title: Topoisomerase II alpha and beta in human tumor cells grown in vitro and in vivo.
abstract: The cellular content and the cell-cycle distribution of the 170 kD- and 180 kD-isoforms of DNA topoisomerase II were investigated in human tumor cells with specific monoclonal antibodies and by immunofluorescent detection with flow cytometry. Levels of topo II alpha were almost three-fold higher than the beta-isozyme in exponentially growing cells in vitro. In contrast, topo II alpha but not beta, was markedly reduced in plateau-phase cells. Tumor cells from surgical biopsies, mainly in G0/G1 phase, exhibited a 95% beta- versus 5% alpha-isoform expression. These results support the hypothesis that topo II alpha is mainly related to DNA synthesis, and topo II beta to DNA transcription.
authors.affiliation: Centro di Studio per l'Istochimica del C.N.R., Dipartimento di Biologia Animale, Università di Pavia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Prosperi
authors.forename: E
authors.initials: E
authors.lastname: Sala
authors.forename: C
authors.initials: C
authors.lastname: Negri
authors.forename: C
authors.initials: C
authors.lastname: Oliani
authors.forename: R
authors.initials: R
authors.lastname: Supino
authors.forename: G B
authors.initials: GB
authors.lastname: Astraldi Ricotti
authors.forename: G
authors.initials: G
authors.lastname: Bottiroli
mesh_terms: D000911:Antibodies, Monoclonal; D018288:Carcinoma, Small Cell / Q000201:enzymology; D015179:Colorectal Neoplasms / Q000201:enzymology; D004250:DNA Topoisomerases, Type II / Q000032:analysis / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006652:Histological Techniques; D006801:Humans; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism*; D007890:Leiomyosarcoma / Q000201:enzymology; D008175:Lung Neoplasms / Q000201:enzymology; D008545:Melanoma / Q000201:enzymology; D009369:Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000601:surgery; D010051:Ovarian Neoplasms / Q000201:enzymology; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000201:enzymology
chemical_list: D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D004250:DNA Topoisomerases, Type II