The pharmacological NFκB inhibitors BAY117082 and MG132 induce cell arrest and apoptosis in leukemia cells through ROS-mitochondria pathway activation

Azilsartan Attenuates 3-Nitropropinoic Acid-Induced Neurotoxicity in Rats: The Role of IĸB/NF-ĸB and KEAP1/Nrf2 Signaling Pathways

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder characterized by motor, psychiatric and cognitive symptoms. Injection of 3-nitropropionic acid (3-NP) is a widely used experimental model for induction of HD. The current study aimed to inspect the potential neuroprotective properties of azilsartan (Azil), an angiotensin II type 1 receptor blocker (ATR1), in 3-NP-induced striatal neurotoxicity in rats. Rats were randomly allocated into five groups and treated for 14 days as follows: group I received normal saline; group II received Azil (10 mg/kg, p.o.); group III received 3-NP (10 mg/kg, i.p); group IV and V received Azil (5 or 10 mg/kg, p.o, respectively) 1 h prior to 3-NP injection. Both doses of Azil markedly attenuated motor and behavioural dysfunction as well as striatal histopathological alterations caused by 3-NP. In addition, Azil balanced striatal neurotransmitters levels as evidenced by the increase of striatal gamma-aminobutyric acid content and the decrease of glutamate content. Azil also amended neuroinflammation and oxidative stress via modulating IĸB/NF-ĸB and KEAP1/Nrf2 downstream signalling pathways, as well as reducing iNOS and COX2 levels. Moreover, Azil demonstrated an anti-apoptotic activity by reducing caspase-3 level and BAX/BCL2 ratio. In conclusion, the present study reveals the neuroprotective potential of Azil in 3-NP-induced behavioural, histopathological and biochemical changes in rats. These findings might be attributed to inhibition of ATR1/NF-κB signalling, modulation of Nrf2/KEAP1 signalling, anti-inflammatory, anti-oxidant and anti-apoptotic properties.

Synthesis of 3-formyl-eudistomin U with anti-proliferation, anti-migration and apoptosis-promoting activities on melanoma cells

The discovery of new lead skeleton against melanoma are urgently needed due to its highly malignant and mortality. Herein, a new molecular entity (EU-5) derived from eudistomin U was synthesized with total yield of 46%, which displayed potent activity against malignant melanoma A375 cells (IC50 = 4.4 µM), no hemolytic toxicity and good physicochemical properties in silico. Colony formation and cell cycle arrest assays revealed that EU-5 suppressed cell proliferation by causing cell cycle arrest at G0/G1 phase. Wound healing and transwell assays suggested that EU-5 could effectively inhibit migration of A375 cells in a dose-dependent manner. Calcein-AM/PI staining, Annexin V-FITC/PI apoptosis detection, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), transcriptomics, quantitative real‑time polymerase chain reaction (qRT‑PCR), spectrometric titration and molecular docking assays indicated that EU-5 could activate p53 signaling pathway and trigger mitochondria-mediated cell apoptosis. Taken together, this study provided a promising lead structure for the design of a new generation of anti-melanoma drugs.

Sulfated carboxymethylcellulose mediated enhancement of Timp3 efficacy synergistically attenuates osteoarthritis through inhibition of NFκB and JNK

Osteoarthritis (OA) is a prevalent degenerative joint condition with no effective disease modifying treatments. In this study, we aimed to address multiple OA hallmarks using a combination of pro-chondrogenic sulfated carboxymethylcellulose (sCMC) and anti-catabolic tissue inhibitor of metalloproteases 3 (Timp3) in relevant disease systems. Firstly, we chemically sulfated carboxymethylcellulose to impart a negative charge and improve the stability of cationic Timp3. The modified sCMC exhibited a molecular weight of 10 kDa and a degree of sulfation of ∼10 %. We further demonstrated that sulfation of CMC confers pro-chondrogenic characteristics. Subsequently, we demonstrated that the combination of sCMC and Timp3 effectively reduced key OA hallmarks, such as matrix degradation, inflammation, and protease expression, in a goat ex vivo OA model compared to individual treatments. We further demonstrated that the anti-OA effect of sCMC and Timp3 is mediated through the suppression of NFκB and JNK activation. To validate the clinical potential and mechanism of action, we conducted experiments on human OA explants. The combination treatment synergistically reduced the expression of MMP13 and NFκB in human OA explants. Overall, sCMC-mediated enhancement of Timp3 efficacy synergistically reduced OA-like traits and demonstrates the potential for OA amelioration.

5,6-Dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) induces apoptosis in breast cancer cells through inhibiting of Mcl-1 expression

The effective treatment of breast cancer remains a profound clinical challenge, especially due to drug resistance and metastasis which unfortunately arise in many patients. The transcription inhibitor 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB), as a selective inhibitor of cyclin-dependent kinase 9, was shown to be effective in inducing apoptosis in various hematopoietic malignancies. However, the anticancer efficacy of DRB against breast cancer is still unclear. Herein, we demonstrated that administration of DRB to the breast cancer cell line led to the inhibition of cellular proliferation and induction of the typical signs of apoptotic cells, including the increases in Annexin V-positive cells, DNA fragmentation, and activation of caspase-7, caspase-9, and poly (ADP ribose) polymerase (PARP). Treatment of DRB resulted in a rapid decline in the myeloid cell leukemia 1 (Mcl-1) protein, whereas levels of other antiapoptotic proteins did not change. Overexpression of Mcl-1 decreased the DRB-induced PARP cleavage, whereas knockdown of Mcl-1 enhanced the effects of DRB on PARP activation, indicating that loss of Mcl-1 accounts for the DRB-mediated apoptosis in MCF-7 cells, but not in T-47D. Furthermore, we found that co-treatment of MCF-7 cells with an inhibitor of AKT (LY294002) or an inhibitor of the proteasome (MG-132) significantly augmented the DRB-induced apoptosis. These data suggested that DRB in combination with LY294002 or MG-132 may have a greater therapeutic potency against breast cancer cells.

Construction of an immune-related gene signature for the prognosis and diagnosis of glioblastoma multiforme

Background

Increasing evidence has suggested that inflammation is related to tumorigenesis and tumor progression. However, the roles of immune-related genes in the occurrence, development, and prognosis of glioblastoma multiforme (GBM) remain to be studied.

Methods

The GBM-related RNA sequencing (RNA-seq), survival, and clinical data were acquired from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), Chinese Glioma Genome Atlas (CGGA), and Gene Expression Omnibus (GEO) databases. Immune-related genes were obtained from the Molecular Signatures Database (MSigDB). Differently expressed immune-related genes (DE-IRGs) between GBM and normal samples were identified. Prognostic genes associated with GBM were selected by Kaplan-Meier survival analysis, Least Absolute Shrinkage and Selection Operator (LASSO)-penalized Cox regression analysis, and multivariate Cox analysis. An immune-related gene signature was developed and validated in TCGA and CGGA databases separately. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to explore biological functions of the signature. The correlation between immune cell infiltration and the signature was analyzed by single-sample gene set enrichment analysis (ssGSEA), and the diagnostic value was investigated. The gene set enrichment analysis (GSEA) was performed to explore the potential function of the signature genes in GBM, and the protein-protein interaction (PPI) network was constructed.

Results

Three DE-IRGs [Pentraxin 3 (PTX3), TNFSF9, and bone morphogenetic protein 2 (BMP2)] were used to construct an immune-related gene signature. Receiver operating characteristic (ROC) curves and Cox analyses confirmed that the 3-gene-based prognostic signature was a good independent prognostic factor for GBM patients. We found that the signature was mainly involved in immune-related biological processes and pathways, and multiple immune cells were disordered between the high- and low-risk groups. GSEA suggested that PTX3 and TNFSF9 were mainly correlated with interleukin (IL)-17 signaling pathway, nuclear factor kappa B (NF-κB) signaling pathway, tumor necrosis factor (TNF) signaling pathway, and Toll-like receptor signaling pathway, and the PPI network indicated that they could interact directly or indirectly with inflammatory pathway proteins. Quantitative real-time PCR (qRT-PCR) indicated that the three genes were significantly different between target tissues.

Conclusion

The signature with three immune-related genes might be an independent prognostic factor for GBM patients and could be associated with the immune cell infiltration of GBM patients.

Novel mitochondria-targeting compounds selectively kill human leukemia cells

Acute myeloid leukemia (AML) is a heterogeneous group of aggressive hematological malignancies commonly associated with treatment resistance, high risk of relapse, and mitochondrial dysregulation. We identified six mitochondria-affecting compounds (PS compounds) that exhibit selective cytotoxicity against AML cells in vitro. Structure-activity relationship studies identified six analogs from two original scaffolds that had over an order of magnitude difference between LD50 in AML and healthy peripheral blood mononuclear cells. Mechanistically, all hit compounds reduced ATP and selectively impaired both basal and ATP-linked oxygen consumption in leukemic cells. Compounds derived from PS127 significantly upregulated production of reactive oxygen species (ROS) in AML cells and triggered ferroptotic, necroptotic, and/or apoptotic cell death in AML cell lines and refractory/relapsed AML primary samples. These compounds exhibited synergy with several anti-leukemia agents in AML, acute lymphoblastic leukemia (ALL), or chronic myelogenous leukemia (CML). Pilot in vivo efficacy studies indicate anti-leukemic efficacy in a MOLM14/GFP/LUC xenograft model, including extended survival in mice injected with leukemic cells pre-treated with PS127B or PS127E and in mice treated with PS127E at a dose of 5 mg/kg. These compounds are promising leads for development of future combinatorial therapeutic approaches for mitochondria-driven hematologic malignancies such as AML, ALL, and CML.

Proteasome activity modulates amyloid toxicity

Alzheimer's disease (AD) is responsible for 60%-80% of identified cases of dementia. While the generation and accumulation of amyloid precursor protein (APP) fragments is accepted as a key step in AD pathogenesis, the precise role of these fragments remains poorly understood. To overcome this deficit, we induced the expression of the soluble C-terminal fragment of APP (C99), the rate-limiting peptide for the generation of amyloid fragments, in yeast that contain thermosensitive mutations in genes encoding proteasome subunits. Our previous work with this system demonstrated that these proteasome-deficient yeast cells, expressing C99 when proteasome activity was blunted, generated amyloid fragments similar to those observed in AD patients. We now report the phenotypic repercussions of inducing C99 expression in proteasome-deficient cells. We show increased levels of protein aggregates, cellular stress and chaperone expression, electron-dense accumulations in the nuclear envelope/ER, abnormal DNA condensation, and an induction of apoptosis. Taken together, these findings suggest that the generation of C99 and its associated fragments in yeast cells with compromised proteasomal activity results in phenotypes that may be relevant to the neuropathological processes observed in AD patients. These data also suggest that this yeast model should be useful for testing therapeutics that target AD-associated amyloid, since it allows for the assessment of the reversal of the perturbed cellular physiology observed when degradation pathways are dysfunctional.

Role of Toll-Like Receptors in Neuroimmune Diseases: Therapeutic Targets and Problems

Toll-like receptors (TLRs) are a class of proteins playing a key role in innate and adaptive immune responses. TLRs are involved in the development and progression of neuroimmune diseases via initiating inflammatory responses. Thus, targeting TLRs signaling pathway may be considered as a potential therapy for neuroimmune diseases. However, the role of TLRs is elusive and complex in neuroimmune diseases. In addition to the inadequate immune response of TLRs inhibitors in the experiments, the recent studies also demonstrated that partial activation of TLRs is conducive to the production of anti-inflammatory factors and nervous system repair. Exploring the mechanism of TLRs in neuroimmune diseases and combining with developing the emerging drug may conquer neuroimmune diseases in the future. Herein, we provide an overview of the role of TLRs in several neuroimmune diseases, including multiple sclerosis, neuromyelitis optica spectrum disorder, Guillain-Barré syndrome and myasthenia gravis. Emerging difficulties and potential solutions in clinical application of TLRs inhibitors will also be discussed.

Isoleucilactucin Ameliorates Coal Fly Ash-Induced Inflammation through the NF-κB and MAPK Pathways in MH-S Cells

We investigated whether isoleucilactucin, an active constituent of Ixeridium dentatum, reduces inflammation caused by coal fly ash (CFA) in alveolar macrophages (MH-S). The anti-inflammatory effects of isoleucilactucin were assessed by measuring the concentration of nitric oxide (NO) and the expression of pro-inflammatory mediators in MH-S cells exposed to CFA-induced inflammation. We found that isoleucilactucin reduced CFA-induced NO generation dose-dependently in MH-S cells. Moreover, isoleucilactucin suppressed CFA-activated proinflammatory mediators, including cyclooxygenase-2 (COX2) and inducible NO synthase (iNOS), and the proinflammatory cytokines such as interleukin-(IL)-1β, IL-6, and tumor necrosis factor (TNF-α). The inhibiting properties of isoleucilactucin on the nuclear translocation of phosphorylated nuclear factor-kappa B (p-NF-κB) were observed. The effects of isoleucilactucin on the NF-κB and mitogen-activated protein kinase (MAPK) pathways were also measured in CFA-stimulated MH-S cells. These results indicate that isoleucilactucin suppressed CFA-stimulated inflammation in MH-S cells by inhibiting the NF-κB and MAPK pathways, which suggest it might exert anti-inflammatory properties in the lung.

The multifaceted NF-kB: are there still prospects of its inhibition for clinical intervention in pediatric central nervous system tumors?

Despite advances in the understanding of the molecular mechanisms underlying the basic biology and pathogenesis of pediatric central nervous system (CNS) malignancies, patients still have an extremely unfavorable prognosis. Over the years, a plethora of natural and synthetic compounds has emerged for the pharmacologic intervention of the NF-kB pathway, one of the most frequently dysregulated signaling cascades in human cancer with key roles in cell growth, survival, and therapy resistance. Here, we provide a review about the state-of-the-art concerning the dysregulation of this hub transcription factor in the most prevalent pediatric CNS tumors: glioma, medulloblastoma, and ependymoma. Moreover, we compile the available literature on the anti-proliferative effects of varied NF-kB inhibitors acting alone or in combination with other therapies in vitro, in vivo, and clinical trials. As the wealth of basic research data continues to accumulate, recognizing NF-kB as a therapeutic target may provide important insights to treat these diseases, hopefully contributing to increase cure rates and lower side effects related to therapy.

Brefeldin A Induces Apoptosis, Inhibits BCR-ABL Activation, and Triggers BCR-ABL Degradation in Chronic Myeloid Leukemia K562 Cells

BACKGROUND

Chronic myeloid leukemia (CML) is a myeloproliferative disease caused by BCR-ABL oncoprotein. Tyrosine kinase inhibitors have been developed to inhibit the activity of BCR-ABL; however, drug resistance and side effect occur in clinic application. Therefore, it is urgent to find novel drugs for CML treatment. Under the guidance of cytotoxic activity, crude extracts of 55 fungal strains from the medicinal mangrove Acanthus ilicifolius were evaluated, and one potent cytotoxic natural compound, brefeldin A (BFA), was discovered from Penicillium sp. (HS-N-29).

OBJECTIVE

This study was aimed to determine the cytotoxic activity of BFA and the effect on the activation and expression of BCR-ABL in K562 cells.

METHOD

We evaluated cytotoxic activity by MTT assay and soft agar clone assay and apoptosis and cell cycle distribution by Muse cell analyzer. The protein level of BCR-ABL and signaling molecules were detected by western blotting, and the mRNA level of BCR-ABL was determined by RT-PCR.

RESULTS

BFA inhibited cell proliferation, induced G2/M cell cycle arrest, and stimulated cell apoptosis in K562 cells. Importantly, for the first time, we revealed that BFA inhibited the activation of BCR-ABL and consequently inhibited the activation of its downstream signaling molecules in K562 cells. Moreover, we found that BFA degraded BCR-ABL without affecting its transcription in K562 cells, and BFA-induced BCR-ABL degradation was related to caspase activation while not to autophagy or ubiquitinated proteasome degradation pathway.

CONCLUSION

Our present results indicate that BFA acts as a dual functional inhibitor and degrader of BCR-ABL, and BFA is a potential compound for chemotherapeutics to overcome CML.

In situ exploring Chidamide, a histone deacetylase inhibitor, induces molecular changes of leukemic T-lymphocyte apoptosis using Raman spectroscopy

Though it has been demonstrated that Chidamide (CS055/HBI-8000), a novel benzamide class of histone deacetylase (HDAC) subtype-selectively inhibitor, reveals better anticancer effect in acute leukemia, but it remains unknown about the precise mechanism of Chidamide-induced acute leukemia cell apoptosis due to the lack of in situ molecular changes information. Based on Raman spectral analysis, we find that the action of Chidamide on Jurkat cell will lead to an addition of an acetyl group to a specific lysine residue at the end of histone amino acid, and greatly enhance the acetylation of histones H1, H2A, H2B, H3, and H4, and then destroy the electrostatic force between the alkaline terminal of the positive charged arginine side chain and the negative charged DNA of phosphate group, finally cause the depolymerization of DNA and histone octamer in chromatin nucleosome depolymerization and the relaxation of chromatin. Accordingly, the accumulation of reactive oxygen species (ROS) and the decreasing of mitochondrial membrane potential (MMP) are observed. For comparison, we also present the corresponding results of suberoylanilide hydroxamic acid (SAHA) and MS-275 inhibitors. The achieved results show that proliferation of Chidamide-treated Jurkat cells is low relative to MS-275 or SAHA, and the action of Chidamide or MS-275 on Jurkat cells lead to obvious increasing in histones H1, H2A, H2B, H3, and H4, whereas the action effect of SAHA is mainly observed in histones H1, H2A, H2B, H3 but weak in histone H4. Moreover, it is found that Chidamide-induced histone H3 acetylation in Jurkat cells is stronger than MS-275 and SAHA. Collectively, by Raman spectral analysis, we achieve the dynamic behavior of biochemical components, molecular conformation and morphological changes of HDAC inhibitors-treated Jurkat cells. Importantly, our research is the first to demonstrate that the action site of HDAC inhibitors on Jurkat cell is located in the DNA minor groove. Most importantly, the application of Raman spectrum in exploring in-situ molecular changes information, histone acetylation modification in epigenetics, drug action sites and cell cycle affected by HDAC inhibitors will supply new idea and reference for the design and modification of HDAC inhibitors.

Chemosensitization by 4-hydroxyphenyl retinamide-induced NF-κB inhibition in acute myeloid leukemia cells

PURPOSE

Inherent and/or acquired multi-drug resistance might be the instigator of treatment failure for acute myeloid leukemia (AML). In the current study, we aimed to explored the chemosensitizing effect of 4-HPR on AML therapy.

METHODS

Luciferase reporter assays were used to test the effect of 4-HPR on transcriptional signaling pathways. The quantitative real-time polymerase chain reaction and immunoblots were used to confirm the role of 4-HPR in NF-κB inhibition, apoptosis, and drug resistance. MTT and flow cytometry assays were applied to test the drug response and chemosensitizing effect of 4-HPR with AML cell lines and primary AML samples.

RESULTS

4-HPR suppressed tumor necrosis factor-α- and daunorubin-induced NF-κB activation in AML cell lines. The expression of anti-apoptotic gene, BCL2, was downregulated, while expressions of pro-apoptotic genes, cIAP, XIAP, and BID, were increased after 4-HPR treatment. Immunoblots showed decreased p65-NF-κB, IκBα, and MDR1, but increased cleaved poly (ADP-ribose) polymerase and BIM. A low concentration of 4-HPR chemosensitized AML cells to daunorubin treatment in vitro.

CONCLUSION

4-HPR-induced NF-κB inhibition was the main driver of the chemosensitizing effect observed in AML cell lines and primary AML samples. These results highlight that 4-HPR might be a promising chemosensitizing agent in AML therapy.

Utilizing Synergistic Potential of Mitochondria-Targeting Drugs for Leukemia Therapy

Acute myeloid leukemia (AML) is an aggressive group of cancers with high mortality rates and significant relapse risks. Current treatments are insufficient, and new therapies are needed. Recent discoveries suggest that AML may be particularly sensitive to chemotherapeutics that target mitochondria. To further investigate this sensitivity, six compounds that target mitochondria [IACS-010759, rotenone, cytarabine, etoposide, ABT-199 (venetoclax), and carbonyl cyanide m-chlorophenylhydrazone] were each paired with six compounds with other activities, including tyrosine kinase inhibitors (midostaurin and dasatinib), glycolytic inhibitors (2-deoxy-D-glucose, 3-bromopyruvate, and lonidamine), and the microtubule destabilizer vinorelbine. The 36 resulting drug combinations were tested for synergistic cytotoxicity against MOLM-13 and OCI-AML2 AML cell lines. Four combinations (IACS-010759 with vinorelbine, rotenone with 2-deoxy-D-glucose, carbonyl cyanide m-chlorophenylhydrazone with dasatinib, and venetoclax with lonidamine) showed synergistic cytotoxicity in both AML cell lines and were selective for tumor cells, as survival of healthy PBMCs was dramatically higher. Among these drug pairs, IACS-010759/vinorelbine decreased ATP level and impaired mitochondrial respiration and coupling efficiency most profoundly. Some of these four treatments were also effective in K-562, KU812 (chronic myelogenous leukemia) and CCRF-CEM, MOLT-4 (acute lymphoblastic leukemia) cells, suggesting that these treatments may have value in treating other forms of leukemia. Finally, two of the four combinations retained high synergy and strong selectivity in primary AML cells from patient samples, supporting the potential of these treatments for patients.

In Vitro Efficacy of Ebselen and BAY 11-7082 Against Naegleria fowleri

Primary amebic meningoencephalitis (PAM) is a fatal infection caused by the free-living ameba Naegleria fowleri, popularly known as the "brain-eating ameba." The drugs of choice in treating PAM are the antifungal amphotericin B and an antileishmanial miltefosine, but these are not FDA-approved for this indication and use of amphotericin B is associated with severe adverse effects. Moreover, very few patients treated with the combination therapy have survived PAM. Therefore, development of efficient drugs is a critical unmet need to avert future deaths of children. Since N. fowleri causes extensive inflammation in the brain it is important to select compounds that can enter brain to kill ameba. In this study, we identified two central nervous system (CNS) active compounds, ebselen and BAY 11-7082 as amebicidal with EC₅₀ of 6.2 and 1.6 μM, respectively. The closely related BAY 11-7085 was also found active against N. fowleri with EC₅₀ similar to BAY 11-7082. We synthesized a soluble ebselen analog, which had amebicidal activity similar to ebselen. Transmission electron microscopy of N. fowleri trophozoites incubated for 48 h with EC₅₀ concentration of ebselen showed alteration in the cytoplasmic membrane, loss of the nuclear membrane, and appearance of electron-dense granules. Incubation of N. fowleri trophozoites with EC₅₀ concentrations of BAY 11-7082 and BAY 11-7085 for 48 h showed the presence of large lipid droplets in the cytoplasm, disruption of cytoplasmic and nuclear membranes and appearance of several vesicles and chromatin residues. Blood-brain barrier permeable amebicidal compounds have potential as new drug leads for Naegleria infection.

Phytochemicals and PI3K Inhibitors in Cancer-An Insight

In today's world of modern medicine and novel therapies, cancer still remains to be one of the prime contributor to the death of people worldwide. The modern therapies improve condition of cancer patients and are effective in early stages of cancer but the advanced metastasized stage of cancer remains untreatable. Also most of the cancer therapies are expensive and are associated with adverse side effects. Thus, considering the current status of cancer treatment there is scope to search for efficient therapies which are cost-effective and are associated with lesser and milder side effects. Phytochemicals have been utilized for many decades to prevent and cure various ailments and current evidences indicate use of phytochemicals as an effective treatment for cancer. Hyperactivation of phosphoinositide 3-kinase (PI3K) signaling cascades is a common phenomenon in most types of cancers. Thus, natural substances targeting PI3K pathway can be of great therapeutic potential in the treatment of cancer patients. This chapter summarizes the updated research on plant-derived substances targeting PI3K pathway and the current status of their preclinical studies and clinical trials.

Alkylating Agent-Induced NRF2 Blocks Endoplasmic Reticulum Stress-Mediated Apoptosis via Control of Glutathione Pools and Protein Thiol Homeostasis

Alkylating agents are a commonly used cytotoxic class of anticancer drugs. Understanding the mechanisms whereby cells respond to these drugs is key to identify means to improve therapy while reducing toxicity. By integrating genome-wide gene expression profiling, protein analysis, and functional cell validation, we herein demonstrated a direct relationship between NRF2 and Endoplasmic Reticulum (ER) stress pathways in response to alkylating agents, which is coordinated by the availability of glutathione (GSH) pools. GSH is essential for both drug detoxification and protein thiol homeostasis within the ER, thus inhibiting ER stress induction and promoting survival, an effect independent of its antioxidant role. NRF2 accumulation induced by alkylating agents resulted in increased GSH synthesis via GCLC/GCLM enzyme, and interfering with this NRF2 response by either NRF2 knockdown or GCLC/GCLM inhibition with buthionine sulfoximine caused accumulation of damaged proteins within the ER, leading to PERK-dependent apoptosis. Conversely, upregulation of NRF2, through KEAP1 depletion or NRF2-myc overexpression, or increasing GSH levels with N-acetylcysteine or glutathione-ethyl-ester, decreased ER stress and abrogated alkylating agents-induced cell death. Based on these results, we identified a subset of lung and head-and-neck carcinomas with mutations in either KEAP1 or NRF2/NFE2L2 genes that correlate with NRF2 target overexpression and poor survival. In KEAP1-mutant cancer cells, NRF2 knockdown and GSH depletion increased cell sensitivity via ER stress induction in a mechanism specific to alkylating drugs. Overall, we show that the NRF2-GSH influence on ER homeostasis implicates defects in NRF2-GSH or ER stress machineries as affecting alkylating therapy toxicity. Mol Cancer Ther; 15(12); 3000-14. ©2016 AACR.

DDA1 promotes stage IIB-IIC colon cancer progression by activating NFκB/CSN2/GSK-3β signaling

Conventional high-recurrence risk factors are not sufficient to predict post-operative risk of tumor recurrence or sensitivity to 5-fluorouracil (5-FU)-based chemotherapy for stage II colon cancer. DDA1, an evolutionarily conserved gene located at 19p13.11, may be involved in the activation of nuclear factor kappaB (NFκB). This study aimed to investigate whether DDA1 contributes to tumorigenesis and progression of stage II colon cancer via activation of the NFκB pathway. We found that positive expression of DDA1 alone or in combination with p65 nuclear translocation correlated with increased risk of tumor recurrence in patients with stage IIB-IIC colon cancer. DDA1 overexpression in colon cancer lines promoted cell proliferation, facilitated cell cycle progression, inhibited 5-FU-induced apoptosis, enhanced invasion, and induced the epithelial-mesenchymal transition. Suppression of DDA1 inhibited tumor progression, and reduced tumor growth in vivo. We also demonstrated that DDA1-mediated tumor progression is associated with the activation of the NFκB/COP9 signalosome 2(CSN2)/glycogen synthase kinase3β (GSK3β) pathway. These results indicate that DDA1 promotes colon cancer progression through activation of NFκB/CSN2/GSK3β signaling. DDA1, together with NFκB activation status, may serve as a sensitive biomarker for tumor recurrence risk and prognosis in patients with stage IIB-IIC colon cancers.

Evaluating ancient Egyptian prescriptions today: Anti-inflammatory activity of Ziziphus spina-christi

BACKGROUND

Ziziphus spina-christi (L.) Desf. (Christ's Thorn Jujube) is a wild tree today found in Jordan, Israel, Egypt, and some parts of Africa, which was already in use as a medicinal plant in Ancient Egypt. In ancient Egyptian prescriptions, it was used in remedies against swellings, pain, and heat, and thus should have anti-inflammatory effects. Nowadays, Z. spina-christi, is used in Egypt (by Bedouins, and Nubians), the Arabian Peninsula, Jordan, Iraq, and Morocco against a wide range of illnesses, most of them associated with inflammation. Pharmacological research undertaken to date suggests that it possesses anti-inflammatory, hypoglycemic, hypotensive and anti-microbial effects. The transcription factor NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) is critical in inflammation, proliferation and involved in various types of cancer. Identification of new anti-inflammatory compounds might be an effective strategy to target inflammatory disorders and cancer. Therefore, extracts from Z. spina-christi are investigated in terms of their anti-inflammatory effects. Our intention is to evaluate the effects of Z. spina-christi described in ancient Egyptian papyri, and to show whether the effects can be proven with modern pharmacological methods. Furthermore, we determine the active ingredients in crude extracts for their inhibitory activity toward NF-κB pathway.

MATERIALS AND METHODS

To determine the active ingredients of Z. spina-christi, we fractionated the extracts for bioassays and identified the active compounds. Epigallocatechin, gallocatechin, spinosin, 6''' feruloylspinosin and 6''' sinapoylspinosin and crude extracts of seed, leaf, root or stem were analyzed for their effect on NF-κB DNA binding by electromobility shift assay (EMSA) and nuclear translocation of NF-κB-p65 by Western blot analysis. The binding mode of the compounds to NF-κB pathway proteins was compared with the known inhibitor, MG-132, by in silico molecular docking calculations. Log10IC50 values of gallocatechin and epigallocatechin as two main compounds of the plant were correlated to the microarray-based mRNA expression of 79 inflammation-related genes in cell lines of the National Cancer Institute (NCI, USA) as determined. The expression of 17 genes significantly correlated to the log10IC50 values for gallocatechin or epigallocatechin.

RESULTS

Nuclear p65 protein level decreased upon treatment with each extract and compound. Root and seed extracts inhibited NF-κB-DNA binding as shown by EMSA. The compounds showed comparable binding energies and similar docking poses as MG-132 on the target proteins.

CONCLUSION

Z. spina-christi might possess anti-inflammatory activity as assumed by ancient Egyptian prescriptions. Five compounds contributed to this bioactivity, i.e. epigallocatechin, gallocatechin, spinosin, 6''' feruloylspinosin and 6''' sinapoylspinosin as shown in vitro and in silico.

In vitro evaluation of antitumoral efficacy of catalase in combination with traditional chemotherapeutic drugs against human lung adenocarcinoma cells

Lung cancer is the most lethal cancer-related disease worldwide. Since survival rates remain poor, there is an urgent need for more effective therapies that could increase the overall survival of lung cancer patients. Lung tumors exhibit increased levels of oxidative markers with altered levels of antioxidant defenses, and previous studies demonstrated that the overexpression of the antioxidant enzyme catalase (CAT) might control tumor proliferation and aggressiveness. Herein, we evaluated the effect of CAT treatment on the sensitivity of A549 human lung adenocarcinoma cells toward various anticancer treatments, aiming to establish the best drug combination for further therapeutic management of this disease. Exponentially growing A549 cells were treated with CAT alone or in combination with chemotherapeutic drugs (cisplatin, 5-fluorouracil, paclitaxel, daunorubicin, and hydroxyurea). CalcuSyn(®) software was used to assess CAT/drug interactions (synergism or antagonism). Growth inhibition, NFκB activation status, and redox parameters were also evaluated in CAT-treated A549 cells. CAT treatment caused a cytostatic effect, decreased NFκB activation, and modulated the redox parameters evaluated. CAT treatment exhibited a synergistic effect among most of the anticancer drugs tested, which is significantly correlated with an increased H2O2 production. Moreover, CAT combination caused an antagonism in paclitaxel anticancer effect. These data suggest that combining CAT (or CAT analogs) with traditional chemotherapeutic drugs, especially cisplatin, is a promising therapeutic strategy for the treatment of lung cancer.

Screening of Pharmacologically Active Small Molecule Compounds Identifies Antifungal Agents Against Candida Biofilms

Candida species have emerged as important and common opportunistic human pathogens, particularly in immunocompromised individuals. The current antifungal therapies either have toxic side effects or are insufficiently effect. The aim of this study is develop new small-molecule antifungal compounds by library screening methods using Candida albicans, and to evaluate their antifungal effects on Candida biofilms and cytotoxic effects on human cells. Wild-type C. albicans strain SC5314 was used in library screening. To identify antifungal compounds, we screened a small-molecule library of 1,280 pharmacologically active compounds (LOPAC(1280TM)) using an antifungal susceptibility test (AST). To investigate the antifungal effects of the hit compounds, ASTs were conducted using Candida strains in various growth modes, including biofilms. We tested the cytotoxicity of the hit compounds using human gingival fibroblast (hGF) cells to evaluate their clinical safety. Only 35 compounds were identified by screening, which inhibited the metabolic activity of C. albicans by >50%. Of these, 26 compounds had fungistatic effects and nine compounds had fungicidal effects on C. albicans. Five compounds, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate, ellipticine and CV-3988, had strong fungicidal effects and could inhibit the metabolic activity of Candida biofilms. However, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate and ellipticine were cytotoxic to hGF cells at low concentrations. CV-3988 showed no cytotoxicity at a fungicidal concentration. Four of the compounds identified, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate and ellipticine, had toxic effects on Candida strains and hGF cells. In contrast, CV-3988 had fungicidal effects on Candida strains, but low cytotoxic effects on hGF cells. Therefore, this screening reveals agent, CV-3988 that was previously unknown to be antifungal agent, which could be a novel therapies for superficial mucosal candidiasis.

Type III TGF-β receptor inhibits cell proliferation and migration in salivary glands adenoid cystic carcinoma by suppressing NF-κB signaling

It is known that the TGF-β superfamily receptors act as master regulators of cancer progression. However, alteration and role of type III TGF-β receptor (TβRIII, or betaglycan) as the most abundant of the TGF-β receptor has not been explored in salivary gland adenoid cystic carcinoma (ACC). Here, we reported that tumor biopsies and matched normal human salivary glands from patients with ACC were examined for the expression of TβRIII. The expression of TβRIII protein is significantly decreased in ACC patients based on immunohistochemistry and western blot analysis. In vitro, a transient overexpression of TβRIII markedly induced apoptosis and cell cycle arrest in the G2/M phase, thereby inhibited cell viability and migration of ACC-M cells. Co-immunoprecipitation revealed that TβRIII, scaffolding protein-arrestin2 (β-arrestin2) and IκBα formed a complex. Transient overexpression of TβRIII decreased p-p65 expression and increased IκBα expression, which was abolished by knockdown of β-arrestin2. The present study defines TβRIII as a biomarker exerting antitumor action on ACC progression.Gene therapy of TβRIII may be a powerful new approach for ACC disease.

Down-regulation of superoxide dismutase 1 by PMA is involved in cell fate determination and mediated via protein kinase D2 in myeloid leukemia cells

Myeloid leukemia cells maintain a high intracellular ROS level and use redox signals for survival. The metabolism of ROS also affects cell fate, including cell death and differentiation. Superoxide dismutases (SODs) are major antioxidant enzymes that have high levels of expression in myeloid leukemia cells. However, the role of SODs in the regulation of myeloid leukemia cells' biological function is still unclear. To investigate the function of SODs in myeloid leukemia cell death and differentiation, we used myeloid leukemia cell lines K562, MEG-01, TF-1, and HEL cells for this study. We found that PMA-induced megakaryocytic differentiation in myeloid leukemia cells is accompanied by cell death and SOD1 down-regulation, while SOD2 expression is not affected. The role of SOD1 is verified when ATN-224, a SOD1 specific inhibitor, inhibits cell proliferation and promotes cell death in myeloid leukemia cells without PMA treatment. Moreover, inhibition or silencing of SODs further increases cell death and decreases polyploidization induced by PMA while they were partially reversed by SOD1 overexpression. Thus, SOD1 expression is required for myeloid leukemia cell fate determination. In addition, the knockdown of PKD2 reduces cell death and promotes polyploidization induced by PMA. PMA/PKD2-mediated necrosis via PARP cleavage involves both SOD1-dependent and -independent pathways. Finally, ATN-224 enhanced the inhibition of cell proliferation by Ara-C. Taken together, the results demonstrate that SOD1 regulates cell death and differentiation in myeloid leukemia cells. ATN-224 may be beneficial for myeloid leukemia therapy.

Heterodimer-specific TLR2 stimulation results in divergent functional outcomes in B-cell precursor acute lymphoblastic leukemia

Reports of spontaneous acute lymphoblastic leukemia (ALL) remissions following severe bacterial infections suggest that bacterial components may trigger elimination of ALL. To date, TLR2, which recognizes a broad range of bacterial pathogens through TLR1 or TLR6 heterodimerization, has not been fully evaluated for direct effects on ALL. Studies investigating TLR2 signaling in other tumor cell types utilizing single ligands have yielded contradictory results, and comparative, heterodimer-specific analyses of TLR2 stimulation are lacking. In this study, we report that two well-characterized heterodimer-specific TLR2 ligands, Pam3 CSK4 (TLR2/1), and Pam2 CSK4 (TLR2/6), induce ALL cell lines and primary ALL samples to upregulate CD40 expression. However, only Pam3 CSK4 triggers Caspase-8-mediated apoptosis and sensitizes cells to vincristine-mediated cytotoxicity. Consistent with this result, stimulation of ALL cells through TLR2/1 or TLR2/6 activates Mal, p38 and the NF-κB and PI3K signaling pathways with divergent kinetics that may underlie their distinct downstream effects. Our results reveal a novel branching in downstream responses to heterodimer-specific TLR2 stimulation in ALL cells and emphasize the need for comparative studies to determine differential biological effects observed in specific tumor cells. Based on our results, TLR2/1 ligand Pam3 CSK4 possesses potential for generating anti-ALL activity through its direct effects on leukemic blasts.

Dieckol, isolated from the edible brown algae Ecklonia cava, induces apoptosis of ovarian cancer cells and inhibits tumor xenograft growth

PURPOSE

Ecklonia cava is an abundant brown alga and has been reported to possess various bioactive compounds having anti-inflammatory effect. However, the anticancer effects of dieckol, a major active compound in E. cava, are poorly understood. In the present study, we investigated the anti-tumor activity of dieckol and its molecular mechanism in ovarian cancer cells and in a xenograft mouse model .

METHODS

MTT assay, PI staining, and PI and Annexin double staining were performed to study cell cytotoxicity, cell cycle distribution, and apoptosis. We also investigated reactive oxygen species (ROS) production and protein expression using flow cytometry and Western blot analysis, respectively. Anti-tumor effects of dieckol were evaluated in SKOV3 tumor xenograft model.

RESULTS

We found that the E. cava extract and its phlorotannins have cytotoxic effects on A2780 and SKOV3 ovarian cancer cells. Dieckol induced the apoptosis of SKOV3 cells and suppressed tumor growth without any significant adverse effect in the SKOV3-bearing mouse model. Dieckol triggered the activation of caspase-8, caspase-9, and caspase-3, and pretreatment with caspase inhibitors neutralized the pro-apoptotic activity of dieckol. Furthermore, treatment with dieckol caused mitochondrial dysfunction and suppressed the levels of anti-apoptotic proteins. We further demonstrated that dieckol induced an increase in intracellular ROS, and the antioxidant N-acetyl-L-cysteine (NAC) significantly reversed the caspase activation, cytochrome c release, Bcl-2 downregulation, and apoptosis that were caused by dieckol. Moreover, dieckol inhibited the activity of AKT and p38, and overexpression of AKT and p38, at least in part, reversed dieckol-induced apoptosis in SKOV3 cells.

CONCLUSION

These data suggest that dieckol suppresses ovarian cancer cell growth by inducing caspase-dependent apoptosis via ROS production and the regulation of AKT and p38 signaling.

Mechanisms of resistance to apoptosis in the human acute promyelocytic leukemia cell line NB4

Current frontline therapies have improved overall survival in acute promyelocytic leukemia (APL) patients to exceptional rates; however, relapse is still a problem among high-risk and old patients. Therefore, the development of better and safer therapies continues to be a goal in the treatment of this disease. In the present work, we examined three different pathways that hinder cell death in the APL cell line NB4, shedding light on the mechanisms that underlie resistance to apoptosis in these cells and that might help provide them with a proliferative advantage. We found that the proteasome inhibitor MG-132 specifically induces in NB4 cells an Nrf2-mediated antioxidant response which counteracts mitochondria-dependent apoptosis induced by the lipophilic cation dequalinium. More importantly, we also demonstrated that high basal autophagy levels and the gain-of-function of mutant p53 are intrinsic mechanisms of resistance to apoptosis in this cell line. According to our results, the pharmacological inhibition of autophagy and p53 mutants are useful tools to explore resistance to apoptosis in APL and other types of cancer and could be the bases of new therapeutic approaches that improve the efficiency and allow dose reduction of the current treatments.

Inducible nitric oxide synthase mediates MG132 lethality in leukemic cells through mitochondrial depolarization

Proteasomes are highly expressed in rapidly growing neoplastic cells and essential for controlling the cell cycle process and mitochondrial homeostasis. Pharmacological inhibition of the proteasome shows a significant anticancer effect on hematopoietic malignancies that is usually associated with the generation of reactive oxygen species. In this study, we comprehensively investigated the role of endogenous oxidants in various cellular events of K562 leukemic cells in response to treatment with MG132, a proteasome inhibitor. MG132 at 1.4 µM potently triggered G2/M arrest, mitochondrial depolarization, and apoptosis. By such treatment, the protein level of inducible nitric oxide synthase (iNOS) was doubled and cellular oxidants, including nitric oxide, superoxide, and their derivatives, were increasingly produced. In MG132-treated cells, the increase in iNOS-derived oxidants was responsible for mitochondrial depolarization and caspase-dependent apoptosis, but was insignificant in G2/M arrest. The amount of iNOS was negatively correlated with that of manganese superoxide dismutase (MnSOD). Whereas iNOS activity was inhibited by aminoguanidine, cellular MnSOD levels as well as mitochondrial membrane potentials were upregulated, and consequentially G2/M arrest and apoptosis were thoroughly reversed. It is suggested that cells rich in functional mitochondria possess improved proteasome activity, which antagonizes the cytotoxic and cytostatic effects of MG132. In contrast to iNOS, endothelial NOS-driven cGMP-dependent signaling promoted mitochondrial function and survival of MG132-stressed cells. In conclusion, the functional interplay of proteasomes and mitochondria is crucial for leukemic cell growth, wherein iNOS plays a key role.

The ubiquitin-proteasome system is required for the early stages of porcine circovirus type 2 replication

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases (PCVAD). It has been shown that the ubiquitin-proteasome system (UPS) is correlated with viral infection, but its role in PCV2 replication remains unknown. In the present study, we explored the interplay between PCV2 replication and the UPS in PK15 cells and found that treatment with a proteasome inhibitor (MG132 and lactacystin) significantly decreased the PCV2 titer at the early infection stage. We further revealed that inhibition of the UPS did not affect virus entry but decreased viral protein expression and RNA transcription potentially in a cell cycle-dependent manner. PCV2 infection has little effect on the chymotrypsin-like activity, and the gene-silencing of ubiquitin reduced the PCV2 titer, which indicates that the effective replication of PCV2 may be related to protein ubiquitination. Taken together, our data suggested that PCV2 replication requires the UPS machinery, which may represent a potential antiviral target against PCV2.

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UPS inhibition reduced PCV2 titer via depression viral translation and transcription.

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Proteasome inhibitors impair cell cycle progression by prolonging G2/M phase.

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siRNA of ubiquitin decreased the PCV2 titer. The effective replication of PCV2 may be related to protein ubiquitination.

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Proteasome inhibition may represent a potential antiviral target against PCV2.

Extract from Acanthopanax senticosus prevents LPS-induced monocytic cell adhesion via suppression of LFA-1 and Mac-1

A crude extract from Acanthopanax senticosus (AS) has drawn increased attention because of its potentially beneficial activities, including anti-fatigue, anti-stress, anti-gastric-ulcer, and immunoenhancing effects. We previously reported that AS crude extract exerts anti-inflammatory activity through blockade of monocytic adhesion to endothelial cells. However, the underlying mechanisms remained unknown, and so this study was designed to investigate the pathways involved. It was confirmed that AS extract inhibited lipopolysaccharide (LPS)-induced adhesion of monocytes to endothelial cells, and we found that whole extract was superior to eleutheroside E, a principal functional component of AS. A series of PCR experiments revealed that AS extract inhibited LPS-induced expression of genes encoding lymphocyte function-associated antigen-1 (LFA-1) and macrophage-1 antigen (Mac-1) in THP-1 cells. Consistently, protein levels and cell surface expression of LFA-1 and Mac-1 were noticeably reduced upon treatment with AS extract. This inhibitory effect was mediated by the suppression of LPS-induced degradation of IκB-α, a known inhibitor of nuclear factor-κB (NF-κB). In conclusion, AS extract exerts anti-inflammatory activity via the suppression of LFA-1 and Mac-1, lending itself as a potential therapeutic galenical for the prevention and treatment of various inflammatory diseases.

(6)-Gingerolinduced myeloid leukemia cell death is initiated by reactive oxygen species and activation of miR-27b expression

The natural polyphenolic alkanone (6)-gingerol (6G) has established anti-inflammatory and antitumoral properties. However, its precise mechanism of action in myeloid leukemia cells is unclear. In this study, we investigated the effects of 6G on myeloid leukemia cells in vitro and in vivo. The results of this study showed that 6G inhibited proliferation of myeloid leukemia cell lines and primary myeloid leukemia cells while sparing the normal peripheral blood mononuclear cells, in a concentration- and time-dependent manner. Mechanistic studies using U937 and K562 cell lines revealed that 6G treatment induced reactive oxygen species (ROS) generation by inhibiting mitochondrial respiratory complex I (MRC I), which in turn increased the expression of the oxidative stress response-associated microRNA miR-27b and DNA damage. Elevated miR-27b expression inhibited PPARγ, with subsequent inhibition of the inflammatory cytokine gene expression associated with the oncogenic NF-κB pathway, whereas the increased DNA damage led to G2/M cell cycle arrest. The 6G induced effects were abolished in the presence of anti-miR-27b or the ROS scavenger N-acetylcysteine. In addition, the results of the in vivo xenograft experiments in mice indicated that 6G treatment inhibited tumor cell proliferation and induced apoptosis, in agreement with the in vitro studies. Our data provide new evidence that 6G-induced myeloid leukemia cell death is initiated by reactive oxygen species and mediated through an increase in miR-27b expression and DNA damage. The dual induction of increased miR-27b expression and DNA damage-associated cell cycle arrest by 6G may have implications for myeloid leukemia treatment.

Sensitization of U937 leukemia cells to doxorubicin by the MG132 proteasome inhibitor induces an increase in apoptosis by suppressing NF-kappa B and mitochondrial membrane potential loss

Background

The resistance of cancerous cells to chemotherapy remains the main limitation for cancer treatment at present. Doxorubicin (DOX) is a potent antitumor drug that activates the ubiquitin-proteasome system, but unfortunately it also activates the Nuclear factor kappa B (NF-кB) pathway leading to the promotion of tumor cell survival. MG132 is a drug that inhibits I kappa B degradation by the proteasome-avoiding activation of NF-кB. In this work, we studied the sensitizing effect of the MG132 proteasome inhibitor on the antitumor activity of DOX.

Methods

U937 human leukemia cells were treated with MG132, DOX, or both drugs. We evaluated proliferation, viability, apoptosis, caspase-3, -8, and −9 activity and cleavage, cytochrome c release, mitochondrial membrane potential, the Bcl-2 and Bcl-XL antiapoptotic proteins, senescence, p65 phosphorylation, and pro- and antiapoptotic genes.

Results

The greatest apoptosis percentage in U937 cells was obtained with a combination of MG132 + DOX. Likewise, employing both drugs, we observed a decrease in tumor cell proliferation and important caspase-3 activation, as well as mitochondrial membrane potential loss. Therefore, MG132 decreases senescence, p65 phosphorylation, and the DOX-induced Bcl-2 antiapoptotic protein. The MG132 + DOX treatment induced upregulation of proapoptotic genes BAX, DIABLO, NOXA, DR4, and FAS. It also induced downregulation of the antiapoptotic genes BCL-XL and SURVIVIN.

Conclusion

MG132 sensitizes U937 leukemia cells to DOX-induced apoptosis, increasing its anti-leukemic effectiveness.

Connecting Small Molecules with Similar Assay Performance Profiles Leads to New Biological Hypotheses

High-throughput screening allows rapid identification of new candidate compounds for biological probe or drug development. Here, we describe a principled method to generate "assay performance profiles" for individual compounds that can serve as a basis for similarity searches and cluster analyses. Our method overcomes three challenges associated with generating robust assay performance profiles: (1) we transform data, allowing us to build profiles from assays having diverse dynamic ranges and variability; (2) we apply appropriate mathematical principles to handle missing data; and (3) we mitigate the fact that loss-of-signal assay measurements may not distinguish between multiple mechanisms that can lead to certain phenotypes (e.g., cell death). Our method connected compounds with similar mechanisms of action, enabling prediction of new targets and mechanisms both for known bioactives and for compounds emerging from new screens. Furthermore, we used Bayesian modeling of promiscuous compounds to distinguish between broadly bioactive and narrowly bioactive compound communities. Several examples illustrate the utility of our method to support mechanism-of-action studies in probe development and target identification projects.

Blocking Plasmodium falciparum development via dual inhibition of hemoglobin degradation and the ubiquitin proteasome system by MG132

Among key potential drug target proteolytic systems in the malaria parasite Plasmodium falciparum are falcipains, a family of hemoglobin-degrading cysteine proteases, and the ubiquitin proteasomal system (UPS), which has fundamental importance in cellular protein turnover. Inhibition of falcipains blocks parasite development, primarily due to inhibition of hemoglobin degradation that serves as a source of amino acids for parasite growth. Falcipains prefer P2 leucine in substrates and peptides, and their peptidyl inhibitors with leucine at the P2 position show potent antimalarial activity. The peptidyl inhibitor MG132 (Z-Leu-Leu-Leu-CHO) is a widely used proteasome inhibitor, which also has P2 leucine, and has also been shown to inhibit parasite development. However, the antimalarial targets of MG132 are unclear. We investigated whether MG132 blocks malaria parasite development by inhibiting hemoglobin degradation and/or by targeting the UPS. P. falciparum was cultured with inhibitors of the UPS (MG132, epoxomicin, and lactacystin) or falcipains (E64), and parasites were assessed for morphologies, extent of hemoglobin degradation, and accumulation of ubiquitinated proteins. MG132, like E64 and unlike epoxomicin or lactacystin, blocked parasite development, with enlargement of the food vacuole and accumulation of undegraded hemoglobin, indicating inhibition of hemoglobin degradation by MG132, most likely due to inhibition of hemoglobin-degrading falcipain cysteine proteases. Parasites cultured with epoxomicin or MG132 accumulated ubiquitinated proteins to a significantly greater extent than untreated or E64-treated parasites, indicating that MG132 inhibits the parasite UPS as well. Consistent with these findings, MG132 inhibited both cysteine protease and UPS activities present in soluble parasite extracts, and it strongly inhibited recombinant falcipains. MG132 was highly selective for inhibition of P. falciparum (IC₅₀ 0.0476 µM) compared to human peripheral blood mononuclear cells (IC₅₀ 10.8 µM). Thus, MG132 inhibits two distinct proteolytic systems in P. falciparum, and it may serve as a lead molecule for development of dual-target inhibitors of malaria parasites.

Thymoquinone-induced reactive oxygen species causes apoptosis of chondrocytes via PI3K/Akt and p38kinase pathway

Thymoquinone (TQ), a bioactive ingredient of the volatile oil of black seed (Nigella sativa), has been shown to possess anti-neoplastic and anti-inflammatory effects on a variety of tumours. However, the precise mechanism of action is not clear in normal cells such as primary chondrocytes. So, we have investigated the effects of TQ on the apoptosis of chondrocytes with a focus on reactive oxygen species (ROS) production. In in vitro experiments, chondrocytes were cultured with increasing concentrations of TQ for 24 h or with 20 µmol/L TQ for the indicated time periods, and various experiments were performed to detect the apoptotic effects caused by TQ. The results showed that TQ significantly increases apoptosis. Apoptosis was dose- and time-dependently expressed, and the generation of ROS also dramatically increased in a dose-dependent manner. Pretreatment of N-acetyl-L-cysteine (NAC), an inhibitor of ROS, inhibited both TQ-induced apoptosis and ROS generation. Also, TQ up-regulated phosphorylation of phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and mitogen-activated protein kinases ([MAPKs] p38kinase, ERK-1/-2, and JNKinase), and these effects were prevented by pretreatment of NAC. However, pretreatment with inhibitors of PI3K/Akt and MAPKs did not inhibit TQ-caused ROS generation. Among the inhibitors of PI3K/Akt, p38kinase, ERK-1/-2, and JNKinase, pretreatment with LY294002 and SB203580 abolished TQ-induced apoptosis, but PD98059 and SP600125 did not have any effect on TQ-caused apoptosis. These findings suggest that TQ-induced ROS generation regulates apoptosis by modulating PI3K/Akt and p38kinase pathways.

The anti-inflammatory compound BAY-11-7082 is a potent inhibitor of protein tyrosine phosphatases

The families of protein tyrosine phosphatases (PTPs) and protein tyrosine kinases (PTKs) function in a coordinated manner to regulate signal transduction events that are critical for cellular homeostasis. Aberrant tyrosine phosphorylation, resulting from disruption of either PTP or PTK function, has been shown to be the cause of major human diseases, including cancer and diabetes. Consequently, the characterization of small-molecule inhibitors of these kinases and phosphatases may not only provide molecular probes with which to define the significance of particular signaling events, but also may have therapeutic implications. BAY-11-7082 is an anti-inflammatory compound that has been reported to inhibit IκB kinase activity. The compound has an α,β-unsaturated electrophilic center, which confers the property of being a Michael acceptor; this suggests that it may react with nucleophilic cysteine-containing proteins, such as PTPs. In this study, we demonstrated that BAY-11-7082 was a potent, irreversible inhibitor of PTPs. Using mass spectrometry, we have shown that BAY-11-7082 inactivated PTPs by forming a covalent adduct with the active-site cysteine. Administration of the compound caused an increase in protein tyrosine phosphorylation in RAW 264 macrophages, similar to the effects of the generic PTP inhibitor sodium orthovanadate. These data illustrate that BAY-11-7082 is an effective pan-PTP inhibitor with cell permeability, revealing its potential as a new probe for chemical biology approaches to the study of PTP function. Furthermore, the data suggest that inhibition of PTP function may contribute to the many biological effects of BAY-11-7082 that have been reported to date.

Caffeic acid phenylethyl ester and MG132, two novel nonconventional chemotherapeutic agents, induce apoptosis of human leukemic cells by disrupting mitochondrial function

The ability to modulate balance between cell survival and death is recognized for its great therapeutic potential. Therefore, research continues to focus on elucidation of cell machinery and signaling pathways that control cell proliferation and apoptosis. Conventional chemotherapeutic agents often have a cytostatic effect over tumor cells. New natural or synthetic chemotherapeutic agents have a wider spectrum of interesting antitumor activities that merit in-depth studies. In the present work, we aimed at characterizing the molecular mechanism leading to induction of cell death upon treatment of the lymphoblastoid cell line PL104 with caffeic acid phenylethyl ester (CAPE), MG132 and two conventional chemotherapeutic agents, doxorubicine (DOX) and vincristine (VCR). Our results showed several apoptotic hallmarks such as phosphatidylserine (PS) exposure on the outer leaflet of the cell membrane, nuclear fragmentation, and increase sub-G1 DNA content after all treatments. In addition, all four drugs downregulated survivin expression. CAPE and both chemotherapeutic agents reduced Bcl-2, while only CAPE and MG132 significantly increased Bax level. CAPE and VCR treatment induced the collapse of mitochondrial membrane potential (∆ψm). All compounds induced cytochrome c release from mitochondrial compartment to cytosol. However, only MG132 caused the translocation of Smac/DIABLO. Except for VCR treatment, all other drugs increased reactive oxygen species (ROS) production level. All treatments induced activation of caspases 3/7, but only CAPE and MG132 led to the activation of caspase 9. In conclusion, our results indicate that CAPE and MG132 treatment of PL104 cells induced apoptosis through the mitochondrial intrinsic pathway, whereas the apoptotic mechanism induced by DOX and VCR may proceed through the extrinsic pathway.

Curcumin-loaded lipid-core nanocapsules as a strategy to improve pharmacological efficacy of curcumin in glioma treatment

In this study, we developed curcumin-loaded lipid-core nanocapsules (C-LNCs) in an attempt to improve the antiglioma activity of this polyphenol. C-LNC showed nanotechnological properties such as nanometric mean size (196 nm), 100% encapsulation efficiency, polydispersity index below 0.1, and negative zeta potential. The in vitro release assays demonstrated a controlled release of curcumin from lipid-core nanocapsules. In C6 and U251MG gliomas, C-LNC promoted a biphasic delivery of curcumin: the first peak occurred early in the treatment (1-3h), whereas the onset of the second phase occurred after 48 h. In C6 cells, the cytotoxicity of C-LNC was comparable to non-encapsulated curcumin only after 96 h, whereas C-LNCs were more cytotoxic than non-encapsulated curcumin after 24h of incubation in U251MG. Induction of G2/M arrest and autophagy were observed in C-LNC as well as in free-curcumin treatments. In rats bearing C6 gliomas, C-LNC (1.5mg/kg/day, i.p.) decreased the tumor size and malignance and prolonged animal survival when compared to same dose of non-encapsulated drug. In addition, serum markers of tissue toxicity and histological parameters were not altered. Considered overall, the data suggest that the nanoencapsulation of curcumin in LNC is an important strategy to improve its pharmacological efficacy in the treatment of gliomas.

Caffeic acid phenethyl ester protects nigral dopaminergic neurons via dual mechanisms involving haem oxygenase-1 and brain-derived neurotrophic factor

BACKGROUND AND PURPOSE

Caffeic acid phenethyl ester (CAPE) is a component of honey bee propolis that can induce expression of haem oxygenase-1 (HO-1). Because HO-1 induction has been suggested to protect dopaminergic neurons in the substantia nigra, we examined the effect of CAPE in experimental models of dopaminergic neurodegeneration.

EXPERIMENTAL APPROACH

Neuroprotective effect of CAPE was investigated in rat organotypic midbrain slice cultures and in vivo, using a mouse model of dopaminergic neurodegeneration induced by intranigral injection of LPS and intrastriatal injection of 6-hydroxydopamine.

KEY RESULTS

CAPE protected dopaminergic neurons in slice cultures from IFN-γ/LPS-induced injury. The effect of CAPE was inhibited by zinc protoporphyrin IX, an HO-1 inhibitor, and by neutralizing antibody against brain-derived neurotrophic factor (BDNF). A p38 MAPK inhibitor SB203580 prevented activation of NF-E2-related factor 2, attenuated increased expression of HO-1 and BDNF, and blocked the neuroprotective actions of CAPE. In the LPS-injected mouse model, daily intraperitoneal administration of CAPE protected dopaminergic neurons, up-regulated HO-1 and BDNF, and reduced the increase of activated microglia/macrophages. Neuroprotective effects of CAPE against LPS-induced injury was prevented by zinc protoporphyrin IX or anti-BDNF antibody. CAPE protected dopaminergic neurons and alleviated methamphetamine-induced rotational behaviour also in 6-hydroxydopamine hemiparkinsonian mice.

CONCLUSION AND IMPLICATIONS

CAPE is a novel type of neuroprotective agent whose actions are mediated by both HO-1 and BDNF. These findings may provide novel clues to develop neuroprotective agents for treatment of neurodegenerative disorders.

Foxo3a targets mitochondria during guanosine 5'-triphosphate guided erythroid differentiation

Evidence is emerging that Foxo family proteins serve as biochemical signal integrators in complex signaling networks mediating and modulating diverse cellular functions. Herein, we report that besides the well-established function of Foxo3a as a transcriptional regulator of multiple target genes in nucleus, a substantial fraction of Foxo3a translocates to mitochondria leading to disruption of mitochondrial membrane potential, release of cytochrome c and caspase activation during erythroid differentiation mediated by guanosine 5'-triphosphate (GTP). In fact, non transcriptional role of Foxo3a in mitochondria was achieved through the protein-protein interaction with pro-apoptotic protein Bax and its translocation to mitochondrial membrane. Furthermore, our results revealed that mitochondrial localization of Foxo3a was modulated by intracellular GTP content which is sensed by PKC signaling element. Collectively, our findings provided insight into a novel Foxo3a mechanism in leukemia cells which led to engagement of cells in the maturation pathway.

Roles of cell signaling pathways in cell-to-cell contact-mediated Epstein-Barr virus transmission

Epstein-Barr virus (EBV), a human gamma herpesvirus, establishes a life-long latent infection in B lymphocytes and epithelial cells following primary infection. Several lines of evidence indicate that the efficiency of EBV infection in epithelial cells is accelerated up to 10(4)-fold by coculturing with EBV-infected Burkitt's lymphoma (BL) cells compared to infection with cell-free virions, indicating that EBV infection into epithelial cells is mainly mediated via cell-to-cell contact. However, the molecular mechanisms involved in this pathway are poorly understood. Here, we establish a novel assay to assess cell-to-cell contact-mediated EBV transmission by coculturing an EBV-infected BL cell line with an EBV-negative epithelial cell line under stimulation for lytic cycle induction. By using this assay, we confirmed that EBV was transmitted from BL cells to epithelial cells via cell-to-cell contact but not via cell-to-cell fusion. The inhibitor treatments of extracellular signal-regulated kinase (ERK) and nuclear factor (NF)-κB pathways blocked EBV transmission in addition to lytic induction. The blockage of the phosphoinositide 3-kinase (PI3K) pathway impaired EBV transmission coupled with the inhibition of lytic induction. Knockdown of the RelA/p65 subunit of NF-κB reduced viral transmission. Moreover, these signaling pathways were activated in cocultured BL cells and in epithelial cells. Finally, we observed that viral replication was induced in cocultured BL cells. Taken together, our data suggest that cell-to-cell contact induces multiple cell signaling pathways in BL cells and epithelial cells, contributing to the induction of the viral lytic cycle in BL cells and the enhancement of viral transmission to epithelial cells.

Protective effects of 7-difluoromethyl-5,4'-dimethoxygenistein against human aorta endothelial injury caused by lysophosphatidyl choline

7-Difluoromethyl-5,4'-dimethoxygenistein (DFMG) is an active new derivative of genistein (GEN). It has shown effective protection in vascular endothelial injury. To further investigate its potential protective effects and its mechanism probably related to atherosclerosis, in present study, human aorta endothelial cells (HAECs) were chosen and treated with various concentrations of lysophosphatidyl choline (LPC) to establish an experimental model. Results showed that 10.0 μmol/l of LPC was optimal for inducing HAEC injury. DFMG pretreatment was able to prevent HAEC injury induced by LPC and restore cell viability in a concentration-dependent manner. The protective efficacy of DFMG (10.0 μmol/l) was significantly greater than that of GEN (10.0 μmol/l) and vitamin E (50.0 μmol/l). The mechanisms underlying the protective effects of DFMG are related to the activation of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase and to the clearance of intracellular reactive oxygen species. DFMG inhibits the apoptosis of HAECs mediated by LPC involving the blockage of the mitochondrial apoptotic pathway.

Synergism between arsenite and proteasome inhibitor MG132 over cell death in myeloid leukaemic cells U937 and the induction of low levels of intracellular superoxide anion

Increased oxygen species production has often been cited as a mechanism determining synergism on cell death and growth inhibition effects of arsenic-combined drugs. However the net effect of drug combination may not be easily anticipated solely from available knowledge of drug-induced death mechanisms. We evaluated the combined effect of sodium arsenite with the proteasome inhibitor MG132, and the anti-leukaemic agent CAPE, on growth-inhibition and cell death effect in acute myeloid leukaemic cells U937 and Burkitt's lymphoma-derived Raji cells, by the Chou-Talalay method. In addition we explored the association of cytotoxic effect of drugs with changes in intracellular superoxide anion (O₂⁻) levels. Our results showed that combined arsenite+MG132 produced low levels of O₂⁻ at 6h and 24h after exposure and were synergic on cell death induction in U937 cells over the whole dose range, although the combination was antagonistic on growth inhibition effect. Exposure to a constant non-cytotoxic dose of 80μM hydrogen peroxide together with arsenite+MG132 changed synergism on cell death to antagonism at all effect levels while increasing O₂⁻ levels. Arsenite+hydrogen peroxide also resulted in antagonism with increased O₂⁻ levels in U937 cells. In Raji cells, arsenite+MG132 also produced low levels of O₂⁻ at 6h and 24h but resulted in antagonism on cell death and growth inhibition. By contrast, the combination arsenite+CAPE showed high levels of O₂⁻ production at 6h and 24 h post exposure but resulted in antagonism over cell death and growth inhibition effects in U937 and Raji cells. We conclude that synergism between arsenite and MG132 in U937 cells is negatively associated to O₂⁻ levels at early time points after exposure.

TNF mediates the sustained activation of Nrf2 in human monocytes

Modulation of monocyte function is a critical factor in the resolution of inflammatory responses. This role is mediated mainly by the production of TNF-α. Investigations of the actions of TNF have mostly focused on acute activation of other cell types such as fibroblasts and endothelial cells. Less is known about the effects of TNF on monocytes themselves, and little is known about the regulation of cell responses to TNF beyond the activation of NF-κB. In this study, we investigated the regulation of NF-E2-related factor 2 (Nrf2) cyctoprotective responses to TNF in human monocytes. We found that in monocytes TNF induces sustained Nrf2 activation and Nrf2 cytoprotective gene induction in a TNFR1-dependent manner. Under TNF activation, monocytes increased their expression of Nrf2-dependent genes, including NAD(P)H:quinone oxidoreductase 1 and glutamyl cysteine ligase modulatory, but not heme oxygenase-1. We also showed that autocrine TNF secretion was responsible for this sustained Nrf2 response and that Nrf2 activation by TNF was mediated by the generation of reactive oxygen species. Moreover, we showed that Nrf2-mediated gene induction can modulate TNF-induced NF-κB activation. These results show for the first time, to our knowledge, that TNF modulates prolonged Nrf2-induced gene expression, which in turn regulates TNF-induced inflammatory responses.

Stabilization of Nrf2 by tBHQ prevents LPS-induced apoptosis in differentiated PC12 cells

The inflammatory reaction plays an important role in the pathogenesis of the neurodegenerative disorders. tert-butylhydroquinone (tBHQ) exhibits a wide range of pharmacological activities including anti-oxidative and anti-inflammatory action. In this study, we tried to elucidate possible effects of tBHQ on lipopolysaccharide (LPS)-induced inflammatory reaction and its underlying mechanism in neuron-like PC12 cells. tBHQ inhibited LPS-induced generation of reactive oxygen species (ROS) and elevation of intracellular calcium level. It also inhibited LPS-induced cyclooxygenase 2 (COX-2), TNF-α, nuclear factor KappaB (NF-kB), and caspase-3 expression in a dose-dependent manner while stabilizing nuclear factor-erythroid 2 p45-related factor 2. Moreover, the phosphorylations of p38, ERK1/2, and JNK were suppressed by tBHQ. These results suggest that the anti-inflammatory properties of tBHQ might result from inhibition of COX-2 and TNF-α expression, inhibition of NF-kB nuclear translocation along with suppression of MAP kinases (p38, ERK1/2, and JNK) phosphorylation in PC12 cells, so may be a useful agent for prevention of inflammatory diseases.