RESUMO
PURPOSE: We investigated the impact of anthracycline-based chemotherapy on methylation status of RB1 gene in peripheral blood leukocytes together with parameters of oxidative stress and inflammation in sarcoma patients. PATIENTS/METHODS: Blood samples were collected from 51 consecutive newly diagnosed sarcoma patients admitted to University Hospital Center Zagreb (Zagreb, Croatia) for first-line chemotherapy before the first cycle and post-chemotherapy. Methylation and copy number variation (CNV) of leukocyte RB1 gene were assessed using MS-MLPA probes. In addition, in blood samples, parameters of oxidative stress (ROS, MDA, SOD, and GSH) and inflammation (CRP, WBC, and NBC) were followed. RESULTS: In pre-chemotherapy samples, no CNVs and aberrant methylation of CpG106 promoter region of RB1 gene were detected; however, one patient had hypermethylation (by approximately 10%) of imprinted locus CpG85 in intron 2 of RB1 gene. In addition, a very good correlation of the tumor burden and CRP and tumor burden and GSH was found. The anthracycline-based chemotherapy reverts methylation of RB1 gene-imprinted locus CpG85 to normal level. Moreover, inflammation and oxidative stress parameters such as CRP, WBC, ROS, and MDA were significantly decreased in post-chemotherapy samples. CONCLUSION: This single-centered study on a cohort of consecutive sarcoma patients indicates that sarcoma patients can have aberrant germline DNA methylation and confirms the relationship of tumor burden with inflammation and oxidative stress. The applied chemotherapy protocols reverted RB1 gene methylation to normal level and decreased the level of inflammation and oxidative damage, thus indicating chemotherapy benefit to the patient's health status.
