Inhibition of Friend erythroleukemic cell differentiation by bromodeoxyuridine: correlation with the amount of bromodeoxyuridine in DNA.

These studies were undertaken to examine the relationship between the inhibition by 5-bromodeoxyuridine (BrdU) of erythroid differentiation in Friend erythroleukemia cells and the incorporation of BrdU into DNA. Experiments were carried out in which the incorporation of BrdU into DNA and the concentration of BrdU to which the cells were exposed were varied independently of each other. In addition, the ability of deoxycytidine (dC) to reverse the effects of BrdU on hemoglobin production and to reduce the amount of BrdU in DNA was analyzed. Under all the conditions tested, the effects of BrdU were correlated with the amount of BrdU incorporated into nuclear DNA. These results differ from those of recent studies on the inhibition of pigmentation and the induction of mutations by BrdU in Syrian hamster melanoma cells. The results suggest that BrdU may be producing its biological effects by a variety of different mechanisms.