Mitochondrial DNA Repair through OGG1 Activity Attenuates Breast Cancer Progression and Metastasis

Production of mitochondrial reactive oxygen species and integrity of mitochondrial DNA (mtDNA) are crucial in breast cancer progression and metastasis. Therefore, we evaluated the role of mtDNA damage in breast cancer by genetically modulating the DNA repair enzyme 8-oxoguanine DNA glycosylase (OGG1) in the PyMT transgenic mouse model of mammary tumorigenesis. We generated mice lacking OGG1 (KO), mice overexpressing human OGG1 subunit 1alpha in mitochondria (Tg), and mice simultaneously lacking OGG1 and overexpressing human OGG1 subunit 1alpha in mitochondria (KO/Tg). We found that Tg and KO/Tg mice developed significantly smaller tumors than KO and wildtype mice after 16 weeks. Histological analysis revealed a roughly two-fold decrease in the incidence of lung metastases in Tg mice (33.3%) compared to wildtype mice (62.5%). Furthermore, lungs from Tg mice exhibited nearly a 15-fold decrease in the average number of metastatic foci compared to WT mice (p