Estrogen treatment inhibits OGG1 expression. (A) Real-time PCR data are presented to show expression of OGG1 mRNA in mammary tumors and in mammary tissues of rats treated with E2 for 7 and 240 days. These data are reported as an average of fold change values obtained from at least 5 different animals ± SEM, compared to respective age-matched control mammary tissues. (B) OGG1 mRNA expression levels in MCF-10A and T47D cells treated with E2 (50 nM) for 6 and 48 h, respectively, presented as fold change versus time-matched vehicle-treated cells. OGG1 mRNA expression data was normalized to cyclophilin as an internal control. These data are reported as an average of values obtained from at least 5 different samples ± SEM. (C) Representative western blots for OGG1 protein expression in MCF-10A and T47D cells treated with E2 (50 nM) for 12 and 48 h, respectively. The bar graphs represent fold change in OGG1 protein expression (mean ± SEM), compared to time-matched vehicle-treated cells. ‘*’ indicates p value <0.05 compared to respective age- or time-matched control samples. (D) Representative western blot for OGG1 protein expression in different tissues of female ACI rats treated with E2 for 240 days as described in “Methods” section.