title: DNA topoisomerase I as a site of action for 10-hydroxycamptothecin in human promyelocytic leukemia cells.
abstract: We investigated the antiproliferative effect of 10-hydroxycamptothecin (HCPT), an alkaloid isolated from Camptotheca acuminata, on the human promyelocytic leukemia cell line, HL-60, and a 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA)-resistant mutant, HL-60/m-AMSA. Using trypan blue dye exclusion and colony formation, doses of HCPT ranging from 0.01 to 1 microM progressively inhibited growth in both cell lines in a concentration-dependent manner. A minimal cross-resistance, approximately five-fold, between the wild-type and resistant cells was observed. Using the technique of alkaline elution, HCPT produced DNA single-strand breaks and protein-associated DNA strand cleavage in HL-60 and HL-60/m-AMSA cells. Quantitative analysis of drug-induced protein-DNA complexes was performed using sodium dodecyl sulfate-potassium chloride precipitation. In both cell lines, a good correlation with HCPT-induced cytotoxicity was observed. Similar results were achieved in wild-type cells treated with m-AMSA. Enzyme activity was measured in nuclei isolated from HL-60 and HL-60/m-AMSA cells, and in each case HCPT inhibited topoisomerase I activity to the same extent. The data suggest that the principle mechanisms for HCPT-induced cytotoxicity in HL-60 and HL-60/m-AMSA cells are inhibition of DNA topoisomerase I and production of protein-associated DNA strand breaks.
authors.affiliation: Department of Experimental Pediatrics, University of Texas M. D. Anderson Cancer Center, Houston 77030.
authors.forename: Y H
authors.initials: YH
authors.lastname: Ling
authors.forename: B S
authors.initials: BS
authors.lastname: Andersson
authors.forename: J A
authors.initials: JA
authors.lastname: Nelson
mesh_terms: D000677:Amsacrine / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D004249:DNA Damage; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004351:Drug Resistance; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology; D009154:Mutation; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured / Q000201:enzymology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D000677:Amsacrine; D005047:Etoposide; C028098:10-hydroxycamptothecin; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D002166:Camptothecin