title: ATM pathway is essential for ionizing radiation-induced autophagy.
abstract: BACKGROUND
  ATM plays an important role in response to DNA damage, while the roles of ATM in radiation-induced autophagy are still unclear in cervical cancer cells.
  
  
  METHODS
  Human cervical cancer cells, Hela, were used, and cell models with ATM(-/-) and MAPK14(-/-) were established by gene engineering. Western blot was implemented to detect protein expression. MDC staining and GFP-LC3 relocalization were used to detect autophagy. CCK-8 was used to detect cell viability. Radiosensitivity was analyzed by colony formation assays. Co-immunoprecipitation was used to detect the interaction between different proteins, and apoptosis was detected by flow cytometry.
  
  
  RESULTS
  After radiation autophagy was induced, illustrated by the increase of MAPLC3-II/MAPLC3-I ratio and decrease of p62, and phosphorylation of ATM simultaneously increased. ATM(-/-) cells displayed hypersensitivity but had no influence on IR-induced apoptosis. Then inhibitor of ATM, KU55933, ATM and MAPK14 silencing were used, and autophagy was induced by IR more than 200% in control, and only by 35.72%, 53.18% and 24.76% in KU55933-treated cells, ATM(-/-) and MAPK14(-/-) cells, respectively. KU55933 inhibited IR-induced autophagy by activating mTOR pathways. ATM silencing decreased the expression of MAPK14 and mTOR signals significantly. Beclin's bond to PI3KIII and their interaction increased after IR, while in ATM(-/-) and MAPK14(-/-) cells this interaction decreased after IR. Both ATM and MAPK14 interacted with Beclin, while ATM(-/-) and MAPK14(-/-) cells showed no interaction.
  
  
  CONCLUSIONS
  ATM could promote IR-induced autophagy via the MAPK14 pathway, the mTOR pathway, and Beclin/PI3KIII complexes, which contributed to the effect of ATM on radiosensitivity.
authors.affiliation: Key Laboratory of Radiobiology (Ministry of Health), School of Public Health, Jilin University, Changchun 130021, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Liang
authors.forename: Lili
authors.initials: L
authors.lastname: Jia
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Bing
authors.initials: B
authors.lastname: Liang
authors.forename: Dejuan
authors.initials: D
authors.lastname: Kong
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Yan
authors.forename: Shumei
authors.initials: S
authors.lastname: Ma
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Liu
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000528:radiation effects*; D058546:Class III Phosphatidylinositol 3-Kinases / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D048308:Mitogen-Activated Protein Kinase 14 / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011839:Radiation, Ionizing; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; D058546:Class III Phosphatidylinositol 3-Kinases; D064007:Ataxia Telangiectasia Mutated Proteins; D058570:TOR Serine-Threonine Kinases; D048308:Mitogen-Activated Protein Kinase 14
keywords: ATM; Autophagy; Ionizing radiation