NSAIDs enhance proteasomic degradation of survivin, a mechanism of gastric epithelial cell injury and apoptosis

The contemplation of amylose for the delivery of ulcerogenic nonsteroidal anti-inflammatory drugs

This manuscript proposes an innovative approach to mitigate the gastrointestinal adversities linked with nonsteroidal anti-inflammatory drugs (NSAIDs) by exploiting amylose as a novel drug delivery carrier. The intrinsic attributes of V-amylose, such as its structural uniqueness, biocompatibility and biodegradability, as well as its capacity to form inclusion complexes with diverse drug molecules, are meticulously explored. Through a comprehensive physicochemical analysis of V-amylose and ulcerogenic NSAIDs, the plausibility of amylose as a protective carrier for ulcerogenic NSAIDs to gastrointestinal regions is elucidated. This review further discusses the potential therapeutic advantages of amylose-based drug delivery systems in the management of gastric ulcers. By providing controlled release kinetics and enhanced bioavailability, these systems offer promising prospects for the development of more effective ulcer therapies.

Schisandrin B reverses doxorubicin resistance through inhibiting P-glycoprotein and promoting proteasome-mediated degradation of survivin

Acquired drug resistance poses a great challenge in cancer therapy. Drug efflux and anti-apoptotic processes are the most two common mechanisms that confer cancer drug resistance. In this study, we found that Schisandrin B (Sch B), one of the major dibenzocyclooctadiene derivatives extracted from Chinese herbal medicine Schisandrae Chinensis Fructus, could significantly enhance the sensitivity of doxorubicin (DOX)-resistant breast cancer and ovarian cancer cells to DOX. Our results showed that Sch B increased the intracellular accumulation of DOX through inhibiting expression and activity of P-glycoprotein (P-gp). Meanwhile, Sch B could markedly downregulate the expression of anti-apoptotic protein survivin. Overexpression of survivin attenuated the sensitizing effects of Sch B, while silencing of survivin enhanced Sch B-mediated sensitizing effects. Furthermore, Sch B preferentially promoted chymotryptic activity of the proteasome in a concentration-dependent manner, and the proteasome inhibitor MG-132 prevented Sch B-induced survivin downregulation. Taken together, our findings suggest that Sch B could be a potential candidate for combating drug resistant cancer via modulating two key factors that responsible for cancer resistance.

Effective Targeting of the Survivin Dimerization Interface with Small-Molecule Inhibitors

Many oncoproteins are considered undruggable because they lack enzymatic activities. In this study, we present a small-molecule-based anticancer agent that acts by inhibiting dimerization of the oncoprotein survivin, thereby promoting its degradation along with spontaneous apoptosis in cancer cells. Through a combination of computational analysis of the dimerization interface and in silico screening, we identified one compound that induced proteasome-dependent survivin degradation. Analysis of a set of structural analogues led us to identify a lead compound (LQZ-7F), which was effective in blocking the survival of multiple cancer cell lines in a low micromolar concentration range. LQZ-7F induced proteasome-dependent survivin degradation, mitotic arrest, and apoptosis, and it blocked the growth of human tumors in mouse xenograft assays. In addition to providing preclinical proof of concept for a survivin-targeting anticancer agent, our work offers novel in silico screening strategies to therapeutically target homodimeric oncogenic proteins considered undruggable.

Protective activity of crocin against indomethacin-induced gastric lesions in rats

The present study was designed to elucidate the mechanism(s) of the gastro-protective effect of crocin against indomethacin-induced gastric lesions. Crocin or pantoprazole was administered to rats 30 min before indomethacin. Five hours later, the animals were killed and their stomachs were removed and examined macroscopically. Samples of gastric mucosa were collected for microscopic evaluation, mRNA expression of caspase-3, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 was quantified by RT-PCR, and protein levels of COX-1, COX-2, iNOS and caspase-3 were assessed by Western blotting. The pH, volume of gastric effluent and antioxidant activity were measured in 5 separate groups of rats following pylorus ligation. Indomethacin induced significant increases in mRNA and protein expression of iNOS and caspase-3 and increased MDA levels, and reduced the pH of the gastric effluent and protein and mRNA expression of COX-2 and protein expression of COX-1 and mucus content associated with gastric ulceration. Crocin and pantoprazole significantly inhibited mRNA and protein expression of iNOS, caspase-3 and MDA, and reduced mucus content induced by indomethacin. However, unlike pantoprazole, crocin failed to increase COX-1 and pH, but had variable increasing effects on mRNA and protein expression of COX-2. Macroscopic and microscopic observations showed that mucosal erosions induced by indomethacin were significantly inhibited by pantoprazole and crocin. These findings suggest that crocin exerts its gastro-protective effects mainly by inhibition of MDA, reduction in iNOS and caspase-3, and inhibition of the reduction in mucus content induced by indomethacin. Crocin is a novel agent that has potential in the prevention of ulceration induced by NSAIDs.

Omega-3 polyunsaturated fatty acids as an angelus custos to rescue patients from NSAID-induced gastroduodenal damage

Nonsteroidal anti-inflammat ory drugs (NSAIDs) are one of the drug types frequently prescribed for their analgesic, anti-inflammatory, and antithrombotic actions, but carry a risk of major gastroduodenal damage from mild erosive changes to serious ulceration leading to fatal outcomes. From the long history of willow tree bark and its extracts being applied for the relief of pain and fever, the synthesis of acetylsalicylic acid, the development of selective cyclooxygenase 2 inhibitors (coxibs), and the identification of a G-protein-coupled receptor for prostaglandin, the popular combination regimen of an NSAID and a proton pump inhibitor was invented, but development was continued for further improvement. With regard to major NSAID adverse effects, gastrointestinal (GI) and cardiovascular (CV) risks still remained as problems to be solved. In this review, it is shown that n-3 polyunsaturated fatty acid (PUFA) based NSAIDs can be an angelus custos, supported with facts that an intake of essential n-3 PUFAs orchestrates concerted protective actions against two notorious side effects of NSAIDs, the aforementioned GI risk and CV risk of NSAIDs. Since pills containing n-3 PUFAs, omega-3-acid ethyl ester capsules (Lovaza, Omarcor), have already been safely prescribed to prevent atherosclerosis through lessening lipid burdening, the introduction of a drug delivery system such as a gastroretentive form of n-3 PUFA based NSAIDs will highlight newer hope for GI safety under the guarantee of reduced CV risk. Because n-3 PUFAs have been proven to attenuate cytotoxicity, inhibit lipid-raft-associated harmful signaling, and relieve oxidative stress relevant to NSAIDs, n-3 PUFA based NSAIDs will be next-generation GI-safe NSAIDs.

Indomethacin promotes apoptosis in gastric cancer cells through concomitant degradation of Survivin and Aurora B kinase proteins

Regular usage of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with reduced incidence of a variety of cancers. The molecular mechanisms underlying these chemopreventive effects remain poorly understood. This current investigation showed that in gastric cancer cells: (1) Indomethacin treatment enhanced the degradation of chromosomal passenger proteins, Survivin and Aurora B kinase; (2) Indomethacin treatment down-regulated Aurora B kinase activity in a cell cycle-independent fashion; (3) siRNA knockdown of Survivin level promoted Aurora B kinase protein degradation, and vice versa; (4) ectopic overexpression of Survivin blocked reduction of Aurora B kinase level and activity by indomethacin treatment, and vice versa; (5) siRNA knockdown of Aurora B kinase level and AZD1152 inhibition of its activity induced apoptosis, and overexpression of Aurora B kinase inhibited indomethacin-induced apoptosis; (6) indomethacin treatment reduced Aurora B kinase level, coinciding with reduction of Survivin level and induction of apoptosis, in KATO III and HT-29 cells, and in mouse gastric mucosa. A role for Aurora B kinase function in NSAID-induced apoptosis was not previously explored. Thus this report provides better understanding of the molecular mechanisms underlying the anti-cancer effect of NSAIDs by elucidating a significant role for Aurora B kinase in indomethacin-induced apoptosis.

Antiproliferative and apoptotic effects of indomethacin on human retinoblastoma cell line Y79 and the involvement of β-catenin, nuclear factor-κB and Akt signaling pathways

BACKGROUND

To determine in vitro if indomethacin inhibits proliferation and induces apoptosis in human retinoblastoma cell line Y79, and to explore possibly involved signaling pathways.

METHODS

The human retinoblastoma cell line Y79 was cultured with indomethacin at various concentrations (0, 25, 50, 100, 200 and 400 µmol/l). The effect of indomethacin on cell proliferation and apoptosis was examined by the Cell Counting Kit-8 and TUNEL test, respectively. The mRNA level of survivin, β-catenin and Bcl-2 was detected by RT-PCR. The protein level of survivin was measured by ELISA. Western blot was used to analyze β-catenin, nuclear factor (NF)-κB/p65, phosphorylated Akt (pAkt) and total Akt (tAkt) expression in cultured cells.

RESULTS

Indomethacin treatment inhibits proliferation (at concentrations from 25 to 400 µmol/l) and induces apoptosis (at concentrations from 100 to 400 µmol/l) of human retinoblastoma cell line Y79 in a dose-dependent manner. RT-PCR showed that the mRNA expression of Bcl-2 (F = 20.497; p < 0.001) and of β-catenin (F = 14.835; p < 0.001) was significantly different among the treated groups. Survivin mRNA levels remained steady, but its protein levels decreased significantly as measured by ELISA (F = 67.633; p < 0.001). Western blot analysis showed a dose-dependent downregulation of β-catenin (F = 37.411; p < 0.001), NF-κB/p65 (F = 16.302; p < 0.001) and of pAkt (F = 27.700; p < 0.001) after indomethacin treatment, while tAkt protein expression was steady among the groups.

CONCLUSIONS

Treatment with indomethacin can potently suppress proliferation and induce apoptosis in the retinoblastoma Y79 cell line. Wnt/β-catenin, NF-κB and Akt/PKB pathways might be implicated in the process.

Nutrient availability alters the effect of autophagy on sulindac sulfide-induced colon cancer cell apoptosis

Autophagy is a catabolic process by which a cell degrades its intracellular materials to replenish itself. Induction of autophagy under various cellular stress stimuli can lead to either cell survival or cell death via apoptotic and/or autophagic (nonapoptotic) pathways. The NSAID sulindac sulfide induces apoptosis in colon cancer cells. Here, we show that inhibition of autophagy under serum-deprived conditions resulted in significant reductions of sulindac sulfide-induced apoptosis in HT-29 colon cancer cells. In contrast, inhibition of autophagy under conditions where serum is available significantly increased sulindac sulfide-induced apoptosis in HT-29 cells. We previously showed that the apoptosis inhibitor, survivin, plays a role in regulating NSAID-induced apoptosis and autophagic cell death. Here, we show that survivin protein half-life is increased in the presence of autophagy inhibitors under serum-deprived conditions, but not under conditions when serum is available. Thus, the increased levels of survivin may be a factor contributing to inhibition of sulindac sulfide-induced apoptosis under serum-deprived conditions. These results suggest that whether a cell lives or dies due to autophagy induction depends on the balance of factors that regulate both autophagic and apoptotic processes.

Histone deacetylase inhibitor belinostat represses survivin expression through reactivation of transforming growth factor beta (TGFbeta) receptor II leading to cancer cell death

Survivin is a cancer-associated gene that functions to promote cell survival, cell division, and angiogenesis and is a marker of poor prognosis. Histone deacetylase inhibitors induce apoptosis and re-expression of epigenetically silenced tumor suppressor genes in cancer cells. In association with increased expression of the tumor suppressor gene transforming growth factor β receptor II (TGFβRII) induced by the histone deacetylase inhibitor belinostat, we observed repressed survivin expression. We investigated the molecular mechanisms involved in survivin down-regulation by belinostat downstream of reactivation of TGFβ signaling. We identified two mechanisms. At early time points, survivin protein half-life was decreased with its proteasomal degradation. We observed that belinostat activated protein kinase A at early time points in a TGFβ signaling-dependent mechanism. After longer times (48 h), survivin mRNA was also decreased by belinostat. We made the novel observation that belinostat mediated cell death through the TGFβ/protein kinase A signaling pathway. Induction of TGFβRII with concomitant survivin repression may represent a significant mechanism in the anticancer effects of this drug. Therefore, patient populations exhibiting high survivin expression with epigenetically silenced TGFβRII might potentially benefit from the use of this histone deacetylase inhibitor.

Suppression of growth arrest and DNA damage-inducible 45alpha expression confers resistance to sulindac and indomethacin-induced gastric mucosal injury

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as sulindac and indomethacin are a major cause of gastric erosions and ulcers. Induction of apoptosis by NSAIDs is an important mechanism involved. Understanding how NSAIDs affect genes that regulate apoptosis is useful for designing therapeutic or preventive strategies and for evaluating the efficacy of safer drugs being developed. We investigated whether growth arrest and DNA damage-inducible 45alpha (GADD45alpha), a stress signal response gene involved in regulation of DNA repair and induction of apoptosis, plays a part in NSAID-induced gastric mucosal injury and apoptosis in vivo in mice and in vitro in cultured human AGS and rat RGM-1 gastric epithelial cells. Intraperitoneal administration of sulindac and indomethacin both resulted in up-regulation of GADD45alpha expression and induction of significant injury and apoptosis in gastric mucosa of wild-type mice. GADD45alpha(-/-) mice were markedly more resistant to both sulindac- and indomethacin-induced gastric mucosal injury and apoptosis than wild-type mice. Sulindac sulfide and indomethacin treatments also concentration-dependently increased GADD45alpha expression and apoptosis in AGS and RGM-1 cells. Antisense suppression of GADD45alpha expression significantly reduced sulindac and indomethacin-induced activation of caspase-9 and apoptosis in AGS cells. Pretreatments with exogenous prostaglandins and small interfering RNA suppression of cyclooxygenase (COX)-1 and -2 did not affect up-regulation of GADD45alpha by sulindac sulfide and indomethacin in AGS cells. These findings indicate that GADD45alpha up-regulation is a COX-independent mechanism that is required for induction of severe gastric mucosal apoptosis and injury by NSAIDs, probably via a capase-9-dependent pathway of programmed cell death.

Targeting Hsp90 with small molecule inhibitors induces the over-expression of the anti-apoptotic molecule, survivin, in human A549, HONE-1 and HT-29 cancer cells

Background

Survivin is a dual functioning protein. It inhibits the apoptosis of cancer cells by inhibiting caspases, and also promotes cancer cell growth by stabilizing microtubules during mitosis. Since the molecular chaperone Hsp90 binds and stabilizes survivin, it is widely believed that down-regulation of survivin is one of the important therapeutic functions of Hsp90 inhibitors such as the phase III clinically trialed compound 17-AAG. However, Hsp90 interferes with a number of molecules that up-regulate the intracellular level of survivin, raising the question that clinical use of Hsp90 inhibitors may indirectly induce survivin expression and subsequently enhance cancer anti-drug responses. The purpose of this study is to determine whether targeting Hsp90 can alter survivin expression differently in different cancer cell lines and to explore possible mechanisms that cause the alteration in survivin expression.

Results

Here, we demonstrated that Hsp90 inhibitors, geldanamycin and 17-AAG, induced the over-expression of survivin in three different human cancer cell lines as shown by Western blotting. Increased survivin mRNA transcripts were observed in 17-AAG and geldanamycin-treated HT-29 and HONE-1 cancer cells. Interestingly, real-time PCR and translation inhibition studies revealed that survivin was over-expressed partially through the up-regulation of protein translation instead of gene transcription in A549 cancer cells. In addition, 17-AAG-treated A549, HONE-1 and HT-29 cells showed reduced proteasomal activity while inhibition of 26S proteasome activity further increased the amount of survivin protein in cells. At the functional level, down-regulation of survivin by siRNA further increased the drug sensitivity to 17-AAG in the tested cancer cell lines.

Conclusions

We showed for the first time that down-regulation of survivin is not a definite therapeutic function of Hsp90 inhibitors. Instead, targeting Hsp90 with small molecule inhibitors will induce the over-expression of survivin in certain cancer cell lines and subsequently enhances the ability of cell survival in drug-treated situations. The current study suggests that dual inhibition of Hsp90 and survivin may be warranted.

Up-regulation of GADD45alpha expression by NSAIDs leads to apoptotic and necrotic colon cancer cell deaths

Growth arrest and DNA damage inducible 45 alpha (GADD45alpha) is a central player in mediating apoptosis induced by a variety of stress stimuli and genotoxic agents. Regular usage of nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin and sulindac is associated with reduced risk for various cancers, including colon cancer. The role of GADD45alpha in NSAID-induced colon cancer cell cytotoxicity is unknown. In this study, we report that indomethacin and sulindac sulfide treatments up-regulate GADD45alpha mRNA expression and protein levels in colon cancer HT-29, RKO and Caco-2 cells. This up-regulation of GADD45alpha is accompanied by necrotic cell death and apoptosis. Anti-sense suppression of GADD45alpha expression inhibited indomethacin and sulindac sulfide-induced necrotic cell death and apoptosis. These findings confirm a role for GADD45alpha in NSAID-induced cytotoxicity, a mechanism for the anti-neoplastic effect of NSAIDs in colon tumorigenesis and cancer growth.

Review article: cellular and molecular mechanisms of NSAID-induced peptic ulcers

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are some of the most prescribed drugs worldwide and have now probably overtaken Helicobacter pylori as the most common cause of gastrointestinal injury in Western countries. Further understanding of the pathogenesis of NSAID-induced ulcers is important to enable the development of novel and effective preventive strategies.

AIMS

To provide an update on recent advances in our understanding of the cellular and molecular mechanisms involved in the development of NSAID-induced ulcers.

METHODS

A Medline search was performed to identify relevant literature using search terms including 'nonsteroidal anti-inflammatory drugs, aspirin, gastric ulcer, duodenal ulcer, pathogenesis, pharmacogenetics'.

RESULTS

The mechanisms of NSAID-induced ulcers can be divided into topical and systemic effects and the latter may be prostaglandin-dependent (through COX inhibition) or prostaglandin-independent. Genetic factors may play an important role in determining individual predisposition.

CONCLUSIONS

The pathogenesis of NSAID-induced peptic ulcers is complex and multifactorial. Recent advances in cellular and molecular biology have highlighted the importance of various prostaglandin-independent mechanisms. Pharmacogenetic studies may provide further insights into the pathogenetic mechanisms of NSAID-induced ulcers and help identify patients at increased risk.

Pancreatic secretory trypsin inhibitor is a major motogenic and protective factor in human breast milk

Colostrum is the first milk produced after birth and is rich in immunoglobulins and bioactive molecules. We examined whether human colostrum and milk contained pancreatic secretory trypsin inhibitor (PSTI), a peptide of potential relevance for mucosal defense and, using in vitro and in vivo models, determined whether its presence influenced gut integrity and repair. Human milk was collected from individuals over various times from parturition and PSTI concentrations determined with the use of immunoassay. Human milk samples were analyzed for proliferation and promigratory activity (wounded monolayers) and antiapoptotic activity (caspase-3 activity) with the use of intestinal HT29 cells with or without neutralizing antibodies to PSTI and epidermal growth factor (EGF). Rats were restrained and given indomethacin to induce gastric injury. Effect of gavage with human breast milk with or without neutralizing antibodies on amount of injury were compared with animals receiving a commercial formula feed. PSTI is secreted into human milk, with colostrum containing a much higher concentration of PSTI than human milk obtained later. Human milk stimulated migration and proliferation about threefold and reduced indomethacin-induced apoptosis by about 70-80%. Sixty-five percent of the migratory effect of human milk could be removed by immunoneutralization of PSTI. PSTI worked synergistically with EGF in mediating these effects. Gastric damage in rats was reduced by about 75% in the presence of human milk and was more efficacious than the formula feed (P<0.001). Protective effects of the milk were reduced by about 60% by PSTI immunoneutralization. We concluded that PSTI is secreted into human milk at concentrations that have probable pathophysiological relevance.

Indomethacin causes renal epithelial cell injury involving Mcl-1 down-regulation

Nonsteroidal anti-inflammatory drugs (NSAIDs) exert anti-tumor action in a variety of cancer cells. However, several treatment side effects such as gastrointestinal injury, cardiovascular toxicity, and acute renal failure limit their clinical use. We found that indomethacin caused renal epithelial cell injury independently of cyclooxygenase inhibition. Indomethacin treatment was associated with the disruption of mitochondrial transmembrane potential, release of cytochrome c, down-regulation of Bcl-2 and Mcl-1, upregulation of Bax, and elevation of caspases activity. Enhanced Mcl-1 but not Bcl-2 expression alleviated indomethacin-increased caspase-3 activity. Down-regulation of Akt-related and signal transducer and activator of transcription (STAT-3)-related pathways was found in indomethacin-treated cells. Pharmacological and genetic studies revealed a potential mechanistic link between Akt/Mcl-1 and STAT-3/Mcl-1 signaling pathways and indomethacin-induced cytotoxicity. Mcl-1 is a determinant molecule for the induction of epithelial cell injury caused by indomethacin. Therefore, the maintenance of Mcl-1 levels is important for prevention of renal epithelial cell injury and apoptosis.

Gastroduodenal mucosal defense

PURPOSE OF REVIEW

The gastrointestinal tract has developed multiple mechanisms of protection from intrinsic and extrinsic sources of injury, including but not limited to drugs, ischemic/reperfusion injuries, and infections such as Helicobacter pylori. We review recent developments in host defense against Helicobacter pylori, duodenal bicarbonate secretion, protection from nonsteroidal anti-inflammatory drug induced gastrointestinal injury, and apoptosis, as well as newer therapies.

RECENT FINDINGS

Leptin and survivin confer protection against ethanol and indomethacin induced injury. Mucin-1, a cell surface mucin, is an important barrier to gastrointestinal infection. Prostaglandin E(2), Escherichia coli heat-stable enterotoxin, orexins, and carbonated beverages stimulate duodenal bicarbonate secretion.

SUMMARY

Gastroduodenal mucosal defense is a dynamic process, and further insights into these defense mechanisms have and will lead to safer and more effective treatments.