As. Wilson et al., BIOACTIVATION AND INACTIVATION OF AFLATOXIN B-1 BY HUMAN, MOUSE AND RAT-LIVER PREPARATIONS - EFFECT ON SCE IN HUMAN MONONUCLEAR LEUKOCYTES, Mutation research, 373(2), 1997, pp. 257-264
The purpose of this study was to investigate the use of human and anim
al subcellular liver fractions in an in vitro evaluation of carcinogen
ic risk. The bioactivation and bioinactivation of the known genotoxic
carcinogen aflatoxin B-1 by human, mouse and rat liver preparations wa
s investigated using the SCE assay in human lymphocytes as a genotoxic
endpoint. There was a 10-fold variation in SCE response (1.1-11.6 SCE
/Cell) in human mononuclear leucocytes (MNLs) after aflatoxin B-1 was
activated by human liver microsomes (n=6). Activation correlated with
the CYP1A2 phenotype of livers (r=0.8; p<0.05), but there was no corre
lation with either GST M1 genotype or epoxide hydrolase phenotype. Mou
se liver microsomes activated aflatoxin B-1 to a greater extent [(1 mu
M) 12.8+/-2.51 SCE/Cell] than either rat [(10 mu M) 12.0+/-3.84 SCE/C
ell] or human (L25) [(10 mu M) 8.8+/-2.00 SCE/Cell] liver microsomes.
The addition of mouse liver cytosol and reduced glutathione (GSH) sign
ificantly (p<0.001) reduced aflatoxin B-1-dependent genotoxicity, wher
eas the addition of either human or rat cytosol (+GSH) was without eff
ect. These data indicate that species variation in both bioactivation
and bioinactivation can exist. Therefore there is a necessity for care
ful selection of activation systems from species whose biochemical pro
file reflects that of man.