40 research outputs found

    Cytoplasmic levels of cFLIP determine a broad susceptibility of breast cancer stem/progenitor-like cells to TRAIL

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    Background The clinical application of TRAIL receptor agonists as a novel cancer therapy has been tempered by heterogeneity in tumour responses. This is illustrated in breast cancer, where TRAIL is cytotoxic in cell lines of mesenchymal origin but refractory in lines with an epithelial-like phenotype. However, it is now evident that intra-tumour heterogeneity includes a minority subpopulation of tumour-initiating stem/progenitor-like cells (CSCs) that possess mesenchymal characteristics. We hypothesised therefore that TRAIL may target these phenotypically distinct CSC-like cells that are common to most - if not all - breast cancers, thus impacting on the source of malignancy in a much broader range of breast tumour subtypes than previously envisaged. Methods We used colony formation, tumoursphere, flow cytometry and xenograft tumour initiation assays to observe the TRAIL sensitivity of CSC-like cells in a panel of two mesenchymal-like (TRAIL-sensitive) and four epithelial-like (TRAIL-resistant) breast cancer cell lines. Subcellular levels of the endogenous TRAIL inhibitor, cFLIP, were determined by western blot and immunofluorescence microscopy. The effect of the subcellular redistribution of cFLIP on TRAIL sensitivity and Wnt signalling was determined using cFLIP localisation mutants and the TOPFlash reporter assay respectively. Results TRAIL universally suppressed the clonal expansion of stem/progenitors in all six of the breast cancer cell lines tested, irrespective of their phenotype or overall sensitivity to TRAIL. A concomitant reduction in tumour initiation was confirmed in the TRAIL-resistant epithelial cell line, MCF-7, following serial dilution xenotransplantation. Furthermore TRAIL sensitivity of breast CSCs was inversely proportional to the relative cytoplasmic levels of cFLIP while overexpression of cFLIP in the cytosol using subcellular localization mutants of cFLIP protected these cells from cytotoxicity. The accumulation of nuclear cFLIP on the other hand did not influence TRAIL cytotoxicity but instead promoted Wnt-dependent signalling. Conclusion These data propose a novel role for TRAIL as a selective CSC agent with a broad specificity for both epithelial and mesenchymal breast tumour subtypes. Furthermore we identify a dual role for cFLIP in the maintenance of breast CSC viability, dependent upon its subcellular distribution

    Adaptability of Crop Insurance Schemes in Tamil Nadu

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    The experiences gained in the execution of various crop insurance products in India have been described along with the ways to redesign the strategies for effective implementation of such crop insurance products. The study is based on the data collected from 90 farmers covered under National Agricultural Insurance Scheme (NAIS) in three selected districts in Tamil Nadu, viz. Nagappattinam, Vellore and Madurai and 30 farmers covered under Varsha Bima, a weather-based insurance product in the Nagapattinam district. The major problems in the implementation of NAIS, as indicated by respondents, are: poor awareness about the scheme, delay in settlement of claims, complex procedure, high premium rate and wide variation between yields of actual and crop-cutting experiment farms. In the case of Varsha Bima scheme implemented in the Nagapattinam district, the major problems faced by the farmers are: non – availability of the benefit since the implementation of the scheme, poor awareness about the details of weather insurance schemes, high premium rate and wide variation in rainfall between the farm and the Reference Weather Station. The study has offered several suggestions, based on farmers’ perceptions, to refine the existing crop insurance schemes in India

    Crystal structure of 3-({[(thiophen-2-yl)methylidene]hydrazinyl}carbonyl)pyridinium chloride dihydrate

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    In the title compound, C11H10N3OS+·Cl−·2H2O, the organic cation exhibits a dihedral angle of 21.26 (8)° between the mean planes of the pyridine and thiophene rings, and dihedral angles of 15.11 (9) and 6.49 (9)° between the mean planes of the hydrazide moiety and the pyridine and thiophene rings, respectively. In the crystal, the organic cation, the chloride counter-anion and the two water molecules of crystallization are linked through an intricate hydrogen-bonding network consisting of O—H...O, O—H...N, N—H...Cl, C—H...Cl, C—H...O, N—H...O, O—H...Cl and C—H...S interactions that consolidate a three-dimensional network

    Development, Interlaboratory Evaluations, and Application of a Simple, High-Throughput Shigella Serum Bactericidal Assay

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    Shigella is an important cause of diarrhea worldwide, and efforts are ongoing to produce a safe and effective Shigella vaccine. Although a clear immune correlate of protection has not been established, antibodies with bactericidal capacity may provide one means of protecting against shigellosis. Thus, it is important to measure the functional capacity of antibodies, as opposed to only binding activity. This article describes a simple, robust, and high-throughput serum bactericidal assay capable of measuring Shigella-specific functional antibodies in vitro. We show for the first time that this assay was successfully performed by multiple laboratories and generated highly comparable results, particularly when SBA titers were normalized using a reference standard. The serum bactericidal assay, along with a reference serum, should greatly facilitate Shigella vaccine development.Shigella is an important cause of diarrhea worldwide, with serotypes Shigella flexneri 2a, S. flexneri 3a, and Shigella sonnei demonstrating epidemiological prevalence. Many development efforts are focused on Shigella lipopolysaccharide (LPS)-based vaccines, as O antigen-specific conjugate vaccines are immunogenic and efficacious. Immunization with Shigella vaccines containing LPS can elicit antibodies capable of killing Shigella in a serotype-specific manner. Thus, to facilitate Shigella vaccine development, we have developed a serum bactericidal assay (SBA) specific for three Shigella serotypes that measures killing of target bacteria at multiple serum dilutions and in the presence of exogenous complement. The SBA has a high analytical throughput and uses simple technologies and readily available reagents. The SBA was characterized with human sera with bactericidal antibodies against S. flexneri 2a, S. flexneri 3a, and S. sonnei. Purified LPS of a homologous serotype, but not a heterologous serotype, inhibited bacterial killing. Assessment of precision found median intra-assay precision to be 13.3% and median interassay precision to be 19 to 30% for the three serotypes. The SBA is linear, with slight deviations for samples with low (~40) killing indices. The SBA was sensitive enough to allow about 100-fold predilution of serum samples. Repeat assays yielded results with less than 2-fold deviations, indicating the robustness of the assay. Assay results from four different laboratories were highly comparable when normalized with a reference serum. The Shigella SBA, combined with a reference serum, should facilitate the development of Shigella vaccines across the field

    Signals and pathways regulating nucleolar retention of novel putative nucleolar GTPase, NGP-1 (GNL-2)

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    NGP-1(GNL-2) is a putative GTPase, overexpressed in breast carcinoma and localized in the nucleolus. NGP-1 belongs to the MMR1-HSR1 family of large GTPases that are emerging as crucial coordinators of signaling cascades in different cellular compartments. The members of this family share very closely related G-domains, but the signals and pathways regulating their subcellular localization and their functional relevance remain unknown. To improve our understanding of the nuclear transport mechanism of NGP-1, we have identified two nucleolar localization signals (NoLS) that are independently shown to translocate NGP-1 as well the heterologous protein to the nucleolus. Site-specific mutagenesis and immunofluorescence studies suggest that the tandem repeats of positively charged amino acids are critical for NGP-1 NoLS function. Interestingly, amino-terminal (NGP-11-100) and carboxyl-terminal (NGP-1661-731) signals independently interact with receptors importin-β and importin-α, respectively. This investigation, for the first time, provides evidence that the interaction of importin-α with C-terminal NoLS (NGP-1661-731) was able to target the heterologous protein to the nucleolar compartment. Structural modeling analysis and alanine scanning mutagenesis of conserved G-domains suggest that G4 and G5 motifs are critical for GTP binding of NGP-1 and further show that the nucleolar localization of NGP-1 is regulated by a GTP gating-mediated mechanism. In addition, our data suggest that an ongoing transcription is essential for efficient localization of NGP-1 to the nucleolus. We have observed a high level of NGP-1 expression in the mitogen-activated primary human peripheral blood mononuclear cells (hPBMC) as well as in human fetal brain-derived neural precursor cells (hNPCs) in comparison to cells undergoing differentiation. Overall, the results suggest that multiple mechanisms are involved in the localization of NGP-1 to the nucleolus for the regulation of nucleolar function in cell growth and proliferation
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