title: PI3Kγ activation is required for LPS-induced reactive oxygen species generation in respiratory epithelial cells.
abstract: OBJECTIVE
  In this study, we investigated the molecular basis of reactive oxygen species (ROS) generation induced by lipopolysaccharide (LPS) in A549 cells--an alveolar epithelial cell line.
  
  
  METHODS
  A549 cells or normal human bronchial epithelial (NHBE) cells were stimulated with LPS. ROS generation was measured in A549 cells or NHBE cells pre-treated with a selective inhibitor of phosphatidylinositol 3-kinase γ (PI3Kγ), AS 605240, PI3Kγ siRNA, or a ROS scavenger, pyridoxamine (PM).
  
  
  RESULTS
  Treatment of A549 cells or NHBE cells with LPS caused a significant increase in intracellular ROS generation. Pretreatment with the PI3Kγ inhibitor, AS 605240 decreased the LPS-induced increase of ROS generation, phosphorylation of Akt, and production of phosphatidyl 3,4,5-trisphosphate in A549 cells. In addition, interference with siRNA for PI3Kγ significantly reduced LPS-induced ROS generation in A549 cells. Treatment of A549 cells with LPS or hydrogen peroxide increased the nuclear factor-κB (NF-κB) in the nucleus, accompanying an increase in phosphorylation of inhibitory κB-α, degradation of the protein, and reduction of cytosolic NF-κB. Pretreatment with AS 605240 reduced these LPS-induced changes. In addition, pretreatment with PM or N-acetyl cysteine resulted in inhibition of nuclear NF-κB activation.
  
  
  CONCLUSIONS
  These results suggest that PI3Kγ plays a key role in LPS-induced ROS generation in alveolar epithelial cells, thereby activating NF-κB.
authors: Department of Internal Medicine, Research Center for Pulmonary Disorders, Chonbuk National University Medical School, San 2-20 Geumam-dong, Deokjin-gu, Jeonbuk, Jeonju 561-180, South Korea.
authors: Hee Jung
authors: HJ
authors: Kim
authors: So Ri
authors: SR
authors: Kim
authors: Jin Kyeong
authors: JK
authors: Park
authors: Dong Im
authors: DI
authors: Kim
authors: Jae Seok
authors: JS
authors: Jeong
authors: Yong Chul
authors: YC
authors: Lee
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D058544:Class Ib Phosphatidylinositol 3-Kinase / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008070:Lipopolysaccharides; D008168:Lung / Q000166:cytology; D016328:NF-kappa B / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011810:Quinoxalines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D045162:Thiazolidinediones / Q000494:pharmacology
chemical_list: C505144:5-quinoxalin-6-ylmethylenethiazolidine-2,4-dione; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011810:Quinoxalines; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D045162:Thiazolidinediones; D006861:Hydrogen Peroxide; D058544:Class Ib Phosphatidylinositol 3-Kinase; C546760:PIK3CG protein, human