Hypoxia switches glucose depletion-induced necrosis to phosphoinositide 3-kinase/Akt-dependent apoptosis in A549 lung adenocarcinoma cells
ABSTRACT In solid tumours, necrosis is commonly found in the core region in response to metabolic stress that results from oxygen and glucose depletion (OGD) due to insufficient vascularization and has been implicated in tumour progression. We have previously shown that metabolic stress due to glucose depletion (GD) induces necrosis and HMGB1 release through mitochondrial ROS production in A549 lung adenocarcinoma cells. In this study, we examined the effects of hypoxia on GD-induced necrosis and show that hypoxia prevented GD-induced mitochondrial ROS production, HMGB1 release, and necrosis and switched the cell death mode to apoptosis that is dependent on caspase-3 and -9. We further found that inhibition of ERK1/2 by U0126 abolished the effects of hypoxia to switch the cell death mode and to suppress mitochondrial ROS production, indicating an important role(s) of the ERK pathway in cell death mode determination. We also found that during OGD-induced apoptosis the prosurvival protein kinase Akt is activated and inhibition of Akt by the phosphoinositide 3-kinase (PI3K) inhibitors LY294002 and wortmannin prevent OGD-induced apoptosis, caspase-3 and -9 activation, and nuclear translocation of AIF and EndoG. Similar inhibitory effects of PI3K inhibitors were observed in A549 cells that underwent apoptosis when treated with GD in the presence of NAC (a general antioxidant) or catalase (a H(2)O(2) scavenger), or in the presence of active PKC by treatment with phorbol-12-myristate-13-acetate, indicating a crucial role(s) of the PI3K-Akt pathway in OGD-indcued apoptosis. In conclusion, our results demonstrate that hypoxia switches GD-induced necrosis to apoptosis and ERK1/2 and PI3K-Akt exert anti-necrotic and pro-apoptotic activities in the cell death, respectively.
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ABSTRACT: In search for compounds able to reduce cell adhesion-mediated drug resistance (CAM-DR), we studied effects of Hammada scoparia extracts on leukemic cells adherent or in suspension. We show that H. scoparia flavonoidic fraction and its compound rutin induce apoptosis specifically in adherent leukemic cells and abolish CAM-DR. Importantly, rutin inhibited survival of adherent leukemic progenitors (CD34(+)38(-)123(+)) but spared normal progenitors (CD34(+)38(-)). The pro-apoptotic effects of rutin were correlated with a decrease of active GSK3β and inhibitors of GSK3β reproduced rutin-induced cytotoxicity. This study uncovers the potential of H. scoparia flavonoids and rutin to overcome CAM-DR in acute myeloid leukemia.Leukemia research 08/2011; 35(8):1093-101. DOI:10.1016/j.leukres.2010.12.011 · 2.69 Impact Factor
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ABSTRACT: In this study, we determined the protective potential of trans resveratrol against oxygen-glucose deprivation (OGD) induced reactive oxygen species mediated apoptotic damages in PC12 cells. In vitro model of ischemic cerebral stroke was created by keeping cells in an OGD condition for 6h followed by 24h reoxygenation. Cells received biologically safe doses (5, 10, and 25 μM) of trans resveratrol in the following schedules for 24h prior to OGD; during 6h of OGD; for 24h post OGD and whole treatment group which starts from 24h before OGD and lasted to 24h post OGD. Anti-ischemic potential of trans resveratrol was assessed by measuring the regulation of lipid peroxidation, reactive oxygen species production, glutathione content, and expression (mRNA and protein) of apoptotic markers such as Bax, Bcl(2) and Caspase-3. Hypoxia inducible factor-1α (HIF-1α) was also assessed to correlate the changes with ischemic injuries. Significant (P<0.05) restoration in lipid peroxidation, reactive oxygen species, and glutathione content were observed following the treatment of trans resveratrol in cells receiving OGD and re-oxygenation. Changes induced by trans resveratrol could be correlated well with alterations in the expression of Bax, Bcl(2), Caspase-3 and HIF-1α. These results indicate that trans resveratrol administration attenuates free radical formation and mitochondria mediated apoptosis perhaps by regulating the expressions of Bax, Bcl(2,) and Caspase-3 in PC12 cells receiving OGD and re-oxygenation insult.European journal of pharmacology 05/2011; 666(1-3):5-11. DOI:10.1016/j.ejphar.2011.05.015 · 2.68 Impact Factor
- ACS Chemical Neuroscience 10/2012; · 4.21 Impact Factor