Levels of 4-aminobiphenyl-induced somatic H-ras mutation in mouse liver DNA correlate with potential for liver tumor development.
The utility of liver H-ras codon 61 CAA to AAA mutant fraction as a biomarker of liver tumor development was investigated using neonatal male mice treated with 4-aminobiphenyl (4-ABP). Treatment with 0.1, 0.3, or 1.0 mumol 4-ABP produced dose-dependent increases in liver DNA adducts in B6C3F(1) and C57BL/6N mice. Eight months after treatment with 0.3 mumol 4-ABP or the DMSO vehicle, H-ras codon 61 CAA to AAA mutant fraction was measured in liver DNA samples (n = 12) by allele-specific competitive blocker-polymerase chain reaction (ACB-PCR). A significant increase in average mutant fraction was found in DNA of 4-ABP-treated mice, with an increase from 1.3 x 10(-5) (control) to 44.9 x 10(-5) (treated) in B6C3F(1) mice and from 1.4 x 10(-5) to 7.0 x 10(-5) in C57BL/6N mice. Compared with C57BL/6N mutant fractions, B6C3F(1) mutant fractions were more variable and included some particularly high mutant fractions, consistent with the more rapid development of liver foci expected in B6C3F(1) mouse liver. Twelve months after treatment, liver tumors developed in 79.2% of 4-ABP-treated and 22.2% of control B6C3F(1) mice; thus measurement of H-ras mutant fraction correlated with subsequent tumor development. This study demonstrates that ACB-PCR can directly measure background levels of somatic oncogene mutation and detect a carcinogen-induced increase in such mutation.
Parsons
Barbara L
BL
Division of Genetic and Reproductive Toxicology, US FDA National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA.
Beland
Frederick A
FA
Von Tungeln
Linda S
LS
Delongchamp
Robert R
RR
Fu
Peter P
PP
Heflich
Robert H
RH
D000611:Aminobiphenyl Compounds / Q000633:toxicity*; D000818:Animals; D000831:Animals, Newborn; D002273:Carcinogens / Q000633:toxicity*; D003062:Codon / Q000235:genetics; D003433:Crosses, Genetic; D004247:DNA / Q000187:drug effects / Q000235:genetics*; D004121:Dimethyl Sulfoxide; D005260:Female; D011905:Genes, ras / Q000187:drug effects / Q000235:genetics*; D008099:Liver / Q000187:drug effects / Q000502:physiology*; D008113:Liver Neoplasms / Q000139:chemically induced / Q000235:genetics*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D013045:Species Specificity
D000611:Aminobiphenyl Compounds; D002273:Carcinogens; D003062:Codon; C006757:4-biphenylamine; D004247:DNA; D004121:Dimethyl Sulfoxide