Molecular cloning and identification of a point mutation in the topoisomerase II cDNA from an etoposide-resistant Chinese hamster ovary cell line.

摘要: Abstract Topoisomerase II (Top II) is the target enzyme for many antineoplastic drugs such as epipodophyllotoxins, anthracyclines, and acridines. Cell lines with alterations in Top are resistant to that interact enzyme. Studies of from a Chinese hamster ovary line, VpmR-5, VP-16 VM-26, demonstrated it very similar, qualitatively quantitatively, its normal counterpart except DNA cleavage by VpmR-5 not stimulated or VM-26. To understand basis drug-resistant phenotype, cDNAs were isolated both (CHO) cells cDNA cloning lambda gt22, entire sequenced. A mutation G-->A at nucleotide 1478 was only alteration observed compared wild-type gene. The confirmed sequencing fragments amplified genomic polymerase chain reaction. Southern blot hybridization analysis loss allele probably occurred during development resistance etoposide. changes amino acid 493 arginine glutamine located adjacent putative ATP binding site II. Mutations an analogous region have been identified two human leukemia cell amplification segments Taq polymerase. Taken together, these observations suggest mutations this gyrase B domain mammalian topoisomerase may be capable conferring agents