Specific inhibition of DNA biosynthesis induced by 3'-amino-2',3'-dideoxycytidine

• Published in: Biochemistry (Easton) Vol. 27; no. 24; pp. 8832 - 8839
• Main Authors: Mancini, William R, Williams, Mark S, Lin, Tai Shun
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.11.1988
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Antineoplastic Agents - pharmacology; Biological and medical sciences; Carcinoma, Ehrlich Tumor - metabolism; Dideoxynucleosides - chemical synthesis; Dideoxynucleosides - pharmacology; Dideoxynucleosides - therapeutic use; DNA Polymerase II - metabolism; DNA Replication - drug effects; Dna, deoxyribonucleoproteins; DNA, Neoplasm - biosynthesis; DNA, Neoplasm - drug effects; Flow Cytometry; Fundamental and applied biological sciences. Psychology; Kinetics; Leukemia L1210 - drug therapy; Leukemia L1210 - enzymology; Mice; Nucleic acids; Tumor Cells, Cultured - cytology; Tumor Cells, Cultured - drug effects; Tumor Cells, Cultured - metabolism; Zalcitabine - analogs & derivatives; Density gradient centrifugation; Flow cytometry; Cell death; Cell cycle; Reaction inhibition; Inhibition constant; DNA synthesis
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00424a022

3'-Amino-2',3'-dideoxycytidine (3'-NH2-dCyd) produced an S-phase-specific block in exponentially growing L1210 leukemia cells. The monophosphate and triphosphate forms of the drug were detected within a few hours of 3'-NH2-dCyd treatment of intact cells. No significant change in the deoxynucleoside triphosphate levels was observed during the early stages of treatment. However, by 24 h a 2-fold increase in the amount of the deoxynucleoside triphosphates was seen. The triphosphate form of the drug competitively inhibited dCTP incorporation into calf thymus DNA using highly purified DNA polymerase alpha. The Ki was determined to be 9.6 microM with respect to dCTP. Incorporation of the analogue into DNA was not detected. On the other hand, sucrose gradient analysis suggested that incorporation of the analogue into actively synthesized DNA may account for the biological activity of this compound. Treatment with 3'-NH2-dCyd induced single-strand breaks in actively synthesized DNA, but no double-strand breaks were observed in the presence of the analogue. The data indicate that 3'-amino-2',3'-dideoxycytidine specifically interferes with DNA replication at the level of DNA polymerase by inhibiting chain elongation.