Overproduction of dihydrofolate reductase and gene amplification in methotrexate-resistant Chinese hamster ovary cells

Journal Article · Mon Mar 01 04:00:00 EST 1982 · Mol. Cell. Biol.; (United States)

DOI:https://doi.org/10.1128/MCB.2.3.275· OSTI ID:5606792

Flintoff, W F; Weber, M K; Nagainis, C R; Essani, A K; Robertson, D; Salser, W

Stable isolates of Chinese hamster ovary cells that are highly resistant to methotrexate have been selected in a multistep selection process. Quantitative immunoprecipitations have indicated that these isolates synthesize dihydrofolate reductase at an elevated rate over its synthesis in sensitive cells. Restriction enzyme and Southern blot analyses with a murine reductase cDNA probe indicate that the highly resistant isolates contain amplifications of the dihydrofolate reductase gene number. Depending upon the parental line used to select these resistant cells, they overproduce either a wild-type enzyme or a structurally altered enzyme. Karyotype analysis shows that some of these isolates contain chromosomes with homogeneously staining regions whereas others do not contain such chromosomes.

• Research Organization: Dept. of Microbiology and Immunology, Univ. of Western Ontario, London, Ontario N6A 5C1
• OSTI ID: 5606792
• Journal Information: Mol. Cell. Biol.; (United States), Journal Name: Mol. Cell. Biol.; (United States) Vol. 2:3; ISSN MCEBD
• Country of Publication: United States
• Language: English

Related Subjects

550400* -- Genetics
560300 -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANTIMETABOLITES
BIOLOGICAL EFFECTS
CELL CULTURES
CELL TRANSFORMATIONS
CHO CELLS
CHROMOSOMES
DNA
DRUGS
ELECTROPHORESIS
ENZYME INHIBITORS
ENZYMES
GENE AMPLIFICATION
IMMUNOLOGY
KARYOTYPE
METHOTREXATE
NUCLEIC ACIDS
NUCLEOTIDE DEHYDROGENASES
ONCOGENIC TRANSFORMATIONS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PRECIPITATION
SENSITIVITY
SEPARATION PROCESSES