PTEN enhances TNF-induced apoptosis through modulation of nuclear factor-kappaB signaling pathway in human glioma cells

Novel strategies to overcome chemoresistance in human glioblastoma

Temozolomide (TMZ) is currently the first-line chemotherapeutic agent for the treatment of glioblastoma multiforme (GBM). However, the inherent heterogeneity of GBM often results in suboptimal outcomes, particularly due to varying degrees of resistance to TMZ. Over the past several decades, O6-methylguanine-DNA methyltransferase (MGMT)-mediated DNA repair pathway has been extensively investigated as a target to overcome TMZ resistance. Nonetheless, the combination of small molecule covalent MGMT inhibitors with TMZ and other chemotherapeutic agents has frequently led to adverse clinical effects. Recently, additional mechanisms contributing to TMZ resistance have been identified, including epidermal growth factor receptor (EGFR) mutations, overactivation of intracellular signalling pathways, energy metabolism reprogramming or survival autophagy, and changes in tumor microenvironment (TME). These findings suggest that novel therapeutic strategies targeting these mechanisms hold promise for overcoming TMZ resistance in GBM patients. In this review, we summarize the latest advancements in understanding the mechanisms underlying intrinsic and acquired TMZ resistance. Additionally, we compile various small-molecule compounds with potential to mitigate chemoresistance in GBM. These mechanism-based compounds may enhance the sensitivity of GBM to TMZ and related chemotherapeutic agents, thereby improving overall survival rates in clinical practice.

A review on potential heterocycles for the treatment of glioblastoma targeting receptor tyrosine kinases

Glioblastoma, the most aggressive form of brain tumor, poses significant challenges in terms of treatment success and patient survival. Current treatment modalities for glioblastoma include radiation therapy, surgical intervention, and chemotherapy. Unfortunately, the median survival rate remains dishearteningly low at 12-15 months. One of the major obstacles in treating glioblastoma is the recurrence of tumors, making chemotherapy the primary approach for secondary glioma patients. However, the efficacy of drugs is hampered by the presence of the blood-brain barrier and multidrug resistance mechanisms. Consequently, considerable research efforts have been directed toward understanding the underlying signaling pathways involved in glioma and developing targeted drugs. To tackle glioma, numerous studies have examined kinase-downstream signaling pathways such as RAS-RAF-MEK-ERK-MPAK. By targeting specific signaling pathways, heterocyclic compounds have demonstrated efficacy in glioma therapeutics. Additionally, key kinases including phosphatidylinositol 3-kinase (PI3K), serine/threonine kinase, cytoplasmic tyrosine kinase (CTK), receptor tyrosine kinase (RTK) and lipid kinase (LK) have been considered for investigation. These pathways play crucial roles in drug effectiveness in glioma treatment. Heterocyclic compounds, encompassing pyrimidine, thiazole, quinazoline, imidazole, indole, acridone, triazine, and other derivatives, have shown promising results in targeting these pathways. As part of this review, we propose exploring novel structures with low toxicity and high potency for glioma treatment. The development of these compounds should strive to overcome multidrug resistance mechanisms and efficiently penetrate the blood-brain barrier. By optimizing the chemical properties and designing compounds with enhanced drug-like characteristics, we can maximize their therapeutic value and minimize adverse effects. Considering the complex nature of glioblastoma, these novel structures should be rigorously tested and evaluated for their efficacy and safety profiles.

Targeting NF-κB signaling cascades of glioblastoma by a natural benzophenone, garcinol, via in vitro and molecular docking approaches

Glioblastoma multiforme (GBM) is regarded as the most aggressive form of brain tumor delineated by high cellular heterogeneity; it is resistant to conventional therapeutic regimens. In this study, the anti-cancer potential of garcinol, a naturally derived benzophenone, was assessed against GBM. During the analysis, we observed a reduction in the viability of rat glioblastoma C6 cells at a concentration of 30 µM of the extract (p < 0.001). Exposure to garcinol also induced nuclear fragmentation and condensation, as evidenced by DAPI-stained photomicrographs of C6 cells. The dissipation of mitochondrial membrane potential in a dose-dependent fashion was linked to the activation of caspases. Furthermore, it was observed that garcinol mediated the inhibition of NF-κB (p < 0.001) and decreased the expression of genes associated with cell survival (Bcl-XL, Bcl-2, and survivin) and proliferation (cyclin D1). Moreover, garcinol showed interaction with NF-κB through some important amino acid residues, such as Pro275, Trp258, Glu225, and Gly259 during molecular docking analysis. Comparative analysis with positive control (temozolomide) was also performed. We found that garcinol induced apoptotic cell death via inhibiting NF-κB activity in C6 cells, thus implicating it as a plausible therapeutic agent for GBM.

Involvement of the tumour necrosis factor receptor system in glioblastoma cell death induced by palbociclib-heptamethine cyanine dye conjugate

Glioblastoma is the most common and aggressive primary brain tumour in adults. The development of anti-brain cancer agents are challenged by the blood-brain barrier and the resistance conferred by the local tumour microenvironment. Heptamethine cyanine dyes (HMCDs) are a class of near-infrared fluorescence compounds that have recently emerged as promising agents for drug delivery. We conjugated palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, to an HMCD, MHI-148, and conducted drug activity analysis on primary patient-derived glioblastoma cell lines. In addition to the expected cytostatic activity, our in vitro studies revealed that palbociclib-MHI-148 conjugate resulted in an almost 100-fold increase in cytotoxicity compared to palbociclib alone. This shift of palbociclib from cytostatic to cytotoxic when conjugated to MHI-148 was due to increased DNA damage, as indicated by an increase in γH2AX foci, followed by an increased expression of key extrinsic apoptosis genes, including TP53, TNFR1, TRAIL, FADD and caspase 8. In addition, we observed a time-dependent increase in the cell surface expression of TNFR1, consistent with an observed increase in the secretion TNFα, followed by TNFR1 endocytosis at 48 h. The treatment of patient GBM cells with the palbociclib-MHI-148 conjugate prevented TNFα-induced NFκB translocation, suggesting conjugate-induced TNFR1 signalling favoured the TNFR1-mediated apoptotic response rather than the pro-inflammatory response pathway. Notably, pharmacological inhibition of endocytosis of TNFR1, and siRNA-knockdown of TNFR1 reversed the palbociclib-MHI-148-induced cell death. These results show a novel susceptibility of glioblastoma cells to TNFR1-dependent apoptosis, dependent on inhibition of canonical NFκB signalling using our previously reported palbociclib-HMCD conjugate. Video Abstract.

Inhibition of PI3K Signaling Intensified the Antileukemic Effects of Pioglitazone: New Insight into the Application of PPARγ Stimulators in Acute Lymphoblastic Leukemia

Over the past two decades, molecular targeted therapy has revolutionized the landscape of cancer treatment due to lower side effects as well as higher anticancer effects. Peroxisome proliferator-activated receptor gamma (PPARγ) is a member of the nuclear hormone receptor which plays a crucial role in cell proliferation and death and the efficacy of PPARγ ligands either as monotherapy or in combination with traditional chemotherapy drugs has been proved by recent studies. In this study, we aimed to investigate the effects of pioglitazone, a well-known PPARγ stimulator, in ALL-derived NALM6 cells by using trypan blue assay, MTT assay, and flow cytometry analysis. Moreover, to investigate the molecular mechanism action of pioglitazone in these cells, we assessed the possible alterations in the expression of some target genes which regulate cell proliferation, apoptosis, and autophagy system. Our result demonstrated that pioglitazone induced a remarkable antileukemic effect on NALM6 cells through a PTEN-mediated manner. Based on the fact that PI3K hyperactivation is one of the main properties of ALL cells, the effects of PI3K inhibition using CAL-101 on pioglitazone-induced cytotoxicity were evaluated by combinatorial experiments. Moreover, the result of cell cycle assay and qRT-PCR demonstrated that pioglitazone-CAL-101 induced antileukemic effect mainly through induction of p21 and p27-mediated G1 arrest. Additionally, our result showed that inhibition of proteasome and autophagy system, two main cellular processes, increased the antileukemic effects of the agents. Taken together, we suggest a novel therapeutic application for PPARγ stimulators as a single agent or in combination with PI3K inhibitors that should be clinically evaluated in ALL patients.

Glioblastoma Mesenchymal Transition and Invasion are Dependent on a NF-κB/BRD2 Chromatin Complex

Glioblastoma (GBM) represents the most aggressive subtype of glioma, noted for its profound invasiveness and molecular heterogeneity. The mesenchymal (MES) transcriptomic subtype is frequently associated with therapy resistance, rapid recurrence, and increased tumor-associated macrophages. Notably, activation of the NF-κB pathway and alterations in the PTEN gene are both associated with this malignant transition. Although PTEN aberrations have been shown to be associated with enhanced NF-κB signaling, the relationships between PTEN, NF-κB and MES transition are poorly understood in GBM. Here, we show that PTEN regulates the chromatin binding of bromodomain and extraterminal (BET) family proteins, BRD2 and BRD4, mediated by p65/RelA localization to the chromatin. By utilizing patient-derived glioblastoma stem cells and CRISPR gene editing of the RELA gene, we demonstrate a crucial role for RelA lysine 310 acetylation in recruiting BET proteins to chromatin for MES gene expression and GBM cell invasion upon PTEN loss. Remarkably, we found that BRD2 is dependent on chromatin associated acetylated RelA for its recruitment to MES gene promoters and their expression. Furthermore, loss of BRD2 results in the loss of MES signature, accompanied by an enrichment of proneural signature and enhanced therapy responsiveness. Finally, we demonstrate that disrupting the NFκB/BRD2 interaction with a brain penetrant BET-BD2 inhibitor reduces mesenchymal gene expression, GBM invasion, and therapy resistance in GBM models. This study uncovers the role of hitherto unexplored PTEN-NF-κB-BRD2 pathway in promoting MES transition and suggests inhibiting this complex with BET-BD2 specific inhibitors as a therapeutic approach to target the MES phenotype in GBM.

DUSP10 upregulation is a poor prognosticator and promotes cell proliferation and migration in glioma

Dual-specificity phosphatase 10 (DUSP10) correlates with inflammation, cytokine secretion, cell proliferation, survival, and apoptosis. However, its role in glioma is unclear. Herein, we sought to examine the expression and the underlying carcinogenic mechanisms of DUSP10 action in glioma. DUSP10 expression in glioma was significantly higher than that in normal brain tissues. High DUSP10 expression indicated adverse clinical outcomes in glioma patients. Increased DUSP10 expression correlated significantly with clinical features in glioma. Univariate Cox analysis showed that high DUSP10 expression was a potential independent marker of poor prognosis in glioma. Furthermore, DUSP10 expression in glioma correlated negatively with its DNA methylation levels. DNA methylation level of DUSP10 also correlated negatively with poor prognosis in glioma. More importantly, DUSP10 expression correlated positively with the infiltration of B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and dendritic cells in glioma. Gene set enrichment analysis (GSEA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis confirmed that DUSP10 participated in signaling pathways involved in focal adhesion, TNF cascade, Th17 cell differentiation, and NF-kappa B cascade. Finally, we uncovered that DUSP10 was dramatically upregulated in glioblastoma (GBM) cells and that the knockdown of DUSP10 inhibited glioma cell proliferation and migration. Our findings suggested that DUSP10 may serve as a potential prognostic biomarker in glioma.

SMAC Mimetic/IAP Inhibitor Birinapant Enhances Radiosensitivity of Glioblastoma Multiforme

Birinapant is a novel SMAC peptidomimetic molecule in clinical development. It suppresses the inhibitor of apoptosis proteins (IAPs) and promotes cytochrome-C/Apaf-1/caspase-9 activation to induce effective apoptosis. Because IAP inhibition has been shown to enhance the sensitivity of cancer cells to radiation, we investigated the role of birinapant in radiosensitization of glioblastoma cells in vitro and in vivo. Two glioblastoma cell lines, U-251 and U-87, were used to analyze radiosensitization in vitro with 7-AAD cell death/apoptosis and clonogenic assays. Subcutaneous flank (U-251 and U-87) and intracranial orthotopic (U-251) xenografts in nude mice were used to evaluate radiosensitization in vivo. TNF-α levels in media and serum were measured using electrochemiluminescence. Radiosensitization in vitro was more prominent for U-251 cells than for U-87 cells. In vivo, in both tumor models, significant tumor growth delay was observed with combination treatment compared to radiation alone. There was a survival benefit with combination treatment in the orthotopic U-251 model. TNF-α levels in media correlated directly with radiation dose in vitro. These findings show that birinapant can enhance the radiosensitivity of glioblastoma cell lines in cell-based assays and tumor models via radiation-induced TNF-α. Further study into the use of birinapant with radiation therapy is warranted.

Diagnostic and Prognostic Value of Long Noncoding RNAs as Potential Novel Biomarkers in Intrahepatic Cholestasis of Pregnancy

Long noncoding RNAs (lncRNAs) are a class of important regulators participating in various pathological processes. Until now, the role of lncRNAs in the occurrence and development of intrahepatic cholestasis of pregnancy (ICP) has rarely been investigated. The data from microarray screening revealed 58 upregulated and 85 downregulated lncRNAs and 47 upregulated and 71 downregulated mRNAs in ICP patients compared to healthy controls. Bioinformatics analysis revealed biological processes focused on lipid metabolism, apoptosis, cell cycle, cell differentiation, and oxidative stress. Furthermore, the expressions of three lncRNAs (ENST00000505175.1, ASO3480, and ENST00000449605.1) chosen for verification were significantly decreased and showed the diagnostic and prognostic value for ICP based on ROC analysis. This is the first study to report the specific role of lncRNAs in ICP, which may be helpful for the diagnosis and prognosis of ICP clinically.

Integrative Bioinformatics Analysis Reveals Potential Target Genes and TNFα Signaling Inhibition by Brazilin in Metastatic Breast Cancer Cells

OBJECTIVE

Metastasis is the most significant cause of morbidity and mortality in breast cancer patients. Previously, a combination of brazilin and doxorubicin has been shown to inhibit metastasis in HER2-positive breast cancer cells. This present study used an integrative bioinformatics approach to identify new targets and the molecular mechanism of brazilin in inhibiting metastasis in breast cancer.

METHODS

Cytotoxicity and mRNA arrays data were retreived from the DTP website, whereas genes that regulate metastatic breast cancer cells were retreived from PubMed with keywords "breast cancer metastasis". Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and Drug association analysis were carried out by using WEB-based GEne SeT AnaLysis Toolkit (WebGestalt). Construction of protein-protein interaction (PPI) network analysis was performed by STRING-DB v11.0 and Cytoscape, respectively. The genetic alterations of the potential therapeutic target genes of brazilin (PB) were analyzed using cBioPortal.

RESULTS

Analysis of cytotoxicity with the public database of COMPARE showed that brazilin exerts almost the same cytotoxicity in the NCI-60 cells panel showing by similar GI50 value, in which the lowest GI50 value was observed in MDA-MB 231, a metastatic breast cancer cells. KEGG enrichment indicated several pathways regulated by brazilin such as TNF signaling pathway, cellular senescence, and pathways in cancer. We found ten drugs that are associated with PB, including protein kinase inhibitors, TNFα inhibitors, enzyme inhibitors, and anti-inflammatory agents.

CONCLUSION

In conclusion, this study identified eight PB, including MMP14, PTGS2, ADAM17, PTEN, CCL2, PIK3CB, MAP3K8, and CXCL3. In addition, brazilin possibly inhibits metastatic breast cancer through inhibition of TNFα signaling. The study results study need to be validated with in vitro and in vivo studies to strengthen scientific evidence of the use of brazilin in breast cancer metastasis inhibition.

PTEN Is Required for The Anti-Epileptic Effects of AMPA Receptor Antagonists in Chronic Epileptic Rats

α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is one of the ligand-gated ion channels for glutamate, which is an important player in the generation and spread of seizures. The efficacy of AMPAR functionality is regulated by the trafficking, synaptic targeting, and phosphorylation. Paradoxically, AMPAR expression and its phosphorylation level are decreased in the epileptic hippocampus. Therefore, the roles of AMPAR in seizure onset and neuronal hyperexcitability in ictogenesis remain to be elucidated. In the present study, we found that AMPAR antagonists (perampanel and GYKI 52466) decreased glutamate ionotropic receptor AMPA type subunit 1 (GRIA1) surface expression in the epileptic rat hippocampus. They also upregulated phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression and restored to basal levels the upregulated phosphoinositide 3-kinase (PI3K)/AKT1 phosphorylations. Dipotassium bisperoxovanadium(pic) dihydrate (BpV(pic), a PTEN inhibitor) co-treatment abolished the anti-epileptic effects of perampanel and GYKI 52466. Therefore, our findings suggest that PTEN may be required for the anti-epileptic effects of AMPAR antagonists.

Notch1 is a prognostic factor that is distinctly activated in the classical and proneural subtype of glioblastoma and that promotes glioma cell survival via the NF-κB(p65) pathway

Glioblastomas (GBMs) are the most prevalent and devastating primary intracranial malignancies and have extensive heterogeneity. Notch1 signaling is a more complex process in the development of numerous cell and tissue types, including gliomagenesis and progression, and is upregulated in glioma-initiating cells. However, the contradictory expression of Notch1 among lower grade gliomas and GBMs confounds our understanding of GBM biology and has made identifying effective therapies difficult. In this study, we validated that Notch1 and NF-κB(p65) are highly expressed in the classical and proneural subtypes of GBM using the data set from The Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA). DAPT and shRNA targeting Notch1 decreased NF-κB(p65) expression, suppressed cell proliferation, and induced apoptosis of GBM cells in vitro and in vivo. Furthermore, we illustrated that the intracellular Notch could bind with NF-κB(p65) in GBM cells. These findings suggest that the cross-talk between Notch1 signaling and NF-κB(p65) could contribute to the proliferation and apoptosis of glioma, and this discovery could help drive the design of more effective therapies in Notch1-targeted clinical trials.

MiRNA-21 has effects to protect kidney injury induced by sepsis

To investigate the miRNA-21 over-expression in the acute kidney injury induced by sepsis, we developed a sepsis induced in vitro model by lip polysaccharide (LPS) and in vovo model by cecal ligation and puncture (CLP) surgery. LPS or CLP surgery induced kidney cell apoptosis increasing. However, the kidney injury indexes of miRNA groups which were transfected with miRNA-21 were significantly suppressed. In further study, the relative proteins expressions were evaluated to explain the miRNA-21 mechanism to improve sepsis induced kidney cell apoptosis. The results were shown that miRNA-21 over-expression had effects to protect kidney cell apoptosis induced by sepsis via PTEN/PI3K/AKT signaling pathway.

NF-κB Signalling in Glioblastoma

Nuclear factor-κB (NF-κB) is a transcription factor regulating a wide array of genes mediating numerous cellular processes such as proliferation, differentiation, motility and survival, to name a few. Aberrant activation of NF-κB is a frequent event in numerous cancers, including glioblastoma, the most common and lethal form of brain tumours of glial cell origin (collectively termed gliomas). Glioblastoma is characterized by high cellular heterogeneity, resistance to therapy and almost inevitable recurrence after surgery and treatment. NF-κB is aberrantly activated in response to a variety of stimuli in glioblastoma, where its activity has been implicated in processes ranging from maintenance of cancer stem-like cells, stimulation of cancer cell invasion, promotion of mesenchymal identity, and resistance to radiotherapy. This review examines the mechanisms of NF-κB activation in glioblastoma, the involvement of NF-κB in several mechanisms underlying glioblastoma propagation, and discusses some of the important questions of future research into the roles of NF-κB in glioblastoma.

Ionotropic glutamate receptor antagonists and cancer therapy: time to think out of the box?

Glutamate has a trophic function in the development of the central nervous system, regulating the proliferation and migration of neuronal progenitors. The resemblance between neuronal embryonic and tumor cells has paved the way for the investigation of the effects of glutamate on tumor cells. Indeed, tumor cells derived from neuronal tissue express ionotropic glutamate receptor (iGluRs) subunits and iGluR antagonists decrease cell proliferation. Likewise, iGluRs subunits are expressed in several peripheral cancer cells and blockade of the N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) ionotropic glutamate receptor subtypes decreases their proliferation and migration. Although these mechanisms are still being investigated, the inhibition of the mitogen-activated protein kinase pathway was shown to play a key role in the antiproliferative activity of iGluR antagonists. Importantly, MK-801, a NMDAR channel blocker, was effective and well tolerated in animal models of melanoma, lung, and breast cancers, suggesting that the blockade of iGluR signaling may represent a new strategy for cancer treatment. In this review, we focus on the significance of NMDA and AMPA receptor expression in tumor cells, as well as possible therapeutic strategies targeting these receptors.

TNF-α induces vascular insulin resistance via positive modulation of PTEN and decreased Akt/eNOS/NO signaling in high fat diet-fed mice

BACKGROUND

High fat diet (HFD) induces insulin resistance in various tissues, including the vasculature. HFD also increases plasma levels of TNF-α, a cytokine that contributes to insulin resistance and vascular dysfunction. Considering that the enzyme phosphatase and tension homologue (PTEN), whose expression is increased by TNF-α, reduces Akt signaling and, consequently, nitric oxide (NO) production, we hypothesized that PTEN contributes to TNF-α-mediated vascular resistance to insulin induced by HFD. Mechanisms underlying PTEN effects were determined.

METHODS

Mesenteric vascular beds were isolated from C57Bl/6J and TNF-α KO mice submitted to control or HFD diet for 18 weeks to assess molecular mechanisms by which TNF-α and PTEN contribute to vascular dysfunction.

RESULTS

Vasodilation in response to insulin was decreased in HFD-fed mice and in ex vivo control arteries incubated with TNF-α. TNF-α receptors deficiency and TNF-α blockade with infliximab abolished the effects of HFD and TNF-α on insulin-induced vasodilation. PTEN vascular expression (total and phosphorylated isoforms) was increased in HFD-fed mice. Treatment with a PTEN inhibitor improved insulin-induced vasodilation in HFD-fed mice. TNF-α receptor deletion restored PTEN expression/activity and Akt/eNOS/NO signaling in HFD-fed mice.

CONCLUSION

TNF-α induces vascular insulin resistance by mechanisms that involve positive modulation of PTEN and inhibition of Akt/eNOS/NO signaling. Our findings highlight TNF-α and PTEN as potential targets to limit insulin resistance and vascular complications associated with obesity-related conditions.

Nuclear factor-κB in glioblastoma: insights into regulators and targeted therapy

Nuclear factor-κB (NF-κB) is a ubiquitous transcription factor that regulates multiple aspects of cancer formation, growth, and treatment response. Glioblastoma (GBM), the most common primary malignant tumor of the central nervous system, is characterized by molecular heterogeneity, resistance to therapy, and high NF-κB activity. In this review, we examine the mechanisms by which oncogenic pathways active in GBM impinge on the NF-κB system, discuss the role of NF-κB signaling in regulating the phenotypic properties that promote GBM and, finally, review the components of the NF-κB pathway that have been targeted for treatment in both preclinical studies and clinical trials. While a direct role for NF-κB in gliomagenesis has not been reported, the importance of this transcription factor in the overall malignant phenotype suggests that more rational and specific targeting of NF-κB-dependent pathways can make a significant contribution to the management of GBM.

Down-regulation of PTEN by HCV core protein through activating nuclear factor-κB

The hepatitis C virus (HCV) core protein is an important causative agent in HCV related hepatocellular carcinoma (HCC). Tumor suppressor gene PTEN appears to act in the liver at the crossroad of processes controlling cell proliferation. In this study we investigated the effect of the HCV core protein on the PTEN pathway in hepatocarcinogenesis. The HCV core was transfected stably into HepG2 cell. The effect of HCV core on cell proliferation and viability were detected by 3-(4, 5)-dimethylthiahiazo-(-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay, clonogenic survival assay and Fluorescence Activating Cell Sorter (FACS) analysis. The expressions of PTEN were detected by real time RT-PCR and/or Western blot analysis, also the mechanism of down-regulation of PTEN was explored by western blot, luciferase assay and RNA interference. We found the HCV core promoted cell proliferation, survival and G2/M phase accumulation. It downregulated PTEN at mRNA and protein level and activated PTEN downstream gene Akt accompanied with NF-κB activation. Furthermore, the inhibition of HCV core by its specific shRNAs decreased the effect of growth promotion and G2/M phase arrest, inhibited the expression of nuclear p65 and increased PTEN expression. The activity of PTEN was restored when treated with NF-κB inhibitor PDTC. By luciferase assay we found that NF-κB inhibited PTEN promoter transcription activity directly in HCV core cells, while PDTC was contrary. Our study suggests that HCV proteins could modulate PTEN by activating NF-κB. Furthermore strategies designed to restore the expression of PTEN may be promising therapies for preventing HCV dependent hepatocarcinogenesis.

Mitoneet mediates TNFα-induced necroptosis promoted by exposure to fructose and ethanol

Fructose and ethanol are metabolized principally in the liver and are both known to contribute to the development of hepatic steatosis that can progress to hepatic steatohepatitis. The present study indentifies a synergistic interaction between fructose and ethanol in promoting hepatocyte sensitivity to TNFα-induced necroptosis. Concurrent exposure to fructose and ethanol induces the overexpression of the CDGSH iron-sulfur domain-containing protein 1 (CISD1 or mitoneet), which is localized to the outer mitochondrial membrane. The increased expression of mitoneet primes the hepatocyte for TNFα-induced cytotoxicity. Treatment with TNFα induces the translocation of a Stat3-Grim-19 complex to the mitochondria, which binds to mitoneet and promotes the rapid release of its 2Fe-2S cluster, causing an accumulation of mitochondrial iron. The dramatic increase of mitochondrial iron provokes a surge in formation of reactive oxygen species, resulting in mitochondrial injury and cell death. Additionally, mitoneet is constitutively expressed at high levels in L929 fibrosarcoma cells and is required for L929 cells to undergo TNFα-induced necroptosis in the presence of caspase inhibition, indicating the importance of mitoneet to the necroptotic form of cell death.

Glutamate signaling in benign and malignant disorders: current status, future perspectives, and therapeutic implications

Glutamate, a nonessential amino acid, is the major excitatory neurotransmitter in the central nervous system. As such, glutamate has been shown to play a role in not only neural processes, such as learning and memory, but also in bioenergetics, biosynthetic and metabolic oncogenic pathways. Glutamate has been the target of intense investigation for its involvement not only in the pathogenesis of benign neurodegenerative diseases (NDDs) such as Parkinson's disease, Alzheimer's disease, schizophrenia, multiple sclerosis, and amyotropic lateral sclerosis (ALS), but also in carcinogenesis and progression of malignant diseases. In addition to its intracellular activities, glutamate in secreted form is a phylogenetically conserved cell signaling molecule. Glutamate binding activates multiple major receptor families including the metabotropic glutamate receptors (mGluRs) and ionotropic glutamate receptors (iGluRs), both of which have been implicated in various signaling pathways in cancer. Inhibition of extracellular glutamate release or glutamate receptor activation via competitive or non-competitive antagonists decreases growth, migration and invasion and induces apoptosis in breast cancer, melanoma, glioma and prostate cancer cells. In this review, we discuss the current state of glutamate signaling research as it relates to benign and malignant diseases. In addition, we provide a synopsis of clinical trials using glutamate antagonists for the treatment of NDD and malignant diseases. We conclude that in addition to its potential role as a metabolic biomarker, glutamate receptors and glutamate-initiated signaling pathways may provide novel therapeutic opportunities for cancer.

Antibodies to gp120 and PD-1 expression on virus-specific CD8+ T cells in protection from simian AIDS

We compared the relative efficacies against simian immunodeficiency virus (SIV) challenge of three vaccine regimens that elicited similar frequencies of SIV-specific CD4(+) and CD8(+) T-cell responses but differed in the level of antibody responses to the gp120 envelope protein. All macaques were primed with DNA plasmids expressing SIV gag, pol, env, and Retanef genes and were boosted with recombinant modified vaccinia Ankara virus (MVA) expressing the same genes, either once (1 × MVA) or twice (2 × MVA), or were boosted once with MVA followed by a single boost with replication-competent adenovirus (Ad) type 5 host range mutant (Ad5 h) expressing SIV gag and nef genes but not Retanef or env (1 × MVA/Ad5). While two of the vaccine regimens (1 × MVA and 1 × MVA/Ad5) protected from high levels of SIV replication only during the acute phase of infection, the 2 × MVA regimen, with the highest anti-SIV gp120 titers, protected during the acute phase and transiently during the chronic phase of infection. Mamu-A*01 macaques of this third group exhibited persistent Gag CD8(+)CM9(+) effector memory T cells with low expression of surface Programmed death-1 (PD-1) receptor and high levels of expression of genes associated with major histocompatibility complex class I (MHC-I) and MHC-II antigen. The fact that control of SIV replication was associated with both high titers of antibodies to the SIV envelope protein and durable effector SIV-specific CD8(+) T cells suggests the hypothesis that the presence of antibodies at the time of challenge may increase innate immune recruiting activity by enhancing antigen uptake and may result in improvement of the quality and potency of secondary SIV-specific CD8(+) T-cell responses.

Nix protein positively regulates NF-κB activation in gliomas

Previous reports indicate that the NIX/BNIP3L gene acts as a pro-apoptotic factor by interacting with BCL2 and BCL-XL, playing an important role in hypoxia-dependent cell death and acting as a tumor suppressor. However, many studies also showed that NIX is linked to a protective role and cell survival in cancer cells. Nuclear factor-κB (NF-κB) can attenuate apoptosis in human cancers in response to chemotherapeutic agents and ionizing radiation. We observed an absence of i-κBα (NF-κB activation inhibitor) expression, but a greater expression of Nix and p-NF-κB proteins in the Nix-wt U251 cells, which was not observed in the Nix-kn cells under hypoxic conditions. Using electrophoretic mobility shift assay (EMSA) and luciferase detection, the activation of NF-κB was detected only in the Nix-wt U251 cells with hypoxia. These data imply that Nix protein might play a role in the positive regulation of the NF-κB pathway. Moreover, 46 cases of glioma also showed high levels of Nix protein expression, which was always accompanied by high p-NF-κB expression. Patients with Nix (+) showed less tissue apoptosis behavior in glioblastoma (GBM), unlike that observed in the Nix-negative patients (-). The same apoptotic tendency was also identified in anaplastic astrocytoma (AA) groups, but not in astrocytoma (AS). On analyzing the Kaplan-Meier curve, better tumor-free survival was observed only in cases of astrocytoma, and not in AA and GBM. Thus, our study indicates that Nix protein might have multiple functions in regulating glioma behaviors. In the low-grade gliomas (astrocytoma) with low expression of NF-κB, the cell death-inducing function that occurs through a Bax mechanism might predominate and act as a tumor suppressor. While in the malignant gliomas (AA and GBM), with higher expression of the NIX gene and with activity of the NF-κB pathway, the oncogene function of Nix was predominant.

Apoptosis and the target genes of microRNA-21

MicroRNA-21 (miR-21) is frequently up-regulated in cancer and the majority of its reported targets are tumor suppressors. Through functional suppression, miR-21 is implicated in practically every walk of oncogenic life: the promotion of cell proliferation, invasion and metastasis, genome instability and mutation, inflammation, replicative immortalization, abnormal metabolism, angiogenesis, and evading apoptosis, immune destruction, and growth suppressors. In particular, miR-21 is strongly involved in apoptosis. In this article, we reviewed the experimentally validated targets of miR-21 and found that two thirds are linked to intrinsic and/or extrinsic pathways of cellular apoptosis. This suggests that miR-21 is an oncogene which plays a key role in resisting programmed cell death in cancer cells and that targeting apoptosis is a viable therapeutic option against cancers expressing miR-21.

AMP-activated protein kinase-α1 as an activating kinase of TGF-β-activated kinase 1 has a key role in inflammatory signals

Although previous studies have proposed plausible mechanisms of the activation of transforming growth factor-β-activated kinase 1 (TAK1) in inflammatory signals, including Toll-like receptors (TLRs), its activating kinase still remains to be unclear. In the present study, we have provided evidences that AMP-activated protein kinase (AMPK)-α1 has a pivotal role for activating TAK1, and thereby regulate NF-κB-dependent gene expressions in inflammatory signaling mediated by TLR4 and TNF-α stimulation. AMPK-α1 specifically interacts with TAK1 and reciprocally regulates their kinase activities. Upon the stimulation of lipopolysaccharide, AMPK-α1-knockdown (AMPK-α1(KD)) or TAK1-knockdown human monocytic THP-1 cells exhibit a dramatic reduction in the TAK1 or AMPK-α1 kinase activity, respectively, and subsequent suppressions of its downstream signaling cascades, which further leads to inhibitions of NF-κB and thereby productions of proinflammatory cytokines, such as TNF-α, IL-1β, and IL-6. Importantly, the microarray analysis of AMPK-α1(KD) cells revealed a dramatic reduction in the NF-κB-dependent genes induced by TLR4 and TNF-α stimulation, and the observation was in significant correlation with the results of quantitative real-time PCR. Moreover, AMPK-α1(KD) cells are highly sensitive to the TNF-α-induced apoptosis, which is accompanied with dramatic reductions in the NF-κB-dependent and anti-apoptotic genes. As a result, our data demonstrate that AMPK-α1 as an activating kinase of TAK1 has a key role in mediating inflammatory signals triggered by TLR4 and TNF-α.

An essential role for the Id1/PI3K/Akt/NFkB/survivin signalling pathway in promoting the proliferation of endothelial progenitor cells in vitro

The enhancement of re-endothelialisation is a critical therapeutic option for repairing injured blood vessels. Endothelial progenitor cells (EPCs) are the major source of cells that participate in endothelium repair and contribute to re-endothelialisation by reducing neointima formation after vascular injury. The over-expression of the inhibitor of differentiation or DNA binding 1 (Id1) significantly improved EPC proliferation. This study aimed to investigate the effects of Id1 on the phosphatidylinositol-3-kinase (PI3K)/Akt/nuclear factor kappa B (NFκB)/survivin signalling pathway and its significance in promoting EPC proliferation in vitro. Spleen-derived EPCs were cultured as previously described. Id1 was presented at low levels in EPCs, and was rapidly up-regulated by stimulation with vascular endothelial growth factor. We demonstrated that transient transfection of Id1 into EPCs activated the PI3K/Akt/NFκB/survivin signalling pathway and promoted EPC proliferation. The proliferation of EPCs was extensively inhibited by silencing of endogenous Id1, and knockdown of Id1 expression led to suppression of PI3K/Akt/NFκB/survivin signalling pathway in EPCs. In addition, blockade by the PI3K-specific inhibitor LY294002, Akt inhibitor, the NFκB inhibitor BAY 11-7082, the survivin inhibitor Curcumin, or the survivin inhibitor YM155 reduced the effects of Id1 transfection. These results suggest that the Id1/PI3K/Akt/NFκB/survivin signalling pathway plays a critical role in EPC proliferation. The Id1/PI3K/Akt/NFκB/survivin signalling pathway may represent a novel therapeutic target in the prevention of restenosis after vascular injury.

Apoptosis and the target genes of microRNA-21

MicroRNA-21 (miR-21) is frequently up-regulated in cancer and the majority of its reported targets are tumor suppressors. Through functional suppression, miR-21 is implicated in practically every walk of oncogenic life: the promotion of cell proliferation, invasion and metastasis, genome instability and mutation, inflammation, replicative immortalization, abnormal metabolism, angiogenesis, and evading apoptosis, immune destruction, and growth suppressors. In particular, miR-21 is strongly involved in apoptosis. In this article, we reviewed the experimentally validated targets of miR-21 and found that two thirds are linked to intrinsic and/or extrinsic pathways of cellular apoptosis. This suggests that miR-21 is an oncogene which plays a key role in resisting programmed cell death in cancer cells and that targeting apoptosis is a viable therapeutic option against cancers expressing miR-21.

PTEN restoration and PIK3CB knockdown synergistically suppress glioblastoma growth in vitro and in xenografts

Glioblastoma is the most frequent and malignant glioma in adults. To develop an effective gene therapy strategy for glioblastoma, we investigated the anti-proliferative effects of phosphatase and tensin homolog (PTEN) restoration and siRNAs specifically targeting PIK3CB and PIK3CA on PTEN-deficient glioblastoma cells in vitro and in subcutaneous xenografts. Restoration of PTEN or knockdown of PIK3CB, but not PIK3CA, in glioblastoma cells markedly down-regulates the phosphorylation level of AKT, inhibits cell proliferation and colony formation, arrests the cell cycle at the G0/G1 stage, and promotes caspase-dependent apoptosis. Combined treatment with PTEN restoration and PIK3CB knockdown shows strong synergy. PTEN restoration or PIK3CB knockdown is also able to efficiently inhibit the growth of human U251 glioblastoma xenografts in nude mice, while tumor growth is entirely suppressed by a combination of the two treatments. In addition, we found that the mRNA levels of inhibitors of apoptosis proteins (IAPs) are reduced in U251 cells by PTEN restoration, suggesting that combined antitumor effects may also be partly attributed to the inhibition of the IAP pathway by PTEN restoration. Collectively, our results demonstrate that PI3 K isoforms play specific roles in tumorigenesis, and that combined treatment of PTEN restoration and PIK3CB siRNA is a promising gene therapy strategy for PTEN-deficient gliomas.

Molecular mechanisms of necrosis in glioblastoma: the role of glutamate excitotoxicity

Glioblastomas continue to rank among the most lethal primary human tumors. Despite treatment with the most rigorous surgical interventions along with the most optimal chemotherapeutic and radiation regimens, the median survival is just 12-15 mo for patients with glioblastoma. Among the histological hallmarks of glioblastoma, necrosis has been demonstrated to be a powerful predictor of poor patient prognosis. Over the years, there have been many advances in our understanding of the molecular mechanisms underlying glioblastoma formation, yet the mechanisms that lead to tumor necrosis remain unclear. One pathway that may lead to necrosis in glioblastoma involves the neurotransmitter, glutamate, which has been shown to accumulate in the peritumoral fluid as a result of decreased cellular uptake by glioblastoma cells. This accumulation leads to subsequent glutamate excitotoxicity and probable necrosis through a massive elevation of intracellular Ca(2+) and reduction in cellular ATP levels. We propose that a pathway involving tumor necrosis factor-alpha (TNFalpha), astrocyte-elevated gene-1 (AEG-1) and nuclear factor-kappaB (NFkappaB) leads to decreased glutamate uptake through coordinated downregulation of the excitatory amino acid transporter 2 (EAAT2), the glutamate transporter responsible for the majority of glutamate uptake in the human brain. In addition, we suggest that AEG-1 signaling, loss of phosphatase and tensin homolog (PTEN), and ionotropic glutamate receptor activity lead to AKT pathway activation, which results in nutrient overconsumption and necrosis. Together, these pathways provide a new perspective on glioblastoma necrosis involving the process of glutamate excitotoxicity. Future research should address the components of these molecular pathways in order to better understand the mechanism of necrosis in glioblastoma and to begin to develop targeted therapies that may improve patient prognosis in the future.

NF-kappaB and STAT3 signaling in glioma: targets for future therapies

Glioblastoma remains the most clinically challenging tumor of the CNS, as evidenced by the dismal change in overall survival over the past 50 years. However, recent advances in high-throughput screening techniques have given rise to a wealth of new information regarding the aberrant signaling pathways that drive the tumor phenotype. Two of these so-called 'oncopathways' are NF-kappaB and JAK/STAT. This review will describe the basic mechanisms of these pathways, explore the relevance of NF-kappaB and JAK/STAT signaling in glioblastoma, and look ahead to experimental compounds that will integrate our knowledge of these pathways into existing therapies.

Survivin: a new target for anti-cancer therapy

Survivin is one of the most cancer-specific proteins identified to date, being upregulated in almost all human tumors. Biologically, survivin has been shown to inhibit apoptosis, enhance proliferation and promote angiogenesis. Because of its upregulation in malignancy and its key role in apoptosis, proliferation and angiogenesis, survivin is currently attracting considerable attention as a new target for anti-cancer therapies. In several animal model systems, downregulation of survivin or inactivation of its function has been shown to inhibit tumor growth. Strategies under investigation to target survivin include antisense oligonucleotides, siRNA, ribozymes, immunotherapy and small molecular weight molecules. The translation of these findings to the clinic is currently ongoing with a number of phase I/II clinical trials targeting survivin in progress. These include use of the antisense oligonucleotide LY2181308, the low molecular weight molecule inhibitor YM155 and survivin-directed autologous cytotoxic T lymphocytes. The optimum use of survivin antagonists in the treatment of cancer is likely to be in combination with conventional cancer therapies.

Present and potential future adjuvant issues in high-grade astrocytic glioma treatment

Despite major advances in the management of malignant gliomas of which glioblastomas represent the ultimate grade of malignancy, they remain characterized by dismal prognoses. Glioblastoma patients have a median survival expectancy of only 14 months on the current standard treatment of surgical resection to the extent feasible, followed by adjuvant radiotherapy plus temozolomide, given concomitantly with and after radiotherapy. Malignant gliomas are associated with such dismal prognoses because glioma cells can actively migrate through the narrow extra-cellular spaces in the brain, often travelling relatively long distances, making them elusive targets for effective surgical management. Clinical and experimental data have demonstrated that invasive malignant glioma cells show a decrease in their proliferation rates and a relative resistance to apoptosis (type I programmed cell death) as compared to the highly cellular centre of the tumor, and this may contribute to their resistance to conventional pro-apoptotic chemotherapy and radiotherapy. Resistance to apoptosis results from changes at the genomic, transcriptional and post-transcriptional level of proteins, protein kinases and their transcriptional factor effectors. The PTEN/ PI3K/Akt/mTOR/NF-kappaB and the Ras/Raf/MEK/ERK signaling cascades play critical roles in the regulation of gene expression and prevention of apoptosis. Components of these pathways are mutated or aberrantly expressed in human cancer, notably glioblastomas. Monoclonal antibodies and low molecular-weight kinase inhibitors of these pathways are the most common classes of agents in targeted cancer treatment. However, most clinical trials of these agents as monotherapies have failed to demonstrate survival benefit. Despite resistance to apoptosis being closely linked to tumorigenesis, tumor cells can still be induced to die by non-apoptotic mechanisms such as necrosis, senescence, autophagy (type II programmed cell death) and mitotic catastrophe. Temozolomide brings significant therapeutic benefits in glioblastoma treatment. Part of temozolomide cytotoxic activity is exerted through pro-autophagic processes and also through the induction of late apoptosis. Autophagy, type II programmed cell death, represents an alternative mechanism to overcome, at least partly, the dramatic resistance of many cancers to pro-apoptotic-related therapies. Another way to potentially overcome apoptosis resistance is to decrease the migration of malignant glioma cells in the brain, which then should restore a level of sensitivity to pro-apoptotic drugs. Recent series of studies have supported the concept that malignant gliomas might be seen as an orchestration of cross-talks between cancer cells, microenvironment, vasculature and cancer stem cells. The present chapter focuses on (i) the major signaling pathways making glioblastomas resistant to apoptosis, (ii) the signaling pathways distinctly activated by pro-autophagic drugs as compared to pro-apoptotic ones, (iii) autophagic cell death as an alternative to combat malignant gliomas, (iv) the major scientific data already obtained by researchers to prove that temozolomide is actually a pro-autophagic and pro-apoptotic drug, (v) the molecular and cellular therapies and local drug delivery which could be used to complement conventional treatments, and a review of some of the currently ongoing clinical trials, (vi) the fact that reducing the levels of malignant glioma cell motility can restore pro-apoptotic drug sensitivity, (vii) the observation that inhibiting the sodium pump activity reduces both glioma cell proliferation and migration, (viii) the brain tumor stem cells as a target to complement conventional treatment.

Nuclear factor-kappaB activation and differential expression of survivin and Bcl-2 in human grade 2-4 astrocytomas

BACKGROUND

Antiapoptotis resulting from hyperactivation of the transcription factor NF-kappaB has been described in several cancer types. It is triggered by the interaction of the tumor necrosis factor (TNF) with its receptors and recruitment of the intermediate factor TNF-receptor associated factor (TRAF) 2. The NF-kappaB transcriptional activity could amplify the expression of antiapoptotic genes. The authors investigated the activity of NF-kappaB, and the mRNA expression of TNFalpha, TNFalpha receptor, TRAF1, TRAF2, and TRAF-associated NF-kappaB activator (TANK), and the antiapoptotic genes Bcl-2, c-IAP 1 and 2, and Survivin in human astrocytic tumors.

METHODS

Eight low-grade astrocytomas (LGA), 10 anaplastic astrocytomas (AAs), 10 glioblastoma multiforme (GBM) samples were used; 4 samples of normal brain tissue were used as controls. The NF-kappaB activation was analyzed by electrophoretic mobility shift assay; TRAF1, TRAF2, TANK/I-TRAF, Bcl-2, c-IAP 1 and 2, and Survivin mRNA expressions were studied using real-time quantitative reverse-transcriptase polymerase chain reaction.

RESULTS

NF-kappaB hyperactivity was detected in tumor samples. mRNA of antiapoptotic genes, particularly BCL-2 and Survivin, was hyperexpressed in gliomas. Interestingly, BCL-2 was hyperexpressed in LGAs, whereas a very high level of Survivin featured high-grade gliomas. The differential expression of antiapoptotic genes yielded a tight clustering of all LGA and nearly all GBM samples in cluster analysis.

CONCLUSIONS

NF-kappaB and factors involved in its intracellular activation were up-regulated in gliomas. NF-kappaB-activated antiapoptotic genes were hyperexpressed in tumor samples, but showed a differential expression with higher levels of Bcl-2 in LGAs and higher levels of Survivin in GBMs.

The tumour suppressor PTEN mediates a negative regulation of the E3 ubiquitin-protein ligase Nedd4

The tumour suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10; a phosphatidylinositol 3-phosphatase) is a multifunctional protein deregulated in many types of cancer. It is suggested that a number of proteins that relate with PTEN functionally or physically have not yet been found. In order to search for PTEN-interacting proteins that might be crucial in the regulation of PTEN, we exploited a proteomics-based approach. PTEN-expressing NIH 3T3 cell lysates were used in affinity chromatography and then analysed by LC–ESI–MS/MS (liquid chromatography–electrospray ionization–tandem MS). A total of 93 proteins were identified. Among the proteins identified, we concentrated on the E3 ubiquitin-protein ligase Nedd4 (neural-precursor-cell-expressed, developmentally down-regulated gene 4), and performed subsequent validation experiments using HeLa cells. Nedd4 inhibited PTEN-induced apoptotic cell death and, conversely, the Nedd4 level was down-regulated by PTEN. The down-regulation effect was diminished by a mutation (C124S) in the catalytic site of PTEN. Nedd4 expression was also decreased by a PI3K (phosphoinositide 3-kinase) inhibitor, LY294002, suggesting that the regulation is dependent on the phosphatase-kinase activity of the PTEN-PI3K/Akt pathway. Semi-quantitative real-time PCR analysis revealed that Nedd4 was transcriptionally regulated by PTEN. Thus our results have important implications regarding the roles of PTEN upon the E3 ubquitin ligase Nedd4 as a negative feedback regulator as well as a substrate.

The sodium pump alpha1 subunit as a potential target to combat apoptosis-resistant glioblastomas

PURPOSE

To review the involvement of the ion transporter Na+/K+-ATPase (NaK) in the migration and proliferation of glioma cells. Preliminary studies indicate that NaK alpha1 subunits seem to be upregulated in a proportion of glioblastomas but not in normal brain tissues.

DESIGN

The present review focuses on (1) the natural resistance of migrating malignant glioma cells to apoptosis, (2) autophagic cell death as an alternative to combat malignant gliomas, (3) the fact that reducing the levels of malignant glioma cell motility can restore proapoptotic drug sensitivity,and (4) on the observation that inhibiting the NaK activity reduces both glioma cell proliferation and migration.

RESULTS

The natural ligands of the NaK are the cardiotonic steroids. A hemisynthetic derivative of 2"-oxovoruscharin (UNBS1450), a novel cardenolide, displays unique structural features, making its binding affinity to NaK alpha subunits (including alpha1) 10 to 100 times higher than that of other cardenolides. UNBS1450 markedly decreases intracellular ATP concentration in glioma cells, disorganizes the actin cytoskeleton, and leads to autophagic cell death in NaK alpha1 over-expressing glioma cells.

CONCLUSIONS

Glioblastoma patients who do not respond to chemotherapy and whose tumors over-express NaK alpha1 subunits could benefit from a treatment using ligands with marked binding affinity for the NaK alpha1 subunit.

Curcumin suppressed anti-apoptotic signals and activated cysteine proteases for apoptosis in human malignant glioblastoma U87MG cells

Glioblastoma is the most malignant human brain tumor that shows poor response to existing therapeutic agents. Search continues for an effective therapy for controlling this deadliest brain tumor. Curcumin (CCM), a polyphenolic compound from Curcuma longa, possesses anti-cancer properties in both in vitro and in vivo. In the present investigation, we evaluated the therapeutic efficacy of CCM against human malignant glioblastoma U87MG cells. Trypan blue dye exclusion test showed decreased viability of U87MG cells with increasing dose of CCM. Wright staining and ApopTag assay, respectively, showed the morphological and biochemical features of apoptosis in U87MG cells treated with 25 microM and 50 microM of CCM for 24 h. Western blotting showed activation of caspase-8, cleavage of Bid to tBid, increase in Bax:Bcl-2 ratio, and release of cytochrome c from mitochondria followed by activation of caspase-9 and caspase-3 for apoptosis. Also, CCM treatments increased cytosolic level of Smac/Diablo to suppress the inhibitor-of-apoptosis proteins and down regulated anti-apoptotic nuclear factor kappa B (NFkappaB), favoring the apoptosis. Increased activities of calpain and caspase-3 cleaved 270 kDa alpha-spectrin at specific sites generating 145 kDa spectrin break down product (SBDP) and 120 kDa SBDP, respectively, leading to apoptosis in U87MG cells. Results show that CCM is an effective therapeutic agent for suppression of anti-apoptotic factors and activation of calpain and caspase proteolytic cascades for apoptosis in human malignant glioblastoma cells.