Involvement of intracellular Ca2+ levels in nonsteroidal anti-inflammatory drug-induced apoptosis

Integrated analysis of gut metabolome, microbiome, and exfoliome data in an equine model of intestinal injury

BACKGROUND

The equine gastrointestinal (GI) microbiome has been described in the context of various diseases. The observed changes, however, have not been linked to host function and therefore it remains unclear how specific changes in the microbiome alter cellular and molecular pathways within the GI tract. Further, non-invasive techniques to examine the host gene expression profile of the GI mucosa have been described in horses but not evaluated in response to interventions. Therefore, the objectives of our study were to (1) profile gene expression and metabolomic changes in an equine model of non-steroidal anti-inflammatory drug (NSAID)-induced intestinal inflammation and (2) apply computational data integration methods to examine host-microbiota interactions.

METHODS

Twenty horses were randomly assigned to 1 of 2 groups (n = 10): control (placebo paste) or NSAID (phenylbutazone 4.4 mg/kg orally once daily for 9 days). Fecal samples were collected on days 0 and 10 and analyzed with respect to microbiota (16S rDNA gene sequencing), metabolomic (untargeted metabolites), and host exfoliated cell transcriptomic (exfoliome) changes. Data were analyzed and integrated using a variety of computational techniques, and underlying regulatory mechanisms were inferred from features that were commonly identified by all computational approaches.

RESULTS

Phenylbutazone induced alterations in the microbiota, metabolome, and host transcriptome. Data integration identified correlation of specific bacterial genera with expression of several genes and metabolites that were linked to oxidative stress. Concomitant microbiota and metabolite changes resulted in the initiation of endoplasmic reticulum stress and unfolded protein response within the intestinal mucosa.

CONCLUSIONS

Results of integrative analysis identified an important role for oxidative stress, and subsequent cell signaling responses, in a large animal model of GI inflammation. The computational approaches for combining non-invasive platforms for unbiased assessment of host GI responses (e.g., exfoliomics) with metabolomic and microbiota changes have broad application for the field of gastroenterology. Video Abstract.

A dual role of lysophosphatidic acid type 2 receptor (LPAR2) in nonsteroidal anti-inflammatory drug-induced mouse enteropathy

Lysophosphatidic acid (LPA) is a bioactive phospholipid mediator that has been found to ameliorate nonsteroidal anti-inflammatory drug (NSAID)-induced gastric injury by acting on lysophosphatidic acid type 2 receptor (LPAR2). In this study, we investigated whether LPAR2 signaling was implicated in the development of NSAID-induced small intestinal injury (enteropathy), another major complication of NSAID use. Wild-type (WT) and Lpar2 deficient (Lpar2-/-) mice were treated with a single, large dose (20 or 30 mg/kg, i.g.) of indomethacin (IND). The mice were euthanized at 6 or 24 h after IND treatment. We showed that IND-induced mucosal enteropathy and neutrophil recruitment occurred much earlier (at 6 h after IND treatment) in Lpar2-/- mice compared to WT mice, but the tissue levels of inflammatory mediators (IL-1β, TNF-α, inducible COX-2, CAMP) remained at much lower levels. Administration of a selective LPAR2 agonist DBIBB (1, 10 mg/kg, i.g., twice at 24 h and 30 min before IND treatment) dose-dependently reduced mucosal injury and neutrophil activation in enteropathy, but it also enhanced IND-induced elevation of several proinflammatory chemokines and cytokines. By assessing caspase-3 activation, we found significantly increased intestinal apoptosis in IND-treated Lpar2-/- mice, but it was attenuated after DBIBB administration, especially in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. Finally, we showed that IND treatment reduced the plasma activity and expression of autotaxin (ATX), the main LPA-producing enzyme, and also reduced the intestinal expression of Lpar2 mRNA, which preceded the development of mucosal damage. We conclude that LPAR2 has a dual role in NSAID enteropathy, as it contributes to the maintenance of mucosal integrity after NSAID exposure, but also orchestrates the inflammatory responses associated with ulceration. Our study suggests that IND-induced inhibition of the ATX-LPAR2 axis is an early event in the pathogenesis of enteropathy.

Development of PET Radioligands Targeting COX-2 for Colorectal Cancer Staging, a Review of in vitro and Preclinical Imaging Studies

Colorectal cancer (CRC) is the second most common cause of cancer death, making early diagnosis a major public health challenge. The role of inflammation in tumorigenesis has been extensively explored, and among the identified markers of inflammation, cyclooxygenase-2 (COX-2) expression seems to be linked to lesions with a poor prognosis. Until now, COX-2 expression could only be accessed by invasive methods, mainly by biopsy. Imaging techniques such as functional Positron Emission Tomography (PET) could give access to in vivo COX-2 expression. This could make the staging of the disease more accurate and would be of particular interest in the exploration of the first metastatic stages. In this paper, we review recent progress in the development of COX-2 specific PET tracers by comparing the radioligands' characteristics and highlighting the obstacles that remain to be overcome in order to achieve the clinical development of such a radiotracer, and its evaluation in the management of CRC.

Benzyl isothiocyanates modulate inflammation, oxidative stress, and apoptosis via Nrf2/HO-1 and NF-κB signaling pathways on indomethacin-induced gastric injury in rats

The present study investigated the gastroprotective activity of benzyl isothiocyanates (BITC) on indomethacin (IND)-induced gastric injury in a rat model and explicated the possible involved biochemical, cellular, and molecular mechanisms. The rat model with gastric ulcers was established by a single oral dose of IND (30 mg per kg b.wt). BITC (0.75 and 1.5 mg kg^-1) and esomeprazole (20 mg per kg b.wt) were orally administered for 3 weeks to rats before the induction of gastric injury. Compared with the IND group, BITC could diminish both the macroscopic and microscopic pathological morphology of gastric mucosa. BITC significantly preserved the antioxidants (glutathione GSH, superoxide dismutase SOD), nitric oxide (NO), and prostaglandin E2 (PGE2) contents, while decreasing the gastric mucosal malondialdehyde (MDA), tumor necrosis factor alpha (TNFα), and myeloperoxidase (MPO) contents. Moreover, BITC remarkably upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), hemoxygenase-1 (HO-1), and NAD(P)H : quinone oxidoreductase (NQO1). In addition, BITC activates the expression of heat shock protein 70 (HSP-70) and downregulated the expression of nuclear factor-κB (NF-κB) and caspase-3 to promote gastric mucosal cell survival. To the best of our knowledge, this study is the first published report to implicate the suppression of inflammation, oxidative stress, and Nrf2 signaling pathway as a potential mechanism for the gastroprotective activity of BITC.

Identification of Celecoxib-Targeted Proteins Using Label-Free Thermal Proteome Profiling on Rat Hippocampus

Celecoxib, or Celebrex, a nonsteroidal anti-inflammatory drug, is one of the most common medicines for treating inflammatory diseases. Recently, it has been shown that celecoxib is associated with implications in complex diseases, such as Alzheimer disease and cancer as well as with cardiovascular risk assessment and toxicity, suggesting that celecoxib may affect multiple unknown targets. In this project, we detected targets of celecoxib within the nervous system using a label-free thermal proteome profiling method. First, proteins of the rat hippocampus were treated with multiple drug concentrations and temperatures. Next, we separated the soluble proteins from the denatured and sedimented total protein load by ultracentrifugation. Subsequently, the soluble proteins were analyzed by nano-liquid chromatography tandem mass spectrometry to determine the identity of the celecoxib-targeted proteins based on structural changes by thermal stability variation of targeted proteins toward higher solubility in the higher temperatures. In the analysis of the soluble protein extract at 67°C, 44 proteins were uniquely detected in drug-treated samples out of all 478 identified proteins at this temperature. Ras-associated binding protein 4a, 1 out of these 44 proteins, has previously been reported as one of the celecoxib off targets in the rat central nervous system. Furthermore, we provide more molecular details through biomedical enrichment analysis to explore the potential role of all detected proteins in the biologic systems. We show that the determined proteins play a role in the signaling pathways related to neurodegenerative disease-and cancer pathways. Finally, we fill out molecular supporting evidence for using celecoxib toward the drug-repurposing approach by exploring drug targets. SIGNIFICANCE STATEMENT: This study determined 44 off-target proteins of celecoxib, a nonsteroidal anti-inflammatory and one of the most common medicines for treating inflammatory diseases. It shows that these proteins play a role in the signaling pathways related to neurodegenerative disease and cancer pathways. Finally, the study provides molecular supporting evidence for using celecoxib toward the drug-repurposing approach by exploring drug targets.

Synergistic apoptosis following endoplasmic reticulum stress aggravation in mucinous colon cancer

BACKGROUND

Mucinous colon cancers (MCC) are characterized by abundant production of mucin 2 (MUC2) protein and are less sensitive to standard systemic chemotherapy. We postulated that severe/persistent endoplasmic reticulum stress (ERS) aggravation in MCC would overwhelm compensatory cytoprotective pathways and induce apoptosis.

RESULTS

Basal levels of ERS markers were higher in MCC and dnTCF-LS174T cells than non-mucinous tumors and these levels were significantly increased by combinatorial treatment with ERS aggravators celecoxib + orlistat. Combination treatment inhibited cell viability and synergistically induced apoptosis. Treatment-induced cell death was ERS-dependent, apoptotic pathways were not activated following knockdown of ERS protein CHOP. Dual drug treatment significantly reduced mucinous tumor growth in vivo and induced ERS and apoptosis, consistent with in vitro experiments.

CONCLUSIONS

Novel therapies are needed since MCC are more resistant to standard systemic chemotherapy. This study suggests ERS aggravation is a viable therapeutic strategy to reduce tumor growth in MCC.

Down-Regulation of m6A mRNA Methylation Is Involved in Dopaminergic Neuronal Death

N⁶-Methyladenosine (m6A) is the most prevalent internal modification that occurs in the mRNA of eukaryotes and plays a vital role in the post-transcriptional regulation. Recent studies highlighted the biological significance of m6A modification in the nervous system, and its dysregulation has been shown to be related to degenerative and neurodevelopmental diseases. Parkinson's disease (PD) is a common age-related neurological disorder with its pathogenesis still not fully elucidated. Reports have shown that epigenetic mechanisms including DNA methylation and histone acetylation, which alter gene expression, are associated with PD. In this study, we found that global m6A modification of mRNAs is down-regulated in 6-OHDA-induced PC12 cells and the striatum of PD rat brain. To further explore the relationship between m6A mRNA methylation and molecular mechanism of PD, we decreased m6A in dopaminergic cells by overexpressing a nucleic acid demethylase, FTO, or by m6A inhibitor. The results showed that m6A reduction could induce the expression of N-methyl-d-aspartate (NMDA) receptor 1, and elevate oxidative stress and Ca²⁺ influx, resulting in dopaminergic neuron apoptosis. Collectively, m6A modification may play a vital role in the death of dopaminergic neuron, which provides a novel view of mRNA methylation to understand the epigenetic regulation of Parkinson's disease.

Protocatechuic acid-mediated DJ-1/PARK7 activation followed by PI3K/mTOR signaling pathway activation as a novel mechanism for protection against ketoprofen-induced oxidative damage in the gastrointestinal mucosa

Oxidative stress contributes to the progression of non-steroidal anti-inflammatory drug (NSAID)-induced gastrointestinal (GI) cell apoptosis. In our previous study, we reported that nuclear factor erythroid 2-related factor 2 (Nrf2) plays a protective role against ketoprofen-induced GI mucosal oxidative injury. Recent reports suggest that Nrf2 could exhibit antioxidative and antiapoptosis responses through up-regulation of DJ-1 (PARK7). In the current study, we proposed that induction of DJ-1 expression by protocatechuic acid (PCA) might provide a potential therapeutic approach for treating oxidative stress-associated GI ulcer diseases. The results indicated that PCA increased mRNA expression of glutathione peroxidase and heme oxygenase-1 through up-regulation of DJ-1 followed by Nrf2 translocation. Furthermore, PCA protected Int-407 cells against ketoprofen-induced oxidative stress by regulating the DJ-1, PI3K, and mTOR pathways. Pretreatment with PCA inhibited mitochondrial ROS generation, up-regulated the mitochondrial membrane potential, and down-regulated pro-apoptotic Bax as well as downstream caspase-8, caspase-9, and caspase-3 activity, and reversed impaired DJ-1 and anti-apoptotic Bcl-2 protein expression in Int-407 cells induced by ketoprofen. Similar to the in vitro results, SD rats treated with PCA before administration of ketoprofen exhibited decreased caspase-3 protein expression as well as oxidative damage, and impairment of the antioxidant system and DJ-1 protein expression in the GI mucosa were reversed. The administration of lansoprazole, a type of proton pump inhibitor (PPI), strongly inhibited ketoprofen-induced GI mucosal injuries via up-regulation of DJ-1, indicating that DJ-1 is essential for the dietary antioxidant- and PPI drug-mediated mechanism of ulcer therapy. These results suggest that DJ-1 could be a novel target for protection against ketoprofen-induced GI ulcers due to its antioxidant and anti-apoptosis characteristics.

Role of non-steroidal anti-inflammatory drugs on intestinal permeability and nonalcoholic fatty liver disease

The use of non-steroidal anti-inflammatory drugs (NSAIDs) is widespread worldwide thanks to their analgesic, anti-inflammatory and antipyretic effects. However, even more attention is placed upon the recurrence of digestive system complications in the course of their use. Recent data suggests that the complications of the lower gastro-intestinal tract may be as frequent and severe as those of the upper tract. NSAIDs enteropathy is due to enterohepatic recycling of the drugs resulting in a prolonged and repeated exposure of the intestinal mucosa to the compound and its metabolites. Thus leading to so-called topical effects, which, in turn, lead to an impairment of the intestinal barrier. This process determines bacterial translocation and toxic substances of intestinal origin in the portal circulation, leading to an endotoxaemia. This condition could determine a liver inflammatory response and might promote the development of non-alcoholic steatohepatitis, mostly in patients with risk factors such as obesity, metabolic syndrome and a high fat diet, which may induce a small intestinal bacterial overgrowth and dysbiosis. This alteration of gut microbiota may contribute to nonalcoholic fatty liver disease and its related disorders in two ways: firstly causing a malfunction of the tight junctions that play a critical role in the increase of intestinal permeability, and then secondly leading to the development of insulin resistance, body weight gain, lipogenesis, fibrogenesis and hepatic oxidative stress.

A 35 kDa Phyllanthus niruri protein suppresses indomethacin mediated hepatic impairments: Its role in Hsp70, HO-1, JNKs and Ca2+ dependent inflammatory pathways

The present study has been conducted to explore a novel strategy to modulate the unfavourable effects of indomethacin by Phyllanthus niruri protein (PNP) and the underlying mechanism PNP exploits for the amelioration of that pathophysiology. In hepatocytes, indomethacin enhanced reactive oxygen species (ROS), reduced intracellular antioxidant capacity, up regulated mitogen activated protein kinase (MAPKs), disrupted mitochondrial membrane potential, activated apoptotic pathways and there by reduced the viability of the hepatocytes. Simultaneous treatment with PNP modulated these detrimental actions of the drug and retained cell viability. Similarly, in mice, indomethacin elevated serum marker enzymes (e.g. Alanine Transaminase), decreased antioxidant enzyme activities, elevated oxidations of lipids and proteins, increased intracellular calcium overload mediated endoplasmic reticular stress (ER stress) pathways, up regulated the pro-inflammatory cytokines and there by leading to the mitochondrial dependent caspase-3 activation and poly-ADP ribose polymerase (PARP) cleavage. Moreover investigation of these inherent molecular pathways exhibited that these alterations are associated with up regulation of MAPKs, inducible nitric oxide synthase (iNOS), heme oxygenase-1 and down regulation of survival proteins. However, PNP suppressed those apoptotic indices as evidenced from histopathological studies and DNA fragmentation analysis. Combining, results suggest that PNP could possibly provide a protection against indomethacin-induced hepatic pathophysiology.

Current Topics of Strategy of NSAID-Induced Small Intestinal Lesions

Small intestinal mucosal injuries have been recently recognized as common complications associated with non-steroidal anti-inflammatory drugs (NSAIDs) because video capsule endoscopy and balloon enteroscopy are now available for the detection of small intestinal lesions. Small intestinal injury occurs not in an acid-dependent mechanism but by various factors such as enteric bacteria, bile acids, prostaglandin (PG) deficiency and topical factors (abnormal intestinal mucosal permeability, mitochondrial dysfunction, reactive oxygen species, endoplasmic reticulum stress and so on), and there is no well-established prophylactic approach. Several experimental and clinical studies found the effectiveness of some of the mucoprotective drugs, PG analogs, but not that of acid suppressants. Considering the effect of proton pump inhibitors (PPIs) for upper gastrointestinal (GI) disease and in the small intestine, the following 2 kinds of strategies against NSAID-induced GI injuries may be recommended. In patients with a high risk of upper GI disease (peptic ulcer etc.), simultaneous administration of a PPI (for upper GI disease) and a mucoprotective drug (for small intestine) is needed to prevent NSAID-induced GI injury. In other cases, an effective mucoprotective drug is enough for the protection of the entire digestive tract, that is, starting from the esophagus to the small intestine. These strategies may fulfill both economical and curative effects.

ER Stress-Mediated Signaling: Action Potential and Ca(2+) as Key Players

The proper functioning of the endoplasmic reticulum (ER) is crucial for multiple cellular activities and survival. Disturbances in the normal ER functions lead to the accumulation and aggregation of unfolded proteins, which initiates an adaptive response, the unfolded protein response (UPR), in order to regain normal ER functions. Failure to activate the adaptive response initiates the process of programmed cell death or apoptosis. Apoptosis plays an important role in cell elimination, which is essential for embryogenesis, development, and tissue homeostasis. Impaired apoptosis can lead to the development of various pathological conditions, such as neurodegenerative and autoimmune diseases, cancer, or acquired immune deficiency syndrome (AIDS). Calcium (Ca(2+)) is one of the key regulators of cell survival and it can induce ER stress-mediated apoptosis in response to various conditions. Ca(2+) regulates cell death both at the early and late stages of apoptosis. Severe Ca(2+) dysregulation can promote cell death through apoptosis. Action potential, an electrical signal transmitted along the neurons and muscle fibers, is important for conveying information to, from, and within the brain. Upon the initiation of the action potential, increased levels of cytosolic Ca(2+) (depolarization) lead to the activation of the ER stress response involved in the initiation of apoptosis. In this review, we discuss the involvement of Ca(2+) and action potential in ER stress-mediated apoptosis.

Co-lyophilized Aspirin with Trehalose Causes Less Injury to Human Gastric Cells and Gastric Mucosa of Rats

BACKGROUND

Aspirin is one of the most popular NSAIDs worldwide because of its anti-inflammatory and anticoagulant effects, and however, gastrointestinal injury remains a major complication. We previously reported co-lyophilized aspirin/trehalose (Lyo A/T) decreased the aspirin-induced gastric lesions in dogs.

AIM

This study investigated the mechanism of gastroprotective effects of trehalose in vitro and in vivo.

METHODS

The apoptotic assays were performed in a human gastric carcinoma cell line, which was treated with aspirin, mixed aspirin/trehalose (Mix A/T) or Lyo A/T. Gastric ulcer severity was examined after oral administration of drugs in rats. In addition, the mucosal tissue apoptotic status in drug-treated rats was evaluated. Molecular dynamics simulations and laser Raman spectroscopy were performed in order to examine the molecular properties of Lyo A/T.

RESULTS

DNA fragmentation was detected in AGS cells that were treated with aspirin and Mix A/T, but not in the Lyo A/T-treated cells. There were fewer apoptotic cells in the Lyo A/T-treated cells than in the other cells. Gastric injury was reduced in rats that received oral Lyo A/T compared with the others, while PGE2 synthesis was equally decreased in all groups. TUNEL assay and immunohistochemistry of cleaved caspase-3 in the mucosal tissues also revealed that Lyo A/T treatment induced less apoptosis than the others. The Lyo A/T spectrum showed clear differences in several Raman bands compared with that of Mix A/T.

CONCLUSIONS

Our data showed that co-lyophilization of aspirin with trehalose reduced gastric injury, potentially through suppression of aspirin-induced mucosal cell apoptosis while retaining its anti-inflammatory effects.

The use of cyclooxygenase-2 inhibitors for improvement of efficacy of radiotherapy in cancers

Cyclooxygenase-2 (COX-2) is overexpressed in cancer cells and is associated with carcinogenesis and maintenance of progressive tumour growth as well as resistance of cancer cells to ionising radiation (IR). COX-2 inhibitors can attenuate tumour growth and expression of markers of cell proliferation as well as induce apoptosis in tumour cells. These agents can have a synergistic effect with IR in the killing of cancer cells. In this review, we discuss the rational basis and molecular mechanisms regarding the usefulness of COX-2 inhibitors in cancer therapy, and also their potential role in increasing the therapeutic index of chemoradiation by protecting normal cells and sensitising tumour cells to radiotherapy.

Role of endoplasmic reticulum stress in drug-induced toxicity

Drug‐induced toxicity is a key issue for public health because some side effects can be severe and life‐threatening. These adverse effects can also be a major concern for the pharmaceutical companies since significant toxicity can lead to the interruption of clinical trials, or the withdrawal of the incriminated drugs from the market. Recent studies suggested that endoplasmic reticulum (ER) stress could be an important event involved in drug liability, in addition to other key mechanisms such as mitochondrial dysfunction and oxidative stress. Indeed, drug‐induced ER stress could lead to several deleterious effects within cells and tissues including accumulation of lipids, cell death, cytolysis, and inflammation. After recalling important information regarding drug‐induced adverse reactions and ER stress in diverse pathophysiological situations, this review summarizes the main data pertaining to drug‐induced ER stress and its potential involvement in different adverse effects. Drugs presented in this review are for instance acetaminophen (APAP), arsenic trioxide and other anticancer drugs, diclofenac, and different antiretroviral compounds. We also included data on tunicamycin (an antibiotic not used in human medicine because of its toxicity) and thapsigargin (a toxic compound of the Mediterranean plant Thapsia garganica) since both molecules are commonly used as prototypical toxins to induce ER stress in cellular and animal models.

A high throughput Cre-lox activated viral membrane fusion assay identifies pharmacological inhibitors of HIV entry

Enveloped virus entry occurs when viral and cellular membranes fuse releasing particle contents into the target cell. Human immunodeficiency virus (HIV) entry occurs by cell-free virus or virus transferred between infected and uninfected cells through structures called virological synapses. We developed a high-throughput cell-based assay to identify small molecule inhibitors of cell-free or virological synapse-mediated entry. An HIV clone carrying Cre recombinase as a Gag-internal gene fusion releases active Cre into cells upon viral entry activating a recombinatorial gene switch changing dsRed to GFP-expression. A screen of a 1998 known-biological profile small molecule library identified pharmacological HIV entry inhibitors that block both cell-free and cell-to-cell infection. Many top hits were noted as HIV inhibitors in prior studies, but not previously recognized as entry antagonists. Modest therapeutic indices for simvastatin and nigericin were observed in confirmatory HIV infection assays. This robust assay is adaptable to study HIV and heterologous viral pseudotypes.

COX-2 inhibitor NS-398 suppresses doxorubicin-induced p53 accumulation through inhibition of ROS-mediated Jnk activation

Cyclooxygenase-2 (COX-2) is one of the isoforms of cyclooxygenase, a rate-limiting enzyme in the arachidonic acid cascade. COX-2 protein expression is highly induced by numerous factors and it has been reportedly overexpressed in various human malignancies. Although anti-tumorigenic effects of COX-2 inhibitors have been shown, several lines of evidence suggest that COX-2 inhibitors antagonize the cytotoxicity of chemotherapeutic agents. In this study, we investigated the effect of NS-398, a COX-2 inhibitor, on modulation of doxorubicin (DOX)-induced p53 accumulation. Non-selective and selective COX-2 inhibitors attenuated DOX-induced accumulation of wild type (WT) but not mutant p53. Nutlin-3α or MG132 abolished the suppressive effect of a COX-2 inhibitor on DOX-induced p53 increase. Moreover, the DOX-induced increase in p53 protein levels was reduced in COX-2 knockout (KO) mouse embryonic fibroblasts (MEFs) compared to those in WT or COX-1 KO MEFs. DOX-induced accumulation of p53 was attenuated by a specific inhibitor or knockdown of Jun-N-terminal kinase (Jnk). In addition, DOX-induced Jnk activation was decreased in COX-2 KO MEFs or by COX-2 inhibition, suggesting that Jnk stabilizes p53 by a mechanism that involves COX-2. Pre-treatment with a reactive oxygen species (ROS) scavenger, N-acetylcysteine, attenuated DOX-induced Jnk activation and subsequent p53 accumulation. Furthermore, the absence or inhibition of COX-2 resulted in suppression of DOX-induced increase in ROS levels. These results suggest that COX-2 activates Jnk through modulation of ROS levels, leading to accumulation of p53. Our study identifies a putative novel cross-talk between COX-2 and p53. © 2016 Wiley Periodicals, Inc.

Selective and non-selective non-steroidal anti-inflammatory drugs differentially regulate pulmonary vein and atrial arrhythmogenesis

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of atrial fibrillation (AF). This study investigated whether selective and non-selective NSAIDs differentially regulate the arrhythmogenesis of pulmonary veins and atria.

METHODS

Conventional microelectrodes were used to record action potentials (APs) in isolated rabbit PVs, sinoatrial node (SAN), left atrium (LA), and right atrium (RA) preparations before and after celecoxib or indomethacin administration. A whole-cell patch clamp was used to record the sodium-calcium exchanger (NCX) current, L-type calcium current (ICa-L), and late sodium current (INa-late) before and after celecoxib administration in isolated PV cardiomyocytes.

RESULTS

Celecoxib (0.3, 1, and 3 μM) reduced PV spontaneous beating rates, and induced delayed afterdepolarizations and burst firings in four of eight PV preparations (50%, p<0.05). Celecoxib also reduced SAN beating rates and decreased AP durations (APDs) in RA and LA, but did not change the resting membrane potential. Indomethacin (0.3, 1, 3, and 10 μM) changed neither the PV or SAN beating rates nor RA APDs, but it reduced LA APDs. Celecoxib (3 μM) significantly increased the NCX current and decreased the ICa-L, but did not change the INa-late. Ranolazine (10 μM) suppressed celecoxib (3 μM)-induced PV burst firings in 6 (86%, p<0.05) of 7 PVs. KB-R7943 (10 μM) suppressed celecoxib (3 μM)-induced PV burst firings in 5 (71%, p<0.05) of 7 PVs.

CONCLUSIONS

Selective and non-selective NSAIDs differentially modulate PV and atrial electrophysiological characteristics. Celecoxib increased PV triggered activity through enhancement of the NCX current, which contributed to its arrhythmogenesis.

Effects of Dantrolene Treatment on Ventricular Electrophysiology and Arrhythmogenesis in Rats With Chronic β-Adrenergic Receptor Activation

Dantrolene, which is primarily used to treat malignant hyperthermia, has recently been suggested for the prevention of arrhythmogenesis in various animal models. In this study, the effects of dantrolene treatment on electrophysiological properties and ventricular arrhythmias (VAs) in rats with chronic β-adrenergic receptor (β-AR) activation were investigated. Rats were randomized to treatment with saline (control group), isoproterenol (ISO; ISO group), or ISO + dantrolene (ID group) for 2 weeks. An electrophysiological study was performed to assess action potential duration restitution (APDR) and induce action potential duration (APD) alternans or VA in vitro. The protein levels of Cav1.2, sarcoplasmic reticulum Ca2+-ATPase (SERCA2a), and ryanodine receptor 2 (RyR2) were detected by Western blot. Compared with the control group, chronic administration of ISO significantly increased APD, the maximum slope (Smax) of APDR curve, and the spatial dispersions of Smax and APD (all P < .01), and all effects were attenuated by dantrolene treatment (all P < .05). Additionally, chronic ISO administration significantly reduced the protein levels of SERCA2 and RyR2, but increased the Cav1.2 protein expression (all P < .05). However, compared with the ISO group, dantrolene treatment preserved SERCA2a and RyR2 protein levels and decreased Cav1.2 protein levels in the ID group (all P < .05). The intracellular Ca2+ ([Ca2+]i) levels measured by incubating isolated cardiomyocytes with Fluo-3/alveolar macrophages were significantly increased in the ISO group compared with the control group ( P < .01). Dantrolene treatment markedly reduced the rise of [Ca2+]i levels caused by chronic administration of ISO ( P < .05). Dantrolene treatment also prevented the reductions in the APD alternans and VA thresholds induced by chronic ISO stimulation (all P < .05). These data suggest that dantrolene stabilizes ventricular electrophysiological characteristics and increases the expression of key sarcoplasmic reticulum calcium cycling proteins to reduce vulnerability to VA in rats with chronic β-AR activation.

The ER stress inducer DMC enhances TRAIL-induced apoptosis in glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumour in humans and is highly resistant to current treatment modalities. We have explored the combined treatment of the endoplasmic reticulum (ER) stress-inducing agent 2,5-dimethyl-celecoxib (DMC) and TNF-related apoptosis-inducing ligand (TRAIL WT) or the DR5-specific TRAIL D269H/E195R variant as a potential new strategy to eradicate GBM cells using TRAIL-resistant and -sensitive GBM cells. GBM cell lines were investigated for their sensitivity to TRAIL, DMC and combination of both agents. Cell viability was measured by MTS assay and apoptosis was assessed by Annexin V/PI and acridine orange staining. Caspase activation and protein expression levels were analysed with Western blotting. Death Receptor (DR) cell surface expression levels were quantified by flow cytometry. DR5 expression was increased in U87 cells by ectopic expression using a retroviral plasmid and survivin expression was silenced using specific siRNAs. We demonstrate that A172 expresses mainly DR5 on the cell surface and that these cells show increased sensitivity for the DR5-specific rhTRAIL D269H/E195R variant. In contrast, U87 cells show low DR cell surface levels and is insensitive via both DR4 and DR5. We determined that DMC treatment displays a dose-dependent reduction in cell viability against a number of GBM cells, associated with ER stress induction, as shown by the up-regulation of glucose-regulated protein 78 (GRP78) and CCAAT/-enhancer-binding protein homologous protein (CHOP) in A172 and U87 cells. The dramatic decrease in cell viability is not accompanied by a correspondent increase in Annexin V/PI or caspase activation typically seen in apoptotic or/and necrotic cells within 24h of treatment. Although DMC did not affect DR5 expression in the GBM cells, it increased TRAIL-induced caspase-8 activation in both TRAIL-sensitive and -resistant cells, indicating that DMC potentiates initiator caspase activation in these cells. In A172 cells, sub-toxic concentrations of DMC greatly potentiated TRAIL-induced apoptosis. Furthermore, DMC strongly reduced survivin expression in A172 and U87 cells and silencing of this anti-apoptotic protein partially sensitized cells to TRAIL-induced apoptosis. Our findings corroborate that DMC is a promising agent against GBM, and uncovers a potential synergistic cooperation with TRAIL in this highly malignant cancer.

Inhibition mechanism of the intracellular transporter Ca2+-pump from sarco-endoplasmic reticulum by the antitumor agent dimethyl-celecoxib

Dimethyl-celecoxib is a celecoxib analog that lacks the capacity as cyclo-oxygenase-2 inhibitor and therefore the life-threatening effects but retains the antineoplastic properties. The action mechanism at the molecular level is unclear. Our in vitro assays using a sarcoplasmic reticulum preparation from rabbit skeletal muscle demonstrate that dimethyl-celecoxib inhibits Ca²⁺-ATPase activity and ATP-dependent Ca²⁺ transport in a concentration-dependent manner. Celecoxib was a more potent inhibitor of Ca²⁺-ATPase activity than dimethyl-celecoxib, as deduced from the half-maximum effect but dimethyl-celecoxib exhibited higher inhibition potency when Ca²⁺ transport was evaluated. Since Ca²⁺ transport was more sensitive to inhibition than Ca²⁺-ATPase activity the drugs under study caused Ca²⁺/P_i uncoupling. Dimethyl-celecoxib provoked greater uncoupling and the effect was dependent on drug concentration but independent of Ca²⁺-pump functioning. Dimethyl-celecoxib prevented Ca²⁺ binding by stabilizing the inactive Ca²⁺-free conformation of the pump. The effect on the kinetics of phosphoenzyme accumulation and the dependence of the phosphoenzyme level on dimethyl-celecoxib concentration were independent of whether or not the Ca²⁺–pump was exposed to the drug in the presence of Ca²⁺ before phosphorylation. This provided evidence of non-preferential interaction with the Ca²⁺-free conformation. Likewise, the decreased phosphoenzyme level in the presence of dimethyl-celecoxib that was partially relieved by increasing Ca²⁺ was consistent with the mentioned effect on Ca²⁺ binding. The kinetics of phosphoenzyme decomposition under turnover conditions was not altered by dimethyl-celecoxib. The dual effect of the drug involves Ca²⁺-pump inhibition and membrane permeabilization activity. The reported data can explain the cytotoxic and anti-proliferative effects that have been attributed to the celecoxib analog. Ligand docking simulation predicts interaction of celecoxib and dimethyl-celecoxib with the intracellular Ca²⁺ transporter at the inhibition site of hydroquinones.

Precision cut intestinal slices are an appropriate ex vivo model to study NSAID-induced intestinal toxicity in rats

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used therapeutic agents, however, they are associated with a high prevalence of intestinal side effects. In this investigation, rat precision cut intestinal slices (PCIS) were evaluated as an ex vivo model to study NSAID-induced intestinal toxicity. Firstly, PCIS were incubated with 0-200 μM diclofenac (DCF), one of the most intensively studied NSAIDs, to investigate whether they could correctly reflect the toxic mechanisms. DCF induced intestinal toxicity in PCIS was shown by morphological damage and ATP depletion. DCF induced endoplasmic-reticulum (ER) stress, mitochondrial injury and oxidative stress were reflected by up-regulated HSP-70 (heat shock protein 70) and BiP (binding immunoglobulin protein) gene expression, caspase 9 activation, GSH (glutathione) depletion and HO-1 (heme oxygenase 1) gene up-regulation respectively. Furthermore, DCF intestinal metabolites, which gave rise to protein adduct but not toxicity, were detected in PCIS. Secondly, PCIS were incubated with various concentrations of five NSAIDs. Typical NSAID-induced morphological changes were observed in PCIS. The ex vivo toxicity ranking (diflunisal> diclofenac = indomethacin > naproxen ≫ aspirin) showed good correlation with published in vitro and in vivo data, with diflunisal being the only exception. In conclusion, PCIS correctly reflect the various mechanisms of DCF-induced intestinal toxicity, and can serve as an ex vivo model for the prediction of NSAID-induced intestinal toxicity.

Structure-activity relationship of celecoxib and rofecoxib for the membrane permeabilizing activity

Non-steroidal anti-inflammatory drugs (NSAIDs) achieve their anti-inflammatory effect by inhibiting cyclooxygenase activity. We previously suggested that in addition to cyclooxygenase-inhibition at the gastric mucosa, NSAID-induced gastric mucosal cell death is required for the formation of NSAID-induced gastric lesions in vivo. We showed that celecoxib exhibited the most potent membrane permeabilizing activity among the NSAIDs tested. In contrast, we have found that the NSAID rofecoxib has very weak membrane permeabilizing activity. To understand the membrane permeabilizing activity of coxibs in terms of their structure-activity relationship, we separated the structures of celecoxib and rofecoxib into three parts, synthesized hybrid compounds by substitution of each of the parts, and examined the membrane permeabilizing activities of these hybrids. The results suggest that the sulfonamidophenyl subgroup of celecoxib or the methanesulfonylphenyl subgroup of rofecoxib is important for their potent or weak membrane permeabilizing activity, respectively. These findings provide important information for design and synthesis of new coxibs with lower membrane permeabilizing activity.

NSAIDs inhibit tumorigenesis, but how?

Numerous epidemiologic studies have reported that the long-term use of nonsteroidal anti-inflammatory drugs (NSAID) is associated with a significant decrease in cancer incidence and delayed progression of malignant disease. The use of NSAIDs has also been linked with reduced risk from cancer-related mortality and distant metastasis. Certain prescription-strength NSAIDs, such as sulindac, have been shown to cause regression of precancerous lesions. Unfortunately, the extended use of NSAIDs for chemoprevention results in potentially fatal side effects related to their COX-inhibitory activity and suppression of prostaglandin synthesis. Although the basis for the tumor growth-inhibitory activity of NSAIDs likely involves multiple effects on tumor cells and their microenvironment, numerous investigators have concluded that the underlying mechanism is not completely explained by COX inhibition. It may therefore be possible to develop safer and more efficacious drugs by targeting such COX-independent mechanisms. NSAID derivatives or metabolites that lack COX-inhibitory activity, but retain or have improved anticancer activity, support this possibility. Experimental studies suggest that apoptosis induction and suppression of β-catenin-dependent transcription are important aspects of their antineoplastic activity. Studies show that the latter involves phosphodiesterase inhibition and the elevation of intracellular cyclic GMP levels. Here, we review the evidence for COX-independent mechanisms and discuss progress toward identifying alternative targets and developing NSAID derivatives that lack COX-inhibitory activity but have improved antineoplastic properties.

Dermal cell damage induced by topical application of non-steroidal anti-inflammatory drugs is suppressed by trehalose co-lyophilization in ex vivo analysis

Topical administration of non-steroidal anti-inflammatory drugs (NSAIDs) is generally considered safer than oral administration, although the former can occasionally induce cutaneous irritation. We hypothesized that the cutaneous irritation by topical NSAIDs might be suppressed by trehalose, which has protective effects on biological membranes. Using the three-dimensional cultured human skin model, Living Skin Equivalent-high, we found that cutaneous damage due to NSAIDs was reduced by concomitant use of trehalose and that this effect of trehalose was reinforced by co-lyophilization of NSAIDs with trehalose. The anti-inflammatory effect of co-lyophilized NSAIDs with trehalose was comparable to that seen with NSAIDs alone in a rat model. Our results suggest that co-lyophilization of NSAIDs with trehalose might be a novel procedure that can help prevent NSAIDs-induced skin irritation.

COX-Independent Mechanisms of Cancer Chemoprevention by Anti-Inflammatory Drugs

Epidemiological and clinical studies suggest that non-steroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase (COX)-2 selective inhibitors, reduce the risk of developing cancer. Experimental studies in human cancer cell lines and rodent models of carcinogenesis support these observations by providing strong evidence for the antineoplastic properties of NSAIDs. The involvement of COX-2 in tumorigenesis and its overexpression in various cancer tissues suggest that inhibition of COX-2 is responsible for the chemopreventive efficacy of these agents. However, the precise mechanisms by which NSAIDs exert their antiproliferative effects are still a matter of debate. Numerous other studies have shown that NSAIDs can act through COX-independent mechanisms. This review provides a detailed description of the major COX-independent molecular targets of NSAIDs and discusses how these targets may be involved in their anticancer effects. Toxicities resulting from COX inhibition and the suppression of prostaglandin synthesis preclude the long-term use of NSAIDs for cancer chemoprevention. Furthermore, chemopreventive efficacy is incomplete and treatment often leads to the development of resistance. Identification of alternative NSAID targets and elucidation of the biochemical processes by which they inhibit tumor growth could lead to the development of safer and more efficacious drugs for cancer chemoprevention.

Co-administration of water containing magnesium ion prevents loxoprofen-induced lesions in gastric mucosa of adjuvant-induced arthritis rat

Non-steroidal anti-inflammatory drugs (NSAIDs) comprise one of the most frequently used classes of medicines in the world; however, NSAIDs have significant side effects, such as gastroenteropathy, and rheumatoid arthritis patients taking NSAIDs are more susceptible to NSAID-induced gastric lesions as compared to patients with other diseases. In Asian countries, loxoprofen has been used clinically for many years as a standard NSAID. We demonstrate the preventive effect of the co-administration of water containing magnesium ion (magnesium water, 1-200 µg/kg) on the ulcerogenic response to loxoprofen in adjuvant-induced arthritis (AA) rats. Oral administration of loxoprofen (100 mg/kg) caused hemorrhagic lesions in the gastric mucosa of AA rats 14 d after adjuvant injection, and, following loxoprofen administration, the lesion score of AA rats was significantly higher than that of normal rats. The expression of inducible nitric oxide synthase (iNOS) mRNA and nitric oxide (NO) production in the gastric mucosa of AA rats were also increased by the administration of loxoprofen, and the increase in lesions and NO were prevented by the administration of aminoguanidine, an iNOS inhibitor. The co-administration of magnesium water decreased the ulcerogenic response to loxoprofen in AA rats. In addition, the co-administration of magnesium water attenuated the increase in iNOS mRNA expression and NO production in AA rats receiving loxoprofen. These results suggest that the oral co-administration of magnesium water to AA rats has a potent preventive effect on the ulcerogenic response to loxoprofen, probably by inhibiting the rise in iNOS and NO levels in the gastric mucosa.

Celecoxib enhances radiosensitivity of hypoxic glioblastoma cells through endoplasmic reticulum stress

BACKGROUND

Refractoriness of glioblastoma multiforme (GBM) largely depends on its radioresistance. We investigated the radiosensitizing effects of celecoxib on GBM cell lines under both normoxic and hypoxic conditions.

METHODS

Two human GBM cell lines, U87MG and U251MG, and a mouse GBM cell line, GL261, were treated with celecoxib or γ-irradiation either alone or in combination under normoxic and hypoxic conditions. Radiosensitizing effects were analyzed by clonogenic survival assays and cell growth assays and by assessing apoptosis and autophagy. Expression of apoptosis-, autophagy-, and endoplasmic reticulum (ER) stress-related genes was analyzed by immunoblotting.

RESULTS

Celecoxib significantly enhanced the radiosensitivity of GBM cells under both normoxic and hypoxic conditions. In addition, combined treatment with celecoxib and γ-irradiation induced marked autophagy, particularly in hypoxic cells. The mechanism underlying the radiosensitizing effect of celecoxib was determined to be ER stress loading on GBM cells.

CONCLUSION

Celecoxib enhances the radiosensitivity of GBM cells by a mechanism that is different from cyclooxygenase-2 inhibition. Our results indicate that celecoxib may be a promising radiosensitizing drug for clinical use in patients with GBM.

[Identification of a molecular mechanism for actions of existing medicines and its application for drug development]

As a new strategy for drug discovery and development, we propose here the establishment of drug re-profiling strategy. In this strategy, the actions of existing medicines, whose safety and pharmacokinetic effects in humans have been confirmed already, are examined comprehensively at the molecular level and the results are used for the development of new medicines. For example, identification of the mechanisms underlying the side effects of medicines enables us to develop safer drugs. The results can also be used for developing existing drugs for use as medicines in treatment of other diseases. Promoting this research strategy could provide breakthroughs in drug discovery and development by pharmaceutical companies.

Orally administered phosphatidic acids and lysophosphatidic acids ameliorate aspirin-induced stomach mucosal injury in mice

BACKGROUND

Recent investigations revealed that lysophosphatidic acid (LPA), a phospholipid with a growth factor-like activity, plays an important role in the integrity of the gastrointestinal tract epithelium.

AIM

This paper attempts to clarify the effect of orally administered phosphatidic acid (PA) and LPA on aspirin-induced gastric lesions in mice.

MATERIALS AND METHODS

Phospholipids, a free fatty acid, a diacylglycerol and a triglyceride at 1 mM (5.7 μmol/kg body weight) or 0.1 mM were orally administered to mice 0.5 h before oral administration of aspirin (1.7 mmol/kg). The total length of lesions formed on the stomach wall was measured as a lesion index. Formation of LPA from PA in the mouse stomach was examined by in vitro (in stomach lavage fluid), ex vivo (in an isolated stomach) and in vivo (in the stomach of a living mouse) examinations of phospholipase activity.

RESULTS

Palmitic acid, dioleoyl-glycerol, olive oil and lysophosphatidylcholine did not affect the aspirin-induced lesions. In contrast, phosphatidylcholine (1 mM), LPA (1 mM) and PA (0.1, 1 mM) significantly reduced the lesion index. Evidence for formation of LPA from PA in the stomach by gastric phospholipase A2 was obtained by in vitro, ex vivo and in vivo experiments. An LPA-specific receptor, LPA2, was found to be localized on the gastric surface-lining cells of mice.

CONCLUSION

Pretreatment with PA-rich diets may prevent nonsteroidal anti-inflammatory drug-induced stomach ulcers.

CREBH determines the severity of sulpyrine-induced fatal shock

Although the pyrazolone derivative sulpyrine is widely used as an antipyretic analgesic drug, side effects, including fatal shock, have been reported. However, the molecular mechanism underlying such a severe side effect is largely unclear. Here, we report that the transcription factor CREBH that is highly expressed in the liver plays an important role in fatal shock induced by sulpyrine in mice. CREBH-deficient mice were resistant to experimental fatal sulpyrine shock. We found that sulpyrine-induced expression of cytochrome P450 2B (CYP2B) family genes, which are involved in sulpyrine metabolism, in the liver was severely impaired in CREBH-deficient mice. Moreover, introduction of CYP2B in CREBH-deficient liver restored susceptibility to sulpyrine. Furthermore, ectopic expression of CREBH up-regulated CYP2B10 promoter activity, and in vivo knockdown of CREBH in wild-type mice conferred a significant resistance to fatal sulpyrine shock. These data demonstrate that CREBH is a positive regulator of CYP2B in response to sulpyrine administration, which possibly results in fatal shock.

Sulindac sulfide inhibits sarcoendoplasmic reticulum Ca2+ ATPase, induces endoplasmic reticulum stress response, and exerts toxicity in glioma cells: relevant similarities to and important differences from celecoxib

Malignant gliomas have low survival expectations regardless of current treatments. Nonsteroidal anti-inflammatory drugs (NSAIDs) prevent cell transformation and slow cancer cell growth by mechanisms independent of cyclooxygenase (COX) inhibition. Certain NSAIDs trigger the endoplasmic reticulum stress response (ERSR), as revealed by upregulation of molecular chaperones such as GRP78 and C/EBP homologous protein (CHOP). Although celecoxib (CELE) inhibits the sarcoendoplasmic reticulum Ca(2+) ATPase (SERCA), an effect known to induce ERSR, sulindac sulfide (SS) has not been reported to affect SERCA. Here, we investigated these two drugs for their effects on Ca(2+) homeostasis, ERSR, and glioma cell survival. Our findings indicate that SS is a reversible inhibitor of SERCA and that both SS and CELE bind SERCA at its cyclopiazonic acid binding site. Furthermore, CELE releases additional Ca(2+) from the mitochondria. In glioma cells, both NSAIDS upregulate GRP78 and activate ER-associated caspase-4 and caspase-3. Although only CELE upregulates the expression of CHOP, it appears that CHOP induction could be associated with mitochondrial poisoning. In addition, CHOP induction appears to be uncorrelated with the gliotoxicity of these NSAIDS in our experiments. Our data suggest that activation of ERSR is primarily responsible for the gliotoxic effect of these NSAIDS. Because SS has good brain bioavailability, has lower COX-2 inhibition, and has no mitochondrial effects, it represents a more appealing molecular candidate than CELE to achieve gliotoxicity via activation of ERSR.

Multiple NSAID-induced hits injure the small intestine: underlying mechanisms and novel strategies

Nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious gastrointestinal (GI) injury including jejunal/ileal mucosal ulceration, bleeding, and even perforation in susceptible patients. The underlying mechanisms are largely unknown, but they are distinct from those related to gastric injury. Based on recent insights from experimental models, including genetics and pharmacology in rodents typically exposed to diclofenac, indomethacin, or naproxen, we propose a multiple-hit pathogenesis of NSAID enteropathy. The multiple hits start with an initial pharmacokinetic determinant caused by vectorial hepatobiliary excretion and delivery of glucuronidated NSAID or oxidative metabolite conjugates to the distal small intestinal lumen, where bacterial β-glucuronidase produces critical aglycones. The released aglycones are then taken up by enterocytes and further metabolized by intestinal cytochrome P450s to potentially reactive intermediates. The "first hit" is caused by the NSAID and/or oxidative metabolites that induce severe endoplasmic reticulum stress or mitochondrial stress and lead to cell death. The "second hit" is created by the significant subsequent inflammatory response that would follow such a first-hit injury. Based on these putative mechanisms, strategies have been developed to protect the enterocytes from being exposed to the parent NSAID and/or oxidative metabolites. Among these, a novel strategy already demonstrated in a murine model is the selective disruption of bacteria-specific β-glucuronidases with a novel small molecule inhibitor that does not harm the bacteria and that alleviates NSAID-induced enteropathy. Such mechanism-based strategies require further investigation but provide potential avenues for the alleviation of the GI toxicity caused by multiple NSAID hits.

Yeast sensors for novel drugs: chloroquine and others revealed

In this study the mitochondrion is regarded as a target to reveal compounds that may be used to combat various diseases. Consequently, the sexual structures of yeasts (with high mitochondrial activity) were identified as sensors to screen for various anti-mitochondrial drugs that may be toxic to humans and that are directed, amongst others, against fungal diseases and cancer. Strikingly, these sensors indicated that chloroquine is a potent pro-mitochondrial drug which stimulated yeast sexual reproduction. In addition, these sensors also showed that some Non-Steroidal Anti-Inflammatory drugs (NSAIDs), anti-malarial drugs, antifungal and anticancer drugs are anti-mitochondrial. These yeast sensor bio-assays may fast track studies aimed at discovering new drugs as well as their mechanisms and should now be further evaluated for selectivity towards anti-/ pro-mitochondrials, fertility drugs and contraceptives, using in vitro, in vivo, in silico and omics research.

Pathogenesis of NSAID-induced gastric damage: importance of cyclooxygenase inhibition and gastric hypermotility

This article reviews the pathogenic mechanism of non-steroidal anti-inflammatory drug (NSAID)-induced gastric damage, focusing on the relation between cyclooxygenase (COX) inhibition and various functional events. NSAIDs, such as indomethacin, at a dose that inhibits prostaglandin (PG) production, enhance gastric motility, resulting in an increase in mucosal permeability, neutrophil infiltration and oxyradical production, and eventually producing gastric lesions. These lesions are prevented by pretreatment with PGE₂ and antisecretory drugs, and also via an atropine-sensitive mechanism, not related to antisecretory action. Although neither rofecoxib (a selective COX-2 inhibitor) nor SC-560 (a selective COX-1 inhibitor) alone damages the stomach, the combined administration of these drugs provokes gastric lesions. SC-560, but not rofecoxib, decreases prostaglandin E₂ (PGE₂) production and causes gastric hypermotility and an increase in mucosal permeability. COX-2 mRNA is expressed in the stomach after administration of indomethacin and SC-560 but not rofecoxib. The up-regulation of indomethacin-induced COX-2 expression is prevented by atropine at a dose that inhibits gastric hypermotility. In addition, selective COX-2 inhibitors have deleterious influences on the stomach when COX-2 is overexpressed under various conditions, including adrenalectomy, arthritis, and Helicobacter pylori-infection. In summary, gastric hypermotility plays a primary role in the pathogenesis of NSAID-induced gastric damage, and the response, causally related with PG deficiency due to COX-1 inhibition, occurs prior to other pathogenic events such as increased mucosal permeability; and the ulcerogenic properties of NSAIDs require the inhibition of both COX-1 and COX-2, the inhibition of COX-1 upregulates COX-2 expression in association with gastric hypermotility, and PGs produced by COX-2 counteract the deleterious effect of COX-1 inhibition.

Enhanced antitumor effect of lower-dose and longer-term CPT-11 treatment in combination with low-dose celecoxib against neuroblastoma xenografts

BACKGROUND

We have previously reported that the combination of low-dose (5.9 mg/kg/dose) irinotecan (CPT-11) and simultaneous low-dose (5 mg/kg/dose) celecoxib, a cyclooxygenase-2 inhibitor, administered for 20 consecutive days, had synergistic antitumor activity against human neuroblastoma xenografts in mice. Possible further antitumor efficacy of lower-dose and longer-term CPT-11 combined with simultaneous low-dose celecoxib was investigated for chemosensitive TNB9 and multi-drug resistant TS-N-2nu neuroblastoma xenografts.

METHODS

The time from initiation of drug treatment to tumor regrowth, tumor doubling time, and body weight change of mice were evaluated between treatments with lower-dose (3 mg/kg/dose) CPT-11 alone and the combination of the two drugs for 60 consecutive days. Induction of apoptosis and autophagy during treatments were analyzed by immunoblotting, real-time quantitative RT-PCR, TUNEL assay, and immunohistochemistry.

RESULTS

The combination of the two drugs administered for 60 consecutive days resulted in a significantly longer time to tumor regrowth (p < 0.011) and longer tumor doubling time (p < 0.013) in both xenografts than for the lower-dose CPT-11 therapy alone, without substantial side effects in mice. In particular, five of six TNB9 tumors treated with the combination of the two drugs showed no regrowth even 120 or 150 days after the initiation of therapy. The combined treatment suppressed the induction of autophagy leading to apoptosis in TNB9 tumors, and induced autophagy to enhance the antitumor effect in TS-N-2nu tumors.

CONCLUSION

Our findings demonstrate that lower-dose and longer-term CPT-11 treatment in combination with simultaneous low-dose celecoxib enhances antitumor activity and can successfully eradicate most of the neuroblastoma xenografts.

Lansoprazole inhibits mitochondrial superoxide production and cellular lipid peroxidation induced by indomethacin in RGM1 cells

Lansoprazole is effective in healing non-steroidal anti-inflammatory drugs induced ulcers, and antioxidant properties have been thought to play a key role in healing ulcers. We hypothesize that lansoprazole exerts a cytoprotective effect by inhibiting reactive oxygen species leakage from mitochondria and lipid peroxidation. We pretreated gastric epithelial RGM1 cells with lansoprazole and then treated them with indomethacin in vitro. We found that the lansoprazole pretreatment significantly reduced cellular injury, maintained mitochondrial transmembrane potential, and decreased lipid peroxidation. Furthermore, the signal intensity of the electron spin resonance spectrum of the indomethacin-treated mitochondria which were pretreated with lansoprazole showed considerable reduction compared to those without the lansoprazole pretreatment. These results suggest that lansoprazole reduced superoxide production in the mitochondria of indomethacin treated cells, and subsequently inhibited lipid peroxide and cellular injury in gastric epithelial cells.

Drug discovery and development focusing on existing medicines: drug re-profiling strategy

As a new strategy for drug discovery and development, I focus on drug re-profiling as a way to identify new treatments for diseases. In this strategy, the actions of existing medicines, whose safety and pharmacokinetic effects in humans have already been confirmed clinically and approved for use, are examined comprehensively at the molecular level and the results used for the development of new medicines. This strategy is based on the fact that we still do not understand the underlying mechanisms of action of many existing medicines, and as such the cellular responses that give rise to their main effects and side effects are yet to be elucidated. To this extent, identification of the mechanisms underlying the side effects of medicines offers a means for us to develop safer drugs. The results can also be used for developing existing drugs for use as medicines for the treatment of other diseases. Promoting this research strategy could provide breakthroughs in drug discovery and development.

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.

ERK/ribosomal S6 kinase (RSK) signaling positively regulates death receptor 5 expression through co-activation of CHOP and Elk1

Death receptor 5 (DR5) is a death domain-containing transmembrane receptor that triggers apoptosis upon binding to its ligand or when overexpressed. Its expression is induced by certain small molecule drugs, including celecoxib, through mechanisms that have not been fully elucidated. The current study has revealed a novel ERK/ribosomal S6 kinase (RSK)-dependent mechanism that regulates DR5 expression primarily using celecoxib as a DR5 inducer. Both C/EBP homologous protein (CHOP) and Elk1 are required for celecoxib-induced DR5 expression based on promoter deletion and mutation analysis and siRNA-mediated gene silencing results. Co-expression of both CHOP and Elk1 exhibited enhanced effects on increasing DR5 promoter activity and DR5 expression, indicating that CHOP and Elk1 co-operatively regulate DR5 expression. Because Elk1 is an ERK-regulated protein, we accordingly found that celecoxib increased the levels of phosphorylated ERK1/2, RSK2, and Elk1. Inhibition of either ERK signaling with a MEK inhibitor or ERK1/2 siRNA, or RSK2 signaling with an RSK2 inhibitor or RSK2 siRNA abrogated DR5 up-regulation by celecoxib as well as other agents. Moreover, these inhibitions suppressed celecoxib-induced CHOP up-regulation. Thus, ERK/RSK-dependent, CHOP and Elk1-mediated mechanisms are critical for DR5 induction. Additionally, celecoxib increased CHOP promoter activity in an ATF4-dependent manner, and siRNA-mediated blockade of ATF4 abrogated both CHOP induction and DR5 up-regulation, indicating that ATF4 is involved in celecoxib-induced CHOP and DR5 expression. Collectively, we conclude that small molecules such as celecoxib induce DR5 expression through activating ERK/RSK signaling and subsequent Elk1 activation and ATF4-dependent CHOP induction.