title: Cytosine deaminase-producing human mesenchymal stem cells mediate an antitumor effect in a mouse xenograft model.
abstract: OBJECTIVE
  Stem cell transplantation offers potential gene therapy for brain tumors. However, this approach has received little attention as a treatment for gastrointestinal tumors. In the present study, we explored the possibility of human bone marrow-derived mesenchymal stem cells (hMSC) producing cytosine deaminase (CD), followed by systemic 5-fluorocytosine (5-FC) administration, showing an antitumor effect on a mouse gastric cancer xenograft.
  
  
  METHODS
  We first explored the ability of hMSC, coated with fluorescent dye, to migrate to human gastric cancer MKN45 cells in vitro and in vivo. We then used hMSC in which a gene expressed the prodrug-activating enzyme CD, which can convert the prodrug 5-FC into the cytotoxic agent 5-fluorouracil (5-FU), and further investigated the potential of these cells to deliver the CD gene and to reduce tumor growth in nude mice. The migratory capacity of hMSC was confirmed by an in vitro migration assay, as well as in an in vivo model of nude mice bearing subcutaneous tumors of MKN45 cells when hMSC were injected.
  
  
  RESULTS
  The migration ability of hMSC towards MKN45 cells was confirmed by migration assay. Effective conversion of 5-FC to 5-FU by hMSC transfected with the CD gene (CD-hMSC) showed therapeutic anticancer potential in a MKN45 cell co-culture system, as confirmed by thin layer chromatography. Nude mice bearing MKN45 tumors were intravenously injected with CD-hMSC, followed by systemic 5-FC treatment (500 mg/kg/day) for 7 days. Tumor volumes and weights of mice injected with CD-hMSC decreased significantly after treatment with 5-FC. However, the 5-FC-treated group without CD-hMSC injection showed neither a decrease in tumor volume nor bodyweight loss.
  
  
  CONCLUSIONS
  The CD-hMSC system showed anticancer therapeutic potential, and minimized the side-effects of 5-FU.
authors.affiliation: Department of Veterinary Pathology, Seoul National University, Seoul, Korea.
authors.forename: Mi-Hyeon
authors.initials: MH
authors.lastname: You
authors.forename: Wang-Joon
authors.initials: WJ
authors.lastname: Kim
authors.forename: Wooyoung
authors.initials: W
authors.lastname: Shim
authors.forename: Sang-Rim
authors.initials: SR
authors.lastname: Lee
authors.forename: Gwang
authors.initials: G
authors.lastname: Lee
authors.forename: Sangdun
authors.initials: S
authors.lastname: Choi
authors.forename: Dae-Yong
authors.initials: DY
authors.lastname: Kim
authors.forename: Yong Man
authors.initials: YM
authors.lastname: Kim
authors.forename: Hyunsoo
authors.initials: H
authors.lastname: Kim
authors.forename: Sang-Uk
authors.initials: SU
authors.lastname: Han
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage* / Q000378:metabolism; D002232:Carbocyanines; D045744:Cell Line, Tumor; D002465:Cell Movement; D043525:Cytosine Deaminase / Q000096:biosynthesis* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005437:Flucytosine / Q000008:administration & dosage* / Q000378:metabolism; D005456:Fluorescent Dyes; D005472:Fluorouracil / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D007274:Injections, Intraperitoneal; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000201:enzymology*; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D011355:Prodrugs / Q000008:administration & dosage* / Q000378:metabolism; D013274:Stomach Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D013997:Time Factors; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: C434385:3,3'-dioactadecyl-5,5'-di(4-sulfophenyl)oxacarbocyanine; D000964:Antimetabolites, Antineoplastic; D002232:Carbocyanines; D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D011355:Prodrugs; D005437:Flucytosine; D043525:Cytosine Deaminase; C468827:codA protein, E coli; D005472:Fluorouracil