Bile acids do not form adducts when incubated with DNA in vitro

Bile acids have been implicated in the aetiology of colon cancer. We have previously found, using 32P-postlabelling, that bile from control patients and from patients with familial adenomatous polyposis (FAP) produces DNA adducts when incubated with salmon sperm DNA in vitro. In the present study we have incubated the common primary and secondary, conjugated and unconjugated bile acids with salmon sperm DNA in vitro, in both the presence and absence of metabolic activation (Aroclor-induced rat liver S9). The DNA was then purified and assayed for the formation of DNA adducts using the nuclease P1 method of 32P-postlabelling. Under the conditions of the assay none of the bile acids tested with or without metabolic activation produced any evidence of DNA adduct formation. It is therefore unlikely that the adduct-forming ability of human bile can be attributed to bile acids or their metabolites.