title: Global gene expression profiling in human lung cells exposed to cobalt.
abstract: BACKGROUND
  It has been estimated that more than 1 million workers in the United States are exposed to cobalt. Occupational exposure to 59 Co occurs mainly via inhalation and leads to various lung diseases. Cobalt is classified by the IARC as a possible human carcinogen (group 2B). Although there is evidence for in vivo and in vitro toxicity, the mechanisms of cobalt-induced lung toxicity are not fully known. The purpose of this work was to identify potential signatures of acute cobalt exposure using a toxicogenomic approach. Data analysis focused on some cellular processes and protein targets that are thought to be relevant for carcinogenesis, transport and biomarker research.
  
  
  RESULTS
  A time course transcriptome analysis was performed on A549 human pulmonary cells, leading to the identification of 85 genes which are repressed or induced in response to soluble 59 Co. A group of 29 of these genes, representing the main biological functions, was assessed by quantitative RT-PCR. The expression profiles of six of them were then tested by quantitative RT-PCR in a time-dependent manner and three modulations were confirmed by Western blotting. The 85 modulated genes include potential cobalt carriers (FBXL2, ZNT1, SLC12A5), tumor suppressors or transcription factors (MAZ, DLG1, MYC, AXL) and genes linked to the stress response (UBC, HSPCB, BNIP3L). We also identified nine genes coding for secreted proteins as candidates for biomarker research. Of those, TIMP2 was found to be down-regulated and this modulation was confirmed, in a dose-dependent manner, at protein level in the supernatant of exposed cells.
  
  
  CONCLUSIONS
  Most of these genes have never been described as related to cobalt stress and provide original hypotheses for further study of the effects of this metal ion on human lung epithelial cells. A putative biomarker of cobalt toxicity was identified.
authors.affiliation: Service de Biochimie et Toxicologie Nucléaire, DSV/iBEB, CEA VALRHO, Bagnols-sur-Cèze, France. veronique.malard@cea.fr
authors.forename: Veronique
authors.initials: V
authors.lastname: Malard
authors.forename: Frederic
authors.initials: F
authors.lastname: Berenguer
authors.forename: Odette
authors.initials: O
authors.lastname: Prat
authors.forename: Sylvie
authors.initials: S
authors.lastname: Ruat
authors.forename: Gerard
authors.initials: G
authors.lastname: Steinmetz
authors.forename: Eric
authors.initials: E
authors.lastname: Quemeneur
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D003035:Cobalt / Q000633:toxicity*; D017931:DNA Primers / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D005819:Genetic Markers / Q000235:genetics; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D016273:Occupational Exposure; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics
chemical_list: D017931:DNA Primers; D005819:Genetic Markers; D051793:Hypoxia-Inducible Factor 1; D014157:Transcription Factors; D019716:Tissue Inhibitor of Metalloproteinase-2; D003035:Cobalt; D000255:Adenosine Triphosphate