Expression Of Catalytic Subunit Research Articles

Differential expression of catalytic subunits of NADPH oxidase in human placenta from gestational diabetes

Differential expression of catalytic subunits of NADPH oxidase in human placenta from gestational diabetes

Activation of NRF2 by p62 and proteasome reduction in sphere-forming breast carcinoma cells.

Cancer stem cells (CSCs) express high levels of drug efflux transporters and antioxidant genes, and are therefore believed to be responsible for cancer recurrence following chemo/radiotherapy intervention. In this study, we investigated the role of NF-E2-related factor 2 (NRF2), a master regulator of antioxidant gene expression, in the growth and stress resistance of CSC-enriched mammosphere. The MCF7 mammospheres expressed significantly higher levels of the NRF2 protein and target gene expression compared to the monolayer. As underlying mechanisms, we observed that proteolytic activity and expression of the proteasome catalytic subunits were decreased in the mammospheres. Additionally, mammospheres retained a high level of p62 and the silencing of p62 was observed to attenuate NRF2 activation. NRF2 increase was confirmed in sphere-cultures of the colon and ovarian cancer cells. The functional implication of NRF2 was demonstrated in NRF2-knockdown mammospheres. NRF2-silenced mammospheres demonstrated increased cell death and retarded sphere growth as a result of target gene repression. Moreover, unlike the control mammospheres, NRF2-knockdown mammospheres did not develop anticancer drug resistance. Collectively, these results indicated that altered proteasome function and p62 expression caused NRF2 activation in CSC-enriched mammospheres. In addition, NRF2 appeared to play a role in CSC survival and anticancer drug resistance.

Immunomodulation of Selective Naive T Cell Functions by p110δ Inactivation Improves the Outcome of Mismatched Cell Transplantation

SummaryAllogeneic hematopoietic stem cell transplantation (HSCT) can treat certain hematologic malignancies due to the graft versus leukemia (GvL) effect but is complicated by graft versus host disease (GvHD). Expression of the p110δ catalytic subunit of the phosphoinositide 3-kinase pathway is restricted to leukocytes, where it regulates proliferation, migration, and cytokine production. Here, in a mouse model of fully mismatched hematopoietic cell transplantation (HCT), we show that genetic inactivation of p110δ in T cells leads to milder GvHD, whereas GvL is preserved. Inactivation of p110δ in human lymphocytes reduced T cell allorecognition. We demonstrate that both allostimulation and granzyme B expression were dependent on p110δ in naive T cells, which are the main mediators of GvHD, whereas memory T cells were unaffected. Strikingly, p110δ is not mandatory for either naive or memory T cells to mediate GvL. Therefore, immunomodulation of selective naive T cell functions by p110δ inactivation improves the outcome of allogeneic HSCT.

Dose-Dependent AMPK-Dependent and Independent Mechanisms of Berberine and Metformin Inhibition of mTORC1, ERK, DNA Synthesis and Proliferation in Pancreatic Cancer Cells.

Natural products represent a rich reservoir of potential small chemical molecules exhibiting anti-proliferative and chemopreventive properties. Here, we show that treatment of pancreatic ductal adenocarcinoma (PDAC) cells (PANC-1, MiaPaCa-2) with the isoquinoline alkaloid berberine (0.3–6 µM) inhibited DNA synthesis and proliferation of these cells and delay the progression of their cell cycle in G1. Berberine treatment also reduced (by 70%) the growth of MiaPaCa-2 cell growth when implanted into the flanks of nu/nu mice. Mechanistic studies revealed that berberine decreased mitochondrial membrane potential and intracellular ATP levels and induced potent AMPK activation, as shown by phosphorylation of AMPK α subunit at Thr-172 and acetyl-CoA carboxylase (ACC) at Ser79. Furthermore, berberine dose-dependently inhibited mTORC1 (phosphorylation of S6K at Thr389 and S6 at Ser240/244) and ERK activation in PDAC cells stimulated by insulin and neurotensin or fetal bovine serum. Knockdown of α1 and α2 catalytic subunit expression of AMPK reversed the inhibitory effect produced by treatment with low concentrations of berberine on mTORC1, ERK and DNA synthesis in PDAC cells. However, at higher concentrations, berberine inhibited mitogenic signaling (mTORC1 and ERK) and DNA synthesis through an AMPK-independent mechanism. Similar results were obtained with metformin used at doses that induced either modest or pronounced reductions in intracellular ATP levels, which were virtually identical to the decreases in ATP levels obtained in response to berberine. We propose that berberine and metformin inhibit mitogenic signaling in PDAC cells through dose-dependent AMPK-dependent and independent pathways.

PKA is required for the modulation of spinal nociceptive information related to ephrinB–EphB signaling in mice

EphB receptors and their ephrinB ligands are implicated in modulating of spinal nociceptive information processing. Here, we investigated whether protein kinase A (PKA), acts as a downstream effector, participates in the modulation spinal nociceptive information related to ephrinB–EphB signaling. Intrathecal injection of ephrinB2-Fc caused thermal hyperalgesia and mechanical allodynia, which were accompanied by increased expression of spinal PKA catalytic subunit (PKAca) and phosphorylated cAMP-response element-binding protein (p-CREB). Pre-treatment with H89, a PKA inhibitor, prevented the activation of CREB by ephrinB2-Fc. Inhibition of spinal PKA signaling prevented and reversed pain behaviors induced by the intrathecal injection of ephrinB2-Fc. Furthermore, blockade of the EphB receptors by intrathecal injection of EphB2-Fc reduced formalin-induced inflammatory, chronic constrictive injury (CCI)-induced neuropathic, and tibia bone cavity tumor cell implantation (TCI)-induced bone cancer pain behaviors, which were accompanied by decreased expression of spinal PKAca and p-CREB. Overall, these results confirmed the important involvement of PKA in the modulation of spinal nociceptive information related to ephrinBs–EphBs signaling. This finding may have important implications for exploring the roles and mechanisms of ephrinB–EphB signaling in physiologic and pathologic pain.

P10 - The role of hypercholesterolemic diet and vitamin E on Nrf2 pathway, endoplasmic reticulum stress and proteasome activity

Hypercholesterolemia is the major risk factor for the development of atherosclerosis and vitamin E is suggested to have a preventive role in this process (1), although the mechanism of action still remains unclear.The ubiquitin-proteasome system (UPS) may in?uence atherosclerosis by affecting disease-relevant cellular processes such as apoptosis, proliferation, and differentiation, or by affecting cellular stress responses and/or adaptive phenomena, such as ER stress, in?ammation, and redox homeostasis (2). NF-E2-related factor 2 (Nrf2) is a transcription factor that controls the expression of phase II detoxi?cation and antioxidant genes. Nrf2 signaling has additionally been shown to upregulate the expression of the proteasome catalytic subunits (3). In the present study, we investigated the role of Nrf2 pathway on oxidative and ER stress conditions induced by cholesterol diet and the effects of vitamin E on related signaling pathways in in vivo model of atherosclerosis. All experimental procedures were approved by the Marmara University Ethics Committee. Twenty-one male albino rabbits (23 months old) were assigned randomly to four groups fed for 8 weeks: (i) vitamin E deficient diet, (ii) vitamin E deficient diet containing 2% cholesterol, and (iii) vitamin E deficient diet containing 2% cholesterol with daily intramuscular injections of vitamin E (50mg/kg), (iv) vitamin E deficient diet with daily intramuscular injections of vitamin E (50mg/kg).In order to elucidate in vivo role of oxidative stress and ER stress in cardiovascular system of hypercholesterolemic rabbits, we investigated serum levels of cholesterol, MDA and vitamin E and Nrf2, GST-1, GRP78, GRP94, PERK, IRE1 protein levels and the proteasomal activity in aortic tissues will be discussed.

Abstract 542: Regulation of the telomere healing process by the lncRNA TERRA

Abstract Telomere length is regulated by epigenetic marks that modulate, among other things, the expression of the telomerase catalytic subunit. Telomeres and sub-telomeric regions are enriched in histone marks associated to constitutive heterochromatin. The marks before mentioned are essential for the maintenance of telomere integrity and therefore for genomic stability, but there is another kind of regulation that depends on ncRNAs. This is the case of the lncRNA Telomere repeat-containing RNA (TERRA), an element required for telomeric integrity, considered to hinder chromosomal instability where anaphase bridges, sister chromatid fusions and multi-telomeric regions can take place. This instability leads to chromosomal aberrations that could produce a malignant cell lineage, however, in order for this event to take place, a telomere healing process must occur so that the ribonucleoproteic complex of the telomere can be stabilized once more. For this reason it is important to study the role that the lncRNA TERRA plays in telomere stabilization and how its malfunctioning can bring forth an carcinogenic process. The telomeric regions of interest were analyzed using the data base of the University of California in Santa Cruz (UCSC). We chose the short arm of chromosome 5, where telomerase is encoded, and looked for elements associated to promoter regions such as the presence of the nuclear factor CTCF, Polymerase II, histone marks related with promoters (H3K4me3 and H3K4me1), potential transcription start sites (TSS) and sequences with enhancer potential. We worked with two cell lines of the same cell lineage K562 and SC, in order to have a leukemic and a non-transformed cell model. In order to enrich the amount of TERRA after RNA extraction, we synthesized cDNA using both dT primers and telomere repeat-containing oligonucleotides. The cDNA was used to evaluate the total amount of TERRA in both cell lines using the expression of the ncRNAs U6, HOTAIR and H19 as an amplification reference. We demonstrated that the short arm of chromosome 5 does codify for TERRA, and we verified that only the DNA strand that encodes TERRA was transcribed. Furthermore, we confirmed that the predicted TSS was functional. qPCR showed that there are changes in TERRA expression that take place in accordance with population doubling events. This was observed in the analyzed telomeres of both cell lines used. These results could be related with the natural shortening of telomeres that happens in non-transformed cells, but since such a process is absent in leukemic cells, further investigation is required to answer this query. Citation Format: Diego A. Oliva-Rico, Rodrigo Gonzalez-Barrios, Eunice Fabian-Morales, Luis A. Herrera. Regulation of the telomere healing process by the lncRNA TERRA. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 542. doi:10.1158/1538-7445.AM2014-542

Abstract 2399: DNA-PK is activated by microtubule-targeting agents; mechanistic studies using isogenic wild-type and DNA-PK knockout cells

Abstract DNA-dependent protein kinase (DNA-PK) is a serine-threonine kinase essential for the double-strand break repair pathway non-homologous end-joining. The DNA-PK inhibitor NU7441 has been shown to sensitise cancer cells to ionising radiation and DNA-damaging agents, both in vitro and in vivo. Recent studies show alternative roles of DNA-PK, including localisation and regulation at the centrosome during mitosis. We therefore hypothesised that targeting DNA-PK would sensitise cells to clinically-used microtubule-targeting agents. We recently discovered that DNA-PK inhibitors sensitise cells to vincristine and docetaxel, and that DNA-PK deficient MO59J glioblastoma cells were 2-fold more sensitive to docetaxel than DNA-PK proficient MO59J-Fus1 cells (Mould E, Proc Ann Meet AACR 2013; 54: #3329). Here, we studied an isogenic panel of DNA-PK proficient and deficient cells to further understand the role of DNA-PK in the cellular response to microtubule-targeting agents. We used the X-MAN isogenic cell line panel of HCT116 cells (Horizon Discovery Ltd) with varying DNA-PK catalytic subunit expression levels (parental DNA-PK +/+, DNA-PK +/-, DNA-PK -/- and DNA-PK -/- cells with PRKDC cDNA re-expression (DNA-PK RE). Since ionising radiation (IR) activates DNA-PK, we used IR-induced DNA-PK activity as a positive control in studies with these cell lines. Growth inhibition and clonogenic survival assays showed the DNA-PK -/- cells were at least 4-fold more radiosensitive than the parental DNA-PK +/+ HCT116 cell line. DNA-PK +/- cells displayed a similar response to IR to the DNA-PK +/+ cells. Western blotting demonstrated that DNA-PK RE cells expressed DNA-PK to a level similar to the DNA-PK +/- cells, and the DNA-PK RE were 2.6-fold more resistant to IR compared to the DNA-PK -/- cells. Cells lacking DNA-PKcs therefore display the expected radiosensitivity. We then analysed the effect of microtubule-targeting agents on this cell line panel. DNA-PK -/- cells were 1.5-fold and 1.7-fold more sensitive to vincristine and docetaxel, respectively, than DNA-PK +/+ cells (growth inhibition assay), which is similar to the level of chemo-sensitisation by the DNA-PK inhibitor, NU7441, in a range of cell lines treated with vincristine or docetaxel. Vincristine treatment (24hrs) resulted in activation of DNA-PK (autophosphorylation at ser 2056) in DNA-PK +/+, DNA-PK +/- and DNA-PK RE cells. These data confirm our previous findings and demonstrate in an isogenic model that DNA-PK plays a role in response of cancer cells to microtubule-targeting agents. Ongoing studies with this cell line panel will investigate changes in expression of DNA-PK downstream targets and other DNA-damage-activated kinases in response to both DNA-damaging and microtubule-targeting agents, complemented with microscopy studies to investigate changes in microtubule dynamics and mitotic spindle formation. Citation Format: Emily V.A. Mould, David R. Newell, Elaine Willmore. DNA-PK is activated by microtubule-targeting agents; mechanistic studies using isogenic wild-type and DNA-PK knockout cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2399. doi:10.1158/1538-7445.AM2014-2399

Puerarin induces the upregulation of glutathione levels and nuclear translocation of Nrf2 through PI3K/Akt/GSK-3β signaling events in PC12 cells exposed to lead

Oxidative stress is thought to be involved in lead-induced toxicity, especially affecting the brain. We reported previously that puerarin possesses antioxidative properties in the nervous system. Therefore, the aim of the present study was to test the hypothesis that puerarin inhibits lead acetate-induced oxidative stress in PC12 cells by interrupting phosphatidylinositol-3 kinase (PI3K)/Akt signaling through increasing glutathione (GSH) synthesis. Our results showed that puerarin attenuates oxidative stress in a concentration-dependent manner in PC12 cells exposed to lead acetate demonstrated by scavenging reactive oxygen species (ROS) and reducing lipid peroxidation (LPO). Treatment with puerarin significantly up-regulates glutamate cysteine ligase catalytic subunit (GCLc) expression both at its mRNA and protein levels, but not glutamate cysteine ligase modifier (GCLm) subunit, accompanying the elevation of cellular glutathione level. The increased nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) was not because of increased transcription of Nrf2 as Nrf2 transcript levels did not change after puerarin treatment. The effects of puerarin could be partially blocked by pharmacologic inhibition of PI3K and the glycogen synthase kinase 3β (GSK-3β) pathways with LY294002 and LiCl, respectively. On the other hand, puerarin treatment promoted Akt and GSK-3β phosphorylation in PC12 cells exposed to lead acetate. Moreover, puerarin failed to modulate the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), p-c-Jun N-terminal kinases (JNK), and p-p38 mitogen-activated protein kinase (MAPK) demonstrating some specificity for its action on the PI3K/GSK-3β pathway. These findings suggest that puerarin as a phytoestrogen might be an attractive agent for prevention and treatment of chronic diseases related to lead neurotoxicity.

Subtelomeric demethylation deregulated hTERT expression, telomerase activity, and telomere length in four nasopharyngeal carcinoma cell lines.

Global DNA hypomethylation, in particular that of the gene promoter sequence in gene hypermethylation, is a well-known characteristic of human cancer. Subtelomeres are enriched CpG islands; methylation is believed to be a potential epigenetic regulator. However, regulation on the telomere length remains largely unknown. To demonstrate this correlation, four nasopharyngeal carcinoma cell lines (CNE, CNE1, CNE2, 5-8F) were treated for 72 hours with 0, 1, or 2.5 μM of the demethylating agent 5-aza-2'-deoxycytidine (5-aza-dC). Subtelomeric (D4Z4) level methylation was evaluated with a bisulfite assay, the human telomerase catalytic subunit (hTERT) expression was assayed by reverse transcription-polymerase chain reaction, the telomerase activity was detected using a telomeric repeat amplification protocol assay, and the telomere length was measured by Southern blot terminal restriction fragment analysis. There was significant demethylation following 5-aza-dC treatment, and a strongly repressed hTERT expression decreased the telomerase activity and remarkably shortened telomeres. Thus, partial subtelomeric methylation does not repress hTERT expression; conversely, demethylation may downregulate hTERT expression and shorten telomeres.

Adverse prognostic and predictive significance of low DNA-dependent protein kinase catalytic subunit (DNA-PKcs) expression in early-stage breast cancers.

DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a serine threonine kinase belonging to the PIKK family (phosphoinositide 3-kinase-like-family of protein kinase), is a critical component of the non-homologous end-joining pathway required for the repair of DNA double-strand breaks. DNA-PKcs may be involved in breast cancer pathogenesis. We evaluated clinicopathological significance of DNA-PKcs protein expression in 1,161 tumours and DNA-PKcs mRNA expression in 1,950 tumours. We correlated DNA-PKcs to markers of aggressive phenotypes, DNA repair, apoptosis, cell cycle regulation and survival. Low DNA-PKcs protein expression was associated with higher tumour grade, higher mitotic index, tumour de-differentiation and tumour type (ps < 0.05). The absence of BRCA1, low XRCC1, low SMUG1, low APE1 and low Polβ was also more likely in low DNA-PKcs expressing tumours (ps < 0.05). Low DNA-PKcs protein expression was significantly associated with worse breast cancer-specific survival (BCSS) in univariate and multivariate analysis (ps < 0.01). At the mRNA level, similarly, low DNA-PKcs was associated with poor BCSS. In patients with ER-positive tumours who received endocrine therapy, low DNA-PKcs (protein and mRNA) was associated with poor survival. In ER-negative patients, low DNA-PKcs mRNA remains significantly associated with adverse outcome. Our study suggests that low DNA-PKcs expression may have prognostic and predictive significance in breast cancers.

OP0131 Upregulation of Immunoproteasome Subunits PSMB8 and PSMB9 in Myositis Indicates Active Inflammation with Involvement of Antigen Presenting Cells, CD8+ T-Cells and IFN Gamma

BackgroundIn idiopathic inflammatory myopathies (IIM) infiltration of immune cells into muscle and upregulation of MHC-I expression implies increased antigen presentation and involvement of the proteasome system.ObjectivesTo decipher the role of...

Targeting the Warburg effect with a novel glucose transporter inhibitor to overcome gemcitabine resistance in pancreatic cancer cells.

Gemcitabine resistance remains a significant clinical challenge. Here, we used a novel glucose transporter (Glut) inhibitor, CG-5, as a proof-of-concept compound to investigate the therapeutic utility of targeting the Warburg effect to overcome gemcitabine resistance in pancreatic cancer. The effects of gemcitabine and/or CG-5 on viability, survival, glucose uptake and DNA damage were evaluated in gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer cell lines. Mechanistic studies were conducted to determine the molecular basis of gemcitabine resistance and the mechanism of CG-5-induced sensitization to gemcitabine. The effects of CG-5 on gemcitabine sensitivity were investigated in a xenograft tumor model of gemcitabine-resistant pancreatic cancer. In contrast to gemcitabine-sensitive pancreatic cancer cells, the resistant Panc-1 and Panc-1(GemR) cells responded to gemcitabine by increasing the expression of ribonucleotide reductase M2 catalytic subunit (RRM2) through E2F1-mediated transcriptional activation. Acting as a pan-Glut inhibitor, CG-5 abrogated this gemcitabine-induced upregulation of RRM2 through decreased E2F1 expression, thereby enhancing gemcitabine-induced DNA damage and inhibition of cell survival. This CG-5-induced inhibition of E2F1 expression was mediated by the induction of a previously unreported E2F1-targeted microRNA, miR-520f. The addition of oral CG-5 to gemcitabine therapy caused greater suppression of Panc-1(GemR) xenograft tumor growth in vivo than either drug alone. Glut inhibition may be an effective strategy to enhance gemcitabine activity for the treatment of pancreatic cancer.

Allo-antigen stimulated CD8+ T-cells suppress NF-κB and Ets-1 DNA binding activity, and inhibit phosphorylated NF-κB p65 nuclear localization in CD4+ T-cells.

CD8+ T-cells of asymptomatic HIV-1 carriers (AC) suppress human immunodeficiency virus type 1 (HIV-1) replication in a class I major histocompatibility complex (MHC-I)-restricted and -unrestricted manner. In order to investigate the mechanism of MHC-I-unrestricted CD8+ T-cell-mediated HIV-1 suppression, we previously established allo-antigen stimulated CD8+T-cells from HIV-1-uninfected donors. These allo-antigen stimulated CD8+ T-cells suppressed HIV-1 replication in acutely infected autologous CD4+ T-cells when directly co-cultured. To elucidate the mechanism of HIV-1 replication suppression, we analyzed DNA-binding activity and phosphorylation of transcriptional factors associated with HIV-1 replication by electrophoresis mobility shift assay and Western blotting. When CD4+ T-cells were cultured with allo-antigen stimulated CD8+ T-cells, the reduction of NF-κB and Ets-1 DNA-binding activity was observed. Nuclear localization of NF-κB p65 and Ets-1 was suppressed in CD4+ T-cells. Although NF-κB p65 and Ets-1 are known to be regulated by protein kinase A (PKA), no difference was observed in the expression and phosphorylation of the PKA catalytic subunit in CD4+ T-cells cultured with PHA-treated CD8+ T-cells or allo-antigen stimulated CD8+ T-cells. Cyclic AMP is also known to enter through gap junctions, but the suppression of HIV-1 replication mediated by allo-antigen stimulated CD8+ T-cells was not affected by the gap junction inhibitor. The nuclear transport of phosphorylated NF-κB p65 (Ser276) was inhibited only in CD4+ T-cells cultured with allo-antigen stimulated CD8+ T-cells. Our results indicate that allo-antigen stimulated CD8+ T-cells suppress the transcriptional activity of NF-κB p65 or Ets-1 in an antigen-nonspecific manner, and inhibit the nuclear transport of phosphorylated NF-κB p65 (Ser276).

ZEB1 sensitizes lung adenocarcinoma to metastasis suppression by PI3K antagonism.

Epithelial tumor cells that have undergone epithelial-to-mesenchymal transition (EMT) are typically prone to metastasis and drug resistance and contribute to a poor clinical outcome. The transcription factor ZEB1 is a known driver of EMT, and mediators of ZEB1 represent potential therapeutic targets for metastasis suppression. Here, we have shown that phosphatidylinositol 3-kinase-targeted (PI3K-targeted) therapy suppresses metastasis in a mouse model of Kras/Tp53-mutant lung adenocarcinoma that develops metastatic disease due to high expression of ZEB1. In lung adenocarcinoma cells from Kras/Tp53-mutant animals and human lung cancer cell lines, ZEB1 activated PI3K by derepressing miR-200 targets, including amphiregulin (AREG), betacellulin (BTC), and the transcription factor GATA6, which stimulated an EGFR/ERBB2 autocrine loop. Additionally, ZEB1-dependent derepression of the miR-200 and miR-183 target friend of GATA 2 (FOG2) enhanced GATA3-induced expression of the p110α catalytic subunit of PI3K. Knockdown of FOG2, p110α, and RHEB ameliorated invasive and metastatic propensities of tumor cells. Surprisingly, FOG2 was not required for mesenchymal differentiation, suggesting that mesenchymal differentiation and invasion are distinct and separable processes. Together, these results indicate that ZEB1 sensitizes lung adenocarcinoma cells to metastasis suppression by PI3K-targeted therapy and suggest that treatments to selectively modify the metastatic behavior of mesenchymal tumor cells are feasible and may be of clinical value.

The adjuvant component α-tocopherol triggers via modulation of Nrf2 the expression and turnover of hypocretin in vitro and its implication to the development of narcolepsy

BackgroundAfter the H1N1 swine flu vaccination campaign an increased number of narcolepsy cases in children and adolescents was observed in Scandinavian and later in further European countries that correlated with the vaccination by an AS03-adjuvanted influenza vaccine (Pandemrix). Narcolepsy is a chronic sleep disorder characterized by the loss of hypocretin in the cerebrospinal fluid due to selective destruction of hypocretin-producing neurons in the perifornical hypothalamus. In >99% of the cases narcolepsy is associated with the HLA-subtype DQB1*602 giving the link to an autoimmune process. In contrast to other squalene-based adjuvants, for which no association with narcolepsy was reported so far, ASO3 contains in addition α-tocopherol. It could be observed recently that α-tocopherol activates the transcription factor Nrf2. Nrf2 triggers the expression of cytoprotective genes, i.e. the catalytic active subunits of the constitutive proteasome, by binding to the antioxidant response element (ARE). It was hypothesized that α-tocopherol via activation of Nrf2 affects expression and turnover of hypocretin, leading to an increased amount of hypocretinα-specific fragments that bind to DQB1*602. Resultsα-Tocopherol activates Nrf2 in neuronal cells in vitro. Promoter analysis revealed an ARE sequence in the hypocretin promoter. Indeed, α-tocopherol increases by activation of Nrf2 the expression of hypocretin. In parallel, α-tocopherol -dependent induction of Nrf2 augments expression of catalytic subunits of the proteasome leading to increased degradation of hypocretin. Moreover, elevated activation of Nrf2 is associated with a decreased activity of NF-κB that results in an increased sensitivity to apoptotic stimuli. ConclusionIn case of a genetic predisposition (DQB1*602) α-tocopherol could confer to development of narcolepsy by activation of Nrf2 that finally leads to an elevated formation of longer hypocretin-derived fragments that can be presented by HLA-subtype DQB1*602. These cells are recognized by the immune system and due to their increased sensitivity to apoptotic stimuli they can be destroyed, finally leading to a lack of hypocretin.

Protein phosphatase 2A dysfunction in Alzheimer’s disease

Protein phosphatase 2A (PP2A) is a large family of enzymes that account for the majority of brain Ser/Thr phosphatase activity. While PP2A enzymes collectively modulate most cellular processes, sophisticated regulatory mechanisms are ultimately responsible for ensuring isoform-specific substrate specificity. Of particular interest to the Alzheimer’s disease (AD) field, alterations in PP2A regulators and PP2A catalytic activity, subunit expression, methylation and/or phosphorylation, have been reported in AD-affected brain regions. “PP2A” dysfunction has been linked to tau hyperphosphorylation, amyloidogenesis and synaptic deficits that are pathological hallmarks of this neurodegenerative disorder. Deregulation of PP2A enzymes also affects the activity of many Ser/Thr protein kinases implicated in AD. This review will more specifically discuss the role of the PP2A/Bα holoenzyme and PP2A methylation in AD pathogenesis. The PP2A/Bα isoform binds to tau and is the primary tau phosphatase. Its deregulation correlates with increased tau phosphorylation in vivo and in AD. Disruption of PP2A/Bα-tau protein interactions likely contribute to tau deregulation in AD. Significantly, alterations in one-carbon metabolism that impair PP2A methylation are associated with increased risk for sporadic AD, and enhanced AD-like pathology in animal models. Experimental studies have linked deregulation of PP2A methylation with down-regulation of PP2A/Bα, enhanced phosphorylation of tau and amyloid precursor protein, tau mislocalization, microtubule destabilization and neuritic defects. While it remains unclear what are the primary events that underlie “PP2A” dysfunction in AD, deregulation of PP2A enzymes definitely affects key players in the pathogenic process. As such, there is growing interest in developing PP2A-centric therapies for AD, but this may be a daunting task without a better understanding of the regulation and function of specific PP2A enzymes.

Hemin Protects U937 Cells from Oxidative Stress via Glutathione Synthesis

Although heme oxygenase-1 and glutathione play important roles in the antioxidant defense system, the sharing and/or cross-talking of the HO-1 and GSH system remain poorly understood. The object of this study is to determine whether the glutathione system is involved in the antioxidant function of hemin. Hydrogen peroxide decreased the viability of the human leukemic monocyte lymphoma cell line U937. When these cells were pretreated with hemin before the addition of hydrogen peroxide, cell death was prevented. An inhibitor of heme oxygenase-1 or glutathione biosynthesis significantly abolished this protective effect of hemin. These results suggest that both heme oxygenase-1 and glutathione are involved in the protective effects of hemin against U937 cell death, which was induced by hydrogen peroxide. Hemin induced an increase in glutathione levels following the upregulation of the gene expression and protein levels of glutamate-cysteine ligase catalytic subunit. The inhibitor of heme oxigenase-1 inhibited the upregulation of glutamate-cysteine ligase catalytic subunit expression. These results suggest that hemin induces glutathione synthesis through heme oxygenase-1 activation to protect cells from hydrogen peroxide-induced oxidative stress.

Molecular mechanisms of lipopolysaccharide-mediated inhibition of glutathione synthesis in mice

Endotoxemia correlates with the degree of liver failure and may participate in worsening of liver diseases. Lipopolysaccharide (LPS; synonymous with endotoxin) treatment in mice lowered the hepatic glutathione (GSH) level, which in turn is a variable that determines susceptibility to LPS-induced injury. We previously showed that LPS treatment in mice lowered hepatic expression of the rate-limiting enzyme in GSH synthesis, glutamate–cysteine ligase (GCL). The aim of our current work was to determine the molecular mechanism(s) responsible for these changes. Studies were done using RAW cells (murine macrophages), in vivo LPS-treated mice, and mouse hepatocytes. We found that LPS treatment lowered GCL catalytic and modifier (Gclc and Gclm) subunit expression at the transcriptional level, which was unrelated to alterations in nitric oxide production or induction of NF-κB/p65 subunit. The key mechanism was a decrease in sumoylation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and MafG, which is required for their heterodimerization and subsequent binding and trans-activation of the antioxidant-response element (ARE) present in the promoter region of these genes that is essential for their expression. LPS treatment lowered markedly the expression of ubiquitin-conjugating enzyme 9 (Ubc9), which is required for sumoylation. Similar findings also occurred in liver after in vivo LPS treatment and in LPS-treated mouse hepatocytes. Overexpression of Ubc9 protected against LPS-mediated inhibition of Gclc and Gclm expression in RAW cells and hepatocytes. In conclusion, LPS-mediated lowering of GCL expression in hepatocytes and macrophages is due to lowering of sumoylation of Nrf2 and MafG, leading to reduced heterodimerization, binding, and trans-activation of ARE.

Abstract A136: Proteome analysis reveals candidate genes regulated by BLID, a novel drug-inducible apoptotic target, in breast cancer cells.

Abstract BLID, BH-3 Like motif containing Inducer of cell Death, is a strong prognostic factor in invasive breast cancer (1). Frequent lack of BLID in breast cancer has been associated with triple-negative breast cancer (TNBC), African American ethnicity and younger women. Significant correlations exist between BLID negative breast cancer and declines in overall survival, local relapse-free survival and distant metastasis-free survival. In dose response and time course studies, BLID expression was found to be induced by chemotherapeutic drugs including doxorubicin, 5-fluorouracil and cisplatin in MCF-7 breast cancer cells. In addition, exogenous expression of BLID cDNA nanocomplex led to significant increase in chemosensitivity in SKBr3 (ER-ve/PR-ve) and MDA-MB231 (TNBC) breast cancer cell lines. Here we have investigated the effects of BLID knockdown on protein expression profiles in representative hormone responsive (MCF-7) and TNBC breast cancer cells (MDA-MB231) with a goal to identify a core translational component signifying BLID activity in breast cancer cells. BLID shRNA lentiviral particles were generated using pLKO.1-TRC containing BLID shRNA clone 47 according to the supplier's manual (Sigma-Aldrich). Breast cancer cells were stably transfected with BLID shRNA or scrambled shRNA. The pooled stable clones were tested for BLID expression by western blot analysis. Significant knockdown of BLID protein was achieved in breast cancer cells transfected with BLID shRNA (% inhibition of BLID expression vs. scrambled shRNA: MCF-7, 69%; MDA-MB231, 63%). The BLID proteome analysis was performed using antibody microarrays as we reported earlier (2). We have observed distinct and overlapping BLID-centric protein profiles in MCF-7 and MDA-MB231 cells. Among the top-ranked genes, BLID knockdown correlated with increased expression of PI3-kinase catalytic subunit α and DEK oncogene in MCF-7 cells, and increased expression of myeloid cell leukemia sequence 1 (MCL-1) in MDA-MB231 cells. Remarkably, BLID depletion correlated with decreased expression of tumor protein p73 and cAMP-dependent protein kinase (PKA Type Iα) in both cell lines. Thus, we have identified a working platform of genes signifying BLID expression in breast cancer cells. Validation of the top-ranked genes in various models of breast cancer is ongoing and data will be presented. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A136. Citation Format: Sivaramakrishna Yadavalli, Ofer Eidelman, Meera Srivastava, Usha N. Kasid. Proteome analysis reveals candidate genes regulated by BLID, a novel drug-inducible apoptotic target, in breast cancer cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A136.