In vitro and in vivo anti-inflammatory activity of Phyllanthus acidus methanolic extract

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus acidus (L.) Skeels (Phyllanthaceae) has traditionally been used to treat gastric trouble, rheumatism, bronchitis, asthma, respiratory disorders, and hepatitis. Despite this widespread use, the pharmacological activities of this plant and their molecular mechanisms are poorly understood. Therefore, we evaluated the immunopharmacological activities of the methanolic extract of the aerial parts of this plant (Pa-ME) and validated its pharmacological targets.

MATERIALS AND METHODS

Lipopolysaccharide (LPS)-treated macrophages, an HCl/EtOH-induced gastritis model, and an acetic acid-injected capillary permeability mouse model were employed to evaluate the anti-inflammatory activity of Pa-ME. Potentially active anti-inflammatory components of this extract were identified by HPLC. The molecular mechanisms of the anti-inflammatory activity were studied by kinase assays, reporter gene assays, immunoprecipitation analysis, and overexpression of target enzymes.

RESULTS

Pa-ME suppressed the production of nitric oxide (NO) and prostaglandin E2 (PGE2) and prevented morphological changes in LPS-treated RAW264.7 cells. Moreover, both HCl/EtOH-induced gastric damage and acetic acid-triggered vascular permeability were restored by orally administered Pa-ME. Furthermore, this extract downregulated the expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 and reduced the nuclear levels of NF-κB. Signalling events upstream of NF-κB translocation, such as phosphorylation of Src and Syk and formation of Src/Syk signalling complexes, were also inhibited by Pa-ME. The enzymatic activities of Src and Syk were also suppressed by Pa-ME. Moreover, Src-induced and Syk-induced luciferase activity and p85/Akt phosphorylation were also inhibited by Pa-ME. Of the identified flavonoids, kaempferol and quercetin were revealed as partially active anti-inflammatory components in Pa-ME.

CONCLUSION

Pa-ME exerts anti-inflammatory activity in vitro and in vivo by suppressing Src, Syk, and their downstream transcription factor, NF-κB.

A Phase I First-in-Human Study of Enoticumab (REGN421), a Fully Human Delta-like Ligand 4 (Dll4) Monoclonal Antibody in Patients with Advanced Solid Tumors

PURPOSE

Enoticumab (REGN421) is a fully human IgG1 monoclonal antibody that binds human Dll4 and disrupts Notch-mediated signaling. The main objectives of this trial were to determine the safety, dose-limiting toxicities (DLT), pharmacokinetics (PK), and recommended phase II dose (RP2D) of enoticumab.

EXPERIMENTAL DESIGN

Enoticumab was administered intravenously, with dose escalations from 0.25 to 4 mg/kg every 3 weeks (Q3W) and 0.75 to 3 mg/kg every 2 weeks (Q2W).

RESULTS

Of 53 enrolled patients, 31 patients were treated Q3W and 22 patients were treated Q2W. Two DLTs occurred: grade 3 nausea (0.5 mg/kg Q3W) and grade 3 abdominal pain (1 mg/kg Q2W). An MTD was not reached on either schedule. The most frequent adverse events (AE) were fatigue, nausea, vomiting, hypertension, headache, and anorexia. Six treatment-related serious AEs were reported in 4 patients: brain natriuretic peptide (BNP) increase (0.25 mg/kg Q3W, Gr1), troponin I increase (4 mg/kg Q3W, Gr3), right ventricular dysfunction and pulmonary hypertension (1.5 mg/kg Q2W, both Gr3), and left ventricular dysfunction and pulmonary hypertension (3 mg/kg Q2W, both Gr3). Enoticumab was characterized by nonlinear, target-mediated PK, and had a terminal half-life of 8 to 9 days. With multiple Q2W or Q3W dosing, accumulation was not observed. Antitumor activity included two partial responses (non-small cell lung cancer bronchoalveolar-type with a β-catenin mutation, and ovarian cancer) and 16 patients with stable disease (3> 6 months).

CONCLUSIONS

Enoticumab was tolerated, with RP2D of 4 mg/kg Q3W and 3 mg/kg Q2W based on PK profile and clinical activity. Responses and SD were noted in ovarian cancer and other solid tumors. Clin Cancer Res; 21(12); 2695-703. ©2015 AACR.

Syk is indispensable for CpG-induced activation and differentiation of human B cells

B cells are efficiently activated by CpG oligodeoxynucleotides (ODNs) to produce pro-inflammatory cytokines and antibody (Ab). Here, we describe a so far unidentified, spleen tyrosine kinase (Syk)-dependent pathway, which is indispensable for CpG-induced human B cell activation. We show that triggering of B cells by CpG results in Syk and src kinase phosphorylation, proliferation, as well as cytokine and Ab production independent of the BCR. Notably, all these functions are abrogated when Syk is inhibited. We demonstrate that CpG-induced Syk activation originates from the cell surface in a TLR9-dependent manner. While inhibition of Syk does not influence the uptake of CpG ODNs, activation of the kinase is a prerequisite for the delivery of CpG into TLR9-containing endolysosomes and for the CpG-induced up-regulation of TLR9 expression. Our results reveal an alternative, Syk-dependent pathway of CpG-induced B cell stimulation, which is initiated at the plasma membrane and seems to be an upstream requirement for endosomal TLR9-driven B cell proliferation and differentiation.

Hepatitis B Virus X Protein Sensitizes TRAIL-Induced Hepatocyte Apoptosis by Inhibiting the E3 Ubiquitin Ligase A20

Hepatitis B virus (HBV) infection causes hepatocyte death and liver damage, which may eventually lead to cirrhosis and liver cancer. Hepatitis B virus X protein (HBx) is a key antigen that is critically involved in HBV-associated liver diseases. However, the molecular basis for its pathogenesis, particularly in liver damage, has not been well defined. Herein, we report that HBx was able to enhance the susceptibility of hepatocytes to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Increased sensitivity to TRAIL was associated with HBx-induced upregulation of miR-125a, which, in turn, suppressed the expression of its putative target gene, A20 E3 ligase. Importantly, we demonstrate that the defective expression of A20 impaired the K63-linked polyubiquitination of caspase-8, which reciprocally enhanced the activation of caspase-8, the recruitment of Fas-associated death domain (FADD), and the formation of death-inducing signaling complex (DISC), thereby promoting HBx-mediated apoptotic signaling. Accordingly, antagonizing miR-125a or ectopically expressing A20 in hepatocytes abolished the pro-apoptotic effect of HBx. Conversely, the overexpression of miR-125a or knockdown of A20 mimicked HBx to enhance TRAIL susceptibility in hepatocytes. Thus, we establish, for the first time, a miR-125a/A20-initiated and caspase-8-targeted mechanism by which HBx modulates apoptotic signaling and increases hepatic susceptibility to the damaging agent, which might provide novel insight into HBV-related liver pathology.

Myristoylated alanine-rich C kinase substrate (MARCKS) regulates the expression of proinflammatory cytokines in macrophages through activation of p38/JNK MAPK and NF-κB

MARCKS, a substrate of protein kinase C, is involved in various processes associated with cytoskeletal movement. Although the expression of MARCKS is highly induced in macrophages, its role in macrophage function has not been studied in detail. Notably, the suppression of MARCKS expression in macrophage cell lines blocked LPS-induced expression of TNF-α at the transcriptional level. Treatment of macrophages with MARCKS N-terminus sequence (MANS) and effector domain (ED) peptides, which mimic functional domains and block the phosphorylation of MARCKS, suppressed the LPS-induced expression of TNF-α through suppression of p38 and JNK MAPKs and NF-κB. Treatment of mice with MANS peptide reduced serum TNF-α and IL-6 levels and resulted in 40% survival of mice after the administration of a lethal dose of LPS. These data demonstrate that MARCKS is involved in the regulation of proinflammatory cytokine expression in macrophages and that MARCKS-derived peptides can be used to suppress inflammatory responses.

Selective Inhibitors of Cyclin G Associated Kinase (GAK) as Anti-Hepatitis C Agents

Cyclin G associated kinase (GAK) emerged as a promising drug target for the treatment of viral infections. However, no potent and selective GAK inhibitors have been reported in the literature to date. This paper describes the discovery of isothiazolo[5,4-b]pyridines as selective GAK inhibitors, with the most potent congeners displaying low nanomolar binding affinity for GAK. Cocrystallization experiments revealed that these compounds behaved as classic type I ATP-competitive kinase inhibitors. In addition, we have demonstrated that these compounds exhibit a potent activity against hepatitis C virus (HCV) by inhibiting two temporally distinct steps in the HCV life cycle (i.e., viral entry and assembly). Hence, these GAK inhibitors represent chemical probes to study GAK function in different disease areas where GAK has been implicated (including viral infection, cancer, and Parkinson's disease).

ERK1/2 pathway is involved in renal gluconeogenesis inhibition under conditions of lowered NADPH oxidase activity

The aim of this study was to elucidate the mechanisms involved in the inhibition of renal gluconeogenesis occurring under conditions of lowered activity of NADPH oxidase (Nox), the enzyme considered to be one of the main sources of reactive oxygen species in kidneys. The in vitro experiments were performed on primary cultures of rat renal proximal tubules, with the use of apocynin, a selective Nox inhibitor, and TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a potent superoxide radical scavenger. In the in vivo experiments, Zucker diabetic fatty (ZDF) rats, a well established model of diabetes type 2, were treated with apocynin solution in drinking water. The main in vitro findings are the following: (1) both apocynin and TEMPOL attenuate the rate of gluconeogenesis, inhibiting the step catalyzed by phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme of the process; (2) in the presence of the above-noted compounds the expression of PEPCK and the phosphorylation of transcription factor CREB and ERK1/2 kinases are lowered; (3) both U0126 (MEK inhibitor) and 3-(2-aminoethyl)-5-((4-ethoxyphenyl)methylene)-2,4-thiazolidinedione (ERK inhibitor) diminish the rate of glucose synthesis via mechanisms similar to those of apocynin and TEMPOL. The observed apocynin in vivo effects include: (1) slight attenuation of hyperglycemia; (2) inhibition of renal gluconeogenesis; (3) a decrease in renal PEPCK activity and content. In view of the results summarized above, it can be concluded that: (1) the lowered activity of the ERK1/2 pathway is of importance for the inhibition of renal gluconeogenesis found under conditions of lowered superoxide radical production by Nox; (2) the mechanism of this phenomenon includes decreased PEPCK expression, resulting from diminished activity of transcription factor CREB; (3) apocynin-evoked inhibition of renal gluconeogenesis contributes to the hypoglycemic action of this compound observed in diabetic animals. Thus, the study has delivered some new insights into the recently discussed issue of the usefulness of Nox inhibition as a potential antidiabetic strategy.

The polarity protein Scribble regulates myelination and remyelination in the central nervous system

The development and regeneration of myelin by oligodendrocytes, the myelin-forming cells of the central nervous system (CNS), requires profound changes in cell shape that lead to myelin sheath initiation and formation. Here, we demonstrate a requirement for the basal polarity complex protein Scribble in CNS myelination and remyelination. Scribble is expressed throughout oligodendroglial development and is up-regulated in mature oligodendrocytes where it is localised to both developing and mature CNS myelin sheaths. Knockdown of Scribble expression in cultured oligodendroglia results in disrupted morphology and myelination initiation. When Scribble expression is conditionally eliminated in the myelinating glia of transgenic mice, myelin initiation in CNS is disrupted, both during development and following focal demyelination, and longitudinal extension of the myelin sheath is disrupted. At later stages of myelination, Scribble acts to negatively regulate myelin thickness whilst suppressing the extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAP) kinase pathway, and localises to non-compact myelin flanking the node of Ranvier where it is required for paranodal axo-glial adhesion. These findings demonstrate an essential role for the evolutionarily-conserved regulators of intracellular polarity in myelination and remyelination.

The polarity protein Scribble regulates the formation and properties of myelin sheaths in the central nervous system during development and after demyelinating injury.

The formation of myelin, a fatty, multilayered structure that surrounds certain neuronal axons in the nervous system, is essential for the proper communication of electrical signals by neurons, acting both as an insulator and to promote metabolic support to the axon. Loss of myelin can have severe functional consequences and trigger serious diseases, such as multiple sclerosis. Bidirectional communication between the oligodendrocytes, the myelinating cells of the central nervous system, and the axon is essential for the proper formation and function of myelin membranes; however, the signals that control myelination by oligodendrocytes in the central nervous system are poorly understood. In this paper, we use a combination of cell culture and animal studies to demonstrate that the protein Scribble, which is known to be a highly evolutionarily conserved regulator of cell polarity, plays a role in controlling whether oligodendrocytes myelinate axons. We show that Scribble regulates the length and thickness of myelin sheaths formed, as well as the tight adhesion of oligodendroglial membranes to the axonal surface, which is required for the organization of the axon into specialized domains at the nodes of Ranvier (gaps formed between the myelin sheaths generated by different cells). In addition, we show that Scribble plays a key role in the repair of myelin sheaths in a mouse model of demyelinating disease. The discovery of novel regulators of myelination in the central nervous system may allow for the identification of novel therapeutic targets for the promotion of myelin repair in patients suffering from demyelinating diseases.

Targeting protein-protein interactions with trimeric ligands: high affinity inhibitors of the MAGUK protein family

PDZ domains in general, and those of PSD-95 in particular, are emerging as promising drug targets for diseases such as ischemic stroke. We have previously shown that dimeric ligands that simultaneously target PDZ1 and PDZ2 of PSD-95 are highly potent inhibitors of PSD-95. However, PSD-95 and the related MAGUK proteins contain three consecutive PDZ domains, hence we envisioned that targeting all three PDZ domains simultaneously would lead to more potent and potentially more specific interactions with the MAGUK proteins. Here we describe the design, synthesis and characterization of a series of trimeric ligands targeting all three PDZ domains of PSD-95 and the related MAGUK proteins, PSD-93, SAP-97 and SAP-102. Using our dimeric ligands targeting the PDZ1-2 tandem as starting point, we designed novel trimeric ligands by introducing a PDZ3-binding peptide moiety via a cysteine-derivatized NPEG linker. The trimeric ligands generally displayed increased affinities compared to the dimeric ligands in fluorescence polarization binding experiments and optimized trimeric ligands showed low nanomolar inhibition towards the four MAGUK proteins, thus being the most potent inhibitors described. Kinetic experiments using stopped-flow spectrometry showed that the increase in affinity is caused by a decrease in the dissociation rate of the trimeric ligand as compared to the dimeric ligands, likely reflecting the lower probability of simultaneous dissociation of all three PDZ ligands. Thus, we have provided novel inhibitors of the MAGUK proteins with exceptionally high affinity, which can be used to further elucidate the therapeutic potential of these proteins.

The autophagy pathway maintained signaling crosstalk with the Keap1-Nrf2 system through p62 in auditory cells under oxidative stress

The main purposes of our study were to consider the effect of autophagy on auditory cells under oxidative stress, and the function of possible crosstalk among p62, Keap1 and Nrf2 in autophagy-deficient auditory cells. First, we described how cell death was induced in auditory cell line (HEI-OC1) exposed to H2O2. We found that the decision for the cell death of auditory cells under oxidative stress depends on the balance between autophagy and necrosis due to ATP depletion, and autophagy plays a cytoprotective function in oxidative stress-induced necrosis. Our data clearly suggested that autophagy was a cell survival mechanism in H2O2-induced cell death, based on the observation that suppression of autophagy by knockdown of Atg7 sensitized, whereas activation of autophagy by rapamycin protected against H2O2-induced cell death. Next, our results regarding the relationship among p62, Nrf2 and Keap1 by siRNA paradoxically showed that p62 creates a positive feedback loop in the Keap1/Nrf2 pathway. Autophagy impaired by Atg7 knockdown degrades Keap1 in a p62-dependent manner, whereas Nrf2 is activated. As a result, the cell death induced by H2O2 was promoted in auditory cells. Taken together, these results suggested that the autophagy pathway maintained signaling crosstalk with the Keap1-Nrf2 system through p62 in auditory cells under oxidative stress.

In vivo and in vitro anti-inflammatory activities of Persicaria chinensis methanolic extract targeting Src/Syk/NF-κB

ETHNOPHARMACOLOGIC RELEVANCE

Persicaria chinensis L. (Polygonaceae) [also synonym as Polygonum chimnense L.] has been used as Chinese traditional medicine to treat ulcer, eczema, stomach ache, and various inflammatory skin diseases. Due to no molecular pharmacological evidence of this anti-inflammatory herbal plant, we investigated the inhibitory mechanisms and target proteins contributing to the anti-inflammatory responses of the plant by using its methanolic extract (Pc-ME).

MATERIALS AND METHODS

We used lipopolysaccharide (LPS)-treated macrophages and a murine HCl/EtOH-induced gastritis model to evaluate the anti-inflammatory activity of Pc-ME. HPLC analysis was employed to identify potential active components of this extract. Molecular approaches including kinase assays, reporter gene assays, immunoprecipitation analysis, and overexpression of target enzymes were used to confirm target enzymes.

RESULTS

Pc-ME inhibited LPS-induced nitric oxide and prostaglandin E2 release by RAW264.7 macrophages and ameliorated HCl/EtOH-induced gastric ulcers in mice. The nuclear translocation of NF-κB (p65 and p50) was suppressed by Pc-ME. Phosphorylation of Src and Syk, their kinase activities, and formation of the signaling complex of these proteins were repressed by Pc-ME. Phosphorylation of p85 and Akt induced by Src or Syk overexpression was blocked by Pc-ME. In the mouse gastritis model, orally administered Pc-ME suppressed the increased phosphorylation of IκBα, Αkt, Src, and Syk. Caffeic acid, kaempferol, and quercetin, identified as major anti-inflammatory components of Pc-ME by HPLC, displayed strong nitric oxide inhibitory activity in LPS-treated macrophages.

CONCLUSION

Pc-ME might play a pivotal ethnopharmacologic role as an anti-inflammatory herbal medicine by targeting Syk and Src kinases and their downstream transcription factor NF-κB.

The WNT inhibitor APCDD1 sustains the expression of β-catenin during the osteogenic differentiation of human dental follicle cells

In hair follicle cells APCDD1 inhibits the canonical WNT/β-Catenin pathway and its inactivation is associated with an autosomal dominant form of hair loss. We analyzed the role of APCDD1 for the osteogenic differentiation in dental follicle cells (DFCs) and identified a new and surprising function. Contrarily to hair follicle cells APCDD1 was crucial for the expression of β-Catenin and for the activity of the TCF/LEF reporter assay in DFCs. In addition, a depletion of APCDD1 inhibits the expression of osteogenic markers such as RUNX2 and decreased the matrix mineralization. However, similar to hair follicle cells in previous studies a control cell culture with oral squamous carcinoma cells showed that APCDD1 inhibits the expression of β-Catenin and of typical target genes of the canonical WNT/β-Catenin pathway. In conclusion, our data disclosed an unusual role of APCDD1 in DFCs during the osteogenic differentiation. APCDD1 sustains the expression and activation of β-Catenin.

Polo-like kinase 1 inhibits DNA damage response during mitosis

In response to genotoxic stress, cells protect their genome integrity by activation of a conserved DNA damage response (DDR) pathway that coordinates DNA repair and progression through the cell cycle. Extensive modification of the chromatin flanking the DNA lesion by ATM kinase and RNF8/RNF168 ubiquitin ligases enables recruitment of various repair factors. Among them BRCA1 and 53BP1 are required for homologous recombination and non-homologous end joining, respectively. Whereas mechanisms of DDR are relatively well understood in interphase cells, comparatively less is known about organization of DDR during mitosis. Although ATM can be activated in mitotic cells, 53BP1 is not recruited to the chromatin until cells exit mitosis. Here we report mitotic phosphorylation of 53BP1 by Plk1 and Cdk1 that impairs the ability of 53BP1 to bind the ubiquitinated H2A and to properly localize to the sites of DNA damage. Phosphorylation of 53BP1 at S1618 occurs at kinetochores and in cytosol and is restricted to mitotic cells. Interaction between 53BP1 and Plk1 depends on the activity of Cdk1. We propose that activity of Cdk1 and Plk1 allows spatiotemporally controlled suppression of 53BP1 function during mitosis.

A novel model of IgE-mediated passive pulmonary anaphylaxis in rats

Mast cells are central effector cells in allergic asthma and are augmented in the airways of asthma patients. Attenuating mast cell degranulation and with it the early asthmatic response is an important intervention point to inhibit bronchoconstriction, plasma exudation and tissue oedema formation. To validate the efficacy of novel pharmacological interventions, appropriate and practicable in vivo models reflecting mast cell-dependent mechanisms in the lung, are missing. Thus, we developed a novel model of passive pulmonary anaphylaxis in rats. Rats were passively sensitized by concurrent intratracheal and intradermal (ear) application of an anti-DNP IgE antibody. Intravenous application of the antigen, DNP-BSA in combination with Evans blue dye, led to mast cell degranulation in both tissues. Quantification of mast cell degranulation in the lung was determined by (1) mediator release into bronchoalveolar lavage, (2) extravasation of Evans blue dye into tracheal and bronchial lung tissue and (3) invasive measurement of antigen-induced bronchoconstriction. Quantification of mast cell degranulation in the ear was determined by extravasation of Evans blue dye into ear tissue. We pharmacologically validated our model using the SYK inhibitor Fostamatinib, the H₁-receptor antagonist Desloratadine, the mast cell stabilizer disodium cromoglycate (DSCG) and the β₂-adrenergic receptor agonist Formoterol. Fostamatinib was equally efficacious in lung and ear. Desloratadine effectively inhibited bronchoconstriction and ear vascular leakage, but was less effective against pulmonary vascular leakage, perhaps reflecting the differing roles for histamine receptor sub-types. DSCG attenuated both vascular leakage in the lung and bronchoconstriction, but with a very short duration of action. As an inhaled approach, Formoterol was more effective in the lung than in the ear. This model of passive pulmonary anaphylaxis provides a tissue relevant readout of early mast cell activity and pharmacological benchmarking broadly reflects responses observed in patients with asthma.

Dll4 blockade potentiates the anti-tumor effects of VEGF inhibition in renal cell carcinoma patient-derived xenografts

Background

The Notch ligand Delta-like 4 (Dll4) is highly expressed in vascular endothelium and has been shown to play a pivotal role in regulating tumor angiogenesis. Blockade of the Dll4-Notch pathway in preclinical cancer models has been associated with non-productive angiogenesis and reduced tumor growth. Given the cross-talk between the vascular endothelial growth factor (VEGF) and Delta-Notch pathways in tumor angiogenesis, we examined the activity of a function-blocking Dll4 antibody, REGN1035, alone and in combination with anti-VEGF therapy in renal cell carcinoma (RCC).

Methods and Results

Severe combined immunodeficiency (SCID) mice bearing patient-derived clear cell RCC xenografts were treated with REGN1035 and in combination with the multi-targeted tyrosine kinase inhibitor sunitinib or the VEGF blocker ziv-aflibercept. Immunohistochemical and immunofluorescent analyses were carried out, as well as magnetic resonance imaging (MRI) examinations pre and 24 hours and 2 weeks post treatment. Single agent treatment with REGN1035 resulted in significant tumor growth inhibition (36–62%) that was equivalent to or exceeded the single agent anti-tumor activity of the VEGF pathway inhibitors sunitinib (38–54%) and ziv-aflibercept (46%). Importantly, combination treatments with REGN1035 plus VEGF inhibitors resulted in enhanced anti-tumor effects (72–80% growth inhibition), including some tumor regression. Magnetic resonance imaging showed a marked decrease in tumor perfusion in all treatment groups. Interestingly, anti-tumor efficacy of the combination of REGN1035 and ziv-aflibercept was also observed in a sunitinib resistant ccRCC model.

Conclusions

Overall, these findings demonstrate the potent anti-tumor activity of Dll4 blockade in RCC patient-derived tumors and a combination benefit for the simultaneous targeting of the Dll4 and VEGF signaling pathways, highlighting the therapeutic potential of this treatment modality in RCC.

Small-molecule inhibitors at the PSD-95/nNOS interface attenuate MPP+-induced neuronal injury through Sirt3 mediated inhibition of mitochondrial dysfunction

Post-synaptic density protein 95 (PSD-95) links neuronal nitric oxide synthase (nNOS) with the N-methyl-D-aspartic acid (NMDA) receptor in the central nervous system, and this molecular complex has been implicated in regulating neuronal excitability in several neurological disorders. Here, small-molecule inhibitors of the PSD-95/nNOS interaction, IC87201 and ZL006 were tested for neuroprotective effects in an in vitro Parkinson's disease (PD) model. We now report that IC87201 and ZL006 reduced MPP(+)-induced neuronal injury and apoptotic cell death in a dose-dependent manner in cultured cortical neurons. These protective effects were associated with suppressed mitochondrial dysfunction, as evidenced by decreased reactive oxygen species (ROS) generation, cytochrome c release, mitochondrial membrane potential (MMP) collapse, and the preserved mitochondrial complex I activity and ATP synthesis. IC87201 and ZL006 also preserved intracellular homeostasis through mitigating mitochondrial Ca(2+) uptake and promoting mitochondrial Ca(2+) buffering capacity. Moreover, treatment with IC87201 and ZL006 significantly increased the expression of Sirt3 after MPP(+) exposure, and knockdown of Sirt3 using specific targeted small interfere RNA (siRNA) partially nullified the protective effects induced by these two inhibitors. These data strongly support the hypothesis that targeting the PSD-95/nNOS interaction produces neuroprotective effects and may represent a novel class of therapeutics for PD as well as other neurological diseases where detrimental NMDA receptor signaling plays a major role.

Signal therapy of NF1-deficient tumor xenograft in mice by the anti-PAK1 drug FK228

PAK1, a Rac/CDC42-dependent Ser/Thr kinase, is required for the malignant growth of RAS transformants as well as both NF1-deficient and NF2-deficient cancer cells. FK228, a histone deacetylase (HDAC) inhibitor, suppresses the growth of more than 70% of human cancers in vivo including RAS transformants, breast cancers and prostate cancers by activating a set of genes including the tumor suppressors gelsolin and p21(WAF1), that block upstream and downstream of PAK1, respectively. Here we demonstrate that (1) the anti-PAK1 drug FK228 (0.1 nM) completely blocks the growth of both NF1-deficient and NF2-deficient cancer cells in vitro, and that (2) FK228 (2.5 mg/kg, i.p., twice a week) causes the complete regression of an NF1-deficient human malignant peripheral nerve sheath tumor (MPNST) xenograft in nude mice. This is the very first case where a chemical drug in clinical trials for cancers has ever worked so effectively on neurofibromatosis (experimental neurofibromas) in vivo.

BRAF inhibitor-associated ERK activation drives development of chronic lymphocytic leukemia

Patients with BRAFV600E/K-driven melanoma respond to the BRAF inhibitor vemurafenib due to subsequent deactivation of the proliferative RAS/RAF/MEK/ERK pathway. In BRAF WT cells and those with mutations that activate or result in high levels of the BRAF activator RAS, BRAF inhibition can lead to ERK activation, resulting in tumorigenic transformation. We describe a patient with malignant melanoma who developed chronic lymphocytic leukemia (CLL) in the absence of RAS mutations during vemurafenib treatment. BRAF inhibition promoted patient CLL proliferation in culture and in murine xenografts and activated MEK/ERK in primary CLL cells from additional patients. BRAF inhibitor-driven ERK activity and CLL proliferation required B cell antigen receptor (BCR) activation, as inhibition of the BCR-proximal spleen tyrosine kinase (SYK) reversed ERK hyperactivation and proliferation of CLL cells from multiple patients, while inhibition of the BCR-distal Bruton tyrosine kinase had no effect. Additionally, the RAS-GTP/RAS ratio in primary CLL cells exposed to vemurafenib was reduced upon SYK inhibition. BRAF inhibition increased mortality and CLL expansion in mice harboring CLL xenografts; however, SYK or MEK inhibition prevented CLL proliferation and increased animal survival. Together, these results suggest that BRAF inhibitors promote B cell malignancies in the absence of obvious mutations in RAS or other receptor tyrosine kinases and provide a rationale for combined BRAF/MEK or BRAF/SYK inhibition.

Luteolin suppresses cancer cell proliferation by targeting vaccinia-related kinase 1

Uncontrolled proliferation, a major feature of cancer cells, is often triggered by the malfunction of cell cycle regulators such as protein kinases. Recently, cell cycle-related protein kinases have become attractive targets for anti-cancer therapy, because they play fundamental roles in cellular proliferation. However, the protein kinase-targeted drugs that have been developed so far do not show impressive clinical results and also display severe side effects; therefore, there is undoubtedly a need to investigate new drugs targeting other protein kinases that are critical in cell cycle progression. Vaccinia-related kinase 1 (VRK1) is a mitotic kinase that functions in cell cycle regulation by phosphorylating cell cycle-related substrates such as barrier-to-autointegration factor (BAF), histone H3, and the cAMP response element (CRE)-binding protein (CREB). In our study, we identified luteolin as the inhibitor of VRK1 by screening a small-molecule natural compound library. Here, we evaluated the efficacy of luteolin as a VRK1-targeted inhibitor for developing an effective anti-cancer strategy. We confirmed that luteolin significantly reduces VRK1-mediated phosphorylation of the cell cycle-related substrates BAF and histone H3, and directly interacts with the catalytic domain of VRK1. In addition, luteolin regulates cell cycle progression by modulating VRK1 activity, leading to the suppression of cancer cell proliferation and the induction of apoptosis. Therefore, our study suggests that luteolin-induced VRK1 inhibition may contribute to establish a novel cell cycle-targeted strategy for anti-cancer therapy.

Involvement of YAP, TAZ and HSP90 in contact guidance and intercellular junction formation in corneal epithelial cells

The extracellular environment possesses a rich milieu of biophysical and biochemical signaling cues that are simultaneously integrated by cells and influence cellular phenotype. Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (WWTR1; TAZ), two important signaling molecules of the Hippo pathway, have been recently implicated as nuclear relays of cytoskeletal changes mediated by substratum rigidity and topography. These proteins intersect with other important intracellular signaling pathways (e.g. Wnt and TGFβ). In the cornea, epithelial cells adhere to the stroma through a 3-dimensional topography-rich basement membrane, with features in the nano-submicron size-scale that are capable of profoundly modulating a wide range of fundamental cell behaviors. The influences of substratum-topography, YAP/TAZ knockdown, and HSP90 inhibition on cell morphology, YAP/TAZ localization, and the expression of TGFβ2 and CTGF, were investigated. The results demonstrate (a) that knockdown of TAZ enhances contact guidance in a YAP dependent manner, (b) that CTGF is predominantly regulated by YAP and not TAZ, and (c) that TGFβ2 is regulated by both YAP and TAZ in these cells. Additionally, inhibition of HSP90 resulted in nuclear localization and subsequent transcriptional-activation of YAP, formation of cell-cell junctions and co-localization of E-cadherin and β-catenin at adherens junctions. Results presented in this study reflect the complexities underlying the molecular relationships between the cytoskeleton, growth factors, heat shock proteins, and co-activators of transcription that impact mechanotransduction. The data reveal the importance of YAP/TAZ on the cell behaviors, and gene and protein expression.

Infection risk in patients with rheumatoid arthritis treated with etanercept or adalimumab

OBJECTIVES

To compare the risk of infection for rheumatoid arthritis (RA) patients who took etanercept or adalimumab medication in a nationwide population.

METHODS

RA patients who took etanercept or adalimumab were identified in the Taiwan's National Health Insurance Research Database. The composite outcome of serious infections, including hospitalization for infection, reception of an antimicrobial injection, and tuberculosis were followed for 365 days. A Kaplan-Meier survival curve with a log-rank test and Cox proportional hazards regression were used to compare risks of infection between the two cohorts of tumor necrosis factor (TNF)-α antagonists users. Hazard ratios (HRs) were obtained and adjusted with propensity scores and clinical factors. Sensitivity analyses and subgroup analyses were also performed.

RESULTS

In total, 1660 incident etanercept users and 484 incident adalimumab users were eligible for the analysis. The unadjusted HR for infection of the etanercept users was significantly higher than that of the adalimumab users (HR: 1.93; 95% confidence interval (CI): 1.09-3.42; p=0.024). The HRs were 2.04 (95% CI: 1.14-3.65; p=0.016) and 2.02 (95% CI: 1.13-3.61; p=0.018) after adjusting for propensity scores and for propensity scores in addition to clinical factors, respectively. The subgroup analyses revealed that HRs for composite infection was significantly higher in patient subgroups of older age, female, as well as patients who did not have DM, COPD, and hospitalization history at the baseline.

CONCLUSION

In this head-to-head cohort study involving a nationwide population of patients with RA, etanercept users demonstrated a higher risk of infection than adalimumab users. Results of this study suggest the possible existence of an intra-class difference in infection risk among TNF-α antagonists.

GADD45γ induces G2/M arrest in human pharynx and nasopharyngeal carcinoma cells by cucurbitacin E

Nasopharyngeal carcinoma (NPC) is a common form of malignant cancer, for which radiotherapy or chemotherapy are the main treatment methods. Cucurbitacin E (CuE) is a natural compound-based drug which from the climbing stem of Cucumic melo L (Guadi). Previously shown to be an antifeedant as well as a potent chemopreventive agent against several types of cancer. The present study, investigated anti-proliferation and cell cycle G2/M arrest induced by CuE in Detroit 562 cells (pharynx carcinoma) and HONE-1 (nasopharyngeal carcinoma) cells. Results indicate that the cytotoxicity is associated with accumulation in G2/M cell-cycle phases. CuE produced cell cycle arrest as well as the downregulation of cyclin B1 and CDC2 expression. In addition, treated cells with CuE and GADD45γ SiRNA that also coincided with GADD45γ gene activation in cell cycle arrest. Both effects increased proportionally with the dose of CuE; however, proliferation inhibition and mitosis delay was dependant on the amount of CuE treatment in the cancer cells.

Fragment-based identification and optimization of a class of potent pyrrolo[2,1-f][1,2,4]triazine MAP4K4 inhibitors

MAP4K4 has been shown to regulate key cellular processes that are tied to disease pathogenesis. In an effort to generate small molecule MAP4K4 inhibitors, a fragment-based screen was carried out and a pyrrolotriazine fragment with excellent ligand efficiency was identified. Further modification of this fragment guided by X-ray crystal structures and molecular modeling led to the discovery of a series of promising compounds with good structural diversity and physicochemical properties. These compounds exhibited single digit nanomolar potency and compounds 35 and 44 achieved good in vivo exposure.

Global phosphoproteomics of activated B cells using complementary metal ion functionalized soluble nanopolymers

Engagement of the B cell receptor for antigen (BCR) leads to immune responses through a cascade of intracellular signaling events. Most studies to date have focused on the BCR and protein tyrosine phosphorylation. Because spleen tyrosine kinase, Syk, is an upstream kinase in multiple BCR-regulated signaling pathways, it also affects many downstream events that are modulated through the phosphorylation of proteins on serine and threonine residues. Here, we report a novel phosphopeptide enrichment strategy and its application to a comprehensive quantitative phosphoproteomics analysis of Syk-dependent downstream signaling events in B cells, focusing on serine and threonine phosphorylation. Using a combination of the Syk inhibitor piceatannol, SILAC quantification, peptide fractionation, and complementary PolyMAC-Ti and PolyMAC-Zr enrichment techniques, we analyzed changes in BCR-stimulated protein phosphorylation that were dependent on the activity of Syk. We identified and quantified over 13,000 unique phosphopeptides, with a large percentage dependent on Syk activity in BCR-stimulated B cells. Our results not only confirmed many known functions of Syk, but more importantly, suggested many novel roles, including in the ubiquitin proteasome pathway, that warrant further exploration.

COX-2 inhibitors arrest prostate cancer cell cycle progression by down-regulation of kinetochore/centromere proteins

BACKGROUND

Previous studies have shown that COX-2 inhibitors inhibit cancer cell proliferation. However, the molecular mechanism remains elusive.

METHODS

Prostate cancer LNCaP, 22Rv1, and PC3 cells were cultured and treated with the COX-2 inhibitors celecoxib and CAY10404. Knockdown of COX-2 in LNCaP cells was carried out using lentiviral vector-loaded COX-2 shRNA. Cell cycle progression and cell proliferation were analyzed by flow cytometry, microscopy, cell counting, and the MTT assay. The antagonists of EP1, EP2, EP3, and EP4 were used to examine the effects of the PGE2 signaling. The effect of COX-2 inhibitors and COX-2 knockdown on expression of the kinetochore/centromere genes and proteins was determined by RT-PCR and immunoblotting.

RESULTS

Treatment with the COX-2 inhibitors celecoxib and CAY10404 or knockdown of COX-2 significantly inhibited prostate cancer cell proliferation. Flow-cytometric analysis and immunofluorescent staining confirmed the cell cycle arrested at the G2/M phase. Biochemical analysis showed that inhibition of COX-2 or suppression of COX-2 expression induced a dramatic down-regulation of key proteins in the kinetochore/centromere assembly, such as ZWINT, Cdc20, Ndc80, CENP-A, Bub1, and Plk1. Furthermore, the EP1 receptor antagonist SC51322, but not the EP2, EP3, and EP4 receptor antagonists, produced similar effects to the COX-2 inhibitors on cell proliferation and down-regulation of kinetochore/centromere proteins, suggesting that the effect of the COX-2 inhibition is through inactivation of the EP1 receptor signaling.

CONCLUSIONS

Our studies indicate that inhibition of COX-2 can arrest prostate cancer cell cycle progression through inactivation of the EP1 receptor signaling and down-regulation of kinetochore/centromere proteins.