Detection of human Papilloma virus DNA in a subset of glioblastoma samples

BACKGROUND: Glioblastoma Multiforme (GBM) is the most common malignant brain tumor in adults, but its aetiology remains unknown. Recent reports have demonstrated the presence of neurotropic viruses in glioma samples, leading to the hypothesis that viral infection could be involved in tumorigenesis. AIM OF THE STUDY: To assess the burden of HPV infection in a cohort of malignant gliomas. MATERIALS AND METHODS: Seventy-one fresh frozen tumour samples of 62 glioblastomas and 9 grade III astrocytomas have been retrospectively analyzed. The presence of HPV genome in tumour DNA was assessed by MY/GP nested PCR. PCR products were sequenced with Sanger technology in order to define the viral genotype involved in the infection. A PCR with genotype-specific primer sets was carried out as confirmation of the infection. RESULTS: Viral DNA was detected after PCR in 8 (11%) cases. According to our previous studies both low- and high risk genotypes were isolated. Sequencing analysis showed that HPV16 genome was present in 4 (50%) infected samples whereas the remaining 4 resulted positive to HPV6. All positive cases were diagnosed as primary glioblastomas, and no positivity was found in lower grade glioma samples. Median overall survival did not significantly differ between HPV-positive and HPV-negative patients. CONCLUSIONS: The presence of HPV in high grade glioma specimens deserves further investigation. The analysis of a large cohort of tumors, along with in vitro studies on glioblastoma cell lines, will allow to better clarify the role of HPV in gliomagenesis and assess its potential use as a prognostic factor.