Genetically modified Chinese hamster ovary cells for investigating sulfotransferase-mediated cytotoxicity and mutation by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine

To test the hypothesis that the sulfotransferase gene plays a role in the p hase II bioactivation of PhlP, a heterocyclic amine found in cooked meats, we transfected the UV5P3 cell line with cDNA plasmids of human aryl sulfotr ansferases (HAST1 and MASTS). UV5P3 is a nucleotide excision repair-deficie nt and P4501A2-expressing CHO cell line that we have previously developed. Functionally transformed clones were identified by the differential cytotox icity (DC) assay that used PhlP as the cytotoxic agent. Two clones designat ed 5P3H1 and 5P3H3, expressing HAST1 and HAST3, respectively, were chosen f or further characterization. Correct fragment sizes of the sulfotransferase cDNAs were identified in both cell lines by polymerase chain reaction. Imm unoblot analysis confirmed the expression of the sulfotransferase proteins. The addition of the sulfotransferase inhibitor DCNP decreased the cytotoxi c effects of PhlP in a dose-dependent manner. The increase in cell growth w as 6.5-fold for 5P3H1 and 2.4-fold for 5P3H3, relative to values obtained w ithout DCNP. Based on D-50 values, the dose that reduced the survival to 50 % relative to untreated controls, the cytotoxic effect of PhlP was increase d threefold For 5P3H1 and 1.87-fold for 5P3H3 cell lines over the parental UV5P3 line. There was also a small increase in the mutation response at the aprt locus. These newly established 5P3H1 and 5P3H3 sulfotransferase-expre ssing cells provide valuable mechanistic information of the bioactivation o f PhlP and related compounds. Published 2000 Wiley-Liss, Inc.(dagger).