title: Differential expression of human topoisomerase IIIalpha during the cell cycle progression in HL-60 leukemia cells and human peripheral blood lymphocytes.
abstract: Human topoisomerase IIIalpha (huTop IIIalpha) has been demonstrated to belong to type IA subfamily. In this study, we found that huTop IIIalpha expressed constitutively and remained at high levels throughout the cell cycle in HL-60 cells when compared to the cell-cycle-dependent expression of huTop IIIalpha in phytohemagglutinin-activated peripheral blood lymphocytes. During the cell cycle progression, this protein remained accentuated in the nucleolus without significant translocation from the nucleolus to the nucleoplasm. In addition, during the course of granulocytic maturation in DMSO-treated HL-60 cells, huTop IIIalpha levels decreased when cells stopped proliferation and nucleoli diminished in size. However, its level remained unchanged during the course of monocytic maturation of vitamin D(3)-treated HL-60 cells which still retained its proliferative capacity and did not change the size of the nucleolus. The data suggested that huTop IIIalpha is involved in rDNA metabolism, such as rDNA transcription. Its cellular level appeared to be under control during the cell cycle progression of normal lymphocytes, but was found to be deregulated in HL-60 cells which may be associated with the tumor transformed cell phenotypes.
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Lin
authors.forename: Z
authors.initials: Z
authors.lastname: Darzynkiewicz
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: F
authors.initials: F
authors.lastname: Traganos
authors.forename: E
authors.initials: E
authors.lastname: Bedner
authors.forename: Y C
authors.initials: YC
authors.lastname: Tse-Dinh
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies; D002453:Cell Cycle / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D002466:Cell Nucleolus / Q000201:enzymology; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004264:DNA Topoisomerases, Type I / Q000032:analysis / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D006098:Granulocytes / Q000201:enzymology; D018922:HL-60 Cells; D006801:Humans; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000166:cytology* / Q000201:enzymology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D010782:Photolysis
chemical_list: D000906:Antibodies; D010446:Peptide Fragments; D004264:DNA Topoisomerases, Type I; D004121:Dimethyl Sulfoxide