title: Mutational spectra of aflatoxin B1in vivo establish biomarkers of exposure for human hepatocellular carcinoma.
abstract: Aflatoxin B1(AFB1) and/or hepatitis B and C viruses are risk factors for human hepatocellular carcinoma (HCC). Available evidence supports the interpretation that formation of AFB1-DNA adducts in hepatocytes seeds a population of mutations, mainly G:C→T:A, and viral processes synergize to accelerate tumorigenesis, perhaps via inflammation. Responding to a need for early-onset evidence predicting disease development, highly accurate duplex sequencing was used to monitor acquisition of high-resolution mutational spectra (HRMS) during the process of hepatocarcinogenesis. Four-day-old male mice were treated with AFB1using a regimen that induced HCC within 72 wk. For analysis, livers were separated into tumor and adjacent cellular fractions. HRMS of cells surrounding the tumors revealed predominantly G:C→T:A mutations characteristic of AFB1exposure. Importantly, 25% of all mutations were G→T in one trinucleotide context (CGC; the underlined G is the position of the mutation), which is also a hotspot mutation in human liver tumors whose incidence correlates with AFB1exposure. The technology proved sufficiently sensitive that the same distinctive spectrum was detected as early as 10 wk after dosing, well before evidence of neoplasia. Additionally, analysis of tumor tissue revealed a more complex pattern than observed in surrounding hepatocytes; tumor HRMS were a composite of the 10-wk spectrum and a more heterogeneous set of mutations that emerged during tumor outgrowth. We propose that the 10-wk HRMS reflects a short-term mutational response to AFB1, and, as such, is an early detection metric for AFB1-induced liver cancer in this mouse model that will be a useful tool to reconstruct the molecular etiology of human hepatocarcinogenesis.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Supawadee
authors.initials: S
authors.lastname: Chawanthayatham
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Charles C
authors.initials: CC
authors.lastname: Valentine
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Bogdan I
authors.initials: BI
authors.lastname: Fedeles
authors.affiliation: Department of Pathology, University of Washington, Seattle, WA 98195.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Fox
authors.affiliation: Department of Pathology, University of Washington, Seattle, WA 98195.|Department of Biochemistry, University of Washington, Seattle, WA 98195.
authors.forename: Lawrence A
authors.initials: LA
authors.lastname: Loeb
authors.affiliation: Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Stuart S
authors.initials: SS
authors.lastname: Levine
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Slocum
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139; jessig@mit.edu wogan@mit.edu.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Gerald N
authors.initials: GN
authors.lastname: Wogan
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Croy
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139; jessig@mit.edu wogan@mit.edu.|Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.|Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: John M
authors.initials: JM
authors.lastname: Essigmann
mesh_terms: D016604:Aflatoxin B1 / Q000235:genetics* / Q000633:toxicity; D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D063646:Carcinogenesis / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018736:DNA Adducts / Q000235:genetics* / Q000633:toxicity; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009154:Mutation
chemical_list: D015415:Biomarkers; D018736:DNA Adducts; C072611:aflatoxin B1-DNA adduct; D016604:Aflatoxin B1
keywords: cancer; duplex sequencing; mouse model; mutagenesis; mycotoxins