Elevated level of 8-oxo-7,8-dihydro-2'-deoxyguanosine in leukocytes of BRCA1 mutation carriers compared to healthy controls.

Carriers of BRCA1 mutation face highly increased risk of breast and ovarian cancer and some studies with cell culture suggest that the encoded protein may be involved in oxidatively damaged DNA repair. However, no studies concerning a possible link between oxidatively damaged DNA and BRCA1 deficiency have been conducted with the mutations carriers. Therefore, to assess an involvement of BRCA in oxidative damage to DNA in the present study a broad spectrum of parameters reflecting oxidative stress/DNA damage were analyzed in 3 subject groups; (i) carriers of BRCA1 mutations without symptoms of the disease; (ii) patients with breast or ovarian cancer with the mutations and (iii) the group of healthy subjects recruited from among close relatives of the group of carriers without symptoms of the disease. We found that the endogenous levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in leukocytes DNA and excretion rates of urinary 8-oxodG were significantly higher in the cancer patients than in the healthy carriers. Similarly, to the cancer patient group, 8-oxodG level in leukocytes DNA is significantly higher in the carriers group in comparison with control group. That the control group comprised close relatives of the carriers gives further credit to our finding. Since we did not observe substantial differences in the analyzed markers of oxidative stress between the controls and the carriers, the observed increase in the level may be a result of a deficiency in the repair of 8-oxodG.