Celecoxib inhibits interleukin-12 alphabeta and beta2 folding and secretion by a novel COX2-independent mechanism involving chaperones of the endoplasmic reticulum

Biogenesis and engineering of interleukin 12 family cytokines

Interleukin 12 (IL-12) family cytokines are secreted proteins that regulate immune responses. Each family member is a heterodimer and nature uses shared building blocks to assemble the functionally distinct IL-12 cytokines. In recent years we have gained insights into the molecular principles and cellular regulation of IL-12 family biogenesis. For each of the family members, generally one subunit depends on its partner to acquire its native structure and be secreted from immune cells. If unpaired, molecular chaperones retain these subunits in cells. This allows cells to regulate and control secretion of the highly potent IL-12 family cytokines. Molecular insights gained into IL-12 family biogenesis, structure, and function now allow us to engineer IL-12 family cytokines to develop novel immunotherapeutic approaches.

ERp44 is required for endocardial cushion development by regulating VEGFA secretion in myocardium

OBJECTIVES

Endocardial cushions are precursors of the valve septum complex that separates the four heart chambers. Several genes have been implicated in the development of endocardial cushions. Specifically, ERp44 has been found to play a role in the early secretory pathway, but its function in heart development has not been well studied.

MATERIALS AND METHODS

In this study, we established conditional and tissue-specific knockout mouse models. The morphology, survival rate, the development of heart and endocardial cushion were under evaluation. The relationship between ERp44 and VEGFA was investigated by transcriptome, qPCR, WB, immunofluorescence and immunohistochemistry.

RESULTS

ERp44 knockout (KO) mice were smaller in size, and most mice died during early postnatal life. KO hearts exhibited the typical phenotypes of congenital heart diseases, such as abnormal heart shapes and severe septal and valvular defects. Similar phenotypes were found in cTNT-Cre+/- ; ERp44fl / fl mice, which indicated that myocardial ERp44 principally controls endocardial cushion formation. Further studies demonstrated that the deletion of ERp44 significantly decreased the proliferation of cushion cells and impaired the endocardial-mesenchymal transition (EndMT), which was followed by endocardial cushion dysplasia. Finally, we found that ERp44 was directly bound to VEGFA and controlled its release, further regulating EndMT.

CONCLUSION

We demonstrated that ERp44 plays a specific role in heart development. ERp44 contributes to the development of the endocardial cushion by affecting VEGFA-mediated EndMT.

ERp44/CG9911 promotes fat storage in Drosophila adipocytes by regulating ER Ca2+ homeostasis

Fat storage is one of the important strategies employed in regulating energy homeostasis. Impaired lipid storage causes metabolic disorders in both mammals and Drosophila. In this study, we report CG9911, the Drosophila homolog of ERp44 (endoplasmic reticulum protein 44) plays a role in regulating adipose tissue fat storage. Using the CRISPR/Cas9 system, we generated a CG9911 mutant line deleting 5 bp of the coding sequence. The mutant flies exhibit phenotypes of lower bodyweight, fewer lipid droplets, reduced TAG level and increased expression of lipolysis related genes. The increased lipolysis phenotype is enhanced in the presence of ER stresses and suppressed by a reduction of the ER Ca²⁺. Moreover, loss of CG9911 per se results in a decrease of ER Ca²⁺ in the fat body. Together, our results reveal a novel function of CG9911 in promoting fat storage via regulating ER Ca²⁺ signal in Drosophila.

The pivotal role of ERp44 in patrolling protein secretion

Interactions between protein ligands and receptors are the main language of intercellular communication; hence, how cells select proteins to be secreted or presented on the plasma membrane is a central concern in cell biology. A series of checkpoints are located along the secretory pathway, which ensure the fidelity of such protein signals (quality control). Proteins that pass the checkpoints operated in the endoplasmic reticulum (ER) by the binding immunoglobulin protein (BiP; also known as HSPA5 and GRP78) and the calnexin-calreticulin systems, must still overcome additional scrutiny in the ER-Golgi intermediate compartment (ERGIC) and the Golgi. One of the main players of this process in all metazoans is the ER-resident protein 44 (ERp44); by cycling between the ER and the Golgi, ERp44 controls the localization of key enzymes designed to act in the ER but that are devoid of suitable localization motifs. ERp44 also patrols the secretion of correctly assembled disulfide-linked oligomeric proteins. Here, we discuss the mechanisms driving ERp44 substrate recognition, with important consequences on the definition of 'thiol-mediated quality control'. We also describe how pH and zinc gradients regulate the functional cycle of ERp44, coupling quality control and membrane trafficking along the early secretory compartment.

The molecular mechanisms of celecoxib in tumor development

BACKGROUND

Clinical studies have shown that celecoxib can significantly inhibit the development of tumors, and basic experiments and in vitro experiments also provide a certain basis, but it is not clear how celecoxib inhibits tumor development in detail.

METHODS

A literature search of all major academic databases was conducted (PubMed, China National Knowledge Internet (CNKI), Wan-fang, China Science and Technology Journal Database (VIP), including the main research on the mechanisms of celecoxib on tumors.

RESULTS

Celecoxib can intervene in tumor development and reduce the formation of drug resistance through multiple molecular mechanisms.

CONCLUSION

Celecoxib mainly regulates the proliferation, migration, and invasion of tumor cells by inhibiting the cyclooxygenases-2/prostaglandin E2 signal axis and thereby inhibiting the phosphorylation of nuclear factor-κ-gene binding, Akt, signal transducer and activator of transcription and the expression of matrix metalloproteinase 2 and matrix metalloproteinase 9. Meanwhile, it was found that celecoxib could promote the apoptosis of tumor cells by enhancing mitochondrial oxidation, activating mitochondrial apoptosis process, promoting endoplasmic reticulum stress process, and autophagy. Celecoxib can also reduce the occurrence of drug resistance by increasing the sensitivity of cancer cells to chemotherapy drugs.

Celecoxib enhances the sensitivity of non-small-cell lung cancer cells to radiation-induced apoptosis through downregulation of the Akt/mTOR signaling pathway and COX-2 expression

The current study aimed to identify the radiosensitizing effect of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, in combination with radiotherapy in non-small-cell lung cancer (NSCLC) cells. The combination of celecoxib potentiated radiation-induced apoptosis; however, no changes in cell cycle distribution and number of phosphorylated histone H2AX foci were detected, indicating a DNA damage-independent mechanism. In an in vivo mouse model, the tumor size was significantly decreased in the group combining celecoxib with radiation compared with the radiation only group. Phosphorylation of protein kinase B (Akt) and mammalian target of rapamycin (mTOR), as well as expression of COX-2 were significantly downregulated in cells treated with the combination of celecoxib and radiation compared with the radiation only group. The result indicated that celecoxib exhibits radiosensitizing effects through COX-2 and Akt/mTOR-dependent mechanisms. Induction the Akt/mTOR signaling pathway promotes radioresistance in various cancers, including NSCLC. Therefore, the current study suggested the therapeutic potential of combination therapy of celecoxib and radiation in the prevention of radioresistance.

Ophthalmic Nonsteroidal Anti-Inflammatory Drugs as a Therapy for Corneal Dystrophies Caused by SLC4A11 Mutation

Purpose

SLC4A11 is a plasma membrane protein of corneal endothelial cells. Some mutations of the SLC4A11 gene result in SLC4A11 protein misfolding and failure to mature to the plasma membrane. This gives rise to some cases of Fuchs' endothelial corneal dystrophy (FECD) and congenital hereditary endothelial dystrophy (CHED). We screened ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs) for their ability to correct SLC4A11 folding defects.

Methods

Five ophthalmic NSAIDs were tested for their therapeutic potential in some genetic corneal dystrophy patients. HEK293 cells expressing CHED and FECD-causing SLC4A11 mutants were grown on 96-well dishes in the absence or presence of NSAIDs. Ability of NSAIDs to correct mutant SLC4A11 cell-surface trafficking was assessed with a bioluminescence resonance energy transfer (BRET) assay and by confocal microscopy. The ability of mutant SLC4A11-expressing cells to mediate water flux (SLC4A11 mediates water flux across the corneal endothelial cell basolateral membrane as part of the endothelial water pump) was measured upon treatment with ophthalmic NSAIDs.

Results

BRET-assays revealed significant rescue of SLC4A11 mutants to the cell surface by 4 of 5 NSAIDs tested. The NSAIDs, diclofenac and nepafenac, were effective in moving endoplasmic reticulum-retained missense mutant SLC4A11 to the cell surface, as measured by confocal immunofluorescence. Among intracellular-retained SLC4A11 mutants, 20 of 30 had significant restoration of cell surface abundance upon treatment with diclofenac. Diclofenac restored mutant SLC4A11 water flux activity to the level of wild-type SLC4A11 in some cases.

Conclusions

These results encourage testing diclofenac eye drops as a treatment for corneal dystrophy in patients whose disease is caused by some SLC4A11 missense mutations.

IL-33 facilitates proliferation of colorectal cancer dependent on COX2/PGE2

Background

Interleukin-33 (IL-33) participates in various types of diseases including cancers. Previous studies of this cytokine in cancers mainly focused on its regulation on immune responses by which IL-33 modulated cancer progression. The IL-33 triggered signals in cancer cells remain unclear.

Methods

We analyzed IL-33 gene expression in human colorectal cancer (CRC) tissues and carried out gene enrichment analysis with TCGA Data Portal. We studied CRC proliferation in vivo by inoculating MC38 tumors in IL-33 transgenic mice. We investigated the cell proliferation in vitro with primary CRC cells isolated from fresh human CRC tissues, human CRC cell line HT-29 and mouse CRC cell line MC38. To evaluate the proliferation modulating effects of recombinant IL-33 incubation and other administrated factors, we measured tumor growth, colony formation, cell viability, and the expression of Ki67 and proliferating cell nuclear antigen (PCNA). We used several inhibitors, prostaglandin E2 (PGE₂) neutralizing antibody, ST2 blocking antibody and specific shRNA expressing plasmid to study the pathway mediating IL-33-induced CRC proliferation. The IL-33 receptor ST2 in human CRC tissues was detected by immunohistochemistry staining and western blotting. The ST2-positive or negative subsets of primary CRC cells were acquired by flow cytometry sorting.

Results

We found that IL-33 expression was correlated with the gene signature of cell proliferation in 394 human CRC samples. The MC38 tumors grew more rapidly and the tumor Ki67 and PCNA were expressed at higher levels in IL-33 transgenic mice than in wild-type mice. IL-33 promoted cell growth, colony formation and expression of Ki67 and PCNA in primary CRC cells as well as CRC cell lines. IL-33 activated cycloxygenase-2 (COX2) expression and increased PGE₂ production, whereas the COX2 selective inhibitor and PGE₂ neutralizing antibody abolished the proliferation promoting effect of IL-33. ST2 blockade, ST2-negative sorting, NF-κB specific inhibitor and NF-κB specific shRNA (shP65) abrogated the COX2 induction caused by IL-33.

Conclusion

IL-33 facilitates proliferation of colorectal cancer dependent on COX2/PGE₂. IL-33 functions via its receptor ST2 and upregulates COX2 expression through NF-κB signaling. Understanding the IL-33 signal transduction in CRC cells provides potential therapeutic targets for clinical treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0839-7) contains supplementary material, which is available to authorized users.

Crystal Structure of the ERp44-Peroxiredoxin 4 Complex Reveals the Molecular Mechanisms of Thiol-Mediated Protein Retention

ERp44 controls the localization and transport of diverse proteins in the early secretory pathway. The mechanisms that allow client recognition and the source of the oxidative power for forming intermolecular disulfides are as yet unknown. Here we present the structure of ERp44 bound to a client, peroxiredoxin 4. Our data reveal that ERp44 binds the oxidized form of peroxiredoxin 4 via thiol-disulfide interchange reactions. The structure explains the redox-dependent recognition and characterizes the essential non-covalent interactions at the interface. The ERp44-Prx4 covalent complexes can be reduced by glutathione and protein disulfide isomerase family members in the ER, allowing the two components to recycle. This work provides insights into the mechanisms of thiol-mediated protein retention and indicates the key roles of ERp44 in this biochemical cycle to optimize oxidative folding and redox homeostasis.

Proteostasis and "redoxtasis" in the secretory pathway: Tales of tails from ERp44 and immunoglobulins

In multicellular organisms, some cells are given the task of secreting huge quantities of proteins. To comply with their duty, they generally equip themselves with a highly developed endoplasmic reticulum (ER) and downstream organelles in the secretory pathway. These professional secretors face paramount proteostatic challenges in that they need to couple efficiency and fidelity in their secretory processes. On one hand, stringent quality control (QC) mechanisms operate from the ER onward to check the integrity of the secretome. On the other, the pressure to secrete can be overwhelming, as for instance on antibody-producing cells during infection. Maintaining homeostasis is particularly hard when the products to be released contain disulfide bonds, because oxidative folding entails production of reactive oxygen species. How are redox homeostasis ("redoxtasis") and proteostasis maintained despite the massive fluxes of cargo proteins traversing the pathway? Here we describe recent findings on how ERp44, a multifunctional chaperone of the secretory pathway, can modulate these processes integrating protein QC, redoxtasis, and calcium signaling.

A trifluoromethyl analogue of celecoxib exerts beneficial effects in neuroinflammation

Celecoxib is a selective cyclooxygenase-2 (COX2) inhibitor. We have previously shown that celecoxib inhibits experimental autoimmune encephalomyelitis (EAE) in COX-2-deficient mice, suggestive for a mode of action involving COX2-independent pathways. In the present study, we tested the effect of a trifluoromethyl analogue of celecoxib (TFM-C) with 205-fold lower COX-2 inhibitory activity in two models of neuroinflammation, i.e. cerebellar organotypic cultures challenged with LPS and the EAE mouse model for multiple sclerosis. TFM-C inhibited secretion of IL-1β, IL-12 and IL-17, enhanced that of TNF-α and RANTES, reduced neuronal axonal damage and protected from oxidative stress in the organotypic model. TFM-C blocked TNF-α release in microglial cells through a process involving intracellular retention, but induced TNF-α secretion in primary astrocyte cultures. Finally, we demonstrate that TFM-C and celecoxib ameliorated EAE with equal potency. This coincided with reduced secretion of IL-17 and IFN-γ by MOG-reactive T-cells and of IL-23 and inflammatory cytokines by bone marrow-derived dendritic cells. Our study reveals that non-coxib analogues of celecoxib may have translational value in the treatment of neuro-inflammatory conditions.

Do reciprocal interactions between cell stress proteins and cytokines create a new intra-/extra-cellular signalling nexus?

Cytokine biology began in the 1950s, and by 1988, a large number of cytokines, with a myriad of biological actions, had been discovered. In 1988, the basis of the protein chaperoning function of the heat shock, or cell stress, proteins was identified, and it was assumed that this was their major activity. However, since this time, evidence has accumulated to show that cell stress proteins are secreted by cells and can stimulate cellular cytokine synthesis with the generation of pro- and/or anti-inflammatory cytokine networks. Cell stress can also control cytokine synthesis, and cytokines are able to induce, or even inhibit, the synthesis of selected cell stress proteins and may also promote their release. How cell stress proteins control the formation of cytokines is not understood and how cytokines control cell stress protein synthesis depends on the cellular compartment experiencing stress, with cytoplasmic heat shock factor 1 (HSF1) having a variety of actions on cytokine gene transcription. The endoplasmic reticulum unfolded protein response also exhibits a complex set of behaviours in terms of control of cytokine synthesis. In addition, individual intracellular cell stress proteins, such as Hsp27 and Hsp90, have major roles in controlling cellular responses to cytokines and in controlling cytokine synthesis in response to exogenous factors. While still confusing, the literature supports the hypothesis that cell stress proteins and cytokines may generate complex intra- and extra-cellular networks, which function in the control of cells to external and internal stressors and suggests the cell stress response as a key parameter in cytokine network generation and, as a consequence, in control of immunity.

Endoplasmic reticulum stress: its role in disease and novel prospects for therapy

The endoplasmic reticulum (ER) is a multifunctional organelle required for lipid biosynthesis, calcium storage, and protein folding and processing. A number of physiological and pathological conditions, as well as a variety of pharmacological agents, are able to disturb proper ER function and thereby cause ER stress, which severely impairs protein folding and therefore poses the risk of proteotoxicity. Specific triggers for ER stress include, for example, particular intracellular alterations (e.g., calcium or redox imbalances), certain microenvironmental conditions (e.g., hypoglycemia, hypoxia, and acidosis), high-fat and high-sugar diet, a variety of natural compounds (e.g., thapsigargin, tunicamycin, and geldanamycin), and several prescription drugs (e.g., bortezomib/Velcade, celecoxib/Celebrex, and nelfinavir/Viracept). The cell reacts to ER stress by initiating a defensive process, called the unfolded protein response (UPR), which is comprised of cellular mechanisms aimed at adaptation and safeguarding cellular survival or, in cases of excessively severe stress, at initiation of apoptosis and elimination of the faulty cell. In recent years, this dichotomic stress response system has been linked to several human diseases, and efforts are underway to develop approaches to exploit ER stress mechanisms for therapy. For example, obesity and type 2 diabetes have been linked to ER stress-induced failure of insulin-producing pancreatic beta cells, and current research efforts are aimed at developing drugs that ameliorate cellular stress and thereby protect beta cell function. Other studies seek to pharmacologically aggravate chronic ER stress in cancer cells in order to enhance apoptosis and achieve tumor cell death. In the following, these principles will be presented and discussed.

A 4-trifluoromethyl analogue of celecoxib inhibits arthritis by suppressing innate immune cell activation

Introduction

Celecoxib, a highly specific cyclooxygenase-2 (COX-2) inhibitor has been reported to have COX-2-independent immunomodulatory effects. However, celecoxib itself has only mild suppressive effects on arthritis. Recently, we reported that a 4-trifluoromethyl analogue of celecoxib (TFM-C) with 205-fold lower COX-2-inhibitory activity inhibits secretion of IL-12 family cytokines through a COX-2-independent mechanism that involves Ca²⁺-mediated intracellular retention of the IL-12 polypeptide chains. In this study, we explored the capacity of TFM-C as a new therapeutic agent for arthritis.

Methods

To induce collagen-induced arthritis (CIA), DBA1/J mice were immunized with bovine type II collagen (CII) in Freund's adjuvant. Collagen antibody-induced arthritis (CAIA) was induced in C57BL/6 mice by injecting anti-CII antibodies. Mice received 10 μg/g of TFM-C or celecoxib every other day. The effects of TFM-C on clinical and histopathological severities were assessed. The serum levels of CII-specific antibodies were measured by ELISA. The effects of TFM-C on mast cell activation, cytokine producing capacity by macophages, and neutrophil recruitment were also evaluated.

Results

TFM-C inhibited the severity of CIA and CAIA more strongly than celecoxib. TFM-C treatments had little effect on CII-specific antibody levels in serum. TFM-C suppressed the activation of mast cells in arthritic joints. TFM-C also suppressed the production of inflammatory cytokines by macrophages and leukocyte influx in thioglycollate-induced peritonitis.

Conclusion

These results indicate that TFM-C may serve as an effective new disease-modifying drug for treatment of arthritis, such as rheumatoid arthritis.

ERp44 C160S/C212S mutants regulate IP3R1 channel activity

Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate (IP(3))-induced Ca(2+) release (IICR) via IP(3)R(1), but the mechanism remains largely unexplored. Using extracellular ATP to induce intracellular calcium transient as an IICR model, Ca(2+) image, pull down assay, and Western blotting experiments were carried out in the present study. We found that extracellular ATP induced calcium transient via IP(3)Rs (IICR) and the IICR were markedly decreased in ERp44 overexpressed Hela cells. The inhibitory effect of C160S/C212S but not C29S/T396A/ΔT(331-377) mutants of ERp44 on IICR were significantly decreased compared with ERp44. However, the binding capacity of ERp44 to L3V domain of IP(3)R(1) (1L3V) was enhanced by ERp44 C160S/C212S mutation. Taken together, these results suggest that the mutants of ERp44, C160/C212, can more tightly bind to IP(3)R(1) but exhibit a weak inhibition of IP(3)R(1) channel activity in Hela cells.

Molecular cloning and characterization of the porcine Ero1L and ERp44 genes: potential roles in controlling energy metabolism

Disulfide bond formation is a pivotal step in the maturation and release of secretory proteins that is controlled by specific endoplasmic reticulum (ER) resident enzymes. An important element in this process is Ero (ER oxidoreduction), a glycosylated flavoenzyme tightly associated with oxidative protein folding that lacks the known ER retention motifs. ER resident protein 44kDa (ERp44) is an ER resident protein that mediates ERo1 localization in ER and also prevents the secretion of unassembled cargo proteins with unpaired cysteine. These proteins are not only the key participants in the disulfide-bond formation process, but they also control the secretory pathway on both qualitative and quantitative levels. Here, we cloned full-length cDNA sequences of the porcine Ero1L (1448bp) and ERp44 (1361bp) genes. Isolation and characterization of their genomic sequences revealed that Ero1L contains 16 exons and 15 introns almost 150 kp in length, whereas ERp44 contains 12 exons and 11 introns more than 140 kp in length, and they are located on porcine chromosome 1q21 and 1q29, respectively. Tissue distribution analysis of the two genes revealed extremely high expression in adipose tissue, and the topology of their phylogenic tree indicates a high degree of conservation among different species. We looked at transcription factors binding sites in the 5'-flanking regions of Ero1L and ERp44, and many adipose differentiations related factors reflect the tight relationship to energy metabolism.

The endoplasmic reticulum protein folding factory and its chaperones: new targets for drug discovery?

Cytosolic heat shock proteins have received significant attention as emerging therapeutic targets. Much of this excitement has been triggered by the discovery that HSP90 plays a central role in the maintenance and stability of multifarious oncogenic membrane receptors and their resultant tyrosine kinase activity. Numerous studies have dealt with the effects of small molecules on chaperone- and stress-related pathways of the endoplasmic reticulum (ER). However, unlike cytosolic chaperones, relatively little emphasis has been placed upon translational avenues towards targeting of the ER for inhibition of folding/secretion of disease-promoting proteins. Here, we summarise existing small molecule inhibitors and potential future targets of ER chaperone-mediated inhibition. Client proteins of translational relevance in disease treatment are outlined, alongside putative future disease treatment modalities based on ER-centric targeted therapies. Particular attention is paid to cancer and autoimmune disorders via the effects of the GRP94 inhibitor geldanamycin and its population of client proteins, overloading of the unfolded protein response, and inhibition of members of the IL-12 family of cytokines by celecoxib and non-coxib analogues.

Inhibiting ERp29 expression enhances radiosensitivity in human nasopharyngeal carcinoma cell lines

ERp29 is an endoplasmic reticulum (ER) stress-inducible protein. It was found that ERp29 was highly expressed in several cancers and associated with resistance to oxidative and radiation stress, which may serve as a novel target for nasopharyngeal carcinoma (NPC) anticancer approach. In this study, we used immunohistochemistry to detect ERp29 expression in radioresistant and radiosensitive NPC tissues. As a result, ERp29 was up-regulated in radioresistant NPC tissues compared to radiosensitive NPC tissues. We also found that ERp29 knockdown attenuated radioresistance of NPC CNE-1 cells and ERp29 overexpression enhanced radioresistance of NPC CNE-2 cells. When exposed to radiation, ERp29 knockdown CNE-1 cells increased radiation-induced cell apoptosis and ERp29 overexpression CNE-2 cells reduced radiation-induced cell apoptosis. Further, we demonstrated that ERp29 up-regulated the expression of Hsp27. In conclusion, our study supports ERp29 could potentiate resistance to radiation in NPC cells, targeting of ERp29 is a rational strategy in treating radioresistant NPC.

Targeting apoptosis pathways by Celecoxib in cancer

Celecoxib is a paradigmatic selective inhibitor of cyclooxygenase-2 (COX-2). This anti-inflammatory drug has potent anti-tumor activity in a wide variety of human epithelial tumor types, such as colorectal, breast, non-small cell lung, and prostate cancers. Up to now, the drug found application in cancer prevention in patients with familial adenomatous polyposis. Moreover, the use of Celecoxib is currently tested in the prevention and treatment of pancreatic, breast, ovarian, non-small cell lung cancer and other advanced human epithelial cancers. Induction of apoptosis contributes to the anti-neoplastic activity of Celecoxib. In most cellular systems Celecoxib induces apoptosis independently from its COX-2 inhibitory action via a mitochondrial apoptosis pathway which is however, not inhibited by overexpression of Bcl-2. In addition, Celecoxib exerts antagonistic effects on the anti-apoptotic proteins Mcl-1 and survivin. Consequently, the use of Celecoxib may be of specific value for the treatment of apoptosis-resistant tumors with overexpression of Bcl-2, Mcl-1, or survivin as single drug or in combination with radiotherapy, chemotherapy, or targeted pro-apoptotic drugs that are inhibited by survivin, Bcl-2 or Mcl-1. As COX-2 inhibition has been associated with cardiovascular toxicity, the value of drug derivatives without COX-2 inhibitory action should be validated for prevention and treatment of human epithelial tumors to reduce the risk for heart attack or stroke. However, its additional COX-2 inhibitory action may qualify Celecoxib for a cautious use in COX-2-dependent epithelial tumors, where the drug could additionally suppress COX-2-mediated growth and survival promoting signals from the tumor and the stromal cells.

Non-Steroidal Anti-Inflammatory Drugs, Variation in Inflammatory Genes, and Aggressive Prostate Cancer

Increasing evidence suggests that prostatic inflammation plays a key role in the development of prostate cancer. It remains controversial whether non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of prostate cancer. Here, we investigate how a previously reported inverse association between NSAID use and the risk of aggressive prostate cancer is modulated by variants in several inflammatory genes. We found that NSAIDs may have differential effects on prostate cancer development, depending on one’s genetic makeup. Further study of these inflammatory pathways may clarify the mechanisms through which NSAIDs impact prostate cancer risk.

From antibodies to adiponectin: role of ERp44 in sizing and timing protein secretion

A large fraction of the proteome is synthesized and folded in the endoplasmic reticulum (ER), a multifunctional compartment also playing pivotal roles in Ca(2+) storage, redox homeostasis and signalling. From the ER, secretory proteins begin their journey towards their final destinations, the organelles of the exocytic and endocytic compartments, the plasma membrane or the extracellular space. Fidelity of protein-based intracellular communication is guaranteed by quality control (QC) mechanisms located at the ER-Golgi interface, which restrict forward transport to native proteins. QC is used also to time or shape the secretome. Furthermore, professional secretory cells face a problem of quantity, as well as quality of their protein products. This essay summarizes recent findings that identify ERp44 as a key regulator of protein secretion, Ca(2+) signalling and redox regulation.

Inhibition of secretion of interleukin (IL)-12/IL-23 family cytokines by 4-trifluoromethyl-celecoxib is coupled to degradation via the endoplasmic reticulum stress protein HERP

Interleukin-12 (IL-12), p80, and IL-23 are structurally related cytokines sharing a p40 subunit. We have recently demonstrated that celecoxib and its COX-2-independent analogue 4-trifluoromethyl-celecoxib (TFM-C) inhibit secretion but not transcription of IL-12 (p35/p40) and p80 (p40/p40). This is associated with a mechanism involving altered cytokine-chaperone interaction in the endoplasmic reticulum (ER). In the present study, we found that celecoxib and TFM-C also block secretion of IL-23 (p40/p19 heterodimers). Given the putative ER-centric mode of these compounds, we performed a comprehensive RT-PCR analysis of 23 ER-resident chaperones/foldases and associated co-factors. This revealed that TFM-C induced 1.5-3-fold transcriptional up-regulation of calreticulin, GRP78, GRP94, GRP170, ERp72, ERp57, ERdj4, and ERp29. However, more significantly, a 7-fold up-regulation of homocysteine-inducible ER protein (HERP) was observed. HERP is part of a high molecular mass protein complex involved in ER-associated protein degradation (ERAD). Using co-immunoprecipitation assays, we show that TFM-C induces protein interaction of p80 and IL-23 with HERP. Both HERP siRNA knockdown and HERP overexpression coupled to cycloheximide chase assays revealed that HERP is necessary for degradation of intracellularly retained p80 by TFM-C. Thus, our data suggest that targeting cytokine folding in the ER by small molecule drugs could be therapeutically exploited to alleviate inappropriate inflammation in autoimmune conditions.

Genetic disruption of cyclooxygenase-2 does not improve histological or behavioral outcome after traumatic brain injury in mice

Increasing evidence suggests a role for cyclooxygenase-2 (COX-2) in traumatic brain injury (TBI). In the present study, the role of COX-2 in TBI was investigated using COX-2 gene-disrupted (COX-2 null) mice and wild-type (WT) controls that were subjected to the controlled cortical impact (CCI) model of TBI. There was increased expression of COX-2 in ipsilateral hippocampus in WT mice subjected to CCI. CCI resulted in a significant increase in prostaglandin E(2) concentrations in WT compared with COX-2 null hippocampi. There was a significant increase in TUNEL staining of CA1 neurons 24 hr after CCI in WT, but not in COX-2 null mice, compared with sham-operated controls, which is consistent with a protective role for COX-2 in the early phase of injury after TBI. However, there was no difference in lesion volume 21 days after CCI in COX-2 null and WT mice. COX-2 gene disruption did not alter Morris water maze performance. Taken together, these results suggest only a minor role for COX-2 activity in determining outcome after TBI in mouse.

Mechanisms of drug combinations: interaction and network perspectives

Understanding the molecular mechanisms underlying synergistic, potentiative and antagonistic effects of drug combinations could facilitate the discovery of novel efficacious combinations and multi-targeted agents. In this article, we describe an extensive investigation of the published literature on drug combinations for which the combination effect has been evaluated by rigorous analysis methods and for which relevant molecular interaction profiles of the drugs involved are available. Analysis of the 117 drug combinations identified reveals general and specific modes of action, and highlights the potential value of molecular interaction profiles in the discovery of novel multicomponent therapies.

NOD2/CARD15 genotype influences MDP-induced cytokine release and basal IL-12p40 levels in primary isolated peripheral blood monocytes

BACKGROUND

The functional link between mutations in NOD2 and Crohn's disease (CD) has not been entirely elucidated. The 1007fs mutation results in loss of NF-kappaB activation in response to muramyl dipeptide (MDP) but has also been linked to an increased IL-1beta processing and IL-12 release.

METHODS

We investigated the basal and MDP-triggered mRNA expression and protein release for TNF-alpha, IL-10, IL-1beta, and IL-12p40 in peripheral blood monocytes from 40 CD patients and 15 healthy individuals with different NOD2 genotypes.

RESULTS

Monocytes from individuals with 2 mutated NOD2 alleles (homozygous and compound-heterozygous individuals) displayed an impaired release of TNF-alpha and IL-10 but also of IL-1beta and IL-12p40 in response to MDP. In contrast to other NOD2 variants, the presence of at least 1 1007fs allele in double-mutated individuals completely abrogated NOD2 receptor function. Interestingly, monocytes from CD patients with 2 mutated NOD2 alleles displayed significantly higher basal levels of IL-12p40 in cell culture supernatants compared to wildtype CD patients and control individuals (P = 0.002 and P = 0.008, respectively). This was regardless of the IL23R genotype and was not mirrored by increased IL-12p40 plasma levels in these individuals.

CONCLUSIONS

The CD-associated NOD2 variants lead, in a dose- and mutation-dependent manner, to an impaired release of TNF-alpha, IL-10, IL-1beta, and IL-12p40 in response to MDP. The finding of increased basal levels for IL-12p40-related cytokines in monocytes with 2 mutated NOD2 alleles is likely to set a new link between NOD2 mutations and the inflammatory mechanisms underlying CD.

Triplex profiling of functionally distinct chaperones (ERp29/PDI/BiP) reveals marked heterogeneity of the endoplasmic reticulum proteome in cancer

The biomedical need for streamlined approaches to monitor proteome dynamics is growing rapidly. This study examined the ability of a knowledge-based triplex-profiling strategy (i.e., three functionally distinct chaperones, ERp29/PDI/BiP) to clarify uncertainties about how cancer affects the endoplasmic reticulum (ER) proteome. Investigating a wide range of samples at the tissue and cellular levels (>114 samples from 9 tissues of origin), we obtained consistent evidence that the ER proteome undergoes a major but variable expansion in cancer. Three factors having a strong influence on the ER proteome were identified (cancer-cell type, growth rate, culture mode), and the functionally enigmatic chaperone ERp29 was linked distinctively to histogenetic aspects of tumorigenesis. These findings justify pursuit of the ER-proteome as a medical target in cancer, validate ERp29/PDI/BiP profiling as a streamlined yet powerful measure of ER-proteome dynamics, and suggest that biomarker sets based on distinct functionalities could have broader biomedical utility.

COX-2 inhibition is neither necessary nor sufficient for celecoxib to suppress tumor cell proliferation and focus formation in vitro

Background

An increasing number of reports is challenging the notion that the antitumor potential of the selective COX-2 inhibitor celecoxib (Celebrex^®) is mediated primarily via the inhibition of COX-2. We have investigated this issue by applying two different analogs of celecoxib that differentially display COX-2-inhibitory activity: the first analog, called unmethylated celecoxib (UMC), inhibits COX-2 slightly more potently than its parental compound, whereas the second analog, 2,5-dimethyl-celecoxib (DMC), has lost the ability to inhibit COX-2.

Results

With the use of glioblastoma and pancreatic carcinoma cell lines, we comparatively analyzed the effects of celecoxib, UMC, and DMC in various short-term (≤48 hours) cellular and molecular studies, as well as in long-term (≤3 months) focus formation assays. We found that DMC exhibited the most potent antitumor activity; celecoxib was somewhat less effective, and UMC clearly displayed the overall weakest antitumor potential in all aspects. The differential growth-inhibitory and apoptosis-stimulatory potency of these compounds in short-term assays did not at all correlate with their capacity to inhibit COX-2, but was closely aligned with their ability to trigger endoplasmic reticulum stress (ERS), as indicated by the induction of the ERS marker CHOP/GADD153 and activation of the ERS-associated caspase 7. In addition, we found that these compounds were able to restore contact inhibition and block focus formation during long-term, chronic drug exposure of tumor cells, and this was achieved at sub-toxic concentrations in the absence of ERS or inhibition of COX-2.

Conclusion

The antitumor activity of celecoxib in vitro did not involve the inhibition of COX-2. Rather, the drug's ability to trigger ERS, a known effector of cell death, might provide an alternative explanation for its acute cytotoxicity. In addition, the newly discovered ability of this drug to restore contact inhibition and block focus formation during chronic drug exposure, which involved neither ERS nor COX-2, suggests a novel, as yet unrecognized mechanism of celecoxib action.

Celecoxib analogs that lack COX-2 inhibitory function: preclinical development of novel anticancer drugs

Celecoxib is an NSAID that was developed as a selective inhibitor of COX-2 and approved by the FDA for the treatment of various forms of arthritis and the management of acute or chronic pain. In addition, it was more recently approved as an oral adjunct to prevent colon cancer development in patients with familial adenomatous polyposis and is presently being investigated for its chemotherapeutic potential in the therapy of advanced cancers. However, in laboratory studies it was discovered that celecoxib was able to suppress tumor growth in the absence of any apparent involvement of COX-2, and additional pharmacologic activities associated with this drug were found. Intriguingly, the two pharmacologic effects, inhibition of COX-2 and suppression of tumor growth, were found to reside in different structural aspects of the celecoxib molecule and, therefore, could be separated. This dualism enabled the synthesis of close structural analogs of celecoxib that exhibited increased antitumor potency in the absence of COX-2 inhibition. In theory, such compounds should be superior to celecoxib for antitumor purposes because they might reduce gastrointestinal and cardiovascular risks and the life-threatening side effects that appear during the long-term use of selective COX-2 inhibitors. In this review, the authors present the status of preclinical development of anticancer analogs of celecoxib that are COX-2 inactive, with an emphasis on 2,5-dimethyl-celecoxib (DMC) and OSU-03012.

Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) selectivity of COX inhibitors

In vitro evaluations of the selectivity of COX inhibitors are based on a great variety of experimental protocols. As a result, data available on cyclooxygenase (COX)-1/COX-2/5- lipoxygenase (LOX) selectivity of COX inhibitors lack consistency. We, therefore, performed a systematic analysis of the COX-1/COX-2/5-LOX selectivity of 14 compounds with selective COX inhibitory activity (Coxibs). The compounds belonged to different structural classes and were analyzed employing the well-recognized whole-blood assay. 5-LOX activity was also tested on isolated human polymorphonuclear leukocytes. Among COX inhibitors, celecoxib and ML-3000 (licofelone) inhibited 5-LOX in human neutrophils at micromolar ranges. Surprisingly, ML-3000 had no effect on 5-LOX product synthesis in whole-blood assay. In addition, we could show that inhibition of COX pathways did not increase the transformation of arachidonic acid by the 5-LOX pathway.

Direct non-cyclooxygenase-2 targets of celecoxib and their potential relevance for cancer therapy

Celecoxib (Celebrex®) was developed as a selective cyclooxygenase-2 (COX-2) inhibitor for the treatment of chronic pain. However, it now appears that this compound harbours additional pharmacologic activities that are entirely independent of its COX-2-inhibitory activity. This review presents the recently emerged direct non-COX-2 targets of celecoxib and their proposed role in mediating this drug's antitumour effects.

Effects of celecoxib on voltage-gated calcium channel currents in rat pheochromocytoma (PC12) cells

Cyclooxygenase-2 (COX-2) plays crucial roles in the development and invasion of tumors. Celecoxib, a selective COX-2 inhibitor, has been shown to be chemopreventive against cancer. However, to date, the mechanisms of these effects remain unclear. In this study, we investigate the effects of celecoxib on voltage-gated calcium channel (VGCC) currents in undifferentiated pheochromocytoma (PC12) cells using whole-cell patch clamp. Our results showed that celecoxib, instead of rofecoxib or NS-398, another selective COX-2 inhibitor, reversibly inhibited the current density of VGCC in a concentration-dependent manner, but had no apparent effects on the cells treated with nifedipine (1 microM), an L-type calcium channel blocker. Upon pre-incubation of PC12 cells with omega-conotoxia GVIA (1 microM), an N-type calcium channel blocker, omega-agatoxin IVA (1microM), a P/Q-type calcium channel blocker, or SNX-482 (1microM), a R-type calcium channel blocker, celecoxib (1microM) inhibited the currents by 36%, 28%, and 25%, respectively. Celecoxib up-shifted the current-voltage (I-V), and hyperpolarizedly shifted the inactivation curve, but did not markedly affect the activation curve. Intracellular application of H89, a protein kinase A inhibitor, failed to affect the celecoxib's VGCC currents inhibition. Taken together, our present results suggested that celecoxib inhibited L-type calcium channels in PC12 cells via a COX-2 independent pathway, which might be responsible for its clinical effects including anti-tumor.