title: Effect of DNA topoisomerase I inhibitor, 10-hydroxycamptothecin, on the structure and function of nuclei and nuclear matrix in bladder carcinoma MBT-2 cells.
abstract: The effects of 10-hydroxycamptothecin (HCPT), a DNA topoisomerase I inhibitor, on the structure of nuclei and nuclear matrix and new DNA replication was investigated in murine bladder carcinoma MBT-2 cells. Following 10-30 min exposure of exponentially growing cells to 10-50 microM HCPT, the rate of 2 min pulse-labeling with [3H]thymidine in whole nuclei, nonmatrix, and matrix fractions was markedly decreased in a concentration- and time-dependent manner. Reduction was highest in the nuclear matrix. After treatment of cultures with 50 microM HCPT for 10 min, inhibition of DNA synthesis was 60% in the nuclear matrix and 27% in the low-salt extract fraction tended to be stimulated after drug treatment. SDS-PAGE analysis of [35S]methionine labeled proteins indicated that 50 microM HCPT decreased protein synthesis in the matrix and other nuclear subfractions. HCPT-induced ultrastructural changes in nuclei and nuclear matrix were similar to those typically associated with lesions of DNA replication or RNA transcription.
authors.affiliation: Department of Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
authors.forename: Y H
authors.initials: YH
authors.lastname: Ling
authors.forename: R
authors.initials: R
authors.lastname: Perez-Soler
authors.forename: M T
authors.initials: MT
authors.lastname: Tseng
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002467:Cell Nucleus / Q000187:drug effects* / Q000648:ultrastructure; D004261:DNA Replication / Q000187:drug effects*; D004273:DNA, Neoplasm / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D015530:Nuclear Matrix / Q000187:drug effects; D009687:Nuclear Proteins / Q000032:analysis / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000648:ultrastructure*
chemical_list: D034961:Antigens, Nuclear; D000972:Antineoplastic Agents, Phytogenic; D004273:DNA, Neoplasm; D009687:Nuclear Proteins; C028098:10-hydroxycamptothecin; D002166:Camptothecin