title: Dihydrofolate reductase mutant with exceptional resistance to methotrexate but not to trimetrexate.
abstract: Two double (F31A/F34A, I60A/L67G) and one quadruple (F31A/F34A/I60A/L67G) mutant murine dihydrofolate reductases were constructed and evaluated for their ability to impart antifolate resistance. Both I60A/L67G and F31A/F34A/I60A/L67G were found to be unstable and devoid of catalytic activity. The K(i) values for F31A/F34A, methotrexate (MTX), bis-MTX, and PT-523 were found to be 10100-, 4410-, and 617-fold higher than the wild-type enzyme, respectively, but only 13.5-fold higher for trimetrexate (TMTX). These findings suggest that F31A/F34A could be used for gene therapy to render normal cells resistant to MTX but sensitive to TMTX.
authors.affiliation: Departments of Medicinal Chemistry and of Genetics and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Pamela
authors.initials: P
authors.lastname: Pineda
authors.forename: Aaron
authors.initials: A
authors.lastname: Kanter
authors.forename: R Scott
authors.initials: RS
authors.lastname: McIvor
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Benkovic
authors.forename: Andre
authors.initials: A
authors.lastname: Rosowsky
authors.forename: Carston R
authors.initials: CR
authors.lastname: Wagner
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry; D019008:Drug Resistance, Neoplasm; D005493:Folic Acid Antagonists / Q000138:chemical synthesis* / Q000737:chemistry; D007700:Kinetics; D008727:Methotrexate / Q000737:chemistry*; D009154:Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry* / Q000235:genetics*; D016597:Trimetrexate / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D005493:Folic Acid Antagonists; D011994:Recombinant Proteins; D013762:Tetrahydrofolate Dehydrogenase; D016597:Trimetrexate; D008727:Methotrexate