The Role Of Atm In The Low-dose Hyperradiosensitivity And Increased Radioresistance (HRS/IRR) Response Of Lung Cancer Via Autophagy Regulation

Objective: Radiation therapy is an important means of tumor therapy,but due to the radiation resistance and damage to the surrounding normal tissues during the course of radiotherapy,its clinical application is limited.This study intends to explore the effects of ATM and autophagy on the radiation sensitivity of lung cancer under low dose radiation,and further study their role in the transition from HRS to IRR and the mechanism of their interaction.Methods: In this study,human lung cancer cell lines A549 and H460 were taken as the research objects.The clone formation experiment was used to verify the existence of HRS in A549 and H460 cells.Western Blot was used to detect the difference in the expression of ATM in A549 and H460 cell lines.Western Blot,immunofluorescence and electron microscopy verified the changes of A549 and H460 ATM protein expression levels and cell autophagy levels under different low-dose radiation.The expression of ATM was knocked down by si RNA transfection,and the changes of cell radiosensitivity and cell autophagy level were observed.Transcriptomics sequencing analysis screened out the molecules related to the autophagy pathway downstream of ATM,verified the sequencing results by PCR,and verified their effect on radiosensitivity and phagocytosis of A549 cells under low-dose radiation by si RA transfection,clone formation and Western Blot.The nude mouse xenograft model verified the results of the cell experiment.Results:(1)A549 cells with high expression of ATM showed HRS / IRR positive,and H460 with low expression of ATM showed HRS / IRR negative.(2)The phenomenon of A549 cells increased after si RNA silenced ATM expression,and the radiotherapy sensitivity of H460 cells also increased.(3)Silencing ATM expression by si RNA inhibited the increase of autophagy in A549 cells and H460 cells after different low doses of radiation,and also suppressed the increase of autophagy-related genes p-JNK and AMBRA1.(4)After silencing the expression of JNK and AMBRA1 by si RNA,the HRS phenomenon of A549 cells increased,and at the same time,the autophagy level of A549 cells under low dose radiation was also suppressed.Conclusion:(1)The transition from HRS to IRR is related to the high expression of ATM.Inhibiting ATM expression can increase the sensitivity of cells to low-dose radiation.(2)Inhibiting ATM expression can down-regulate the autophagy level of cells under different low-dose radiation.(3)ATM may regulate autophagy through p-JNK and AMBRA1 signaling pathways and then participate in the regulation of HRS / IRR phenomenon.