumors such as colorectal carcinomas. In a subset of each tumor type examined, JC viral genomic DNA sequences could be detected by PCR and confirmed by Southern blot hybridization or direct sequencing. In a smaller subset of the tumors, the expression of T-antigen was observed by immunohistochemical analysis. Owing to the established functions of T-antigen including its ability to interact with tumor suppressor proteins such as Rb and p53, and its ability to influence chromosomal stability, potential mechanisms of JCV T-antigen-mediated cellular dysregulation are discussed. Further, as increasing evidence suggests that T-antigen is not required for maintenance of a transformed phenotype, a hit-and-run model for T-antigen-induced transformation is proposed.

Oncogenic transformation by BK virus and association with human tumors

BK virus (BKV), a human polyomavirus closely related to JC virus and Simian Virus 40, is ubiquitous in human populations worldwide. After primary infection, BKV establishes a lifelong latent infection in many organs. BKV transforms rodent cells to the neoplastic phenotype and is highly oncogenic in rodents. This review considers the oncogenic potential of BKV in humans and its possible involvement in human tumors. BKV sequences and T antigen (Tag) are detected in several types of human neoplasms, although the viral load is generally low, with less than one copy of the viral genome per cell. The possible causative role of BKV in human oncogenesis rests on the ability of BKV Tag to inactivate the functions of tumor suppressor proteins p53 and pRB family as well as on its ability to induce chromosomal aberrations in human cells. A 'hit and run' mechanism and secretion of paracrine growth factors by BKV Tag-positive cells, recruiting into proliferation neighboring and distant cells, are discussed as possible BKV pathogenic elements in human oncogenesis.

Analysis of the excreted JC virus strains and their potential oral transmission

JC virus (JCV) particles have been detected in urban sewage of divergent geographical areas. In this study, the authors evaluate the genetic characteristics and the infective capabilities of JCV strains in relation to the potential oral transmission of JCV in the population. JCV strains excreted in urine and detected in sewage have been described as presenting archetypal structure of the regulatory region of the viral genome. The regulatory region of JCV viral particles detected in two urban sewage samples have been cloned and characterized. From a total of 40 clones tested, 39 presented archetypal-like regulatory regions, whereas 1 of the clones analyzed presented a tandem repeated structure. Archetypal strains present in the urine of a pregnant woman were able to infect SVG cells, producing infectious virions, as demonstrated by confirmative cell culture, electron microscopy, and in situ DNA hybridization. This is the first description of archetypal JCV productive infection of SVG cells. SVG cells were also successfully infected with Mad-4 JCV viral particles subjected to pH 3 for 1 h at 37 degrees C and to 10 microg/ml of trypsin in the same conditions. A decrease in the viral progeny production was observed when Mad-4 was subjected to acidic pH. Mad-4 did not produce any detectable infection in the enteric cell line CaCo-2. The oral route could represent a significant route of transmission of JCV infections because JCV virions have demonstrated relative resistance in the environment and to some of the conditions present in the gastrointestinal tract. The archetypal strains commonly detected in the environment may be implicated in the transmission of JCV among the population. Sporadic infection with strains presenting tandem repeated structures may have implications in pathogenicity.

Role of the environment in the transmission of JC virus

JC virus is etiologically associated with a fatal demyelinating disease known as PML. JCV produces persistent infections in the kidney and is excreted in the urine of healthy individuals and in the urine of PML patients. The characteristics of the JCV excreted in the environment have been studied by analyzing sewage samples from divergent geographical areas. The intergenic region of JCV strains detected in the sewage of Barcelona (Spain), Umeå (Sweden), Nancy (France), Pretoria (South Africa), Patras (Greece), Cairo (Egypt), Washington, D.C. (USA), and diverse areas of Northern India has been sequenced, and the phylogenetic analysis showed their relationships with JCV strains previously described in urine or clinical samples in these geographic areas. The JCV regulatory region of the JCV DNA detected in sewage presented archetypal or archetypal-like regulatory regions with the exception of one of the twenty clones obtained from a sewage sample of the area of Washington, D.C. that presented a tandem repeated structure. Infectivity studies showed that archetypal JCV present in the urine of a pregnant woman productively infected SVG cells. Also JC viral particles showed considerable stability in sewage at 20 degrees C and in front of treatments with acidic pH and trypsin. The high prevalence of JCV in urine and in sewage and the stability of the viral particles observed suggests that contaminated water, food, and fomites could be the vehicles of JCV transmission through the oral route. Virions partially degraded or noninfectious could be a source of JCV DNA and may represent an additional mechanism of entry of viral genes into cells.

An overview: Human polyomavirus JC virus and its associated disorders

JC virus (JCV) is a polyomavirus infecting greater than 80% of the human population early in life. Replication of this virus in oligodendrocytes and astrocytes results in the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in immunocompromised individuals, most notably acquired immunodeficiency syndrome (AIDS) patients. Moreover, recent studies have pointed to the association of JCV with a variety of brain tumors, including medulloblastoma. The JCV genome encodes for viral early protein, including large and small T antigens and the newly discovered isoform T', at the early phase of infection and the structural proteins VP1, VP2, and VP3 at the late stage of the lytic cycle. In addition, the late gene is responsible for the production of a small nonstructural protein, agnoprotein, whose function is not fully understood. Here, we have summarized some aspects of the JCV genome structure and function, and its associated diseases, including PML and brain tumors.

Members of the AP-1 family, c-Jun and c-Fos, functionally interact with JC virus early regulatory protein large T antigen

The activating protein 1 (AP-1) family of regulatory proteins is characterized as immediate-early inducible transcription factors which were shown to be activated by a variety of stress-related stimuli and to be involved in numerous biological processes, including cellular and viral gene expression, cell proliferation, differentiation, and tumorigenesis. We have recently demonstrated the involvement of the AP-1 family members c-Jun and c-Fos in transcriptional regulation of the human polyomavirus, JC virus (JCV), genome. Here, we further examined their role in JCV gene regulation and replication through their physical and functional interaction with JCV early regulatory protein large T antigen (T-Ag). Transfection and replication studies indicated that c-Jun and c-Fos can significantly diminish T-Ag-mediated JCV gene transcription and replication. Affinity chromatography and coimmunoprecipitation assays demonstrated that c-Jun and T-Ag physically interact with each other. Results from band shift assays showed that the binding efficiency of c-Jun to the AP-1 site was reduced in the presence of T-Ag. In addition, we have mapped, through the use of a series of deletion mutants, the regions of these proteins which are important for their interaction. While the c-Jun interaction domain of T-Ag is localized to the middle portion of the protein, the T-Ag interacting domain of c-Jun maps to its basic-DNA binding region. Results of transient-transfection assays with various c-Jun mutants and T-Ag expression constructs further confirm the specificity of the functional interaction between c-Jun and T-Ag. Taken together, these data demonstrate that immediate-early inducible transcription factors c-Jun and c-Fos physically and functionally interact with JCV major early regulatory protein large T-Ag and that this interaction modulates JCV transcription and replication in glial cells.

Epstein-Barr virus and microsatellite instability in gastric carcinogenesis

Little information is available concerning the relationship between transforming viruses and microsatellite instability (MSI). We evaluated Epstein-Barr virus (EBV) using in situ hybridization for EBV-encoded small RNAs and MSI using the polymerase chain reaction in surgically resected gastric cancer. The study subjects included 298 consecutive cases of solitary gastric carcinoma, 63 gastric carcinomas in young patients (</=30 years old), 64 cases of gastric cancer coexisting with gastric adenoma in a single lesion, 26 cases of gastric remnant cancer, and 98 carcinomas from 47 patients with synchronous multiple gastric carcinomas. There was no overlapping case among these subsets of gastric cancer. None of these 549 gastric carcinomas demonstrated both EBV positivity and MSI positivity. Furthermore, the EBV-positive and the MSI-positive cases showed a mutually negative association in all subsets of gastric cancer. 5.7% of consecutive solitary gastric carcinomas were EBV positive, and 9.7% were MSI positive. EBV was positive in 1.6% of gastric cancers coexisting with gastric adenoma, 12.7% of younger patients, 28.6% of gastric remnant cancer with previous gastrectomy for benign disease, and 14.5% of synchronous cancers without adenoma. MSI was found in 1.6% of younger patients, 18.8% of gastric cancers coexisting with gastric adenoma, 25% of gastric remnant cancer with previous gastrectomy for gastric cancer, and in 53.3% of synchronous gastric carcinomas having gastric adenoma remote from the cancer. In conclusion, the carcinogenic roles of EBV and MSI may be different in terms of each subset of gastric cancer. EBV and MSI may contribute to functionally equivalent pathways in gastric carcinogenesis.

JC virus: a biomarker for colorectal cancer?

Chromosomal instability (CIN) is present in most colorectal cancers, though the mechanism for these genetic aberrations is unclear. An explanation may lie in the possible link between JC virus (JCV) Mad-1 strain, found in colorectal cancers, and aneuploid neoplasia. It is proposed here to test the hypothesis that detection of JCV in colorectal cancer patients may serve as a clinically useful biomarker for the presence of colorectal tumors. This may be tested by looking for any correlation that may exist between JCV DNA, viral proteins, and anti-JCV anti-sera detected in samples of stool, blood, and urine obtained from patients with colorectal neoplasm compared with normal age-matched controls.

Detection of human polyomaviruses and papillomaviruses in prostatic tissue reveals the prostate as a habitat for multiple viral infections

BACKGROUND

To determine whether human polyomavirus (hPy) genomes are present in prostate tissues, we have carried out a polymerase chain reaction (PCR) screening in two sets of prostate samples, archival and fresh frozen, as well as performing in situ hybridization (ISH). The frozen prostate samples as well as the urine from the same patients were also screened for human papillomavirus (HPV) sequences.

METHODS

Highly sensitive nested-PCR assays were used. The detection of subpopulations of JC virus (JCV) -transcriptional control regions (TCRs) was also evaluated by Southern analysis and by direct DNA sequencing. An in situ hybridization technique was also used to detect JCV DNA in prostatic tissue.

RESULTS

The paraffin-embedded archival samples gave variable, unsatisfactory results. Results from the fresh frozen samples, however, were consistent and were frequently positive for JCV and less frequent for BK virus DNA. ISH confirmed the presence of JCV DNA in prostatic glandular epithelium. The TCR region of JCV from prostate tissue and urine from prostate cancer patients showed the presence of both archetypal and rearranged TCRs, including several new sequence variants. HPV DNA was also frequently detected and in some cases also mixed with hPy DNA from frozen tissue and urine.

CONCLUSION

The use of fresh frozen samples proved to be essential for consistent and reproducible detection of HPV and hPy viral DNAs. The presence of JCV DNA by ISH and the occurrence of a subpopulation of JCV TCR regions suggests that the prostate is a site for virus replication. The prostate is a complex habitat where mixed infections with oncogenic DNA viruses frequently occur and opens the discussion to the potential role of these viruses in the cancer of the prostate.