51 research outputs found

    A Functional Signature Ontology (FUSION) screen detects an AMPK inhibitor with selective toxicity toward human colon tumor cells

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    AMPK is a serine threonine kinase composed of a heterotrimer of a catalytic, kinase-containing α and regulatory β and γ subunits. Here we show that individual AMPK subunit expression and requirement for survival varies across colon cancer cell lines. While AMPKα1 expression is relatively consistent across colon cancer cell lines, AMPKα1 depletion does not induce cell death. Conversely, AMPKα2 is expressed at variable levels in colon cancer cells. In high expressing SW480 and moderate expressing HCT116 colon cancer cells, siRNA-mediated depletion induces cell death. These data suggest that AMPK kinase inhibition may be a useful component of future therapeutic strategies. We used Functional Signature Ontology (FUSION) to screen a natural product library to identify compounds that were inhibitors of AMPK to test its potential for detecting small molecules with preferential toxicity toward human colon tumor cells. FUSION identified 5′-hydroxy-staurosporine, which competitively inhibits AMPK. Human colon cancer cell lines are notably more sensitive to 5′-hydroxy-staurosporine than are non-transformed human colon epithelial cells. This study serves as proof-of-concept for unbiased FUSION-based detection of small molecule inhibitors of therapeutic targets and highlights its potential to identify novel compounds for cancer therapy development

    Late Cenozoic tephrostratigraphy offshore the southern Central American Volcanic Arc: 2. Implications for magma production rates and subduction erosion

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    Pacific drill sites offshore Central America provide the unique opportunity to study the evolution of large explosive volcanism and the geotectonic evolution of the continental margin back into the Neogene. The temporal distribution of tephra layers established by tephrochonostratigraphy in Part 1 indicates a nearly continuous highly explosive eruption record for the Costa Rican and the Nicaraguan volcanic arc within the last 8 M.y. The widely distributed marine tephra layers comprise the major fraction of the respective erupted tephra volumes and masses thus providing insights into regional and temporal variations of large-magnitude explosive eruptions along the southern Central American Volcanic Arc (CAVA). We observe three pulses of enhanced explosive magmatism between 0-1 Ma at the Cordillera Central, between 1-2 Ma at the Guanacaste and at >3 Ma at the Western Nicaragua segments. Averaged over the long-term the minimum erupted magma flux (per unit arc length) is ∼0.017 g/ms. Tephra ages, constrained by Ar-Ar dating and by correlation with dated terrestrial tephras, yield time-variable accumulation rates of the intercalated pelagic sediments with four prominent phases of peak sedimentation rates that relate to tectonic processes of subduction erosion. The peak rate at >2.3 Ma near Osa particularly relates to initial Cocos Ridge subduction which began at 2.91±0.23 Ma as inferred by the 1.5 M.y. delayed appearance of the OIB geochemical signal in tephras from Barva volcano at 1.42 Ma. Subsequent tectonic re-arrangements probably involved crustal extension on the Guanacaste segment that favored the 2-1 Ma period of unusually massive rhyolite production

    An analysis of clinical characteristics in genetically linked migraine-affected pedigrees

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    Migraine is a common complex disorder characterized by severe recurrent headache and usually accompanied by nausea and vomiting. Previous studies in our laboratory have utilized three large multigenerational Australian pedigrees affected with migraine to indicate that the disease is genetically heterogeneous, with linkage results implicating genomic susceptibility regions on both chromosomes 19p and Xq. The present study explores the possibility of a correlation between genetic and clinical heterogeneity in these affected pedigrees. Specifically, the clinical characteristics of migraine including subtype, age of onset, frequency, duration, and disease symptoms were compared between the migraine pedigrees, and gender differences were also assessed. Our exploratory analyses revealed no significant differences in any of the clinical characteristics tested between the chromosome 19-linked family and the two X-linked families. Also, we did not detect any differences in male vs. female clinical features for these pedigrees. In conclusion, migraine is considered to be a clinically and genetically heterogeneous disorder; however, our study provided no conclusive evidence that variation in genomic susceptibility region is related to heterogeneity at the clinical level in these migraine-affected pedigrees

    Light-sheet microscopy as a tool to understanding the behaviour of Polyion complex micelles for drug delivery

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    © The Royal Society of Chemistry. Polyelectrolyte-protein complexes are widely used to deliver therapeutic proteins. Here, we present a method for imaging the release of drugs from polyion complex (PIC) micelles in 3D tumour spheroids using light-sheet microscopy. A negatively charged block copolymer was condensed with a positively charged model drug, hen egg white lysozyme (HEWL) by electrostatic interaction. We were able to observe the distribution of polymer and protein within the entire tumour spheroid, showing that the protein was released from the polyelectrolyte complex upon cell internalization at the peripheral cell layer of the spheroid
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