Toxicity of 6-thioguanine and 8-azaguanine to non-dividing liver cell cultures.

8-azaguanine and 6-thioguanine were both toxic to non-dividing liver cells in primary cultures. In addition, these agents were toxic to an established line of liver-derived epithelial cells brought to growth arrest by serum deprivation. These observations demonstrate that the toxicity of 8-azaguanine and 6-thioguanine can occur at least in part through mechanisms that do not involve effects on DNA synthesis or incorporation of the analogs into DNA.