Evidence of association of human papillomavirus with prognosis worsening in glioblastoma multiforme

Association between viral infections and glioma risk: a two-sample bidirectional Mendelian randomization analysis

BACKGROUND

Glioma is one of the leading types of brain tumor, but few etiologic factors of primary glioma have been identified. Previous observational research has shown an association between viral infection and glioma risk. In this study, we used Mendelian randomization (MR) analysis to explore the direction and magnitude of the causal relationship between viral infection and glioma.

METHODS

We conducted a two-sample bidirectional MR analysis using genome-wide association study (GWAS) data. Summary statistics data of glioma were collected from the largest meta-analysis GWAS, involving 12,488 cases and 18,169 controls. Single-nucleotide polymorphisms (SNPs) associated with exposures were used as instrumental variables to estimate the causal relationship between glioma and twelve types of viral infections from corresponding GWAS data. In addition, sensitivity analyses were performed.

RESULTS

After correcting for multiple tests and sensitivity analysis, we detected that genetically predicted herpes zoster (caused by Varicella zoster virus (VZV) infection) significantly decreased risk of low-grade glioma (LGG) development (OR = 0.85, 95% CI: 0.76-0.96, P = 0.01, FDR = 0.04). No causal effects of the other eleven viral infections on glioma and reverse causality were detected.

CONCLUSIONS

This is one of the first and largest studies in this field. We show robust evidence supporting that genetically predicted herpes zoster caused by VZV infection reduces risk of LGG. The findings of our research advance understanding of the etiology of glioma.

Analysis of regulatory sequences in exosomal DNA of NANOGP8

Exosomes participate in intercellular communication by transporting functionally active molecules. Such cargo from the original cells comprising proteins, micro-RNA, mRNA, single-stranded (ssDNA) and double-stranded DNA (dsDNA) molecules pleiotropically transforms the target cells. Although cancer cells secrete exosomes carrying a significant level of DNA capable of modulating oncogene expression in a recipient cell, the regulatory mechanism is unknown. We have previously reported that cancer cells produce exosomes containing NANOGP8 DNA. NANOGP8 is an oncogenic paralog of embryonic stem cell transcription factor NANOG and does not express in cells since it is a pseudogene. However, in this study, we evaluated NANOGP8 expression in glioblastoma multiforme (GBM) tissue from a surgically removed brain tumor of a patient. Significantly higher NANOGP8 transcription was observed in GBM cancer stem cells (CSCs) than in GBM cancer cells or neural stem cells (NSCs), despite identical sequences of NANOGP8-upstream genomic region in all the cell lines. This finding suggests that upstream genomic sequences of NANOGP8 may have environment-dependent promoter activity. We also found that the regulatory sequences upstream of exosomal NANOGP8 GBM DNA contain multiple core promoter elements, transcription factor binding sites, and segments of human viruses known for their oncogenic role. The exosomal sequence of NANOGP8-upstream GBM DNA is different from corresponding genomic sequences in CSCs, cancer cells, and NSCs as well as from the sequences reported by NCBI. These sequence dissimilarities suggest that exosomal NANOGP8 GBM DNA may not be a part of the genomic DNA. Exosomes possibly acquire this DNA from other sources where it is synthesized by an unknown mechanism. The significance of exosome-bestowed regulatory elements in the transcription of promoter-less retrogene such as NANOGP8 remains to be determined.

HPV-Associated Breast Cancer: Myth or Fact?

Some estimates place the proportion of human malignancies attributable to viruses at between 15 and 20 percent. Viruses including the human papillomavirus are considered an interesting but controversial etiological risk factor for breast cancer. HPV infection is anticipated to be an early trigger in breast cancer carcinogenesis, followed by cumulative alterations over time ("hit and run" mechanism) through synergy with other environmental factors. The association between HPV and breast cancer has not yet been verified. There are very conflicting data on the presence of HPV DNA in breast cancer samples, and we lack a clarified, exact mode of HPV transmission to the breast. In our review article we analyzed the up-to-date knowledge about the association of HPV and breast cancer. Furthermore, we summarized the available original research published since 2010. In conclusion, the complexity and inconsistency of the available results together with the relatively low prevalence of HPV infection requires extensive research with much larger studies and exact and unified diagnostic methods are required to better understand the role of the HPV in breast carcinogenesis.

Viral oncogenesis in tumours of the central nervous system: reality or random association? A retrospective study on archived material

Central nervous system (CNS) tumours have devastating effects and are recurrent, with dismal prognosis (gliomas) or life‐threatening by the compression effect (meningiomas). This disease's aetiology remains debatable. Over the last decade, the hypothesis that human viruses may be implicated in these tumours has been proposed. In this study, our aim is to examine the presence of 11 viruses in the most frequent CNS primary tumours. Using polymerase chain reaction (PCR), we assessed the viral presence in archived, paraffin‐embedded tumour tissues from 114 patients with glioma and meningioma and in the brain tissue from 40 controls lacking tumour pathology. We focused on candidate neuro‐oncogenic types (herpesviridae and polyomaviruses) and on human papillomavirus (HPV). HPV presence, for which involvement in these tumours was hardly investigated, was found to be associated with both tumour categories compared with controls (glioma, p = 0.032; meningioma, p = 0.032), whereas the presence of the neuro‐oncogenic viruses was found in a negligible number of both categories, suggesting a lack of association with the tumour presence. Moreover, our study reveals a positive correlation between HPV presence and glioma malignancy, and a negative correlation with meningioma grading. Our results suggest that the presence of HPV seems to be significantly associated with primary tumours of the CNS and its meninges.

Virome assembly and annotation in brain tissue based on next-generation sequencing

The glioblastoma multiforme (GBM) is one of the deadliest tumors. It has been speculated that virus plays a role in GBM but the evidences are controversy. Published researches are mainly limited to studies on the presence of human cytomegalovirus (HCMV) in GBM. No comprehensive assessment of the brain virome, the collection of viral material in the brain, based on recently sequenced data has been performed. Here, we characterized the virome from 111 GBM samples and 57 normal brain samples from eight projects in the SRA database by a tested and comprehensive assembly approach. The annotation of the assembled contigs showed that most viral sequences in the brain belong to the viral family Retroviridae. In some GBM samples, we also detected full genome sequence of a novel picornavirus recently discovered in invertebrates. Unlike previous reports, our study did not detect herpes virus such as HCMV in GBM from the data we used. However, some contigs that cannot be annotated with any known genes exhibited antibody epitopes in their sequences. These findings provide several avenues for potential cancer therapy: the newly discovered picornavirus could be a starting point to engineer novel oncolytic virus; and the exhibited antibody epitopes could be a source to explore potential drug targets for immune cancer therapy. By characterizing the virosphere in GBM and normal brain at a global level, the results from this study strengthen the link between GBM and viral infection which warrants the further investigation.

Investigation of Human Cytomegalovirus and Human Papillomavirus in Glioma

The study investigated the human cytomegalovirus (HCMV) and human papillomavirus (HPV) in gliomas. A retrospective study was conducted on 112 samples. HCMV was investigated by PCR, in situ hybridization (ISH) and immunohistochemistry. HPV was tested by PCR and DNA ISH. HCMV was identified in 60 gliomas, including 55 GBM. However, RNA ISH and immunohistochemistry failed to detect HCMV positivity. HPV was identified in 44 GBM. No significant relationship was identified between HCMV and HPV and tumour characteristics (p > 0.05). Our findings support the HCMV and HPV presence in gliomas. Further assays are required to more explore the potential efficient antiviral management.

Involvement of Kallikrein-Related Peptidases in Nervous System Disorders

Kallikrein-related peptidases (KLKs) are a family of serine proteases that when dysregulated may contribute to neuroinflammation and neurodegeneration. In the present review article, we describe what is known about their physiological and pathological roles with an emphasis on KLK6 and KLK8, two KLKs that are highly expressed in the adult central nervous system (CNS). Altered expression and activity of KLK6 have been linked to brain physiology and the development of multiple sclerosis. On the other hand, altered levels of KLK6 in the brain and serum of people affected by Alzheimer's disease and Parkinson's disease have been documented, pointing out to its function in amyloid metabolism and development of synucleinopathies. People who have structural genetic variants of KLK8 can suffer mental illnesses such as intellectual and learning disabilities, seizures, and autism. Increased expression of KLK8 has also been implicated in schizophrenia, bipolar disorder, and depression. Also, we discuss the possible link that exists between KLKs activity and certain viral infections that can affect the nervous system. Although little is known about the exact mechanisms that mediate KLKs function and their participation in neuroinflammatory and neurodegenerative disorders will open a new field to develop novel therapies to modulate their levels and/or activity and their harmful effects on the CNS.

Viral infection and glioma: a meta-analysis of prognosis

Background

Glioma is the most common primary brain tumor, occurring due to the carcinogenesis of glial cells in the brain and spinal cord. Many aspects of the mechanism of its tumorigenesis remain unknown. The relationship between viral infection and glioma is one of the most important research aspects in this field. Currently, there is a lack of systematic reviews and meta-analyses to evaluate the effect of viral infection on the prognosis of glioma patients. The purpose of this study was to evaluate the relationship between viral infection and the prognosis of glioma patients, aimed at evaluating the prognostic value of the detection of viral infection.

Methods

Through careful and comprehensive retrieval of results from the PubMed, Embase, and Cochrane databases, eligible articles were selected strictly according to the inclusion and exclusion criteria. The regional sources, detection methods, detection indicators, patient survival, and other data from the samples in the papers were extracted, and the integrated analysis was conducted using Stata 15.1. We conducted a subgroup analysis of the relationship between the degree of infection and prognosis in cytomegalovirus (CMV) patients.

Results

A total of 11 studies were included in the analysis. Among them, 7 studies involved the relationship between CMV infection and the prognosis of patients with glioma, 2 studies involved human papillomavirus (HPV), 2 studies involved human herpesvirus-6 (HHV-6), and one study involved simian virus 40 (SV40), woolly monkey sarcoma virus (WMSV) and human endogenous retrovirus K113 (HERV-K113). In the CMV study, the pooled Hazard ratio (HR) of Overall survival (OS) was 1.024 (CI: 0.698–1.501), with a P value of 0.905. The pooled HR of Progression free survival (PFS) was 1.067 (CI: 0.770–1.478), with a P value of 0.697. The pooled HR value of low-degree infection versus high-degree infection was 1.476 (CI: 0.799–2.727), with a P value of 0.213. In the HPV study, the pooled HR of OS was 1.467 (CI: 0.552–3.901), with a P value of 0.443.

Conclusion

CMV infection has no significant effect on the prognosis of glioma patients. Using the IEA as the detection index, the degree of CMV infection was found to have a significant impact on the prognosis of glioma patients; it was not found to possess a significant prognostic value after the integration of different indicators. Neither HPV nor HHV-6 infection has a significant effect on the prognosis of glioma patients. SV40 and WMSV infection are associated with poor prognosis in patients with low-grade glioma.

Trial Registration

This meta-analysis registered in https://www.crd.york.ac.uk/PROSPERO/, PROSPERO ID: CRD42019127648.

Investigation of simian virus 40 (SV40) and human JC, BK, MC, KI, and WU polyomaviruses in glioma

The gliomagenesis remains not fully established and their etiological factors still remain obscure. Polyomaviruses were detected and involved in several human tumors. Their potential implication in gliomas has been not yet surveyed in Africa and Arab World. Herein, we investigated the prevalence of six polyomaviruses (SV40, JCPyV, BKPyV, MCPyV, KIPyV, and WUPyV) in 112 gliomas from Tunisian patients. The DNA sequences of polyomaviruses were examined by PCR assays. Viral infection was confirmed by DNA in situ hybridization (ISH) and/or immunohistochemistry (IHC). The relationships between polyomavirus infection and tumor features were evaluated. Specific SV40 Tag, viral regulatory, and VP1 regions were identified in 12 GBM (10.7%). DNA ISH targeting the whole SV40 genome and SV40 Tag IHC confirmed the PCR findings. Five gliomas yielded JCPyV positivity by PCR and DNA ISH (2.7%). However, no BKPyV, KIPyV, and WUPyV DNA sequences were identified in all samples. MCPyV DNA was identified in 30 gliomas (26.8%). For GBM samples, MCPyV was significantly related to patient age (p = 0.037), tumor recurrence (p = 0.024), and SV40 (p = 0.045) infection. No further significant association was identified with the remaining tumor features (p > 0.05) and patient survival (Log Rank, p > 0.05). Our study indicates the presence of SV40, JCPyV, and MCPyV DNA in Tunisian gliomas. Further investigations are required to more elucidate the potential involvement of polyomaviruses in these destructive malignancies.

The influence of patient sex on clinical approaches to malignant glioma

Gliomas are tumors that originate from the glial tissue, thus involving the central nervous system with varying degrees of malignancy. The most aggressive and frequent form is glioblastoma multiforme, a disease characterized by resistance to therapies, frequent recurrences, and extremely poor median survival time. Data on overall glioma case studies demonstrate clear sex disparities regarding incidence, prognosis, drug toxicity, clinical outcome, and, recently, prediction of therapeutic response. In this study, we analyze data in the literature regarding malignant glioma, mainly glioblastoma multiforme, focusing on epidemiological and clinical evaluations. Less discussed issues, such as the role of viral infections, energy metabolism, and predictive aspects concerning the possible use of dedicated therapeutic approaches for male or female patients, will be reported together with different estimated pathogenetic mechanisms underlying astrocyte transformation and glioma chemosensitivity. In this era, where personalized/precision medicine is the most important driver for targeted cancer therapies, the lines of evidence discussed herein strongly suggest that clinical approaches to malignant glioma should consider the patient's sex. Furthermore, retrospectively revising previous clinical studies considering patient sex as a crucial variable is recommended.

HPV DNA Associates With Breast Cancer Malignancy and It Is Transferred to Breast Cancer Stromal Cells by Extracellular Vesicles

A causal link between Human Papillomavirus (HPV) and breast cancer (BC) remains controversial. In spite of this, the observation that HPV DNA is over-represented in the Triple Negative (TN) BC has been reported. Here we remark the high prevalence of HPV DNA (44.4%) in aggressive BC subtypes (TN and HER2+) in a population of 273 Italian women and we convey the presence of HPV DNA in the epithelial and stromal compartments by in situ hybridization. As previously reported, we also found that serum derived-extracellular vesicles (EVs) from BC affected patients contain HPV DNA. Interestingly, in one TNBC patient, the same HPV DNA type was detected in the serum-derived EVs, cervical and BC tissue samples. Then, we report that HPV DNA can be transferred by EVs to recipient BC stromal cells that show an activated phenotype (e.g., CD44, IL6 expression) and an enhanced capability to sustain mammospheres (MS) formation. These data suggest that HPV DNA vehiculated by EVs is a potential trigger for BC niche aggressiveness.

Putative Role of Circulating Human Papillomavirus DNA in the Development of Primary Squamous Cell Carcinoma of the Middle Rectum: A Case Report

Here we present the case of a patient affected by rectal squamous cell carcinoma in which we demonstrated the presence of Human Papillomavirus (HPV) by a variety of techniques. Collectively, the virus was detected not only in the tumor but also in some regional lymph nodes and in non-neoplastic mucosa of the upper tract of large bowel. By contrast, it was not identifiable in its common sites of entry, namely oral and ano-genital region. We also found HPV DNA in the plasma-derived exosome. Next, by in vitro studies, we confirmed the capability of HPV DNA-positive exosomes, isolated from the supernatant of a HPV DNA positive cell line (CaSki), to transfer its DNA to human colon cancer and normal cell lines. In the stroma nearby the tumor mass we were able to demonstrate the presence of virus DNA in the stromal compartment, supporting its potential to be transferred from epithelial cells to the stromal ones. Thus, this case report favors the notion that human papillomavirus DNA can be vehiculated by exosomes in the blood of neoplastic patients and that it can be transferred, at least in vitro, to normal and neoplastic cells. Furthermore, we showed the presence of viral DNA and RNA in pluripotent stem cells of non-tumor tissue, suggesting that after viral integration (as demonstrated by p16 and RNA in situ hybridization positivity), stem cells might have been activated into cancer stem cells inducing neoplastic transformation of normal tissue through the inactivation of p53, p21, and Rb. It is conceivable that the virus has elicited its oncogenic effect in this specific site and not elsewhere, despite its wide anatomical distribution in the patient, for a local condition of immune suppression, as demonstrated by the increase of T-regulatory (CD4/CD25/FOXP3 positive) and T-exhausted (CD8/PD-1positive) lymphocytes and the M2 polarization (high CD163/CD68 ratio) of macrophages in the neoplastic microenvironment. It is noteworthy that our findings depicted a static picture of a long-lasting dynamic process that might evolve in the development of tumors in other anatomical sites.

Epstein-Barr Virus in Gliomas: Cause, Association, or Artifact?

Gliomas are the most common malignant brain tumors and account for around 60% of all primary central nervous system cancers. Glioblastoma multiforme (GBM) is a grade IV glioma associated with a poor outcome despite recent advances in chemotherapy. The etiology of gliomas is unknown, but neurotropic viruses including the Epstein–Barr virus (EBV) that is transmitted via salivary and genital fluids have been implicated recently. EBV is a member of the gamma herpes simplex family of DNA viruses that is known to cause infectious mononucleosis (glandular fever) and is strongly linked with the oncogenesis of several cancers, including B-cell lymphomas, nasopharyngeal, and gastric carcinomas. The fact that EBV is thought to be the causative agent for primary central nervous system (CNS) lymphomas in immune-deficient patients has led to its investigations in other brain tumors including gliomas. Here, we provide a review of the clinical literature pertaining to EBV in gliomas and discuss the possibilities of this virus being simply associative, causative, or even an experimental artifact. We searched the PubMed/MEDLINE databases using the following key words such as: glioma(s), glioblastoma multiforme, brain tumors/cancers, EBV, and neurotropic viruses. Our literature analysis indicates conflicting results on the presence and role of EBV in gliomas. Further comprehensive studies are needed to fully implicate EBV in gliomagenesis and oncomodulation. Understanding the role of EBV and other oncoviruses in the etiology of gliomas, would likely open up new avenues for the treatment and management of these, often fatal, CNS tumors.

Untangling the most probable role for vitamin D3 in autism

Recent studies indicate an important role for vitamin D3 in autism spectrum disorder (ASD), although its mechanism is not completely understood. The most puzzling aspect of ASD is that identical twins, who share identical DNA, do not have 100% concordance rates (∼88% for identical and ∼31% for fraternal twins). These findings provide major clues into the etiology: ASD must involve an environmental factor present in the prenatal milieu that both identical twins are not always exposed to because they do not always share it (i.e., placentas). Combined with the exponential increasing rates of ASD around the world, these observations suggest a contagious disease is probably transferred to the fetus via the placenta becoming infected by a cervical virus. Vitamin D3 boosts immune responses clearing viral infections and increases serotonin and estrogen brain levels. Here we review the different roles and untangle the most probable one vitamin D3 plays in ASD.

Liquid biopsy in the diagnosis of HPV DNA in breast lesions

AIM

HPV DNA has never been investigated in nipple discharges (ND) and serum-derived extracellular vesicles, although its presence has been reported in ductal lavage fluids and blood specimens.

MATERIALS & METHODS

We analyzed 50 ND, 22 serum-derived extracellular vesicles as well as 51 pathologic breast tissues for the presence of 16 HPV DNA types.

RESULTS

We show that the presence of HPV DNA in the ND is predictive of HPV DNA-positive breast lesions and that HPV DNA is more represented in intraductal papillomas. We also show the presence of HPV DNA in the serum-derived extracellular vesicles.

CONCLUSION

Our data supports the use of liquid biopsy to detect HPV DNA in breast pathology.

Focal Cortical Dysplasia: Gene Mutations, Cell Signaling, and Therapeutic Implications

Focal cortical dysplasias (FCDs) are malformations of cortical development (MCDs) that are highly associated with medication-resistant epilepsy and are the most common cause of neocortical epilepsy in children. FCDs are a heterogeneous group of developmental disorders caused by germline or somatic mutations that occur in genes regulating the PI3K/Akt/mTOR pathway-a key pathway in neuronal growth and migration. Accordingly, FCDs are characterized by abnormal cortical lamination, cell morphology (e.g., cytomegaly), and cellular polarity. In some FCD subtypes, balloon cells express proteins typically seen in neuroglial progenitor cells. Because recurrent intractable seizures are a common feature of FCDs, epileptogenic electrophysiological properties are also observed in addition to local inflammation. Here, we will summarize the current literature regarding FCDs, addressing the current classification system, histopathology, molecular genetics, electrophysiology, and transcriptome and cell signaling changes.

Detection of human cytomegalovirus in glioblastoma among Taiwanese subjects

The relationship between human cytomegalovirus (HCMV) and glioblastoma (GBM) has been debated for more than a decade. We investigated the presence of HCMV genes, RNA and protein in GBMs and their relationships with tumor progression. Results of quantitative PCR for HCMV UL73, nested PCR for HCMV UL144, in situ hybridization (ISH) for RNA transcript, and immunohistochemistry (IHC) for protein expression and their relationship to the prognosis of 116 patients with GBM were evaluated. Nine (7.8%) cases revealed a low concentration of HCMV UL73, and only 2 of the 9 (1.7%) cases showed consistent positivity on repeat PCR testing. HCMV UL144, ISH and IHC assays were all negative. The HCMV UL73 positive cases did not show significant difference in the clinicopathological characters including age, gender, Karnofsky performance status, extent of resection, bevacizumab treatment, isocitrate dehydrogenase 1 mutation, O⁶-methylguanine-DNA-methyltranferase status and Ki67 labeling index, and did not reveal prognostic significance. As only one HCMV gene was detected at low concentration in 7.8% of GBMs and there was no evidence of transcription, protein expression or prognostic impact, we cannot conclude a relationship between HCMV and GBM in Taiwanese patients.

Tumor characterization and stratification by integrated molecular profiles reveals essential pan-cancer features

BACKGROUND

Identification of tumor heterogeneity and genomic similarities across different cancer types is essential to the design of effective stratified treatments and for the discovery of treatments that can be extended to different types of tumors. However, systematic investigations on comprehensive molecular profiles have not been fully explored to achieve this goal.

RESULTS

Here, we performed a network-based integrative pan-cancer genomic analysis on >3000 samples from 12 cancer types to uncover novel stratifications among tumors. Our study not only revealed recurrently reported cross-cancer similarities, but also identified novel ones. The macro-scale stratification demonstrates strong clinical relevance and reveals consistent risk tendency among cancer types. The micro-scale stratification shows essential pan-cancer heterogeneity with subgroup-specific gene network characteristics and biological functions.

CONCLUSIONS

In summary, our comprehensive network-based pan-cancer stratification provides valuable information about inter- and intra- cancer stratification for patient clinical assessments and therapeutic strategies.

Identification of Human Papilloma Viruses in Atheromatous Coronary Artery Disease

Objective

To identify human papilloma viruses (HPV) in atheromatous coronary arteries.

Background

Atheromatous arterial disease is primarily an initial inflammatory response to unknown stimuli. The crucial question is “what causes the initial inflammation in atheromatous disease?” HPV infections may be relevant as US women with vaginal, high risk for cancer, HPV infections, are at up to threefold increased risk of cardiovascular disease as compared with vaginal HPV-negative women. These studies did not include analyses of HPV in atheromatous coronary arteries.

Methods

Atheromatous coronary arteries were identified and collected from 20 deceased donors. Polymerase Chain Reaction techniques were used to identify HPV gene sequences. Immunohistochemistry methods were used to identify HPV E7 proteins.

Results

HPV types 16 and 18 were identified in 11 (55%) of 20 specimens. HPV E7 protein was identified in 10 (50%) of 20 specimens. Positive and negative HPV identification and HPV E7 expression in coronary smooth muscle cells were significantly correlated (cc = 0.503, p = 0.024). The HPV E7 proteins were expressed in smooth muscle cells and plasma cells, foam cells, and macrophages located in the atheromatous plaque. HPV E7 proteins were not expressed in infiltrating lymph cells.

Conclusion

HPV gene sequences were identified in 55% of atheromatous coronary arteries and may have a role in coronary artery disease.

Prevalence of human cytomegalovirus, polyomaviruses, and oncogenic viruses in glioblastoma among Japanese subjects

Background

The association between human cytomegalovirus (HCMV) and glioblastoma multiforme (GBM) is becoming a new concept. However, information on the geographic variability of HCMV prevalence in GBM remains scarce. Moreover, the potential roles of various viruses, such as polyomaviruses and oncogenic viruses, in gliomagenesis remain unclear. Our aim was to investigate the prevalence of HCMV in GBM among Japanese patients. Furthermore, this was the first study that evaluated infection with four new human polyomaviruses in GBMs. This study also provided the first data on the detection of human papillomavirus (HPV) in GBM in the Eastern world.

Methods

We measured the number of various viral genomes in GBM samples from 39 Japanese patients using real-time quantitative PCR. The tested viruses included HCMV, Merkel cell polyomavirus, human polyomavirus (HPyV) 6, HPyV7, HPyV9, Epstein–Barr virus, human herpesvirus 8, and HPV. Our quantitative PCR analysis led to the detection of eight copies of the HCMV DNA mixed with DNA extracted from 10⁴ HCMV-negative cells. The presence of HCMV and HPV genomes was also assessed by nested PCR. Immunohistochemical study was also carried out to detect HPV-derived protein in GBM tissues.

Results

The viral DNAs were not detectable, with the exception of HPV, which was present in eight out of 39 (21%) GBMs. All HPV-positive cases harbored high-risk-type HPV (HPV16 and HPV18). Moreover, the HPV major capsid protein was detected in GBM tumor cells.

Conclusions

In contrast with previous reports from Caucasian patients, we did not obtain direct evidence in support of the association between HCMV and GBM. However, high-risk-type HPV infection may play a potential etiological role in gliomagenesis in a subset of patients. These findings should prompt further worldwide epidemiological studies aimed at defining the pathogenicity of virus-associated GBM.