Comprehensive scanning of somatic mitochondrial DNA mutations in breast cancer.

To investigate the role of mitochondrial DNA (mtDNA) in tumorigenesis, a temporal temperature gradient gel electrophoresis method was used to analyze the somatic mtDNA mutations in breast cancer. The entire mitochondrial genomes in 19 tumor samples and paired normal tissues from the same patients were amplified using 32 pairs of overlapping primers. DNA fragments showing different banding patterns between normal and tumor mtDNA were sequenced to identify the mutations. Fourteen of the 19 tumors (74%) displayed at least one somatic mtDNA mutation. Twenty-seven somatic mutations were found, and 22 of them occurred in the D loop region. This study represents the most comprehensive mtDNA mutational analysis in breast cancer.