Mitochondrial DNA D-Loop mutation in malignancy

Studies have shown the presence of mitochondrial (mt) deoxyribonucelic acid (mtDNA) mutations in primary cancers. mtDNA is constantly subject to reactive oxygen species and does not have any protective proteins or introns unlike nuclear DNA. Hence, mtDNA is more prone to mutations and alterations. Furthermore, wild type and mutated mitochondrial DNA can coexist in a single cell. This phenomenon is known as heteroplasmy. Mutated DNA may have a replicative advantage, resulting in the increased proliferation of cells which can lead to cancer. mtDNA consists of a non-coding, triplex structure known as the displacement loop (D-loop) region. Mutations in the D-loop region have been associated with tumours. Studies have indicated that the D-loop region plays a significant role in cancer progression. The exact role of specific D-loop mutations in different malignancies is yet to be discovered. This study provides a comprehensive summary of D-loop region mutations associated with cancer. This review offers a perspective on D-loop region mutations, their effects on tumour progression and the association of the Dloop mutations with patient prognosis.