title: Drug resistance to DNA topoisomerase I and II inhibitors in human leukemia, lymphoma, and multiple myeloma.
abstract: Several antineoplastic agents used in the treatment of hematologic malignancies exert their cytotoxic effects by inhibiting the activity of nuclear DNA topoisomerase (topo) I or II. Mechanisms of drug resistance to topoisomerase inhibitors have been defined at the molecular level from in vitro studies using model cell lines, and include quantitative and qualitative changes in topo I and II. The possible roles of these mechanisms in clinical drug resistance and clinical outcomes for patients with hematologic malignancies are now under investigation. Available data indicate that the blast content of topo II does not correlate with clinical outcome in acute myeloid leukemia (AML), and this may also be true in acute lymphocytic leukemia (ALL). Chronic lymphocytic leukemia (CLL) cells are resistant to topo II inhibitors because they express low levels of topo II. Further studies using sequential biopsy samples and assays of topoisomerase activity should establish the role that changes in topo I and II activity play in the development of drug resistance in hematologic malignancies.
authors.affiliation: Department of Internal Medicine, H. Lee Moffitt Cancer Center & Research Institute, University of South Florida, Tampa, USA.
authors.forename: N I
authors.initials: NI
authors.lastname: Valkov
authors.forename: D M
authors.initials: DM
authors.lastname: Sullivan
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D004264:DNA Topoisomerases, Type I / Q000235:genetics; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D006801:Humans; D007938:Leukemia / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D008223:Lymphoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II