Human cytomegalovirus and human herpesvirus 6 genes that transform and transactivate

Human Cytomegalovirus Oncoprotection across Diverse Populations, Tumor Histologies, and Age Groups: The Relevance for Prospective Vaccinal Therapy

The oncogenicity of the human cytomegalovirus (CMV) is currently being widely debated. Most recently, mounting clinical evidence suggests an anti-cancer effect via CMV-induced T cell-mediated tumor destruction. However, the data were mostly obtained from single-center studies and in vitro experiments. Broad geographic coverage is required to offer a global perspective. Our study examined the correlation between country-specific CMV seroprevalence (across 73 countries) and the age-standardized incidence rate (of 34 invasive tumors). The populations studied were stratified according to decadal age periods as the immunologic effects of CMV seropositivity may depend upon age at initial infection. The International Agency for Research on Cancer of the World Health Organization (IARC WHO) database was used. The multivariate linear regression analysis revealed a worldwide inverse correlation between CMV seroprevalence and the incidences of 62.8% tumors. Notably, this inverse link persists for all cancers combined (Spearman's ρ = -0.732, p < 0.001; β = -0.482, p < 0.001, adjusted R2 = 0.737). An antithetical and significant correlation was also observed in particular age groups for the vast majority of tumors. Our results corroborate the conclusions of previous studies and indicate that this oncopreventive phenomenon holds true on a global scale. It applies to a wide spectrum of cancer histologies, additionally supporting the idea of a common underlying mechanism-CMV-stimulated T cell tumor targeting. Although these results further advance the notion of CMV-based therapies, in-depth investigation of host-virus interactions is still warranted.

[The incidence of infection in tumor and eye fluid system, and specific humoral immunity to herpes viruses in patients with uveal melanoma]

INTRODUCTION

Studies aimed at a direct research of human herpes viruses (HHVs) in the tumor material and eye media have not been carried out so far. Research goal to establish the frequency of detection HHVs DNA in the biomaterial of the eye and blood and to assess the specific humoral immunity to the causative agents of herpes virus infections in patients with uveal melanoma.

MATERIALS AND METHODS

38 patients with the uveal tract tumor were examined for the presence of DNA of HHV types 1 and 2 (HSV-1, 2), Cytomegalovirus (CMV), Varicella Zoster virus (VZV), EpsteinBarr virus (EBV) and herpes viruses 6 and 8 types (HHV-6, HHV-8) in tumor tissue, vitreous body, aqueous humour and blood plasma by real-time polymerase chain reaction; blood serum was studied by enzyme-linked immunosorbent assay (ELISA) for IgG and IgM antibodies to HHVs.

RESULTS

EBV DNA was present in tumor tissue in 20.6% of cases, in vitreous body in 4.2%, in blood plasma in 2.7%, and was not found in aqueous humor. Ig G antibodies to HSV-1, 2 and CMV were detected in 97.3% of cases, VZV 94.6%, HHV-6 32.4%, antibodies to HHV-8 were not detected. 20 patients (55.6%) had reactivation of chronic HSV-1, 2 infection, and 14 (38.9%) patients had reactivation of CMV infection. Markers of chronic EBV infection were found in all patients, its atypical reactivation was observed in 2 cases (5.4%).

CONCLUSION

Our findings suggest the possible participation of EBV in the oncogenesis of the uveal tract and emphasize the need for further in-depth study of this problem.

Cytomegalovirus infection may be oncoprotective against neoplasms of B-lymphocyte lineage: single-institution experience and survey of global evidence

Background

Although cytomegalovirus (CMV) is not considered tumorigenic, there is evidence for its oncomodulatory effects and association with hematological neoplasms. Conversely, a number of experimental and clinical studies suggest its putative anti-tumour effect. We investigated the potential connection between chronic CMV infection in patients with B-lymphocyte (B-cell) malignancies in a retrospective single-center study and extracted relevant data on CMV prevalences and the incidences of B-cell cancers the world over.

Methods

In the clinical single-center study, prevalence of chronic CMV infection was compared between patients with B-cell leukemia/lymphoma and the healthy controls. Also, global data on CMV seroprevalences and the corresponding country-specific incidences of B- lineage neoplasms worldwide were investigated for potential correlations.

Results

Significantly higher CMV seropositivity was observed in control subjects than in patients with B-cell malignancies (p = 0.035). Moreover, an unexpected seroepidemiological evidence of highly significant inverse relationship between country-specific CMV prevalence and the annual incidence of B-cell neoplasms was noted across the populations worldwide (ρ = −0.625, p < 0.001).

Conclusions

We try to draw attention to an unreported interplay between CMV infection and B-cell lymphomagenesis in adults. A large-scale survey across > 70 countries disclosed a link between CMV and B-cell neoplasms. Our evidence hints at an antagonistic effect of chronic CMV infection against B-lymphoproliferation.

Human cytomegalovirus hijacks host stress response fueling replication stress and genome instability

Viral infections enhance cancer risk and threaten host genome integrity. Although human cytomegalovirus (HCMV) proteins have been detected in a wide spectrum of human malignancies and HCMV infections have been implicated in tumorigenesis, the underlying mechanisms remain poorly understood. Here, we employed a range of experimental approaches, including single-molecule DNA fiber analysis, and showed that infection by any of the four commonly used HCMV strains: AD169, Towne, TB40E or VR1814 induced replication stress (RS), as documented by host-cell replication fork asymmetry and formation of 53BP1 foci. The HCMV-evoked RS triggered an ensuing host DNA damage response (DDR) and chromosomal instability in both permissive and non-permissive human cells, the latter being particularly relevant in the context of tumorigenesis, as such cells can survive and proliferate after HCMV infection. The viral major immediate early enhancer and promoter (MIEP) that controls expression of the viral genes IE72 (IE-1) and IE86 (IE-2), contains transcription-factor binding sites shared by promoters of cellular stress-response genes. We found that DNA damaging insults, including those relevant for cancer therapy, enhanced IE72/86 expression. Thus, MIEP has been evolutionary shaped to exploit host DDR. Ectopically expressed IE72 and IE86 also induced RS and increased genomic instability. Of clinical relevance, we show that undergoing standard-of-care genotoxic radio-chemotherapy in patients with HCMV-positive glioblastomas correlated with elevated HCMV protein markers after tumor recurrence. Collectively, these results are consistent with our proposed concept of HCMV hijacking transcription-factor binding sites shared with host stress-response genes. We present a model to explain the potential oncomodulatory effects of HCMV infections through enhanced replication stress, subverted DNA damage response and induced genomic instability.

Inherited chromosomally integrated HHV-6 possibly modulates human gene expression

Approximately, 1% of human population possesses a copy of human herpesvirus 6A and 6B (HHV-6A/B) in the genome. This viral element is referred to as inherited chromosomally integrated HHV-6A/B (iciHHV-6A/B) and is encoded in all of their cells. A recent study revealed that iciHHV-6A/B potentially increases the immune responses against HHV-6. However, it remains unclear whether iciHHV-6A/B affects human gene expression. Here, we perform global transcriptome analysis using the datasets obtained from various human tissues. We detected two and four individuals positive for iciHHV-6A and iciHHV-6B, respectively, and revealed that the transcriptional expression of iciHHV-6A/B was sporadic in the human body. Transcriptome analysis identified the human genes differentially expressed between iciHHV-6A/B-positive and -negative individuals. Particularly, the expression of some genes encoding immunoglobulins decreased in sigmoid colon of iciHHV-6A/B-positive individuals. Our findings suggest that iciHHV-6A/B may be associated with human health maintenance.

Cytomegalovirus is a tumor-associated virus: armed and dangerous

Human cytomegalovirus (HCMV) gene products are present in multiple human malignancies, often in specific association with tumor cells and tumor vasculature. Emerging evidence from human and mouse models of CMV infection in cancer indicate that CMV can transform epithelial cells, promote epithelial to mesenchymal transition (EMT) and mesenchymal to epithelial (MET) in tumor cells, promote tumor angiogenesis and proliferation and incapacitate the host anti-CMV immune response. This review will discuss the increasing role of HCMV in human cancer by demonstrating how HCMV is well suited for impacting major themes in oncogenesis including initiation, promotion, progression, metastasis and immune evasion. What emerges is a picture of an extremely versatile pathogen that may play a significant role in human cancer progression and death.

Detection of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) DNA in endocervical samples from a positive and negative HPV woman of Córdoba, Argentina

AIMS

The purpose of the present study was to elucidate the presence of human herpesvirus 6A (HHV-6A), HHV-6B and HHV-7 in samples of the uterine cervix through detection of viral DNA. We analysed normal tissues, samples with low-grade squamous intraepithelial lesions (LSILs) and high-grade squamous intraepithelial lesions (HSILs). We correlated the presence of HHV-6 and HHV-7 with the finding of human papillomavirus (HPV) in mucosal samples.

METHODS

Cervical samples were examined and grouped as follows: group 1 (n=29), normal cytology; group 2 (n=61), samples with LSIL; group 3 (n=35), samples with HSIL. Molecular biology examinations were performed in all samples to detect HHV-6, HHV-7 and HPV DNA and to typify HHV-6 species.

RESULTS

Group 1: normal cytology and HPV (-): HHV-6: 6.8% (2/29), HHV-7: 79.3% (23/29); group 2: LSIL and HPV (-): HHV-6: 93.1% (27/29), HHV-7: 96.5% (28/29); LSIL and HPV (+): HHV-6: 0% (0/32), HHV-7: 90.6% (29/32); group 3: HSIL and HPV (-): HHV-6: 20% (2/10), HHV-7: 70% (7/10); HSIL HPV (+): HHV-6: 12% (3/25), HHV-7: 68% (17/25). HHV-6A DNA was not detected in any samples.

CONCLUSIONS

(1) Both HHV-6 and HHV-7 infect the mucosal cells of the cervix with higher prevalence of HHV-7. (2) The higher prevalence of HHV-6 in LSIL HPV (-) samples compared with those with normal cytology indicates that it constitutes a possible risk factor for atypia production. (3) The presence of HHV-7 in all samples questions its role in the production of atypia. (4) The finding of HHV-6 and HHV-7 suggests that the cervical mucosa is a possible transmission pathway for these viruses.

DR7 encoded by human herpesvirus 6 promotes glioma development and progression

PURPOSE

We previously identified human herpesvirus 6 (HHV-6) infection in the pathogenesis of glioma. Direct repeat (DR)7, encoded by HHV-6, has been reported to possess malignant transforming activity and involved in Hodgkin's lymphoma carcinogenesis. Here, we aimed to determine the role of DR7 in the development and progression of glioma.

PATIENTS AND METHODS

A total of 27 glioma and 30 normal brain tissues were collected for detection of DR7. Glioma cell proliferation, colony formation, cell cycle, migration, invasion and angiogenesis were evaluated by Cell Counting Kit-8 (CCK-8), soft agar, propidium iodide staining, wound healing, Transwell and chick embryo chorioallantoic membrane assays, respectively. The potential mRNA targets of DR7 were determined using mRNA microarray and validated via Western blot and ELISA.

RESULTS

DR7 could be detected in the 13 glioma tissues with a positive rate of 48.15%, but only the 5 normal brain tissues with a lower positive rate of 16.7%. The two strains of cells isolated from glioma tissues were also found to express DR7. CCK-8 and soft agar assays showed enhanced proliferation and colony formation in the cells expressing DR7 which might be in relation to acceleration of the G1/S phase transition by DR7. Further analyses showed that DR7 could promote glioma cell migration, invasion and angiogenesis. Expression profiles identified hundreds of differentially expressed mRNAs, among which P53, extracellular matrix (ECM) fibronectin, integrin receptor ITGβ5 and specific inhibitors of MMPs, tissue inhibitor of MMPs (TIMP)-2 and TIMP-4, were downregulated, whereas ECM-degrading proteinase MMP-3, proinflammatory cytokines IL-1β, IL-6 and IL-8, were upregulated by DR7, respectively.

CONCLUSION

We observed existence of DR7 in the glioma tissues, and overexpression of DR7 could promote glioma cell development and progression, which might be through creating an inflammatory microenvironment and enhancing degradation of ECM.

Expression of Oncogenic Alleles Induces Multiple Blocks to Human Cytomegalovirus Infection

In contrast to many viruses, human cytomegalovirus (HCMV) is unable to productively infect most cancer-derived cell lines. The mechanisms of this restriction are unclear. To explore this issue, we tested whether defined oncogenic alleles, including the simian virus 40 (SV40) T antigen (TAg) and oncogenic H-Ras, inhibit HCMV infection. We found that expression of SV40 TAg blocks HCMV infection in human fibroblasts, whereas the replication of a related herpesvirus, herpes simplex virus 1 (HSV-1), was not impacted. The earliest restriction of HCMV infection involves a block of viral entry, as TAg expression prevented the nuclear delivery of viral DNA and pp65. Subsequently, we found that TAg expression reduces the abundance of platelet-derived growth factor receptor α (PDGFRα), a host protein important for HCMV entry. Viral entry into TAg-immortalized fibroblasts could largely be rescued by PDGFRα overexpression. Similarly, PDGFRα overexpression in HeLa cells markedly increased the levels of HCMV gene expression and DNA replication. However, the robust production of viral progeny was not restored by PDGFRα overexpression in either HeLa cells or TAg-immortalized fibroblasts, suggesting additional restrictions associated with transformation and TAg expression. In TAg-expressing fibroblasts, expression of the immediate early 2 (IE2) protein was not rescued to the same extent as that of the immediate early 1 (IE1) protein, suggesting that TAg expression impacts the accumulation of major immediate early (MIE) transcripts. Transduction of IE2 largely rescued HCMV gene expression in TAg-expressing fibroblasts but did not rescue the production of infectious virions. Collectively, our data indicate that oncogenic alleles induce multiple restrictions to HCMV replication.

IMPORTANCE

HCMV cannot replicate in most cancerous cells, yet the causes of this restriction are not clear. The mechanisms that restrict viral replication in cancerous cells represent viral vulnerabilities that can potentially be exploited therapeutically in other contexts. Here we found that SV40 T antigen-mediated transformation inhibits HCMV infection at multiple points in the viral life cycle, including through inhibition of proper viral entry, normal expression of immediate early genes, and viral DNA replication. Our results suggest that the SV40 T antigen could be a valuable tool to dissect cellular activities that are important for successful infection, thereby potentially informing novel antiviral development strategies. This is an important consideration, given that HCMV is a leading cause of birth defects and causes severe infection in immunocompromised individuals.

Cytomegalovirus and glioma: putting the cart before the horse

In 1908, Oluf Bang and Vilhelm Ellerman laid the foundation for theory of oncoviruses by demonstrating that the avian erythroblastosis (a form of chicken leukaemia) could be transmitted by cell-free extracts. Since then, it has been shown very convincingly that viruses can directly cause several human cancers by various mechanisms. Epidemiological data imply that viruses are the second most important risk factor for cancer development in humans, exceeded only by tobacco consumption. Although the ability of certain viruses (hepatitis B and C, human papillomavirus, etc) to cause cancer has been time tested and proven scientifically, there are several other potential viral candidates whose role in oncogenesis is more controversial. One such controversial scenario involves the role of cytomegalovirus (CMV) in malignant gliomas, the most common form of primary brain tumour. CMV first attracted attention about a decade ago when CMV gene products were found in glioma tissue but not in normal brain. Since this initial observation, several different groups have shown an oncomodulatory effect of CMV; however, direct association between CMV infection and incidence of glioma is lacking. In this review, we will evaluate the evidence, both preclinical and clinical, regarding the possible role of CMV in gliomagenesis and maintenance. We will also critically evaluate the rationale for using antiviral drugs in the treatment of patients with glioma.

Human herpes virus-6 as a cause of recurrent posterior uveitis in a HIV-positive patient

PURPOSE

To report a case of bilateral recurrent posterior uveitis caused by human herpes virus-6 (HHV-6) in a human immunodeficiency virus-positive individual.

METHODS

Comprehensive ophthalmic examination, including imaging with optical coherence tomography, fluorescein and indocyanine green angiography, and adequate laboratory tests were performed. A human immunodeficiency virus-positive patient without any AIDS defining condition, with a history of recurrent bilateral posterior uveitis referred to us with the diagnosis of retinal detachment.

RESULTS

Vitreous polymerase chain reaction detected an aberrant band for herpes viruses, which proved to be human herpes virus-6 by repeated polymerase chain reactions. Serum antibodies titer was positive for human herpes virus-6. The patient responded well to antiviral therapy with valacyclovir.

CONCLUSION

This is the first case of human herpes virus-6-related bilateral posterior uveitis in a human immunodeficiency virus-positive individual without clinical manifestations of AIDS.

Cytomegalovirus and brain tumor: epidemiology, biology and therapeutic aspects

PURPOSE OF REVIEW

First described in 2002, the presence and role of human cytomegalovirus (HCMV) infection in glioblastoma (GBM) has remained a controversial topic. New research indicates HCMV gene products likely promote GBM pathogenesis and that therapies aimed at HCMV might influence disease progression.

RECENT FINDINGS

Recently, investigators have begun to analyze HCMV genome and proteins present in GBM cells in vivo. Furthermore, the research has demonstrated that several HCMV gene products that have oncomodulatory properties are expressed in GBM and may be impacting tumor pathogenesis in vivo. These HCMV gene products modulate GBM proliferation, apoptosis, angiogenesis, invasion and immune evasion. A recent mouse model provides mechanistic information as to how CMV may promote gliomagenesis in the setting of tumor suppressor dysfunction and STAT3 signaling. In addition, clinical outcomes of GBM patients are associated with the degree of HCMV infection. Novel therapies aimed at direct antiviral and immunotherapy approaches to HCMV suggest that these modalities may impact the future treatment of this disease.

SUMMARY

A more precise understanding of the role of HCMV infection in gliomagenesis and GBM pathogenesis could reveal novel therapeutic and preventive strategies.

HHV-6 antigen and HHV-6 DNA expression in sporadic adenomatous polyps of the colon

BACKGROUND. Human herpesvirus-6B (HHV-6B) antigens are commonly found in the intestinal mucosa of patients with immunosuppression. In a series of immunocompetent patients with adenomatous, polyp HHV-6B antigen expression from mucosal biopsies was more intense than in biopsies taken from patients receiving immunosuppressive drugs because of kidney transplantation or inflammatory bowel disease. METHODS. HHV-6B and cytomegalovirus (CMV) antigen expression was determined from mucosal biopsy samples by immunohistochemistry. HHV-6-DNA content was studied in adenomatous polyps (seven tubular adenomas and one tubulovillous adenoma) taken from eight immunocompetent patients and in three mucosal biopsy samples taken from immunocompetent patients without adenomas using in situ hybridization (ISH) method. RESULTS. HHV-6B antigen expression on mucosal biopsies was strongly positive in five of eight patients with adenomas and negative in all patients without adenoma. CMV antigen expression on mucosal biopsies was faintly positive in three of adenoma patients. HHV-6 ISH was positive in seven of eight adenomatous polyps, most intense in the tubulovillous adenoma and negative in all three mucosal biopsies of patients without adenomas. CONCLUSION. Intensive HHV-6-DNA expression was found in adenomatous polyps of the colon. Further studies on involvement of HHV-6 in the development of gastrointestinal polyps are warranted.

The p53-microRNA-34a axis regulates cellular entry receptors for tumor-associated human herpes viruses

A growing number of reports indicate the frequent presence of DNA sequences and gene products of human cytomegalovirus in various tumors as compared to adjacent normal tissues, the brain tumors being studied most intensely. The mechanisms underlying the tropism of human cytomegalovirus to the tumor cells or to the cells of tumor origin, as well as the role of the host's genetic background in virus-associated oncogenesis are not well understood. It is also not clear why cytomegalovirus can be detected in many but not in all tumor specimens. Our in silico prediction results indicate that microRNA-34a may be involved in replication of some human DNA viruses by targeting and downregulating the genes encoding a diverse group of proteins, such as platelet-derived growth factor receptor-alpha, complement component receptor 2, herpes simplex virus entry mediators A, B, and C, and CD46. Notably, while their functions vary, these surface molecules have one feature in common: they serve as cellular entry receptors for human DNA viruses (cytomegalovirus, Epstein-Barr virus, human herpes virus 6, herpes simplex viruses 1 and 2, and adenoviruses) that are either proven or suspected to be linked with malignancies. MicroRNA-34a is strictly dependent on its transcriptional activator tumor suppressor protein p53, and both p53 and microRNA-34a are frequently mutated or downregulated in various cancers. We hypothesize that p53-microRNA-34a axis may alter susceptibility of cells to infection with some viruses that are detected in tumors and either proven or suspected to be associated with tumor initiation and progression.

Associations between human herpesvirus-6, human papillomavirus and cervical cancer

Cervical cancer (CxCa) is the second most common cancer among women globally. Human papillomavirus (HPV) infection is thought to be a necessary, but not sufficient, causal factor in CxCa development. Why some women are able to clear HPV infection with no adverse effects, whereas others develop cancer, remains unclear. HHV-6 has demonstrated transformative abilities and has been shown to be present in the genital tract. However, based on the current evidence, we cannot conclude that HHV-6 is a co-factor in HPV-associated carcinogenesis. Nonetheless, future research is warranted because of several crucial gaps in the literature.

Cytomegalovirus occurrence in chronic periodontitis and in carcinoma of the cervix: an exploratory study

AIMS

To explore the following in a group of carcinoma cervix patients with chronic periodontitis: The possible association of the Human Cytomegalovirus (HCMV) in chronic periodontitis and carcinoma of the cervix by examining the presence of HCMV (Human Cytomegalovirus) in saliva, Gingival Crevicular Fluid (G.C.F.) and in cervical biopsy samples and by comparing the clinical parameters among the Human Cytomegalovirus(HCMV) detected and the undetected sites. The possible association of chronic periodontitis and carcinoma of the cervix by assessing the common occurrence of HCMV in saliva, GCF and cervical biopsies.

MATERIAL AND METHODS

Sixteen female subjects who were aged 35 to 65 years, who were diagnosed with carcinoma of the cervix were selected. All the subjects underwent a clinical evaluation for their periodontal conditions. Cervical biopsies, saliva and GCF samples were obtained from all the participants and these were subjected to HCMV detection by using the nested PCR method.

RESULTS

HCMV has been detected in the cervical biopsies of 68.75 % patients, in the GCF samples of 75 % patients and in the saliva samples of 37.5 % patients. The clinical parameters i.e. probing pocket depth (P<0.008) and the clinical attachment level (P<0.026) were statistically significant in the GCF samples of the sites which were positive for HCMV as compared to those in the sites which were negative for HCMV. In 56% patients, HCMV was detected in both the cervical biopsies and the GCF samples. In 25% patients, HCMV was detected in both the cervical biopsies and the saliva samples.

CONCLUSION

The results are suggestive of a possible association of the HCMV occurrence in chronic periodontitis and a possible association of the HCMV occurrence and carcinoma of the cervix. An association between chronic periodontitis and carcinoma of the cervix cannot be elucidated with the available data, since the values are statistically insignificant. Hence, further research incorporating systemic inflammatory parameters would be necessary.

Chromosomally-integrated human herpesvirus 6 in familial glioma etiology

Human herpesvirus 6 (HHV-6) is a highly neurotropic beta-herpesvirus with demonstrated transformative properties. HHV-6 infection has been implicated in the etiologies of cancers, including lymphoma and leukemia; conditions with brain involvement, including epilepsy and encephalitis; and other disorders. HHV-6 is also the only human herpesvirus that has been proven to integrate into the chromosomes of a proportion (1-12%) of infected individuals. Because several traditional genetic association studies have failed to identify a variant that can account for the established relationship between family history and glioma risk, the possibility that chromosomally-integrated HHV-6 (CI-HHV-6), as a heritable factor, may explain a proportion of familial glioma cases warrants evaluation. To test this hypothesis, the prevalence of CI-HHV-6 in familial glioma cases and related and unrelated cancer-free control groups should be compared. Among glioma-affected families, the inheritance pattern of CI-HHV-6 could be evaluated by constructing pedigrees. If CI-HHV-6 is found to be associated with familial glioma risk, this knowledge could potentially lead to the future development of novel therapeutic and preventive approaches, including vaccines and immunotherapies targeted at the HHV-6 sequences.

Consensus on the role of human cytomegalovirus in glioblastoma

The human cytomegalovirus (HCMV) and glioma symposium was convened on April 17, 2011 in Washington, DC, and was attended by oncologists and virologists involved in studying the relationship between HCMV and gliomas. The purpose of the meeting was to reach a consensus on the role of HCMV in the pathology of gliomas and to clarify directions for future research. First, the group summarized data that describe how HCMV biology overlaps with the key pathways of cancer. Then, on the basis of published data and ongoing research, a consensus was reached that there is sufficient evidence to conclude that HCMV sequences and viral gene expression exist in most, if not all, malignant gliomas, that HCMV could modulate the malignant phenotype in glioblastomas by interacting with key signaling pathways; and that HCMV could serve as a novel target for a variety of therapeutic strategies. In summary, existing evidence supports an oncomodulatory role for HCMV in malignant gliomas, but future studies need to focus on determining the role of HCMV as a glioma-initiating event.

The roles of viruses in brain tumor initiation and oncomodulation

While some avian retroviruses have been shown to induce gliomas in animal models, human herpesviruses, specifically, the most extensively studied cytomegalovirus, and the much less studied roseolovirus HHV-6, and Herpes simplex viruses 1 and 2, currently attract more and more attention as possible contributing or initiating factors in the development of human brain tumors. The aim of this review is to summarize and highlight the most provoking findings indicating a potential causative link between brain tumors, specifically malignant gliomas, and viruses in the context of the concepts of viral oncomodulation and the tumor stem cell origin.

β-HHVs and HHV-8 in Lymphoproliferative Disorders

Similarly to Epstein-Barr virus (EBV), the human herpesvirus-8 (HHV-8) is a γ-herpesvirus, recently recognized to be associated with the occurrence of rare B cell lymphomas and atypical lymphoproliferations, especially in the human immunodeficiency virus (HIV) infected subjects. Moreover, the human herpesvirus-6 (HHV-6), a β-herpesvirus, has been shown to be implicated in some non-malignant lymph node proliferations, such as the Rosai Dorfman disease, and in a proportion of Hodgkin’s lymphoma cases. HHV-6 has a wide cellular tropism and it might play a role in the pathogenesis of a wide variety of human diseases, but given its ubiquity, disease associations are difficult to prove and its role in hematological malignancies is still controversial. The involvement of another β-herpesvirus, the human cytomegalovirus (HCMV), has not yet been proven in human cancer, even though recent findings have suggested its potential role in the development of CD4⁺ large granular lymphocyte (LGL) lymphocytosis. Here, we review the current knowledge on the pathogenetic role of HHV-8 and human β-herpesviruses in human lymphoproliferative disorders.

Congenital cytomegalovirus infection: molecular mechanisms mediating viral pathogenesis

Human cytomegalovirus (CMV) is responsible for approximately 40,000 congenital infections in the United States each year. Congenital CMV disease frequently produces serious neurodevelopmental disability, as well as vision impairment and sensorineural hearing loss. Development of a CMV vaccine is therefore considered to be a major public health priority. The mechanisms by which CMV injures the fetus are complex and likely include a combination of direct fetal injury induced by pathologic virally-encoded gene products, an inability of the maternal immune response to control infection, and the direct impact of infection on placental function. CMV encodes gene products that function, both at the RNA and the protein level, to interfere with many cellular processes. These include gene products that modify the cell cycle; interfere with apoptosis; induce an inflammatory response; mediate vascular injury; induce site-specific breakage of chromosomes; promote oncogenesis; dysregulate cellular proliferation; and facilitate evasion of host immune responses. This minireview summarizes current concepts regarding these aspects of the molecular virology of CMV and the potential pathogenic impact of viral gene expression on the developing fetus. Areas for potential development of novel therapeutic intervention are suggested for improving the outcome of this disabling congenital infection.

Salivary shedding of Epstein-Barr virus and cytomegalovirus in people infected or not by human immunodeficiency virus 1

The purpose of this study is to determine the frequency of EBV and CMV DNA detection in saliva of HIV infected and non-HIV individuals and their siblings. The study group comprised 240 individuals. Group 1 comprised of 40 HIV-infected patients, group 2 40 non-HIV individuals, group 3 two siblings for each patient from group 1 (n = 80), and group 4 two siblings for each individual from group 2 (n = 80). Non-stimulated whole saliva was collected, DNA was extracted, and amplification was performed using a nested PCR protocol. EBV and CMV DNA was detected in 7/40 (17.5%) and 5/40 (12.5%) individuals from group 1, 8/40 (20%) and 3/40 (7.5%) from group 2, 11/80 (13.8%) and 2/80 (2.5%) from group 3, and 8/80 (10%) and 1/80 (1.3%) from group 4, respectively. Five (71.4%) out of seven HIV/EBV coinfected individuals of group 1 had a relative also infected with EBV (OR = 11.25, CI [1.75-72.5], p = 0.011). Regarding group 2, among the eight non-HIV and EBV-infected individuals, three (37.5%) had a relative also positive to EBV (p = 0.320). No individual HIV/CMV coinfected had a relative CMV infected (p = 1.00). Also, only one non-HIV and CMV-infected individual had a relative also positive to CMV (p = 0.075). EBV and CMV DNA was detected mainly in those who had HIV viral load counts <400/mL (71%, p = 0.2 and 100%, p = 1, respectively) and those who had CD4 T cells counts between 200 and 400/mm(3) (57%, p = 0.544 and 60%, p = 0.249, respectively). HIV-infected individuals and healthy controls showed a similar frequency of viral DNA detection. EBV DNA was significantly amplified in saliva of household members of HIV/EBV coinfected individuals.

Tumor viruses and cancer biology: Modulating signaling pathways for therapeutic intervention

Tumor viruses have provided relatively simple genetic systems, which can be manipulated for understanding the molecular mechanisms of the cellular transformation process. A growing body of information in the tumor virology field provides several prospects for rationally targeted therapies. However, further research is needed to better understand the multiple mechanisms utilized by these viruses in cancer progression in order to develop therapeutic strategies. Initially viruses were believed to be associated with cancers as causative agents only in animals. It was almost half a century before the first human tumor virus, Epstein-Barr virus (EBV), was identified in 1964. Subsequently, several human tumor viruses have been identified including Kaposi sarcoma associated herpesvirus (KSHV), human Papillomaviruses (HPV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human T lymphotropic virus (HTLV-1) and recently identified Merkel cell Polyomavirus (MCPyV). Tumor viruses are sub-categorized as either DNA viruses, which include EBV, KSHV, HPV, HBV, and MCPyV, or RNA viruses such as HCV and HTLV-1. Tumor-viruses induce oncogenesis through manipulating an array of different cellular pathways. These viruses initiate a series of cellular events, which lead to immortalization and proliferation of the infected cells by disrupting the mitotic checkpoint upon infection of the host cell. This is often accomplished by functional inhibition or proteasomal degradation of many tumor suppressor proteins by virally encoded gene products. The virally infected cells can either be eliminated via cell-mediated apoptosis or persist in a state of chronic infection. Importantly, the chronic persistence of infection by tumor viruses can lead to oncogenesis. This review discusses the major human tumor associated viruses and their ability to modulate numerous cell signaling pathways, which can be targeted for potential therapeutic approaches.

Herpesviruses: hijacking the Ras signaling pathway

Cancer is the final result of the accumulation of several genetic alterations occurring in a cell. Several herpesviruses and especially gamma-herpesviruses have played an important role in Cancer Biology, contributing significantly to our comprehension of cell signaling and growth control pathways which lead to malignancy. Unlike other infectious agents, herpesviruses persist in the host by establishing a latent infection, so that they can reactivate periodically. Interestingly, some herpesviruses are able to either deliver or induce the expression of cellular oncogenes. Such alterations can result in the derailment of the normal cell cycle and ultimately shift the balance between continuous proliferation and programmed cell death. Herpesvirus infection employs key molecules of cellular signaling cascades mostly to enhance viral replication. However, most of these molecules are also involved in essential cellular functions, such as proliferation, cellular differentiation and migration, as well as in DNA repair mechanisms. Ras proteins are key molecules that regulate a wide range of cellular functions, including differentiation, proliferation and cell survival. A broad field of medical research is currently focused on elucidating the role of ras oncogenes in human tumor initiation as well as tumor progression and metastasis. Upon activation, Ras proteins employ several downstream effector molecules such as phosphatidylinositol 3-kinase (PI3-K) and Raf and Ral guanine nucleotide-dissociation stimulators (RALGDS) to regulate a cascade of events ranging from cell proliferation and survival to apoptosis and cellular death. In this review, we give an overview of the impact that herpesvirus infection has on the host-cell Ras signaling pathway, providing an outline of their interactions with the key cascade molecules with which they associate. Several of these interactions of viral proteins with member of the Ras signaling pathway may be crucial in determining herpesviruses' oncogenic potential or their oncomodulatory behavior. The questions that emerge concern the potential role of these molecules as therapeutic targets both for viral infections and cancer. Understanding the means by which viruses may cause oncogenesis would therefore provide a deeper knowledge of the overall oncogenic process.

Viral DNA detection and RAS mutations in actinic keratosis and nonmelanoma skin cancers

BACKGROUND

Actinic keratosis (AK) is a well-established precancerous skin lesion that has the potential to progress to squamous cell carcinoma (SCC). Basal cell carcinoma (BCC) is a locally aggressive slowly growing tumour that rarely metastasizes. A number of viruses have been proposed to play a role in the development of nonmelanoma skin cancers (NMSC), but the most plausible evidence to date suggests that cutaneous human papillomavirus (HPV) is the key instigating factor.

OBJECTIVES

To evaluate the prevalence of HPV, cytomegalovirus (CMV), herpes simplex virus (HSV) and Epstein-Barr virus (EBV) and investigate their relationship with the presence of RAS gene mutations in cutaneous lesions obtained from nonimmunosuppressed patients.

METHODS

HPV, CMV, HSV and EBV detection was performed using polymerase chain reaction (PCR) in skin biopsies (26 AK, 12 SCC and 15 BCC samples) that were collected from immunocompetent patients. The RAS mutation incidence was also investigated in all cutaneous lesions by use of PCR/restriction fragment length polymorphism and direct DNA sequencing.

RESULTS

Seventeen out of 53 (32%) skin lesions were found to be positive for HPV DNA. The highest incidences of HPV infection were five of 15 (33%) in BCC and four of 12 (33%) in SCC specimens. The HPV incidence was eight of 26 (31%) in AK and eight of 53 (15%) in normal skin tissue. Twelve out of 53 (23%) skin lesions were CMV-positive. The highest incidence of CMV infection was six of 15 (40%), observed in BCC specimens. The CMV incidence was two of 26 (8%) in AK and four of 12 (33%) in SCC. No normal skin biopsy was found to be positive for CMV. All cutaneous samples were negative for HSV and EBV DNA, as assessed by our PCR-based assays. Only three samples, one AK (4%), one BCC (6%) and one SCC (8%), were found to carry a G>T transversion at the second position of HRAS codon 12. Both HRAS mutant SCC and BCC biopsies were HPV- and CMV-positive, as well.

CONCLUSIONS

HPV DNA is detected in NMSC, AK and normal skin biopsies. Our results also indicate that CMV is involved in NMSC at higher levels than in premalignant lesions, whereas the virus was not detected in normal skin biopsies. HSV and EBV do not appear to be involved in the pathogenesis of cutaneous lesions. Moreover, we suggest that the HRAS codon 12 mutation is not a very common event in AK or NMSC. Finally, both viral infection and HRAS activation appear to represent independent factors in the aetiology of NMSC, samples of which were obtained from immunocompetent patients.

Detection of human herpesvirus-6 in adult central nervous system tumors: predominance of early and late viral antigens in glial tumors

The purpose is to determine the incidence of active and latent human herpesvirus-6 (HHV-6) infection in a large cohort of adult primary and recurrent CNS tumors. We screened a tissue microarray (TMA) containing more than 200 adult primary and recurrent CNS tumors with known clinical information for the presence of HHV-6 DNA by in situ hybridization (ISH) and protein by immunohistochemistry (IHC). One hundred six of 224 (47%) CNS tumors were positive for HHV-6 U57 Major Capsid Protein (MCP) gene by ISH compared to 0/25 non tumor control brain (P = 0.001). Fourteen of 30 (47%) tumors were HHV-6 MCP positive by nested PCR compared to 0/25 non-tumor brain controls (P = 0.001), revealing HHV-6 Variant A in 6 of 14 samples. HHV-6A/B early (p41) and late (gp116/64/54) antigens were detected by IHC in 66 of 277 (24%) (P = 0.003) and 84 of 282 (35%) (P = 0.002) tumors, respectively, suggesting active infection. HHV-6 p41 (P = 0.645) and gp116/64/54 (P = 0.198) antigen detection was independent of recurrent disease. Glial tumors were 3 times more positive by IHC compared to non glial tumors for both HHV-6 gp116/64/54 (P = 0.0002) and HHV-6 p41 (P = 0.004). Kaplan Meier survival analysis showed no effect of HHV-6 gp116/64/54 (P = 0.852) or HHV-6 p41 (P = 0.817) antigen detection on survival. HHV-6 early and late antigens are detected in adult primary and recurrent CNS tumors more frequently in glial tumors. We hypothesize that the glial-tropic features of HHV-6 may play an important modifying role in tumor biology that warrants further investigation.

Epstein-Barr virus nuclear antigen 3C targets p53 and modulates its transcriptional and apoptotic activities

The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3C with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCF(Skp2), cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53(-/-)) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.

The story of human cytomegalovirus and cancer: increasing evidence and open questions

Although human cytomegalovirus (HCMV) is generally not regarded to be an oncogenic virus, HCMV infection has been implicated in malignant diseases from different cancer entities. On the basis of our experimental findings, we developed the concept of "oncomodulation" to better explain the role of HCMV in cancer. Oncomodulation means that HCMV infects tumor cells and increases their malignancy. By this concept, HCMV was proposed to be a therapeutic target in a fraction of cancer patients. However, the clinical relevance of HCMV-induced oncomodulation remains to be clarified. One central question that has to be definitively answered is if HCMV establishes persistent virus replication in tumor cells or not. In our eyes, recent clinical findings from different groups in glioblastoma patients and especially the detection of a correlation between the numbers of HCMV-infected glioblastoma cells and tumor stage (malignancy) strongly increase the evidence that HCMV may exert oncomodulatory effects. Here, we summarize the currently available knowledge about the molecular mechanisms that may contribute to oncomodulation by HCMV as well as the clinical findings that suggest that a fraction of tumors from different entities is indeed infected with HCMV.

Androgen-dependent activation of human cytomegalovirus major immediate-early promoter in prostate cancer cells

BACKGROUND

Human cytomegalovirus (HCMV) major immediate early (MIE) promoter, which is involved in viral reactivation, is specifically activated by androgen in LNCaP prostate cancer cells.

METHODS

Androgen-dependent transcriptional activities of the HCMV MIE promoter were measured by transient transfection assay. Expression levels of genes related to protein kinase A (PKA)-signaling pathway was measured by RT-PCR.

RESULTS

Activation of the HCMV MIE promoter by androgen results from an increase in PKA activities. The expression level of PKA catalytic (C) subunit beta transcript variant 2 (PKA-C beta 2) was decreased by serum deprivation and was increased by R1881 treatment, in a pattern similar to changes of the HCMV MIE promoter activities. Furthermore the exogenous expression of PKA-C beta 2 strongly activated the HCMV MIE promoter, indicating that regulation of the PKA-C beta 2 expression might be a direct upstream factor in the HCMV MIE promoter regulation by androgen in LNCaP cells.

CONCLUSIONS

The data elucidated the mechanisms by which androgen activates PKA in androgen-dependent prostate cancer cells, resulting in activation of the HCMV MIE promoter. These results support the possibility that activation of the HCMV MIE promoter by androgen in the prostate could cause the productive infection, which might contribute to oncomodulation in prostate cancers.

Cytomegalovirus in colorectal cancer and idiopathic ulcerative colitis

Cytomegalovirus (CMV) is a genus in the family Herpesviridae that has been associated with gastrointestinal syndromes. In this work we looked for a possible association of CMV infection with colorectal cancer and ulcerative colitis (UC). Blood and enteric tissue samples of 14 patients with colorectal cancer and of 21 with UC were subjected to a nested-PCR that amplifies part of the gB gene of CMV and also to immunohistochemistry using a specific monoclonal antibody to IE 76 kDa protein of CMV. CMV was detected by nested-PCR in the blood and/or the enteric tissue of nine (64.3%) colorectal cancer and 16 (76.2%) ulcerative colitis patients. In the immunohistochemistry it was observed that 12 (12/21, 57.1%) positive enteric tissue samples of patients with UC and none from patients with colorectal cancer (0/14) were positive to CMV. The positivity of CMV infections in the UC patient group (12/21, 57.1%) showed by both techniques, was significantly higher (p = 0.015) than that observed for colorectal cancer patients (2/14, 14.3%). These results suggest an association of ulcerative colitis with CMV infection of the enteric tissue.

Detection and quantitative analysis of human herpesvirus in pilocytic astrocytoma

We investigated the hypothetical role of human herpesviruses (HHVs) in tumour formation of the cerebellum. Thirty-five samples of pilocytic astrocytoma and 10 control samples of cerebellum from patients who died of unrelated diseases were examined. Presence of the 8 known HHVs was first studied using specific real-time quantitative Polymerase Chain Reaction (qPCR) targeting viral DNA polymerase. HHV's DNA polymerase was found present in 20 samples (7 controls, 13 astrocytomas) and was absent in 25 samples (3 controls, 22 astrocytomas). DNA polymerase of Epstein-Barr Virus (EBV) was present in 16 samples, 7/10 controls (70%) and 9/35 astrocytomas (26%). HHV-1 and Varicella-Zoster virus were detected only twice and HHV-2, Cytomegalovirus, HHV-7 and HHV-8, only once. HHV-6 was not detected. In all cases, the gene copy numbers of DNA polymerase were low (<100/100 ng DNA). A second approach was to search for novel HHVs, using consensus-degenerated hybrid oligonucleotide primers (CODEHOP) PCR: no sequence indicative of a new HHV was detected. In summary, EBV was the most frequent HHV detected in pilocytic astrocytoma, but at very low levels. According to the actually accepted threshold the results suggest that EBV cannot be considered responsible for tumorigenesis of pilocytic astrocytoma.

Detection of human cytomegalovirus in different histological types of gliomas

The association between human cytomegalovirus (HCMV) infection and glioblastoma has been a source of debate in recent years because of conflicting laboratory reports concerning the presence of the virus in glioma tissue. HCMV is a ubiquitous herpesvirus that exhibits tropism for glial cells and has been shown to transform cells in vitro. Using sensitive immunohistochemical and in situ hybridization methods in 50 glioma samples, we detected HCMV antigen and DNA in 21/21 cases of glioblastoma, 9/12 cases of anaplastic gliomas and 14/17 cases of low-grade gliomas. Reactivity against the HCMV IE1 antigen (72 kDa) exhibited histology-specific patterns with more nuclear staining for anaplastic and low-grade gliomas, while GBMs showed nuclear and cytoplasmic staining that likely occurs with latent infection. Using IHC, the number of HCMV-positive cells in GBMs was 79% compared to 48% in lower grade tumors. Non-tumor areas of the tissue contained only four and 1% of HCMV-positive cells for GBMs and lower grade tumors, respectively. Hybridization to HCMV DNA in infected cells corresponded to patterns of immunoreactivity. Our findings support previous reports of the presence of HCMV infection in glioma tissues and advocate optimization of laboratory methods for the detection of active HCMV infections. This will allow for detection of low-level latent infections that may play an important role in the initiation and/or promotion of malignant gliomas.

Identification of novel viral interleukin-10 isoforms of human cytomegalovirus AD169

Two products of human cytomegalovirus (HCMV) UL111a gene have been previously identified to resemble human IL-10 (hIL-10). These viral IL-10s (vIL-10s) are able to induce signal transduction events and biological activities in a variety of cells. In this study, five novel vIL-10 transcripts were identified from HCMV AD169 infected MRC-5 cells. Some vIL-10 isoforms were post-translationally glycosylated, depending on the existence of a predicted N-linked glycosylation site. Similar to hIL-10, four of the vIL-10 isoforms apparently formed putative dimers. Among the different vIL-10 isoforms, vIL-10A significantly induced the phosphorylation of transcription factor STAT3 in THP-1 cells. All identified vIL-10 isoforms were able to form complexes with hIL-10, and enhanced hIL-10-induced STAT3 phosphorylation in different degrees. Identification of diverse forms of vIL-10 suggests that HCMV has developed a sophisticated mechanism to interfere with hIL-10 signaling pathway.

High prevalence of an active human cytomegalovirus infection in patients with colonic diverticulitis

BACKGROUND

Diverticulitis affects 10% of the western population and is characterized by microscopic inflammation of the colon. Increasing evidence suggests that human cytomegalovirus (HCMV) is an important pathogen in various inflammatory diseases. We hypothesized that HCMV contributes to the progression of diverticulitis, especially in immunocompromised patients in whom HCMV is a significant pathogen.

OBJECTIVES

To determine if HCMV is associated with diverticulitis and with an increased frequency of diverticulitis complications.

STUDY DESIGN

We examined the prevalence of an active HCMV infection in 23 patients with diverticulitis. Serum samples were analyzed for the presence of HCMV-IgG and HCMV-IgM antibodies in 11 of these patients. Immunohistochemistry was used for detection of HCMV early antigens in intestinal paraffin tissue sections obtained from the diverticulitis patients.

RESULTS

HCMV-early proteins could be detected in intestinal cells in 16/23 (69.6%) patients with diverticulitis. All of the 11 patients with serum samples were HCMV-IgG positive and 2 of these were also HCMV-IgM positive.

CONCLUSION

Active HCMV infection is frequently associated with diverticulitis and could contribute to the inflammatory process characteristic of diverticulitis.

Human cytomegalovirus-encoded chemokine receptor US28 promotes tumorigenesis

Human cytomegalovirus (HCMV) is a widely spread herpesvirus, suggested to play a role in tumor progression. US28, a chemokine receptor encoded by HCMV, binds a broad spectrum of chemokines and constitutively activates various pathways linked to proliferation. Our studies reveal that expression of US28 induces a proangiogenic and transformed phenotype by up-regulating the expression of vascular endothelial growth factor and enhancing cell growth and cell cycle progression. US28-expressing cells promote tumorigenesis when injected into nude mice. The G protein-uncoupled constitutively inactive mutant of US28, induces delayed and attenuated tumor formation, indicating the importance of constitutive receptor activity in the early onset of tumor development. Importantly, also in glioblastoma cells infected with the newly isolated clinical HCMV strain Titan, US28 was shown to be involved in the HCMV-induced angiogenic phenotype. Hence, the constitutively activated chemokine receptor US28 might act as a viral oncogene and enhance and/or promote HCMV-associated tumor progression.

Lack of association of herpesviruses with brain tumors

Gliomas are the most frequent primary brain tumors in humans. Many studies have been carried out on their etiology; however, the only confirmed risk factors are hereditary predisposing conditions and high dose of ionizing radiation. Recently, human cytomegalovirus (HCMV) gene products and nucleic acids were reported to be present in all of 27 glioma samples investigated in contrast to other brain tissues, and it was hypothesized that HCMV might play a role in glioma pathogenesis. To evaluate these findings, samples of 40 gliomas, 31 meningiomas, and 6 acoustic neurinomas (ACNs) were analyzed for the presence of HCMV macromolecules using polymerase chain reaction (PCR) and immunohistochemistry. Additionally, corresponding blood samples from 72 patients were analyzed for the presence of HCMV DNA to check for a possible contamination of tumor tissues with HCMV-infected blood cells. No HCMV DNA sequences were found, neither in brain tumor tissues nor in corresponding blood samples. Immunohistochemistry did not detect HCMV-specific proteins. Addressing a possible role of other herpesviruses as has been suggested in seroepidemiological studies, seroprevalence of antibodies to HCMV, herpes simplex virus (HSV), Epstein-Barr virus (EBV), and varicella-zoster virus (VZV) were determined by enzyme-linked immunosorbent assay (ELISA). Serological analyses of brain tumor patients showed no significant differences in the prevalences of antibodies to HCMV, HSV, EBV, or VZV compared to the general population. Thus, the data of the present study do not support the hypothesis of an association of herpesviruses with the development of primary brain tumors.

Lymphoma cell apoptosis in the liver induced by distant murine cytomegalovirus infection

Cytomegalovirus (CMV) poses a threat to the therapy of hematopoietic malignancies by hematopoietic stem cell transplantation, but efficient reconstitution of antiviral immunity prevents CMV organ disease. Tumor relapse originating from a minimal residual leukemia poses another threat. Although a combination of risk factors was supposed to enhance the incidence and severity of transplantation-associated disease, a murine model of a liver-adapted B-cell lymphoma has previously shown a survival benefit and tumor growth inhibition by nonlethal subcutaneous infection with murine CMV. Here we have investigated the underlying antitumoral mechanism. Virus replication proved to be required, since inactivated virions or the highly attenuated enhancerless mutant mCMV-DeltaMIEenh did not impact the lymphoma in the liver. Surprisingly, the dissemination-deficient mutant mCMV-DeltaM36 inhibited tumor growth, even though this virus fails to infect the liver. On the other hand, various strains of herpes simplex viruses consistently failed to control the lymphoma, even though they infect the liver. A quantitative analysis of the tumor growth kinetics identified a transient tumor remission by apoptosis as the antitumoral effector mechanism. Tumor cell colonies with cells surviving the CMV-induced "apoptotic crisis" lead to tumor relapse even in the presence of full-blown tissue infection. Serial transfer of surviving tumor cells did not indicate a selection of apoptosis-resistant genetic variants. NK cell activity of CD49b-expressing cells failed to control the lymphoma upon adoptive transfer. We propose the existence of an innate antitumoral mechanism that is triggered by CMV infection and involves an apoptotic signal effective at a distant site of tumor growth.

No CMV DNA in Guthrie cards from children who later developed ALL

An association of a viral infection in utero and development of acute lymphoblastic leukemia (ALL) has been suggested. Cytomegalovirus (CMV) has been reported as a leading agent of intrauterine infections resulting in some cases of congenital infections. The authors investigated the presence of prenatal CMV infection in children who later developed ALL. Guthrie cards were obtained from 48 children with ALL and 46 healthy children and were analyzed for the presence of CMV DNA by a real-time TaqMan PCR. CMV DNA was not detected in Guthrie cards from the children with ALL, from the control healthy children. The results show that prenatal CMV infection does not seem to be associated with later development of childhood ALL.

Modulation of p53 activity by IkappaBalpha: evidence suggesting a common phylogeny between NF-kappaB and p53 transcription factors

BACKGROUND

In this work we present evidence that the p53 tumor suppressor protein and NF-kappaB transcription factors could be related through common descent from a family of ancestral transcription factors regulating cellular proliferation and apoptosis. P53 is a homotetrameric transcription factor known to interact with the ankyrin protein 53BP2 (a fragment of the ASPP2 protein). NF-kappaB is also regulated by ankyrin proteins, the prototype of which is the IkappaB family. The DNA binding sequences of the two transcription factors are similar, sharing 8 out of 10 nucleotides. Interactions between the two proteins, both direct and indirect, have been noted previously and the two proteins play central roles in the control of proliferation and apoptosis.

RESULTS

Using previously published structure data, we noted a significant degree of structural alignment between p53 and NF-kappaB p65. We also determined that IkappaBalpha and p53 bind in vitro through a specific interaction in part involving the DNA binding region of p53, or a region proximal to it, and the amino terminus of IkappaBalpha independently or cooperatively with the ankyrin 3 domain of IkappaBalpha In cotransfection experiments, kappaBalpha could significantly inhibit the transcriptional activity of p53. Inhibition of p53-mediated transcription was increased by deletion of the ankyrin 2, 4, or 5 domains of IkappaBalpha Co-precipitation experiments using the stably transfected ankyrin 5 deletion mutant of kappaBalpha and endogenous wild-type p53 further support the hypothesis that p53 and IkappaBalpha can physically interact in vivo.

CONCLUSION

The aggregate results obtained using bacterially produced IkappaBalpha and p53 as well as reticulocyte lysate produced proteins suggest a correlation between in vitro co-precipitation in at least one of the systems and in vivo p53 inhibitory activity. These observations argue for a mechanism involving direct binding of IkappaBalpha to p53 in the inhibition of p53 transcriptional activity, analogous to the inhibition of NF-kappaB by kappaBalpha and p53 by 53BP2/ASPP2. These data furthermore suggest a role for ankyrin proteins in the regulation of p53 activity. Taken together, the NFkappaB and p53 proteins share similarities in structure, DNA binding sites and binding and regulation by ankyrin proteins in support of our hypothesis that the two proteins share common descent from an ancestral transcriptional factor.

Lack of association of cytomegalovirus with human brain tumors

Cytomegalovirus (CMV) is thought to possess oncogenic properties and has been linked with a number of human malignancies. CMV infection was recently described in association with malignant gliomas. The intent of the present study was to further investigate the reported association between CMV and malignant gliomas. Tissue from 22 brain tumors of various histologic types and grades, four normal brains, six breast carcinomas, six colon carcinomas, six lung carcinomas, and six sarcomas were evaluated for the presence of CMV by polymerase chain reaction (PCR), in situ hybridization, and immunohistochemical methods. None of the brain tumors or normal brain tissue tested demonstrated evidence of CMV pp65 or early nuclear proteins by immunohistochemistry. In addition, no CMV RNA or DNA was detected in these cases by in situ hybridization and PCR. None of the carcinomas or sarcomas evaluated were positive for CMV by immunohistochemistry, in situ hybridization, or PCR. The findings of the present study suggest that CMV is not significantly associated with brain tumors in humans.

Association of human herpesvirus type 6 DNA with human bladder cancer

We examined the presence of human herpesvirus type 6 (HHV6) DNA in a series of 74 bladder carcinomas from a Mediterranean population to elucidate their possible role as cofactor in the development of bladder cancer with or without associated human papillomavirus (HPV) infection. HHV-6 type B DNA was present in 5 men (6.8%) out of the 74 tumors investigated; two of them had associated HPV-16 DNA in the same specimen. In one case that had associated urothelial carcinoma in situ, both HHV-6B and HPV-16 DNA were present. In conclusion, the low incidence of HHV-6B in bladder cancer and the ubiquitous nature of HHV-6 infection are more consistent with a bystander role rather than cofactor in the oncogenesis of bladder cancer.

Role of p53, apoptosis, and cell proliferation in early stage Epstein-Barr virus positive and negative gastric carcinomas

AIMS

Mechanisms of Epstein-Barr virus (EBV) associated gastric tumour development are incompletely understood. The interrelations between EBV infection, apoptosis, cell proliferation, and the expression of the tumour suppressor gene p53 was investigated in 133 early stage gastric carcinomas.

METHODS

Tumour tissue was compared with paired non-tumour tissue. EBV encoded small RNAs (EBERs) determined EBV status. The apoptotic index (AI) was determined by morphology and verified biochemically. p53 and Ki-67 expression (cell proliferation) was assessed using immunohistochemistry.

RESULTS

EBV was detected in 14.3% of the cases. Cell proliferation did not differ significantly between EBV positive and negative cancers. However, within both these groups, the p53 positive and negative subsets differed significantly (EBV positive group: 76.8% and 55.3% were p53 positive or negative cancers, respectively; p<0.05; EBV negative group: 65.2% and 51.7% were p53 positive or negative, respectively; p<0.005). The numbers of p53 expressing EBV positive and negative cases were significantly different (57.9% and 82.5%, respectively; p<0.05). Compared with cell proliferation, apoptosis was significantly lower in EBV positive versus negative cancers (AI of 4.36 and 6.50, respectively; p<0.01). The p53 positive and negative subsets also differed significantly in AI (EBV positive group: AI of 5.13 and 3.30 for p53 positive and negative cancers, respectively; p<0.05: EBV negative group: AI of 6.84 and 4.90 for p53 positive and negative cancers, respectively; p<0.05).

CONCLUSIONS

These factors probably combine to promote development and progression of early stage gastric carcinomas and, at the same time, ensure the survival of EBV itself.

Update on human cytomegalovirus in destructive periodontal disease

AIM

Human cytomegalovirus (HCMV), a herpesvirus, is discussed in this review as it relates to destructive periodontal disease in humans.

RESULTS

HCMV genomic sequences, detected by polymerase chain reaction identification, occur with elevated frequency in severe adult periodontitis, localized and generalized aggressive (juvenile) periodontitis, Papillon-Lefèvre syndrome periodontitis, acute necrotizing ulcerative gingivitis, and periodontal abscesses.

DISCUSSION

Herpesviruses establish lifelong persistent infections. HCMV infection involves an asymptomatic latent phase interrupted by periods of recrudescence where viral replication and possibly clinical disease become manifest. HCMV reactivation is triggered by a number of immunosuppressive factors, some of which have been shown also to be risk factors/indicators of periodontitis. HCMV periodontal infection may cause release of tissue-destructive cytokines, overgrowth of pathogenic periodontal bacteria, and initiation of cytotoxic or immunopathologic events.

CONCLUSIONS

A growing body of data supports the concept that HCMV contributes to severe types of periodontal disease. HCMV infection of the periodontium may alter the immune control of resident microorganisms and be important in a multistage pathogenesis of periodontitis involving viral activation, periodontopathic bacteria, and host immune responses. Understanding the significance of HCMV and other herpesviruses in the development of periodontal disease may have important therapeutic implications. Vaccines against HCMV, which are in various stages of development, need to be evaluated for their ability to decrease the incidence of destructive periodontal disease.