Induction of a deoxycytidineless state in cultured mammalian cells by bromodeoxyuridine

Bromodeoxyuridine triphosphate is an allosteric inhibitor of ribonucleotide reductase, and bromodeoxyuridine can therefore kill cells by starving them for deoxycytidine nucleotides. The toxicity of bromodeoxyuridine for some cell lines is reduced many fold when deoxycytidine is also present. For example, wild type 3T6 cells can be grown serially in 1.5 × 10^?4 Molar bromodeoxyuridine and 2 × 10^?4 Molar deoxycytidine, remain healthy, and incorporate bromodeoxyuridine extensively into cellular DNA. Some of the numerous effects of this drug on the behavior of cells and viruses may be due to a deoxycytidineless state, rather than to the incorporation of the bromodeoxyuridine into DNA.