6533b832fe1ef96bd129a5c0
RESEARCH PRODUCT
Nalidixic acid-resistant V79 cells with reduced DNA topoisomerase II activity and amplification prone phenotype
Aldo Di LeonardoP. CavolinaAdriana Maddalenasubject
Nalidixic acidCell SurvivalHealth Toxicology and MutagenesisDrug ResistanceAntineoplastic AgentsBiologyCell LineNalidixic Acidchemistry.chemical_compoundCricetulusCricetinaeGeneticsmedicineAnimalsTopoisomerase II InhibitorsMolecular BiologyGeneEtoposideEtoposideCell NucleusMesocricetusTopoisomeraseGene AmplificationNucleic Acid HybridizationDNADNA topoisomerase II activityMolecular biologyDNA Topoisomerases Type IIPhenotypeDNA Topoisomerases Type IchemistryDoxorubicinbiology.proteinTopoisomerase-II InhibitorSister Chromatid ExchangeDNACamptothecinmedicine.drugdescription
Spontaneously nalidixic acid-resistant lines (NAr lines) were selected from a V79 Chinese hamster cell line and phenotypically characterized. NAr lines showed an increased doubling time, a higher number of spontaneous SCE, and more interestingly, decreased DNA topoisomerase II activity. These lines were also cross-resistant to the eukaryotic topoisomerase II inhibitors etoposide and adriamycin, but showed the same level of sensitivity as the parental line to the DNA topoisomerase I inhibitor camptothecin. NAr lines were cross-resistant to other drugs, such as PALA, MTX and MPA, resistance to which has been shown to arise by amplification of the target genes. This last feature, together with enhanced cross-resistance to PALA and MTX when employed simultaneously, suggests that NAr lines have an 'amplification prone' phenotype. From these results the decreased activity of topoisomerase II seems to be involved in the generation of amplified sequences possibly by affecting recombinational events underlying gene amplification.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1992-10-01 | Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis |