Specific localisation of human cytomegalovirus nucleic acids and proteins in human colorectal cancer

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.

Hijacking GPCRs by viral pathogens and tumor

G protein-coupled receptors (GPCRs) constitute the largest family of molecules that transduce signals across the plasma membrane. Herpesviruses are successful pathogens that evolved diverse mechanisms to benefit their infection. Several human herpesviruses express GPCRs to exploit cellular signaling cascades during infection. These viral GPCRs demonstrate distinct biochemical and biophysical properties that result in the activation of a broad spectrum of signaling pathways. In immune-deficient individuals, human herpesvirus infection and the expression of their GPCRs are implicated in virus-associated diseases and pathologies. Emerging studies also uncover diverse mutations in components, particularly GPCRs and small G proteins, of GPCR signaling pathways that render the constitutive activation of proliferative and survival signal, which contributes to the oncogenesis of various human cancers. Hijacking GPCR-mediated signaling is a signature shared by diseases associated with constitutively active viral GPCRs and cellular mutations activating GPCR signaling, exposing key molecules that can be targeted for anti-viral and anti-tumor therapy.

Cytomegalovirus and Mucoepidermoid carcinoma: A possible causal relationship? A pilot study

BACKGROUND

Human cytomegalovirus (CMV) infection has tropism for salivary gland ductal epithelium and establishes a persistent and lifelong infection. Mucoepidermoid carcinoma (MEC) is the most common salivary gland tumor. Recent studies have established that mouse CMV-induced tumorigenesis displays histologic and molecular characteristics similar to human MEC. We wished to explore further down the lane by analyzing the expression of pp65 and the key oncogenic signaling pathway in cases of MEC and their etiological relevance in the Indian scenario as a pilot study.

MATERIALS AND METHODS

Histopathologically confirmed cases of MEC (n = 4) and normal salivary gland tissue (n = 4) were subjected to immunohistochemical analysis using the markers pp65 and epidermal growth factor receptor (EGFR).

RESULTS

The pp65 antigen expression was found to be negative in all the studied cases and one case of high-grade MEC showed EGFR expression.

CONCLUSION

The purpose of the study was to explore the role of CMV in the development of MEC, as it might help to exploit this etiological agent as a therapeutic target. Similar to human papillomavirus (HPV), these might identify a subset of neoplasms with a varied biological behavior and alternative therapies. However, this vision is obscured by contradicting evidence in the literature. As of today, surgery remains the only best possible management for these patients unless proven otherwise.

Cytomegalovirus-targeted immunotherapy and glioblastoma: hype or hope?

Malignant gliomas, including glioblastoma (GBM), are the most common primary brain tumors. Despite extensive research only modest gains have been made in long-term survival. Standard of care involves maximizing safe surgical resection followed by concurrent chemoradiation with temozolomide. Immunotherapy for GBM is an area of intense research in recent years. New immunotherapies, although promising, have not been integrated into standard practice. Human cytomegalovirus (HCMV) is a DNA virus of the family Herpesviridae. Human seroprevalence is approximately 80%, and in most cases, is associated with asymptomatic infection. HCMV may be an important agent in the initiation, promotion and/or progression of tumorigenesis. Regardless of a possible etiologic role in GBM, interest has centered on exploiting this association for development of immunomodulatory therapies.

Clinical significance of expression of human cytomegalovirus genes in colorectal cancer

AIM: To detect the expression of human cytomegalovirus (HCMV) infection related genes in colorectal cancer tissues and their relationship with clinicopathological features of colorectal cancer.

METHODS: HCMV UL135, UL136, US28 and IE1 gene expression in colorectal cancer tissues and corresponding adjacent normal samples was determined by nested PCR. The accuracy of nested PCR results was confirmed by SDS-PAGE and DNA sequencing analysis. The relationship between HCMV gene expression and clinicopathological features of patients with colorectal cancer was also analyzed. Statistical methods included Chi-square test or Fisher exact probability test and logistic regression model analysis.

RESULTS: The results of nested PCR were confirmed to be reliable. The positive expression rates of UL135, UL136 and US28 genes in the colorectal cancer tissues were 35.0%, 15.0% and 60.0%, respectively; and they were 16.7%, 1.7% and 18.3% in corresponding normal tissues. The positive expression rates of UL135, UL136 and US28 genes in the colorectal cancer tissues were significantly higher than those in corresponding normal tissues (P < 0.05 for all). There was no significant difference in the positive expression rate of IE1 between colorectal cancer tissues (13.3%) and corresponding normal tissues (10%). The expression of UL135, ULi136 and IE1 genes had no significant association with gender, age, tumor size, histological differentiation, metastasis or Dukes stage. The expression of US28 had a significant association with lymph node metastasis and Dukes stage, but not with age, gender, tumor size or histological differentiation.

CONCLUSION: UL135, UL136 and US28 gene expression is more often found in colorectal cancer tissues than in corresponding normal tissues, among which US28 has a significant association with lymph node metastasis and Dukes stage of colorectal cancer. Our findings suggest that some HCMV genes may play a role in the occurrence and development of colorectal cancer.

Simian virus 40 is not likely involved in the development of colorectal adenocarcinoma

Aim: The purpose of this study is to investigate the role of simian virus 40 (SV40) in colorectal cancer development by assessing the presence of DNA and protein product of SV40 in colorectal cancer. Materials & methods: Extracted DNA from 83 archival colorectal adenocarcinoma samples and 35 control samples of noncancerous colon tissue was analyzed for SV40 using PCR-based techniques. The expression of the protein product was assessed using immunohistochemical staining. Results: All tested tumors and control cases failed to detect SV40 DNA in PCR assays. Furthermore, immunohistochemical staining did not show any viral proteins in both cancer and control cases. Conclusion: These results indicated that there is no association between SV40 and the development of colorectal adenocarcinomas.

Cytomegalovirus and immunotherapy: opportunistic pathogen, novel target for cancer and a promising vaccine vector

Cytomegalovirus (CMV) is a β-herpesvirus that infects most people in the world and is almost always asymptomatic in the healthy host. However, CMV persists for life, requiring continuous immune surveillance to prevent disease and thus, CMV is a frequent complication in immune compromised patients. Many groups have been exploring the potential for adoptive T-cell therapies to control CMV reactivation as well as the progression of solid tumors harboring CMV. In addition, CMV itself is being explored as a vaccine vector for eliciting potent T-cell responses. This review will discuss key features of the basic biology of CMV-specific T cells as well as highlighting unanswered questions and ongoing work in the development of T-cell-based immunotherapies to target CMV.

Expression of cytomegalovirus in glioblastoma multiforme: Myth or reality?

A role for human cytomegalovirus (HCMV) in the pathogenesis of glioblastoma multiforme (GBM) was proposed more than a decade ago and has since generated a considerable debate as a possible therapeutic target. We investigate the presence of HCMV in the specimens of patients with GBM treated in our centre. This is a retrospective cohort study to investigate the presence of HCMV by routine immunohistochemical stains and polymerase chain reaction (PCR)-based molecular analysis on formalin-fixed-paraffin-embedded tissue of all patients with GBM treated in our hospital in 2009-2013 (5 years). The evaluation of positivity by immunohistochemistry (IHC) was semi-quantitative. The molecular analysis was performed by extracting the tumour DNA from representative paraffin-embedded tissue blocks and amplified for detection by a sensitive real time PCR (RT-PCR) CMV assay. During the study period, we treated 45 patients with GBM; however, adequate pathology tissue materials were available only for 32 patients. All the pathology material was reviewed and the diagnosis was confirmed. All the cases were found to be negative for CMV expression by our IHC and RT-PCR CMV assay. Our study has shown no expression of CMV in GBM. Our results were similar to other recent reports that concluded insufficient evidence to recommend routine testing for CMV in GBM or treatment as an add-on therapy.

Clinical relevance between human cytomegalovirus infection and colorectal cancer

AIM: To investigate the clinical relevance between human cytomegalovirus (HCMV) infection and colorectal cancer.

METHODS: The specific immunoglobulin G (IgG) and IgM antibodies against HCMV in sera of colorectal cancer patients (n = 60), patients with colorectal polyps (n = 60) and health controls (n = 60) were detected by chemiluminescence immunoassay. HCMV infection in colorectal cancer tissues and corresponding adjacent normal samples were determined through the detection of UL138 gene by nested PCR and in situ hybridization. The relationships between HCMV infection and clinical features of colorectal cancer were analyzed.

RESULTS: The positive rates of HCMV-IgG in the colorectal cancer group, colorectal polyps group and healthy control group were 95.0% (57/60), 98.3% (59/60), and 96.7% (58/60), respectively; the positive rates of HCMV-IgM were 5.0% (3/60), 1.7% (1/60) and 1.7% (1/60), respectively. There were no statistically significant differences in the positive rates of HCMV-IgG and HCMV-IgM among the three groups. However, there was a significant difference between colorectal cancer tissues and corresponding normal tissues in HCMV-UL138 detection. The positive rates of HCMV-UL138 were 65.6% (19/32) and 62.5% (20/32) in colorectal cancer tissues samples, and 12.5% (4/32) and 9.4% (3/32) in corresponding normal tissues as revealed by nested PCR detection and in situ hybridization, respectively. HCMV infection had no significant association with age, gender, location of mass, tumor size, histological differentiation, metastasis or Dukes stage.

CONCLUSION: HCMV infection is associated with colorectal cancer. Compared with corresponding normal epithelium, the neoplastic epithelium may be preferentially infected by the HCMV. This research suggests that HCMV infection may play a role in the occurrence and development of colorectal cancer.

Human cytomegalovirus and primary intracranial tumours: frequency of tumour infection and lack of correlation with systemic immune anti-viral responses

AIMS

Human cytomegalovirus (HCMV) is a ubiquitous beta human herpesvirus able to influence infected cell survival and proliferation and to modulate the host immune response. As there is accumulating evidence that HCMV is detected in primary intracranial astrocytic tumours, in this study we looked for the presence of HCMV in intracranial tumours and tried to correlate this eventual presence with the anti-HCMV systemic immunoreactivity and with the detection of HCMV in peripheral blood.

METHODS

In this study, we analysed 43 glioblastomas (GBM), 14 oligodendrogliomas (OL) and 20 meningiomas (MG) by immunofluorescence (IF) targeting HCMV immediate early antigen (IE1) and by nested PCR (nPCR) amplifying HCMV glycoprotein B (gB).

RESULTS

Detection of IE1 by IF showed the presence of HCMV in 70% of GBM, 57% of OL and 85% of MG, in contrast to gB nPCR, which detected HCMV in only 50% of GBM, 38% of OL and 46% of MG. Unexpectedly, HCMV DNA and antigens were detected within GBM, OL and MG of patients that exhibit negative viral serology. More surprisingly, PCR on the peripheral blood did not detect HCMV in patients with a HCMV-positive tumour.

CONCLUSIONS

Our results are in agreement with previous observations demonstrating HCMV in glial tumours and highlight the presence of HCMV in meningiomas. We also showed that anti-HCMV specific systemic immunoreactivity and detection of HCMV in peripheral blood are not predictive of HCMV presence in primary intracranial tumours.

Human Cytomegalovirus Promotes Survival of Infected Monocytes via a Distinct Temporal Regulation of Cellular Bcl-2 Family Proteins

Monocytes play a key role in the hematogenous dissemination of human cytomegalovirus (HCMV) to target organ systems. To infect monocytes and reprogram them to deliver infectious virus, HCMV must overcome biological obstacles, including the short life span of monocytes and their antiviral proapoptotic response to infection. We have shown that virally induced upregulation of cellular Mcl-1 promotes early survival of HCMV-infected monocytes, allowing cells to overcome an early apoptotic checkpoint at around 48 h postinfection (hpi). Here, we demonstrate an HCMV-dependent shift from Mcl-1 as the primary antiapoptotic player to the related protein, Bcl-2, later during infection. Bcl-2 was upregulated in HCMV-infected monocytes beginning at 48 hpi. Treatment with the Bcl-2 antagonist ABT-199 only reduced the prosurvival effects of HCMV in target monocytes beginning at 48 hpi, suggesting that Mcl-1 controls survival prior to 48 hpi, while Bcl-2 promotes survival after 48 hpi. Although Bcl-2 was upregulated following viral binding/signaling through cellular integrins (compared to Mcl-1, which is upregulated through binding/activation of epidermal growth factor receptor [EGFR]), it functioned similarly to Mcl-1, adopting the early role of Mcl-1 in preventing caspase-3 cleavage/activation. This distinct, HCMV-induced shift from Mcl-1 to Bcl-2 occurs in response to a cellular upregulation of proapoptotic Bax, as small interfering RNA (siRNA)-mediated knockdown of Bax reduced the upregulation of Bcl-2 in infected monocytes and rescued the cells from the apoptotic effects of Bcl-2 inhibition. Our data demonstrate a distinct survival strategy whereby HCMV induces a biphasic regulation of cellular Bcl-2 proteins to promote host cell survival, leading to viral dissemination and the establishment of persistent HCMV infection.

IMPORTANCE

Hematogenous dissemination of HCMV via infected monocytes is a crucial component of the viral survival strategy and is required for the establishment of persistent infection and for viral spread to additional hosts. Our system of infected primary human blood monocytes provides us with an opportunity to answer specific questions about viral spread and persistence in in vivo-relevant myeloid cells that cannot be addressed with the more traditionally used replication-permissive cells. Our goal in examining the mechanisms whereby HCMV reprograms infected monocytes to promote viral dissemination is to uncover new targets for therapeutic intervention that would disrupt key viral survival and persistence strategies. Because of this important role in maintaining survival of HCMV-infected monocytes, our new data on the role of Bcl-2 regulation during viral infection represents a promising molecular target for mitigating viral spread and persistence.

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.

Enhanced neutrophil activity is associated with shorter time to tumor progression in glioblastoma patients

Glioblastoma multiforme (GBM) is a highly malignant tumor with a poor outcome that is often positive for human cytomegalovirus (HCMV). GBM patients often have excessive numbers of neutrophils and macrophages near and within the tumor. Here, we characterized the cytokine patterns in the blood of GBM patients with and without Valganciclovir treatment. Furthermore, we determined whether neutrophil activation is related to HCMV status and patient outcome. Blood samples for analyses of cytokines and growth factors were collected from 42 GBM patients at the time of diagnosis (n = 42) and at weeks 12 and 24 after surgery. Blood neutrophils of 28 GBM patients were examined for CD11b expression. The levels of pro- and anti-inflammatory cytokines and chemokines-including interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, IL-17A, transforming growth factor (TGF)-β1, interferon-γ, interferon-α, tumor necrosis factor α, and monocyte chemoattractant protein (MCP)-1were analyzed with a bead-based flow cytometry assay. During the first six months after surgery, neutrophil activity was increased in 12 patients and was unchanged or decreased in 16. Patients with increased neutrophil activity had enhanced IL-12p70, high grade HCMV and a shorter time to tumor progression (TTP) than patients without or decreased neutrophil activity (median TTP; 5.4 vs. 12 months, 95% confidence interval; 1.6-10 vs. 0.1-0.6, hazard ratio = 3 vs. 0.4, p = 0.004). The levels of IL-12p70 were significantly decreased in Valganciclovir treated patients (n = 22, T 12W vs. T 24W, p = 0.03). In conclusion, our findings suggest that neutrophil activation is an early sign of tumor progression in GBM patients.

Synthetic DNA approach to cytomegalovirus vaccine/immune therapy

There is no licensed vaccine or cure for human cytomegalovirus (CMV), a ubiquitous β-herpes virus that infects 60-95 % of adults worldwide. Infection is a major cause of congenital abnormalities in newborns, contributes to development of childhood cerebral palsy and medulloblastoma, can result in severe disease in immunocompromised patients, and is a major impediment during successful organ transplantation. While CMV has been increasingly associated with numerous inflammatory diseases and cancers, only recently has it been correlated with increased risk of heart disease in adults, the number-one killer in the USA. These data, among others, suggest that subclinical CMV infection, or microinfection, in healthy individuals may play more of a causative role than an epiphenomenon in development of CMV-associated pathologies. Due to the myriad of diseases and complications associated with CMV, an efficacious vaccine would be highly valuable in reducing human morbidity and mortality as well as saving billions of dollars in annual health-care costs and disability adjusted life years (DALY) in the developing world. Therefore, the development of a safe efficacious CMV vaccine or immune therapy is paramount to the public health. This review aims to provide a brief overview on aspects of CMV infection and disease and focuses on current vaccine strategies. The use of new synthetic DNA vaccines might offer one such approach to this difficult problem.

Modeling cytomegalovirus infection in mouse tumor models

The hypothesis that cytomegalovirus (CMV) modulates cancer is evolving. Originally discovered in glioblastoma in 2002, the number of cancers, where intratumoral CMV antigen is detected, has increased in recent years suggesting that CMV actively affects the pathobiology of certain tumors. These findings are controversial as several groups have also reported inability to replicate these results. Regardless, several clinical trials for glioblastoma are underway or have been completed that target intratumoral CMV with anti-viral drugs or immunotherapy. Therefore, a better understanding of the possible pathobiology of CMV in cancer needs to be ascertained. We have developed genetic, syngeneic, and orthotopic malignant glioma mouse models to study the role of CMV in cancer development and progression. These models recapitulate for the most part intratumoral CMV expression as seen in human tumors. Additionally, we discovered that CMV infection in Trp53^−/+ mice promotes pleomorphic rhabdomyosarcomas. These mouse models are not only a vehicle for studying pathobiology of the viral-tumor interaction but also a platform for developing and testing cancer therapeutics.

Cytomegalovirus in human brain tumors: Role in pathogenesis and potential treatment options

During the last years increasing evidence implies that human cytomegalovirus (CMV) can be attributed to human malignancies arising from numerous tissues. In this perspective, we will review and discuss the potential mechanisms through which CMV infection may contribute to brain tumors by affecting tumor cell initiation, progression and metastasis formation. Recent evidence also suggests that anti-CMV treatment results in impaired tumor growth of CMV positive xenografts in animal models and potentially increased survival in CMV positive glioblastoma patients. Based on these observations and the high tumor promoting capacity of this virus, the classical and novel antiviral therapies against CMV should be revisited as they may represent a great promise for halting tumor progression and lower cancer deaths.

Direct and Indirect Effects of Cytomegalovirus-Induced γδ T Cells after Kidney Transplantation

Despite effective anti-viral therapies, cytomegalovirus (CMV) is still associated with direct (CMV disease) and indirect effects (rejection and poor graft survival) in kidney transplant recipients. Recently, an unconventional T cell population (collectively designated as Vδ2^neg γδ T cells) has been characterized during the anti-CMV immune response in all solid-organ and bone-marrow transplant recipients, neonates, and healthy people. These CMV-induced Vδ2^neg γδ T cells undergo a dramatic and stable expansion after CMV infection, in a conventional “adaptive” manner. Similarly, as CMV-specific CD8+ αβ T cells, they exhibit an effector/memory TEMRA phenotype and cytotoxic effector functions. Activation of Vδ2^neg γδ T cells by CMV-infected cells involves the γδ T cell receptor (TCR) and still ill-defined co-stimulatory molecules such as LFA-1. A multiple of Vδ2^neg γδ TCR ligands are apparently recognized on CMV-infected cells, the first one identified being the major histocompatibility complex-related molecule endothelial protein C receptor. A singularity of CMV-induced Vδ2^neg γδ T cells is to acquire CD16 expression and to exert an antibody-dependent cell-mediated inhibition on CMV replication, which is controlled by a specific cytokine microenvironment. Beyond the well-demonstrated direct anti-CMV effect of Vδ2^neg γδ T cells, unexpected indirect effects of these cells have been also observed in the context of kidney transplantation. CMV-induced Vδ2^neg γδ T cells have been involved in surveillance of malignancy subsequent to long-term immunosuppression. Moreover, CMV-induced CD16+ γδ T cells are cell effectors of antibody-mediated rejection of kidney transplants, and represent a new physiopathological contribution to the well-known association between CMV infection and poor graft survival. All these basic and clinical studies paved the road to the development of a future γδ T cell-based immunotherapy. In the meantime, γδ T cell monitoring should prove a valuable immunological biomarker in the management of CMV infection.

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.

Detection of human cytomegalovirus in patients with colorectal cancer by nested-PCR

BACKGROUND

The association of colorectal cancer with human cytomegalovirus (HCMV) is a controversial issue in cancer research. This study aimed to identify the HCMV virus in colorectal cancer tissues and to investigate the association of HCMV with colorectal cancer. In this study, 50 cancer tissue samples and 50 samples without colon cancer were studied in order to identify the HCMV virus through nested-polymerase chain reaction. The virus was identified in 15 cases of colorectal cancer tissues (15/50) and in 5 cases of normal tissues (5/50). Eight cases of adenocarcinoma tissues were in a moderately differentiated stage, and 7 cases had well-differentiated stage tissues that were positive for viral DNA. The findings were statistically evaluated at a significance level of p<0.05. The HCMV virus could play a role in creating malignancy and the progress of cancer through the process of oncomodulation.

The oncomodulatory role of human cytomegalovirus in colorectal cancer: implications for clinical trials

Increasing evidence suggests that human cytomegalovirus (HCMV), a beta-herpes virus that chronically infects human beings, is associated with colorectal cancer (CRC). The viral nucleic acids specifically localized to the neoplastic mucosal epithelium of CRC, while tumoral presence of HCMV independently predicted a poor outcome in elderly patients. In the past decade, the concept of “oncomodulation” of HCMV in human cancers has been formulated. In CRC, changes in the tumor microenvironment are closely related to cancer behavior and prognosis, while the underlying mechanism driving these changes remains unclear. As HCMV affects multiple cellular functions, including signal pathways that regulate angiogenesis, apoptosis, cell invasiveness, and anti-cancer immunity, the virus potentially exerts oncomodulatory effects in the tumor microenvironment of CRC. Here, we summarize the current knowledge about the association between HCMV and CRC and suggest future perspectives on both research and anti-cancer therapy of CRC.

MicroRNA miR-21 attenuates human cytomegalovirus replication in neural cells by targeting Cdc25a

Congenital human cytomegalovirus (HCMV) infection is a leading cause of birth defects, primarily manifesting as neurological disorders. HCMV infection alters expression of cellular microRNAs (miRs) and induces cell cycle arrest, which in turn modifies the cellular environment to favor virus replication. Previous observations found that HCMV infection reduces miR-21 expression in neural progenitor/stem cells (NPCs). Here, we show that infection of NPCs and U-251MG cells represses miR-21 while increasing the levels of Cdc25a, a cell cycle regulator and known target of miR-21. These opposing responses to infection prompted an investigation of the relationship between miR-21, Cdc25a, and viral replication. Overexpression of miR-21 in NPCs and U-251MG cells inhibited viral gene expression, genome replication, and production of infectious progeny, while shRNA-knockdown of miR-21 in U-251MG cells increased viral gene expression. In contrast, overexpression of Cdc25a in U-251MG cells increased viral gene expression and production of infectious progeny and overcame the inhibitory effects of miR-21 overexpression. Three viral gene products-IE1, pp71, and UL26-were shown to inhibit miR-21 expression at the transcriptional level. These results suggest that Cdc25a promotes HCMV replication and elevation of Cdc25a levels after HCMV infection are due in part to HCMV-mediated repression of miR-21. Thus, miR-21 is an intrinsic antiviral factor that is modulated by HCMV infection. This suggests a role for miR-21 downregulation in the neuropathogenesis of HCMV infection of the developing CNS.

IMPORTANCE

Human cytomegalovirus (HCMV) is a ubiquitous pathogen and has very high prevalence among population, especially in China, and congenital HCMV infection is a major cause for birth defects. Elucidating virus-host interactions that govern HCMV replication in neuronal cells is critical to understanding the neuropathogenesis of birth defects resulting from congenital infection. In this study, we confirm that HCMV infection downregulates miR-21 but upregulates Cdc25a. Further determined the negative effects of cellular miRNA miR-21 on HCMV replication in neural progenitor/stem cells and U-251MG glioblastoma/astrocytoma cells. More importantly, our results provide the first evidence that miR-21 negatively regulates HCMV replication by targeting Cdc25a, a vital cell cycle regulator. We further found that viral gene products of IE1, pp71, and UL26 play roles in inhibiting miR-21 expression, which in turn causes increases in Cdc25a and benefits HCMV replication. Thus, miR-21 appears to be an intrinsic antiviral factor that represents a potential target for therapeutic intervention.

DNA repair mechanisms and human cytomegalovirus (HCMV) infection

Herpesvirus infections, such as those induced by human cytomegalovirus (HCMV), induce specific DNA damages. DNA damages can lead to cell mutation, death, apoptosis and immune system activation. Various types of DNA damage are repaired through multiple repair pathways, such as base excision, nucleotide excision, homologous recombination and nonhomologous end joining. Changes in the activity of DNA repair proteins during viral infection can cause disturbances in the DNA repair system and change its mechanisms. This report reviews results from studies, assaying a DNA repair system in HCMV infection.

Human cytomegalovirus viral load in tumor and peripheral blood samples of patients with malignant gliomas

Malignant gliomas are the most common primary brain tumors in adults. The disease has no known etiology, progresses rapidly, and is fatal despite current therapies. Human cytomegalovirus (HCMV) is a beta herpes virus that is trophic for glial cells and infects 50% to 90% of the adult human population. HCMV-mediated disease in immunosuppressed patients has highlighted the possible role of this virus in the development of other diseases, particularly inflammatory diseases such as vascular diseases, autoimmune diseases, and certain malignancies. Sensitive detection of viral DNA, mRNA, and antigens in tumor tissues, as well as seroepidemiologic evidence, suggest a link between HCMV and several human malignancies. HCMV gene products are proposed to dysregulate multiple cellular pathways involved in oncogenesis, such as cell cycle regulation, apoptosis, migration, and angiogenesis. These theories, currently being researched, suggest that HCMV acts as an oncomodulator in malignancies. We investigated the association between HCMV infection and reactivation, and malignant gliomas. An open, matched case-control, parallel group pilot study was performed in a tertiary referral center. The HCMV viral load in peripheral blood and tumor samples of 19 patients newly diagnosed with glioblastoma multiforme was compared with a matched control cohort comprising 19 patients newly diagnosed with non-malignant brain tumors. There was no significant correlation between peripheral blood and tumor tissue HCMV viral load in patients with glioblastoma multiforme compared to the control cohort. The findings of the present study did not support an oncomodulatory role for HCMV in malignant gliomas.

Upregulation of Toll-like receptor 2 expression in colorectal cancer infected by human cytomegalovirus

The aim of the present study was to investigate the association between Toll-like receptor 2 (TLR2) expression and human cytomegalovirus (HCMV) in colorectal carcinoma by detecting the expression of IE1-72, TLR2, TLR4 and tumor necrosis factor (TNF)-α in colorectal carcinoma and colon adenoma samples, as well as by analyzing the mRNA levels of the proteins in colon cancer cell lines, following HCMV infection. For this study, 56 colorectal cancer and 36 colon adenoma samples were collected, and normal mucosal tissue adjacent to the tumor was used as the control. The expression of the IE1-72, TLR2, TLR4, nuclear factor (NF)-κB and TNF-α protein was detected by immunohistochemistry. Cells from the SW480 human colon carcinoma cell line were infected with HCMV. The expression of IE1-72, TLR2, TLR4, NF-κB and TNF-α mRNA was quantified at different time points prior to and following infection. The positive expression rate of IE1-72 was 44.6% (25/56) in colorectal cancer and 41.7% (15/36) in colon adenoma. These rates were significantly higher when compared with the 12.5% (7/56) observed in the normal tissues adjacent to the cancer tissues (P<0.05). The expression levels of TLR2, TLR4, NF-κB and TNF-α in colorectal cancer and adenoma were also higher than those in the control tissues. Furthermore, the expression of IE1-72 in colorectal cancer tissues was found to correlate with TLR2 and TLR4, and the correlation coefficients were 0.515 and 0.462, respectively. Following the infection of SW480 cells, the mRNA levels of TLR2 and TNF-α increased gradually from 6 h, peaked at 48 h, and then decreased gradually. No significant differences in TLR4 and NF-κB expression were identified. The results of the present study indicated that there is a specific association between HCMV and the occurrence and development of colorectal cancer, which may be facilitated by the TLR2 signaling pathway.

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.

Viral infections and colorectal cancer: a systematic review of epidemiological studies

Numerous studies have found the presence of viral DNA in colorectal tumor tissues. However, whether viral infections contribute to the risk of colorectal cancer (CRC) is still under debate. We aimed to provide an overview of published epidemiological studies on the association between viral infections and CRC. A systematic literature search was performed in PubMed to find relevant studies published until 8 May 2014. Information collected included study population, sample type, laboratory method and prevalence of viral infection in cancer or precancer patients and controls. We found 41 studies that fulfilled the selection criteria, all of which had cross-sectional or case-control designs, and most of which were of small to moderate size. Viral infections included human papillomaviruses (HPV), human polyomaviruses, human herpesviruses, human bocavirus and Inoue-Melnick virus. Inconsistent results were observed across studies. Many studies reported higher viral DNA prevalence in tumor tissues than in normal noncancerous tissues either in the same patients or in CRC-free controls. However, potential contamination or temporal sequence of the infection and cancer development were often unclear. Seroprevalence studies assessing antibody titers indicative of viral infections did not find statistically significant differences between CRC cases and healthy controls. Overall published evidence on the role of viral infections in CRC etiology remains limited. Given the potential importance of viral infections and their implication for prevention, there is a strong need for large, methodologically rigorous epidemiological studies.

eXamine: exploring annotated modules in networks

Background

Biological networks have a growing importance for the interpretation of high-throughput “omics” data. Integrative network analysis makes use of statistical and combinatorial methods to extract smaller subnetwork modules, and performs enrichment analysis to annotate the modules with ontology terms or other available knowledge. This process results in an annotated module, which retains the original network structure and includes enrichment information as a set system. A major bottleneck is a lack of tools that allow exploring both network structure of extracted modules and its annotations.

Results

This paper presents a visual analysis approach that targets small modules with many set-based annotations, and which displays the annotations as contours on top of a node-link diagram. We introduce an extension of self-organizing maps to lay out nodes, links, and contours in a unified way. An implementation of this approach is freely available as the Cytoscape app eXamine

Conclusions

eXamine accurately conveys small and annotated modules consisting of several dozens of proteins and annotations. We demonstrate that eXamine facilitates the interpretation of integrative network analysis results in a guided case study. This study has resulted in a novel biological insight regarding the virally-encoded G-protein coupled receptor US28.

Tumoral presence of human cytomegalovirus is associated with shorter disease-free survival in elderly patients with colorectal cancer and higher levels of intratumoral interleukin-17

Infectious diseases are closely related to cancer. Human cytomegalovirus (HCMV) has been implicated in the promotion of tumour growth, and is present in the tumour specimens of colorectal cancer (CRC). This study aimed to investigate whether tumoral presence of HCMV is associated with a different clinical outcome in elderly patients with CRC. We analysed archived tumour specimens from 95 CRC patients aged ≥65 years. HCMV was detected by PCR. Clinical, pathological, disease-free and overall survival data were compared between patients with HCMV-positive and HCMV-negative tumours. A quantitative RT-PCR array was used to evaluate the expression levels of cytokines genes of T-helper subpopulations in tumours. In the Kaplan-Meier analysis of the 81 patients who underwent curative surgery, 39 patients with HCMV-positive tumours had a lower disease-free survival rate (p 0.024). For patients with stage II or stage III tumours, tumoral HCMV status correlated with disease-free survival more closely than the traditional histopathological staging methods. In a multivariate Cox proportional hazard model, tumoral presence of HCMV independently predicted tumour recurrence in 5 years (hazard ratio 4.42; 95% CI 1.54-12.69, p 0.006). The qRT-PCR analysis of ten stage II tumours showed that the gene expression levels of interleukin-17-the signature cytokine of T-helper 17 cells-and its receptor, interleukin-17 receptor C, were higher in the five HCMV-positive tumours. Our results suggest that the presence of HCMV in CRC is associated with poorer outcome in elderly patients. How the virus interacts with the tumour microenvironment should be further investigated.

Does the existence of HCMV components predict poor prognosis in glioma?

Human cytomegalovirus (HCMV) has been associated with malignant gliomas. The objective of the present study was to further investigate the existence and prognostic value of HCMV components in gliomas. Using immunohistochemical staining, HCMV proteins IE1-72 and pp65 were examined in 67 glioma specimens of various histologic grades, in comparison to 6 -control brain tissue samples. The HCMV DNA was measured in both the tumor tissues and the peripheral blood of the patients, using nested PCR. Kaplan-Meier analysis and Cox proportional hazards models were used to analyzed the prognostic value of HCMV components in glioma tissues. IE1-72 was detected in 76.1% (51/67) of glioma tissues, and pp65 was detected in 65.7% (44/67) of glioma tissues. HCMV DNA was detected in 52.2% (35/67) of glioma tissues and 29.9% (20/67) of peripheral blood samples of glioma patients. These HCMV components were not detected in control brain tissue. However, the existence of HCMV components showed no significant correlation with the prognosis of glioma patients. Our results demonstrate that although HCMV proteins and nucleic acids are present in gliomas, they do not correlate with the prognosis. The role of HCMV in gliomas needs to be carefully interpreted.

Cytomegalovirus contributes to glioblastoma in the context of tumor suppressor mutations

To study the controversial role of cytomegalovirus (CMV) in glioblastoma, we assessed the effects of murine CMV (MCMV) perinatal infection in a GFAP-cre; Nf1(loxP/+); Trp53(-/+) genetic mouse model of glioma (Mut3 mice). Early on after infection, MCMV antigen was predominantly localized in CD45+ lymphocytes in the brain with active viral replication and local areas of inflammation, but, by 7 weeks, there was a generalized loss of MCMV in brain, confirmed by bioluminescent imaging. MCMV-infected Mut3 mice exhibited a shorter survival time from their gliomas than control Mut3 mice perinatally infected with mock or with a different neurotropic virus. Animal survival was also significantly shortened when orthotopic gliomas were implanted in mice perinatally infected with MCMV versus controls. MCMV infection increased phosphorylated STAT3 (p-STAT3) levels in neural stem cells (NSC) harvested from Mut3 mice subventricular zone, and, in vivo, there was increased p-STAT3 in NSCs in MCMV-infected compared with control mice. Of relevance, human CMV (HCMV) also increased p-STAT3 and proliferation of patient-derived glioblastoma neurospheres, whereas a STAT3 inhibitor reversed this effect in vitro and in vivo. These findings thus associate CMV infection to a STAT3-dependent modulatory role in glioma formation/progression in the context of tumor suppressor mutations in mice and possibly in humans.

Overview of human cytomegalovirus pathogenesis

Human cytomegalovirus (HCMV) is a human pathogen that infects greater than 50 % of the human population. HCMV infection is usually asymptomatic in most individuals. That is, primary infection or reactivation of latent virus is generally clinically silent. HCMV infection, however, is associated with significant morbidity and mortality in the immunocompromised and chronic inflammatory diseases in the immunocompetent. In immunocompromised individuals (acquired immune deficiency syndrome and transplant patients, developing children (in utero), and cancer patients undergoing chemotherapy), HCMV infection increases morbidity and mortality. In those individuals with a normal immune system, HCMV infection is also associated with a risk of serious disease, as viral infection is now considered to be a strong risk factor for the development of various vascular diseases and to be associated with some types of tumor development. Intense research is currently being undertaken to better understand the mechanisms of viral pathogenesis that are briefly discussed in this chapter.

Shared mechanisms in stemness and carcinogenesis: lessons from oncogenic viruses

A rise in technologies for epigenetic reprogramming of cells to pluripotency, highlights the potential of understanding and manipulating cellular plasticity in unprecedented ways. Increasing evidence points to shared mechanisms between cellular reprogramming and the carcinogenic process, with the emerging possibility to harness these parallels in future therapeutics. In this review, we present a synopsis of recent work from oncogenic viruses which contributes to this body of knowledge, establishing a nexus between infection, cancer, and stemness.

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.

Human cytomegalovirus (HCMV) induces human endogenous retrovirus (HERV) transcription

BACKGROUND

Emerging evidence suggests that human cytomegalovirus (HCMV) is highly prevalent in tumours of different origin. This virus is implied to have oncogenic and oncomodulatory functions, through its ability to control host gene expression. Human endogenous retroviruses (HERV) are also frequently active in tumours of different origin, and are supposed to contribute as cofactors to cancer development. Due to the high prevalence of HCMV in several different tumours, and its ability to control host cell gene expression, we sought to define whether HCMV may affect HERV transcription.

FINDINGS

Infection of 3 established cancer cell lines, 2 primary glioblastoma cells, endothelial cells from 3 donors and monocytes from 4 donors with HCMV (strains VR 1814 or TB40/F) induced reverse transcriptase (RT) activity in all cells tested, but the response varied between donors. Both, gammaretrovirus-related class I elements HERV-T, HERV-W, HERV-F and ERV-9, and betaretrovirus-related class II elements HML-2 - 4 and HML-7 - 8, as well as spuma-virus related class III elements of the HERV-L group were up-regulated in response to HCMV infection in GliNS1 cells. Up-regulation of HERV activity was more pronounced in cells harbouring active HCMV infection, but was also induced by UV-inactivated virus. The effect was only slightly affected by ganciclovir treatment and was not controlled by the IE72 or IE86 HCMV genes.

CONCLUSIONS

Within this brief report we show that HCMV infection induces HERV transcriptional activity in different cell types.

High prevalence of HCMV and viral load in tumor tissues and peripheral blood of glioblastoma multiforme patients

Glioblastoma multiforme is the most prevalent and malignant tumor of the central nervous system. In the last few years, accumulating evidence has suggested an association between human cytomegalovirus (HCMV) infection and glioblastoma multiforme. In this study, tumor tissues and peripheral blood of patients with glioblastoma multiforme were examined for the presence of HCMV DNA. Twenty-two fresh surgical brain specimens and 20 peripheral blood samples were analyzed by real-time PCR (qPCR) and hemi-nested PCR (nPCR) for the presence of pp65 and (glycoprotein B) gB viral genomic regions, respectively. HCMV DNA was detected in the majority of the tumor samples analyzed (95% by qPCR and 91% by nPCR). About half of the patients with tumors positive for HCMV also had detectable viral DNA in their peripheral blood (47% by qPCR and 61% by nPCR). Genome copy numbers were determined and in the majority of the tumor samples cellular DNA outnumbers viral DNA (average of 1 infected cell in 33 cells). The gB genotypes were determined in HCMV-positive samples and gB2 was the most prevalent genotype in the tumor and blood samples. The results show a high prevalence of HCMV in glioblastoma multiforme samples reinforcing a possible association between HCMV infection and tumor development.

The tiers and dimensions of evasion of the type I interferon response by human cytomegalovirus

Human cytomegalovirus (HCMV) is a member of the β-herpesvirus family that invariably occupies hosts for life despite a consistent multi-pronged antiviral immune response that targets the infection. This persistence is enabled by the large viral genome that encodes factors conferring a wide assortment of sophisticated, often redundant phenotypes that disable or otherwise manipulate impactful immune effector processes. The type I interferon system represents a first line of host defense against infecting viruses. The physiological reactions induced by secreted interferon act to effectively block replication of a broad spectrum of virus types, including HCMV. As such, the virus must exhibit counteractive mechanisms to these responses that involve their inhibition, tolerance, or re-purposing. The goal of this review is to describe the impact of the type I interferon system on HCMV replication and to showcase the number and diversity of strategies employed by the virus that allow infection of hosts in the presence of interferon-dependent activity.

Human cytomegalovirus immediate early proteins promote degradation of connexin 43 and disrupt gap junction communication: implications for a role in gliomagenesis

A lack of gap junctional intercellular communication (GJIC) is common in cancer. Many oncogenic viruses have been shown to downregulate the junctional protein connexin 43 (Cx43) and reduce GJIC. Human cytomegalovirus (HCMV) is a ubiquitous, species-specific betaherpesvirus that establishes life-long latency after primary infection. It encodes two viral gene products, immediate early (IE) proteins IE1 and IE2, which are crucial in viral replication and pathogenesis of many diseases. Emerging evidence demonstrates that HCMV DNA and proteins are highly prevalent in glioblastoma multiforme (GBM) and in other tumors, but HCMV's role in tumorigenesis remains obscure. In the present study, we examined the effects of HCMV infection on Cx43 expression and GJIC as well as the viral mechanism mediating the effects in human GBM cells and tissue samples. We found that HCMV downregulated Cx43 protein, resulting in disruption of functional GJIC as assayed by fluorescent dye transfer assay. We show that both HCMV-IE72 and IE86 mediate downregulation of Cx43 by silencing RNA targeting either IE72 or IE86 coupled with ganciclovir. This finding was further validated by transfection with expression vectors encoding IE72 or IE86, and we show that viral-mediated Cx43 depletion involved proteasomal degradation. Importantly, we also observed that the Cx43 protein levels and IE staining correlated inversely in 10 human GBM tissue specimens. Thus, HCMV regulates Cx43 expression and GJIC, which may contribute to gliomagenesis.

Frequent detection of human cytomegalovirus in neuroblastoma: a novel therapeutic target?

Neuroblastoma is the most common and deadly tumor of childhood, where new therapy options for patients with high-risk disease are highly warranted. Human cytomegalovirus (HCMV) is prevalent in the human population and has recently been implicated in different cancer forms where it may provide mechanisms for oncogenic transformation, oncomodulation and tumor cell immune evasion. Here we show that the majority of primary neuroblastomas and neuroblastoma cell lines are infected with HCMV. Our analysis show that HCMV immediate-early protein was expressed in 100% of 36 primary neuroblastoma samples, and HCMV late protein was expressed in 92%. However, no infectious virus was detected in primary neuroblastoma tissue extracts. Remarkably, all six human neuroblastoma cell lines investigated contained CMV DNA and expressed HCMV proteins. HCMV proteins were expressed in neuroblastoma cells expressing the proposed stem cell markers CD133 and CD44. When engrafted into NMRI nu/nu mice, human neuroblastoma cells expressed HCMV DNA, RNA and proteins but did not produce infectious virus. The HCMV-specific antiviral drug valganciclovir significantly reduced viral protein expression and cell growth both in vitro and in vivo. These findings indicate that HCMV is important for the pathogenesis of neuroblastoma and that anti-viral therapy may be a novel adjuvant treatment option for children with neuroblastoma.

Cytomegalovirus pp71 protein is expressed in human glioblastoma and promotes pro-angiogenic signaling by activation of stem cell factor

Glioblastoma multiforme (GBM) is a highly malignant primary central nervous system neoplasm characterized by tumor cell invasion, robust angiogenesis, and a mean survival of 15 months. Human cytomegalovirus (HCMV) infection is present in >90% of GBMs, although the role the virus plays in GBM pathogenesis is unclear. We report here that HCMV pp71, a viral protein previously shown to promote cell cycle progression, is present in a majority of human GBMs and is preferentially expressed in the CD133+, cancer stem-like cell population. Overexpression of pp71 in adult neural precursor cells resulted in potent induction of stem cell factor (SCF), an important pro-angiogenic factor in GBM. Using double immunofluorescence, we demonstrate in situ co-localization of pp71 and SCF in clinical GBM specimens. pp71 overexpression in both normal and transformed glial cells increased SCF secretion and this effect was specific, since siRNA mediated knockdown of pp71 or treatment with the antiviral drug cidofovir resulted in decreased expression and secretion of SCF by HCMV-infected cells. pp71- induced upregulation of SCF resulted in downstream activation of its putative endothelial cell receptor, c-kit, and angiogenesis as measured by increased capillary tube formation in vitro. We demonstrate that pp71 induces a pro-inflammatory response via activation of NFΚB signaling which drives SCF expression. Furthermore, we show that pp71 levels and NFKB activation are selectively augmented in the mesenchymal subtype of human GBMs, characterized by worst patient outcome, suggesting that HCMV pp71-induced paracrine signaling may contribute to the aggressive phenotype of this human malignancy.

Pattern of the epitope-specific IgG/IgM response against human cytomegalovirus in patients with multiple myeloma

Human cytomegalovirus (HCMV) is a member of the herpesvirus family and represents a major human pathogen causing severe disease in newborns and immunocompromised patients, e.g., organ transplant recipients and patients with AIDS. One characteristic of herpesviruses is their ability to establish lifelong latency in their hosts; thus, reactivation during immunosuppression leads to recurrent episodes of disease. In several recent reports, it has been shown that HCMV infection may occur in patients with malignancy. This study focused on HCMV infection in patients with multiple myeloma (MM). In order to determine the IgM and IgG humoral immune response, sera from MM patients and healthy donors were analyzed with an accredited immunoblot test, and the IgM response was analyzed with an accredited enzyme-linked immunosorbent assay. A response against HCMV was detected in 80% of the MM patients. While the IgG pattern varied in each patient, the most prominent IgM response was against the tegument protein pp150 and two nonstructural proteins, the processivity factor (pUL44) and the single-stranded DNA binding protein (pUL57). An IgG avidity test revealed that 4 out of 20 MM patients had a fresh infection and 2 MM patients had a recent infection. The combination of IgG avidity and the IgM pattern will be a useful tool for reliable clinical diagnostics concerning HCMV and for application of early therapy for those MM patients suffering from a high viral load.

When Aging Reaches CD4+ T-Cells: Phenotypic and Functional Changes

Beyond midlife, the immune system shows aging features and its defensive capability becomes impaired, by a process known as immunosenescence that involves many changes in the innate and adaptive responses. Innate immunity seems to be better preserved globally, while the adaptive immune response exhibits profound age-dependent modifications. Elderly people display a decline in numbers of naïve T-cells in peripheral blood and lymphoid tissues, while, in contrast, their proportion of highly differentiated effector and memory T-cells, such as the CD28^null T-cells, increases markedly. Naïve and memory CD4+ T-cells constitute a highly dynamic system with constant homeostatic and antigen-driven proliferation, influx, and loss of T-cells. Thymic activity dwindles with age and essentially ceases in the later decades of life, severely constraining the generation of new T-cells. Homeostatic control mechanisms are very effective at maintaining a large and diverse subset of naïve CD4+ T-cells throughout life, but although later than in CD8 + T-cell compartment, these mechanisms ultimately fail with age.