Significance of apoptosis and autophagy of leukemic blasts for the outcomes of acute myeloid leukemia patients

Abstract

Background. Cytostatic treatment induces apoptosis or other types of cell death like autophagy, necrosis, mitotic catastrophe, etc. Autophagy can play a role in the drug resistance of neoplastic cells, allowing the survival of blast cells under stressful conditions, such as the use of cytostatics. Studies on apoptosis and autophagy 12-24 h after the start of treatment have not been conducted until now. Objectives. The study aimed to investigate the predictive and prognostic significance of autophagy and apoptosis in patients with acute myeloid leukemia (AML). Material and methods. The study included 38 patients. Blood was collected before and 12-24 h after the start of treatment, since at that time point, the appropriate blast cell count was still available. Autophagy was measured with the expression of the ATG5, MAP1L3, LC3-I, and LC3-II proteins. The percentage of mononuclear cells in early and late apoptosis was evaluated with flow cytometry, using the annexin V and propidium iodide (PI) binding assay. Results. The percentage of apoptotic blast cells before treatment was not associated with the response. However, in the remission group, the overall percentage of apoptotic cells measured 12-24 h after the start of treatment was higher than in non-remission patients, which was statistically significant. In neither group we found any difference in the level of autophagy before and 12-24 h after the start of treatment. Nevertheless, we observed an increasing tendency of the MAP1LC3 protein expression (not statistically significant) in the remission group 12-24 h after the start of treatment. Patients with a higher percentage of blast cells in apoptosis and with a higher expression of MAP1LC3 protein measured 12-24 h after the start of the therapy had longer overall survival (OS). Conclusions. A higher percentage of apoptotic as well as autophagic blast cells measured 12-24 h after the start of the chemotherapy is an independent factor associated with better outcomes.