Starvation of leukemic cells enhances DNA damage-induced apoptosis in vitro via ROS/p38 MAPK and prevents leukemia progression in fasting xenograft mice

Most children with acute lymphoblastic leukemia (ALL) achieve long-term survival due to intensive multimodal chemotherapy. However, the use of cytotoxic DNA-damaging agents is frequently associated with severe long-term side effects, prompting continued efforts to improve treatment strategies. This study explores the potential of starving the leukemic cells to enhance the efficacy of DNA-damaging therapy in ALL. Previous work demonstrated that cAMP signaling attenuates DNA damage-induced apoptosis in ALL cells, both in vitro and in a xenograft model. The current findings show that glucose and serum deprivation reverse the effect of cAMP, converting it from a survival factor to a promoter of DNA damage-induced apoptosis in ALL-derived cell lines and patient-derived leukemic cells in vitro. The starvation-induced sensitization was independent of p53 but was shown to require increased levels of reactive oxygen species (ROS). In turn, the elevated ROS levels enhanced the activation of the mitogen-activated protein kinase p38 (p38 MAPK). The resulting augmented cell death was inhibited both by the ROS scavenger N-acetyl cysteine and the p38 MAPK inhibitor SB 202190. The translational potential of increasing the efficacy of DNA damaging agents in starving ALL cells was supported by in vivo data showing that intermittent fasting, combined with subtherapeutic doses of irradiation, significantly inhibits the leukemia progression in a xenograft model of severe combined immunodeficiency mice.