Oncomodulation by human cytomegalovirus: evidence becomes stronger

Friend or Foe? Exploring the Role of Cytomegalovirus (HCMV) Infection in Head and Neck Tumors

Although not regarded as an oncogenic pathogen, the human cytomegalovirus (HCMV) has been associated with a wide array of malignancies. Conversely, a number of studies report on possible anti-tumor properties of the virus, apparently mediated via HCMV-galvanized T-cell tumor killing; these were recently being investigated in clinical trials for the purposes of anti-cancer treatment by means of dendritic cell vaccines and HCMV-specific cytotoxic T cells. In the present study, we have analyzed the relation between a complement of head-and-neck tumors and HCMV infection across 73 countries worldwide using Spearman correlation, univariate and multivariate regression analysis. Intriguingly, HCMV was found to be pro-oncogenic in patients with nasopharyngeal carcinoma; contrarywise, the virus manifested an inverse (i.e., anti-tumor) association with the tumors of the lip/oral region and the salivary glands. Although this putative protective effect was noted initially for thyroid neoplasia and hypopharyngeal tumors as well, after multivariate regression analysis the connection did not hold. There was no association between laryngeal cancer and HCMV infection. It would appear that, depending on the tissue, HCMV may exert both protective and oncogenic effects. The globally observed protective feature of the virus could potentially be utilized in future therapeutic approaches for salivary tumors and neoplasia in the lip/oral region. As correlation does not necessarily imply causation, more in-depth molecular analyses from comprehensive clinical studies are warranted to substantiate our findings.

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.

Higher Human Cytomegalovirus (HCMV) Specific IgG Antibody Levels in Plasma Samples from Patients with Metastatic Brain Tumors Are Associated with Longer Survival

Background: Human cytomegalovirus (HCMV) has been detected in tissue samples from patients with glioblastoma but little is known about the systemic immunological response to HCMV in these patients. Objectives: To investigate the presence and clinical significance of HCMV antibodies levels in plasma samples obtained from patients with brain tumors. Materials and Methods: HCMV-specific IgG and IgM antibody levels were determined in 59 plasma samples collected from brain tumor patients included in a prospective study and in 114 healthy individuals. We examined if the levels of HCMV specific antibodies varied in patients with different brain tumor diagnoses compared to healthy individuals, and if antibody levels were predictive for survival time. Results: HCMV specific IgG antibodies were detected by ELISA in 80% and 89% of patients with GBM and astrocytoma grades II-III, respectively, in all samples (100%) from patients with secondary GBM and brain metastases, as well as in 80% of healthy donors (n = 114). All plasma samples were negative for HCMV-IgM. Patients with brain metastases who had higher plasma HCMV-IgG titers had longer survival times (p = 0.03). Conclusions: HCMV specific IgG titers were higher among all brain tumor patient groups compared with healthy donors, except for patients with secondary GBM. Higher HCMV specific IgG levels in patients with brain metastases but not in patients with primary brain tumors were associated with prolonged survival time.

Cytomegalovirus and Glioblastoma: A Review of the Biological Associations and Therapeutic Strategies

Glioblastoma is the most common and aggressive malignancy in the adult central nervous system. Cytomegalovirus (CMV) plays a crucial role in the pathogenesis and treatment of glioblastoma. We reviewed the epidemiology of CMV in gliomas, the mechanism of CMV-related carcinogenesis, and its therapeutic strategies, offering further clinical practice insights. To date, the CMV infection rate in glioblastoma is controversial, while mounting studies have suggested a high infection rate. The carcinogenesis mechanism of CMV has been investigated in relation to various aspects, including oncomodulation, oncogenic features, tumor microenvironment regulation, epithelial–mesenchymal transition, and overall immune system regulation. In clinical practice, the incidence of CMV-associated encephalopathy is high, and CMV-targeting treatment bears both anti-CMV and anti-tumor effects. As the major anti-CMV treatment, valganciclovir has demonstrated a promising survival benefit in both newly diagnosed and recurrent glioblastoma as an adjuvant therapy, regardless of surgery and the MGMT promoter methylation state. Immunotherapy, including DC vaccines and adoptive CMV-specific T cells, is also under investigation, and preliminary results have been promising. There are still questions regarding the significance of CMV infection and the carcinogenic mechanism of CMV. Meanwhile, studies have demonstrated the clinical benefits of anti-CMV therapy in glioblastoma. Therefore, anti-CMV therapies are worthy of further recognition and investigation.

Human cytomegalovirus alters immune cell profile with potential implications for patient survival in head and neck cancer

Cytomegalovirus (CMV) is a highly prevalent human herpes virus that exerts a strong influence on immune repertoire which may influence cancer risk. We have tested whether CMV immunoglobulin G (IgG) serostatus is associated with immune cell proportions (n = 132 population controls), human papillomavirus (HPV) co-infection and head and neck cancer risk (n = 184 cancer cases and 188 controls) and patient survival. CMV status was not associated with the proportion of Natural Killer cells, B cells or the neutrophil-to-lymphocyte ratio. However, CD8+ T cells increased with increasing categories of IgG titers (P =1.7 × 10-10), and titers were inversely associated with the CD4:CD8 ratio (P = 5.6 × 10-5). Despite these differences in T cell proportions, CMV was not associated with HPV16 co-infection. CMV seropositivity was similar in cases (52%) and controls (47%) and was not associated with patient survival (hazard ratio [HR] 1.14, 95% confidence interval [CI]: 0.70 to 1.86). However, those patients with the highest titers had the worst survival (HR 1.91, 95% CI: 1.13 to 3.23). Tumor-based data from The Cancer Genome Atlas demonstrated that the presence of CMV transcripts was associated with worse patient survival (HR 1.79, 95% CI: 0.96 to 2.78). These findings confirm that a history of CMV infection alters T cell proportions, but this does not translate to HPV16 co-infection or head and neck cancer risk. Our data suggest that high titers and active CMV virus in the tumor environment may confer worse survival.

Medulloblastoma drugs in development: Current leads, trials and drawbacks

Medulloblastoma (MB) is the most common malignant brain tumor in children. Current treatment for MB includes surgical resection, radiotherapy and chemotherapy. Despite significant progress in its management, a portion of children relapse and tumor recurrence carries a poor prognosis. Based on their molecular and clinical characteristics, MB patients are clinically classified into four groups: Wnt, Hh, Group 3, and Group 4. With our increased understanding of relevant molecular pathways disrupted in MB, the development of targeted therapies for MB has also increased. Targeted drugs have shown unique privileges over traditional cytotoxic therapies in balancing efficacy and toxicity, with many of them approved and widely used clinically. The aim of this review is to present the recent progress on targeted chemotherapies for the treatment of all classes of MB.

The emerging role of human cytomegalovirus infection in human carcinogenesis: a review of current evidence and potential therapeutic implications

It is well-established that infections with viruses harboring oncogenic potential increase the cancer risk. Virus induced oncogenic processes are influenced by a complex and unique combination of host and environmental risk factors that are currently not fully understood. Many of the oncogenic viruses exhibit a prolonged, asymptomatic latency after a primary infection, and cause cancer in only a minority of carriers. From an epidemiologic point of view, it is therefore difficult to determine their role in cancer development. However, recent evidence suggests a neoplastic potential of one additional ubiquitous virus; human Cytomegalovirus (HCMV). Emerging data presents HCMV as a plausible cancer-causing virus by demonstrating its presence in >90% of common tumor types, while being absent in normal tissue surrounding the tumor. HCMV targets many cell types in tumor tissues, and can cause all the ten proposed hallmarks of cancer. This virus exhibits cellular tumor-promoting and immune-evasive strategies, hijacks proangiogenic and anti-apoptotic mechanisms and induces immunosuppressive effects in the tumor micro-environment. Recognizing new cancer-causing mechanisms may increase the therapeutic potential and prophylactic options for virus associated cancer forms. Such approaches could limit viral spread, and promote anti-viral and immune controlling strategies if given as add on to standard therapy to potentially improve the prognosis of cancer patients. This review will focus on HCMV-related onco-viral mechanisms and the potential of HCMV as a new therapeutic target in HCMV positive cancer forms.

Protein and DNA evidences of HCMV infection in primary breast cancer tissues and metastatic sentinel lymph nodes

BACKGROUND AND OBJECTIVE

Breast cancer is the leading cause of death in women worldwide. There are evidences that human cytomegalovirus (HCMV) infection is associated with several malignant tumors. This study aims to investigate the infection of human cytomegalovirus (HCMV) in a large sample of breast cancer patients, and conduct a correlation analysis of clinical and pathological factors, to provide evidence for whether HCMV infection is associated with breast cancer development, progression and metastasis.

MATERIALS AND METHODS

A total of 438 tissue samples (including breast cancer tissue, paracancerous tissue and sentinel lymph node [SLN] tissue) obtained from 146 patients who were diagnosed with breast cancer and intraoperatively underwent unilateral axillary SLN biopsy at the Affiliated Hospital of Qingdao University from June 2013 to June 2014 were included into this study. These tissue samples were divided into two groups: SLN positive group and SLN negative group. The clinical information is collated and numbered. Normal breast tissues of 40 patients with cyclomastopathy were taken as controls. The expressions of HCMV immediate-early (IE) and late antigen (LA) proteins of breast cancer tissues, paracancerous tissues, SLN tissues and normal breast tissues were analyzed by immunohistochemistry, and HCMV infection of the samples was graded according to the percentage of the positive cells, and HCMV IE2 mRNA expression was detected by reverse transcription polymerase chain reaction. The clinical data were collated and statistically analyzed.

RESULTS

HCMV IE and LA proteins were highly expressed in all breast cancer tissue samples. IE proteins were detected in 47.9% (70/146) of paracancerous tissue samples, and LA proteins were detected in 53.4% (78/146) of paracancerous tissue samples. IE and LA proteins were expressed in 92.6% of metastatic SLN samples (62/68) and in most of the tumor cells. Inflammatory cells in 60% (42/70) of non-metastatic samples were positive for HCMV. HCMV DNA was present in 100% of breast cancer tissue samples, 50% of paracancerous tissue samples, and 91% of metastatic SLN samples; but this was not present in HCMV negative and non-metastatic SLN samples. Differences in HCMV infection, and estrogen receptor-α, progesterone receptor, Elston classification, Ki67 percentage, Her-2 and Luminal type and other clinical indicators were not statistically significant.

CONCLUSION

HCMV infection is common in breast cancer tissues, paracancerous tissues and SLN tissues. The severity of HCMV infection varied markedly with tissue type. HCMV infection might be associated with metastasis and invasion of breast cancer. The expression of HCMV IE2 was associated to breast cancer and lymph node metastasis. The expression level of estrogen receptor-α was related to HCMV infection.

US28: HCMV's Swiss Army Knife

US28 is one of four G protein coupled receptors (GPCRs) encoded by human cytomegalovirus (HCMV). The US28 protein (pUS28) is a potent signaling molecule that alters a variety of cellular pathways that ultimately alter the host cell environment. This viral GPCR is expressed not only in the context of lytic replication but also during viral latency, highlighting its multifunctional properties. pUS28 is a functional GPCR, and its manipulation of multiple signaling pathways likely impacts HCMV pathogenesis. Herein, we will discuss the impact of pUS28 on both lytic and latent infection, pUS28-mediated signaling and its downstream consequences, and the influence this viral GPCR may have on disease states, including cardiovascular disease and cancer. We will also discuss the potential for and progress towards exploiting pUS28 as a novel therapeutic to combat HCMV.

Lack of cytomegalovirus detection in human glioma

Gliomas are the most common brain tumors and include a variety of histologic types and grades of malignancy. They arise from glial cells and represent approximately 70% of the primary brain tumors. According to the criteria of the World Health Organization (WHO), the majority of gliomas can be classified into four grades of malignancy (I-IV). Virus infection, especially by DNA viruses and retroviruses, which may cause insertion of viral DNA sequences into the host genome, often triggers the host defense mechanisms. Particularly, the DNA methylation machinery can be activated to cause the methylation of foreign movable viral sequences and, therefore, silence viral gene expression. Several studies have shown the presence of Human Cytomegalovirus (HCMV) in glioblastoma, suggesting that the virus may participate in tumor pathogenesis. But this relationship is controversial because many other studies did not detect HCMV in these tumors. This study aims to detect the presence of HCMV in several samples of human glioma (94 formalin-fixed, paraffin-embedded samples and 28 snap-frozen samples) by different sensitive techniques. We have been unable to detect HCMV DNA and proteins in glioma samples. Therefore, arguments used so far to conclude that HCMV is an oncomodulator virus in gliomas must be, in our view, seriously reconsidered.

Cytomegalovirus driven immunosenescence-An immune phenotype with or without clinical impact?

The continuous emerging increase in life span has led to vulnerability to a number of different diseases in the elderly. Some of these risks may be attributed to specific changes in the immune system referred to as immunoscenescence. This term aims to describe decreased immune functions among elderly individuals, and is characterized to be harmful age-associated changes in the immune system that lead to its gradual immune dysfunction. An impaired function of the immune system may increase susceptibility to various diseases in the elderly population such as infections, cardiovascular diseases and cancer. Although it is unclear how this immune phenotype develops, emerging evidence suggest that it may reflect an exhaustion of the immune system, possibly caused by one or several chronic infections. The main candidate is human cytomegalovirus (CMV), which can induce immune dysfunctions observed in immunoscenescence. Although the immune system is currently considered to be exhausted in CMV positive elderly individuals, it is not known whether such dysfunction of the immune system is a main reason for increased susceptibility to other diseases, or if direct effects of the virus in disease pathogenesis reflect the increased vulnerability to them. These aspects will be discussed in this review.

Ganciclovir concentrations in the cerebral extracellular space after valganciclovir treatment; a case study

Nearly all glioblastomas (GBMs), brain tumours with very poor prognosis, are infected with human cytomegalovirus (CMV). The anti-CMV drug valganciclovir (VGCV) has shown promise as a treatment option for patients with GBM, but its penetration into the central nervous system (CNS) is unknown. Here we describe a patient with GMB receiving VGCV in whom an intracerebral microdialysis catheter was implanted and ganciclovir (GCV) concentrations in brain extracellular fluid (BECF) and serum were monitored. GCV was rapidly absorbed. Cmax values (at 3 h) in serum and BECF were 19.6 and 10.2 µmol/L, T½ values were 3.2 and 4.5 h, and plasma and BECF AUC0-∞ values were 90.7 and 75.9 µmol h/L, respectively. Thus, VGCV treatment results in significant intracerebral levels of GCV that may be sufficient for therapeutic effects. Further studies of this drug in patients with GBM are warranted.

Serological and viraemic status of human cytomegalovirus infection in patients with colorectal cancer is not correlated with viral replication and transcription in tumours

Colorectal cancer (CRC) is amongst the leading causes of cancer-related mortality worldwide. Emerging evidence suggests that human cytomegalovirus (HCMV) exists in the tumour tissue of CRC and is associated with disease outcome. To study whether tumoral HCMV is related to viral reactivation in blood, tumour specimens and pre- and post-operative blood samples from CRC patients were collected prospectively. PCR and quantitative PCR were performed to detect HCMV DNA. HCMV IgG and IgM antibodies were measured using a microparticle enzyme immunoassay. Transcription of a spliced HCMV UL73 gene transcript was analysed by quantitative reverse transcription PCR. HCMV was detected in 42.2% (35/83) of the tumour samples, with a low median viral load (30.08, range 2.33-5704 copies per 500  ng genomic DNA). The vast majority (80/81, 98.8%) of the CRC patients were seropositive for HCMV IgG. HCMV DNA was positive in 11.3% (22/194) of the pre-operative and 8.9% (15/168) of the post-operative blood samples. However, presence of HCMV and its viral load in tumours were not associated with the detection or viral loads in blood samples. About 26.67% (8/30) of the HCMV-positive tumours with available RNA had detectable viral UL73 transcripts, whilst none of the blood samples were positive for viral RNA (P < 0.0001). Therefore, presence of HCMV in tumours does not correlate with the serological or viraemic status of CRC patients. Active viral gene transcription occurred in the tumour but not in the blood of CRC patients. HCMV reactivation in CRC patients is possibly due to virus-cancer interactions in the CRC tumour microenvironment.

Discordant humoral and cellular immune responses to Cytomegalovirus (CMV) in glioblastoma patients whose tumors are positive for CMV

Background. Glioblastoma (GBM) is the most common malignant brain tumor in adults and is nearly always fatal. Emerging evidence suggests that human Cytomegalovirus (HCMV) is present in 90-100% of GBMs and that add-on antiviral treatment for HCMV show promise to improve survival. Methods. In a randomized, placebo-controlled trial of valganciclovir in 42 GBM patients, blood samples were collected for analyses of HCMV DNA, RNA, reactivity against HCMV peptides, IgG, and IgM at baseline and at 3, 12, and 24 weeks of treatment. Results. All 42 tumors were positive for HCMV protein. All patients examined had at least one blood sample positive for HCMV DNA, 63% were HCMV RNA positive, and 21% were IgM positive. However, 29% of GBM patients were IgG negative for HCMV. Five of these samples were positive in an enzyme-linked immunosorbent assay (ELISA) that used antigens derived from a clinical isolate. Blood T cells from 11 of 13 (85%) HCMV IgG-negative GBM patients reacted against HCMV peptides. Valganciclovir did not affect IgG titers, DNA, or RNA levels of the HCMV immediate early (HCMV IE) gene in blood. Conclusion. In GBM patients, HCMV activity is higher than in healthy controls and serology is a poor test to define previous or active HCMV infection in these patients.

Human cytomegalovirus antigens in malignant gliomas as targets for adoptive cellular therapy

Malignant gliomas are the most common primary brain tumor in adults, with over 12,000 new cases diagnosed in the United States each year. Over the last decade, investigators have reliably identified human cytomegalovirus (HCMV) proteins, nucleic acids, and virions in most high-grade gliomas, including glioblastoma (GBM). This discovery is significant because HCMV gene products can be targeted by immune-based therapies. In this review, we describe the current level of understanding regarding the presence and role in pathogenesis of HCMV in GBM. We describe our success detecting and expanding HCMV-specific cytotoxic T lymphocytes to kill GBM cells and explain how these cells can be used as a platform for enhanced cellular therapies. We discuss alternative approaches that capitalize on HCMV infection to treat patients with HCMV-positive tumors. Adoptive cellular therapy for HCMV-positive GBM has been tried in a small number of patients with some benefit, but we reason why, to date, these approaches generally fail to generate long-term remission or cure. We conjecture how cellular therapy for GBM can be improved and describe the barriers that must be overcome to cure these patients.

Human cytomegalovirus tegument protein pp65 is detected in all intra- and extra-axial brain tumours independent of the tumour type or grade

Human cytomegalovirus (HCMV) has been indicated being a significant oncomodulator. Recent reports have suggested that an antiviral treatment alters the outcome of a glioblastoma. We analysed the performance of commercial HCMV-antibodies applying the immunohistochemical (IHC) methods on brain sample obtained from a subject with a verified HCMV infection, on samples obtained from 14 control subjects, and on a tissue microarray block containing cores of various brain tumours. Based on these trials, we selected the best performing antibody and analysed a cohort of 417 extra- and intra-axial brain tumours such as gliomas, medulloblastomas, primary diffuse large B-cell lymphomas, and meningiomas. HCMV protein pp65 immunoreactivity was observed in all types of tumours analysed, and the IHC expression did not depend on the patient's age, gender, tumour type, or grade. The labelling pattern observed in the tumours differed from the labelling pattern observed in the tissue with an active HCMV infection. The HCMV protein was expressed in up to 90% of all the tumours investigated. Our results are in accordance with previous reports regarding the HCMV protein expression in glioblastomas and medulloblastomas. In addition, the HCMV protein expression was seen in primary brain lymphomas, low-grade gliomas, and in meningiomas. Our results indicate that the HCMV protein pp65 expression is common in intra- and extra-axial brain tumours. Thus, the assessment of the HCMV expression in tumours of various origins and pathologically altered tissue in conditions such as inflammation, infection, and even degeneration should certainly be facilitated.

Gene expression profiles of various cytokines in mesenchymal stem cells derived from umbilical cord tissue and bone marrow following infection with human cytomegalovirus

Mesenchymal stem cells (MSCs) have both multi-lineage differentiation potential and immunosuppressive properties, making them ideal candidates for regenerative medicine. However, their immunosuppressive properties potentially increase the risk of cancer progression and opportunistic infections. In this study, MSCs isolated from human umbilical cord blood (UCMSCs) and adult bone marrow (BMMSCs) were infected with human cytomegalovirus (HCMV). Cytopathic changes were observed 10 days post infection. PCR products amplified from genomic DNA and cDNA were used to confirm the HCMV infection of the UCMSCs and BMMSCs. Real-time PCR was conducted to quantify the expression of immunomodulatory molecules, including cytokines, chemokines, growth factors, adhesion molecules and cancer-related genes. Our results indicate high upregulation of the majority of these molecules, including many growth factors, tumor necrosis factor alpha, interleukin-8, interleukin-6 and interferon gamma. Adhesion molecules (VCAM-1, TCAM-1 and selectin-E) were downregulated in the infected UCMSCs and BMMSCs. Antibody chip array evaluation of cell culture media indicated that the growth factor secretion by UCMSCs and BMMSCs was greatly influenced (p < 0.001) by HCMV. The stimulation of MSCs with HCMV led to the activation of downstream signaling pathways, including pSTAT3 and Wnt2. Our results show that HCMV can significantly alter the functions of both UCMSCs and BMMSCs, although not in the same way or to the same extent. In both cases, there was an increase in the expression of proangiogenic factors in the microenvironment following HMCV infection. The discrepancy between the two cell types may be explained by their different developmental origin, although further analysis is necessary. Future studies should decipher the underlying mechanism by which HCMV controls MSCs, which may lead to the development of new therapeutic treatments.

High prevalence of human cytomegalovirus proteins and nucleic acids in primary breast cancer and metastatic sentinel lymph nodes

Background

Breast cancer is a leading cause of death among women worldwide. Increasing evidence implies that human cytomegalovirus (HCMV) infection is associated with several malignancies. We aimed to examine whether HCMV is present in breast cancer and sentinel lymph node (SLN) metastases.

Materials and Methods

Formalin-fixed paraffin-embedded tissue specimens from breast cancer and paired sentinel lymph node (SLN) samples were obtained from patients with (n = 35) and without SLN metastasis (n = 38). HCMV immediate early (IE) and late (LA) proteins were detected using a sensitive immunohistochemistry (IHC) technique and HCMV DNA by real-time PCR.

Results

HCMV IE and LA proteins were abundantly expressed in 100% of breast cancer specimens. In SLN specimens, 94% of samples with metastases (n = 34) were positive for HCMV IE and LA proteins, mostly confined to neoplastic cells while some inflammatory cells were HCMV positive in 60% of lymph nodes without metastases (n = 35). The presence of HCMV DNA was confirmed in 12/12 (100%) of breast cancer and 10/11 (91%) SLN specimens from the metastatic group, but was not detected in 5/5 HCMV-negative, SLN-negative specimens. There was no statistically significant association between HCMV infection grades and progesterone receptor, estrogen receptor alpha and Elston grade status.

Conclusions

The role of HCMV in the pathogenesis of breast cancer is unclear. As HCMV proteins were mainly confined to neoplastic cells in primary breast cancer and SLN samples, our observations raise the question whether HCMV contributes to the tumorigenesis of breast cancer and its metastases.

Is human cytomegalovirus a target in cancer therapy?

Human cytomegalovirus (HCMV) is a herpesvirus that is prevalent in the human population. HCMV has recently been implicated in different cancer forms where it may provide mechanisms for oncogenic transformation, oncomodulation and tumour cell immune evasion. Moreover, antiviral treatment against HCMV has been shown to inhibit tumour growth in preclinical models. Here we describe the possible involvement of HCMV in cancer and discuss the potential molecular impact expression of HCMV proteins have on tumour cells and the surrounding tumour microenvironment.

Recent publications in medical microbiology and immunology: a retrospective

A look back is done to some clinical and basic research activities recently published in medical microbiology and immunology. The review covers clinical experiences and in vitro experiments to understand the emergency, pathogenicity, epidemic spread, and vaccine-based prevention of avian and swine-origin flu. Some new developments and concepts in diagnosis, (molecular) epidemiology, and therapy of AIDS, viral hepatitis C, and herpesvirus-associated diseases are outlined. Regulation of immune system has been discussed in a special issue 2010 including some aspects of CNS affections (measles). Mycobacterial infection and its prevention by modern recombinant vaccines have reached new interest, as well as new concepts of vaccination and prophylaxis against several other bacteria. Adaptation to host niches enables immune escape (example brucella) and determines virulence (example N. meningitidis). Chlamydia pneumoniae, previously considered to trigger atherosclerosis, is hypothetically associated to Alzheimer disease, while CMV, another putative trigger of atherosclerosis, gains evidence of oncomodulation in CNS tumor diseases. In terms of globalization, exotic virus infections are increasingly imported from southern countries.

Significant association of multiple human cytomegalovirus genomic Loci with glioblastoma multiforme samples

Viruses are appreciated as etiological agents of certain human tumors, but the number of different cancer types induced or exacerbated by viral infections is unknown. Glioblastoma multiforme (GBM)/astrocytoma grade IV is a malignant and lethal brain cancer of unknown origin. Over the past decade, several studies have searched for the presence of a prominent herpesvirus, human cytomegalovirus (HCMV), in GBM samples. While some have detected HCMV DNA, RNA, and proteins in GBM tissues, others have not. Therefore, any purported association of HCMV with GBM remains controversial. In most of the previous studies, only one or a select few viral targets were analyzed. Thus, it remains unclear the extent to which the entire viral genome was present when detected. Here we report the results of a survey of GBM specimens for as many as 20 different regions of the HCMV genome. Our findings indicate that multiple HCMV loci are statistically more likely to be found in GBM samples than in other brain tumors or epileptic brain specimens and that the viral genome was more often detected in frozen samples than in paraffin-embedded archival tissue samples. Finally, our experimental results indicate that cellular genomes substantially outnumber viral genomes in HCMV-positive GBM specimens, likely indicating that only a minority of the cells found in such samples harbor viral DNA. These data argue for the association of HCMV with GBM, defining the virus as oncoaccessory. Furthermore, they imply that, were HCMV to enhance the growth or survival of a tumor (i.e., if it is oncomodulatory), it would likely do so through mechanisms distinct from classic tumor viruses that express transforming viral oncoproteins in the overwhelming majority of tumor cells.

Detection of human cytomegalovirus in medulloblastomas reveals a potential therapeutic target

Medulloblastomas are the most common malignant brain tumors in children. They express high levels of COX-2 and produce PGE2, which stimulates tumor cell proliferation. Human cytomegalovirus (HCMV) is prevalent in the human population and encodes proteins that provide immune evasion strategies and promote oncogenic transformation and oncomodulation. In particular, HCMV induces COX-2 expression; STAT3 phosphorylation; production of PGE2, vascular endothelial growth factor, and IL-6; and tumor formation in vivo. Here, we show that a large proportion of primary medulloblastomas and medulloblastoma cell lines are infected with HCMV and that COX-2 expression, along with PGE2 levels, in tumors is directly modulated by the virus. Our analysis indicated that both HCMV immediate-early proteins and late proteins are expressed in the majority of primary medulloblastomas. Remarkably, all of the human medulloblastoma cell lines that we analyzed contained HCMV DNA and RNA and expressed HCMV proteins at various levels in vitro. When engrafted into immunocompromised mice, human medulloblastoma cells induced expression of HCMV proteins. HCMV and COX-2 expression correlated in primary tumors, cell lines, and medulloblastoma xenografts. The antiviral drug valganciclovir and the specific COX-2 inhibitor celecoxib prevented HCMV replication in vitro and inhibited PGE2 production and reduced medulloblastoma tumor cell growth both in vitro and in vivo. Ganciclovir did not affect the growth of HCMV-negative tumor cell lines. These findings imply an important role for HCMV in medulloblastoma and suggest HCMV as a novel therapeutic target for this tumor.

No evidence for a role of xenotropic murine leukaemia virus-related virus and BK virus in prostate cancer of German patients

Prostate cancer is one of the most prevalent types of cancer in men. Controversial data exist concerning the role of BKPyV and the xenotropic murine leukaemia virus-related gammaretrovirus (XMRV) in prostate cancer development. We therefore assessed the association between prostate cancer and viral infections. We could detect BKPyV in only 1 out of 85 prostate cancer samples, whereas none of the tissue samples showed evidence for XMRV positivity. Lack of detection of BKPyV and XMRV in prostate cancer tissues suggests that these viruses do not play a role in the pathogenesis of this type of cancer.

Viral effects on metabolism: changes in glucose and glutamine utilization during human cytomegalovirus infection

Human cytomegalovirus (HCMV) infection causes dramatic alterations of intermediary metabolism, similar to those found in tumor cells. In infected cells, glucose carbon is not completely broken down by the tricarboxylic acid (TCA) cycle for energy; instead, it is used biosynthetically. This process requires increased glucose uptake, increased glycolysis and the diversion of glucose carbon, in the form of citrate, from the TCA cycle for use in HCMV-induced fatty acid biosynthesis. The diversion of citrate from the TCA cycle (cataplerosis) requires induction of enzymes to promote glutaminolysis, the conversion of glutamine to α-ketoglutarate to maintain the TCA cycle (anaplerosis) and ATP production. Such changes could result in heretofore uncharacterized pathogenesis, potentially implicating HCMV as a subtle cofactor in many maladies, including oncogenesis. Recognition of the effects of HCMV, and other viruses, on host cell metabolism will provide new understanding of viral pathogenesis and novel avenues for antiviral therapy.

Oncomodulation by human cytomegalovirus: novel clinical findings open new roads

The question whether human cytomegalovirus may affect cancer diseases has been discussed (very controversially) for decades. There are convinced believers and strict opponents of the idea that HCMV might be able to play a role in the course of cancer diseases. In parallel, the number of published reports on the topic is growing. Recently published and presented (Ranganathan P, Clark P, Kuo JS, Salamat S, Kalejta RF. A Survey of Human Cytomegalovirus Genomic Loci Present in Glioblastoma Multiforme Tissue Samples. 35th Annual International Herpes Workshop, Salt Lake City, 2010) data on HCMV detection in glioblastoma tissues and colocalisation of HCMV proteins with cellular proteins known to be relevant for glioblastoma progression motivated us to recapitulate the current state of evidence.

Nuclear localization of tegument-delivered pp71 in human cytomegalovirus-infected cells is facilitated by one or more factors present in terminally differentiated fibroblasts

Herpesviral virions contain a tegument layer that consists primarily of viral proteins. The delivery of fully functional proteins to infected cells upon virion envelope fusion to the plasma membrane allows herpesviruses to modulate cellular activities prior to viral gene expression. Certain tegument proteins can also regulate viral processes. For example, the pp71 tegument protein encoded by the UL82 gene of human cytomegalovirus (HCMV) stimulates viral immediate early (IE) gene expression and thus acts to initiate the productive lytic infectious cycle. In terminally differentiated fibroblasts infected with HCMV, tegument-delivered pp71 traffics to the nucleus and degrades the cellular transcriptional corepressor Daxx to initiate viral IE gene expression and lytic replication. However, when HCMV infects incompletely differentiated cells, tegument-delivered pp71 remains in the cytoplasm, allowing the nucleus-localized Daxx protein to silence viral IE gene expression and promote the establishment of a latent infection in certain cell types. We sought to determine whether undifferentiated cells block the trafficking of tegument-delivered pp71 to the nucleus or whether differentiated cells facilitate the nuclear transport of tegument-delivered pp71. Heterogenous cell fusion experiments demonstrated that tegument-delivered pp71 found in the cytoplasm of undifferentiated NT2 cells could be driven into the nucleus by one or more factors provided by fully differentiated fibroblasts. Our data raise the intriguing possibility that latency is the default program launched by HCMV upon viral entry into cells and that lytic infection is initiated only in certain (differentiated) cells that can facilitate the delivery of incoming pp71 to the nucleus.

Androgen regulation of gene expression

The biological action of androgenic male sex steroid hormones in prostate tissue is mediated by the androgen receptor, a nuclear transcription factor. The transcriptional program of androgenic signaling in the prostate consists of thousands of gene targets whose products play a role in almost all cellular functions, including cellular proliferation, survival, lipid metabolism, and differentiation. This review will provide a summary of the most recent data regarding androgen-regulated target genes and modulation of androgen receptor activity, especially with regard to androgen-dependent and castration-recurrent prostate cancer.

Chronic viral infection and primary central nervous system malignancy

Primary central nervous system (CNS) tumors cause significant morbidity and mortality in both adults and children. While some of the genetic and molecular mechanisms of neuro-oncogenesis are known, much less is known about possible epigenetic contributions to disease pathophysiology. Over the last several decades, chronic viral infections have been associated with a number of human malignancies. In primary CNS malignancies, two families of viruses, namely polyomavirus and herpesvirus, have been detected with varied frequencies in a number of pediatric and adult histological tumor subtypes. However, establishing a link between chronic viral infection and primary CNS malignancy has been an area of considerable controversy, due in part to variations in detection frequencies and methodologies used among researchers. Since a latent viral neurotropism can be seen with a variety of viruses and a widespread seropositivity exists among the population, it has been difficult to establish an association between viral infection and CNS malignancy based on epidemiology alone. While direct evidence of a role of viruses in neuro-oncogenesis in humans is lacking, a more plausible hypothesis of neuro-oncomodulation has been proposed. The overall goals of this review are to summarize the many human investigations that have studied viral infection in primary CNS tumors, discuss potential neuro-oncomodulatory mechanisms of viral-associated CNS disease and propose future research directions to establish a more firm association between chronic viral infections and primary CNS malignancies.

Measurement of cytotoxic T lymphocyte activity of human cytomegalovirus seropositive individuals by a highly sensitive coupled luminescent method

A coupled luminescent method (CLM) based on glyceraldehyde-3-phosphate dehydrogenase released from injured target cells was used to evaluate the cytotoxicity of antigen-specific HLA class I-restricted CTLs. In contrast to established methods, CLM does not require the pretreatment of target cells with radioactive or toxic labeling substances. CTLs from healthy HLA-A2 positive donors were stimulated by autologous dendritic cells (DCs) pulsed with HLA-A2 restricted HCMV-pp65 nonamer peptides. HLA-A2 positive T2 cells or autologous monocytes pulsed with HCMV-pp65 nonamer peptide served as target cells. Lysis was detected only in HCMV-pp65-pulsed target cells incubated with CTLs from seropositive donors stimulated by HCMV-pp65-pulsed DCs. After 3 days, stimulation 38% of T2 cells and 17% of monocytes were lysed at an effector to target ratio of 8:1. In conclusion, CLM represents a highly sensitive, fast, material-saving and non-toxic/non-radioactive method for the measurement of antigen-specific CTL cytotoxic activity.