title: Stem cells with fused gene expression of cytosine deaminase and interferon-β             migrate to human gastric cancer cells and result in synergistic growth inhibition             for potential therapeutic use.
abstract: Genetically engineered stem cells (GESTECs) producing suicide enzymes and immunotherapeutic cytokines have therapeutic effects on tumors, and may possibly reduce the side effects of toxic drugs used for treatments. Suicide enzymes can convert non-toxic pro-drugs to toxic metabolites that can reduce tumor growth. Cytosine deaminase (CD) is a suicide enzyme that metabolizes a non-toxic pro-drug, 5-fluorocytosine (5-FC), into the cytotoxic agent, 5-fluorouracil (5-FU). As an immunotherapeutic agent, human interferon-β (IFN-β) has anticancer effects. In this study, we used modified human neural stem cells (HB1.F3) expressing the Escherichia coli (E. coli) CD gene (HB1.F3.CD) or both the CD and human IFN-β genes (HB1.F3.CD.IFN-β) and evaluated their effectiveness on gastric carcinoma cells (AGS); migration of GESTECs to AGS was analyzed as well as formation of 5-FU and IFN-β. Reverse transcription-polymerase chain reaction (RT-PCR) was used to confirm the expression of CD and IFN-β genes in GESTECs along with confirming the production of chemoattractant molecules such as stem cell factor (SCF), CXCR4, c-Kit, vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2). In addition, by co-culturing GESTECs with AGS in the presence of 5-FC, we were able to confirm that cancer growth was inhibited, along with a synergistic effect when the CD and IFN-β genes (HB1.F3.CD.IFN-β) were co-expressed. Indeed a marked anticancer effect was demonstrated when the CD and IFN-β genes were expressed together compared to expression of the CD gene alone (HB1.F3.CD). According to a modified transwell migration assay, the migration of GESTECs toward AGS was confirmed. In conclusion, these data suggest potential application of GESTECs to gastric cancer therapy, due to a remarkable synergistic effect of CD and IFN-β genes in the presence of 5-FC. Additionally, the tumor-selective migration capability in vitro suggests that GESTECs are a potential anticancer therapy candidate that may result in minimal side effects compared to the conventional chemotherapy.
authors.affiliation: Laboratory of Veterinary Biochemistry and Immunology, College                     of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk,                     Republic of Korea.
authors.forename: Kyoung-Yoon
authors.initials: KY
authors.lastname: Kim
authors.forename: Bo-Rim
authors.initials: BR
authors.lastname: Yi
authors.forename: Hye-Rim
authors.initials: HR
authors.lastname: Lee
authors.forename: Nam-Hee
authors.initials: NH
authors.lastname: Kang
authors.forename: Eui-Bae
authors.initials: EB
authors.lastname: Jeung
authors.forename: Seung U
authors.initials: SU
authors.lastname: Kim
authors.forename: Kyung-Chul
authors.initials: KC
authors.lastname: Choi
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D043525:Cytosine Deaminase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005818:Genetic Engineering; D015316:Genetic Therapy; D006801:Humans; D016899:Interferon-beta / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D014162:Transfection
chemical_list: D016899:Interferon-beta; D043525:Cytosine Deaminase