A New α5β1 Integrin-Dependent Survival Pathway Through GSK3β Activation in Leukemic Cells

Cell survival mediated by integrin engagement has been implicated in cell adhesion-mediated drug resistance. We have recently demonstrated that the activation of glycogen synthase kinase 3 beta (GSK3beta) is a new pathway supporting the chemoresistance of leukemic cells adhered to fibronectin.We show here that in conditions of serum starvation, the fibronectin receptor alpha(5)beta(1) integrin, but not alpha(4)beta(1), induced activation of GSK3beta through Ser-9 dephosphorylation in adherent U937 cells. The GSK3beta-dependent survival pathway occurred in adherent leukemic cells from patients but not in the HL-60 and KG1 cell lines. In adhesion, activated GSK3beta was found in the cytosol/plasma membrane compartment and was co-immunoprecipitated with alpha(5) integrin, the phosphatase PP2A and the scaffolding protein RACK1. PP2A and its regulatory subunit B' regulated the Ser-9 phosphorylation of GSK3beta. In adherent leukemic cells, alpha(5)beta(1) integrin but not alpha(4)beta(1) upregulated the resistance to TNFalpha-induced apoptosis. Both extrinsic and intrinsic apoptotic pathways were under the control of alpha(5)beta(1) and GSK3beta.Our data show that, upon serum starvation, alpha(5)beta(1) integrin engagement could regulate specific pro-survival functions through the activation of GSK3beta

Adult Stromal Cells Derived from Human Adipose Tissue Provoke Pancreatic Cancer Cell Death both In Vitro and In Vivo

1932-6203 (Electronic) Journal Article Research Support, Non-U.S. Gov'tBACKGROUND: Normal tissue homeostasis is maintained by dynamic interactions between epithelial cells and their microenvironment. Disrupting this homeostasis can induce aberrant cell proliferation, adhesion, function and migration that might promote malignant behavior. Indeed, aberrant stromal-epithelial interactions contribute to pancreatic ductal adenocarcinoma (PDAC) spread and metastasis, and this raises the possibility that novel stroma-targeted therapies represent additional approaches for combating this malignant disease. The aim of the present study was to determine the effect of human stromal cells derived from adipose tissue (ADSC) on pancreatic tumor cell proliferation. PRINCIPAL FINDINGS: Co-culturing pancreatic tumor cells with ADSC and ADSC-conditioned medium sampled from different donors inhibited cancer cell viability and proliferation. ADSC-mediated inhibitory effect was further extended to other epithelial cancer-derived cell lines (liver, colon, prostate). ADSC conditioned medium induced cancer cell necrosis following G1-phase arrest, without evidence of apoptosis. In vivo, a single intra-tumoral injection of ADSC in a model of pancreatic adenocarcinoma induced a strong and long-lasting inhibition of tumor growth. CONCLUSION: These data indicate that ADSC strongly inhibit PDAC proliferation, both in vitro and in vivo and induce tumor cell death by altering cell cycle progression. Therefore, ADSC may constitute a potential cell-based therapeutic alternative for the treatment of PDAC for which no effective cure is available

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

GSK3bêta (clé de voûte des mécanismes de résistance au stress contrôlés par les intégrines dans les leucémies aiguës myéloïdes)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Focal adhesion kinase splice variants maintain primitive acute myeloid leukemia cells through altered wnt signaling.

International audienceFocal adhesion kinase (FAK) activity contributes to many advanced cancer phenotypes, but little is known about its role in human acute myeloid leukemia (AML). Here, we show that FAK splice variants are abnormally expressed in the primitive leukemic cells of poor prognosis AML patients. In the CD34(+) 38(-) 123(+) long-term culture-initiating cell-enriched leukemic cells of these patients, FAK upregulates expression of Frizzled-4 and phosphorylates Pyk2 to enable the required association of Pyk2 with the Wnt5a/Frizzled-4/LRP5 endocytosis complex and downstream activation of β-catenin, thereby replacing the Wnt3a-controlled canonical pathway used by normal hematopoietic stem cells. Transduction of primitive normal human hematopoietic cells with FAK splice variants induces a marked increase in their clonogenic activity and signaling via the Wnt5a-controlled canonical pathway. Targeting FAK or β-catenin efficiently eradicates primitive leukemic cells in vitro suggesting that FAK could be a useful therapeutic target for improved treatment of poor prognosis AML cases. STEM CELLS2012;30:1597-1610

α₅ integrin, PP2A and GSK3β are co-localized in adherent leukemic cells.

<p><b>A</b>- The Ser-9 phosphorylation of GSK3β was studied by Western blot in cytosolic (Ct) and membrane (Mb) compartments of U937 in adhesion or in suspension. <b>B</b>- The presence of GSK3β (and its Ser-9 phosphorylated form), PP2A (and its Tyr-307 phosphorylated form), the scaffolding protein RACK1 and the PI 3-kinase regulatory subunit p85 was checked by Western blot in α₅ immunoprecipitates from U937 in suspension (Susp.) or in adhesion (Adh.). The absence of flotillin in α₅ immunoprecipitate demonstrates specificity of the interactions between α₅ integrin, PP2A and GSK3β. Right panel (<i>input</i>) indicates the amounts of α₅ subunit and GSK3β proteins in the total lysates (Total) and in the supernatants (Sup.), before and after immunoprecipitation of α₅ respectively. Data are representative of three independent experiments.</p

GSK3β is differentially regulated by α₄β₁ and α₅β₁ integrins in leukemic cells.

<p><b>A</b>- Specificity and efficacy of siRNA integrins were checked by Western blot. <b>B</b>- Serum-starved U937 were allowed to adhere on fibronectin for 1 h and the Ser-9 phosphorylation state of GSK3β was compared to cells in suspension after downregulation of α₄ and α₅ expression by siRNA. SiC = non-targeting siRNA. Right panel shows the mean ± S.E.M. variations of the P(S9)GSK3β/GSK3β ratio analyzed by densitometry from three independent experiments. <b>C</b>- The phosphorylation state of GSK3β was studied in suspension or after adhesion of U937 on surfaces coated with fibronectin (Fn, 40 µg/ml), anti-α₄ (1 µg/ml) or -α₅ (clone P1D6 0.1 µg/ml; clone JBS5 0.2 µg/ml) antibodies in experimental conditions as for B. Adhesive capacities of U937 in each condition of coating were measured by colorimetry and are shown on right panel. Data are representative of three independent experiments.</p