PURPOSE: Tumor resistance towards radiation has been a big obstacle in the poor prognosis of lung cancer. It has been reported that hypoxia and autophagy partly contribute to this resistance. However, there is controversy over whether autophagy plays a positive role in cancer therapy or not. We aim to find out the specific mechanism of radiation resistance. MATERIALS AND METHODS: A549 cells were treated with conditioned medium (CM) under 12 h hypoxia or normoxia before irradiation, followed by the measurement of clonogenic survival, reactive oxygen species (ROS), signal of mitochondria and autophagy flux. In some experiments, the A549 cells were respectively transfected with LC3 small interfering RNA (siRNA), or treated with Earle's Balanced Salt Solution (EBSS). RESULTS: We found that hypoxia enhanced cell radioresistance by increasing the induction of autophagy. And after hypoxia stress, the number of mitochondria was reduced but the cellular ROS level was enhanced. It was significant that autophagy may enhance cell radioresistance by reducing ROS during hypoxic treatment. CONCLUSIONS: We elucidated the possible mechanisms of autophagy in regulating cancer cell death or survival. These results supply a new opinion about the intrinsic factor of radioresistance of hypoxia tumors.
PURPOSE: Tumor resistance towards radiation has been a big obstacle in the poor prognosis of lung cancer. It has been reported that hypoxia and autophagy partly contribute to this resistance. However, there is controversy over whether autophagy plays a positive role in cancer therapy or not. We aim to find out the specific mechanism of radiation resistance. MATERIALS AND METHODS: A549 cells were treated with conditioned medium (CM) under 12 h hypoxia or normoxia before irradiation, followed by the measurement of clonogenic survival, reactive oxygen species (ROS), signal of mitochondria and autophagy flux. In some experiments, the A549 cells were respectively transfected with LC3 small interfering RNA (siRNA), or treated with Earle's Balanced Salt Solution (EBSS). RESULTS: We found that hypoxia enhanced cell radioresistance by increasing the induction of autophagy. And after hypoxia stress, the number of mitochondria was reduced but the cellular ROS level was enhanced. It was significant that autophagy may enhance cell radioresistance by reducing ROS during hypoxic treatment. CONCLUSIONS: We elucidated the possible mechanisms of autophagy in regulating cancer cell death or survival. These results supply a new opinion about the intrinsic factor of radioresistance of hypoxia tumors.
Entities:
Keywords:
Hypoxia; ROS; autophagy; lung cancer cells; radioresistance
Authors: Giulia Petroni; Lewis C Cantley; Laura Santambrogio; Silvia C Formenti; Lorenzo Galluzzi Journal: Nat Rev Clin Oncol Date: 2021-11-24 Impact factor: 66.675
Authors: Le Tang; Fang Wei; Yingfen Wu; Yi He; Lei Shi; Fang Xiong; Zhaojian Gong; Can Guo; Xiayu Li; Hao Deng; Ke Cao; Ming Zhou; Bo Xiang; Xiaoling Li; Yong Li; Guiyuan Li; Wei Xiong; Zhaoyang Zeng Journal: J Exp Clin Cancer Res Date: 2018-04-23