Induction of apoptotic DNA fragmentation by nonsteroidal anti-inflammatory drugs in cultured rat gastric mucosal cells

Ketorolac disturbs proteasome functions and induces mitochondrial abnormality-associated apoptosis

Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended to treat moderate-to-severe pain. Previous studies suggest that NSAIDs can suppress cellular proliferation and elevate apoptosis in different cancer cells. Ketorolac is an NSAID and can reduce the cancer cells' viability. However, molecular mechanisms by which Ketorolac can induce apoptosis and be helpful as an anti-tumor agent against carcinogenesis are unclear. Here, we observed treatment with Ketorolac disturbs proteasome functions, which induces aggregation of aberrant ubiquitinated proteins. Ketorolac exposure also induced the aggregation of expanded polyglutamine proteins, results cellular proteostasis disturbance. We found that the treatment of Ketorolac aggravates the accumulation of various cell cycle-linked proteins, which results in pro-apoptotic induction in cells. Ketorolac-mediated proteasome disturbance leads to mitochondrial abnormalities. Finally, we have observed that Ketorolac treatment depolarized mitochondrial membrane potential, released cytochrome c into cytoplasm, and induced apoptosis in cells, which could be due to proteasome functional depletion. Perhaps more in-depth research is required to understand the details of NSAID-based anti-proliferative molecular mechanisms that can elevate apoptosis in cancer cells and generate anti-tumor potential with the combination of putative cancer drugs.

Recent progress in adverse events of carboxylic acid non-steroidal anti-inflammatory drugs (CBA-NSAIDs) and their association with the metabolism: the consequences on mitochondrial dysfunction and oxidative stress, and prevention with natural plant extracts

INTRODUCTION

Carboxylic acid non-steroidal anti-inflammatory drugs (CBA-NSAIDs) are extensively used worldwide due to their antipyretic, analgesic, and anti-inflammatory effects. CBA-NSAIDs have reasonable margin of safety at therapeutic doses, and in the current climate, do not possess addiction potential like opioid drugs. Studies have revealed that various adverse events of CBA-NSAIDs are related mitochondrial dysfunction and oxidative stress.

AREAS COVERED

This review article summarizes adverse events induced by CBA-NSAIDs, mechanisms of mitochondrial damage, oxidative stress, and metabolic interactions. Meanwhile, this review discusses the treatment and prevention of CBA-NSAIDs damage by natural plant extracts based on antioxidant effects.

EXPERT OPINION

CBA-NSAIDs can induce reactive oxygen species (ROS) production, mediate DNA, protein and lipid damage, lead to imbalance of cell antioxidant status, change of mitochondrial membrane potential, activate oxidative stress signal pathway, thus leading to oxidative stress and cell damage. Adverse events caused by CBA-NSAIDs often exhibit dose and time dependence. In order to avoid adverse events caused by CBA-NSAIDs, it is necessary to provide detailed patient consultation and eliminate influencing factors. Moreover, constructive research studies on the organ-specific toxicity and mechanism of natural plant extracts in preventing and treating metabolic abnormalities of CBA-NSAIDs, will provide important value for warning and guidance for use of CBA-NSAIDs.

Xiaojianzhong decoction attenuates aspirin-induced gastric mucosal injury via the PI3K/AKT/mTOR/ULK1 and AMPK/ULK1 pathways

CONTEXT

Xiaojianzhong decoction (XJZD), classically prescribed in Chinese medicine, has protective and healing effects on gastric mucosal injury. However, the exact mechanism behind this effect remains unclear.

OBJECTIVE

To investigate the effect of XJZD on gastric mucosal injury and explore its underlying mechanisms.

MATERIALS AND METHODS

C57BL/6 mice were randomized into six groups (n = 10): the control group receiving sterile water, the model (aspirin 300 mg/kg), the XJZD high-dose (12 g/kg), XJZD medium-dose (6 g/kg), XJZD low-dose (3 g/kg) and omeprazole (20 mg/kg) groups, by gavage daily for 14 days. The area of gastric mucosal injury, mucosal injury index and degree of histopathological damage were analysed. Gastric mucosal epithelial cell apoptosis was detected. Epithelial cell autophagy was observed. The expression levels of tight junction proteins and proteins related to apoptosis, autophagy and the pentose phosphate pathway were analysed.

RESULTS

The results showed that after treatment with XJZD (12, 6 and 3 g/kg), the mucosal injury area was reduced (83.4%, 22.6% and 11.3%), the expression level of ZO-1 and occludin was up-regulated, the apoptosis rate of epithelial cells was reduced (40.8%, 25.4% and 8.7%), the expression of autophagy-related proteins LC3 and Beclin1 was decreased and the expression of p62 was increased, the PI3K/AKT/mTOR/ULK1(ser757) signalling pathway was activated, and the AMPK/ULK1(ser317) signalling pathway was inhibited. In addition, XJZD can antagonize the imbalance of redox homeostasis caused by aspirin and protect the gastric mucosa.

DISCUSSION AND CONCLUSIONS

XJZD protects against aspirin-induced gastric mucosal injury, implying it to be a potential therapeutic agent.

Diclofenac Diminished the Unfolded Protein Response (UPR) Induced by Tunicamycin in Human Endothelial Cells

Diclofenac belongs to the class of nonsteroidal anti-inflammatory drugs (NSAIDs), which are amongst the most frequently prescribed drugs to treat fever, pain and inflammation. Despite the presence of NSAIDs on the pharmaceutical market for several decades, epidemiological studies have shown new clinical applications of NSAIDs, and new mechanisms of their action were discovered. The unfolded protein response (UPR) activated under endoplasmic reticulum (ER) stress is involved in the pathophysiology of many diseases and may become a drug target, therefore, the study evaluated the effects of diclofenac on the tunicamycin-induced UPR pathways in endothelial cells. RT PCR analysis showed that diclofenac significantly inhibited activation of ER stress-responsive genes, i.e., CHOP/DITT3, GRP78/HSPA5 and DNAJB9. Additionally, the drug diminished the significant upregulation and release of the GRP78 protein, as evaluated using the ELISA assay, which was likely to be involved in the mechanism of the UPR activation resulting in apoptosis induction in endothelial cells. These results suggest the value of diclofenac as a factor capable of restoring the ER homeostasis in endothelial cells by diminishing the UPR.

Indomethacin can induce cell death in rat gastric parietal cells through alteration of some apoptosis- and autophagy-associated molecules

In clinical medicine, indomethacin (IND, a non-steroidal anti-inflammatory drug) is used variously in the treatment of severe osteoarthritis, rheumatoid arthritis, gouty arthritis or ankylosing spondylitis. A common complication found alongside the therapeutic characteristics is gastric mucosal damage. This complication is mediated through apoptosis and autophagy of the gastrointestinal mucosal epithelium. Apoptosis and autophagy are critical homeostatic pathways catalysed by caspases downstream of the gastrointestinal mucosal epithelial injury. Both act through molecular signalling pathways characterized by the initiation, mediation, execution and regulation of the cell regulatory cycle. In this study we hypothesized that dysregulated apoptosis and autophagy are associated with IND-induced gastric damage. We examined the spectra of in vivo experimental gastric ulcers in male Sprague-Dawley rats through gastric gavage of IND. Following an 18-hour fast, IND was administered to experimental rats. They were sacrificed at 3-, 6- and 12-hour intervals. Parietal cells (H⁺ , K⁺ -ATPase β-subunit assay) and apoptosis (TUNEL assay) were determined. The expression of apoptosis-signalling caspase (caspases 3, 8, 9 and 12), DNA damage (anti-phospho-histone H2A.X) and autophagy (MAP-LC3, LAMP-1 and cathepsin B)-related molecules in gastric mucosal cells was examined. The administration of IND was associated with gastric mucosal erosions and ulcerations mainly involving the gastric parietal cells (PCs) of the isthmic and upper neck regions and a time-dependent gradual increase in the number of apoptotic PCs with the induction of both apoptotic (upregulation of caspases 3 and 8) cell death and autophagic (MAP-LC3-II, LAMP-1 and cathepsin B) cell death. Autophagy induced by fasting and IND 3 hours initially prompted the degradation of caspase 8. After 6 and 12 hours, damping down of autophagic activity occurred, resulting in the upregulation of active caspase 8 and its nuclear translocation. In conclusion we report that IND can induce time-dependent apoptotic and autophagic cell death of PCs. Our study provides the first indication of the interactions between these two homeostatic pathways in this context.

Cyclooxygenase-1 (COX-1) and COX-1 Inhibitors in Cancer: A Review of Oncology and Medicinal Chemistry Literature

Prostaglandins and thromboxane are lipid signaling molecules deriving from arachidonic acid by the action of the cyclooxygenase isoenzymes COX-1 and COX-2. The role of cyclooxygenases (particularly COX-2) and prostaglandins (particularly PGE₂) in cancer-related inflammation has been extensively investigated. In contrast, COX-1 has received less attention, although its expression increases in several human cancers and a pathogenetic role emerges from experimental models. COX-1 and COX-2 isoforms seem to operate in a coordinate manner in cancer pathophysiology, especially in the tumorigenesis process. However, in some cases, exemplified by the serous ovarian carcinoma, COX-1 plays a pivotal role, suggesting that other histopathological and molecular subtypes of cancer disease could share this feature. Importantly, the analysis of functional implications of COX-1-signaling, as well as of pharmacological action of COX-1-selective inhibitors, should not be restricted to the COX pathway and to the effects of prostaglandins already known for their ability of affecting the tumor phenotype. A knowledge-based choice of the most appropriate tumor cell models, and a major effort in investigating the COX-1 issue in the more general context of arachidonic acid metabolic network by using the systems biology approaches, should be strongly encouraged.

Muscle Injury After Intramuscular Administration of Diclofenac: A Case Report Supported by Magnetic Resonance Imaging

Intramuscular injection of diclofenac is still frequently practiced, although there is ample evidence that the risk of local tissue intolerability is highly underestimated. The aim of this study was to evaluate local toxicity in a patient using magnetic resonance imaging. A patient who gave written informed consent received a medically indicated intramuscular administration of diclofenac 75 mg/2 mL. Simultaneously with magnetic resonance imaging of the depot, a clinical–chemical evaluation and quantification of diclofenac in plasma was performed. A manifold enhancement of the T2-weighted magnetic resonance signal was observed in a muscle area of approximately 60 mL volume, with maximum signal intensity 30 min after injection, the time of maximum diclofenac plasma exposure. Plasma creatine kinase activity was elevated approximately sixfold within 8 h and normalized within 1 week, whereas the magnetic resonance enhancement disappeared within 5 weeks. Interestingly, the patient did not complain about any clinical symptoms at the injection site. Asymptomatic tissue injury after intramuscular injection of diclofenac, caused by intramuscular dosing, can be reliably evaluated by magnetic resonance imaging and should be applied early during the development of parenteral dosage forms.

Clinical Trials Registration Number: BB130/16 (Ethics Committee of the University Medicine Greifswald).

Na+ /H+ exchanger NHE1 and NHE2 have opposite effects on migration velocity in rat gastric surface cells

Following superficial injury, neighbouring gastric epithelial cells close the wound by rapid cell migration, a process called epithelial restitution. Na⁺/H⁺ exchange (NHE) inhibitors interfere with restitution, but the role of the different NHE isoforms expressed in gastric pit cells has remained elusive. The role of the basolaterally expressed NHE1 (Slc9a1) and the presumably apically expressed NHE2 (Slc9a2) in epithelial restitution was investigated in the nontransformed rat gastric surface cell line RGM1. Migration velocity was assessed by loading the cells with the fluorescent dye DiR and following closure of an experimental wound over time. Since RGM1 cells expressed very low NHE2 mRNA and have low transport activity, NHE2 was introduced by lentiviral gene transfer. In medium with pH 7.4, RGM1 cells displayed slow wound healing even in the absence of growth factors and independently of NHE activity. Growth factors accelerated wound healing in a partly NHE1‐dependent fashion. Preincubation with acidic pH 7.1 stimulated restitution in a NHE1‐dependent fashion. When pH 7.1 was maintained during the restitution period, migratory speed was reduced to ∼10% of the speed at pH 7,4, and the residual restitution was further inhibited by NHE1 inhibition. Lentiviral NHE2 expression increased the steady‐state pH_i and reduced the restitution velocity after low pH preincubation, which was reversible by pharmacological NHE2 inhibition. The results demonstrate that in RGM1 cells, migratory velocity is increased by NHE1 activation, while NHE2 activity inhibit this process. A differential activation of NHE1 and NHE2 may therefore, play a role in the initiation and completion of the epithelial restitution process.

Gastroprotective potential of hydro-alcoholic extract of Pattanga (Caesalpinia sappan Linn.)

ETHNO-PHARMACOLOGICAL RELEVANCE

Pattanga is botanically equated as Caesalpinia sappan Linn. (Family: Caesalpiniaceae) and is used in Ayurveda system of medicine since ages. According to Ayurveda, useful part is Heartwood, which is bitter, astringent and acrid and is useful in vitiated conditions of vata and pitta, burning sensation, wounds, ulcers, leprosy, skin diseases, menorrhagia, leucorrhea, and diabetes. It is used as a major ingredient in Ayurvedic formulations and preparations like Patrangasava, Chandanadya Thalia, and Karpuradyarka.

AIM OF THE STUDY

The present study is planned to evaluate the gastroprotective activity of the selected Ayurvedic drug using three different in vivo gastric ulcer models, so as to provide scientific evidence for the Ayurvedic claims.

MATERIALS AND METHODS

For this study, Wistar albino rats fasted overnight were selected. The hydroalcoholic extract of Caesalpinia sappan heartwood at the dose level 250 and 500mg/kg body weight was selected and administered orally before necrotizing agents. Antioxidant and antiulcer parameters were evaluated and the stomach samples were subjected for histopathological studies. In addition, PGE2 estimation and protein expressions of COX-1, COX-2 and iNOS were analyzed by Western blot. The plant extract was subjected to LCMS/MS analysis. In addition, Cytoprotective effect in isolated gastric mucosal cells, TUNEL Assay, Acid neutralizing capacity assay, H⁺/K⁺ ATPase inhibitory assay were performed.

RESULTS

The ulcer protection was found to be 92%, 86% and 64% against ethanol, NSAID and pylorus ligation induced ulcer respectively. The hydro-alcoholic extract of C. sappan heartwood exhibited cytoprotective effect with 76.82% reduction against indomethacin-induced cytotoxicity at the concentration of 25µg/ml. C. sappan showed 63.91% inhibition in H⁺/K⁺ ATPase inhibitory assay at the concentration 500µg/ml.

CONCLUSIONS

Our results depict that Caesalpinia sappan heartwood possesses gastroprotective activity, possibly mediated through cytoprotection and antioxidant mechanisms. The data obtained in the present study provides scientific support for the traditional use of Caesalpinia sappan in the management of peptic ulcer.

Repurposing Drugs in Oncology (ReDO)-diclofenac as an anti-cancer agent

Diclofenac (DCF) is a well-known and widely used non-steroidal anti-inflammatory drug (NSAID), with a range of actions which are of interest in an oncological context. While there has long been an interest in the use of NSAIDs in chemoprevention, there is now emerging evidence that such drugs may have activity in a treatment setting. DCF, which is a potent inhibitor of COX-2 and prostaglandin E2 synthesis, displays a range of effects on the immune system, the angiogenic cascade, chemo- and radio-sensitivity and tumour metabolism. Both pre-clinical and clinical evidence of these effects, in multiple cancer types, is assessed and summarised and relevant mechanisms of action outlined. Based on this evidence the case is made for further clinical investigation of the anticancer effects of DCF, particularly in combination with other agents - with a range of possible multi-drug and multi-modality combinations outlined in the supplementary materials accompanying the main paper.

Oxidative stress involvement and gene expression in indomethacin-induced gastropathy

It has been proposed that neutrophil- and oxygen radical-dependent microvascular injuries are important prime events that lead to gastric mucosal injury induced by indomethacin. Reactive oxygen species (ROS) produced by activated neutrophils after indomethacin treatment cause gastric mucosal injury via ROS-mediated oxidation of important biomolecules such as lipid, protein, and DNA. In addition, it has been revealed that indomethacin-induced gastric mucosal injury occurs via gastric epithelial cell apoptosis. However, there is little known about the mechanism of indomethacin-triggered cellular response and apoptotic signaling in gastric mucosal cells. In the present study, we summarize the evidence that supports the involvement of oxidative stress and apoptosis in indomethacin-induced gastropathy, and review the gene expression profiles of gastric epithelial cells after indomethacin treatment determined by DNA microarray analysis.

New NSAID targets and derivatives for colorectal cancer chemoprevention

Clinical and preclinical studies provide strong evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) can prevent numerous types of cancers, especially colorectal cancer. Unfortunately, the depletion of physiologically important prostaglandins due to cyclooxygenase (COX) inhibition results in potentially fatal toxicities that preclude the long-term use of NSAIDs for cancer chemoprevention. While studies have shown an involvement of COX-2 in colorectal tumorigenesis, other studies suggest that a COX-independent target may be at least partially responsible for the antineoplastic activity of NSAIDs. For example, certain NSAID derivatives have been identified that do not inhibit COX-2 but have demonstrated efficacy to suppress carcinogenesis with potential for reduced toxicity. A number of alternative targets have also been reported to account for the tumor cell growth inhibitory activity of NSAIDs, including the inhibition of cyclic guanosine monophosphate phosphodiesterases (cGMP PDEs), generation of reactive oxygen species (ROS), the suppression of the apoptosis inhibitor protein, survivin, and others. Here, we review several promising mechanisms that are being targeted to develop safer and more efficacious NSAID derivatives for colon cancer chemoprevention.

Novel Therapeutics: NSAIDs, Derivatives, and Phosphodiesterases

The chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) for colorectal cancer has been well documented. However, long-term use of NSAIDs is precluded owing to potentially fatal toxicities associated with their mechanism of action involving cyclooxygenase (COX) inhibition. But studies have shown that their anticancer activity may be due, in part, to an off-target effect. Cyclic guanosine monophosphate (cGMP) phosphodiesterases (PDEs), which are responsible for negative regulation of cGMP signaling, are an attractive COX-independent target. cGMP signaling is aberrantly suppressed in cancer cells and its activation appears to be sufficient to inhibit tumor cell growth. Chemically modifying sulindac has produced a series of new derivatives that lack COX-inhibitory activity but have improved cGMP PDE inhibitory activity. This approach is proving to be a promising strategy for the discovery of improved agents for the prevention and/or treatment of colorectal cancer.

A novel sulindac derivative that potently suppresses colon tumor cell growth by inhibiting cGMP phosphodiesterase and β-catenin transcriptional activity

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely reported to inhibit tumor growth by a COX-independent mechanism, although alternative targets have not been well defined or used to develop improved drugs for cancer chemoprevention. Here, we characterize a novel sulindac derivative referred to as sulindac benzylamine (SBA) that does not inhibit COX-1 or COX-2, yet potently inhibits the growth and induces the apoptosis of human colon tumor cells. The basis for this activity appears to involve cyclic guanosine 3',5',-monophosphate phosphodiesterase (cGMP PDE) inhibition as evident by its ability to inhibit cGMP hydrolysis in colon tumor cell lysates and purified cGMP-specific PDE5, increase intracellular cGMP levels, and activate cGMP-dependent protein kinase G at concentrations that suppress tumor cell growth. PDE5 was found to be essential for colon tumor cell growth as determined by siRNA knockdown studies, elevated in colon tumor cells as compared with normal colonocytes, and associated with the tumor selectivity of SBA. SBA activation of PKG may suppress the oncogenic activity of β-catenin as evident by its ability to reduce β-catenin nuclear levels, Tcf (T-cell factor) transcriptional activity, and survivin levels. These events preceded apoptosis induction and appear to result from a rapid elevation of intracellular cGMP levels following cGMP PDE inhibition. We conclude that PDE5 and possibly other cGMP degrading isozymes can be targeted to develop safer and more efficacious NSAID derivatives for colorectal cancer chemoprevention.

Discovery of a novel neuroprotective compound, AS1219164, by high-throughput chemical screening of a newly identified apoptotic gene marker

We have reported that tacrolimus (FK506), an immunosuppressive drug, and diclofenac, a non-steroidal anti-inflammatory drug, possess different modes of neuroprotective action. FK506 suppresses only thapsigargin-induced apoptosis in neuroblastoma SH-SY5Y cells while diclofenac reverses tunicamycin-induced as well as thapsigargin-induced apoptosis. The aim of this study is to discover novel compounds that exert neuroprotective properties by using the transcriptional response of a newly identified gene, which was regulated by both FK506 and diclofenac, as a surrogate screening marker in high-throughput chemical screening and characterize the compounds in comparison with FK506 and diclofenac. Using a microarray with 4504 human cDNAs and quantitative RT-PCR, two genes as apoptotic markers, transmembrane protein 100 (TMEM100) and limb-bud and heart (LBH), were identified because the thapsigargin-induced elevations in their mRNA levels were reversed by both FK506 and diclofenac. A luciferase reporter assay with a TMEM100 promoter region was applied to high-throughput chemical screening. AS1219164, {3-[(E)-2-{5-[(E)-2-pyridin-4-ylvinyl]pyridin-3-yl} vinyl]aniline}, suppressed thapsigargin-induced transactivation of the TMEM100 gene and reversed thapsigargin-induced increases in TMEM100 and LBH mRNA levels in SH-SY5Y cells, similar to the effects of FK506 and diclofenac. Furthermore, AS1219164 protected against SH-SY5Y cell death induced by four apoptotic agents including thapsigargin, similar to diclofenac, but was more potent than diclofenac, while FK506 only showed protective effects against thapsigargin-induced cell death. In conclusion, a novel neuroprotecitve compound, AS1219164, was discovered by high-throughput chemical screening using a reporter assay with the TMEM100 gene promoter regulated by both FK506 and diclofenac. Reporter assay using the promoter region of a gene under pharmacological and physiological transcriptional regulation would be well suit for use in high-throughput chemical screening.

Transcriptome Analysis for Cytoprotective Actions of Rebamipide against Indomethacin-Induced Gastric Mucosal Injury in Rats

We have reported that rebamipide, a gastroprotective drug, suppresses indomethacin-induced gastric mucosal injury in humans and rats. However, the mechanisms of the cytoprotective actions of rebamipide have not been fully addressed. In the present study, we determined mRNA expression profile of the gastric mucosa treated with indomethacin in rats, and investigated the cytoprotective effects of rebamipide against indomethacin-induced injury with a high-density oligonucleotide array (Rat Toxicology U34 GeneChip array). Gastric epithelial cells were obtained by laser-assisted microdissection. Data analysis was performed with a GeneChip Operating Software, GeneSpring software 7.0, and Ingenuity Pathway Analysis. Among 1,031 probes, the expression of 160 probes (15.5%) showed at least 2.0-fold up-regulation (158 probes) and down-regulation (2 probes) 2 h after indomethacin administration in comparison with the vehicle-treated rats. The pathway analysis of the up-regulated 123 probes identified the network with a highly significant score, which consisted of known clusters of cell death, cancer, and endocrine system disorders. We succeeded in listing 10 genes that were up-regulated by the treatment with indomethacin and that were down-regulated by rebamipide, including growth arrest and DNA damage-induced 45α. In conclusion, we demonstrated that cell death, especially apoptosis, pathway is involved in the pathogenesis of indomethacin-induced gastric mucosal injury, and that inhibition of apoptosis-related genes is possibly important for the cytoprotective effect of rebamipide against this injury.

Ellagic acid prevents rat colon carcinogenesis induced by 1, 2 dimethyl hydrazine through inhibition of AKT-phosphoinositide-3 kinase pathway

Colon cancer is the third most malignant neoplasm in the world and chemoprevention through dietary intervention is an emerging option to reduce its mortality. Ellagic acid (EA) a major component of berries possesses attractive biological deeds. This study is aimed to investigate the effect of ellagic acid in fostering apoptosis in 1,2-dimethyl hydrazine (DMH) mediated experimental colon carcinogenesis model. Wistar male rats were segregated into four groups: group I-control rats, group II-rats received ellagic acid (60 mg/kg body weight p.o. every day), rats in group III-induced with DMH (20 mg/kg body weight, s.c.) for 15 weeks, DMH-induced group IV rats were initiated with ellagic acid treatment. The present study is designed to explore the significance of phosphoinositide-3-kinase (PI3K)/Akt molecular pathway as well as ellagic acid's chemopreventive effect in colon cancer. DMH-induced rats exhibited elevated expressions of PI3K and Akt as confirmed by immunofluorescence, immunoblot and confocal microscopic analysis. Mechanistically, ellagic acid was found to prevent PI3K/Akt activation that in turn, results in modulation of its downstream Bcl-2 family proteins. Bax expression and caspase-3 activation was noted after ellagic acid supplementation leading to elevation of cytochrome c (cyt c) levels and finally cell death. These observations were supported by the DNA fragmentation results, which showed the occurrence of apoptosis. This study reveals the involvement of PI3K-Akt signaling through which ellagic acid induces apoptosis and subsequently suppresses colon cancer during DMH-induced rat colon carcinogenesis. In conclusion, our findings demonstrate that ellagic acid begets apoptosis in DMH-induced colon carcinoma.

Gallic acid prevents nonsteroidal anti-inflammatory drug-induced gastropathy in rat by blocking oxidative stress and apoptosis

Nonsteroidal anti-inflammatory drug (NSAID)-induced oxidative stress plays a critical role in gastric mucosal cell apoptosis and gastropathy. NSAIDs induce the generation of hydroxyl radical ((*)OH) through the release of free iron, which plays an important role in developing gastropathy. Thus, molecules having both iron-chelating and antiapoptotic properties will be beneficial in preventing NSAID-induced gastropathy. Gallic acid (GA), a polyphenolic natural product, has the capacity to chelate free iron. Here, we report that GA significantly prevents, as well as heals, NSAID-induced gastropathy. In vivo, GA blocks NSAID-mediated mitochondrial oxidative stress by preventing mitochondrial protein carbonyl formation, lipid peroxidation, and thiol depletion. In vitro, GA scavenges free radicals and blocks (*)OH-mediated oxidative damage. GA also attenuates gastric mucosal cell apoptosis in vivo as well as in vitro in cultured gastric mucosal cells as evident from the TUNEL assay. GA prevents NSAID-induced activation of caspase-9, a marker for the mitochondrial pathway of apoptosis, and restores NSAID-mediated collapse of the mitochondrial transmembrane potential and dehydrogenase activity. Thus, the inhibition of mitochondrial oxidative stress by GA is associated with the inhibition of NSAID-induced mitochondrial dysfunction and activation of apoptosis in gastric mucosal cells, which are responsible for gastric injury or gastropathy.

NSAIDs: Old Drugs Reveal New Anticancer Targets

There is compelling evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 selective inhibitors have antineoplastic activity, but toxicity from cyclooxygenase (COX) inhibition and the suppression of physiologically important prostaglandins limits their use for cancer chemoprevention. Previous studies as reviewed here suggest that the mechanism for their anticancer properties does not require COX inhibition, but instead involves an off-target effect. In support of this possibility, recent molecular modeling studies have shown that the NSAID sulindac can be chemically modified to selectively design out its COX-1 and COX-2 inhibitory activity. Unexpectedly, certain derivatives that were synthesized based on in silico modeling displayed increased potency to inhibit tumor cell growth. Other experiments have shown that sulindac can inhibit phosphodiesterase to increase intracellular cyclic GMP levels and that this activity is closely associated with its ability to selectively induce apoptosis of tumor cells. Together, these studies suggest that COX-independent mechanisms can be targeted to develop safer and more efficacious drugs for cancer chemoprevention.

Melatonin reduces indomethacin-induced gastric mucosal cell apoptosis by preventing mitochondrial oxidative stress and the activation of mitochondrial pathway of apoptosis

Augmentation of gastric mucosal cell apoptosis due to development of oxidative stress is one of the main pathogenic events in the development of nonsteroidal anti-inflammatory drug (NSAID)-induced gastropathy. Identification of a nontoxic, anti-apoptotic molecule is warranted for therapy against NSAID-induced gastropathy. The objective of the present study was to define the mechanism of the anti-apoptotic effect of melatonin, a nontoxic molecule which scavenges reactive oxygen species. Using an array of experimental approaches, we have shown that melatonin prevents the development of mitochondrial oxidative stress and activation of mitochondrial pathway of apoptosis induced by indomethacin (a NSAID) in the gastric mucosa. Melatonin inhibits the important steps of indomethacin-induced activation of mitochondrial pathway of apoptosis such as upregulation of the expression of Bax and Bak, and the downregulation of Bcl-2 and BclxL. Melatonin also prevents indomethacin-induced mitochondrial translocation of Bax and prevents the collapse of mitochondrial membrane potential. Moreover, melatonin reduces indomethacin-mediated activation of caspase-9 and caspase-3 by blocking the release of cytochrome c and finally rescues gastric mucosal cells from indomethacin-induced apoptosis as measured by the TUNEL assay. Histologic studies of gastric mucosa further document that melatonin almost completely protects against gastric damage induced by indomethacin. Thus, melatonin has significant anti-apoptotic effects to protect gastric mucosa from NSAID-induced apoptosis and gastropathy, which makes its use as potential therapy against gastric damage during NSAID treatment.

Morphological alteration in mitochondria following diclofenac and ibuprofen administration

This study was conducted to identify and to compare the mitochondrial morphological alterations in livers of rats treated with various doses of diclofenac and ibuprofen. Hundred and forty-four male Sprague Dawley rats were dosed with 3, 5 and 10 mg kg(-1) diclofenac and ibuprofen in saline via intraperitoneal injection for 15 days. The control group was administered with saline in a similar manner. Four rats were euthanised every 3 days until day 15. While 200 mg kg(-1) diclofenac and ibuprofen-treated rats (n = 4) were euthanized 10 h posttreatment. The livers were removed, cleaned and a section across the right lobe was taken and fixed in 4% (v/v) glutaraldehyde for electron microscopy analysis and the remaining samples were kept at -80 degrees C for Western blot analysis. Five milligram per kilogram and 10 mg kg(-1) diclofenac-administered rats for 15 days revealed the presence of enlarged mitochondria, irregular and ruptured mitochondrial membranes. While rats administered with 10 mg kg(-1) ibuprofen also showed the presence of mitochondria with irregular membrane structure and ruptured membranes. Western blotting analysis of mitochondrial fractions revealed the expression of cytochrome c in all samples and complete absence of cytochrome c expression in the cytosolic fraction of all samples after day 15. Analysis in 200 mg kg(-1) diclofenac and ibuprofen-treated groups, revealed expression of cytochrome c in both mitochondrial and cytosolic fractions. This observation indicates that both diclofenac and ibuprofen may alter the morphology of mitochondria, leading to cytochrome c release into the cytosol. Further studies needs to be conducted to investigate on the activity of the mitochondria following both treatments.

Aspirin-induced apoptosis in human gastric cancer epithelial cells: relationship with protein kinase C signaling

This study examined the relationship of protein kinase C (PKC) signaling with apoptosis induced by aspirin (ASA) in gastric surface cancer cells (AGS cell line). We found increased expression of two PKC isoforms (alpha and betaII) that translocated from the cytosol into the cell membrane fraction after ASA (40 mM) stimulation. PKC betaI expression markedly decreased in response to ASA treatment. This process was independent of caspase activation because no caspase inhibitors used (i.e., inhibitors to caspase 3, 6, 7, 8, and total caspase activity) significantly changed PKC processing, although inhibition of caspase cascade activity markedly attenuated the apoptosis induced by ASA as measured by DNA-histone complex formation. Upstream PKC signaling induced by ASA seems to play an important role in the regulation of apoptosis because PKC inhibitors significantly reduced the magnitude of DNA-histone complex formation. We conclude that ASA-induced apoptosis in gastric cancer cells is mediated, at least in part, through a PKC mechanism involving the (alpha) and (beta) isoforms and that PKC signaling operates upstream of the caspase cascade, which when activated elicits its downstream effects on DNA degradation.

Effects of hypothalamic paraventricular nuclei on apoptosis and proliferation of gastric mucosal cells induced by ischemia/reperfusion in rats

AIM: To investigate the effects of electrical stimulation of hypothalamic paraventricular nuclei (PVN) on gastric mucosal cellular apoptosis and proliferation induced by gastric ischemia/reperfusion (I/R) injury.

METHODS: For different experimental purposes, stimulating electrode plantation or electrolytic destruction of the PVN was applied, then the animals’ GI/R injury model was established by clamping the celiac artery for 30 min and allowing reperfusing the artery for 30 min, 1 h, 3 h or 6 h respectively. Then histological, immunohistochemistry methods were used to assess the gastric mucosal damage index, the gastric mucosal cellular apoptosis and proliferation at different times.

RESULTS: The electrical stimulation of PVN significantly attenuated the GI/R injury at 30 min, 1 h and 3 h after reperfusion. The electrical stimulation of PVN decreased gastric mucosal apoptosis and increased gastric mucosal proliferation. The electrolytic destruction of the PVN could eliminate the protective effects of electrical stimulation of PVN on GI/R injury. These results indicated that the PVN participated in the regulation of GI/R injury as a specific area in the brain, exerting protective effects against the GI/R injury, and the protection was associated with the inhibition of cellular apoptosis and the promotion of gastric mucosal proliferation.

CONCLUSION: Stimulating PVN significantly inhibits the gastric mucosal cellular apoptosis and promots gastric mucosal cellular proliferation. This may explain the protective mechanisms of electrical stimulation of PVN against GI/R injury.

Diclofenac, a non-steroidal anti-inflammatory drug, suppresses apoptosis induced by endoplasmic reticulum stresses by inhibiting caspase signaling

Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used in the treatment of inflammation and pain. In many reports, NSAIDs have induced apoptosis in a variety of cell lines such as colon cancer cells. On the other hand, more recently a few reports have found that NSAIDs protect against apoptosis. Here we investigate endoplasmic reticulum (ER)-stress-induced apoptosis of neuronal cells. The aim of this study is to examine the involvement of NSAIDs, in particular diclofenac, on ER-stress-induced apoptosis of human neuroblastoma SH-SY5Y cells. Diclofenac significantly suppressed SH-SY5Y cell death induced by two types of ER-stress-inducing agents: thapsigargin, an inhibitor of Ca2+-ATPase on the endoplasmic reticulum membrane, and tunicamycin, a glycosylation blocker. Other NSAIDs, such as indomethacin, ibuprofen, aspirin, and ketoprofen, also suppressed ER-stress-induced SH-SY5Y cell death. The dose-dependent anti-apoptotic effect of diclofenac did not correlate with the reduction of prostaglandin release. Administration of prostaglandin E2, which was a primary product of arachidonic metabolism, showed no effects against anti-apoptotic effects produced by diclofenac. Thapsigargin and tunicamycin each significantly activated caspase-3, -9, and -2 in the intrinsic apoptotic pathway in SH-SY5Y cells. Diclofenac suppressed the activation of caspases induced by both ER stresses. Thapsigargin and tunicamycin decreased the mitochondrial membrane potential in SH-SY5Y cells. Diclofenac suppressed the mitochondrial depolarization induced by both ER stresses. Diclofenac inhibited ER-stress-induced apoptosis of SH-SY5Y cells by suppressing the activation of caspases in the intrinsic apoptotic pathway. This is the first report to find that diclofenac has protective effects against ER-stress-induced apoptosis.

Rebamipide, a gastro-protective drug, inhibits indomethacin-induced apoptosis in cultured rat gastric mucosal cells: association with the inhibition of growth arrest and DNA damage-induced 45 alpha expression

Rebamipide, a gastromucosal protective drug, suppresses indomethacin-induced gastropathy in humans and rodents. Effects of rebamipide on gene expression in indomethacin-treated gastric mucosal cells (RGM1) were investigated using high-density oligonucleotide arrays. Indomethacin induced apoptosis in RGM1 cells in a dose-dependent manner. Rebamipide pretreatment significantly reduced indomethacin-induced apoptosis. We used gene expression profiling on high-density oligonucleotide probe arrays to characterize the transcriptional response of RGM1 cells to indomethacin treatment for 6 hr. Of the 8,799 probes examined, 717 (8.1%) were induced (400 probes) or repressed (317 probes) at least 1.5-fold. Among the 158 genes that were induced by indomethacin at least 2.0-fold, four genes that were down-regulated by rebamipide at least 2.0-fold are listed: growth arrest and DNA-damage-inducible 45 alpha (GADD 45 alpha), golgi SNAP receptor complex member 1, iodothyronine deiodinases, and transcription factor 8. Real time-PCR confirmed GADD 45 alpha expression and its inhibition by rebamipide. Inhibition of apoptosis-related genes is possibly important for the cytoprotective effect of rebamipide against indomethacin-induced gastric mucosal cell injury.

Survivin: a novel target for indomethacin-induced gastric injury

BACKGROUND & AIMS

Nonsteroidal anti-inflammatory drugs (NSAIDs) cause gastrointestinal erosions and ulcers. Apoptosis is one of the mechanisms. The role of survivin, an antiapoptosis protein, in NSAID-induced gastric injury is unknown. We examined the role of survivin in NSAID-induced gastric mucosal and gastric cell injury.

METHODS

We examined: (1) the effects of indomethacin (nonselective NSAID), celecoxib and NS-398 (cyclooxygenase [COX]-2-selective NSAIDs), SC-560 (a COX-1-selective NSAID), and SC-560 plus celecoxib on survivin expression and extent of injury in rat gastric mucosa; (2) the effects of indomethacin, NS-398, SC-560, and SC-560 plus NS-398 on survivin expression and injury in gastric epithelial (RGM-1) cells; and (3) the effects of survivin suppression with small interfering RNA (siRNA) on RGM-1 cell integrity at baseline and following indomethacin injury.

RESULTS

Indomethacin treatment dose-dependently reduced survivin protein levels and caused severe injury of gastric mucosa and RGM-1 cells. Suppression of survivin expression with siRNA in RGM-1 cells caused cell damage and increased susceptibility to injury by indomethacin. Celecoxib treatment caused exfoliation of the mucosal surface epithelium, but neither caused deep erosions or altered survivin expression. Neither NS-398 nor SC-560 treatment altered survivin levels or produced injury in vivo or in vitro. COX-1 and COX-2 inhibitor combination caused injury in vivo and in vitro but did not decrease survivin expression.

CONCLUSIONS

(1) Indomethacin, but not selective COX-1 or COX-2 inhibitors alone or in combination, reduces survivin expression in gastric mucosal cells and (2) significant reduction of survivin precedes greater severity of gastric injury.

Prostaglandin D(2) and J(2) induce apoptosis in human leukemia cells via activation of the caspase 3 cascade and production of reactive oxygen species

The presence of prostaglandins (PGs) has been demonstrated in the processes of carcinogenesis and inflammation. In the present study, we found that 12-o-tetradecanoylphorbol 13-acetate (TPA) induced cyclooxygenase 2 (COX-2), but not COX-1, protein expression in HL-60 cells, and the addition of arachidonic acid (AA) in the presence or absence of TPA significantly reduced the viability of HL-60 cells, an effect that was blocked by adding the COX inhibitors, NS398 and aspirin. The AA metabolites, PGD(2) and PGJ(2), but not PGE(2) or PGF(2alpha), reduced the viability of the human HL60 and Jurkat leukemia cells according to the MTT assay and LDH release assay. Apoptotic characteristics including DNA fragmentation, apoptotic bodies, and hypodiploid cells were observed in PGD(2)- and PGJ(2)-treated leukemia cells. A dose- and time-dependent induction of caspase 3 protein procession, and PARP and D4-GDI protein cleavage with activation of caspase 3, but not caspase 1, enzyme activity was detected in HL-60 cells treated with PGD(2) or PGJ(2). Additionally, DNA ladders induced by PGD(2) and PGJ(2) were significantly inhibited by the caspase 3 peptidyl inhibitor, Ac-DEVD-FMK, but not by the caspase 1 peptidyl inhibitor, Ac-YVAD-FMK, in accordance with the blocking of caspase 3, PARP, and D4-GDI protein procession. An increase in intracellular peroxide levels by PGD(2) and PGJ(2) was identified by the DCHF-DA assay, and anti-oxidant N-acetyl cysteine (NAC), mannitol (MAN), and tiron significantly inhibited cell death induced by PGD(2) and PGJ(2) by reducing reactive oxygen species (ROS) production. The PGJ(2) metabolites, 15-deoxy-Delta(12,14)-PGJ(2) and Delta(12)-PGJ(2), exhibited effective apoptosis-inducing activity in HL-60 cells through ROS production via activation of the caspase 3 cascade. The proliferator-activated receptor-gamma (PPAR-gamma) agonists, rosiglitazone (RO), troglitazone (TR), and ciglitazone (CI), induced apoptosis in cells which was blocked by the addition of the PPAR-gamma antagonists, GW9662 and BADGE, via blocking of caspase 3 and PARP cleavage. However, neither GW9662 nor BADGE showed any protective effect on PGD(2)- and PGJ(2)-induced apoptosis. A differential apoptotic effect of PGs through ROS production, followed by activation of the caspase 3 cascade, was demonstrated.

Nonsteroidal anti-inflammatory drugs potentiate 1-methyl-4-phenylpyridinium (MPP+)-induced cell death by promoting the intracellular accumulation of MPP+ in PC12 cells

In this study, we investigated the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on 1-methyl-4-phenylpyridinium (MPP(+))-induced cell death in PC12 cells. Coincubation of PC12 cells with indomethacin, ibuprofen, ketoprofen, or diclofenac, but not aspirin or N-[2-(cyclohexyloxy)-4-nitrophenyl]methanosulfonamide (NS-398), significantly potentiated the MPP(+)-induced cell death. In contrast, these NSAIDs had no effect on rotenone-induced cell death. The potentiating actions of these NSAIDs were not suppressed by treatment with phenyl-N-butyl-nitrone, a radical scavenger; N-acetyl-l-cysteine, an antioxidant; Ac-DEVD-CHO, a selective caspase-3 inhibitor; or 2-chloro-5-nitro-N-phenylbenzamide (GW9662), a selective antagonist of peroxisome proliferator-activated receptor gamma. Furthermore, we observed that DNA fragmentation, which is one of the hallmarks of apoptosis, was not induced by coincubation with MPP(+) and NSAIDs. We confirmed that coincubation of PC12 cells with 30 microM MPP(+) and 100 microM indomethacin, ibuprofen, ketoprofen, or diclofenac led to a significant increase in the accumulation of intracellular MPP(+) compared with incubation with 30 microM MPP(+) alone. In addition, these NSAIDs markedly reduced the efflux of MPP(+) from PC12 cells. (3-(3-(2-(7-Chloro-2-quinolinyl) ethenyl) phenyl ((3-dimethyl amino-3oxo-propyl) thio) methyl) propanoic acid (MK 571), which is an inhibitor of multidrug resistance proteins (MRPs), mimicked the NSAIDs-induced effects, increasing cell toxicity and promoting the accumulation of MPP(+). Moreover, some types of MRPs' mRNA were detected in PC12 cells. These results suggest that some NSAIDs might cause a significant increase in the intracellular accumulation of MPP(+) via the suppression of reverse transport by the blockade of MRP, resulting in the potentiation of MPP(+)-induced cell death.

Diclofenac induces apoptosis in hepatocytes

Hepatotoxicity is one of the side effects associated with the administration of diclofenac, a non-steroidal anti-inflammatory drug widely used clinically. The effect of diclofenac on the early events that trigger apoptosis cascade have been evaluated in rat hepatocytes. To do this, early and late apoptotic markers, associated with the pivotal steps of the execution phase, have been evaluated after incubation with the drug. The results show that the apoptotic effect of diclofenac occurs after exposure to sub-cytotoxic concentrations of the drug (maximal non toxic concentration, MNTC, after 24-h treatment was 450 microM), without overlapping with cell necrosis (LDH leakage evaluation). Flow cytometric analysis revealed a time- and dose-dependent increase of apoptotic nuclei with sub-diploid DNA content. Caspase 3 activation (3-5-fold control) was maximal after 12 h of exposure to 350 microM of the drug. The involvement of the mitochondrial permeability transition (MPT) in diclofenac-induced apoptosis was investigated. Cyclosporine A and decylubiquinone, MPT specific inhibitor, prevented the activation of caspase 3, thus showing that diclofenac opened the MPT pore. Treatment of hepatocytes with antioxidants (alpha-tocopherol, N,N-dimethylthiourea, superoxide dismutase) were able to prevent caspase cascade activation by diclofenac, revealing that oxidative stress at the mitochondrial level is involved in MPT induction. Finally, the differential cytotoxic and apoptotic effect produced in hepatocytes and non-metabolizing hepatoma cells suggest that CYP-mediated metabolism of diclofenac apoptosis may be related to the apoptotic effect of the drug.

Studies on the mechanism of caffeine action in alveolar macrophages: caffeine elevates cyclic adenosine monophosphate level and prostaglandin synthesis

We have previously reported that the effects of caffeine on alveolar macrophages are dose-dependent; thus, at low concentrations caffeine prevents apoptosis and at moderate concentrations, the cells proceed into apoptosis. In the current study, the mechanism of caffeine action via prostaglandin synthesis and cyclic adenosine monophosphate (cAMP) was investigated using moderate concentrations of caffeine. The results show that the combination of caffeine with indomethacin, an inhibitor of prostaglandin synthesis, mediated caffeine's effect by increasing cellular viability and lowering superoxide anion production and DNA fragmentation. However, addition of exogenous prostaglandin E2 (PGE2) to the culture in the presence of caffeine had the opposite effect, in which the viability was decreased and anion superoxide production was increased. Incubation of macrophages with exogenous dibutyryl cAMP showed nearly similar effects to caffeine. At low concentrations (<50 micromol/L), higher viability and lower superoxide production pattern were evident and at higher concentrations (>50 micromol/L) the cells proceeded into apoptosis. Therefore, it is suggested that caffeine exerts its effects on macrophages by altering cAMP level and prostaglandin synthesis.

Physiopathologie des lésions gastro-duodénales induites par les anti-inflammatoires non stéroïdiens

The pathogenesis of the gastroduodenal lesions induced by non-steroidal anti-inflammatory drugs and aspirin is primarily caused by a reduction in mucosal blood flow, which is the consequence of inhibition of cyclooxygenase-producing vasodilator prostaglandins. The subsequent phase is adherence of leukocytes to the endothelium, which may depend on cyclooxygenase-2. Endothelial lesions accentuate the fall of mucosal blood flow and promote the inflammatory process in the gastric mucosa. The inflammatory process is amplified by expression of TNFalpha in polymorphonuclears induced by non-steroidal anti-inflammatory drugs. A few days after starting treatment, epithelial proliferation and increased mucosal blood flow, partly dependent on cyclooxygenase-2 and nitric oxide expression, compensates for the damaging process. Selective inhibitors of inducible cyclooxygenase-2 have reduced gastrointestinal toxicity, which could partially be explained by the protection effect of cyclooxygenase-2 on the gastrointestinal mucosa during inflammation or epithelial repair. Selective inhibitors may worsen inflammatory bowel disease. Non-steroidal inflammatory drugs and aspirin, but perhaps not selective inhibitors, increase the mucosal lesions associated with Helicobacter pylori-induced gastritis. Co-administration of selective inhibitors and aspirin leads to gastrointestinal toxicity equivalent to that of non-specific anti-inflammatory drugs.

Diclofenac induces apoptosis in hepatocytes by alteration of mitochondrial function and generation of ROS

Diclofenac is a non-steroidal anti-inflammatory drug that is widely used clinically but side effects associated with the administration of the drug have been reported. The apoptotic effect of the drug has been evaluated in human and rat hepatocytes. Apoptosis was observed after exposure to sub-cytotoxic concentrations of the drug, without overlapping with cell necrosis. Flow cytometric analysis revealed a time- and dose-dependent increase of apoptotic nuclei with sub-diploid DNA content. Caspase 8 and 9 mediate the cell-receptor and the mitochondria-initiated apoptotic pathways, respectively. Inhibition of both caspases prevented activation of downstream caspases, thus indicating that diclofenac at least activates caspase 3 and both effector caspases 8 and 9. The hierarchy of caspase activation by diclofenac was investigated. Analysis of kinetics revealed a simultaneous activation of these caspases that was maximal after 12 hr of exposure to the drug. Inhibitors of MPT, prevented the downstream activation of the caspase cascade, thus showing that diclofenac opened the mitochondrial pore. On the other hand, antioxidants were able to prevent caspase activation by diclofenac, revealing that oxidative stress at the mitochondrial level is in the root of MPT induction and caspase cascade activation. Caspase activation is not mediated by Bid cleavage, suggesting that the cell-receptor pathway seems not to be involved. However, a dose-dependent release of caspase 8 from the mitochondria was observed, indicating that caspase 8 can be processed independently of cell death receptors. Caspases 8 and 9 are very likely the apical caspases in diclofenac-induced apoptosis. In addition, an early dose-dependent increase of bclX(L) expression parallel to the generation of reactive oxygen species in the mitochondria was found. In conclusion, the mitochondrial pathway is very likely the only pathway involved in diclofenac-induced apoptosis, which was related to CYP-mediated metabolism of diclofenac, with the highest apoptotic effect produced by the metabolite 5OH-diclofenac.

A novel antioxidant and antiapoptotic role of omeprazole to block gastric ulcer through scavenging of hydroxyl radical

The mechanism of the antiulcer effect of omeprazole was studied placing emphasis on its role to block oxidative damage and apoptosis during ulceration. Dose-response studies on gastroprotection in stress and indomethacin-induced ulcer and inhibition of pylorus ligation-induced acid secretion indicate that omeprazole significantly blocks gastric lesions at lower dose (2.5 mg/kg) without inhibiting acid secretion, suggesting an independent mechanism for its antiulcer effect. Time course studies on gastroprotection and acid reduction also indicate that omeprazole almost completely blocks lesions at 1 h when acid inhibition is partial. The severity of lesions correlates well with the increased level of endogenous hydroxyl radical (*OH), which when scavenged by dimethyl sulfoxide causes around 90% reduction of the lesions, indicating that *OH plays a major role in gastric damage. Omeprazole blocks stress-induced increased generation of *OH and associated lipid peroxidation and protein oxidation, indicating that its antioxidant role plays a major part in preventing oxidative damage. Omeprazole also prevents stress-induced DNA fragmentation, suggesting its antiapoptotic role to block cell death during ulceration. The oxidative damage of DNA by *OH generated in vitro is also protected by omeprazole or its analogue, lansoprazole. Lansoprazole when incubated in a *OH-generating system scavenges *OH to produce four oxidation products of which the major one in mass spectroscopy shows a molecular ion peak at m/z 385, which is 16 mass units higher than that of lansoprazole (m/z 369). The product shows no additional aromatic proton signal for aromatic hydroxylation in (1)H NMR. The product absorbing at 278 nm shows no alkaline shift for phenols, thereby excluding the formation of hydroxylansoprazole. The product is assigned to lansoprazole sulfone formed by the addition of one oxygen atom at the sulfur center following attack by the *OH. Thus, omeprazole plays a significant role in gastroprotection by acting as a potent antioxidant and antiapoptotic molecule.

Antidepressants, eicosanoids and the prevention and treatment of cancer. A review

Among the mechanisms of carcinogenesis are oncogene synthesis and expression, upregulation of cyclooxygenase, accelerated cell replication, failed apoptosis, viral activation, disruption of signaling pathways, autoimmunity, immunosuppression, angiogenesis and metastasis. All fall within the orbit of eicosanoids and the enzymes that synthesize them. Antidepressants may be of benefit in the prevention and treatment of cancer, as they inhibit the synthesis, antagonize the actions and accelerate the degradation of such eicosanoids as prostaglandins and thromboxanes.

NSAIDs induce both necrosis and apoptosis in guinea pig gastric mucosal cells in primary culture

A major clinical problem encountered with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin is gastropathy. In this study, we examined, using guinea pig gastric mucosal cells in primary culture, how NSAIDs damage gastric mucosal cells. The short-term treatment of cells with high concentrations of indomethacin decreased cell viability in the absence of apoptotic DNA fragmentation, chromatin condensation, or caspase activation. Cells lost membrane integrity with this short-term indomethacin treatment, suggesting that indomethacin induced necrosis under these conditions. In contrast, the long-term treatment of cells with low concentrations of indomethacin decreased cell viability and was accompanied by apoptotic DNA fragmentation, chromatin condensation, and caspase activation. Pretreatment of cells with inhibitors of caspases or protein synthesis suppressed cell death caused by long-term indomethacin treatment, suggesting that apoptosis was induced when the inhibitors were not present. These results imply that NSAIDs cause gastric mucosal damage through both necrosis and apoptosis of gastric mucosal cells.

Apoptosis of rat gastric mucosa and of primary cultures of gastric epithelial cells by indomethacin: role of inducible nitric oxide synthase and interleukin-8

In order to gain insights into indomethacin-induced gastric injury, rats were fed with indomethacin (20 mg/kg), or alternatively, the primary cultures of rat gastric epithelial cells were cultured with different doses of indomethacin (1-1000 microM). Light microscopy, electron microscopy, fluorescence microscopy, TdT-mediated dUTP-biotin nick end labelling staining, ssDNA staining and DNA fragmentation assay were employed to evaluate the levels of gastric injury and apoptosis. Cells expressing inducible nitric oxide synthase (iNOS) and interleukin (IL)-8 were localized at the rat gastric mucosa by immunohistochemistry. Administration of indomethacin to rats caused apoptosis and injury of the gastric mucosal epithelial cells. Indomethacin also induced apoptosis of primary cultures of gastric epithelial cells in a dose-dependent manner. Cells expressing iNOS and IL-8 were detected at and around the sites of gastric injury in the indomethacin-fed rats, but not in the control rats. The induction of apoptosis by indomethacin in the primary cultures of gastric epithelial cells suggests that the direct apoptotic capacity of indomethacin. iNOS and IL-8 may be involved in this process.

Aspirin effects on gastric epithelial cell proliferation and cytokine expression

Aspirin is known to cause gastric injury and to delay ulcer healing. The effects of aspirin on gastric epithelial cell function are heterogeneous; in contrast to injuring the mucosa, aspirin may also act beneficially by inducing adaptation; a mechanism that is poorly understood. We aimed to document the effects of different doses of aspirin on gastric epithelial cell function defined as proliferation, and secretion as well as mRNA expression of cytokines. Furthermore, we studied the effects of aspirin pretreatment on cytokine secretion as a potential element of gastric adaptation. The proliferative activity of three different gastric epithelial cell lines (AGS, KATO III, RGM-1) was assessed by (3)H-thymidine incorporation; secretion of growth factors PDGF-AB and VEGF into culture supernatant was documented by ELISA. mRNA transcripts of both cytokines were quantified by real time RT-PCR. Low doses of aspirin did not alter the proliferative dynamics in two of the three studied cell lines; high doses abolished proliferation. Secretion of PDGF-AB and VEGF increased during the first days of low dose aspirin exposition; higher concentrations led to a depletion of cytokines after an initial liberation in the case of VEGF, mRNA of which was also dose-dependently increased by aspirin. Seven-day pretreatment with low amounts of aspirin did not alter the secretory response of the epithelia caused by higher doses of this drug. The secretion of cytokines and proliferation of gastric epithelial cells are adversely effected by aspirin in a similarly dose-dependent fashion as the intended effects of this drug on platelet function and pain relief.

Protection by polaprezinc, an anti-ulcer drug, against indomethacin-induced apoptosis in rat gastric mucosal cells

Polaprezinc [N-(3-aminopropionyl)-L-histidinato zinc] (PZ), an anti-ulcer drug, is a chelate compound consisting of zinc and L-carnosine. PZ has been shown to prevent gastric mucosal injury. In the present study, we investigated the inhibitory effect of PZ on indomethacin (IND)-induced apoptosis in a rat gastric mucosal cell line, RGM1. Pretreatment with PZ suppressed caspase-3 activation and subsequent apoptosis in the cells exposed to 500 microM IND in a dose-dependent manner, and 50 microM PZ exhibited the maximum inhibitory effect. Among PZ subcomponents, zinc but not L-carnosine played a pivotal role in this antiapoptotic function. PZ did not affect mitochondrial cytochrome c release upstream of caspase-3 activation in the IND-induced apoptotic signal pathway. Treatment with 500 microM IND evidently produced reactive oxygen species (ROS) in RGM1 cells. However, PZ did not scavenge ROS in IND-treated cells. Moreover, N-acetylL-cysteine, a potent antioxidant, inhibited ROS generation but did not suppress apoptosis in RGM1 cells exposed to IND. These observations demonstrate a novel pharmacological action of PZ; i.e., that PZ, and in particular its zinc subcomponent, inhibits apoptosis via inhibition of caspase-3 activation but not antioxidant activity.

Mitochondrial cytochrome c release and caspase-3-like protease activation during indomethacin-induced apoptosis in rat gastric mucosal cells

Indomethacin (IND), a nonsteroidal anti-inflammatory drug, has been known to cause gastric mucosal injury as a side effect. Using a rat gastric mucosal cell line, RGM1, we determined whether apoptosis is involved in IND-mediated gastropathy, and whether caspase activation and mitochondrial cytochrome c release play an important role in producing apoptosis of IND-treated RGM1 cells in the presence of serum. IND caused caspase-3-like protease activation followed by apoptosis in a dose- and time-dependent manner. Caspase-1-like protease activity did not change during IND-induced apoptosis. IND also increased mitochondrial cytochrome c release in a time-dependent fashion. Mitochondrial cytochrome c efflux occurred just before or at the same time as caspase-3-like protease activation, and preceded the increase in apoptotic cell numbers. Z-VAD-FMK, a caspase inhibitor, inhibited both the increase in caspase-3-like protease activity and apoptosis in IND-treated RGM1 cells but did not affect caspase-1-like protease activity or mitochondrial cytochrome c release. These observations suggest that the apoptosis of gastric mucosal cells could be involved in IND-induced gastropathy, that cytochrome c is released from mitochondria into the cytosol during the early phase of IND-mediated apoptosis, and that subsequent activation of caspase-3-like protease, but not caspase-1-like protease, is required for the execution of apoptosis.

Non-steroidal anti-inflammatory drugs and apoptosis in the gastrointestinal tract: potential role of the pentose phosphate pathways

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely prescribed drugs, primarily for treatment of arthritis. NSAIDs can have two effects independent of their anti-inflammatory action. In the stomach and small bowel long term NSAID consumption can lead to ulceration, whereas in the colon NSAID use can regress existing tumours. In this review, we hypothesise that NSAID-induced damage occurs predominantly by promoting apoptosis, involving a number of mechanisms depending on the type and the redox state of the cell. In addition to inhibiting cyclooxygenase (COX) activity, this includes interfering with glucose metabolism through both arms of the pentose phosphate pathways and energy production via glycolysis and oxidative phosphorylation. Shifting the cellular balance from proliferation to apoptosis is probably the most important outcome by which NSAIDs exhibit their differing actions. Understanding how these different pathways can be reconciled and their contribution to the balance between cell birth and cell death is the challenge for the future. The pentose phosphate pathways may provide a pivotal point for understanding links between factors which alter proliferative activity (e.g. COXs), provide energy metabolism (particularly aerobic and anaerobic metabolism of glucose), and change the redox state of the cell leading to apoptosis.

Eicosanoids and the stomach

Eicosanoids are arachidonic acid derivatives that include prostaglandins, thromboxanes, and leukotrienes. During the last three decades, it has become evident that these bioactive lipids play a pivotal role in gastric physiology. The goal of the present review is to describe their involvement in the normal regulation of gastric secretion and gastric motility, as well as in gastric mucosal defense. Their role in gastric mucosal mitogenesis, apoptosis, inflammation, and immune modulatory responses is also discussed.

Reactive oxygen species are involved in the apoptosis induced by nonsteroidal anti-inflammatory drugs in cultured gastric cells

We previously reported the induction of apoptotic DNA fragmentation by nonsteroidal anti-inflammatory drugs (NSAIDs) in cultured rat gastric cells, and indicated that prostaglandin-synthesis is only marginally involved in the apoptotic process. In the present study, we examined whether the generation of reactive oxygen species is critically involved in NSAID-induced apoptosis. Indomethacin, sodium diclofenac, flurbiprofen, zaltoprofen, etodolac, but not mofezolac, enhanced apoptotic DNA fragmentation and mRNA expression for cyclooxygenase-2 in AGS cells, a cell line derived from human gastric epithelium. The apoptotic effect of indomethacin was then confirmed by fluorescent staining of the cells with annexin V. Apoptotic DNA fragmentation induced by indomethacin and flurbiprofen was suppressed by incubation of the cells with the anti-oxidants pyrrolidine dithiocarbamate, diphenyleneiodonium chloride, and N-acetyl-L-cysteine. These two NSAIDs also enhanced release from the cells of 8-isoprostane, a nonenzymatic product by free-radical-mediated peroxidation of arachidonic acid. Further, lucigenin chemiluminescence showed that the intracellular production of reactive oxygen species increased in cells treated with indomethacin. The present data thus indicate a crucial association between the generation of reactive oxygen species and NSAID-induced apoptosis in gastric epithelial cells.

Malignant transformation and antineoplastic actions of nonsteroidal antiinflammatory drugs (NSAIDs) on cyclooxygenase-null embryo fibroblasts

In this study, we use primary embryonic fibroblasts derived from cyclooxygenase-deficient transgenic embryos to further investigate the role of the two cyclooxygenases, cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2), in the process of neoplastic transformation. Cells with either, neither, or both of the cyclooxygenases were transformed by Ha-ras and/or SV40. Our results show that when a cyclooxygenase enzyme is present, the transformed cells have marked increases in COX-2 and/or COX-1 expression. Nevertheless, each type of cell, deficient in either or both cyclooxygenases, can be readily transformed at almost equal efficiency. Different nonsteroidal antiinflammatory drugs (NSAIDs) were used to examine their possible antineoplastic effects on the transformed cells, which have various levels of expression of COX-1 or COX-2. Our results show that NSAIDs suppress the colony formation in soft agar in a dosage-dependent manner in the absence of the cyclooxygenase(s). Thymidine incorporation and apoptosis analyses further demonstrate that the NSAIDs are effective in the cyclooxygenase-null cells. Our findings with cyclooxygenase knockout cells confirm recent reports that some of the antiproliferative and antineoplastic effects of NSAIDs are independent of the inhibition of either COX-1 or COX-2. They also show that transformation is independent of the status of cyclooxygenase expression, suggesting that the involvement of the cyclooxygenases in tumorigenesis may occur at later steps.