title: Reduced topoisomerase II-mediated DNA cleavage in VP-16 resistant human leukemic cell line.
abstract: Drug resistance in the VP-16 resistant human leukemic cell line (THP-1/E) was studied the possible relevance of topoisomerase II activity. Strand-passing activity in crude nuclear extract from sensitive and resistant cells was comparable and equally sensitive to inhibition by VP-16. However, it was demonstrated that VP-16-mediated pBR322 DNA cleavage in the presence of nuclear extract from resistant cells was reduced to one-tenth of that from sensitive cells. These results suggested that the resistance of THP-1/E cells to VP-16 was due to reduced DNA cleavage activity.
authors.affiliation: Department of Internal Medicine, Tohoku University, Sendai, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Saijo
authors.forename: K
authors.initials: K
authors.lastname: Satoh
authors.forename: Y
authors.initials: Y
authors.lastname: Tokue
authors.forename: N
authors.initials: N
authors.lastname: Kumano
authors.forename: M
authors.initials: M
authors.lastname: Motomiya
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004351:Drug Resistance / Q000502:physiology*; D005047:Etoposide / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D007938:Leukemia; D010957:Plasmids
chemical_list: D005047:Etoposide; D004250:DNA Topoisomerases, Type II