In vitro recapitulating of TP53 mutagenesis in hepatocellular carcinoma associated with dietary aflatoxin B1 exposure

Gastroenterology. 2009 Sep;137(3):1127-37, 1137.e1-5. doi: 10.1053/j.gastro.2009.06.002. Epub 2009 Jun 12.


Background & aims: Dietary exposure to aflatoxin B(1) (AFB(1)), in addition to other known factors, increases risk for human hepatocellular carcinoma (HCC). HCCs from AFB(1)-exposed individuals frequently have distinct TP53 mutations, such as G to T transversions in the second guanine of codon 249 (AGG to AGT), and a characteristic mutational spectrum predominated by G:C to T:A mutations.

Methods: To recapitulate the distinctive features of TP53 mutations in AFB(1)-associated HCC, we investigated AFB(1)-induced DNA adduction in relation to mutagenesis in transgenic mouse fibroblasts exposed to AFB(1) in vitro.

Results: Immunodotblot determination of DNA adducts in the overall genome of AFB(1)-exposed cells revealed the dose-dependant formation of persistent imidazole ring-opened AFB(1)-DNA adducts. DNA footprinting analysis of the cII transgene in AFB(1)-exposed cells verified the dose-dependent and sequence-specific formation of DNA adducts. The preferential formation of AFB(1)-induced DNA adducts along the cII transgene was almost exclusively localized to guanine-containing sequences encompassing CpG dinucleotides. Mutation analysis of the cII transgene in AFB(1)-exposed cells revealed a dose-dependent induction of cII mutant frequency (P < .001) and a unique induced mutational spectrum characterized by predominant induction of G:C to T:A transversions that occurred within CpG sequence contexts. Notably, codons 42 and 45 of the cII transgene, which have identical sequence contexts to that of codon 249 of human TP53, constituted 2 frequently mutated sites in AFB(1)-exposed cells that contained the G to T transversion signature mutation at their third base positions.

Conclusions: In this model system, AFB(1)-induced DNA adduction and mutagenesis recapitulate the unique mutational features of TP53 in AFB(1)-associated human HCC.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aflatoxin B1 / toxicity*
  • Animals
  • Carcinogens / toxicity*
  • Carcinoma, Hepatocellular / chemically induced
  • Carcinoma, Hepatocellular / genetics*
  • Cells, Cultured
  • DNA Adducts / metabolism
  • DNA Damage / drug effects
  • Dose-Response Relationship, Drug
  • Fibroblasts / drug effects
  • Genes, p53 / genetics*
  • Liver Neoplasms / chemically induced
  • Liver Neoplasms / genetics*
  • Mice
  • Mice, Transgenic
  • Mutagenicity Tests
  • Mutation / drug effects*


  • Carcinogens
  • DNA Adducts
  • Aflatoxin B1