title: Monogalactosyl diacylglycerol, a replicative DNA polymerase inhibitor, from spinach enhances the anti-cell proliferation effect of gemcitabine in human pancreatic cancer cells.
abstract: BACKGROUND
  Gemcitabine (GEM) is used to treat various carcinomas and represents an advance in pancreatic cancer treatment. In the screening for DNA polymerase (pol) inhibitors, a glycoglycerolipid, monogalactosyl diacylglycerol (MGDG), was isolated from spinach.
  
  
  METHODS
  Phosphorylated GEM derivatives were chemically synthesized. In vitro pol assay was performed according to our established methods. Cell viability was measured using MTT assay.
  
  
  RESULTS
  Phosphorylated GEMs inhibition of mammalian pol activities assessed, with the order of their effect ranked as: GEM-5'-triphosphate (GEM-TP) > GEM-5'-diphosphate > GEM-5'-monophosphate > GEM. GEM suppressed growth in the human pancreatic cancer cell lines BxPC-3, MIAPaCa2 and PANC-1 although phospholylated GEMs showed no effect MGDG suppressed growth in these cell lines based on its selective inhibition of replicative pol species. Kinetic analysis showed that GEM-TP was a competitive inhibitor of pol alpha activity with nucleotide substrates, and MGDG was a noncompetitive inhibitor with nucleotide substrates. GEM combined with MGDG treatments revealed synergistic effects on the inhibition of DNA replicative pols alpha and gamma activities compared with GEM or MGDG alone. In cell growth suppression by GEM, pre-addition of MGDG significantly enhanced cell proliferation suppression, and the combination of these compounds was found to induce apoptosis. In contrast, GEM-treated cells followed by MGDG addition did not influence cell growth.
  
  
  CONCLUSIONS
  GEM/MGDG enhanced the growth suppression of cells based on the inhibition of pol activities.
  
  
  CONCLUSIONS
  Spinach MGDG has great potential for development as an anticancer food compound and could be an effective clinical anticancer chemotherapy in combination with GEM.
authors.affiliation: Division of Radiation Oncology, Kobe University Graduate School of Medicine, Chuo-ku Kobe, Hyogo 650-0017, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Akasaka
authors.forename: Ryohei
authors.initials: R
authors.lastname: Sasaki
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoshida
authors.forename: Izumi
authors.initials: I
authors.lastname: Takayama
authors.forename: Toyofumi
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yoshida
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Mizushina
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000737:chemistry / Q000494:pharmacology; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D002417:Cattle; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D038983:Galactolipids / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010936:Plant Extracts / Q000737:chemistry; D051381:Rats; D018724:Spinacia oleracea / Q000737:chemistry*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D004791:Enzyme Inhibitors; D038983:Galactolipids; D007527:Isoenzymes; D009363:Neoplasm Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D010936:Plant Extracts; C009909:monogalactosyldiacylglycerol; D003841:Deoxycytidine; D004259:DNA-Directed DNA Polymerase; D000093542:Gemcitabine