title: Adenosine potentiates the therapeutic effects of neural stem cells expressing cytosine deaminase against metastatic brain tumors.
abstract: Tumor-tropic properties of neural stem cells (NSCs) provide a novel approach with which to deliver targeting therapeutic genes to brain tumors. Previously, we developed a therapeutic strategy against metastatic brain tumors using a human NSC line (F3) expressing cytosine deaminase (F3.CD). F3.CD converts systemically administered 5-fluorocytosine (5-FC), a blood-brain barrier permeable nontoxic prodrug, into the anticancer agent 5-fluorouracil (5-FU). In this study, we potentiated a therapeutic strategy of treatment with nucleosides in order to chemically facilitate the endogenous conversion of 5-FU to its toxic metabolite 5-FU ribonucleoside (5-FUR). In vitro, 5-FUR showed superior cytotoxic activity against MDA-MB-435 cancer cells when compared to 5-FU. Although adenosine had little cytotoxic activity, the addition of adenosine significantly potentiated the in vitro cytotoxicity of 5-FU. When MDA-MB‑435 cells were co-cultured with F3.CD cells, F3.CD cells and 5-FC inhibited the growth of MDA-MB-435 cells more significantly in the presence of adenosine. Facilitated 5-FUR production by F3.CD was confirmed by an HPLC analysis of the conditioned media derived from F3.CD cells treated with 5-FC and adenosine. In vivo systemic adenosine treatment also significantly potentiated the therapeutic effects of F3.CD cells and 5-FC in an MDA-MB-435 metastatic brain tumor model. Simple adenosine addition improved the antitumor activity of the NSCs carrying the therapeutic gene. Our results demonstrated an increased therapeutic potential, and thereby, clinical applicability of NSC-based gene therapy.
authors.affiliation: Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Wonyoung
authors.initials: W
authors.lastname: Kang
authors.forename: Ho Jun
authors.initials: HJ
authors.lastname: Seol
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Seong
authors.forename: Jandi
authors.initials: J
authors.lastname: Kim
authors.forename: Yonghyun
authors.initials: Y
authors.lastname: Kim
authors.forename: Seung U
authors.initials: SU
authors.lastname: Kim
authors.forename: Do-Hyun
authors.initials: DH
authors.lastname: Nam
authors.forename: Kyeung Min
authors.initials: KM
authors.lastname: Joo
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001812:Blood-Brain Barrier / Q000187:drug effects; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology / Q000556:secondary; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D043525:Cytosine Deaminase / Q000235:genetics / Q000378:metabolism*; D004357:Drug Synergism; D005260:Female; D005333:Fetus / Q000187:drug effects / Q000201:enzymology; D005437:Flucytosine / Q000378:metabolism; D005472:Fluorouracil / Q000494:pharmacology*; D005818:Genetic Engineering; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D058953:Neural Stem Cells / Q000187:drug effects / Q000201:enzymology*; D011355:Prodrugs / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000964:Antimetabolites, Antineoplastic; D011355:Prodrugs; D014665:Vasodilator Agents; D005437:Flucytosine; D043525:Cytosine Deaminase; D000241:Adenosine; D005472:Fluorouracil