title: A cell surface tethered enzyme improves efficiency in gene-directed enzyme prodrug therapy.
abstract: The potential for expressing the bacterial enzyme carboxypeptidase G2 (CPG2) tethered to the outer surface of mammalian cells was examined for use in gene-directed enzyme prodrug therapy. The affinity of CPG2 for the substrate methotrexate was unaffected by three mutations required to prevent N-linked glycosylation. Breast carcinoma MDA MB 361 cells expressing CPG2 internally showed only a very modest increase in sensitivity to the prodrug CMDA because the prodrug did not enter the cells. Cells expressing surface-tethered CPG2, however, became 16-24-fold more sensitive to CMDA and could mount a good bystander effect. Systemic administration of CMDA to mice bearing established xenografts of the transfected cells led to sustained tumor regressions or cures.
authors.affiliation: CRC Centre for Cancer Therapeutics, Institute of Cancer Research, Sutton, Surrey, UK.
authors.forename: R
authors.initials: R
authors.lastname: Marais
authors.forename: R A
authors.initials: RA
authors.lastname: Spooner
authors.forename: S M
authors.initials: SM
authors.lastname: Stribbling
authors.forename: Y
authors.initials: Y
authors.lastname: Light
authors.forename: J
authors.initials: J
authors.lastname: Martin
authors.forename: C J
authors.initials: CJ
authors.lastname: Springer
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000737:chemistry / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D016503:Drug Delivery Systems; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005971:Glutamates / Q000737:chemistry / Q000494:pharmacology*; D006031:Glycosylation; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis*; D008727:Methotrexate / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D008819:Mice, Nude; D009154:Mutation / Q000235:genetics; D009368:Neoplasm Transplantation; D009588:Nitrogen Mustard Compounds / Q000737:chemistry / Q000494:pharmacology*; D011355:Prodrugs / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects; D011623:gamma-Glutamyl Hydrolase / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D005971:Glutamates; D008565:Membrane Proteins; D009588:Nitrogen Mustard Compounds; D011355:Prodrugs; C092574:4-((2-chloroethyl)(2-mesyloxyethyl)amino)benzoylglutamic acid; D011623:gamma-Glutamyl Hydrolase; D008727:Methotrexate