Evidence for colorectal cancer cell specificity of aspirin effects on NF kappa B signalling and apoptosis

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.

Chinese herbal medicine for the treatment of cardiovascular diseases ─ targeting cardiac ion channels

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality, imposing an increasing global health burden. Cardiac ion channels (voltage-gated Na_V, Ca_V, K_Vs, and others) synergistically shape the cardiac action potential (AP) and control the heartbeat. Dysfunction of these channels, due to genetic mutations, transcriptional or post-translational modifications, may disturb the AP and lead to arrhythmia, a major risk for CVD patients. Although there are five classes of anti-arrhythmic drugs available, they can have varying levels of efficacies and side effects on patients, possibly due to the complex pathogenesis of arrhythmias. As an alternative treatment option, Chinese herbal remedies have shown promise in regulating cardiac ion channels and providing anti-arrhythmic effects. In this review, we first discuss the role of cardiac ion channels in maintaining normal heart function and the pathogenesis of CVD, then summarize the classification of Chinese herbal compounds, and elaborate detailed mechanisms of their efficacy in regulating cardiac ion channels and in alleviating arrhythmia and CVD. We also address current limitations and opportunities for developing new anti-CVD drugs based on Chinese herbal medicines.

Aspirin increases chemosensitivity of colorectal cancer cells and inhibits the expression of toll-like receptor 4

BACKGROUND

Chemotherapy resistance is an important bottleneck affecting the efficacy of chemotherapy in colon cancer. Therefore, improving the chemotherapy sensitivity of colorectal cancer cells is of great significance for improving the prognosis of patients with colon cancer.

METHODS

CCK-8 assay was employed to examine the cell viability of colorectal cancer cell lines. Realtime-PCR and western blot were used to explore toll-like receptor 4 (TLR4) expression in colorectal cancer cell lines. The functions of TLR4 in the stemness of the colorectal cancer cell lines were analyzed by infecting cells with lentivirus containing TLR4 siRNA.

RESULTS

We found that aspirin could effectively enhance the chemosensitivity of CT26 and HCT116 colorectal cancer cell lines. Aspirin can also inhibit the stemness of colorectal cancer cell including inhibiting the number of clone formation and reducing the volume and number of cell spheres and inducing the down-regulation of stemness-related genes. Besides that, aspirin also lead to down-regulation of TLR4 expression in colorectal cancer cells. The TLR4 positive colorectal cancer cells demonstrated a higher chemotherapy resistance potential than TLR4 negative colorectal cancer cells. In addition, the stemness of TLR4 positive colorectal cancer cells is stronger than TLR4 negative colorectal cancer cells.

CONCLUSION

The results of our study indicate that aspirin increases chemosensitivity of colorectal cancer cells and inhibits the expression of toll-like receptor 4.

The Targeting of Nuclear Factor Kappa B by Drugs Adopted for the Prevention and Treatment of Preeclampsia

Preeclampsia (PE) is characterised by high levels and activity of the transcription factor Nuclear Factor kappa B (NFĸB) in the maternal blood and placental cells. This factor is responsible for the regulation of over 400 genes known to influence processes related to inflammation, apoptosis and angiogenesis, and cellular responses to oxidative stress and hypoxia. Although high NFĸB activity induces hypoxia and inflammation, which are beneficial for the process of implantation, NFĸB level should be reduced in the later stages of physiological pregnancy to favour maternal immunosuppression and maintain gestation. It is believed that the downregulation of NFĸB activity by pharmacotherapy might be a promising way to treat preeclampsia. Interestingly, many of the drugs adopted for the prevention and treatment of preeclampsia have been found to regulate NFĸB activity. Despite this, further innovation is urgently needed to ensure treatment safety and efficacy. The present article summarizes the current state of knowledge about the drugs recommended by cardiology, obstetrics, and gynaecology societies for the prevention and treatment of preeclampsia with regard to their impact on the cellular regulation of NFĸB pathways.

AMPK activators for the prevention and treatment of neurodegenerative diseases

INTRODUCTION

As the global population ages at an unprecedented rate, the burden of neurodegenerative diseases is expected to grow. Given the profound impact illness like dementia exert on individuals and society writ large, researchers, physicians, and scientific organizations have called for increased investigation into their treatment and prevention. Both metformin and aspirin have been associated with improved cognitive outcomes. These agents are related in their ability to stimulate AMP kinase (AMPK). Momordica charantia, another AMPK activator, is a component of traditional medicines and a novel agent for the treatment of cancer. It is also being evaluated as a nootropic agent.

AREAS COVERED

This article is a comprehensive review which examines the role of AMPK activation in neuroprotection and the role that AMPK activators may have in the management of dementia and cognitive impairment. It evaluates the interaction of metformin, aspirin, and Momordica charantia, with AMPK, and reviews the literature characterizing these agents' impact on neurodegeneration.

EXPERT OPINION

We suggest that AMPK activators should be considered for the treatment and prevention of neurodegenerative diseases. We identify multiple areas of future investigation which may have a profound impact on patients worldwide.

Aspirin inhibits prostaglandins to prevents colon tumor formation via down-regulating Wnt production

According to numerous epidemiological studies, aspirin is a non-steroidal anti-inflammatory drug (NSAID) that reduces the occurrence and mortality of colorectal cancer (CRC). However, the underlying mechanisms are not well identified. In an effort to fill these gaps, we administered aspirin on mice one day before induction in an azoxymethane (AOM)/dextran sulfate sodium (DSS) induced CRC model. In this study, we assessed the effects of aspirin on tumorigenesis and tumor cell proliferation. Multi-layer analyses were carried out to identify changes in cytokines, metabolites, level of gene expressions, and proteins associated with tumorigenesis and aspirin treatment. The results showed that aspirin-treated mice developed fewer colon tumors in response to AOM/DSS, and aspirin can actively block cyclooxygenase (COX) metabolism and reduce levels of pro-inflammatory cytokines. In addition, the transcriptomic and proteomic analyses both indicated that aspirin has an inhibitory effect on the Wnt pathway. The in vitro results further indicated that aspirin inhibits WNT6 production, possibly by suppressing its transcription factor NR4A2, which in turn is regulated by prostaglandin E2, thereby ultimately inhibiting the Wnt pathway. These findings improve our understanding of the mechanisms behind aspirin's chemoprevention effect on CRC.

Aspirin and Statin Use and the Risk of Gallbladder Cancer

Simple Summary

The effects of aspirin on various gastrointestinal cancers have been extensively studied, but the potential protective effect of aspirin and statins on the prevention of gallbladder cancer (GBC) has not been adequately evaluated. The anticancer effect of aspirin has been attributed to direct inhibition of cyclooxygenase (COX)-2. Interestingly, increased expression of COX-2 has been documented in GBC. Hence, we hypothesized that aspirin could potentially have a preventive role in decreasing the risk of GBC. In this study, we demonstrated that the use of aspirin either alone or in combination with statins was associated with a strong reduction in risk of GBC.

Abstract

Aspirin and statin drugs have been associated with reduced risk of several gastrointestinal cancers, but their association with gallbladder cancer (GBC) has not been well established. We evaluated the association of aspirin and statins with the risk of GBC. Patients with GBC managed at Mayo Clinic between 2000 and 2019 were matched 1:2 with a general patient pool by age and sex. Univariable and multivariable logistic regression models were used to assess associations between GBC and aspirin or statin use. The analysis included 795 cases and 1590 controls, with a median age of 67 years. Aspirin or statin use alone or in combination was higher in controls (p < 0.001). Univariate analysis showed that the use of aspirin [odds ratio (OR): 0.11; 95%CI: 0.08–0.15] or statins (OR: 0.29; 95%CI: 0.20–0.40) and their combined use (OR: 0.18; 95%CI: 0.13–0.24) was associated with lower risk of GBC. Multivariable analysis revealed that aspirin (OR: 0.12; 95%CI: 0.09–0.16) and combined statins and aspirin (OR: 0.46; 95%CI: 0.31–0.67) were associated with lower risk of GBC. Aspirin alone or in combination with statins is associated with a strongly reduced risk of GBC. Further prospective studies are needed to confirm these results and to elucidate their mechanisms.

Acetylsalicylic Acid Exerts Potent Antitumor and Antiangiogenic Effects in Cutaneous and Uveal Melanoma Cell Lines

Introduction

Acetylsalicylic acid (ASA) has been investigated for a potential anticancer role in several cancers, such as colorectal, ovarian, and endometrial cancer. Moreover, ASA has been shown to abrogate various processes that contribute to tumor growth and progression.

Objective

The aim of this study was to evaluate the effects of ASA on cutaneous melanoma (CM) and uveal melanoma (UM).

Methods

Human CM and UM cells were treated with 5 mM ASA and assessed for changes in cellular functions. Antiangiogenic effects of ASA were determined using an ELISA-based assay for 10 proangiogenic cytokines, and then validated by Western blot. Finally, proteomic analysis of ASA-treated cells was performed to elucidate the changes that may be responsible for ASA-mediated effects in melanoma cells.

Results

Treatment with ASA significantly inhibited the proliferation, invasion, and migration capabilities, and caused a significant decrease in angiogenin and PIGF secretion in both CM and UM. Mass spectrometry revealed 179 protein changes associated with ASA in the CM and UM cell lines.

Conclusions

These results suggest that ASA may be effective as an adjuvant therapy in metastatic CM and UM. Future studies are needed to determine the regulating targets that are responsible for the antitumor effects of ASA.

Cyclooxygenase activity mediates colorectal cancer cell resistance to the omega-3 polyunsaturated fatty acid eicosapentaenoic acid

Purpose

The naturally-occurring omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) is safe, well-tolerated and inexpensive, making it an attractive anti-cancer intervention. However, EPA has only modest anti-colorectal cancer (CRC) activity, when used alone. Both cyclooxygenase (COX) isoforms metabolise EPA and are over-expressed in CRC cells. We investigated whether COX inhibition increases the sensitivity of CRC cells to growth inhibition by EPA.

Methods

A panel of 18 human and mouse CRC cell lines was used to characterize the differential sensitivity of CRC cells to the growth inhibitory effects of EPA. The effect of CRISPR-Cas9 genetic deletion and pharmacological inhibition of COX-1 and COX-2 on the anti-cancer activity of EPA was determined using in vitro and in vivo models.

Results

Genetic ablation of both COX isoforms increased sensitivity of CT26 mouse CRC cells to growth inhibition by EPA in vitro and in vivo. The non-selective COX inhibitor aspirin and the selective COX-2 inhibitor celecoxib increased sensitivity of several human and mouse CRC cell lines to EPA in vitro. However, in a MC38 mouse CRC cell tumour model, with dosing that mirrored low-dose aspirin use in humans, thereby producing significant platelet COX-1 inhibition, there was ineffective intra-tumoral COX-2 inhibition by aspirin and no effect on EPA sensitivity of MC38 cell tumours.

Conclusion

Cyclooxygenase inhibition by non-steroidal anti-inflammatory drugs represents a therapeutic opportunity to augment the modest anti-CRC activity of EPA. However, intra-tumoral COX inhibition is likely to be critical for this drug-nutrient interaction and careful tissue pharmacodynamic profiling is required in subsequent pre-clinical and human studies.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04157-2) contains supplementary material, which is available to authorized users.

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.

Aspirin suppresses tumor cell-induced angiogenesis and their incongruity

Tumor neovascularization/tumor angiogenesis is a pathophysiological process in which new blood vessels are formed from existing blood vessels in the primary tumors to supply adequate oxygen and nutrition to cancer cells for their proliferation and metastatic growth to the distant organs. Therefore, controlling tumor angiogenesis is an attractive target for cancer therapy. Structural abnormalities of the vasculature (i.e., leakiness due to the abnormal lining of pericytes on the microvessels) are one of the critical features of tumor angiogenesis that sensitizes vascular cells to cytokines and helps circulating tumor cells to metastasize to distant organs. Our goal is to repurpose the drugs that may prevent tumor angiogenesis or normalize the vessels by repairing leakiness via recruiting pericytes or both. In this study, we tested whether aspirin (ASA), which could block primary tumor growth, regulates tumor angiogenesis. We investigated the effects of low (1 mM) and high (2.5 mM) doses of ASA (direct effect), and ASA-treated or untreated triple negative breast cancer (TNBC) cells' conditioned media (indirect effect) on endothelial cell physiology. These include in vitro migration using modified Boyden chamber assay, in vitro capillary-like structure formation on Matrigel, interactions of pericytes-endothelial cells and cell permeability using in vitro endothelial permeability assay. We also examined the effect of ASA on various molecular factors associated with tumor angiogenesis. Finally, we found the outcome of ASA treatment on in vivo tumor angiogenesis. We found that ASA-treatment (direct or indirect) significantly blocks in vitro migration and capillary-like structure formation by endothelial cells. Besides, we found that ASA recruits pericytes from multipotent stem cells and helps in binding with endothelial cells, which is a hallmark of normalization of blood vessels, and decreases in vitro permeability through endothelial cell layer. The antiangiogenic effect of ASA was also documented in vivo assays. Mechanistically, ASA treatment blocks several angiogenic factors that are associated with tumor angiogenesis, and suggesting ASA blocks paracrine-autocrine signaling network between tumor cells and endothelial cells. Collectively, these studies implicate aspirin with proper dose may provide potential therapeutic for breast cancer via blocking as well as normalizing tumor angiogenesis.

Aspirin metabolites 2,3‑DHBA and 2,5‑DHBA inhibit cancer cell growth: Implications in colorectal cancer prevention

Although compelling evidence exists on the ability of aspirin to treat colorectal cancer (CRC), and numerous theories and targets have been proposed, a consensus has not been reached regarding its mechanism of action. In this regard, a relatively unexplored area is the role played by aspirin metabolites 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA) in its chemopreventive actions. In a previous study, we demonstrated that 2,3-DHBA and 2,5-DHBA inhibited CDK1 enzyme activity in vitro. The aim of the present study was to understand the effect of these metabolites on the enzyme activity of all CDKs involved in cell cycle regulation (CDKs 1, 2, 4 and 6) as well as their effect on clonal formation in three different cancer cell lines. Additionally, in silico studies were performed to determine the potential sites of interactions of 2,3-DHBA and 2,5-DHBA with CDKs. We demonstrated that 2,3-DHBA and 2,5-DHBA inhibits CDK-1 enzyme activity beginning at 500 µM, while CDK2 and CDK4 activity was inhibited only at higher concentrations (>750 µM). 2,3-DHBA inhibited CDK6 enzyme activity from 250 µM, while 2,5-DHBA inhibited its activity >750 µM. Colony formation assays showed that 2,5-DHBA was highly effective in inhibiting clonal formation in HCT-116 and HT-29 CRC cell lines (250–500 µM), and in the MDA-MB-231 breast cancer cell line (~100 µM). In contrast 2,3-DHBA was effective only in MDA-MB-231 cells (~500 µM). Both aspirin and salicylic acid failed to inhibit all four CDKs and colony formation. Based on the present results, it is suggested that 2,3-DHBA and 2,5-DHBA may contribute to the chemopreventive properties of aspirin, possibly through the inhibition of CDKs. The present data and the proposed mechanisms should open new areas for future investigations.

Relationship between long-term use of proton pump inhibitors and risk of gastric cancer: A systematic analysis

BACKGROUND AND AIM

This study aims to systematically analyze the effect of long-term therapy with proton pump inhibitors (PPIs) on the risk of gastric cancer.

METHODS

PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), and China biomedical literature database (CBM) were searched for studies before February 2019. We evaluated the quality of the included articles through the Newcastle-Ottawa Scale and gathered relevant data to calculate the pooled odds ratio (OR) through Stata14.0.

RESULTS

Seven relevant articles conformed to the inclusion criteria; 943 070 patients were included. The pooled OR was 2.50; 95% CI (1.74, 3.85); the subgroup analysis results showed that patients who had used PPIs for more than 36 months were most likely to develop gastric cancer, and an increased risk was observed among patients after Helicobacter pylori eradication. Noncardia gastric cancer was more likely to develop.

CONCLUSIONS

Long-term use of PPIs can possibly increase the risk of gastric cancer even among patients after H. pylori eradication; in particular, for noncardia gastric cancer, the risk increases with longer durations of PPI use. Due to the limited number of studies, more high-quality studies are required to be designed.

Effects of low-dose aspirin on clinical outcome and disease progression in patients with gastroenteropancreatic neuroendocrine neoplasm

Objective: The chemopreventive effect of aspirin (ASA) has been observed in the setting of colorectal cancer and other solid neoplasms. Recently, ASA has demonstrated a promising anti-proliferative effect on GEP-NENs in vitro. However, the direct anti-neoplastic impact of ASA on GEP-NEN clinical outcome is yet to be clarified. Materials and methods: All the GEP-NEN patients followed up in three European Centers from January 2005 to September 2016 were retrospectively enrolled. Patients taking ASA in doses of 75-100 mg daily for cardiovascular prevention for at least six months were evaluated. The possible association between ASA and disease grading, staging, primary site, OS and PFS were evaluated. Results: Two hundred fifty one patients were included (117 males, median age 63 years). Of these, 64 patients were prescribed with ASA. No clear impact on OS or PFS was observed in GEP-NEN patients taking ASA compared to those not taking it. ASA intake was related with the patients' older age. At Cox multivariate analysis, stage IV and Ki-67 resulted independent predictors for OS and PFS. In the setting of intestinal NENs, a suggestive, but not statistically significant, protective role of ASA on PFS was observed [HR 0.41 (95% CI: 0.13-1.29)]. Conclusions: Despite ASA showed promising anti-proliferative effects in vitro and a chemopreventive action in NENs has been reported, a clear impact of ASA on survival in NENs has not emerged from the present study. However, in the subgroup of patients with small-intestine NENs, ASA showed a trend toward a protective role.

Insights into the Relationship between Nucleolar Stress and the NF-κB Pathway

The nuclear organelle the nucleolus and the transcription factor nuclear factor of κ-light-chain-enhancer of activated B cells (NF-κB) are both central to the control of cellular homeostasis, dysregulated in common diseases and implicated in the ageing process. Until recently, it was believed that they acted independently to regulate homeostasis in health and disease. However, there is an emerging body of evidence suggesting that nucleoli and NF-κB signalling converge at multiple levels. Here we will review current understanding of this crosstalk. We will discuss activation of the NF-κB pathway by nucleolar stress and induction of apoptosis by nucleolar sequestration of NF-κB/RelA. We will also discuss the role of TIF-IA, COMMD1, and nucleophosmin, which are key players in this crosstalk, and the therapeutic relevance, particularly with respect to the antitumour effects of aspirin.

Effect of aspirin use on gastric cancer incidence and survival: A systematic review and meta-analysis

Background and Aim

A number of recent studies have been published evaluating the chemopreventive effect of aspirin against gastric cancer, and an updated meta‐analysis is required to evaluate this relationship further. This study presents a meta‐analysis of studies examining the effect of aspirin on gastric cancer incidence and death.

Methods

The PUBMED and Cochrane Central Registration of Controlled Trials databases were searched for eligible studies published up to December 2018. Pooled risk ratios for gastric cancer incidence and death in aspirin users versus nonusers were determined using fixed‐ and random‐effects models. The influence of the frequency of aspirin use, duration of aspirin use, and geographic location on gastric cancer incidence was evaluated.

Results

The meta‐analysis comprised 33 studies with a total of 1 927 971 patients. The pooled risk ratios for gastric cancer incidence in the fixed‐ and random‐effects models were 0.890 (95% confidence interval, 0.871–0.909) and 0.826 (0.740–0.922), respectively. In Asia and North America, the maximum preventive benefit of aspirin use was observed with weekly or daily use. Aspirin use was most effective for noncardiac gastric cancer. The pooled risk ratios for gastric cancer death in the fixed‐ and random‐effects models were 0.798 (0.749–0.850) and 0.894 (0.780–1.024), respectively. Significant heterogeneity was observed among studies of gastric cancer incidence but not gastric cancer death.

Conclusion

Aspirin use may reduce the risk of gastric cancer incidence and death; however, the relationship may be limited to a specific frequency and duration of aspirin use and geographic location.

Beyond a chemopreventive reagent, aspirin is a master regulator of the hallmarks of cancer

PURPOSE

Aspirin, one of the most commonly used nonsteroidal anti-inflammatory drugs (NAIDS), not only shows cancer chemoprevention effects but also improves cancer therapeutic effects when combined with other therapies. Studies that focus on aspirin regulation of the hallmarks of cancer and the associated molecular mechanisms facilitate a more thorough understanding of aspirin in mediating chemoprevention and may supply additional information for the development of novel cancer therapeutic agents.

METHODS

The relevant literatures from PubMed have been reviewed in this article.

RESULTS

Current studies have revealed that aspirin regulates almost all the hallmarks of cancer. Within tumor tissue, aspirin suppresses the bioactivities of cancer cells themselves and deteriorates the tumor microenvironment that supports cancer progression. In addition to tumor tissues, blocking of platelet activation also contributes to the ability of aspirin to inhibit cancer progression. In terms of the molecular mechanism, aspirin targets oncogenes and cancer-related signaling pathways and activates certain tumor suppressors.

CONCLUSION

Beyond a chemopreventive agent, aspirin is a master regulator of the hallmarks of cancer.

A novel mechanism for the anticancer activity of aspirin and salicylates

Epidemiological studies indicate that long‑term aspirin usage reduces the incidence of colorectal cancer (CRC) and may protect against other non‑CRC associated adenocarcinomas, including oesophageal cancer. A number of hypotheses have been proposed with respect to the molecular action of aspirin and other non‑steroidal anti‑inflammatory drugs in cancer development. The mechanism by which aspirin exhibits toxicity to CRC has been previously investigated by synthesising novel analogues and derivatives of aspirin in an effort to identify functionally significant moieties. Herein, an early effect of aspirin and aspirin‑like analogues against the SW480 CRC cell line was investigated, with a particular focus on critical molecules in the epidermal growth factor (EGF) pathway. The present authors proposed that aspirin, diaspirin and analogues, and diflunisal (a salicylic acid derivative) may rapidly perturb EGF and EGF receptor (EGFR) internalisation. Upon longer incubations, the diaspirins and thioaspirins may inhibit EGFR phosphorylation at Tyr1045 and Tyr1173. It was additionally demonstrated, using a qualitative approach, that EGF internalisation in the SW480 cell line may be directed to endosomes by fumaryldiaspirin using early endosome antigen 1 as an early endosomal marker and that EGF internalisation may also be perturbed in oesophageal cell lines, suggestive of an effect not only restricted to CRC cells. Taken together and in light of our previous findings that the aspirin‑like analogues can affect cyclin D1 expression and nuclear factor‑κB localisation, it was hypothesized that aspirin and aspirin analogues significantly and swiftly perturb the EGFR axis and that the protective activity of aspirin may in part be explained by perturbed EGFR internalisation and activation. These findings may also have implications in understanding the inhibitory effect of aspirin and salicylates on wound healing, given the critical role of EGF in the response to tissue trauma.

The Cytotoxicity and Synergistic Potential of Aspirin and Aspirin Analogues Towards Oesophageal and Colorectal Cancer

Background

Oesophageal cancer (OC) is a deadly cancer because of its aggressive nature with survival rates that have barely improved in decades. Epidemiologic studies have shown that low-dose daily intake of aspirin can decrease the incidence of OC.

Methods

The toxicity of aspirin and aspirin derivatives to OC and a CRC cell line were investigated in the presence and absence of platins.

Results

The data in this study show the effects of a number of aspirin analogues and aspirin on OC cell lines that originally presented as squamous cell carcinoma (SSC) and adenocarcinoma (ADC). The aspirin analogues fumaryldiaspirin (PN517) and the benzoylsalicylates (PN524, PN528 and PN529), were observed to be more toxic against the OC cell lines than aspirin. Both quantitative and qualitative apoptosis experiments reveal that these compounds largely induce apoptosis, although some necrosis was evident with PN528 and PN529. Failure to recover following the treatment with these analogues emphasized that these drugs are largely cytotoxic in nature. The OE21 (SSC) and OE33 (ADC) cell lines were more sensitive to the aspirin analogues compared to the Flo-1 cell line (ADC). A non-cancerous oesophageal primary cells NOK2101, was used to determine the specificity of the aspirin analogues and cytotoxicity assays revealed that analogues PN528 and PN529 were selectively toxic to cancer cell lines, whereas PN508, PN517 and PN524 also induced cell death in NOK2101. In combination index testing synergistic interactions of the most promising compounds, including aspirin, with cisplatin, oxaliplatin and carboplatin against the OE33 cell line and the SW480 colorectal cancer (CRC) cell line were investigated. Compounds PN517 and PN524, and to a lesser extent PN528, synergised with cisplatin against OE33 cells. Cisplatin and oxaliplatin synergised with aspirin and PN517 when tested against the SW480 cell line.

Conclusion

These findings indicate the potential and limitations of aspirin and aspirin analogues as chemotherapeutic agents against OC and CRC when combined with platins

Crosstalk between NF-κB and Nucleoli in the Regulation of Cellular Homeostasis

Nucleoli are emerging as key sensors of cellular stress and regulators of the downstream consequences on proliferation, metabolism, senescence, and apoptosis. NF-κB signalling is activated in response to a similar plethora of stresses, which leads to modulation of cell growth and death programs. While nucleolar and NF-κB pathways are distinct, it is increasingly apparent that they converge at multiple levels. Exposure of cells to certain insults causes a specific type of nucleolar stress that is characterised by degradation of the PolI complex component, TIF-IA, and increased nucleolar size. Recent studies have shown that this atypical nucleolar stress lies upstream of cytosolic IκB degradation and NF-κB nuclear translocation. Under these stress conditions, the RelA component of NF-κB accumulates within functionally altered nucleoli to trigger a nucleophosmin dependent, apoptotic pathway. In this review, we will discuss these points of crosstalk and their relevance to anti-tumour mechanism of aspirin and small molecule CDK4 inhibitors. We will also briefly the discuss how crosstalk between nucleoli and NF-κB signalling may be more broadly relevant to the regulation of cellular homeostasis and how it may be exploited for therapeutic purpose.

Effect of long term aspirin use on the incidence of prostate cancer: A systematic review and meta-analysis

BACKGROUND

Previous studies found divergent effects of aspirin use on prostate cancer incidence, potentially due to studies with short durations of aspirin use and insufficient adjustment for screening.

METHODS

A systematic review on the association between aspirin use ≥3 years and incident prostate cancer was performed in accordance with the PRISMA and MOOSE criteria.

RESULTS

In the cohort studies, aspirin use for at least 3 years was associated with a lower incidence rate of prostate cancer (Odds ratio (OR) 0.88, 95% CI 0.80-0.97). No protective association was established for the case-control studies (OR 0.92, 95% CI 0.68-1.23). Subgroup analysis of advanced and aggressive cancers showed a protective association (OR 0.82, 95% CI 0.71-0.94 and OR 0.75, 95% CI 0.61-0.97).

CONCLUSION

This synthesis of observational studies suggests a potential protective association between long term aspirin use and incident prostate cancer. The current literature is highly heterogenous and suffers from inconsistent aspirin dose definition and measurement.

Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies

Background

Epidemiological studies have clarified the potential associations between regular aspirin use and cancers. However, it remains controversial on whether aspirin use decreases the risk of cancers risks. Therefore, we conducted an updated meta-analysis to assess the associations between aspirin use and cancers.

Methods

The PubMed, Embase, and Web of Science databases were systematically searched up to March 2017 to identify relevant studies. Relative risks (RRs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

Results

A total of 218 studies with 309 reports were eligible for this meta-analysis. Aspirin use was associated with a significant decrease in the risk of overall cancer (RR = 0.89, 95% CI: 0.87–0.91), and gastric (RR = 0.75, 95% CI: 0.65–0.86), esophageal (RR = 0.75, 95% CI: 0.62–0.89), colorectal (RR = 0.79, 95% CI: 0.74–0.85), pancreatic (RR = 0.80, 95% CI: 0.68–0.93), ovarian (RR = 0.89, 95% CI: 0.83–0.95), endometrial (RR = 0.92, 95% CI: 0.85–0.99), breast (RR = 0.92, 95% CI: 0.88–0.96), and prostate (RR = 0.94, 95% CI: 0.90–0.99) cancers, as well as small intestine neuroendocrine tumors (RR = 0.17, 95% CI: 0.05–0.58).

Conclusions

These findings suggest that aspirin use is associated with a reduced risk of gastric, esophageal, colorectal, pancreatic, ovarian, endometrial, breast, and prostate cancers, and small intestine neuroendocrine tumors.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4156-5) contains supplementary material, which is available to authorized users.

Aspirin inhibited the metastasis of colon cancer cells by inhibiting the expression of toll-like receptor 4

Background

The metastasis of colorectal cancer frequently tends to liver, which is one of the three leading causes of cancer-related deaths worldwide. Growing evidence showed that aspirin could effectively inhibit liver metastasis of colorectal cancer. However, the potential mechanism has not been fully understood.

Methods

Mouse splenic vein metastasis assay was used to examine the metastatic ability of colon cancer cells in vivo. And wound healing and transwell assay were applied to detect the metastasis potential of C26 and HCT116 colon cancer cell lines in vitro. RT-PCR and western blotting were used to explore Toll-like receptor 4 (TLR4) expression in colon cancer cell lines. The functions of TLR4 in the migration of the colon cancer cell line were analyzed by infecting cells with lentivirus containing TLR4 siRNA.

Results

We demonstrated that lipopolysaccharides (LPS) could enhance the metastasis potential of C26 and HCT116 colon cancer cell lines. However, aspirin effectively decreased the metastasis capacity of colon cancer cells in vitro and in vivo. We found that the enhancement of LPS on the migration of colon cancer cells by inducing epithelial-mesenchymal transition (EMT) phenotype demonstrated a TLR4-dependent manner. Aspirin treatment lead to the downregulation of TLR4 on C26 cells which resulted in the decrease of C26 cells migration and EMT phenotype that induced by LPS. Additionally, the inhibitory effect from aspirin on the expression of TLR4 on C26 cells leads to the downregulation of NF-κB.

Conclusion

The results of our study indicate that LPS origin from intestinal flora may promote the metastasis of colon cancer to liver and aspirin may inhibit the metastasis of colon cancer by inhibiting the expression of TLR4.

Caspase-4 is essential for saikosaponin a-induced apoptosis acting upstream of caspase-2 and γ-H2AX in colon cancer cells

Saikosaponin a (SSa), a bioactive phytochemical from Bupleurum, triggers sequential caspase-2 and caspase-8 activation, and thereby induces caspase-mediated apoptosis in human colon carcinoma (HCC) cells. However, the upstream mechanism of caspase-2 activation remains unknown. Therefore, we investigated the signaling mechanisms underlying SSa-induced caspase activation and apoptosis in HCC cells. SSa treatment triggered marked antitumor effects, especially in HCC cells, in a cell culture model and a mouse xenograft model. SSa also induced the activation of several endoplasmic reticulum (ER) stress signals. Specifically, caspase-4, a critical regulator of ER stress-induced apoptosis, was activated significantly after SSa treatment. Mechanistically, selective inhibition of caspase-4 suppressed SSa-induced apoptosis, colony inhibition, and the activation of caspase-3, -8, and -2, but not vice versa. Consistent with the important role of caspase-2 in the DNA damage response, SSa induced DNA damage, as evidenced by a cytokinesis-block micronucleus assay, single-cell gel electrophoresis, and an increase in the levels of γ-H2AX, a DNA damage marker. Moreover, inhibition of caspase-4 activation inhibited SSa-induced histone H2AX phosphorylation. Taken together, these results suggest that caspase-4 is an upstream regulator of SSa-induced DNA damage and caspase activation in HCC cells. Given that SSa-induced apoptosis appeared to be specific to certain cell types including HCC cells, SSa may be a promising cancer therapy agent in certain types of cancer.

Ex vivo treatment of patient biopsies as a novel method to assess colorectal tumour response to the MEK1/2 inhibitor, Selumetinib

Although an array of new therapeutics has emerged for the treatment of colorectal cancer, their use is significantly impacted by variability in patient response. Better pre-clinical models could substantially improve efficacy as it may allow stratification of patients into the correct treatment regime. Here we explore acute, ex vivo treatment of fresh, surgically resected human colorectal tumour biopsies as a novel pre-clinical model for identifying patient response to specific therapeutics. The MEK1/2 inhibitor, Selumetinib (AZD6244, ARRY-142886) was used as a tool compound. Firstly, we established an acute treatment protocol and demonstrated this protocol could differentiate phenotypic and pharmacodynamic responses to Selumetinib (0–3uM). We then used the protocol to evaluate Selumetinib response in tumours from 23 colon cancer patients. These studies revealed that the agent inhibited pERK1/2 phosphorylation in all tumours, caused a significant decrease in proliferation in 5/23 (22%) tumours, and that KRAS/BRAF mutant tumours were particularly sensitive to the anti-proliferative effects of the agent. These data are consistent with data from clinical trials of Selumetinib, suggesting that acute treatment of small tumour biopsies is worthy of further exploration as a pre-clinical model to evaluate colorectal cancer response to novel therapies.

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.

Aspirin Prevention of Colorectal Cancer: Focus on NF-κB Signalling and the Nucleolus

Overwhelming evidence indicates that aspirin and related non-steroidal anti-inflammatory drugs (NSAIDs) have anti-tumour activity and the potential to prevent cancer, particularly colorectal cancer. However, the mechanisms underlying this effect remain hypothetical. Dysregulation of the nuclear factor-kappaB (NF-κB) transcription factor is a common event in many cancer types which contributes to tumour initiation and progression by driving expression of pro-proliferative/anti-apoptotic genes. In this review, we will focus on the current knowledge regarding NSAID effects on the NF-κB signalling pathway in pre-cancerous and cancerous lesions, and the evidence that these effects contribute to the anti-tumour activity of the agents. The nuclear organelle, the nucleolus, is emerging as a central regulator of transcription factor activity and cell growth and death. Nucleolar function is dysregulated in the majority of cancers which promotes cancer growth through direct and indirect mechanisms. Hence, this organelle is emerging as a promising target for novel therapeutic agents. Here, we will also discuss evidence for crosstalk between the NF-κB pathway and nucleoli, the role that this cross-talk has in the anti-tumour effects of NSAIDs and ways forward to exploit this crosstalk for therapeutic purpose.

The role of aspirin in preventing colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers in the developed world and is the second leading cause of cancer-related mortality in the UK and USA. Regular use of aspirin can reduce cancer incidence, recurrence, metastasis and cancer-related mortality.

SOURCES OF DATA

Peer-reviewed journals, governmental and professional society publications.

AREAS OF AGREEMENT

There is a wide body of evidence from observational studies and randomized trials that aspirin reduces risk of CRC. There is a delay of several years between initiation and effect. There is interpersonal variation in aspirin metabolism but pharmacogenetic testing is not yet sufficiently sensitive or specific to justify routine use.

AREAS OF DISAGREEMENT

There is uncertainty about the optimal dose and the duration of aspirin. There is debate around use for the general population but there is growing consensus on use in those at increased risk of developing cancer.

GROWING POINTS

Understanding is growing of the possible mechanisms by which aspirin exerts its anticancer effects. Large-scale meta-analyses are quantifying the cost-benefit ratio in the general population. International trials are underway to assess the optimal dose in high-risk individuals and the role of aspirin as an adjuvant in those who present with a malignancy.

Aspirin Targets SIRT1 and AMPK to Induce Senescence of Colorectal Carcinoma Cells

Cancer therapies attempt to destroy the entire tumor, but this tends to require toxic compounds and high doses of radiation. Recently, considerable attention has focused on therapy-induced senescence (TIS), which can be induced in cancer cells by low doses of therapeutic drugs or radiation and provides a barrier to tumor development. However, the molecular mechanisms governing TIS remain elusive. Special attention has been paid to the potential chemopreventive effect of aspirin against human colorectal cancer. In this study, we investigated the effects of aspirin on TIS of human colorectal carcinoma (CRC) cells and show that it occurs via sirtuin 1 (SIRT1) and AMP-activated protein kinase (AMPK), two key regulators of cellular metabolism. Aspirin increased the senescence of CRC cells, increased the protein levels of SIRT1, phospho-AMPK (T172), and phospho-acetyl CoA carboxylase (S79), and reduced the cellular level of ATP. Small-interfering RNA-mediated downregulation or pharmacological inhibition of SIRT1 or AMPK significantly attenuated the aspirin-induced cellular senescence in CRC cells. In contrast, treatment with a SIRT1 agonist or an AMP analog induced cellular senescence. Remarkably, SIRT1 knockdown abrogated the aspirin-induced activation of AMPK, and vice versa. During the progression of aspirin-induced cellular senescence in CRC cells, SIRT1 showed increased deacetylase activity at a relatively early time point but was characterized by decreased activity with increased cytoplasmic localization at a later time point. Collectively, these novel findings suggest that aspirin could provide anticancer effects by inducing senescence in human CRC cells through the reciprocal regulation of SIRT1-AMPK pathways.

Aspirin blocks growth of breast tumor cells and tumor-initiating cells and induces reprogramming factors of mesenchymal to epithelial transition

Acetylsalicylic acid (ASA), also known as aspirin, a classic, nonsteroidal, anti-inflammatory drug (NSAID), is widely used to relieve minor aches and pains and to reduce fever. Epidemiological studies and other experimental studies suggest that ASA use reduces the risk of different cancers including breast cancer (BC) and may be used as a chemopreventive agent against BC and other cancers. These studies have raised the tempting possibility that ASA could serve as a preventive medicine for BC. However, lack of in-depth knowledge of the mechanism of action of ASA reshapes the debate of risk and benefit of using ASA in prevention of BC. Our studies, using in vitro and in vivo tumor xenograft models, show a strong beneficial effect of ASA in the prevention of breast carcinogenesis. We find that ASA not only prevents breast tumor cell growth in vitro and tumor growth in nude mice xenograft model through the induction of apoptosis, but also significantly reduces the self-renewal capacity and growth of breast tumor-initiating cells (BTICs)/breast cancer stem cells (BCSCs) and delays the formation of a palpable tumor. Moreover, ASA regulates other pathophysiological events in breast carcinogenesis, such as reprogramming the mesenchymal to epithelial transition (MET) and delaying in vitro migration in BC cells. The tumor growth-inhibitory and reprogramming roles of ASA could be mediated through inhibition of TGF-β/SMAD4 signaling pathway that is associated with growth, motility, invasion, and metastasis in advanced BCs. Collectively, ASA has a therapeutic or preventive potential by attacking possible target such as TGF-β in breast carcinogenesis.

Nuclear factor kappa B role in inflammation associated gastrointestinal malignancies

Nuclear factor kappa B (NF-κB) has an established role in the regulation of innate immunity and inflammation. NF-κB is also involved in critical mechanisms connecting inflammation and cancer development. Recent investigations suggest that the NF-κB signaling cascade may be the central mediator of gastrointestinal malignancies including esophageal, gastric and colorectal cancers. This review will explore NF-κB’s function in inflammation-associated gastrointestinal malignancies, highlighting its oncogenic contribution to each step of carcinogenesis. NF-κB’s role in the inflammation-to-carcinoma sequence in gastrointestinal malignancies warrants stronger emphasis upon targeting this pathway in achieving greater therapeutic efficacy.

Chemopreventive effects of oplopantriol A, a novel compound isolated from Oplopanax horridus, on colorectal cancer

Oplopanax horridus is a North American botanical that has received limited investigations. We previously isolated over a dozen of the constituents from O. horridus, and among them oplopantriol A (OPT A) is a novel compound. In this study, we firstly evaluated the in vivo chemoprevention activities of OPT A using the xenograft colon cancer mouse model. Our data showed that this compound significantly suppressed tumor growth with dose-related effects (p < 0.01). Next, we characterized the compound's growth inhibitory effects in human colorectal cancer cell lines HCT-116 and SW-480. With OPT A treatment, these malignant cells were significantly inhibited in both a concentration- and time-dependent manner (both p < 0.01). The IC50 was approximately 5 µM for HCT-116 and 7 µM for SW-480 cells. OPT A significantly induced apoptosis and arrested the cell cycle at the G2/M phase. From further mechanism explorations, our data showed that OPT A significantly upregulated the expression of a cluster of genes, especially the tumor necrosis factor receptor family and caspase family, suggesting that the tumor necrosis factor-related apoptotic pathway plays a key role in OPT A induced apoptosis.

Aspirin and colorectal cancer: back to the future

Abundant epidemiologic evidence indicates that regular and long-term use of aspirin is associated with a significant reduction in the incidence of colorectal cancer. The long duration of aspirin needed to prevent colorectal cancer is believed to be due to inhibition of precursor lesions known as adenomas, the recurrence of which is inhibited by aspirin in randomized trials. Aspirin intake has also been associated with a statistically significant improvement in patient survival after curative resection of colorectal cancer in large observational studies. In these cohorts, the survival benefit of aspirin was shown to depend upon the level of COX-2 expression in the primary colorectal cancer. More recent analysis of patient tumors from these observational cohorts suggests that the benefit of aspirin may be limited to specific molecular subtypes. Aspirin intake following colorectal cancer resection was associated with a significant improvement of survival in patients whose tumors carried mutant, but not wild-type, copies of the phosphoinositide 3-kinase (PI3KCA) gene, especially tumors that overexpressed COX-2. A mechanistic explanation is suggested by the finding that inhibition of COX-mediated prostaglandin E2 synthesis by aspirin attenuates PI3K signaling activity that is known to regulate cancer cell proliferation and survival. Aspirin has also been shown to reduce the incidence of colorectal cancers bearing wild-type, but not mutant alleles of the BRAF(V600E) oncogene. Although provocative, the potential utility of these molecular markers for predicting aspirin efficacy awaits prospective evaluation in clinical trials. If validated, these findings may support a personalized approach to using aspirin for the therapy of colorectal cancer.

Aspirin-induced Bcl-2 translocation and its phosphorylation in the nucleus trigger apoptosis in breast cancer cells

Here, we report that B-cell lymphoma 2 (Bcl-2) is a novel target molecule of aspirin in breast cancer cells. Aspirin influenced the formation of a complex by Bcl-2 and FKBP38 and induced the nuclear translocation of Bcl-2 and its phosphorylation. These events inhibited cancer cell proliferation and subsequently enhanced MCF-7 breast cancer cell apoptosis. Bcl-2 knockdown using small interfering RNA (siRNA) delayed apoptotic cell death, which correlated with increased proliferation following aspirin exposure. In contrast, Bcl-2 overexpression enhanced the onset of aspirin-induced apoptosis, which was also associated with a significant increase in Bcl-2 phosphorylation in the nucleus. Therefore, this study may provide novel insight into the molecular mechanism of aspirin, particularly its anticancer effects in Bcl-2- and estrogen receptor-positive breast cancer cells.

Identification of potential anticancer compounds from Oplopanax horridus

Oplopanax horridus is a plant native to North America. Previous reports have demonstrated that this herb has antiproliferative effects on cancer cells but study mostly focused on its extract or fractions. Because there has been limited phytochemical study on this herb, its bioactive compounds are largely unknown. We recently isolated and identified 13 compounds, including six polyynes, three sesquiterpenes, two steroids, and two phenolic acids, of which five are novel compounds. In this study, we systemically evaluated the anticancer effects of compounds isolated from O. horridus. Their antiproliferative effects on a panel of human colorectal and breast cancer cells were determined using the MTS assay. Cell cycle distribution and apoptotic effects were analyzed by flow cytometry. The in vivo antitumor effect was examined using a xenograft tumor model. Among the 13 compounds, strong antiproliferative effects were observed from falcarindiol and a novel compound oplopantriol A. Falcarindiol showed the most potent antiproliferative effects, significantly inducing pro-apoptosis and cell cycle arrest in the S and G2/M phases. The anticancer potential of falcarindiol was further verified in vivo, significantly inhibiting HCT-116 tumor growth in an athymic nude mouse model at 15 mg/kg. We also analyzed the relationship between polyyne structures and their pharmacological activities. We observed that both the terminal hydroxyl group and double bond obviously affected their anticancer potential. Results from this study supplied valuable information for future semi-synthesis of polyyne derivatives to develop novel cancer chemopreventive agents.

The proapoptotic effect of traditional and novel nonsteroidal anti-inflammatory drugs in mammalian and yeast cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) have long been used to treat pain, fever, and inflammation. However, mounting evidence shows that NSAIDs, such as aspirin, have very promising antineoplastic properties. The chemopreventive, antiproliferative behaviour of NSAIDs has been associated with both their inactivation of cyclooxygenases (COX) and their ability to induce apoptosis via pathways that are largely COX-independent. In this review, the various proapoptotic pathways induced by traditional and novel NSAIDs such as phospho-NSAIDs, hydrogen sulfide-releasing NSAIDs and nitric oxide-releasing NSAIDs in mammalian cell lines are discussed, as well as the proapoptotic effects of NSAIDs on budding yeast which retains the hallmarks of mammalian apoptosis. The significance of these mechanisms in terms of the role of NSAIDs in effective cancer prevention is considered.

PI3K is required for the physical interaction and functional inhibition of NF-κB by β-catenin in colorectal cancer cells

Activation of β-catenin and PI3K pathways are crucial for the oncogenesis of colorectal cancer (CRC). It remains controversial whether these two pathways function independently or cooperatively in the development and progression of CRC. We showed previously that β-catenin inhibited NF-κB activation by interacting with p65 and this inhibitory interaction involved an unidentified cellular protein. In this study, we found that the PI3K effect on NF-κB activity is dependent on the level of β-catenin in CRC cells. PI3K promoted NF-κB activity in the β-catenin-low RKO cells; whereas it inhibited NF-κB activity in the β-catenin-high HCT116, DLD-1, and SW480 cells. We showed that PI3K is required for the physical interaction and functional inhibition of NF-κB by β-catenin. Inhibition of PI3K released NF-κB suppression in β-catenin-high CRC cells, which conferred these cells with susceptibility to TNFα- and Fas-induced apoptosis. This is consistent with the observation showing that the level of β-catenin and activated Akt are both inversely correlated with the expression of Fas, a downstream target of NF-κB, in CRC specimens. Mechanistically, the PI3K subunit p85 formed a complex with β-catenin and NF-κB. Inhibition of PI3K disrupted the complex formation, leading to NF-κB activation. Our study not only provides new insight into the cross-talk among PI3K, β-catenin and NF-κB signaling pathways but also indicates that targeting PI3K may yield therapeutic efficacy in treating β-catenin-high CRC.

Inhibition of COX-2 in colon cancer modulates tumor growth and MDR-1 expression to enhance tumor regression in therapy-refractory cancers in vivo

Higher cyclooxygenase 2 (COX-2) expression is often observed in aggressive colorectal cancers (CRCs). Here, we attempt to examine the association between COX-2 expression in therapy-refractory CRC, how it affects chemosensitivity, and whether, in primary tumors, it is predictive of clinical outcomes. Our results revealed higher COX-2 expression in chemoresistant CRC cells and tumor xenografts. In vitro, the combination of either aspirin or celecoxib with 5-fluorouracil (5-FU) was capable of improving chemosensitivity in chemorefractory CRC cells, but a synergistic effect with 5-FU could only be demonstrated with celecoxib. To examine the potential clinical significance of these observations, in vivo studies were undertaken, which also showed that the greatest tumor regression was achieved in chemoresistant xenografts after chemotherapy in combination with celecoxib, but not aspirin. We also noted that these chemoresistant tumors with higher COX-2 expression had a more aggressive growth rate. Given the dramatic response to a combination of celecoxib + 5-FU, the possibility that celecoxib may modulate chemosensitivity as a result of its ability to inhibit MDR-1 was examined. In addition, assessment of a tissue microarray consisting of 130 cases of CRCs revealed that, in humans, higher COX-2 expression was associated with poorer survival with a 68% increased risk of mortality, indicating that COX-2 expression is a marker of poor clinical outcome. The findings of this study point to a potential benefit of combining COX-2 inhibitors with current regimens to achieve better response in the treatment of therapy-refractory CRC and in using COX-2 expression as a prognostic marker to help identify individuals who would benefit the greatest from closer follow-up and more aggressive therapy.

Paraptosis and NF-κB activation are associated with protopanaxadiol-induced cancer chemoprevention

Background

Protopanaxadiol (PPD) is a triterpenoid that can be prepared from steamed ginseng. PPD possesses anticancer potential via caspase-dependent apoptosis. Whether paraptosis, a type of the caspase-independent cell death, is also induced by PPD has not been evaluated.

Methods

Cell death, the cell cycle and intracellular reactive oxygen species (ROS) were analyzed by flow cytometry after staining with annexin V/PI, PI/RNase or H2DCFDA. We observed morphological changes by crystal violet staining assay. Mitochondrial swelling was measured by ultraviolet–visible spectrophotometry. The activation of NF-κB was measured by luciferase reporter assay.

Results

At comparable concentrations of 5-fluorouracil, PPD induced more cell death in human colorectal cancer cell lines HCT-116 and SW-480. We demonstrated that PPD induced paraptosis in these cancer cells. PPD treatment significantly increased the percentage of cancer cells with cytoplasmic vacuoles. After the cells were treated with PPD and cycloheximides, cytoplasmic vacuole generation was inhibited. The paraptotic induction effect of PPD was also supported by the results of the mitochondrial swelling assay. PPD induced ROS production in cancer cells, which activated the NF-κB pathway. Blockage of ROS by NAC or PS-1145 inhibited the activation of NF-κB signaling.

Conclusions

PPD induces colorectal cancer cell death in part by induction of paraptosis. The anticancer activity of PPD may be enhanced by antioxidants such as green tea, which also inhibit the activation of NF-κB signaling.

Aspirin inhibits colon cancer cell and tumor growth and downregulates specificity protein (Sp) transcription factors

Acetylsalicylic acid (aspirin) is highly effective for treating colon cancer patients postdiagnosis; however, the mechanisms of action of aspirin in colon cancer are not well defined. Aspirin and its major metabolite sodium salicylate induced apoptosis and decreased colon cancer cell growth and the sodium salt of aspirin also inhibited tumor growth in an athymic nude mouse xenograft model. Colon cancer cell growth inhibition was accompanied by downregulation of Sp1, Sp3 and Sp4 proteins and decreased expression of Sp-regulated gene products including bcl-2, survivin, VEGF, VEGFR1, cyclin D1, c-MET and p65 (NFκB). Moreover, we also showed by RNA interference that β-catenin, an important target of aspirin in some studies, is an Sp-regulated gene. Aspirin induced nuclear caspase-dependent cleavage of Sp1, Sp3 and Sp4 proteins and this response was related to sequestration of zinc ions since addition of zinc sulfate blocked aspirin-mediated apoptosis and repression of Sp proteins. The results demonstrate an important underlying mechanism of action of aspirin as an anticancer agent and, based on the rapid metabolism of aspirin to salicylate in humans and the high salicylate/aspirin ratios in serum, it is likely that the anticancer activity of aspirin is also due to the salicylate metabolite.

IκBKβ and NFκB1, NSAID use and risk of colorectal cancer in the Colon Cancer Family Registry

The NFκB-signaling pathway regulates cell proliferation and inflammation. Activation of the pathway is implicated in the etiology of colorectal cancer (CRC). NSAIDs may reduce CRC risk partially through a nuclear factor-kappa B (NFκB)-dependent pathway. In this study, we investigated associations between 34 NFκB1 and 8 IκBKβ tagSNPs and CRC risk and examined interactions with non-steroidal anti-inflammatory drug (NSAID) use. Using conditional logistic regression, we investigated these associations among 1584 incident CRC cases and 2516 sibling controls from the Colon Cancer Family Registry. Three IκBKβ SNPs were associated with a statistically significant lower colorectal or colon cancer risk: rs9694958 (A>G intron 5) (colorectal: OR(hzv) = 0.26(0.07-0.99), P(trend) = 0.048, P(adj) = 0.25), rs10958713 (A>C intron 19) (colon: OR(hzv) = 0.62(0.42-0.92), P(trend) = 0.005, P(adj) = 0.03) and rs5029748 (C>A intron 2) (colon: OR(het) = 0.72(0.56-0.91), P(trend) = 0.01, P(adj) = 0.08). We replicated trends associated with NFκB1 and IκBKβ variants identified in a previous study (rs4648110 (T>A intron 22), rs13117745 (G>A intron 5) and rs3747811 (T>A intron 1)). IκBKβ's rs6474387 (C>T intron 20) and rs11986055 (A>C intron 2) showed substantially lower colon cancer risk among current NSAID users (P(interaction) = 0.01 and P(interaction) = 0.045, respectively), whereas NFκB1's rs230490 (G>A 5' (outside UTR)) and rs997476 (C>A 3' (outside UTR)) showed higher CRC risk among current NSAID users (P(interaction) = 0.01 and P(interaction) = 0.03, respectively). These findings suggest that variants in NFκB1 and IκBKβ are associated with CRC risk and NSAIDs may function partially through an NFκB-dependent pathway. The SNPs identified here should be considered for future functional studies and may be useful in designing a pharmacogenetic approach to preventive NSAID use.

In silico predicative studies for cytotoxic potential of NSAIDs using self-organizing molecular field analysis

Antiproliferative potential of nonsteroidal anti-inflammatory drugs (NSAIDs) has generated an immense interest among the scientific fraternity to assess its broader role in the chemoprevention of colon cancer. Due to serious adverse events associated with the chemotherapy, NSAIDs have been exploited as adjuvants to synergize the cytotoxic potential of conventional chemotherapeutic agents at low-dose regimens. The present investigation has been focused on in silico model generation for in vitro cytotoxicity activity of the clinically active NSAIDs using self-organizing molecular field analysis (SOMFA) studies. A statistically validated robust model for a diverse group of NSAIDs having flexibility in structure and cytotoxicity activity was obtained using SOMFA. The statistical measures having good cross-validated correlation coefficient r (2) (cv) (.8291), noncross-validated correlation coefficient r (2) values (.8686), and high F test value (41.8722) proved significance in the generated model. Analysis of 3-dimensional quantitative structure activity relationship (3D-QSAR) models through electrostatic and shape grids provided additional valuable information regarding shape and electrostatic potential influence on in vitro cytotoxicity profile. The analysis of SOMFA results provided a better insight about the generation of molecular architecture of novel NSAIDs yet to be synthesized, with optimum in vitro cytotoxicity activity and improved therapeutic profile.

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.

Epigenetic deregulation of the COX pathway in cancer

Inflammation is a major cause of cancer and may condition its progression. The deregulation of the cyclooxygenase (COX) pathway is implicated in several pathophysiological processes, including inflammation and cancer. Although, its targeting with nonsteroidal antiinflammatory drugs (NSAIDs) and COX-2 selective inhibitors has been investigated for years with promising results at both preventive and therapeutic levels, undesirable side effects and the limited understanding of the regulation and functionalities of the COX pathway compromise a more extensive application of these drugs. Epigenetics is bringing additional levels of complexity to the understanding of basic biological and pathological processes. The deregulation of signaling and biosynthetic pathways by epigenetic mechanisms may account for new molecular targets in cancer therapeutics. Genes of the COX pathway are seldom mutated in neoplastic cells, but a large proportion of them show aberrant expression in different types of cancer. A growing body of evidence indicates that epigenetic alterations play a critical role in the deregulation of the genes of the COX pathway. This review summarizes the current knowledge on the contribution of epigenetic processes to the deregulation of the COX pathway in cancer, getting insights into how these alterations may be relevant for the clinical management of patients.

Targeting NF-κB and HIF-1 pathways for the treatment of cancer: part I

The process of chronic inflammation is a common link which connects different kinds of environmental pollutants and infections with tumorigenesis. Transcription factor NF-κB is a common final target for many inflammatory and cell proliferation pathways, independent of the source of stimuli (e.g., cytokines, growth factors, environmental carcinogens, radiation, hypoxia, bacteria, and viruses). Over-activation of NF-κB has been confirmed in many tumors, resulting in worse prognosis for patient survival. Therefore, inhibition of cellular pathways for NF-κB activation is nowadays considered as a promising anti-cancer therapy and is extensively studied in clinical trials, or even has been adopted as an approved therapy in some kinds of cancer.