title: The topoisomerase II inhibitor teniposide (VM-26) induces apoptosis in unstimulated mature murine lymphocytes.
abstract: This study shows that not only concanavalin A-stimulated proliferating lymphocytes but also unstimulated mouse splenic lymphocytes are sensitive to the topoisomerase II (topo II) inhibitor teniposide (VM-26). When unstimulated lymphocytes are pretreated with VM-26 for a 2-h period and are then incubated in drug-free medium, cell viability, as determined by trypan blue exclusion, decreases to 40% of the control by 6 h. The drug-treated cultures show two to three times the level of detergent soluble DNA than the control cultures and agarose gel electrophoresis of the soluble DNA shows the presence of oligonucleosomal-sized fragments, a feature considered to be a hallmark of apoptosis. Phase contrast microscopy, Hoechst staining for DNA, and immunofluorescence microscopy of various nuclear and cytoplasmic antigens (nucleolar fibrillarin, snRNP, ubiquitin, vimentin, tubulin) in the VM-26-treated cells characterize the morphological changes during apoptosis of these cells. The role of topo II as the mediator of the VM-26 effects is supported by pulsed field gel electrophoresis, which shows the typical topo II-induced cleavage of supercoiled DNA into loop-sized 300- and 50-kbp fragments. We conclude that the cancer chemotherapeutic agent VM-26 interacts with topo II and induces apoptosis in unstimulated lymphocytes.
authors.affiliation: Department of Biology, University of Ottawa, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Roy
authors.forename: D L
authors.initials: DL
authors.lastname: Brown
authors.forename: J E
authors.initials: JE
authors.lastname: Little
authors.forename: B K
authors.initials: BK
authors.lastname: Valentine
authors.forename: P R
authors.initials: PR
authors.lastname: Walker
authors.forename: M
authors.initials: M
authors.lastname: Sikorska
authors.forename: J
authors.initials: J
authors.lastname: Leblanc
authors.forename: N
authors.initials: N
authors.lastname: Chaly
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D004249:DNA Damage; D004278:DNA, Superhelical / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000166:cytology; D013713:Teniposide / Q000494:pharmacology*; D013997:Time Factors; D059005:Topoisomerase II Inhibitors
chemical_list: D004278:DNA, Superhelical; D059005:Topoisomerase II Inhibitors; D013713:Teniposide