Benzo[a]pyrene-induced transcriptomic responses in primary hepatocytes and in vivo liver: toxicokinetics is essential for in vivo-in vitro comparisons.
The traditional 2-year cancer bioassay needs replacement by more cost-effective and predictive tests. The use of toxicogenomics in an in vitro system may provide a more high-throughput method to investigate early alterations induced by carcinogens. Recently, the differential gene expression response in wild-type and cancer-prone Xpa                 (-/-)                 p53                 (+/-) primary mouse hepatocytes after exposure to benzo[a]pyrene (B[a]P) revealed downregulation of cancer-related pathways in Xpa                 (-/-)                 p53                 (+/-) hepatocytes only. Here, we investigated pathway regulation upon in vivo B[a]P exposure of wild-type and Xpa                 (-/-)                 p53                 (+/-) mice. In vivo transcriptomics analysis revealed a limited gene expression response in mouse livers, but with a significant induction of DNA replication and apoptotic/anti-apoptotic cellular responses in Xpa                 (-/-)                 p53                 (+/-) livers only. In order to be able to make a meaningful in vivo-in vitro comparison we estimated internal in vivo B[a]P concentrations using DNA adduct levels and physiologically based kinetic modeling. Based on these results, the in vitro concentration that corresponded best with the internal in vivo dose was chosen. Comparison of in vivo and in vitro data demonstrated similarities in transcriptomics response: xenobiotic metabolism, lipid metabolism and oxidative stress. However, we were unable to detect cancer-related pathways in either wild-type or Xpa                 (-/-)                 p53                 (+/-) exposed livers, which were previously found to be induced by B[a]P in Xpa                 (-/-)                 p53                 (+/-) primary hepatocytes. In conclusion, we showed parallels in gene expression responses between livers and primary hepatocytes upon exposure to equivalent concentrations of B[a]P. Furthermore, we recommend considering toxicokinetics when modeling a complex in vivo endpoint with in vitro models.
Laboratory for Health Protection Research, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA, Bilthoven, The Netherlands.
P C E
PC
van Kesteren
P E
PE
Zwart
M M
MM
Schaap
T E
TE
Pronk
M H M
MH
van Herwijnen
J C S
JC
Kleinjans
B G H
BG
Bokkers
R W L
RW
Godschalk
M J
MJ
Zeilmaker
H
H
van Steeg
M
M
Luijten
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001564:Benzo(a)pyrene / Q000493:pharmacokinetics / Q000633:toxicity*; D015197:Carcinogenicity Tests / Q000379:methods*; D002273:Carcinogens / Q000493:pharmacokinetics / Q000633:toxicity*; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D003198:Computer Simulation; D018736:DNA Adducts / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D057166:High-Throughput Screening Assays; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D061251:Primary Cell Culture; D018570:Risk Assessment; D014158:Transcription, Genetic / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D051760:Xeroderma Pigmentosum Group A Protein / Q000235:genetics
D002273:Carcinogens; D018736:DNA Adducts; D016159:Tumor Suppressor Protein p53; D051760:Xeroderma Pigmentosum Group A Protein; C497315:Xpa protein, mouse; D001564:Benzo(a)pyrene