Termination of DNA synthesis by 9-beta-D-arabinofuranosyl-2-fluoroadenine. A mechanism for cytotoxicity.
The action of 9-beta-D-arabinofuranosyl-2-fluoroadenine (F-ara-A) on DNA synthesis was evaluated both in whole cells and in vitro. 9-beta-D-Arabinofuranosyl-2-fluoroadenine was converted to its 5'-triphosphate 9-beta-D-arabinofuranosyl-2-fluoroadenine 5'-triphosphate (F-ara-ATP) in cells and then incorporated into DNA in a self-limiting manner. More than 94% of the analogue was incorporated into DNA at the 3' termini, indicating a chain termination action. In vitro DNA primer extension experiments further revealed that F-ara-ATP compared with dATP for incorporation into the A site of the extending DNA strand. The incorporation of F-ara-AMP into DNA resulted in termination of DNA strand elongation. Human DNA polymerase alpha incorporated more F-ara-AMP into DNA than polymerase epsilon (proliferating cell nuclear antigen-independent DNA polymerase delta) and was more sensitive to inhibition by F-ara-ATP. On the other hand, DNA polymerase epsilon was able to excise the incorporated F-ara-AMP from DNA in vitro. The incorporation of F-ara-AMP into DNA was linearly correlated both with inhibition of DNA synthesis and with loss of clonogenicity; thus it may be the mechanism of cytotoxicity.
Huang
P
P
Department of Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston.
Chubb
S
S
Plunkett
W
W
D016590:Aphidicolin; D001088:Arabinonucleotides / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D002999:Clone Cells; D004261:DNA Replication / Q000187:drug effects*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004224:Diterpenes / Q000494:pharmacology; D006157:Guanosine Monophosphate / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D019384:Nucleic Acid Synthesis Inhibitors; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001084:Vidarabine Phosphate / Q000031:analogs & derivatives / Q000378:metabolism
D001088:Arabinonucleotides; D004224:Diterpenes; D019384:Nucleic Acid Synthesis Inhibitors; D001084:Vidarabine Phosphate; C042382:fludarabine phosphate; D016590:Aphidicolin; C034957:2-fluoro-araATP; D006157:Guanosine Monophosphate; D004259:DNA-Directed DNA Polymerase; D014740:Vidarabine; C024352:fludarabine