title: Gemcitabine diphosphate choline is a major metabolite linked to the Kennedy pathway in pancreatic cancer models in vivo.
abstract: BACKGROUND
  The modest benefits of gemcitabine (dFdC) therapy in patients with pancreatic ductal adenocarcinoma (PDAC) are well documented, with drug delivery and metabolic lability cited as important contributing factors. We have used a mouse model of PDAC: KRAS(G12D); p53(R172H); pdx-Cre (KPC) that recapitulates the human disease to study dFdC intra-tumoural metabolism.
  
  
  METHODS
  LC-MS/MS and NMR were used to measure drug and physiological analytes. Cytotoxicity was assessed by the Sulphorhodamine B assay.
  
  
  RESULTS
  In KPC tumour tissue, we identified a new, Kennedy pathway-linked dFdC metabolite (gemcitabine diphosphate choline (GdPC)) present at equimolar amounts to its precursor, the accepted active metabolite gemcitabine triphosphate (dFdCTP). Utilising additional subcutaneous PDAC tumour models, we demonstrated an inverse correlation between GdPC/dFdCTP ratios and cytidine triphosphate (CTP). In tumour homogenates in vitro, CTP inhibited GdPC formation from dFdCTP, indicating competition between CTP and dFdCTP for CTP:phosphocholine cytidylyltransferase (CCT). As the structure of GdPC precludes entry into cells, potential cytotoxicity was assessed by stimulating CCT activity using linoleate in KPC cells in vitro, leading to increased GdPC concentration and synergistic growth inhibition after dFdC addition.
  
  
  CONCLUSIONS
  GdPC is an important element of the intra-tumoural dFdC metabolic pathway in vivo.
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: T E
authors.initials: TE
authors.lastname: Bapiro
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: K K
authors.initials: KK
authors.lastname: Frese
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: A
authors.initials: A
authors.lastname: Courtin
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Bramhall
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: B
authors.initials: B
authors.lastname: Madhu
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: N
authors.initials: N
authors.lastname: Cook
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: A
authors.initials: A
authors.lastname: Neesse
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Griffiths
authors.affiliation: Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Tuveson
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: D I
authors.initials: DI
authors.lastname: Jodrell
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Box 278, Robinson Way, Cambridge CB2 0RE, UK.
authors.forename: F M
authors.initials: FM
authors.lastname: Richards
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000493:pharmacokinetics / Q000494:pharmacology; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy* / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology; D011756:Diphosphates / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D011756:Diphosphates; D003841:Deoxycytidine; D002794:Choline; D000093542:Gemcitabine