CIIA negatively regulates neuronal cell death induced by oxygen–glucose deprivation and reoxygenation

Brain ischemia causes neuronal injury leading to stroke and other related brain diseases. However, the precise mechanism of the ischemia-induced neuronal death remains unclear yet. In this study, we showed that CIIA suppressed neuronal cell death induced by oxygen and glucose deprivation followed by reoxygenation (OGD/R), which mimics ischemia and reperfusion in vivo, in neuroblastoma cell lines as well as primary cortical neurons. Furthermore, CIIA inhibited the OGD/R-induced stimulation of apoptosis signal-regulating kinase 1 (ASK1) and its downstream kinases including c-Jun amino-terminal kinase and p38 kinase, concomitantly blocking ASK1 homo-oligomerization and the binding between ASK1 and TRAF2. CIIA also repressed the OGD/R-induced activation of caspase-3 in neuronal cells. Taken together, our results suggest that CIIA attenuates neurotoxicity caused by OGD/R through inhibiting ASK1-dependent signaling events.     

Profilin potentiates chemotherapeutic agents mediated cell death via suppression of NF-κB and upregulation of p53

The molecular mechanism by which Profilin acts as a tumor suppressor is still unclear. Several chemotherapeutic agents, used till date either have unfavorable side effects or acquired resistance in tumor cells. Our findings show that Profilin enhances cell death mediated by several chemotherapeutic-agents. The activation of NF-κB and its dependent genes, mediated by paclitaxel and vinblastine, was completely inhibited in Profilin overexpressing cells. This inhibition was due to the Profilin mediated attenuation of IκBα degradation, thereby preventing p65 nuclear translocation and low NF-κB DNA binding activity.Moreover, Profilin increases level of p53 in the presence of known inducers, such as doxorubicin, vinblastine, and benzofuran. This increased p53 level leads to enhanced cell death as indicated by activation of caspases 3, 8, 9, which results in cleavage of PARP.Furthermore, knocking down of p53 in Profilin overexpressing cells leads to decreased cell death. Ectopic expression of Profilin in HCT116 p53 knock out cells showed lesser cell death as compared to the HCT116 p53 wild type cells. For the first time, we provide evidences, which suggest that Profilin synergizes with chemotherapeutic drugs to induce tumor cell death by regulating NF-κB and p53. Thus, modulation of Profilin may be a useful strategy for effective combination therapy.     

Valproic acid inhibits neural progenitor cell death by activation of NF-κB signaling pathway and up-regulation of Bcl-XL

Background  

At the beginning of neurogenesis, massive brain cell death occurs and more than 50% of cells are eliminated by apoptosis along with neuronal differentiation. However, few studies were conducted so far regarding the regulation of neural progenitor cells (NPCs) death during development. Because of the physiological role of cell death during development, aberration of normal apoptotic cell death is detrimental to normal organogenesis.     

Zfra affects TNF-mediated cell death by interacting with death domain protein TRADD and negatively regulates the activation of NF-κB,JNK1, p53 and WOX1 during stress response

Background  

Zfra is a 31-amino-acid zinc finger-like protein, which is known to regulate cell death by tumor necrosis factor (TNF) and overexpressed TNF receptor- or Fas-associated death domain proteins (TRADD and FADD). In addition, Zfra undergoes self-association and interacts with c-Jun N-terminal kinase 1 (JNK1) in response to stress stimuli. To further delineate the functional properties of Zfra, here we investigated Zfra regulation of the activation of p53, WOX1 (WWOX or FOR), NF-κB, and JNK1 under apoptotic stress.     

Restoration of miR-34a in p53 deficient cells unexpectedly promotes the cell survival by increasing NFκB activity

Upregulation of miR-34a by p53 is recently believed to be a key mediator in the pro-apoptotic effects of this tumor suppressor. We sought to determine whether restoration of miR-34a levels in p53 deficient cells could rescue the response to DNA damage. Compared with the p53 wildtype U2OS cells, miR-34a expression was much lower in p53 deficient Saos2 cells upon cisplatin treatment. Unexpectedly, delivery of miR-34a in Saos2 cells does not increase the cell sensitivity to apoptosis. This effect was mediated by direct downregulation of SirT1 expression by miR-34a, which in turn increased the NFκB activity. Inhibition of NFκB activity in Saos2 cells by Aspirin sensitized the miR-34a overexpressing cells to cell death. Thus, in tumors with p53 deficiency, miR-34a restoration alone confers drug resistance through Sirt1-NFκB pathway and combination of miR-34a and NFκB inhibitor could be considered as a promising therapeutic strategy.     

Curcumin inhibits cell proliferation of MDA-MB-231 and BT-483 breast cancer cells mediated by down-regulation of NFκB,cyclinD and MMP-1 transcription

Curcumin, an active constituent of turmeric, has been shown to possess inhibitory effect of cell proliferation and induction of apoptosis towards a board range of tumors. Cell inhibition activities of curcumin are behaved differently in various cell types. To investigate the mechanism basis for the cell inhibition of curcumin on breast cancer cell lines, we examine curcumin effect on NFκB, cell cycle regulatory proteins and matrix metalloproteinases (MMPs) in two breast cancer cell lines (MDA-MB-231 and BT-483). Cell proliferation was performed by water soluble tetrazolium WST-1 assay. The effect of curcumin's on the activity of matrix metalloproteinase-1, 3, 9 were analyzed by RT-PCR. Cell cycle regulatory protein including cyclin D1, CDK4 and p21 were examined by immunochemistry. The expressions of NFκB in breast cancer cells treated with curcumin were studied by immunochemistry and western blot. The results from WST-1 cell proliferation assay showed that curcumin exhibited the anti-proliferation effect on MDA-MB-231 and BT-483 cells in a time- and dose-dependent manner. In response to the treatment, while, the expression of cyclin D1 had declined in MDA-MB-231 and the expression of CDK4 in BT-483 had declined. MMP1 mRNA expression in BT-483 and MDA-MB-231 had significantly decreased in curcumin treatment group compared with control group. Our finding extrapolates the antitumor activity of curcumin in mediating the breast cancer cell proliferative rate and invasion by down-regulating the NFκB inducing genes.     

Curcumin protects against acute liver damage in the rat by inhibiting NF-κB,proinflammatory cytokines production and oxidative stress

Curcumin, an anti-inflammatory and antioxidant compound, was evaluated for its ability to suppress acute carbon tetrachloride-induced liver damage. Acute hepatotoxicity was induced by oral administration of CCl₄ (4 g/kg, p.o.). Curcumin treatment (200 mg/kg, p.o.) was given before and 2 h after CCl₄ administration. Indicators of necrosis (alanine aminotransferase) and cholestasis (γ-glutamyl transpeptidase and bilirubins) resulted in significant increases after CCl₄ intoxication, but these effects were prevented by curcumin treatment. As an indicator of oxidative stress, GSH was oxidized and the GSH/GSSG ratio decreased significantly by CCl₄, but was preserved within normal values by curcumin. In addition to its antioxidants properties, curcumin is capable of preventing NF-κB activation and therefore to prevent the secretion of proinflammatory cytokines. Therefore, in this study we determined the concentrations of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) mRNA, and NF-κB activation. CCl₄-administered rats depicted significant increases in TNF-α, IL-1β, and IL-6 production, while curcumin remarkably suppressed these mediators of inflammation in liver damage. These results were confirmed by measuring TNF-α, and IL-1β protein production using Western Blot analysis. Accordingly, these proteins were increased by CCl₄ and this effect was abolished by curcumin. Administration of CCl₄ induced the translocation of NF-κB to the nucleus; CCl₄ induced NF-κB DNA binding activity was blocked by curcumin treatment. These findings suggest that curcumin prevents acute liver damage by at least two mechanisms: acting as an antioxidant and by inhibiting NF-κB activation and thus production of proinflammatory cytokines.     

Dexmedetomidine improves acute stress-induced liver injury in rats by regulating MKP-1, inhibiting NF-κB pathway and cell apoptosis

Acute stress is a frequent and unpredictable disease for many animals. Stress is widely considered to affect liver function. However, the underlying mechanism by which dexmedetomidine (DEX) attenuates acute stress-induced liver injury in rats remains unclear. In this study, we used forced swimming for 15 min and acute 3-hr restraint stress model. Behavioral tests and changes in norepinephrine levels confirmed the successful establishment of the acute stress model. Acute stress-induced liver injury, evidenced by hematoxylin and eosin-stained pathological sections and increased serum aminotransferase and aspartate aminotransferase levels, was reduced in DEX-treated livers. Reactive oxygen species and oxidative stress levels were dramatically decreased with DEX treatment compared with acute stress-induced liver injury. DEX significantly reduced acute stress-induced liver inflammation and apoptosis, as assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and inflammation and apoptosis-related protein levels. DEX treatment also effectively inhibited acute stress-induced c-Jun N-terminal kinase (JNK), P38, and BAD signaling pathway activation, and significantly induced MKP-1 activation. Thus, DEX has a protective effect on acute-stress-induced liver injury by reducing inflammation and apoptosis, which suggests a potential clinical application for DEX in stress syndrome.     

Contribution of p38 MAPK, NF-κB and glucocorticoid signaling pathways to ER stress-induced increase in retinal endothelial permeability

Diabetic retinopathy (DR) is characterized by the development of intraretinal microvascular abnormalities. Endoplasmic reticulum (ER) stress is known to play a pathogenic role in vascular impairment in DR. The present study demonstrated that the treatment of human retinal endothelial cells with ER stress inducers such as thapsigargin (Tg) and tunicamycin (Tm) significantly increased the permeability of exogenously added FITC-dextran, accompanied by a decrease of transendothelial electrical resistance (TEER). The expression of claudin-5 among tight junction proteins was significantly decreased by the treatment with Tg or Tm. A p38 MAPK inhibitor, SB203580, and an NF-κB inhibitor, dexamethasone, significantly suppressed the Tg-induced down-regulation of claudin-5, decrease of TEER and leakage of added FITC-dextran. The translocation of NF-κB p65 subunit to the nucleus was also inhibited by the addition of SB203580 or dexamethasone. The effects of dexamethasone are thought to be due to the transrepression of the above signaling and direct regulation of claudin-5 gene.     

Neurobehavioral Toxicity Induced by Carbendazim in Rats and the Role of iNOS,Cox-2, and NF-κB Signalling Pathway

Neurochemical Research - Carbendazim (CBZ) is one of the most common fungicides used to fight plant fungal diseases, otherwise, it leaves residue on fruits, vegetables, and soil that contaminate...     

Apigenin induces apoptosis via extrinsic pathway,inducing p53 and inhibiting STAT3 and NFκB signaling in HER2-overexpressing breast cancer cells

Phytoestrogens are known to prevent tumor induction. But their molecular mechanisms of action are still unknown. This study aimed to examine the effect of apigenin on proliferation and apoptosis in HER2-expressing breast cancer cells. In our experiments, apigenin inhibited the proliferation of MCF-7 vec and MCF-7 HER2 cells. This growth inhibition was accompanied with an increase of sub G(0)/G(1) apoptotic fractions. Overexpression of HER2 did not confer resistance to apigenin in MCF-7 cells. Apigenin-induced extrinsic apoptosis pathway up-regulating the levels of cleaved caspase-8, and inducing the cleavage of poly (ADP-ribose) polymerase, whereas apigenin did not induce apoptosis via intrinsic mitochondrial apoptosis pathway since this compound did not decrease mitochondrial membrane potential maintaining red fluorescence and did not affect the levels of B-cell lymphoma 2 (BCL2) and Bcl-2-associated X protein. Moreover, apigenin reduced the tyrosine phosphorylation of HER2 (phospho-HER2 level) in MCF-7 HER2 cells, and up-regulated the levels of p53, phospho-p53 and p21 in MCF-7 vec and MCF-7 HER2 cells. This suggests that apigenin induces apoptosis through p53-dependent pathway. Apigenin also reduced the expression of phospho-JAK1 and phospho-STAT3 and decreased STAT3-dependent luciferase reporter gene activity in MCF-7 vec and MCF-7 HER2 cells. Apigenin decreased the phosphorylation level of IκBα in the cytosol, and abrogated the nuclear translocation of p65 within the nucleus suggesting that it blocks the activation of NFκB signaling pathway in MCF-7 vec and MCF-7 HER2 cells. Our study indicates that apigenin could be a potential useful compound to prevent or treat HER2-overexpressing breast cancer.     

TGF-β-activated kinase 1 promotes cell cycle arrest and cell survival of X-ray irradiated HeLa cells dependent on p21 induction but independent of NF-κB, p38 MAPK and ERK phosphorylations

Transforming growth factor-β-activated kinase 1 (TAK1) appears to play a role in inhibiting apoptotic death in response to multiple stresses. To assess the role of TAK1 in X-ray induced apoptosis and cell death, we irradiated parental and siRNA-TAK1-knockdown HeLa cells. Changes in gene expression levels with and without TAK1-knockdown were also examined after irradiation to elucidate the molecular mechanisms involved. After X-ray irradiation, cell death estimated by the colony formation assay increased in the TAK1-knockdown cells. Apoptosis induction, determined by caspase-3 cleavage, suggested that the increased radiosensitivity of the TAK1-knockdown cells could be partially explained by the induction of apoptosis. However, cell cycle analysis revealed that the percentage of irradiated cells in the G(2)/M-phase decreased, and those in the S- and SubG(1)-phases increased due to TAK1 depletion, suggesting that the loss of cell cycle checkpoint regulation may also be involved in the observed increased radiosensitivity. Interestingly, significant differences in the induction of NF-κB, p38 MAPK and ERK phosphorylation, the major downstream molecules of TAK1, were not observed in TAK1 knockdown cells compared to their parental control cells after irradiation. Instead, global gene expression analysis revealed differentially expressed genes after irradiation that bioinformatics analysis suggested are associated with cell cycle regulatory networks. In particular, CDKN1A (coding p21(WAF1)), which plays a central role in the identified network, was up-regulated in control cells but not in TAK1 knockdown cells after X-ray irradiation. Si-RNA knockdown of p21 decreased the percentage of cells in the G(2)/M phase and increased the percentage of cells in the S- and SubG(1)-phases after X-ray irradiation in a similar manner as TAK-1 knockdown. Taken together, these findings suggest that the role of TAK1 in cell death, cell cycle regulation and apoptosis after X irradiation is independent of NF-κB, p38 MAPK, and ERK phosphorylation, and dependent, in part, on p21 induction.     

p38MAPK-regulated induction of p62 and NBR1 after photodynamic therapy promotes autophagic clearance of ubiquitin aggregates and reduces reactive oxygen species levels by supporting Nrf2–antioxidant signaling

Emerging evidence indicates that oxidative stress instigates the formation of ubiquitin (Ub) aggregates, substrates of autophagy, through a process requiring the ubiquitin binding adaptors p62/SQSTM1 and NBR1. Here, we have investigated the role of p62 and NBR1 in cell survival after hypericin-mediated photodynamic therapy (Hyp-PDT), a procedure known to incite robust reactive oxygen species (ROS)-based endoplasmic reticulum stress and autophagy pathways. We found that Hyp-PDT stimulated the formation of p62- and NBR1-associated Ub aggregates in normal and cancer cells, which were ultimately removed by autophagy, through a mechanism partially regulated by p38^MAPK. In line with this, genetic or pharmacological p38^MAPK inhibition reduced p62 and NBR1 levels and aggregate formation and impaired Nrf2 activation, thus increasing photo-oxidative stress and cell death. p62-deficient cells, or cells lacking p62 and with reduced levels of NBR1 (through siRNA knockdown), also displayed reduced aggregate formation but exhibited attenuated ROS levels, reduced caspase activation, and improved survival after Hyp-PDT. The increased resistance to photo-oxidative stress exhibited by cells lacking p62 and/or NBR1 was overruled by the inhibition of p38^MAPK, which restored cytotoxic ROS levels, thus indicating the relevance of this signal in the control of cell viability. Taken together these findings provide evidence that in photodynamically treated cells a p38^MAPK-regulated pathway coordinates the p62/NBR1-mediated clearance of cytosolic aggregates and mitigates PDT-induced proteotoxicity. They also reveal that a functional p38^MAPK–Nrf2 signal is required to keep ROS levels in check and protect against PDT-induced proteotoxicity, independent of aggregate formation.