Differential cytotoxicity between transformed and normal human cells with combinations of aminonucleoside and hydroxyurea.

Normal human WI-38 cells can be protected from killing by hydroxyurea if proliferation is arrested during drug treatment. This protection was demonstrated both in cells arrested by density-dependent inhibition and by 3'-amino-3'deoxy-N6,N6-dimethyladenosine (puromycin aminonucleoside). In contrast, VA-13 cells (a simian virus 40-transformed clone of WI-38) were not arrested under these conditions, and continued to be sensitive to hydroxyurea. These results suggest that a search for agents that selectively and reversibly inhibit normal cycling human cells might lead to an enhancement of differential tumor toxicity.