High copy number of mitochondrial DNA (mtDNA) predicts good prognosis in glioma patients.

Alterations in mitochondrial DNA (mtDNA) copy number have been widely identified in many types of human cancers and are considered a common cancer hallmark. However, the prognostic value of altered mtDNA content in gliomas remains largely unknown. The aim of this study was to investigate mtDNA copy number in a cohort of gliomas (n = 124) and non-neoplastic brain tissues (control subjects; n = 27) and to explore the association between variable mtDNA content and clinical outcomes in glioma patients. Using real-time quantitative PCR assay, we demonstrated that glioma patients had an increased mtDNA content as compared with control subjects. In addition, our data showed that increased mtDNA copy number was significantly negatively associated with tumor grade, recurrence and cancer-related death, whereas there was a significantly positively relationship between increased mtDNA content and seizures. More importantly, increased mtDNA content were closely relevant to longer survival in glioma patients. Taken together, our data provide the strong evidences that high copy number of mtDNA may be a useful good prognostic factor in glioma patients.