Unscheduled DNA synthesis after treatment with 20-methylcholanthrene and N-nitrosodimethylamine in primary culture of human gallbladder epithelial cells.

Unscheduled DNA synthesis (UDS) induced by treatment with 20-methylcholanthrene (MCA) and N-nitrosodimethylamine (DMN) was measured in cultured human gallbladder epithelial cells. MCA induced UDS very efficiently, while DMN was far less effective than MCA. Addition of rat S9 mixture did not affect the amount of UDS by the chemicals. Differences between the present results in human cells and our previous findings in bovine cells could be due to species and tissue specificity.