Genome-wide transcriptional responses to acrolein.
The lipid peroxidation product and environmental pollutant acrolein participates in many diseases. Because of its formation during tobacco combustion, its role in various smoking-related respiratory conditions including lung cancer has received increasing attention. As a reactive electrophile, acrolein seems likely to disrupt many biochemical pathways, but these are poorly characterized on a genome-wide basis. This study used microarrays to study short-term transcriptional responses of A549 human lung cells to acrolein, with cells exposed to 100 microM acrolein for 1, 2, or 4 h prior to RNA extraction and transcription profiling. Major pathways dysregulated by acrolein included those involved in apoptosis, cell cycle control, transcription, cell signaling, and protein biosynthesis. Although HMOX1 is a widely used marker of transcriptional responses to acrolein, this gene was the sole upregulated member of the Nrf2-driven family of antioxidant response genes. Transcript levels of several members of the metallothionein class of cytoprotective metal-chelating proteins decreased strongly in response to acrolein. Other novel findings included strong and persistent upregulation of several members of the early growth response (EGR) class of zinc finger transcription factors. Real-time PCR and Western blotting confirmed strong upregulation of a key member of this family (EGR-2), the DNA damage response gene GADD45beta, the heat shock response participant Hsp70, and also HMOX1. Consistent with changes in Nur77 mRNA levels during the microarray study, Western blotting confirmed strong Nur77 induction at the protein level, raising the possibility that this death-inducing protein contributes to the loss of cell viability during acrolein exposure. Collectively, the transcriptional response to acrolein is complex and dynamic, with future work needed to determine whether acrolein-responsive genes identified in this study contribute to cell and tissue injury in the smoke-exposed lung.
Thompson
Colin A
CA
Pharmacology and Anaesthesiology Unit, School of Medicine and Pharmacology, The University of Western Australia, Perth WA 6009, Australia.
Burcham
Philip C
PC
D000171:Acrolein / Q000633:toxicity*; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051767:Early Growth Response Protein 2 / Q000235:genetics / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016678:Genome; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects*; D015854:Up-Regulation; D000097642:GADD45 Proteins
D000171:Acrolein; D000943:Antigens, Differentiation; D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; D004785:Environmental Pollutants; D018840:HSP70 Heat-Shock Proteins; D051547:Heme Oxygenase-1; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D012333:RNA, Messenger; D011987:Receptors, Steroid; C497326:EGR2 protein, human; C086470:GADD45B protein, human; D000097642:GADD45 Proteins; C539821:NR4A1 protein, human; C496541:HMOX1 protein, human