title: Induction of DNA ligase I by 1-beta-D-arabinosylcytosine and aphidicolin in MiaPaCa human pancreatic cancer cells.
abstract: Exposure of MiaPaCa cells to 1-beta-D-arabinosylcytosine (ara-C) resulted in an increase in DNA ligase levels up to threefold compared to that in the untreated control cells, despite significant growth inhibition. Increased levels of DNA ligase I protein appear to correlate with the appearance of increased mRNA levels. The [(3)H]thymidine incorporation experiment and the biochemical assay of total polymerase activity revealed that an increase in DNA ligase I levels after treatment with ara-C was not accompanied by an increase of DNA synthesis or an increased presence of DNA polymerase activity inside cells. When cells resumed DNA synthesis after drug treatment, DNA ligase I levels began to drop, indicating that increased DNA ligase I is not required for DNA synthesis. An increase in DNA ligase I was also observed in cells treated with aphidicolin, another inhibitor of DNA synthesis that inhibits DNA polymerases without incorporating itself into DNA, indicating that an increase in DNA ligase I levels could be caused by the arrest of DNA replication by these agents. Interestingly, caffeine, which is a well-known inhibitor of DNA damage checkpoint kinases, abrogated the increase in DNA ligase I in MiaPaCa cells treated with ara-C and aphidicolin, suggesting that caffeine-sensitive kinases might be important mediators in the pathway leading to the increase in DNA ligase I levels in response to anticancer drugs, including ara-C and aphidicolin. We propose that ara-C and aphidicolin induce damage to the DNA strand by arresting DNA replication forks and subsequently increase DNA ligase I levels to facilitate repair of DNA damage.
authors.affiliation: Institute for Drug Development, Cancer Therapy and Research Center, San Antonio, Texas 78245, USA. sun@pharmacy.arizona.edu
authors.forename: Daekyu
authors.initials: D
authors.lastname: Sun
authors.forename: Rheanna
authors.initials: R
authors.lastname: Urrabaz
authors.forename: Christoph
authors.initials: C
authors.lastname: Buzello
authors.forename: Myhanh
authors.initials: M
authors.lastname: Nguyen
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000493:pharmacokinetics / Q000494:pharmacology*; D016590:Aphidicolin / Q000493:pharmacokinetics / Q000494:pharmacology*; D002110:Caffeine / Q000494:pharmacology; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003561:Cytarabine / Q000493:pharmacokinetics / Q000494:pharmacology*; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000096:biosynthesis* / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects; D004273:DNA, Neoplasm / Q000096:biosynthesis; D004259:DNA-Directed DNA Polymerase / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology*; D006801:Humans; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010190:Pancreatic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000964:Antimetabolites, Antineoplastic; D004273:DNA, Neoplasm; D004791:Enzyme Inhibitors; C000607892:LIG1 protein, human; D019384:Nucleic Acid Synthesis Inhibitors; D010726:Phosphodiesterase Inhibitors; D012333:RNA, Messenger; D003561:Cytarabine; D016590:Aphidicolin; D002110:Caffeine; D004259:DNA-Directed DNA Polymerase; D011088:DNA Ligases; D000072481:DNA Ligase ATP