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Oxidative stress (OS) stimulates autophagy in different cellular systems, but it remains controversial if this rule can be generalized. We have analyzed the effect of chronic OS induced by the parkinsonian toxin paraquat (PQ) on autophagy in astrocytoma cells and primary astrocytes, which represent the first cellular target of neurotoxins in the brain. PQ decreased the basal levels of LC3-II and LC3-positive vesicles, and its colocalization with lysosomal markers, both in the absence and presence of chloroquine. This was paralleled by increased number and size of SQSTM1/p62 aggregates. Downregulation of autophagy was also observed in cells chronically exposed to hydrogen peroxide or nonlethal concentrations of PQ, and it was associated with a reduced astrocyte capability to protect dopaminergic cells from OS in co-cultures. Surprisingly, PQ treatment led to inhibition of MTOR, activation of MAPK8/JNK1 and MAPK1/ERK2-MAPK3/ERK1 and upregulation of BECN1/Beclin 1 expression, all signals typically correlating with induction of autophagy. Reduction of OS by NMDPEF, a specific NQO2 inhibitor, but not by N-acetylcysteine, abrogated the inhibitory effect of PQ and restored autophagic flux. Activation of NQO2 by PQ or menadione and genetic manipulation of its expression confirmed the role of this enzyme in the inhibitory action of PQ on autophagy. PQ did not induce NFE2L2/NRF2, but when it was co-administered with NMDPEF NFE2L2 activity was enhanced in a SQSTM1-independent fashion. Thus, a prolonged OS in astrocytes inhibits LC3 lipidation and impairs autophagosome formation and autophagic flux, in spite of concomitant activation of several pro-autophagic signals. These findings outline an unanticipated neuroprotective role of astrocyte autophagy and identify in NQO2 a novel pharmacological target for its positive modulation.

The clinical development of locally and advanced non-small cell lung cancer (NSCLC) suffers from a lack of biomarkers as a guide in the selection of optimal prognostic prediction. Circulating Tumour Cells (CTCs) are correlated to prognosis and show efficacy in cancer monitoring in patients. However, their enumeration alone might be inadequate; it might also be critical to understand the viability, the apoptotic state and the kinetics of these cells. Here, we report what we believe to be a new and selective approach to visually detect tumour specific CTCs. Firstly, using labelled human lung cancer cells, we detected a specific density interval in which NSCL-CTCs were concentrated. Secondly, to better characterize CTCs in respect to their heterogeneous composition and tumour reference, blood and tumour biopsy were performed on specimens taken from the same patient. The approach consisted in comparing phenotype profile of CTCs, and their progenitor Tumour Stem Cells, (TSCs). Moreover, NSCL-CTCs were cultivated in short-time human cultures to provide response to drug sensitivity. Our bimodal approach allowed to reveal two items. Firstly, that one part of a tumour, proximal to the bronchial structure, displays a predominance of CD133+. Secondly, specific NSCL-CTCs Epithelial Cell Adhesion Molecule (EpCAM)+CD29+ can be used as a negative prognostic factor as well the high expression of CTCs EpCAM+. These data were confirmed by drug-sensitivity tests, in vitro, and by the survival curves, in vivo.

BACKGROUND AND PURPOSE The mechanisms of paraquat (PQ)-induced toxicity are poorly understood and PQ poisoning is often fatal due to a lack of effective antidotes. In this study we report the effects of N-[2-(2-methoxy-6H-dipyrido{2,3-a:3,2-e}pyrrolizin-11-yl)ethyl]-2-furamide (NMDPEF), a melatonin-related inhibitor of quinone oxidoreductase2 (QR2) on the toxicity of PQ in vitro & in vivo. EXPERIMENTAL APPROACH Prevention of PQ-induced toxicity was tested in different cells, including primary pneumocytes and astroglial U373 cells. Cell death and reactive oxygen species (ROS) were analysed by flow cytometry and fluorescent probes. QR2 silencing was achieved by lentiviral shRNAs. PQ (30 mg·kg(-1)) and NMDPEF were administered i.p. to Wistar rats and animals were monitored for 28 days. PQ toxicity in the substantia nigra (SN) was tested by a localized microinfusion and electrocorticography. QR2 activity was measured by fluorimetry of N-benzyldihydronicotinamide oxidation. KEY RESULTS NMDPEF potently antagonized non-apoptotic PQ-induced cell death, ROS generation and inhibited cellular QR2 activity. In contrast, the cytoprotective effect of melatonin and apocynin was limited and transient compared with NMDPEF. Silencing of QR2 attenuated PQ-induced cell death and reduced the efficacy of NMDPEF. Significantly, NMDPEF (4.5 mg·kg(-1)) potently antagonized PQ-induced systemic toxicity and animal mortality. Microinfusion of NMDPEF into SN prevented severe behavioural and electrocortical effects of PQ which correlated with inhibition of malondialdehyde accumulation in cells and tissues. CONCLUSIONS AND IMPLICATIONS NMDPEF protected against PQ-induced toxicity in vitro and in vivo, suggesting a key role for QR2 in the regulation of oxidative stress., (© 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.)

Background and Purpose: Tianeptine is an antidepressant affecting the glutamatergic system. In spite of its proven clinical efficacy, molecular effects of tianeptine are not entirely clear. Tianeptine modulates cytokine expression in the CNS and protects the hippocampus from chronic stress effects. HIV infection is associated with inflammation and neuronal loss, causing HIV-associated dementia (HAD). The human immunodeficiency virus type-1 glycoprotein gp120 has been proposed as a likely aetiological agent of HAD. In this study, we determined whether tianeptine protects astroglial cells from the neurodegenerative effects of gp120., Experimental Approach: Human astroglial cells were treated with gp120 and tianeptine, and viability and apoptosis was monitored by TUNEL, annexin V, and activated caspase-3 staining and flow cytometry. Protein levels of glutamine synthase (GS), inducible and constitutive nitric oxide synthases (iNOS, cNOS) and nuclear factor κB (NF-κB) pathway were determined by Western blot analysis. The respective activities were assessed indirectly by measuring glutamine and nitrite concentrations or by luciferase reporter assays., Key Results: Tianeptine showed an anti-apoptotic effect and prevented caspase-3 activation by gp120. The mechanism of tianeptine's action involved GS and cNOS stabilization and iNOS suppression. Moreover, tianeptine increased IκB-α levels in the absence of gp120 and blocked its degradation in response to gp120. This correlated with the suppression of basal and gp120-induced NF-κB transcriptional activity., Conclusions and Implications: Tianeptine clearly exerts neuroprotective effects in vitro by suppressing the molecular pro-inflammatory effects of gp120. Studies in animal models should be performed to evaluate the potential of tianeptine as a treatment for HAD., (© 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.)