title: Transcriptional and physiological responses of HepG2 cells exposed to diethyl maleate: time course analysis.
abstract: Expression levels of 767 genes were measured in HepG2 cells at eight time points (0, 0.5, 1, 6, 12, 16, 20, and 24 h) following exposure to the oxidizing agent, diethyl maleate (DEM). DEM treatment caused an immediate and sustained loss of intracellular GSH, with a concomitant increase in GSSG. From 6-12 h after exposure, there was a substantial increase in the percentage of cells undergoing S phase arrest and apoptosis. Expression profiles of approximately 90% of the genes fell into one of five clusters generated using hierarchical-clustering software, indicating the well-ordered nature of the stress response. The directional movement and timing of induction for many genes matched closely the known physiological role of the proteins they encode. Inhibitors of the cell cycle (CDKN1, CDKN4D, ATM) were induced, whereas cyclins [proliferating cell nuclear antigen (PCNA), cyclin A, cyclin D1, cyclin K] were downregulated during the period from 6--20 h. Likewise, pro-apoptotic genes such as the caspases (CASP9, CASP3, CASP2) and apoptotic protease activating factor (APAF) were induced during the same period. Results of this study indicate that there is a good correlation between time-dependent physiological, biochemical, and gene expression data.
authors.affiliation: Toxicogenomics, GlaxoSmithKline, Research Triangle Park, North Carolina 27709, USA. wmc22442@gsk.com
authors.forename: Warren
authors.initials: W
authors.lastname: Casey
authors.forename: Steve
authors.initials: S
authors.lastname: Anderson
authors.forename: Tony
authors.initials: T
authors.lastname: Fox
authors.forename: Karen
authors.initials: K
authors.lastname: Dold
authors.forename: Heidi
authors.initials: H
authors.lastname: Colton
authors.forename: Kevin
authors.initials: K
authors.lastname: Morgan
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015139:Blotting, Southern / Q000379:methods; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology*; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology*; D008298:Maleates / Q000494:pharmacology*; D016011:Normal Distribution; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012334:RNA, Neoplasm / Q000187:drug effects; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects* / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D008298:Maleates; D016877:Oxidants; D012334:RNA, Neoplasm; C014476:diethyl maleate