Integration of metabolic activation with a predictive toxicogenomics signature to classify genotoxic versus nongenotoxic chemicals in human TK6 cells.
The use of integrated approaches in genetic toxicology, including the incorporation of gene expression data to determine the molecular pathways involved in the response, is becoming more common. In a companion article, a genomic biomarker was developed in human TK6 cells to classify chemicals as genotoxic or nongenotoxic. Because TK6 cells are not metabolically competent, we set out to broaden the utility of the biomarker for use with chemicals requiring metabolic activation. Specifically, chemical exposures were conducted in the presence of rat liver S9. The ability of the biomarker to classify genotoxic (benzo[a]pyrene, BaP; aflatoxin B1, AFB1) and nongenotoxic (dexamethasone, DEX; phenobarbital, PB) agents correctly was evaluated. Cells were exposed to increasing chemical concentrations for 4 hr and collected 0 hr, 4 hr, and 20 hr postexposure. Relative survival, apoptosis, and micronucleus frequency were measured at 24 hr. Transcriptome profiles were measured with Agilent microarrays. Statistical modeling and bioinformatics tools were applied to classify each chemical using the genomic biomarker. BaP and AFB1 were correctly classified as genotoxic at the mid- and high concentrations at all three time points, whereas DEX was correctly classified as nongenotoxic at all concentrations and time points. The high concentration of PB was misclassified at 24 hr, suggesting that cytotoxicity at later time points may cause misclassification. The data suggest that the use of S9 does not impair the ability of the biomarker to classify genotoxicity in TK6 cells. Finally, we demonstrate that the biomarker is also able to accurately classify genotoxicity using a publicly available dataset derived from human HepaRG cells.
Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada.
Julie K
JK
Buick
Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada.|Water and Air Quality Bureau, Health Canada, Ottawa, Ontario, Canada.
Ivy
I
Moffat
Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada.
Andrew
A
Williams
Integrated Laboratory Systems Inc., Research Triangle Park, North Carolina.
Carol D
CD
Swartz
Integrated Laboratory Systems Inc., Research Triangle Park, North Carolina.
Leslie
L
Recio
Biological Engineering Department, Utah State University, Logan, Utah.|Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical Center, Washington, District of Columbia.|Department of Oncology, Georgetown University Medical Center, Washington, District of Columbia.
Daniel R
DR
Hyduke
Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical Center, Washington, District of Columbia.|Department of Oncology, Georgetown University Medical Center, Washington, District of Columbia.
Heng-Hong
HH
Li
Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical Center, Washington, District of Columbia.|Department of Oncology, Georgetown University Medical Center, Washington, District of Columbia.
Albert J
AJ
Fornace
Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut.
Jiri
J
Aubrecht
Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada.
Carole L
CL
Yauk
D065767:Activation, Metabolic; D016604:Aflatoxin B1 / Q000633:toxicity; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001564:Benzo(a)pyrene / Q000633:toxicity; D002460:Cell Line / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000633:toxicity; D003907:Dexamethasone / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D020869:Gene Expression Profiling; D005819:Genetic Markers; D006801:Humans; D015162:Micronucleus Tests; D009153:Mutagens / Q000633:toxicity*; D010634:Phenobarbital / Q000633:toxicity; D051381:Rats; D015203:Reproducibility of Results; D043922:Toxicogenetics / Q000379:methods*
D005819:Genetic Markers; D009153:Mutagens; D001564:Benzo(a)pyrene; D003907:Dexamethasone; D016604:Aflatoxin B1; D002945:Cisplatin; D010634:Phenobarbital
TGx-28.65 classifier; gene expression microarray; genetic toxicology; genomic biomarker; micronucleus