RESUMO
PURPOSE: Although the etiology of breast cancer is multifactorial, oxidative stress plays an important role in carcinogenesis. In this study, manganese superoxide dismutase (MnSOD) gene polymorphism and activity were evaluated in benign and breast cancer tissue. METHODS: One hundred and one females were enrolled in this study, 65 who were histopathologically diagnosed with breast cancer and 46 who were benign patients. MnSOD enzyme activity was determined using an indirect competitive inhibition assay and MnSOD gene polymorphism using poly merase chain reaction and agarose gel electrophoresis. RESULTS: MnSOD enzymatic activity (79.83+/-42.14) was lower in breast cancer tissue compared to benign tumors (236.18+/-46.37). At the same time, MnSOD enzymatic activity among Ala/Val patients was significantly lower in breast cancer tissue (39.19+/-7.33) than in Val/Val malignant breast tumors tissue (96.9+/-22.9). MnSOD enzymatic activity was significantly lower in Val/Val cancer tissue (96.9+/-22.9) than in benign tissue (255.44+/-42.7). CONCLUSION: Breast cancer tumors contain less MnSOD than benign breast samples. Patients with Ala/Val polymorphism had reduced MnSOD activity compared to patients with Val/Val breast cancer. Ala/Val gene polymorphism may be a risk factor associated with more advanced breast cancer stage. MnSOD gene polymorphism Ala/Val may be a risk factor associated with more advanced breast cancer stage, and reduction of MnSOD activity may be a mechanism of the progression of benign to malignant tumors. Further investigations are needed to evaluate the role of MnSOD in breast cancer progression.