Aflatoxin B(1): Cytotoxic mode of action evaluated by mammalian cell cultures.

Aflaxton B(1) rapidly inhibits RNA synthesis in rat liver cells, slices or liver in vivo. Established human cells lines (kidney T-cells, HeLa S(3), Chang liver) and mouse fibroblast 3t3 are more slowly affected. Prolonged exposure of synchronized cell cultures to the agent show that cells are retarded in their passage through the S-phase and exhibit a decreased rate of DNA synthesis. Consequent to this, mitosis is also inhibited. Liver cells appear to convert aflatoxin B(1) to a more potent cytotoxin which can then affect normally non-susceptible cells. This may explain the susceptibility of liver to tumorogenesis by this carcinogen.