Nicotinaldehyde, a Novel Precursor of NAD Biosynthesis, Abrogates the Anti-Cancer Activity of an NAD-Lowering Agent in Leukemia.

Targeting NAD depletion in cancer cells has emerged as an attractive therapeutic strategy for cancer treatment, based on the higher reliance of malignant vs. healthy cells on NAD to sustain their aberrant proliferation and altered metabolism. NAD depletion is exquisitely observed when NAMPT, a key enzyme for the biosynthesis of NAD, is inhibited. Growing evidence suggests that alternative NAD sources present in a tumor environment can bypass NAMPT and render its inhibition ineffective. Here, we report the identification of nicotinaldehyde as a novel precursor that can be used for NAD biosynthesis by human leukemia cells. Nicotinaldehyde supplementation replenishes the intracellular NAD level in leukemia cells treated with NAMPT inhibitor APO866 and prevents APO866-induced oxidative stress, mitochondrial dysfunction and ATP depletion. We show here that NAD biosynthesis from nicotinaldehyde depends on NAPRT and occurs via the Preiss-Handler pathway. The availability of nicotinaldehyde in a tumor environment fully blunts the antitumor activity of APO866 in vitro and in vivo. This is the first study to report the role of nicotinaldehyde in the NAD-targeted anti-cancer treatment, highlighting the importance of the tumor metabolic environment in modulating the efficacy of NAD-lowering cancer therapy

Experimental and numerical investigation of the weld repair of superplastic forming dies

Issu de : AMPT 2003 - International conference on advances in materials and processing technologies, Dublin, IRELAND, July 8-11, 2003International audienceSuperplastic forming process (SPF) is an advanced process conducted at high temperature using moderate strain rates, typically used for shaping TAW sheets for aerospace applications. Thermomechanical stresses on the forming dies due to successive forming cycles may result in the earl), degradation and even fracture of SPF tools through fatigue crack propagation. To reduce cost and extend service life. dies are generally weld-repaired and subsequently re-used in the typical severe conditions of SPF. The implementation of robust, easy processing welding techniques resulting in high quality repair able to sustain cumulative thermomechanical stresses is of utmost concern to SPF parts manufacturers. The paper focuses on the development of an automated TIG technique to weld repair high nickel, high chromium heat resistant alloys based on a complementary approach including thermal instrumentation, numerical simulation using Sysweld(TM) and metallurgical investigation: this former being performed on either as-received, repaired and repaired plus damaged materials

Activation of Bone Marrow-Derived Cells Angiotensin (Ang) II Type 1 Receptor by Ang II Promotes Atherosclerotic Plaque Vulnerability.

Angiotensin (Ang) II triggers vulnerable atherosclerotic plaque development. Bone marrow (BM)-derived cells are key players in atherogenesis but whether Ang II induces plaque vulnerability directly through Ang II type 1 receptor (AT1R) activation on these cells remains to be clarified. In the present study, we investigated whether a lack of AT1R on BM-derived cells might affect Ang II-mediated vulnerable plaque development. The 2-kidney, 1-clip (2K1C) model (Ang II-dependent mouse model of advanced atherosclerosis and vulnerable plaques) was generated in ApoE <sup>-/-</sup> mice transplanted with AT1aR <sup>-/-</sup> or AT1aR <sup>+/+</sup> BM. Plasma cholesterol as well as hepatic mRNA expression levels of genes involved in cholesterol metabolism were significantly lower in 2K1C mice transplanted with AT1aR <sup>-/-</sup> BM than in controls. Atherosclerotic lesions were significantly smaller in AT1aR <sup>-/-</sup> BM 2K1C mice (-79% in the aortic sinus and -71% in whole aorta compared to controls). Plaques from AT1aR <sup>-/-</sup> BM 2K1C mice exhibited reduced lipid core/fibrous cap and macrophage/smooth muscle cells ratios (-82% and -88%, respectively), and increased collagen content (+70%), indicating a more stable phenotype. Moreover, aortic mRNA levels of pro-inflammatory cytokines IL-12p35, IL-1β, and TNF-α were significantly reduced in AT1aR <sup>-/-</sup> BM 2K1C mice. No significant differences in either the number of circulating Ly6C <sup>high</sup> inflammatory monocytes and Ly6C <sup>low</sup> resident anti-inflammatory monocyte subsets, or in mRNA levels of aortic M1 or M2 macrophage markers were observed between the two groups. No significant differences were observed in splenic mRNA levels of T cell subsets (Th1, Th2, Th17 and Treg) markers between the two groups. In conclusion, direct AT1R activation by Ang II on BM-derived cells promotes hepatic mRNA expression of cholesterol-metabolism-related genes and vascular mRNA expression of pro-inflammatory cytokines that may lead to plaque instability

A novel anti-CD19 monoclonal antibody (GBR 401) with high killing activity against B cell malignancies.

BACKGROUND: CD19 is a B cell lineage specific surface receptor whose broad expression, from pro-B cells to early plasma cells, makes it an attractive target for the immunotherapy of B cell malignancies. In this study we present the generation of a novel humanized anti-CD19 monoclonal antibody (mAb), GBR 401, and investigate its therapeutic potential on human B cell malignancies. METHODS: GBR 401 was partially defucosylated in order to enhance its cytotoxic function. We analyzed the in vitro depleting effects of GBR 401 against B cell lines and primary malignant B cells from patients in the presence or in absence of purified NK cells isolated from healthy donors. In vivo, the antibody dependent cellular cytotoxicity (ADCC) efficacy of GBR 401 was assessed in a B cell depletion model consisting of SCID mice injected with healthy human donor PBMC, and a malignant B cell depletion model where SCID mice are xenografted with both primary human B-CLL tumors and heterologous human NK cells. Furthermore, the anti-tumor activity of GBR 401 was also evaluated in a xenochimeric mouse model of human Burkitt lymphoma using mice xenografted intravenously with Raji cells. Pharmacological inhibition tests were used to characterize the mechanism of the cell death induced by GBR 401. RESULTS: GBR 401 exerts a potent in vitro and in vivo cytotoxic activity against primary samples from patients representing various B-cell malignancies. GBR 401 elicits a markedly higher level of ADCC on primary malignant B cells when compared to fucosylated similar mAb and to Rituximab, the current anti-CD20 mAb standard immunotherapeutic treatment for B cell malignancies, showing killing at 500 times lower concentrations. Of interest, GBR 401 also exhibits a potent direct killing effect in different malignant B cell lines that involves homotypic aggregation mediated by actin relocalization. CONCLUSION: These results contribute to consolidate clinical interest in developing GBR 401 for treatment of hematopoietic B cell malignancies, particularly for patients refractory to anti-CD20 mAb therapies

A critical role of autophagy in antileukemia/lymphoma effects of APO866, an inhibitor of NAD biosynthesis.

APO866, an inhibitor of NAD biosynthesis, exhibits potent antitumor properties in various malignancies. Recently, it has been shown that APO866 induces apoptosis and autophagy in human hematological cancer cells, but the role of autophagy in APO866-induced cell death remains unclear. Here, we report studies on the molecular mechanisms underlying APO866-induced cell death with emphasis on autophagy. Treatment of leukemia and lymphoma cells with APO866 induced both autophagy, as evidenced by an increase in autophagosome formation and in SQSTM1/p62 degradation, but also increased caspase activation as revealed by CASP3/caspase 3 cleavage. As an underlying mechanism, APO866-mediated autophagy was found to deplete CAT/catalase, a reactive oxygen species (ROS) scavenger, thus promoting ROS production and cell death. Inhibition of autophagy by ATG5 or ATG7 silencing prevented CAT degradation, ROS production, caspase activation, and APO866-induced cell death. Finally, supplementation with exogenous CAT also abolished APO866 cytotoxic activity. Altogether, our results indicated that autophagy is essential for APO866 cytotoxic activity on cells from hematological malignancies and also indicate an autophagy-dependent CAT degradation, a novel mechanism for APO866-mediated cell killing. Autophagy-modulating approaches could be a new way to enhance the antitumor activity of APO866 and related agents

Transfer of human systemic lupus erythematosus in severe combined immunodeficient (SCID) mice

To study the role of peripheral blood leukocytes (PBL) in the pathogenesis of human systemic lupus erythematosus (SLE), we transferred PBL from 5 SLE patients into 15 severe combined immunodeficiency (SCID) mice. Such reconstituted mice showed long-term presence of auto-antibodies characteristic of the donor in their sera, as well as human immunoglobulin deposition, and in some cases mouse C3, in the renal glomeruli. SCID mice repopulated with PBLs from normal donors do not develop serologic abnormalities or immunodeposits. It is concluded that human SLE serology and some associated renal changes can be reproduced solely by PBL transferred from afflicted patients, and that SCID-human-SLE mice may serve as an in vivo laboratory model for the study of human SLE

Gut microbiota severely hampers the efficacy of NAD-lowering therapy in leukemia

: Most cancer cells have high need for nicotinamide adenine dinucleotide (NAD+) to sustain their survival. This led to the development of inhibitors of nicotinamide (NAM) phosphoribosyltransferase (NAMPT), the rate-limiting NAD+ biosynthesis enzyme from NAM. Such inhibitors kill cancer cells in preclinical studies but failed in clinical ones. To identify parameters that could negatively affect the therapeutic efficacy of NAMPT inhibitors and propose therapeutic strategies to circumvent such failure, we performed metabolomics analyses in tumor environment and explored the effect of the interaction between microbiota and cancer cells. Here we show that tumor environment enriched in vitamin B3 (NAM) or nicotinic acid (NA) significantly lowers the anti-tumor efficacy of APO866, a prototypic NAMPT inhibitor. Additionally, bacteria (from the gut, or in the medium) can convert NAM into NA and thus fuel an alternative NAD synthesis pathway through NA. This leads to the rescue from NAD depletion, prevents reactive oxygen species production, preserves mitochondrial integrity, blunts ATP depletion, and protects cancer cells from death.Our data in an in vivo preclinical model reveal that antibiotic therapy down-modulating gut microbiota can restore the anti-cancer efficacy of APO866. Alternatively, NAphosphoribosyltransferase inhibition may restore anti-cancer activity of NAMPT inhibitors in the presence of gut microbiota and of NAM in the diet

Study of Early Elevated Gas6 Plasma Level as a Predictor of Mortality in a Prospective Cohort of Patients with Sepsis.

Growth arrest-specific gene 6 (Gas6), a vitamin K-dependent protein interacting with anionic phospholipids and TAM tyrosine kinase receptors, is elevated in plasma of septic patients. Previous studies did not find different levels between survivors and non-survivors at admission because either they included a low number of patients (<50) or a low number of non-survivors (5%). To determine, in a larger cohort of septic patients comprising an expected number of non-survivors, the performance of the plasma level of Gas6 and its soluble receptor Axl (sAxl) within 24 hours of admission to predict in-ICU mortality. Septic adults with or without shock. Gas6 and sAxl were prospectively measured by ELISA at day 0, 3, 7, and then weekly until discharge or death. We evaluated 129 septic patients, including 82 with and 47 without shock, with in-ICU mortality rate of 19.4% and in-hospital mortality rate of 26%. Gas6 level was higher in non-survivors than in survivors (238 vs. 167%, P = 0.003); this difference remained constant during the ICU stay. The area under the ROC curve for Gas6 (0.695 [95% CI: 0.58-0.81]) was higher than for sAxl, procalcitonin, CRP, IL-1beta, IL-6 and-alpha, and slightly higher than for IL-8, IL-10, SOFA and APACHEII scores in predicting in-ICU mortality. Considering 249% as a cut-off value, Gas6 measurement had a negative predictive value for mortality of 87%. It seems that Gas6 plasma level within 24 hours of ICU admission may predicts in-ICU mortality in patients with sepsis. If our result are confirmed in external validation, Gas6 plasma level measurement could contribute to the identification of patients who may benefit most from more aggressive management