Replication-dependent irreversible topoisomerase 1 poisoning is responsible for FdUMP[10] anti-leukemic activity.

Abstract

Previous studies have indicated that 5-Fluoro-2'-deoxyuridine-5'-O-monophosphate 10mer (FdUMP[10]) displays strong antileukemic activity through the dual targeting of thymidylate synthase (TS) and DNA topoisomerase 1 (Top1). The present studies were undertaken to clarify the relationship between the induction of a thymineless state and the formation of Top1 cleavage complexes (Top1CC) for inducing cell death and to clarify the role of DNA replication for induction of lethal DNA double-strand breaks (DSBs) in FdUMP[10]-treated acute myeloid leukemia (AML) cells. Human promyelocytic (HL60) and AML (KG1a, Molm13, THP-1) cells were synchronized by serum starvation and treated with FdUMP[10] with thymidine (Thy) rescue. Cells were assayed for TS inhibition, DNA DSBs, Top1CC, and apoptosis to clarify the interrelationship of TS inhibition and Top1CC for cell death. FdUMP[10] induced a thymineless state in AML cells and exogenous Thy administered within the first 18 hours of treatment rescued FdUMP[10]-induced Top1CC formation, γH2AX phosphorylation, and apoptosis induction. Exogenous Thy was not effective after cells had committed to mitosis and undergone cell division in the presence of FdUMP[10]. FdUMP[10] treatment resulted in Chk1 activation, and Chk1 inhibition enhanced FdUMP[10]-induced DNA damage and apoptosis. Jnk-signaling was required for FdUMP[10]-induced apoptosis in promyelocytic HL60 cells and in THP1 cells, but was antiapoptotic in Molm13 and to a lesser extent KG1a AML cells. The results are consistent with FdUMP[10] inducing a thymineless state, leading to misincorporation of FdU into genomic DNA of proliferating cells. Top1CC form in cells upon re-entry into S-phase, resulting in DNA double-strand breaks, and initiating apoptotic signaling that can be either muted or enhanced by Jnk-signaling depending on cell type.

• Authors: Jamie Jennings-Gee, Timothy S Pardee, William H Gmeiner
• Journal: Experimental hematology (Exp Hematol) Vol. 41 Issue 2 Pg. 180-188.e4 (Feb 2013) ISSN: 1873-2399 [Electronic] Netherlands
• PMID: 23085462 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2013 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.

Chemical References

• Alkaloids
• Antimetabolites, Antineoplastic
• DNA, Neoplasm
• Topoisomerase Inhibitors
• Fluorodeoxyuridylate
• Thymidylate Synthase
• DNA Topoisomerases, Type I
• TOP1 protein, human
• Thymine
• SB 218078

Topics

• Alkaloids (pharmacology)
• Antimetabolites, Antineoplastic (pharmacology)
• Apoptosis (drug effects)
• Cell Cycle Checkpoints (drug effects)
• Cell Line, Tumor (drug effects)
• DNA Breaks, Double-Stranded (drug effects)
• DNA Replication (drug effects)
• DNA Topoisomerases, Type I (physiology)
• DNA, Neoplasm (metabolism)
• Fluorodeoxyuridylate (pharmacology)
• HL-60 Cells (drug effects)
• Humans
• Leukemia, Monocytic, Acute (pathology)
• Leukemia, Promyelocytic, Acute (pathology)
• S Phase (drug effects)
• Thymidylate Synthase (antagonists & inhibitors)
• Thymine (metabolism, pharmacology)
• Topoisomerase Inhibitors (pharmacology)