title: Activation of p16 gene silenced by DNA methylation in cancer cells by phosphoramidate derivatives of 2'-deoxyzebularine.
abstract: We report herein the application of the phosphoramidate ProTide technology to improve the metabolism of the DNA methytransferase inhibitor, zebularine (Z). Zebularine is a riboside that must undergo a complex metabolic transformation before reaching the critical 2'-deoxyzebularine 5'-triphosphate (dZTP). Because 2'-deoxyzebularine (dZ) is not phosphorylated and therefore inactive, the ProTide strategy was employed to bypass the lack of phosphorylation of dZ and the inefficient reduction of zebularine 5'-diphosphate by ribonucleotide-diphosphate reductase required for zebularine. Several compounds were identified as more potent inhibitors of DNA methylation and stronger inducers of p16 tumor suppressor gene than zebularine. However, their activity was dependent on the administration of thymidine to overcome the potent inhibition of thymidylate synthase (TS) and deoxycytidine monophosphate (dCMP) deaminase by dZMP, which deprives cells of essential levels of thymidine. Intriguingly, the activity of the ProTides was cell line-dependent, and activation of p16 was manifest only in Cf-Pac-1 pancreatic ductal adenocarcinoma cells.
authors.affiliation: Department of Biochemistry, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
authors.forename: Christine B
authors.initials: CB
authors.lastname: Yoo
authors.forename: Rocco
authors.initials: R
authors.lastname: Valente
authors.forename: Costantino
authors.initials: C
authors.lastname: Congiatu
authors.forename: Federica
authors.initials: F
authors.lastname: Gavazza
authors.forename: Annette
authors.initials: A
authors.lastname: Angel
authors.forename: Maqbool A
authors.initials: MA
authors.lastname: Siddiqui
authors.forename: Peter A
authors.initials: PA
authors.lastname: Jones
authors.forename: Christopher
authors.initials: C
authors.lastname: McGuigan
authors.forename: Victor E
authors.initials: VE
authors.lastname: Marquez
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000577:Amides / Q000737:chemistry*; D003562:Cytidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D003844:DCMP Deaminase / Q000037:antagonists & inhibitors; D019175:DNA Methylation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D020868:Gene Silencing / Q000187:drug effects*; D019942:Genes, p16 / Q000187:drug effects*; D006801:Humans; D015394:Molecular Structure; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010756:Phosphoric Acids / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013237:Stereoisomerism; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors; D014407:Tumor Cells, Cultured
chemical_list: D000577:Amides; D010756:Phosphoric Acids; D003562:Cytidine; C009131:pyrimidin-2-one beta-ribofuranoside; C011067:phosphoramidic acid; D013940:Thymidylate Synthase; D003844:DCMP Deaminase