title: Analysis of dihydrofolate reductase gene amplification in a methotrexate-resistant human tumor cell line.
abstract: Detailed cytogenetic and molecular biologic studies have been performed on the human KB tumor cell line and four methotrexate-resistant subclones. Results are presented, demonstrating that the gene encoding the target enzyme dihydrofolate reductase is increasingly amplified in progressively methotrexate-resistant subclones, and that dihydrofolate reductase sequences are localized to a homogeneously staining region on chromosome 10q.
mesh_terms: D002460:Cell Line; D002871:Chromosome Banding; D002906:Chromosomes, Human, 6-12 and X; D004351:Drug Resistance; D005111:Extrachromosomal Inheritance; D005784:Gene Amplification; D005796:Genes; D006801:Humans; D008727:Methotrexate / Q000494:pharmacology*; D009693:Nucleic Acid Hybridization; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
chemical_list: D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate