title: Bcl-2 expression and apoptosis induction in human HL60 leukaemic cells treated with a novel organotellurium(IV) compound RT-04.
abstract: Organotellurium(IV) compounds have been reported to have multiple biological activities including cysteine protease-inhibitory activity, mainly cathepsin B. As cathepsin B is a highly predictive indicator for prognosis and diagnosis of cancer, a possible antitumor potential for these new compounds is expected. In this work, it was investigated the effectiveness of organotellurium(IV) RT-04 to produce lethal effects in the human promyelocytic leukaemia cell line HL60. Using the MTT tetrazolium reduction test, and trypan blue exclusion assay, the IC50 for the compound after 24 h incubation was 6.8 and 0.35 microM, respectively. Moreover, the compound was found to trigger apoptosis in HL60 cells, inducing DNA fragmentation and caspase-3, -6, and -9 activations. The apoptsosis-induced by RT-04 is probably related to the diminished Bcl-2 expression, observed by RT-PCR, in HL60-treated cells. In vivo studies demonstrated that the RT-04 treatment (2.76 mg/kg given for three consecutive days) produces no significant toxic effects for bone marrow and spleen CFU-GM. However, higher doses (5.0 and 10 mg/kg) produced a dose-dependent reduction in the number of CFU-GM of RT-04-treated mice. These results suggest that RT-04 is able to induce apoptosis in HL60 cells by Bcl-2 expression down-modulation. Further studies are necessary to better clarify the effects of this compound on bone marrow normal cells.
authors.affiliation: Universidade de Mogi das Cruzes (UMC), Mogi das Cruzes, São Paulo, Brazil.
authors.forename: T S
authors.initials: TS
authors.lastname: Abondanza
authors.forename: C R
authors.initials: CR
authors.lastname: Oliveira
authors.forename: C M V
authors.initials: CM
authors.lastname: Barbosa
authors.forename: F E G
authors.initials: FE
authors.lastname: Pereira
authors.forename: R L O R
authors.initials: RL
authors.lastname: Cunha
authors.forename: A C F
authors.initials: AC
authors.lastname: Caires
authors.forename: J V
authors.initials: JV
authors.lastname: Comasseto
authors.forename: M L S
authors.initials: ML
authors.lastname: Queiroz
authors.forename: M C
authors.initials: MC
authors.lastname: Valadares
authors.forename: C
authors.initials: C
authors.lastname: Bincoletto
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D019254:Genes, bcl-2 / Q000187:drug effects*; D018922:HL-60 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D008297:Male; D051379:Mice; D009942:Organometallic Compounds / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000970:Antineoplastic Agents; D009942:Organometallic Compounds; C524944:RT-04 compound; D020169:Caspases