title: Membrane-derived second messenger regulates x-ray-mediated tumor necrosis factor alpha gene induction.
abstract: Cells adapt to adverse environmental conditions through a wide range of responses that are conserved throughout evolution. Physical agents such as ionizing radiation are known to initiate a stress response that is triggered by the recognition of DNA damage. We have identified a signaling pathway involving the activation of phospholipase A2 and protein kinase C in human cells that confers x-ray induction of the tumor necrosis factor alpha gene. Treatment of human cells with ionizing radiation or H2O2 was associated with the production of arachidonic acid. Inhibition of phospholipase A2 abolished radiation-mediated arachidonate production as well as the subsequent activation of protein kinase C and tumor necrosis factor alpha gene expression. These findings demonstrate that ionizing radiation-mediated gene expression in human cells is regulated in part by extranuclear signal transduction. One practical application of phospholipase A2 inhibitors is to ameliorate the adverse effects of radiotherapy associated with tumor necrosis factor alpha production.
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago, IL 60637.
authors.forename: D E
authors.initials: DE
authors.lastname: Hallahan
authors.forename: S
authors.initials: S
authors.lastname: Virudachalam
authors.forename: J
authors.initials: J
authors.lastname: Kuchibhotla
authors.forename: D W
authors.initials: DW
authors.lastname: Kufe
authors.forename: R R
authors.initials: RR
authors.lastname: Weichselbaum
mesh_terms: D000595:Amino Acid Sequence; D001095:Arachidonic Acids / Q000096:biosynthesis; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000528:radiation effects*; D006801:Humans; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000378:metabolism; D015290:Second Messenger Systems; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D001095:Arachidonic Acids; D014409:Tumor Necrosis Factor-alpha; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2