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Ana B Guimaraes-Correa,
Lindsey B Crawford,
Carlos R Figueiredo,
Karina P Gimenes,
Lorena A Pinto,
Maria Fernanda Rios Grassi,
Gerold Feuer,
Luiz R Travassos, Antonio C F Caires,
Elaine G Rodrigues,
Susan J Marriott
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ABSTRACT: Adult T-cell leukemia/lymphoma (ATLL) is a highly aggressive disease that occurs in individuals infected with the human T lymphotropic virus type 1 (HTLV-1). Patients with aggressive ATLL have a poor prognosis because the leukemic cells are resistant to conventional chemotherapy. We have investigated the therapeutic efficacy of a biphosphinic cyclopalladated complex {Pd(2) [S(-)C(2), N-dmpa](2) (μ-dppe)Cl(2)}, termed C7a, in a patient-derived xenograft model of ATLL, and investigated the mechanism of C7a action in HTLV-1-positive and negative transformed T cell lines in vitro. In vivo survival studies in immunocompromised mice inoculated with human RV-ATL cells and intraperitoneally treated with C7a led to significantly increased survival of the treated mice. We investigated the mechanism of C7a activity in vitro and found that it induced mitochondrial release of cytochrome c, caspase activation, nuclear condensation and DNA degradation. These results suggest that C7a triggers apoptotic cell death in both HTLV-1 infected and uninfected human transformed T-cell lines. Significantly, C7a was not cytotoxic to peripheral blood mononuclear cells (PBMC) from healthy donors and HTLV-1-infected individuals. C7a inhibited more than 60% of the ex vivo spontaneous proliferation of PBMC from HTLV-1-infected individuals. These results support a potential therapeutic role for C7a in both ATLL and HTLV-1-negative T-cell lymphomas.
Viruses 07/2011; 3(7):1041-58. · 1.50 Impact Factor
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ABSTRACT: In this minireview, the more recent findings about the effects of peculiar reactive thiol drugs on mitochondria are presented. These include the following compounds: metallo meso-tetrakis porphyrins, palladacycles, telluranes and phenothiazines. Metallo meso-tetrakis porphyrins can exhibit both beneficial and deleterious effects on mitochodria that are modulated by the central metal, cell location, and availability of axial ligands. Therefore, these compounds have the versatility to be used for cell and mitochondria protection and death. The antioxidant activity of manganese porphyrins is related to a glutathione peroxidase-like activity. By attacking exclusively the membrane protein thiol groups without glutathione depletion, palladacycles are able to induce mitochondrial permeability transition (MPT) and cytochrome c release in the absence of oxidative stress. In hepatoma cells, the mitochondrial action of palladacycles was able to induce apoptotic death. As opposed to palladacycles, telluranes and phenothiazines are able to conjugate the capacity to promote the MPT in a dose-dependent manner in association with efficient antioxidant activity toward lipids. These studies demonstrated that the action of drugs on mitochondrial bioenergetics can be modulated by peculiar reactivity with thiol groups. Therefore, they contribute to studies of toxicity as well as the design of new drugs.
Journal of Bioenergetics 01/2011; 43(1):11-8. · 2.81 Impact Factor
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ABSTRACT: Chagas' disease, a neglected tropical infection, affects about 18 million people, and 100 million are at risk. The only drug available, benznidazole, is effective in the acute form and in the early chronic form, but its efficacy and tolerance are inversely related to the age of the patients. Side effects are frequent in elderly patients. The search for new drugs is thus warranted. In the present study we evaluated the in vitro and in vivo effect of a cyclopalladated compound (7a) against Trypanosoma cruzi, the agent of Chagas' disease. The 7a compound inhibits trypomastigote cell invasion, decreases intracellular amastigote proliferation, and is very effective as a trypanocidal drug in vivo, even at very low dosages. It was 340-fold more cytotoxic to parasites than to mammalian cells and was more effective than benznidazole in all in vitro and in vivo experiments. The 7a cyclopalladate complex exerts an apoptosis-like death in T. cruzi trypomastigote forms and causes mitochondrion disruption seen by electron microscopy.
Antimicrobial Agents and Chemotherapy 08/2010; 54(8):3318-25. · 4.84 Impact Factor
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Carlos R Oliveira,
Christiano M V Barbosa,
Fábio D Nascimento,
Camilla S Lanetzki,
Marília B Meneghin,
Flávia E G Pereira,
Edgar J Paredes-Gamero,
Alice T Ferreira,
Tiago Rodrigues,
Mary L S Queiroz, Antonio C F Caires,
Ivarne L S Tersariol,
Claudia Bincoletto
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ABSTRACT: Previous studies reported by our group have introduced a new antitumoural drug called Biphosphinic Palladacycle Complex (BPC). In this paper we show that BPC causes apoptosis in leukaemia cells (HL60 and Jurkat), but not in normal human lymphocytes. IC(50) values obtained for both cell lines using the MTT and trypan blue exclusion assays 5h after BPC treatment were lower than 8.0 microM. Using metachromatic fluorophore, acridine orange, we observed that BPC elicited lysosomal rupture of leukaemic cells. Furthermore, BPC triggered caspase-3 and caspase-6 activation and apoptosis in cell lines, inducing chromatin condensation, apoptotic bodies, and DNA fragmentation. Interestingly, the lysosomal cathepsin B inhibitor CA074 markedly decreased BPC-induced caspase-3 and caspase-6 activation as well as cell death. Lysosomal BPC-induced membrane destabilisation was not dependent on reactive oxygen species generation, which was consistent with the absence of cellular HL60 and Jurkat membrane lipid peroxidation. We conclude that, following BPC treatment, lysosomal membrane rupture precedes cell death and the apoptotic signalling pathway is initiated by the release of cathepsin B in the cytoplasm of leukaemia cells. As no toxic effects for human lymphocytes were observed, we suggest that BPC is more selective for transformed cells, mainly due to their exacerbated lysosome expression.
Chemico-biological interactions 12/2008; 177(3):181-9. · 2.46 Impact Factor
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Christiano M V Barbosa,
Carlos R Oliveira,
Fábio D Nascimento,
Mickaela C M Smith,
Daniela M Fausto,
Marco Antonio Soufen,
Eliana Sena,
Ronaldo C Araújo,
Ivarne L S Tersariol,
Claudia Bincoletto, Antonio C F Caires
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ABSTRACT: The cell death mechanism of cytotoxicity induced by the Biphosphinic Palladacycle Complex (BPC) was studied using a K562 leukaemia cell line. The IC50 values obtained for K562 cells post-72 h of BPC were less than 5.0 microM by using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and trypan blue assays. Using the Acridine Orange vital staining combining fluorescence microscopy it was observed that the complex triggers apoptosis in K562 cells, inducing DNA fragmentation, as analysed through electrophoresis. Lysosomal-membrane permeabilization was also observed in K562 cells post-5 h of BPC, which suggests intralysosomal accumulation by proton-trapping, since its pKa value ranged from 5.1 to 6.5. Caspase-3, and -6 activity induced by BPC in K562 cells was prevented by the cathepsin-B inhibitor [N-(L-3-trans-propylcarbamoyl-oxirane-2-carbonyl)-L-isoleucyl-L-proline] (CA074). These events occurred in the presence of endogenous bcl-2 and bax expression. Acute toxicological studies demonstrated that BPC produces no lesions for liver and kidney fourteen-days after drug administration (100 mg/kg--i.p.). White and red blood cells of BPC-treated mice presented normal morphological characteristics. Taken together, these data suggest a novel lysosomal pathway for BPC-induced apoptosis, in which lysosomes are the primary target and cathepsin B acts as death mediator.
European Journal of Pharmacology 09/2006; 542(1-3):37-47. · 2.52 Impact Factor
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ABSTRACT: Microperoxidases (MP) as water-soluble models attract interest to studying the reaction mechanism of peroxidases because these heme peptides are able to form the same enzyme intermediates during the reaction with peroxides. In this work we have demonstrated that the association of Fe(III)MP-9 and Fe(III)MP-11 with CTAB micelles (MP-9/CTAB and MP11/CTAB) provides a microenvironment with an alkaline interface and a hydrophobic core that exhibits peroxidase behavior. This microenvironment shifts positively the redox potential of microperoxidases by approximately 100 mV. tert-Butylhydroperoxide (t-BuOOH) when added to the medium, converted Fe(III)MP-9/CTAB to MP-9/CTAB Compound II, a high valence oxidized intermediate of the heme peptide. Subsequent addition of diphenylacetaldehyde (DPAA) to MP-9/CTAB Compound II regenerated the native form of the enzyme, Fe(III)MP-9/CTAB, what characterizes the occurrence of a peroxidase cycle. Fe(III)MP-9/CTAB regenerated during the peroxidase cycle reacted with residual DPAA in the medium to form Fe(II)MP-9/CTAB, which indicates that both Fe(III)MP-9/CTAB and its oxyferryl form can use aldehydes as reducing agents. According to the determined reduction potential, Fe(III)MP-9 and Fe(III)MP-9/CTAB should be able to oxidize DPAA (reduction potential -630 mV). The reaction of MP-9/CTAB with DPAA produced benzophenone as final product, detected by infrared spectroscopy and mass spectrometry. Interestingly, a significant difference was observed in the benzophenone yield according to the micelle/MP-9 molar ratio.
Physical Chemistry Chemical Physics 05/2006; 8(16):1963-73. · 3.57 Impact Factor
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ABSTRACT: Chiral cyclopalladated complexes derived from N,N-dimethyl-1-phenethylamine and the coordinating ligand 1,1'-bis(diphenylphosphine)ferrocene were synthesized and studied as Cathepsin B inhibitors and antitumoral agents against solid tumors. Our results revealed that the palladium compound [Pd2(C2,N-S(-)dmpa)2(mu-dppf)Cl2] (2) was able to inhibit Cathepsin B activity in a reversible fashion. This palladacycle compound binds to free cathepsin B (E) as well as to the enzyme-substrate complex (ES) with dissociation constants of KH=12+/-1 microM and alphaKH=2.4+/-0.3 microM, respectively. The application of this complex, in Walker tumor-bearing rats, resulted in 90% inhibition of the tumor growth. Subcutaneous inoculations of 10(6) tumoral cells produced solid tumors with a mass of 4.0+/-1.0 g in 12 days Walker tumor-bearing rats. However, when these animals were treated with one dose of the palladacycle compound (2.0 mg/kg), the tumoral mass was reduced to 0.3+/-0.1 g. On the other hand, the same complex (2) did not afford any protection to mice bearing the non-metastatic Ehrlich Ascites tumor treated with doses of 0.5, 5.0, and 30 mg/kg for a period of four, three and one day, respectively, beginning 72 h after tumor inoculation. Toxicological studies using mice treated with one high dose of the complex (2) (100 mg/kg) did not show any alterations in red and white blood cell morphology 14 days after the drug administration. Similar results were obtained with hepatic, kidney, and spleen tissues. The results presented in this work introduce the title cyclopalladated complexes as promising antitumoral drugs with reduced toxicity in experimental studies.
Bioorganic & Medicinal Chemistry 05/2005; 13(8):3047-55. · 2.92 Impact Factor
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ABSTRACT: In the present study, we introduce a new class of organometallic compound, the Biphosphinic Palladacycle Complex [Pd (C2, N-S(-)(dmpa)(dppf)] Cl (BPC), as an angiotensin-I converting-enzyme inhibitor (ACEI) with hematological regulation properties. When BPC was assayed as a competitive inhibitor over the hydrolysis of Abz-YRK (Dnp)-P-OH (Km = 7.0 microM), it showed a Kiapp = 0.2259 ng and a Ki value of 94.12 pg. Using murine long-term bone marrow cultures (LTBMCs) and clonal culture techniques, we also evaluated the capacity of this drug (1.18 microM) to module haematopoietic progenitor cells proliferation in vitro and in vivo. Our results demonstrated that BPC produces no toxicity to bone marrow cells, as determined by the unchanged cell number in the non-adherent layer at weeks 1, 2, and 8 and the increased number of adherent cells present in the BPC-treated LTBMCs. However, the proportion of CFU-Cs in the non-adherent cell layer was reduced at weeks 5, 6, 8, and 9. In vivo studies using the dose of 1 mg/kg of BPC, administered by subcutaneous route, presented similar result as those found in vitro, in the number of CFU-Cs. This latter finding may be explained by the inhibitory effects of this drug on the ACE activity, which probably result in increased levels of its substrate AcSDKP, a negative regulator of hematopoiesis.
Immunopharmacology and Immunotoxicology 02/2004; 26(4):487-500. · 1.83 Impact Factor
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ABSTRACT: Palladacycle compounds obtained from N, N-dimethyl-1-phenethylamine (dmpa), phenyl-2-pyridinyl-acetylene and 1-phenyl-3-N, N-dimethylamine-propine, respectively, were complexed to 1, 2 ethanebis (diphenylphosphine) (dppe) ligand to synthesize antitumor cyclopalladated complexes that were tested in vitro and in vivo against syngeneic B16F10-Nex2 murine melanoma cells of low immunogenicity implanted subcutaneously in mice. Complexes were not toxic to mice injected 3 times i.p. with as much as 60 microM/animal/week. Of 3 cyclopalladated complexes that were inhibitory in vitro at low concentrations (<1.25 microM), complex 7a was the most active in vivo, delaying tumor growth and prolonging animal survival. In vitro, binucleate complex 7a caused a collapse of respiratory activity with an abrupt decrease of extracellular acidification on short incubation (up to 100 min), followed by DNA degradation after 24 hr. The apoptosis-like reaction to this Pd-complex was not accompanied by increased levels of caspases 1 and 3. Complex 7a bound to a bacterial plasmid DNA, causing late conformational changes after 24 hr. Two other complexes with different C, N-cycles were also apoptotic and 2 binucleated ones were inactive. These results introduce the palladacycle-dppe complexes as promising antitumor drugs with exquisite structural specificities and for action in vivo and in vitro.
International Journal of Cancer 12/2003; 107(3):498-504. · 5.44 Impact Factor
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Christiano M.V. Barbosa,
Carlos R. Oliveira,
Fábio D. Nascimento,
Mickaela C.M. Smith,
Daniela M. Fausto,
Marco Antonio Soufen,
Eliana Sena,
Ronaldo C. Araújo,
Ivarne L.S. Tersariol,
Claudia Bincoletto, Antonio C.F. Caires
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ABSTRACT: The cell death mechanism of cytotoxicity induced by the Biphosphinic Palladacycle Complex (BPC) was studied using a K562 leukaemia cell line. The IC50 values obtained for K562 cells post-72 h of BPC were less than 5.0 μM by using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and trypan blue assays. Using the Acridine Orange vital staining combining fluorescence microscopy it was observed that the complex triggers apoptosis in K562 cells, inducing DNA fragmentation, as analysed through electrophoresis. Lysosomal-membrane permeabilization was also observed in K562 cells post-5 h of BPC, which suggests intralysossomal accumulation by proton-trapping, since its pKa value ranged from 5.1 to 6.5. Caspase-3, and -6 activity induced by BPC in K562 cells was prevented by the cathepsin-B inhibitor [N-(l-3-trans-propylcarbamoyl-oxirane-2-carbonyl)-l-isoleucyl-l-proline] (CA074). These events occurred in the presence of endogenous bcl-2 and bax expression. Acute toxicological studies demonstrated that BPC produces no lesions for liver and kidney fourteen-days after drug administration (100 mg/kg — i.p.). White and red blood cells of BPC-treated mice presented normal morphological characteristics. Taken together, these data suggest a novel lysosomal pathway for BPC-induced apoptosis, in which lysosomes are the primary target and cathepsin B acts as death mediator.
European Journal of Pharmacology.
