BackgroundCell 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 β (GSK3β) is a new pathway supporting the chemoresistance of leukemic cells adhered to fibronectin.Methodology and Principal FindingsWe show here that in conditions of serum starvation, the fibronectin receptor α5β1 integrin, but not α4β1, induced activation of GSK3β through Ser-9 dephosphorylation in adherent U937 cells. The GSK3β-dependent survival pathway occurred in adherent leukemic cells from patients but not in the HL-60 and KG1 cell lines. In adhesion, activated GSK3β was found in the cytosol/plasma membrane compartment and was co-immunoprecipitated with α5 integrin, the phosphatase PP2A and the scaffolding protein RACK1. PP2A and its regulatory subunit B' regulated the Ser-9 phosphorylation of GSK3β. In adherent leukemic cells, α5β1 integrin but not α4β1 upregulated the resistance to TNFα-induced apoptosis. Both extrinsic and intrinsic apoptotic pathways were under the control of α5β1 and GSK3β.Conclusions and SignificanceOur data show that, upon serum starvation, α5β1 integrin engagement could regulate specific pro-survival functions through the activation of GSK3β.

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The results of the present investigation indicate that J. Phoenicea possesses hepatoprotective activity and this effect was may be due to its antioxidant properties.

Therapeutic resistance of acute myeloid leukemia stem cells, enriched in the CD34 þ 38 À 123 þ progenitor population, is supported by extrinsic factors such as the bone marrow niche. Here, we report that when adherent onto fibronectin or osteoblast components, CD34 þ 38 À 123 þ progenitors survive through an integrin-dependent activation of glycogen synthase kinase 3b (GSK3b) by serine 9-dephosphorylation. Strikingly, GSK3b-mediated survival was restricted to leukemic progenitors from female patients. GSK3b inhibition restored sensitivity to etoposide, and impaired the clonogenic capacities of adherent leukemic progenitors from female patients. In leukemic progenitors from female but not male patients, the scaffolding protein RACK1, activated downstream of a 5 b 1 -integrin engagement, was specifically upregulated and controlled GSK3b activation through the phosphatase protein phosphatase 2A (PP2A). In a mirrored manner, survival of adherent progenitors (CD34 þ 38 À ) from male but not female healthy donors was partially dependent on this pathway. We conclude that the GSK3b-dependent survival pathway might be sex-specific in normal immature population and flip-flopped upon leukemogenesis. Taken together, our results strengthen GSK3b as a promising target for leukemic stem cell therapy and reveal gender differences as a new parameter in anti-leukemia therapy.

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Aqueous extract (AE) of Hammada scoparia leaves was chemically characterized and its hepatoprotective activities were investigated in vivo in rat model. Wistar rats were treated daily with 35% ethanol solution (3 g/kg/day) during 4 weeks and fed with basal diet or basal diet containing AE (200 mg/kg/day). Control rats were treated with saline solution and fed with basal diet. The bioactivity of AE against ethanol-induced oxidative stress in rat liver was studied in order to explore its hepatoprotective effects. H. scoparia extract used at 200 mg/kg body weight significantly prevented the effects of ethanol, which induced a hepatic pathological damage and increased the levels of the serum markers of the enzymes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). Concomitantly, with these changes, this extract also prevented ethanol-induced oxidative stress in the rat liver as evidenced by the decreased lipid peroxidation level, a considerable decrease in the activities of AST, ALT and ALP and restoring the activities of antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. These biochemical changes were consistent with histopathological observations suggesting marked hepatoprotective effect of the AE of H. scoparia.

In this study, we investigated the protective effects of Peganum harmala seeds extract (CPH) against chronic ethanol treatment. Hepatotoxicity was induced in male Wistar rats by administrating ethanol 35% (4 g/kg/day) for 6 weeks. CPH was co-administered with ethanol, by intraperitonial (IP) injection, at a dose of 10 mg/kg bw/day. Control rats were injected by saline solution (NaCl 9‰). Chronic ethanol administration intensified lipid peroxidation monitored by an increase of TBARS level in liver. Ethanol treatment caused also a drastic alteration in antioxidant defence system; hepatic superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities. A co-administration of CPH during ethanol treatment inhibited lipid peroxidation and improved antioxidants activities. However, treatment with P. harmala extract protects efficiently the hepatic function of alcoholic rats by the considerable decrease of aminotransferase contents in serum of ethanol-treated rats.

To investigate the molecular mechanism underlying the neuroprotective effect of lithium on cells, in this study, we exposed SH-SY5Y cells to 0.5 mmol/L lithium carbonate (Li2CO2) for 25–50 weeks and then detected the expression levels of some neurobiology related genes and post-translational modifications of stress proteins in SH-SY5Y cells. cDNA arrays showed that pyruvate kinase 2 (PKM2) and calmodulin 3 (CaM 3) expression levels were significantly down-regulated, phosphatase protein PP2A expression was lightly down-regulated, and casein kinase II (CK2), threonine/tyrosine phosphatase 7 (PYST2), and dopamine beta-hydroxylase (DBH) expression levels were significantly up-regulated. Besides, western blot analysis of stress proteins (HSP27, HSP70, GRP78 and GRP94) showed an over-expression of two proteins: a 105 kDa protein which is a hyper-phosphorylated isoform of GRP94, and a 108 kDa protein which is a phosphorylated tetramer of HSP27. These results suggest that the neuroprotective effects of lithium are likely related to gene expressions and post-translational modifications of proteins cited above.