THE ETIOLOGY OF CANCER - HYDROXYL RADICAL-INDUCED DNA LESIONS IN HISTOLOGICALLY NORMAL LIVERS OF FISH FROM A POPULATION WITH LIVER-TUMORS

Hydroxyl radical-induced DNA lesions were found in hepatic tumors of English sole exposed to environmental chemicals (Malins et al., Carcinogenesis, 11, 1045-1047, 1990; Biochem. Biophys. Res. Commun., 173, 614-619, 1990): they were 8-hydroxyguanine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua), 8-hydroxyadenine and 4,6-diamino-5-formamidopyrimidine (FapyAde). Histologically normal livers from a tumor-bearing population have now been studied. With the exception of FapyAde, the DNA lesion concentrations in the livers were intermediate between those of the initially studied tumor-bearing fish and healthy fish from non-contaminated sites. Thus, the DNA lesions can occur prior to tumor formation, which is consistent with the concept that they are causally linked to tumorigenesis.