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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3T3 Cells
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Animals
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Antimetabolites, Antineoplastic / chemistry
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Antimetabolites, Antineoplastic / pharmacology
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Antineoplastic Agents / pharmacology*
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Breast Neoplasms / drug therapy*
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Breast Neoplasms / pathology
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Drug Delivery Systems*
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Female
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Gene Expression Regulation, Enzymologic / genetics
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Glutamates / chemistry
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Glutamates / pharmacology*
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Glycosylation
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Humans
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Membrane Proteins / biosynthesis*
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Methotrexate / chemistry
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Methotrexate / pharmacology
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Mice
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Mice, Nude
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Mutation / genetics
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Neoplasm Transplantation
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Nitrogen Mustard Compounds / chemistry
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Nitrogen Mustard Compounds / pharmacology*
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Prodrugs / pharmacology*
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Transfection
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Tumor Cells, Cultured / drug effects
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gamma-Glutamyl Hydrolase / biosynthesis*
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gamma-Glutamyl Hydrolase / chemistry
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gamma-Glutamyl Hydrolase / pharmacology*
Substances
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Antimetabolites, Antineoplastic
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Antineoplastic Agents
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Glutamates
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Membrane Proteins
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Nitrogen Mustard Compounds
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Prodrugs
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4-((2-chloroethyl)(2-mesyloxyethyl)amino)benzoylglutamic acid
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gamma-Glutamyl Hydrolase
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Methotrexate