Association of mitochondrial DNA mutations with Chinese esophageal squamous cell carcinomas (ESCC) by analyzing the whole mitochondrial DNA genomes

Mitochondrial DNA (mtDNA) mutations play crucial roles in the pathogenesis and progression of human malignancies. However, studies reporting associations between mitochondrial DNA mutations and risks of esophageal squamous cell carcinomas (ESCC) have seldom been reported. In this study, we sequenced 22 cancer tissues and the corresponding adjacent non-cancerous tissues collected from 11 ESCC patients. The mtDNA sequence length ranged from 16,568-16,579 bp. The results indicated that there are several sensitive sites in the 22 mtDNAs, especially in the control region (CR) and protein-coding genes (PCGs). The 22 mtDNA sequences were classified into haplogroups B, D, G, M, and Z; haplogroup D and haplogroup M were shared within a wider distribution, but haplotype G was found only in two samples and all the patients showed the southern of East Asia or Northern East Asian haplogroups, the number and ratio of patients showed the southern of East Asia or Southeast Asia characters are equal. Our findings suggest that mtDNA haplogroups D and M might be potential risks for ESCC. In addition, our results suggest that mtDNA haplogroups and some sensitive sites confer genetic susceptibility to ESCC and they can serve as potential biomarkers for clinical diagnosis.