Mutations and polymorphisms in mitochondrial DNA in head and neck cancer cell lines

Changes in mitochondrial DNA have been reported in cancer cells. Since little information exists regarding mt DNA mutations in head and neck, the present study focused on ten head and neck cancer cell lines in the attempt to detect alterations in the ND4 gene sequence. DNA was extracted from 10 head and neck squamous cell carcinoma lines from 9 patients. MtDNA sequences were compared in normal and tumour cell line DNA. In ten head and neck squamous cell carcinoma cell lines, 8 somatic mutations and 5 polymorphisms of the mitochondrial gene for ND4 were found. All 5 polymorphisms were silent. Of the 8 somatic mutations, 3 altered the amino acid sequence suggesting a possible effect on enzyme function. The mitochondrial mutations and polymorphisms found demonstrated that these can serve as clonal markers for individual cell lines and demonstrate that the mitochondrial genome remains stable in the cell lines during in vitro culture.