Cell kinetic disturbances induced by treatment of human diploid fibroblasts with 5-azacytidine indicate a major role for DNA methylation in the regulation of the chromosome cycle.
BrdU-Hoechst flow cytometry was used to investigate the effects of DNA hypomethylation, induced by treatment with 5-azacytidine (5AC), on cell proliferation. When human fibroblast-like cells derived from skin and amniotic fluid were exposed to 5AC during three successive cell cycles, their clone-forming ability was diminished after removal of the drug. Treated cells were rendered quiescent by culture with low serum in the absence of the drug. Upon serum stimulation, they showed a diminished fraction of proliferating cells, which exhibited a prolonged transit through the S and G2 phase of the cell cycle, and a permanent arrest within the G2 compartment. This pattern of disturbed cell proliferation may in part explain the changes in replication banding pattern reported in the literature. Cytogenetic analysis of 5AC-treated cells revealed numerous endomitoses and tetraploid metaphases indicating a disturbed chromosome cycle in association with these cell kinetic perturbations.
Institut für Humangenetik der Universität, Würzburg, Federal Republic of Germany.
M
M
Poot
J
J
Koehler
P S
PS
Rabinovitch
H
H
Hoehn
J H
JH
Priest
D001374:Azacitidine / Q000633:toxicity*; D006690:Bisbenzimidazole; D001973:Bromodeoxyuridine; D002453:Cell Cycle / Q000187:drug effects*; D002478:Cells, Cultured; D004247:DNA / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D005434:Flow Cytometry; D006801:Humans; D008745:Methylation
D004247:DNA; D001973:Bromodeoxyuridine; D006690:Bisbenzimidazole; D001374:Azacitidine