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ABSTRACT: PurposeMicrotubule-stabilizing agents are an important class of anticancer compounds. Peloruside A and laulimalide bind to a different
site on the microtubule to taxoid site drugs such as paclitaxel (Taxol®), docetaxel (Taxotere®), ixabepilone (Ixempra®), the epothilones, and discodermolide. The purpose of this study was to examine the synergistic interactions of these drugs
when given in combination in relation to the differences in their binding sites on the microtubule.
MethodsHuman ovarian carcinoma cells (1A9 cells) and murine T cells were treated with different combinations of microtubule-stabilizing
or destabilizing agents. The compounds were given individually and in combination, and the antiproliferative activity was
assessed to calculate a combination index (CI) from the equation: CI=D
1/Dx
1+D
2/Dx
2 in which D
1 and D
2 are the concentrations of drug 1 and drug 2 that when given together give the same response as drug 1 and 2 alone (Dx
1 and Dx
2). Thus, a CI value of less than 1.0 indicates a synergistic effect between the two drugs in which the response to the two
drugs given together is greater than the additive response of the two drugs if given on their own.
ResultsAs anticipated from previous invitro studies, peloruside A and laulimalide did not synergize with each other. They also failed
to synergize with the microtubule-destabilizing agents vinblastine and 2-methoxyestradiol. Peloruside A and laulimalide did,
however, synergize with the epothilones, as had been previously shown, but not with docetaxel or discodermolide.
ConclusionsCombining two microtubule-targeting agents with different binding sites does not guarantee a synergistic interaction in cells,
and additional factors are likely to be involved. This study highlights the importance of preclinical testing of actual combinations
of drugs before proceeding into clinical trials.
KeywordsAnticancer drug–Combination therapy–Laulimalide–Microtubule-targeting agent–Peloruside A–Synergy
Cancer Chemotherapy and Pharmacology 04/2012; 68(1):117-126. · 2.83 Impact Factor
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ABSTRACT: Chronic Schistosoma mansoni infection can present as a moderate or severe disease, termed intestinal or hepatosplenic schistosomiasis, respectively. Similarly, either moderate splenomegaly or hypersplenomegaly syndrome develops in CBA/J mice by 20weeks of infection and is similar to intestinal or hepatosplenic schistosomiasis respectively. Using this mouse model and two-dimensional differential in gel electrophoresis, the liver proteomic signatures of uninfected mice and mice infected for 6, 8, 12, or 20weeks were compared, and significant protein spots identified using mass spectrometry. We found the greatest number of changes at 12weeks suggesting that this period represents the peak time of change. Pathway analysis identified specific proteins and pathways that correlated to the pathological changes indicative of severe disease, and these pathways were involved as early as 8weeks after infection. These findings provide insight into the development of severe liver pathology in schistosomiasis and may aid in developing biomarkers for hepatosplenic schistosomiasis.
Journal of proteomics 03/2012; 75(6):1838-48. · 5.07 Impact Factor
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ABSTRACT: Microtubule-stabilizing agents are an important class of anticancer compounds. Peloruside A and laulimalide bind to a different site on the microtubule to taxoid site drugs such as paclitaxel (Taxol(®)), docetaxel (Taxotere(®)), ixabepilone (Ixempra(®)), the epothilones, and discodermolide. The purpose of this study was to examine the synergistic interactions of these drugs when given in combination in relation to the differences in their binding sites on the microtubule.
Human ovarian carcinoma cells (1A9 cells) and murine T cells were treated with different combinations of microtubule-stabilizing or destabilizing agents. The compounds were given individually and in combination, and the antiproliferative activity was assessed to calculate a combination index (CI) from the equation: CI = D(1)/Dx(1) + D(2)/Dx(2) in which D(1) and D(2) are the concentrations of drug 1 and drug 2 that when given together give the same response as drug 1 and 2 alone (Dx(1) and Dx(2)). Thus, a CI value of less than 1.0 indicates a synergistic effect between the two drugs in which the response to the two drugs given together is greater than the additive response of the two drugs if given on their own.
As anticipated from previous in vitro studies, peloruside A and laulimalide did not synergize with each other. They also failed to synergize with the microtubule-destabilizing agents vinblastine and 2-methoxyestradiol. Peloruside A and laulimalide did, however, synergize with the epothilones, as had been previously shown, but not with docetaxel or discodermolide.
Combining two microtubule-targeting agents with different binding sites does not guarantee a synergistic interaction in cells, and additional factors are likely to be involved. This study highlights the importance of preclinical testing of actual combinations of drugs before proceeding into clinical trials.
Cancer Chemotherapy and Pharmacology 07/2011; 68(1):117-26. · 2.83 Impact Factor
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ABSTRACT: Previously, we demonstrated unique protein expression patterns in 20-week-Schistosoma mansoni-infected CBA/J mice with moderate splenomegaly syndrome (MSS) or hypersplemomegaly syndrome (HSS). To better understand the development of severe pathology, we compared the two-dimensional differential in-gel electrophoresis (2D-DIGE) proteomic signatures of livers from uninfected mice and mice infected for 6, 8, 12, or 20 weeks and found significant changes in collagen isoforms, interleukin-2 (IL-2), cytokeratin 18, hydroxyproline, S. mansoni phosphoenolpyruvate carboxykinase, major urinary protein isoforms, and peroxiredoxin 6. Cytokeratin 18, hydroxyproline, and connective tissue growth factor (CTGF) were chosen for analysis in mouse and human sera using targeted biochemical assays. Consistent with the liver analysis, cytokeratin 18, CTGF, and hydroxyproline were significantly elevated in sera from mice with HSS compared to those from uninfected mice or mice with MSS. Moreover, cytokeratin 18 and CTGF were found to be markers for subjects with hepatosplenic and intestinal schistosomiasis, respectively, while serum hydroxyproline was a strong indicator of fibrosis for severe HS. These findings indicate that schistosome-associated changes to the liver can be detected in the serum and reveal the potential for cytokeratin 18 to be used as a diagnostic marker for early detection of hepatosplenic schistosomiasis.
Infection and immunity 02/2011; 79(5):2051-8. · 4.21 Impact Factor
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ABSTRACT: To kill antigen-specific target cells (TCs), cytotoxic T lymphocytes (CTLs) reorganise their microtubule cytoskeleton to deliver lytic granules to the TCs. We used two drugs that stabilise microtubules, paclitaxel and peloruside, to determine how the stabilising microtubule network affects CTL function in vitro and in vivo. In vitro, neither paclitaxel nor peloruside inhibited antigen-specific killing, lytic granule delivery to the cell surface, nor interferon-gamma release by murine CTLs. In contrast, in an in vivo murine model of antigen-induced killing, a single dose of paclitaxel had a significant inhibitory effect on killing by CTLs. Furthermore, the inhibitory effect of paclitaxel was not caused by specific deletion of the effector CTL population in drug-treated mice. The findings reveal that microtubule-stabilising drug treatment can lead to immediate impairment of CTL function without affecting lytic granule release. The results also suggest that patients undergoing taxane anti-cancer therapy may be impaired in their ability to fight infection before the anti-mitotic effects of paclitaxel are apparent.
Immunology and Cell Biology 12/2009; 88(3):291-6. · 3.66 Impact Factor
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ABSTRACT: Treatment with immune complexes, which ligate Fcgamma receptors (FcgammaRs), suppresses the development of experimental autoimmune encephalomyelitis (EAE). To determine the mechanism of action, we investigated how these immune complexes affected type II activation of macrophages (that is, exposure to immune complexes in a proinflammatory environment). Our results show that lower doses of interferon-gamma (IFN-gamma) were more effective at priming bone marrow-derived macrophages (BMMphi) to produce more interleukin 10 (IL-10) and less IL-12p40 in response to lipopolysaccharide (LPS) and immune complexes compared with LPS alone. Moreover, at the lowest level of IFN-gamma (20 U ml(-1)), a significant downregulation in the surface expression of CD40, CD80 and PD-L1 was observed in LPS and immune complex-stimulated macrophages (that is, type II activated) than macrophages stimulated with LPS alone (that is, classically activated). Finally, treatment of mice with type II-activated macrophages protected them from developing EAE, suggesting that administration of immune complexes is protective against EAE by inducing type II-activated macrophages.
Immunology and Cell Biology 01/2009; 87(3):235-40. · 3.66 Impact Factor
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ABSTRACT: The arrival of eggs in the liver during Schistosoma mansoni infection initiates a protective granulomatous response; however, as the infection progresses, this response results in chronic liver fibrosis. To better understand the impact of schistosomiasis on liver function, we used a proteomic approach to identify proteins whose expression was significantly altered in schistosome-infected mice 8 weeks postinfection. Identification of differentially expressed proteins by mass fingerprinting revealed that schistosome infection markedly reduced the abundance of proteins associated with several normal liver functions (i.e., citric acid cycle, fatty acid cycle, and urea cycle), while proteins associated with stress responses, acute phase reactants, and structural components were all significantly more abundant. The expression patterns of several immunity-related proteins (peroxiredoxin 1, arginase 1, and galectin 1) suggested that different protein forms are associated with schistosome infection. These findings indicate that acute schistosomiasis has a significant impact on specific liver functions and, moreover, that the alterations in specific protein isoforms and upregulation of unique proteins may be valuable as new markers of disease.
Infection and Immunity 03/2007; 75(2):736-44. · 4.16 Impact Factor
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ABSTRACT: Experimental autoimmune encephalomyelitis (EAE) is an organ-specific autoimmune disease model used to investigate mechanisms involved in the activation of self-reactive T cells. Preproenkephalin (PPNK) is the gene that encodes the protein proenkephalin A that has been detected in the brain, adrenal cells and cells of the immune system. In this paper, whether PPNK plays a role in the development of EAE was investigated. PPNK-deficient and wild-type mice were immunized with the MOG(35-55) peptide and the development of EAE observed. Our results show that PPNK-deficient mice developed less severe clinical signs of disease than wild-type mice, and with lower incidence. MOG(35-55)-specific T cells from PPNK-deficient and wild-type mice produced IFNgamma and TNFalpha but no IL-4 or IL-10, indicative of a Th1 phenotype. However, the numbers of MOG(35-55)-specific IFNgamma-producing cells from immunized PPNK-deficient mice were largely reduced at early stages of disease. Interestingly, there was no difference in clinical signs or infiltrating mononuclear cells in the CNS between wild-type and PPNK-deficient mice at the later stage of disease. Our results suggest that PPNK accelerates the generation of autoimmune IFNgamma-producing T cells and MOG(35-55)-induced EAE.
Journal of Neuroimmunology 11/2006; 179(1-2):18-25. · 2.96 Impact Factor
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ABSTRACT: The incidences of schistosomiasis and multiple sclerosis (MS) are mutually exclusive worldwide suggesting that schistosomiasis may offer protection against the induction of the immune-mediated disease, MS. Recent studies using the mouse model of MS, experimental autoimmune encephalomyelitis, support a direct suppression of the onset of MS by chronic Schistosoma mansoni infection. Self-reactive Th1 but not Th2 responses develop in infected mice immunized with myelin oligodendrocyte glycoprotein albeit at reduced levels indicating that the induction of auto-reactive T cells is not abolished nor phenotypically altered. CNS infiltration by inflammatory cells, particularly macrophages, is significantly reduced in S. mansoni-infected, immunized mice compared to uninfected, immunized mice. Because activated macrophages are crucial to the induction of clinical disease, these findings support the hypothesis that differences in macrophage activation may contribute to the reduced incidence and delayed progression of experimental autoimmune encephalomyelitis during schistosomiasis.
Memórias do Instituto Oswaldo Cruz 02/2004; 99(5 Suppl 1):33-6. · 2.15 Impact Factor
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ABSTRACT: A preestablished infection with the parasitic helminth, Schistosoma mansoni, significantly reduced the incidence and delayed the onset of experimental autoimmune encephalomyelitis (EAE) in C57BL/6J mice immunized with myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide. The altered disease progression was not solely due to the induction of a strong Th2 response, since intraperitoneal injection of schistosome eggs did not affect disease development. MOG-specific gamma interferon (IFN-gamma), nitric oxide, and tumor necrosis factor alpha production by splenocytes was significantly reduced in schistosome-infected mice compared to uninfected mice. However, similar levels of interleukin-10 (IL-10) were produced in an antigen-specific manner, suggesting that the induction of antigen-specific responses was not inhibited. Analysis of in vivo cytokine production by real-time PCR indicated that IL-12p40, but not IFN-gamma, transcript levels were dramatically reduced in the spinal cords of schistosome-infected, MOG-immunized mice. Furthermore, analysis of the cellular composition of the spinal cords and brains revealed that a preestablished infection with S. mansoni decreased central nervous system (CNS) inflammation, particularly of macrophages and CD4 T cells. These results suggest that schistosomiasis may negatively regulate the onset of EAE by downregulating the production of proinflammatory cytokines and altering CNS inflammation.
Infection and Immunity 10/2003; 71(9):4996-5004. · 4.16 Impact Factor
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ABSTRACT: The role of the third component of complement (C3) during schistosome infection was investigated using mice deficient in C3. While no effect was observed 8 wk after infection on worm development or liver pathology, Ag-specific Th2-associated cytokine production (IL-13, IL-5, IL-6, and IL-10) was significantly reduced, and IFN-gamma production was enhanced in the absence of C3. IgG1 and IgE, but not IgG2a or IgM, Ab responses were also significantly impaired in infected C3(-/-) mice, suggesting that C3 may play a role in IL-4-mediated Th2 response enhancement during schistosome infection. Furthermore, C3-deficient mice could not effectively clear adult worms after praziquantel (PZQ) treatment and suffered increased morbidity due to the overproduction of proinflammatory mediators following drug administration. However, the ischemic liver damage that normally accompanies PZQ administration in infected wild-type mice was substantially reduced in treated C3-deficient mice, probably due to the absence of dead or dying worms in the livers of these animals. Together these results indicate that C3 enhances Th2 responses during schistosome infection, potentiates PZQ-mediated parasite clearance, and reduces chemotherapy-induced proinflammatory mediator production.
The Journal of Immunology 02/2003; 170(1):470-6. · 5.79 Impact Factor
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ABSTRACT: Infection of mice with Schistosoma mansoni delays the resolution of cutaneous lesions and parasitaemia during Leishmania major infection. In contrast, L. major infection does not appear to alter the course of schistosomiasis. Analysis of the cytokine responses in the draining lymph nodes (LN) indicates that, while L. major infection had no effect on schistosome-specific interleukin (IL)-4 production by mesenteric LN (MLN) cells, coinfection with S. mansoni resulted in decreased leishmania-induced interferon (IFN)-gamma, tumour necrosis factor-alpha and nitric oxide production by popliteal LN (PLN) cells 4 weeks after L. major infection. In addition, PLN cells produced higher levels of IL-4 4 weeks after L. major infection in coinfected mice. Finally, IFN-gamma-stimulated macrophages isolated from S. mansoni-infected mice were impaired in their ability to kill L. major after in vitro infection. These results suggest that pre-existence of a strong Th2 response-dominated infection can alter the responses to Th1-inducing pathogens at peripheral sites and impair Th1-mediated effector functions.
Parasite Immunology 08/2002; 24(7):339-45. · 2.60 Impact Factor
