Frequent mutations in the mitochondrial control region DNA in breast tissue

It has been suggested that the extent of mitochondrial DNA mutations might be useful in the prognosis of cancer outcome and/or the response to certain therapies. In order to investigate whether a high incidence of mutations exists in mitochondrial DNA of breast cancer tissues, we screened three regions of the mitochondrial genome by PCR amplification followed by DNA sequence analysis. Laser capture microdissection was used to isolate pure populations of both tumor cells and normal cells from paraffin embedded specimens. DNA isolated from these cells was used to amplify hypervariable regions HV1 and HV2 and the D-loop region. We found a high rate of mutation in the cancer cell DNA but also found the mutation rate was high in the corresponding normal DNA as well. While no correlations to any clinical parameters could be drawn from this study, the variation from patient to patient suggests that clinical implications might be established on examination of a larger number of samples.