title: A novel action of human apurinic/apyrimidinic endonuclease: excision of L-configuration deoxyribonucleoside analogs from the 3' termini of DNA.
abstract: beta-l-Dioxolane-cytidine (l-OddC, BCH-4556, Troxacitabine) is a novel unnatural stereochemical nucleoside analog that is under phase II clinical study for cancer treatment. This nucleoside analog could be phosphorylated and subsequently incorporated into the 3' terminus of DNA. The cytotoxicity of l-OddC was correlated with the amount of l-OddCMP in DNA, which depends on the incorporation by DNA polymerases and the removal by exonucleases. Here we reported the purification and identification of the major enzyme that could preferentially remove l-OddCMP compared with dCMP from the 3' termini of DNA in human cells. Surprisingly, this enzyme was found to be apurinic/apyrimidinic endonuclease (APE1) (), a well characterized DNA base excision repair protein. APE1 preferred to remove l- over d-configuration nucleosides from 3' termini of DNA. The efficiency of removal of these deoxycytidine analogs were as follows: l-OddC > beta-l-2',3'-dideoxy-2', 3'-didehydro-5-fluorocytidine > beta-l-2',3'-dideoxycytidine > beta-l-2',3'-dideoxy-3'-thiocytidine > beta-d-2',3'-dideoxycytidine > beta-d-2',2'-difluorodeoxycytidine > beta-d-2'-deoxycytidine >/= beta-d-arabinofuranosylcytosine. This report is the first demonstration that an exonuclease can preferentially excise l-configuration nucleoside analogs. This discovery suggests that APE1 could be critical for the activity of l-OddC or other l-nucleoside analogs and may play additional important roles in cells that were not previously known.
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Chou
authors.forename: M
authors.initials: M
authors.lastname: Kukhanova
authors.forename: Y C
authors.initials: YC
authors.lastname: Cheng
mesh_terms: D000838:Anions; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology*; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology; D015153:Blotting, Western; D019757:Carbon-Oxygen Lyases / Q000737:chemistry* / Q000502:physiology*; D002412:Cations; D002847:Chromatography, Agarose; D002852:Chromatography, Ion Exchange; D003561:Cytarabine / Q000737:chemistry / Q000494:pharmacology; D003596:Cytosine / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D003843:Deoxycytidine Monophosphate / Q000378:metabolism; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004148:Dioxolanes / Q000737:chemistry* / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004720:Endonucleases / Q000378:metabolism; D006801:Humans; D009841:Oligonucleotides / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry / Q000494:pharmacology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism; D013872:Thionucleosides / Q000737:chemistry / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D016047:Zalcitabine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
chemical_list: C120719:2'-deoxy-3'-oxa-thiocytidine; D000838:Anions; D000970:Antineoplastic Agents; D000998:Antiviral Agents; D002412:Cations; D004148:Dioxolanes; D009841:Oligonucleotides; D011994:Recombinant Proteins; D018894:Reverse Transcriptase Inhibitors; D013872:Thionucleosides; D003561:Cytarabine; D003841:Deoxycytidine; D003843:Deoxycytidine Monophosphate; C074908:troxacitabine; D016047:Zalcitabine; D003596:Cytosine; D004247:DNA; D004720:Endonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); D019757:Carbon-Oxygen Lyases; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; C099405:dexelvucitabine