The aflatoxin B1 formamidopyrimidine adduct plays a major role in causing the types of mutations observed in human hepatocellular carcinoma

Maryann E. Smela, Michelle L. Hamm, Paul Henderson, Constance M. Harris, Thomas M. Harris, John M. Essigmann

Research output: Contribution to journalArticle

136 Citations (Scopus)

Abstract

A G to T mutation has been observed at the third position of codon 249 of the p53 tumor-suppressor gene in over 50% of the hepatocellular carcinoma cases associated with high exposure to aflatoxin B1 (AFB1). Hypotheses have been put forth that AFB1, in concert with hepatitis B virus (HBV), may play a role in the formation of, and/or the selection for, this mutation. The primary DNA adduct of AFB1 is 8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B1 (AFB1-N7-Gua), which is converted naturally to two secondary lesions, an apurinic site and an AFB1-formamidopyrimidine (AFB1-FAPY) adduct. AFB1-FAPY is detected at near maximal levels in rat DNA days to weeks after AFB1 exposure, underscoring its high persistence in vivo. The present study reveals two striking properties of this DNA adduct: (i) AFB1-FAPY was found to cause a G to T mutation frequency in Escherichia coli approximately 6 times higher than that of AFB1-N7-Gua, and (ii) one proposed rotamer of AFB1-FAPY is a block to replication, even when the efficient bypass polymerase MucAB is used by the cell. Taken together, these characteristics make the FAPY adduct the prime candidate for both the genotoxicity of aflatoxin, because mammalian cells also have similar bypass mechanisms for combating DNA damage, and the mutagenicity that ultimately may lead to liver cancer.

Original languageEnglish (US)
Pages (from-to)6655-6660
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number10
DOIs
StatePublished - May 14 2002
Externally publishedYes

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Aflatoxin B1
Hepatocellular Carcinoma
Mutation
Aflatoxins
Mutation Rate
Liver Neoplasms
aflatoxin B1-formamidopyrimidine
Tumor Suppressor Genes
Hepatitis B virus
Codon
DNA Damage
Escherichia coli
DNA

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

The aflatoxin B1 formamidopyrimidine adduct plays a major role in causing the types of mutations observed in human hepatocellular carcinoma. / Smela, Maryann E.; Hamm, Michelle L.; Henderson, Paul; Harris, Constance M.; Harris, Thomas M.; Essigmann, John M.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 99, No. 10, 14.05.2002, p. 6655-6660.

Research output: Contribution to journalArticle

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