Nonsteroidal antiinflammatory drugs inhibit the proliferation of colon adenocarcinoma cells: effects on cell cycle and apoptosis

Effectiveness of long-term low-dose aspirin in the prevention of gastric cancer after Helicobacter pylori eradication: study design and rationale of Ardabil gastric cancer randomized placebo-controlled prevention trial (AGCPT)

BACKGROUND

In addition to Helicobacter pylori (H. pylori) infection eradication, some medications, including aspirin, metformin, and statins, have been suggested to have protective effects against gastric cancer (GC) development in observational studies. We launched the Ardabil gastric cancer randomized placebo-controlled prevention trial (AGCPT) to evaluate the effectiveness of long-term low-dose aspirin use for the prevention of development and mortality of GC after H. pylori eradication.

METHODS/DESIGN

AGCPT is a prospective population-based double-blind, randomized clinical trial. The study sample was targeted at 21,000 participants aged from 35 to 70 years old, both sexes, in Ardabil, a province in northwest Iran with relatively high rates of GC incidence and mortality. All eligible participants were initially tested for H. pylori infection using a H. pylori stool antigen test. Participants with positive tests undergo H. pylori eradication by standard treatment regimens. All participants with a negative test and those with a positive test with a subsequent confirmed H. pylori eradication test were entered into the intervention phase. In the intervention phase, participants were allocated randomly into either the treatment (daily oral consumption of 81 mg enteric-coated aspirin tablets) arm or the control (placebo) arm using permuted balanced blocks. Subjects will be followed for an average period of 10 years to evaluate the incidence and mortality rates of GC.

DISCUSSION

In addition to preventing other diseases like cardiovascular events, aspirin may prevent GC incidence and mortality. AGCPT will investigate the difference between the two study arms in the proportion of the cumulative incidence and mortality rates of GC. The study's results may help policymakers and researchers update the strategies for GC prevention.

TRIAL REGISTRATION

This trial with the registry name of "The effect of Low-dose Aspirin in the Prevention of Gastric Cancer" was registered in the Iranian Registry of Clinical Trials, IRCT.ir, under the identifier IRCT201105082032N3. Registered on April 21, 2017.

Pharmacokinetics of aspirin: evaluating shortcomings in the literature

INTRODUCTION

Aspirin is known for its therapeutic benefits in preventing strokes and relieving pain. However, it is toxic to some individuals, and the biological mechanisms causing toxicity are unknown. Limited literature is available on the role of glycine conjugation as the principal pathway in aspirin detoxification. Previous studies have quantified this two-step enzyme reaction as a singular enzymatic process. Consequently, the individual contributions of these enzymes to the kinetics remain unclear.

AREAS COVERED

This review summarized the available information on the pharmacokinetics and detoxification of aspirin by the glycine conjugation pathway. Literature searches were conducted using Google Scholar and the academic journal databases accessible through the North-West University Library. Furthermore, the factors affecting interindividual variation in aspirin metabolism and what is known regarding aspirin toxicity were discussed.

EXPERT OPINION

The greatest drawback in understanding the pharmacokinetics of aspirin is the limited information available on the substrate preference of the xenobiotic ligase (ACSM) responsible for activating salicylate to salicyl-CoA. Furthermore, previous pharmacokinetic studies did not consider the contribution of other substrates from the diet or genetic variants, to the detoxification rate of glycine conjugation. Impaired glycine conjugation might contribute to adverse health effects seen in Reye's syndrome and cancer.

Additive Cytotoxic and Colony-Formation Inhibitory Effects of Aspirin and Metformin on PI3KCA-Mutant Colorectal Cancer Cells

Human malignancies are one of the major health-related issues throughout the world and are anticipated to rise in the future. Despite huge investments made in anticancer drug development, limited success has been obtained and the average number of FDA approvals per year is declining. So, an increasing interest in drug repurposing exists. Metformin (MET) and aspirin (ASP) possess anticancer properties. This work aims to test the effect of these two drugs in combination on colorectal cancer (CRC) cells in vitro. The effects of MET and/or ASP on cell proliferation, viability, migratory ability, anchorage-independent growth ability (colony formation), and nutrient uptake were determined in two (HT-29 and Caco-2) human CRC cell lines. Individually, MET and ASP possessed antiproliferative, cytotoxic, and antimigratory effects and reduced colony formation in HT-29 cells (BRAF- and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PI3KCA)-mutant), although MET did not affect either 3H-deoxy-D-glucose or 14C-butyrate uptake and lactate production, and ASP caused only a small decrease in 14C-butyrate uptake. Moreover, in these cells, the combination of MET and ASP resulted in a tendency to an increase in the cytotoxic effect and in a potentiation of the inhibitory effect on colony formation, although no additive antiproliferative and antimigratory effects, and no effect on nutrient uptake and lactate production were observed. In contrast, MET and ASP, both individually and in combination, were almost devoid of effects on Caco-2 cells (BRAF- and PI3KCA-wild type). We suggest that inhibition of PI3K is the common mechanism involved in the anti-CRC effect of both MET, ASP and their combination and, therefore, that the combination of MET + ASP may especially benefit PI3KCA-mutant CRC cases, which currently have a poor prognostic.

The Potential Preventive and Therapeutic Roles of NSAIDs in Prostate Cancer

Prostate cancer (PC) is the second most common type of cancer and the leading cause of death among men worldwide. Preventing the progression of cancer after treatments such as radical prostatectomy, radiation therapy, and hormone therapy is a major concern faced by prostate cancer patients. Inflammation, which can be caused by various factors such as infections, the microbiome, obesity and a high-fat diet, is considered to be the main cause of PC. Inflammatory cells are believed to play a crucial role in tumor progression. Therefore, nonsteroidal anti-inflammatory drugs along with their effects on the treatment of inflammation-related diseases, can prevent cancer and its progression by suppressing various inflammatory pathways. Recent evidence shows that nonsteroidal anti-inflammatory drugs are effective in the prevention and treatment of prostate cancer. In this review, we discuss the different pathways through which these drugs exert their potential preventive and therapeutic effects on prostate cancer.

Indomethacin Induces Spermidine/Spermine-N1-Acetyltransferase-1 via the Nucleolin-CDK1 Axis and Synergizes with the Polyamine Oxidase Inhibitor Methoctramine in Lung Cancer Cells

Indomethacin is a non-selective NSAID used against pain and inflammation. Although cyclooxygenase (COX) inhibition is considered indomethacin's primary action mechanism, COX-independent ways are associated with beneficial effects in cancer. In colon cancer cells, the activation of the peroxisome proliferator-activated receptor-γ (PPAR-γ) is related to the increase in spermidine/spermine-N1-acetyltransferase-1 (SSAT-1), a key enzyme for polyamine degradation, and related to cell cycle arrest. Indomethacin increases the SSAT-1 levels in lung cancer cells; however, the mechanism relying on the SSAT-1 increase is unclear. Thus, we asked for the influence of the PPAR-γ on the SSAT-1 expression in two lung cancer cell lines: H1299 and A549. We found that the inhibition of PPAR-γ with GW9662 did not revert the increase in SSAT-1 induced by indomethacin. Because the mRNA of SSAT-1 suffers a pre-translation retention step by nucleolin, a nucleolar protein, we explored the relationship between indomethacin and the upstream translation regulators of SSAT-1. We found that indomethacin decreases the nucleolin levels and the cyclin-dependent kinase 1 (CDK1) levels, which phosphorylates nucleolin in mitosis. Overexpression of nucleolin partially reverts the effect of indomethacin over cell viability and SSAT-1 levels. On the other hand, Casein Kinase, known for phosphorylating nucleolin during interphase, is not modified by indomethacin. SSAT-1 exerts its antiproliferative effect by acetylating polyamines, a process reverted by the polyamine oxidase (PAOX). Recently, methoctramine was described as the most specific inhibitor of PAOX. Thus, we asked if methoctramine could increase the effect of indomethacin. We found that, when combined, indomethacin and methoctramine have a synergistic effect against NSCLC cells in vitro. These results suggest that indomethacin increases the SSAT-1 levels by reducing the CDK1-nucleolin regulatory axis, and the PAOX inhibition with methoctramine could improve the antiproliferative effect of indomethacin.

NSAIDs Naproxen, Ibuprofen, Salicylate, and Aspirin Inhibit TRPM7 Channels by Cytosolic Acidification

Non-steroidal anti-inflammatory drugs (NSAIDs) are used for relieving pain and inflammation accompanying numerous disease states. The primary therapeutic mechanism of these widely used drugs is the inhibition of cyclooxygenase 1 and 2 (COX1, 2) enzymes that catalyze the conversion of arachidonic acid into prostaglandins. At higher doses, NSAIDs are used for prevention of certain types of cancer and as experimental treatments for Alzheimer’s disease. In the immune system, various NSAIDs have been reported to influence neutrophil function and lymphocyte proliferation, and affect ion channels and cellular calcium homeostasis. Transient receptor potential melastatin 7 (TRPM7) cation channels are highly expressed in T lymphocytes and are inhibited by Mg²⁺, acidic pH, and polyamines. Here, we report a novel effect of naproxen, ibuprofen, salicylate, and acetylsalicylate on TRPM7. At concentrations of 3–30mM, they reversibly inhibited TRPM7 channel currents. By measuring intracellular pH with the ratiometric indicator BCECF, we found that at 300μM to 30mM, these NSAIDs reversibly acidified the cytoplasm in a concentration-dependent manner, and propose that TRPM7 channel inhibition is a consequence of cytosolic acidification, rather than direct. NSAID inhibition of TRPM7 channels was slow, voltage-independent, and displayed use-dependence, increasing in potency upon repeated drug applications. The extent of channel inhibition by salicylate strongly depended on cellular PI(4,5)P₂ levels, as revealed when this phospholipid was depleted with voltage-sensitive lipid phosphatase (VSP). Salicylate inhibited heterologously expressed wildtype TRPM7 channels but not the S1107R variant, which is insensitive to cytosolic pH, Mg²⁺, and PI(4,5)P₂ depletion. NSAID-induced acidification was also observed in Schneider 2 cells from Drosophila, an organism that lacks orthologous COX genes, suggesting that this effect is unrelated to COX enzyme activity. A 24-h exposure to 300μM–10mM naproxen resulted in a concentration-dependent reduction in cell viability. In addition to TRPM7, the described NSAID effect would be expected to apply to other ion channels and transporters sensitive to intracellular pH.

The multiple effects of aspirin in prostate cancer patients

Aspirin is a commonly used medication with anti-inflammatory and analgesic properties, and it is widely used to reduce the risk of ischaemic heart disease-related events and/or cerebrovascular accidents. However, there is also evidence from epidemiological and interventional studies to suggest that regular aspirin use can reduce the risk of prostate cancer development and progression, and can reduce the risk of disease recurrence following anti-prostate cancer therapy. Aspirin use in African-American men is associated with a reduced incidence of advanced PCa and reduced disease recurrence, and there is evidence from other studies of an association between regular aspirin use and decreased PCa-related mortality. The cyclooxygenase-2 enzyme inhibited by Aspirin and other NSAIDs, and which catalyses prostaglandin synthesis and mediates inflammation, is overexpressed in prostate cancer, therefore inhibition of cyclooxygenase-2 may have direct, and indirect, therapeutic effects. This review explores the evidence suggesting that aspirin use can modify prostate cancer biology and disease characteristics, and explores the potential mechanisms underpinning the observed associations between aspirin use and modification of prostate cancer risk. It also summarises the potential for adjuvant aspirin use to combine with other therapeutic approaches such as radical surgery and radiotherapy.

NSAIDs-dependent adaption of the mitochondria-proteasome system in immortalized human cardiomyocytes

The progressive consumption growth of non-steroidal anti-inflammatory drugs (NSAIDs) has progressively raised the attention toward the gastrointestinal, renal, and cardiovascular toxicity. Increased risk of cardiovascular diseases was strictly associated with the usage of COX-2 selective NSAIDs. Other studies allowed to clarify that the cardiovascular risk is not limited to COX-2 selective but also extended to non-selective NSAIDs, such as Diclofenac and Ketoprofen. To date, although a less favorable cardiovascular risk profile for Diclofenac as compared to Ketoprofen is reported, the mechanisms through which NSAIDs cause adverse cardiovascular events are not entirely understood. The present study aimed to evaluate the effects of Ketoprofen in comparison with Diclofenac in immortalized human cardiomyocytes. The results obtained highlight the dose-dependent cardiotoxicity of Diclofenac compared to Ketoprofen. Despite both drugs induce the increase in ROS production, decrease of mitochondrial membrane potential, and proteasome activity modulation, only Diclofenac exposure shows a marked alteration of these intracellular parameters, leading to cell death. Noteworthy, Diclofenac decreases the proteasome 26S DC and this scenario may be dependent on the intracellular overload of oxidized proteins. The data support the hypothesis that immortalized human cardiomyocytes exposed to Ketoprofen are subjected to tolerable stress events, conversely Diclofenac exposition triggers cell death.

Salicylate suppresses the oncogenic hyaluronan network in metastatic breast cancer cells

The oncogenic role of hyaluronan in several aspects of tumor biology has been well established. Recent studies by us and others suggest that inhibition of hyaluronan synthesis could represent an emerging therapeutic approach with significant clinical relevance in controlling different breast cancer subtypes, including triple-negative breast cancer. Epidemiological and preclinical studies have revealed the therapeutic potential of aspirin (acetyl salicylate), a classical anti-inflammatory drug, in patients with cancer. However, the underlying molecular mechanisms remain unknown. The present study demonstrates that salicylate, a break down product of aspirin in vivo, alters the organization of hyaluronan matrices by affecting the expression levels of hyaluronan synthesizing (HAS1, 2, 3) and degrading (HYAL-1, -2) enzymes, and that of hyaluronan receptor CD44. In particular, salicylate was found to potently activate AMPK, a kinase known to inhibit HAS2 activity, and caused a dose-dependent decrease of cell associated (intracellular and membrane-bound) as well as secreted hyaluronan, followed by the down-regulation of HAS2 and the induction of HYAL-2 and CD44 in metastatic breast cancer cells. These salicylate-mediated effects were associated with the redistribution of CD44 and actin cytoskeleton that resulted in a less motile cell phenotype. Interestingly, salicylate inhibited metastatic breast cancer cell proliferation and growth by inducing cell growth arrest without signs of apoptosis as evidenced by the substantial decrease of cyclin D1 protein and the absence of cleaved caspase-3, respectively. Collectively, our study offers a possible direction for the development of new matrix-based targeted treatments of metastatic breast cancer subtypes via inhibition of hyaluronan, a pro-angiogenic, pro-inflammatory and tumor promoting glycosaminoglycan.

Multi-Targeting Anticancer Agents: Rational Approaches, Synthetic Routes and Structure Activity Relationship

We live in a world with complex diseases such as cancer which cannot be cured with one-compound one-target based therapeutic paradigm. This could be due to the involvement of multiple pathogenic mechanisms. One-compound-various-targets stratagem has become a prevailing research topic in anti-cancer drug discovery. The simultaneous interruption of two or more targets has improved the therapeutic efficacy as compared to the specific targeted based therapy. In this review, six types of dual targeting agents along with some interesting strategies used for their design and synthesis are discussed. Their pharmacology with various types of the molecular interactions within their specific targets has also been described. This assemblage will reveal the recent trends and insights in front of the scientific community working in dual inhibitors and help them in designing the next generation of multi-targeted anti-cancer agents.

Single cell transcriptomic analysis of human mesenchymal stem cells reveals limited heterogeneity

Mesenchymal stem cells (MSCs) are a population of multipotent cells with a superior ability to promote tissue repair by regulating regeneration and inflammation. Effective application of MSCs in disease treatment relies on the production of relatively homogeneous cell population. However, the cellular heterogeneity and the differentiation trajectories of in vitro expanded MSCs remain largely unclear. We profiled the transcriptomes of 361 single MSCs derived from two umbilical cords (UC-MSCs). These UC-MSCs were harvested at different passages and stimulated with or without inflammatory cytokines. Weighted gene correlation network analysis revealed that UC-MSCs surprisingly possess only limited heterogeneity, regardless of donors, and passages. We also found that upon pretreatment with inflammatory cytokines (IFNγ and TNFα), a classical strategy that can improve the efficiency of MSC-based therapy, MSCs exhibited uniformed changes in gene expression. Cell cycle-based principal component analysis showed that the limited heterogeneity identified in these UC-MSCs was strongly associated with their entrance into the G2/M phase. This was further proven by the observation that one featured gene, CD168, was expressed in a cell cycle-dependent manner. When CD168^high UC-MSCs were sorted and cultured in vitro, they again showed similar CD168 expression patterns. Our results demonstrated that in vitro expanded UC-MSCs are a well-organized population with limited heterogeneity dominated by cell cycle status. Thus, our studies provided information for standardization of MSCs for disease treatment.

The effects of vitamins and selenium mixture or ranitidine against small intestinal injury induced by indomethacin in adult rats

This study was aimed at investigating morphological and biochemical efficacies of antioxidants on indomethacin-induced small intestinal damage in rats. Group I: control animals (negative control) given only placebo, Group II: (positive control) are animals orally given combination of antioxidants [vitamin C (Vit C), vitamin E (Vit E), β-carotene and sodium selenite (Se)] daily for 3 days, Group III: Rats were given only indomethacin, Group IV: animals were given of antioxidants combination for 3 days, last dose was given 2 hr before the administration of indomethacin. Group V: Animals receiving ranitidine for 3 days (second positive control). Group VI: Animals received ranitidine for 3 days, last dose was given 2 hr before to indomethacin administration. Indomethacin caused degenerative morphological and biochemical changes, which were reversed on antioxidants administration. As a result, we propose that antioxidants combination would be therapeutically beneficial for treating indomethacin-induced lesions of small intestine. PRACTICAL APPLICATIONS: Indomethacin is a widely preferred nonsteroidal anti-inflammatory drug (NSAID) but its side effects on gastrointestinal system are well known. Indomethacin also causes production of reactive oxygen species. Antioxidants and selenium has protective effects. According to the results of this study, antioxidants and selenium can be used as a food supplement for preventing NSAID-induced side effects and toxicity.

Co-assembled supramolecular hydrogels of doxorubicin and indomethacin-derived peptide conjugates for synergistic inhibition of cancer cell growth

Co-assembly of doxorubicin and a NSAID-based self-assembling peptide conjugate promotes synergistic inhibition of cancer cell growth.

Survivin as a potential therapeutic target of acetylsalicylic acid in pituitary adenomas

Acetylsalicylic acid (ASA) is known as a cancer preventing agent, but there is no data available regarding the effect of ASA on pituitary cells.

We investigated 66 nonfunctioning (NFPA) and growth hormone (GH)-producing adenomas and 15 normal pituitary samples. Functional assays (cell viability, proliferation, flow cytometry cell cycle analysis, caspase-3 activation and DNA degradation) were applied to explore the effect of ASA, YM155 (survivin inhibitor), survivin-targeting siRNA and TNF-related apoptosis-inducing ligand (TRAIL) in RC-4B/C and GH3 cells. Pituitary adenoma xenografts were generated in immunocompromised mice.

We found that survivin was overexpressed and TRAIL was downregulated in NFPAs compared to normal pituitary tissue. ASA decreased proliferation but did not induce apoptosis in pituitary cells. Additionally, ASA treatment decreased cells in S phase and increased cells in G2/M phase of the cell cycle. Inhibition of survivin using an inhibitor or siRNA-mediated silencing reversed the ASA-induced growth inhibition partially. In addition, we also found survivin-independent effects of ASA on the cell cycle that were mediated through inhibition of cyclin A, cyclin dependent kinase 2 (CDK2) and phospho-CDK2. We also aimed to test the effect of acetylsalicylic acid in an animal model using RC-4 B/C cells, but in contrast to GH3 cells, RC-4 B/C cells failed to adhere and grow a xenograft.

We concluded that ASA inhibited the growth of pituitary adenoma cells. Survivin inhibition is a key mechanism explaining its antineoplastic effects. Our results suggest that inhibition of survivin with small molecules or ASA could serve as potential therapeutic agents in NFPA.

Gellan gum macrobeads loaded with naproxen: The impact of various naturally derived polymers on pH-dependent behavior

Aims

After oral administration, naproxen generates several side-effects related to stomach malfunction. Undoubtedly, the enteric dosage forms with naproxen can be considered as safer. Moreover, since it has been evidenced that development and growth of colorectal cancer is related to the presence of cyclooxygenase, naproxen is investigated in terms of the tumor prevention. The aim of the present work was to formulate and evaluate the properties of novel naproxen-loaded macrobeads, made on the basis of low-acyl gellan gum and its blends with carrageenans, guar gum, cellulose sulfate, and dextran sulfates.

Method

Seven formulations were prepared by ionotropic gelation. The morphology of the dried beads was evaluated by scanning electron microscopy. The next step focused on Raman spectroscopy and thermal analysis of naproxen, polymers, and the beads. Next, the swelling behavior was examined in three acceptor fluids at pH = 1.2; 4.5, and 7.4. The beads were evaluated regarding naproxen content and encapsulation efficiency. The last stage of the work concerned the drug release studies.

Results

Addition of any other polysaccharide than gellan resulted in flattening of the beads upon drying. Differential scanning calorimetry confirmed the crystalline form of naproxen. Raman spectra showed that no apparent interactions occurred. In the acidic environment, all the beads revealed the tendency to absorb water. The beads swelled to the greatest extent at pH = 4.5. Naproxen was released from the beads at a varied rate. At pH = 7.4, the most prolonged release was observed for the beads containing carrageenans.

Conclusions

We have proved that blending of gellan with various polysaccharides can change the pH-dependent properties of the beads loaded with naproxen. We believe that the information enclosed in the paper will be of particular importance regarding the development and characteristics of novel oral dosage forms based on natural polymers.

Inhibitory Effect of Aspirin on Cholangiocarcinoma Cells

Aspirin and other non-steroidal anti-inflammatory drugs reduce the risk of cancer due to their anti-proliferative and apoptotic effects, which are the important mechanisms for their anti-tumor activity. Here, the effect of aspirin on human cholangiocarcinoma cells (KKU-214) and the underlying mechanisms of its action were explored. Cell proliferation was measured by sulforhodamine B (SRB) assay, while cell cycle distribution and apoptosis were determined by flow cytometry. Western blotting was used to explore protein expression underlying molecular mechanisms of anti-cancer treatment of aspirin. Aspirin reduced cell proliferation in a dose- and time-dependent manner, and altered the cell cycle phase distribution of KKU-214 cells by increasing the proportion of cells in the G0/G1 phase and reducing the proportion in the S and G2/M phases. Consistent with its effect on the cell cycle, aspirin also reduced the expression of cyclin D1 and cyclin-dependent kinase 4 (Cdk-4), which are important for G0/G1 cell cycle progression. Treatment with aspirin led to increased induction of apoptosis in a dose-dependent manner. Further analysis of the mechanism underlying the effect of this drug showed that aspirin induced the expression of the tumor-suppressor protein p53 while inhibiting the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2). Correspondingly, the activation of caspase-9 and -3 was also increased. These findings suggest that aspirin causes cell cycle arrest and apoptosis, both of which could contribute to its anti-proliferative effect.

Beclin 1 acetylation impairs the anticancer effect of aspirin in colorectal cancer cells

Regular use of aspirin can reduce cancer incidence, recurrence, metastasis and cancer-related mortality. Aspirin suppresses proliferation and induces apoptosis and autophagy in colorectal cancer cells, but the precise mechanism is not clear. In this study, we demonstrated that aspirin induced autophagosome formation in colorectal cancer cells, but autophagic degradation was blocked through aspirin-mediated Beclin 1 acetylation. Blocked autophagic degradation weakened aspirin-induced cell death. Collectively, our findings indicate the dual roles of aspirin on autophagy, and demonstrate a new mechanism by which Beclin 1 acetylation impairs the anticancer effect of aspirin in colorectal cancer cells.

Associations of Calcium and Milk Product Intakes with Incident, Sporadic Colorectal Adenomas

Calcium intake has been consistently, modestly inversely associated with colorectal neoplasms, and supplemental calcium reduced adenoma recurrence in clinical trials. Milk products are the major source of dietary calcium in the United States, but their associations with colorectal neoplasms are unclear. Data pooled from three colonoscopy-based case-control studies of incident, sporadic colorectal adenoma (n = 807 cases, 2,185 controls) were analyzed using multivariable unconditional logistic regression. Residuals from linear regression models of milk with dietary calcium were estimated as the noncalcium, insulin-like growth factor 1-containing component of milk. For total, dietary, and supplemental calcium intakes, the adjusted odds ratios (ORs) comparing the highest to the lowest intake quintiles were 0.94 (95% confidence interval [CI] 0.69-1.30), 0.86 (CI 0.62-1.20), and 0.99 (CI 0.77-1.27), respectively. The corresponding ORs for consumption of total milk products, total milk, nonfat milk, total milk product residuals, and nonfat milk residuals were, respectively, 0.99, 0.90, 0.92, 0.94, and 0.95; all CIs included 1.0. For those who consumed any whole milk relative to those who consumed none, the OR was 1.15 (CI 0.89-1.49). These results are consistent with previous findings of modest inverse associations of calcium intakes with colorectal adenoma, but suggest that milk products may not be associated with adenoma.

Synthesis and Biological Evaluation of Novel Indomethacin Derivatives as Potential Anti-Colon Cancer Agents

The molecular structure of indomethacin was used as a starting scaffold for the synthesis of 20 novel analogs and to study their effects on the proliferation of three human colon cancer cell lines, HCT-116, HT-29, and Caco-2, by MTT assay. The synthesized indomethacin analogs were characterized on the basis of IR, ¹ H NMR, ¹³ C NMR, mass spectral data, and elemental analysis results. Cytotoxicity assay results showed that the indomethacin amide analog 2 was the most potent anticancer agent (IC₅₀  = 0.78, 0.09, and 0.0127 μg/mL) against the three colon cancer cell lines, respectively, being more potent than the standard 5-fluorouracil (IC₅₀  = 1.8, 0.75, and 5.45 μg/mL). Interestingly, the indomethacin oxazin analog 3 and the indomethacin amide analog 8 displayed very potent anticancer activity against the HCT-116 cell line with IC₅₀  = 0.421 and 0.27 μg/mL, respectively, much better than the reference (IC₅₀  = 1.8 μg/mL). Additionally, analogs 3, 4b, 11, 12c, and 13a exhibited excellent antitumor activity against Caco-2 cells, with IC₅₀ ranging from 1.5 to 4.5 μg/mL. Furthermore, analogs 2 and 8 were additionally examined for their effect on the cell cycle of HCT-116 and HT-29 cells, respectively, using flow cytometric analysis. Analog 2 arrested the cell cycle of HT-29 cells at the S phase, while 8 was found to arrest the cell cycle of HCT-116 cells at the G0/G1 phase.

Mast cells positive to tryptase and tumour-associated macrophages correlate with angiogenesis in locally advanced colorectal cancer patients undergone to surgery

OBJECTIVE

The density of mast cells positive to tryptase (MCDPT) and tumor-associated macrophages (TAMs) were evaluated in a series of 87 patients with stage B and C colorectal cancer who had undergone radical surgery.

METHODS

MCDPT, TAMs, microvascular density (MVD), endothelial area (EA) and CD8(+) tumor infiltrating lymphocytes (CD8(+) TILs) were evaluated in tumor tissue samples by immunohistochemistry and image analysis. Each of the above parameters was correlated with the others and with the main clinico-pathological features.

RESULTS

A significant correlation between MCDPT, TAMs, MVD and EA was found by Pearson t-test analysis. With special references to the clinico-pathological features a minimal correlation using univariate analysis was found but it was not retained at multivariate analysis.

CONCLUSIONS

Our data suggest that MCDPT and TAMs are linked in the tumor microenvironment and play a role in CRC angiogenesis in a synergistic manner. The assessment of the combination MCDPT and TAMs could be evaluated as a target of novel anti-angiogenic therapies in colorectal cancer patients.

Cyclin A2 and CDK2 as Novel Targets of Aspirin and Salicylic Acid: A Potential Role in Cancer Prevention

Data emerging from the past 10 years have consolidated the rationale for investigating the use of aspirin as a chemopreventive agent; however, the mechanisms leading to its anticancer effects are still being elucidated. We hypothesized that aspirin's chemopreventive actions may involve cell-cycle regulation through modulation of the levels or activity of cyclin A2/cyclin-dependent kinase-2 (CDK2). In this study, HT-29 and other diverse panel of cancer cells were used to demonstrate that both aspirin and its primary metabolite, salicylic acid, decreased cyclin A2 (CCNA2) and CDK2 protein and mRNA levels. The downregulatory effect of either drugs on cyclin A2 levels was prevented by pretreatment with lactacystin, an inhibitor of proteasomes, suggesting the involvement of 26S proteasomes. In-vitro kinase assays showed that lysates from cells treated with salicylic acid had lower levels of CDK2 activity. Importantly, three independent experiments revealed that salicylic acid directly binds to CDK2. First, inclusion of salicylic acid in naïve cell lysates, or in recombinant CDK2 preparations, increased the ability of the anti-CDK2 antibody to immunoprecipitate CDK2, suggesting that salicylic acid may directly bind and alter its conformation. Second, in 8-anilino-1-naphthalene-sulfonate (ANS)-CDK2 fluorescence assays, preincubation of CDK2 with salicylic acid dose-dependently quenched the fluorescence due to ANS. Third, computational analysis using molecular docking studies identified Asp145 and Lys33 as the potential sites of salicylic acid interactions with CDK2. These results demonstrate that aspirin and salicylic acid downregulate cyclin A2/CDK2 proteins in multiple cancer cell lines, suggesting a novel target and mechanism of action in chemoprevention.

IMPLICATIONS

Biochemical and structural studies indicate that the antiproliferative actions of aspirin are mediated through cyclin A2/CDK2.

Aspirin and salicylic acid decrease c-Myc expression in cancer cells: a potential role in chemoprevention

Epidemiological studies have demonstrated a significant correlation between regular aspirin use and reduced colon cancer incidence and mortality; however, the pathways by which it exerts its anti-cancer effects are still not fully explored. We hypothesized that aspirin's anti-cancer effect may occur through downregulation of c-Myc gene expression. Here, we demonstrate that aspirin and its primary metabolite, salicylic acid, decrease the c-Myc protein levels in human HCT-116 colon and in few other cancer cell lines. In total cell lysates, both drugs decreased the levels of c-Myc in a concentration-dependent fashion. Greater inhibition was observed in the nucleus than the cytoplasm, and immunofluorescence studies confirmed these observations. Pretreatment of cells with lactacystin, a proteasome inhibitor, partially prevented the downregulatory effect of both aspirin and salicylic acid, suggesting that 26S proteasomal pathway is involved. Both drugs failed to decrease exogenously expressed DDK-tagged c-Myc protein levels; however, under the same conditions, the endogenous c-Myc protein levels were downregulated. Northern blot analysis showed that both drugs caused a decrease in c-Myc mRNA levels in a concentration-dependent fashion. High-performance liquid chromatography (HPLC) analysis showed that aspirin taken up by cells was rapidly metabolized to salicylic acid, suggesting that aspirin's inhibitory effect on c-Myc may occur through formation of salicylic acid. Our result suggests that salicylic acid regulates c-Myc level at both transcriptional and post-transcription levels. Inhibition of c-Myc may represent an important pathway by which aspirin exerts its anti-cancer effect and decrease the occurrence of cancer in epithelial tissues.

NSAIDs and Colorectal Cancer Control: Promise and Challenges

The chemoprevention of colorectal cancer (CRC) is a realistic option given the low acceptance and cost of screening colonoscopy. NSAIDs, currently not recommended for CRC prevention, are the most promising agents. Here, we review relevant work and assess the chemopreventive potential of NSAIDs. The chemopreventive efficacy of NSAIDs is established by epidemiological and interventional studies as well as analyses of cardiovascular-prevention randomized clinical trials. The modest chemopreventive efficacy of NSAIDs is compounded by their significant toxicity that can be cumulative. Efforts to overcome these limitations include the use of drug combinations; the emphasis on the early stages of colon carcinogenesis such as aberrant crypt foci, which may require shorter periods of drug administration; and the development of several families of chemically modified NSAIDs such as derivatives of sulindac, nitro-NSAIDs and phospho-NSAIDs, with some of them appearing to have higher safety and efficacy than conventional NSAIDs and thus to be better candidate agents. The successful development of NSAIDs as chemopreventive agents will likely require a combination of the following: identification of subjects at high risk and/or those most likely to benefit from chemoprevention; optimization of the timing, dose and duration of administration of the chemopreventive agent; novel NSAID derivatives and/or combinations of agents; and agents that may prevent other diseases in addition to CRC. Ultimately, the clinical implementation of NSAIDs for the prevention of CRC will depend on a strategy that drastically shifts the currently unacceptable risk/benefit ratio in favor of chemoprevention.

The evolving role of nonsteroidal anti-inflammatory drugs in colon cancer prevention: a cause for optimism

Colorectal cancer (CRC) is a serious yet preventable disease. The low acceptance and cost of colonoscopy as a screening method or CRC make chemoprevention an important option. Nonsteroidal anti-inflammatory drugs (NSAIDs), not currently recommended for CRC prevention, have the potential to evolve into the agents of choice for this indication. Here, we discuss the promise and challenge of NSAIDs for this chemopreventive application.Multiple epidemiologic studies, randomized clinical trials (RCTs) of sporadic colorectal polyp recurrence, RCTs in patients with hereditary colorectal cancer syndromes, and pooled analyses of cardiovascular-prevention RCTs linked to cancer outcomes have firmly established the ability of conventional NSAIDs to prevent CRC. NSAIDs, however, are seriously limited by their toxicity,which can become cumulative with their long-term administration for chemoprevention, whereas drug interactions in vulnerable elderly patients compound their safety. Newer, chemically modified NSAIDs offer the hope of enhanced efficacy and safety.Recent work also indicates that targeting earlier stages of colorectal carcinogenesis, such as the lower complexity aberrant crypt foci, is a promising approach that may only require relatively short use of chemopreventive agents. Drug combination approaches exemplified by sulindac plus difluoromethylornithine appear very efficacious. Identification of those at risk or most likely to benefit from a given intervention using predictive biomarkers may usher in personalized chemoprevention. Agents that offer simultaneous chemoprevention of diseases in addition to CRC, e.g., cardiovascular and/or neurodegenerative diseases,may have a much greater potential for a broad clinical application.

Effect of α-tocopheryl succinate on the molecular damage induced by indomethacin in C6 glioma cells

Indomethacin is a member of the non-steroidal anti-inflammatory drug (NSAID) class, which has great potential for use in the treatment of glioma. However, it induces the generation of reactive oxygen species (ROS) and causes molecular damage while inducing its effects. Vitamin E is widely used in the complementary therapy of cancers. The main goal of the present study was to investigate the effects of α-tocopheryl succinate (α-TOS) against the oxidative damage induced by indomethacin in C6 glioma cells. Cells were treated with 10 μM α-TOS alone or in combination with 200 μM indomethacin for two days. The intracellular ROS level, molecular damage as revealed by lipid peroxidation and protein carbonyl formation, and the COX activity in C6 glioma cells were measured. Treatment of the cells with α-TOS and indomethacin, alone or in combination, caused the levels of ROS generation and protein damage to increase, but protected against lipid peroxidation and reduced COX activity.

Aspirin delimits platelet life span by proteasomal inhibition

Aspirin is widely used in clinical settings as an anti-inflammatory and anti-platelet drug due its inhibitory effect on cyclooxygenase activity. Although the drug has long been considered to be an effective and safe therapeutic regime against inflammatory and cardiovascular disorders, consequences of its cyclooxygenase-independent attributes on platelets, the key players in thrombogenesis, beg serious investigation. In this report we explored the effect of aspirin on platelet lifespan in murine model and its possible cytotoxicity against human platelets in vitro. Aspirin administration in mice led to significant reduction in half-life of circulating platelets, indicative of enhanced rate of platelet clearance. Aspirin-treated human platelets were found to be phagocytosed more efficiently by macrophages, associated with attenuation in platelet proteasomal activity and upregulation of conformationally active Bax, which were consistent with enhanced platelet apoptosis. Although the dosage of aspirin administered in mice was higher than the therapeutic regimen against cardiovascular events, it is comparable with the recommended anti-inflammatory prescription. Thus, above observations provide cautionary framework to critically re-evaluate prophylactic and therapeutic dosage regime of aspirin in systemic inflammatory as well as cardiovascular ailments.

Molecular targets of aspirin and cancer prevention

Salicylates from plant sources have been used for centuries by different cultures to treat a variety of ailments such as inflammation, fever and pain. A chemical derivative of salicylic acid, aspirin, was synthesised and mass produced by the end of the 19th century and is one of the most widely used drugs in the world. Its cardioprotective properties are well established; however, recent evidence shows that it can also act as a chemopreventive agent. Its antithrombotic and anti-inflammatory actions occur through the inhibition of cyclooxygenases. The precise mechanisms leading to its anticancer effects are not clearly established, although multiple mechanisms affecting enzyme activity, transcription factors, cellular signalling and mitochondrial functions have been proposed. This review presents a brief account of the major COX-dependent and independent pathways described in connection with aspirin's anticancer effects. Aspirin's unique ability to acetylate biomolecules besides COX has not been thoroughly investigated nor have all the targets of its primary metabolite, salicylic acid been identified. Recent reports on the ability of aspirin to acetylate multiple cellular proteins warrant a comprehensive study to investigate the role of this posttranslational modification in its anticancer effects. In this review, we also raise the intriguing possibility that aspirin may interact and acetylate cellular molecules such as RNA, and metabolites such as CoA, leading to a change in their function. Research in this area will provide a greater understanding of the mechanisms of action of this drug.

Protective role of aspirin, vitamin C, and zinc and their effects on zinc status in the DMH-induced colon carcinoma model

Chemoprotection refers to the use of specific natural or synthetic chemical agents to suppress or prevent the progression to cancer. The purpose of this study is to assess the protective effect of aspirin, vitamin C or zinc in a dimethyl hydrazine (DMH) colon carcinoma model in rats and to investigate the effect of these supplements on changes associated with colonic zinc status. Rats were randomly divided into three groups, group 1 (aspirin), group 2 (vitamin C) and group 3 (zinc), each being subdivided into two groups and given subcutaneous injection of DMH (30 mg/kg body wt) twice a week for 3 months and sacrificed at 4 months (A-precancer model) and 6 months (B-cancer model). Groups 1, 2, 3 were simultaneously given aspirin, vitamin C, or zinc supplement respectively from the beginning till the end of the study. It was observed that 87.5% of rats co-treated with aspirin or vitamin C showed normal colonic histology, along with a significant decrease in colonic tissue zinc at both time points. Rats co-treated with zinc showed 100% reduction in tumor incidence with no significant change in colonic tissue zinc. Plasma zinc, colonic CuZnSOD (copper-zinc superoxide dismutase) and alkaline phosphatase activity showed no significant changes in all 3 cotreated groups. These results suggest that aspirin, vitamin C or zinc given separately, exert a chemoprotective effect against chemically induced DMH colonic preneoplastic progression and colonic carcinogenesis in rats. The inhibitory effects are associated with maintaining the colonic tissue zinc levels and zinc enzymes at near normal without significant changes.

Molecular therapy of colorectal cancer: progress and future directions

Colorectal cancer (CRC) remains one of the most common types of cancer and leading causes of cancer death worldwide. Although the introduction of cytotoxic drugs such as oxaliplatin, irinotecan and fluorouracil has improved the treatment of advanced CRC, the individual response to chemoradiotherapy varies tremendously from one patient to another. However, recent progress in CRC molecular therapies may provide new insight into the treatment of this disease. Currently, components of the EGFR, VEGF, Wnt and NF-kB pathways are the most important targets for CRC therapy. This review chronicles the development of molecular CRC therapies over the past few decades. We also provide an update on the current progress of research concerning the molecular pathways leading to CRC and discuss the possible implications for CRC therapy.

Role of chemoprophylaxis with either NSAIDs or statins in patients with Barrett's esophagus

The incidence of esophageal adenocarcinoma, a poor prognosis neoplasia, has risen dramatically in recent decades. Barrett's esophagus represents the best-known risk factor for esophageal adenocarcinoma development. Non-steroidal anti-inflammatory drugs through cyclooxygenase-2 inhibition and prostaglandin metabolism regulation could control cell proliferation, increase cell apoptosis and regulate the expression of growth and angiogenic factors. Statins can achieve equivalent effects through prenylation and subsequently control of cellular signaling cascades. At present, epidemiological studies are small and underpowered. Their data could not justify either medication as a chemo-preventive agent. Population based studies have shown a 43% reduction of the odds of developing an esophageal adenocarcinoma, leaving out or stating a 25% reduction in patients consuming non-aspirin nonsteroidal anti-inflammatory drugs and a 50% reduction in those patients consuming aspirin. They have also stated a 19% reduction of esophageal cancer incidence when statins have been used. Observational studies have shown that non-steroidal anti-inflammatory drugs could reduce the adenocarcinoma incidence in patients with Barrett's esophagus by 41%, while statins could reduce the risk by 43%. The cancer preventive effect has been enhanced in those patients taking a combination of non-steroidal anti-inflammatory drugs and statins (a 74% decrease). Observational data are equivocal concerning the efficacy of non-steroidal anti-inflammatory drug subclasses. Non-steroidal anti-inflammatory drugs clearly have substantial potential for toxicity, while statins are rather safe drugs. In conclusion, both non-steroidal anti-inflammatory drugs and statins are promising chemopreventive agents and deserve further exploration with interventional studies. In the meanwhile, their use is justified only in patients with cardiovascular disease.

Ibuprofen enhances the anticancer activity of cisplatin in lung cancer cells by inhibiting the heat shock protein 70

Hsp70 is often overexpressed in cancer cells, and the selective cellular survival advantage that it confers may contribute to the process of tumour formation. Thus, the pharmacological manipulation of Hsp70 levels in cancer cells may be an effective means of preventing the progression of tumours. We found that the downregulation of Hsp70 by ibuprofen in vitro enhances the antitumoural activity of cisplatin in lung cancer. Ibuprofen prominently suppressed the expression of Hsp70 in A549 cells derived from lung adenocarcinoma and sensitized them to cisplatin in association with an increase in the mitochondrial apoptotic cascade, whereas ibuprofen alone did not induce cell death. The cisplatin-dependent events occurring up- and downstream of mitochondrial disruption were accelerated by treatment with ibuprofen. The increase in cisplatin-induced apoptosis caused by the depletion of Hsp70 by RNA interference is evidence that the increased apoptosis by ibuprofen is mediated by its effect on Hsp70. Our observations indicate that the suppression of Hsp70 by ibuprofen mediates the sensitivity to cisplatin by enhancing apoptosis at several stages of the mitochondrial cascade. Ibuprofen, therefore, is a potential therapeutic agent that might allow lowering the doses of cisplatin and limiting the many challenge associated with its toxicity and development of drug resistance.

Ibuprofen inhibits colitis-induced overexpression of tumor-related Rac1b

The serrated pathway to colorectal tumor formation involves oncogenic mutations in the BRAF gene, which are sufficient for initiation of hyperplastic growth but not for tumor progression. A previous analysis of colorectal tumors revealed that overexpression of splice variant Rac1b occurs in around 80% of tumors with mutant BRAF and both events proved to cooperate in tumor cell survival. Here, we provide evidence for increased expression of Rac1b in patients with inflamed human colonic mucosa as well as following experimentally induced colitis in mice. The increase of Rac1b in the mouse model was specifically prevented by the nonsteroidal anti-inflammatory drug ibuprofen, which also inhibited Rac1b expression in cultured HT29 colorectal tumor cells through a cyclooxygenase inhibition.independent mechanism. Accordingly, the presence of ibuprofen led to a reduction of HT29 cell survival in vitro and inhibited Rac1b-dependent tumor growth of HT29 xenografts. Together, our results suggest that stromal cues, namely, inflammation, can trigger changes in Rac1b expression in the colon and identify ibuprofen as a highly specific and efficient inhibitor of Rac1b overexpression in colorectal tumors. Our data suggest that the use of ibuprofen may be beneficial in the treatment of patients with serrated colorectal tumors or with inflammatory colon syndromes.

Nonsteroidal anti-inflammatory drug sulindac sulfide suppresses structural protein Nesprin-2 expression in colorectal cancer cells

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are well known for treating inflammatory disease and have been reported to have anti-tumorigenic effects. Their mechanisms are not fully understood, but both cyclooxygenase (COX) dependent and independent pathways are involved. Our goal was to shed further light on COX-independent activity.

METHODS

Human colorectal cancer cells were observed under differential interference contrast microscopy (DICM), fluorescent microscopy, and micro-impedance measurement. Microarray analysis was performed using HCT-116 cells treated with sulindac sulfide (SS). PCR and Western blots were performed to confirm the microarray data and immunohistochemistry was performed to screen for Nesprin-2 expression. Micro-impedance was repeating including Nesprin-2 knock-down by siRNA.

RESULTS

HCT-116 cells treated with SS showed dramatic morphological changes under DICM and fluorescent microscopy, as well as weakened cellular adhesion as measured by micro-impedance. Nesprin-2 was selected from two independent microarrays, based on its novelty in relation to cancer and its role in cell organization. SS diminished Nesprin-2 mRNA expression as assessed by reverse transcriptase and real time PCR. Various other NSAIDs were also tested and demonstrated that inhibition of Nesprin-2 mRNA was not unique to SS. Additionally, immunohistochemistry showed higher levels of Nesprin-2 in many tumors in comparison with normal tissues. Further micro-impedance experiments on cells with reduced Nesprin-2 expression showed a proportional loss of cellular adhesion.

CONCLUSIONS

Nesprin-2 is down-regulated by NSAIDs and highly expressed in many cancers.

GENERAL SIGNIFICANCE

Our data suggest that Nesprin-2 may be a potential novel oncogene in human cancer cells and NSAIDs could decrease its expression.

COX-2 expression in canine anal sac adenocarcinomas and in non-neoplastic canine anal sacs

Anal sac adenocarcinoma (ASAC) is a clinically significant canine neoplasm characterized by early lymphatic invasion. Up-regulation of cyclooxygenase isoform 2 (COX-2) has been confirmed in several animal and human neoplastic tissues. The aim of the current study was primarily to evaluate COX-2 expression in canine ASAC and compare it to COX-2 expression in non-neoplastic canine anal sac tissue using immunohistochemistry with scoring for percentage positivity and intensity. Twenty-five ASAC samples and 22 normal anal sacs were available for evaluation. All canine ASAC samples and the normal anal sac tissues stained positively for COX-2. However, while normal anal sac tissue showed strong staining of the ductal epithelial cells, ASAC samples showed staining of the neoplastic glandular epithelial cells, with varying percentage positivity and intensity between ASAC samples. COX-2 immunoreactivity of ASAC samples was of low intensity in 52% and high in 12% of the cases; the remaining samples were of intermediate intensity. Seventy-six per cent of the ASAC had over 50% of the neoplastic glandular cells staining positive. These results confirm that COX-2 is expressed in the neoplastic glandular epithelial cells in canine ASAC and suggest a potential role for COX-2 inhibitors in the management of ASAC. Furthermore, the results indicate that COX-2 is expressed in ductal epithelial cells of the normal anal sac.

Simvastatin enhances human osteoblast proliferation involved in mitochondrial energy generation

Simvastatin has been shown to stimulate osteogenic cell differentiation. Our previous study showed osteoblasts on trabecular surface are increased by simvastatin treatment in animal study. However, whether simvastatin stimulates osteoblast proliferation and by what molecular mechanism have not been adequately investigated. Because the mitochondrial function is crucial for cell survival and proliferation, we hypothesize that simvastatin may promote human osteoblast (hOBs) proliferation and it may be related to mitochondrial function. Our results showed that simvastatin significantly enhanced proliferation and increased both mRNA and protein levels of cyclin D2, Bcl-2 and the ratio of Bcl-2 to Bax (Bcl-2/Bax). Furthermore, simvastatin increased mitochondrial activity and ATP content of hOBs. Most importantly, treatment with ATP synthase blocker, oligomycin, significantly decreased both simvastatin-stimulated ATP content and cell proliferation, and completely reversed the simvastatin-induced up-regulation of cyclin D2 and Bcl-2 expression in hOBs. On the other hand, rotenone, the complex I blocker, also partially blocked simvastatin-stimulated ATP content and cell proliferation, but the blocker did not suppress the effect of simvastatin on cyclin D2 and Bcl-2 expression. These results indicate that the up-regulation of cyclin D2 and Bcl-2/Bax by simvastatin depends on the intact function of ATP synthase in the mitochondria of hOBs. It suggests that simvastatin may promote hOB proliferation, at least partly, via up-regulating mitochondrial function and subsequently cyclin D2 and Bcl-2/Bax expression. The findings provide new information for the basic medical science in bone physiology and for new therapy strategy of simvastatin on bone formation in future.

Comparative in vitro metabolism of phospho-tyrosol-indomethacin by mice, rats and humans

Phospho-tyrosol-indomethacin (PTI; MPI 621), a novel anti-cancer agent, is more potent and safer than conventional indomethacin. Here, we show that PTI was extensively metabolized in vitro and in vivo. PTI was rapidly hydrolyzed by carboxylesterases to generate indomethacin as its major metabolite in the liver microsomes and rats. PTI additionally undergoes cytochromes P450 (CYP)-mediated hydroxylation at its tyrosol moiety and O-demethylation at its indomethacin moiety. Of the five major human CYPs, CYP3A4 and CYP2D6 catalyze the hydroxylation and O-demethylation reactions of PTI, respectively; whereas CYP1A2, 2C9 and 2C19 are inactive towards PTI. In contrast to PTI, indomethacin is primarily O-demethylated by CYP2C9, which prefers acidic substrates. The hydrolyzed and O-demethylated metabolites of PTI are further glucuronidated and sulfated, facilitating drug elimination and detoxification. We observed substantial inter-species differences in the metabolic rates of PTI. Among the liver microsomes from various species, PTI was the most rapidly hydrolyzed, hydroxylated and O-demethylated in mouse, human and rat liver microsomes, respectively. These results reflect the differential expression patterns of carboxylesterase and CYP isoforms among these species. Of the human microsomes from various tissues, PTI underwent more rapid carboxylesterase- and CYP-catalyzed reactions in liver and intestine microsomes than in kidney and lung microsomes. Together, our results establish the metabolic pathways of PTI, reveal significant inter-species differences in its metabolism, and provide insights into the underlying biochemical mechanisms.

Implication of eIF2α kinase GCN2 in induction of apoptosis and endoplasmic reticulum stress-responsive genes by sodium salicylate

OBJECTIVES

Sodium salicylate (NaSal) can disturb cell viability by affecting the activity of multiple cellular molecules. In this work, we investigated the involvement of stress-responsive kinase GCN2 in regulating cell death and expression of stress genes in mouse embryonic fibroblasts (MEFs) upon exposure to NaSal.

METHODS

Cell viability was assayed using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) method, and apoptosis was evaluated by annexin V and propidium iodide staining. A polymerase chain reaction (PCR) array approach was used to analyse differential expression of a panel of 84 endoplasmic reticulum (ER) stress-associated genes. Gene reporter assays were carried out to determine activity of ER stress element (ERSE), and the protein levels of activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) were determined by western blot.

KEY FINDINGS

NaSal treatment resulted in reduction of cellular viability and induction of apoptosis in wild-type but not Gcn2(-/-) cells. Many genes with important functions in protein synthesis/degradation, transcriptional regulation and apoptosis were induced by NaSal and most of these were dependent on GCN2. The activation of ERSE within Ddit3 and the production of CHOP and ATF6 induced by NaSal required GCN2.

CONCLUSIONS

Our data provide evidence for the involvement of GCN2 in apoptosis and gene expression triggered by NaSal, and contributes to the understanding of molecular events occurring in NaSal-treated cells.

Aspirin inhibits mTOR signaling, activates AMP-activated protein kinase, and induces autophagy in colorectal cancer cells

BACKGROUND & AIMS

Aspirin reduces the incidence of and mortality from colorectal cancer (CRC) by unknown mechanisms. Cancer cells have defects in signaling via the mechanistic target of rapamycin (mTOR), which regulates proliferation. We investigated whether aspirin affects adenosine monophosphate-activated protein kinase (AMPK) and mTOR signaling in CRC cells.

METHODS

The effects of aspirin on mTOR signaling, the ribosomal protein S6, S6 kinase 1 (S6K1), and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) were examined in CRC cells by immunoblotting. Phosphorylation of AMPK was measured; the effects of loss of AMPKα on the aspirin-induced effects of mTOR were determined using small interfering RNA (siRNA) in CRC cells and in AMPK(α1/α2-/-) mouse embryonic fibroblasts. LC3 and ULK1 were used as markers of autophagy. We analyzed rectal mucosa samples from patients given 600 mg aspirin, once daily for 1 week.

RESULTS

Aspirin reduced mTOR signaling in CRC cells by inhibiting the mTOR effectors S6K1 and 4E-BP1. Aspirin changed nucleotide ratios and activated AMPK in CRC cells. mTOR was still inhibited by aspirin in CRC cells after siRNA knockdown of AMPKα, indicating AMPK-dependent and AMPK-independent mechanisms of aspirin-induced inhibition of mTOR. Aspirin induced autophagy, a feature of mTOR inhibition. Aspirin and metformin (an activator of AMPK) increased inhibition of mTOR and Akt, as well as autophagy in CRC cells. Rectal mucosal samples from patients given aspirin had reduced phosphorylation of S6K1 and S6.

CONCLUSIONS

Aspirin is an inhibitor of mTOR and an activator of AMPK, targeting regulators of intracellular energy homeostasis and metabolism. These could contribute to its protective effects against development of CRC.

NONSTEROIDAL ANTI-INFLAMMATORY DRUGS ARREST CELL CYCLE IN G0/G1PHASE AND INDUCE CELL DEATH IN OSTEOBLAST-ENRICHED CULTURES

Nonsteroidal anti-inflammatory drugs have been widely prescribed for orthopaedic patients to relieve pain and chronic inflammation. However, it has been demonstrated that NSAIDs suppress bone repair and remodeling in vivo. We have reported that ketorolac inhibits bone repair in vivo and its critical effective timing is at the early stage of endochondral ossification. Our previous results showed that ketorolac and indomethacin inhibit osteoblast proliferation in vitro, suggesting that this effect may be one of the mechanisms contributing to the suppressive effect of NSAIDs on bone remodeling. Cell proliferation and death of osteoblasts should be well regulated through some relative apoptotic and mitotic factors during normal bone remodeling process. Accordingly, we proposed that the induction of osteoblastic cell death of NSAIDs might be one of the mechanisms involving their suppressive effect on bone remodeling in vivo. In this study, we investigated whether NSAIDs arrest osteoblastic cell cycle and/or induce cell death. Whether the mechanism was mediated through prostaglandin (PG) pathway. We tested the effects of ketorolac, indomethacin, diclofenac, piroxicam on cell cycle kinetics, cytotoxicity, and cell death pattern in osteoblast-enriched cultures derived from fetal rat calvaria. Our results showed that ketorolac and indomethacin arrested cell cycle at G0/G1phase. All the 4 NSAIDs had cytotoxic effects and these effects were concentration dependent. The sequence of the cytotoxic effects of these four NSAIDs at 10-4M were indomethacin > diclofenac > ketorolac > piroxicam. Both PGE1and PGE2(10-10-10-8M) also significantly elevated the LDH leakage of osteoblasts, while PGF2αhad no significant effect. These results revealed that the cytotoxic effects of NSAIDs on osteoblasts might not be through inhibiting prostaglandin synthesis. They may be through PG-independent pathways. The results from flow cytometry followed by AnnexinV-FITC and propidium iodide double staining showed that 24 hours treatment of all the 4 NSAIDs (10-6and 10-4M) significantly induced both apoptosis (p<0.01) and necrosis (p<0.01, or p<0.05) in osteoblast cultures. These effects of NSAIDs on cell cycle arrest and cell death induction in osteoblasts may be one of the important mechanisms contributing to their suppressive effect on bone repair and bone remodeling in vivo.

In the Huh7 Hepatoma Cells Diclofenac and Indomethacin Activate Differently the Unfolded Protein Response and Induce ER Stress Apoptosis

Non-steroidal anti-inflammatory drugs (NSAIDs) are cyclooxygenases (COXs) inhibitors frequently used in the treatment of acute and chronic inflammation. Side effects of NSAIDs are often due to their ability to induce apoptosis. Located at the Endoplasmic Reticulum membranes a tripartite signalling pathway, collectively known as the Unfolded Protein Response (UPR), decides survival or death of cells exposed to cytotoxic agents. To shed light on the molecular events responsible for the cytotoxicity of NSAIDs, we analysed the ability of diclofenac and indomethacin to activate the UPR in the human hepatoma cell line Huh7. We report that both NSAIDs can induce differently the single arms of the UPR. We show that indomethacin turns on the PERK and, only in part, the ATF6 and IRE1 pathways. Instead, diclofenac reduces the expression of ATF6 and does not stimulate the IRE1 endonuclease, which drives the expression of the prosurvival factor XBP1. Diclofenac, as well as indomethacin, is able to activate efficiently only the PERK pathway of the UPR, which induces the expression of the proapoptotic GADD153/CHOP protein. Our results highlight the importance of the UPR in evaluating the potential of drugs to induce apoptosis.