Antioxidants and oxidative stress in patients with Li-Fraumeni-like syndrome and TP53 p.R337H mutation carriers.

e21042 Background: Germline mutations in the TP53 gene are the underlying genetic defect of Li-Fraumeni Syndrome (LFS) and its variant, Li-Fraumeni-like (LFL) Syndrome, autosomal dominant disorders characterized by predisposition to multiple early-onset cancers. More recently, p53 is emerging as an important player in redox metabolism and important enzymes involved in defenses against oxidative stress have shown to be regulated by p53, including glutathione peroxidase 1 (GPX1) and mitochondrial superoxide dismutase 2 (SOD2). The aim of the present study was to investigate the redox profile parameters in blood of p.R337H mutation carriers and non-carriers individuals. Methods: A total of 34 individuals were included in the study and they were divided in two groups: mutation carriers (n=17) and non-carriers (n=17). Antioxidant enzyme activities (SOD, CAT, GPx) and oxidative stress parameters (Protein carbonyl content, Sulfhydryl content and TBARS) were measured in plasma, erythrocytes, leukocytes and serum. Results: Erythrocyte SOD and GPx activities, two first-line players in enzimatic antioxidant defense, differed significantly between mutation carriers and non-carriers, with an increased activity in the latter (p>0,05). Plasma Carbonyl content, an indicative of protein damage related to ROS overgeneration, was also increased in carriers (p=0,015). There was no significant difference between groups in all other parameters evaluated. Conclusions: Our findings suggest that TP53 p.R337H mutation carriers present different antioxidant enzyme activities and oxidative stress parameters when compared to non-carriers.