Mitochondrial Deoxyribonucleic Acid Copy Number Elevation As a Predictor for Extended Survival and Favorable Outcomes in High-Grade Brain Tumor Patients: A Malaysian Study

Abstract

Background: Investigating the role of mitochondrial DNA (mtDNA) alterations and their impact on brain tumor progression remains a significant focus in cancer research. The research aimed to explore the specific contributions of mtDNA copy number changes and their correlations with patient survival, large mtDNA deletions, and TFAM mutations in brain tumor patients. Methods: A total of 41 patients with confirmed brain tumors underwent DNA extraction from both tumor tissues and blood samples. The relative mtDNA copy number in comparison to the nuclear genome was quantified using quantitative real-time polymerase chain reaction (qRT-PCR). Long-range PCR assessed large-scale mtDNA deletions, and Sanger sequencing was applied to detect exon 4 TFAM mutations. Results: Analysis revealed significantly increased mtDNA copy numbers in brain tumor tissues (80.5%) compared to matched blood samples ( P < .001). Median delta Ct (∆Ct) values were 7.35 in cancerous tissues and 11.81 in blood ( P < .001), with median relative mtDNA content of 0.0123 and 0.0006, respectively ( P < .001). Patients with higher mtDNA copy numbers experienced longer overall survival periods ( P = .045) and notably favorable outcomes, particularly in high-grade tumor cases ( P = .016). Furthermore, a single-nucleotide deletion was identified in exon 4 of TFAM in a patient with glioblastoma IV, while no large-scale mtDNA deletions were found in brain tumor patients. Conclusion: Our study strongly supports the role of increased mtDNA copy numbers as a reliable predictor for improved survival and positive outcomes in high-grade brain tumor patients.