Aspirin-induced nuclear translocation of NFkappaB and apoptosis in colorectal cancer is independent of p53 status and DNA mismatch repair proficiency

A Contemporary Review on the Critical Role of Nonsteroidal Anti-inflammatory Agents in Colorectal Cancer Therapy

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) are widely recognized as effective pain relievers and function by inhibiting the cyclooxygenase enzyme (COXs). Moreover, they have been found to participate in various cellular processes through different signaling pathways, such as WNT, MAPK, NF-κB, and PI3K/AKT/mTOR. This makes them potential candidates for chemoprevention of several malignancies, particularly colorectal cancer (CRC). However, the use of NSAIDs in cancer prevention and treatment is a complex issue due to their adverse effects and gastrointestinal toxicity. Therefore, it is crucial to explore combination therapies that can minimize side effects while maximizing synergistic effects with other agents and to evaluate the success rate of such approaches in both pre-clinical and clinical studies. In this review, we aim to provide an overview of the effects of NSAIDs in the prevention and treatment of CRC. We will focus on elucidating the possible mechanisms of action of these drugs, the signaling pathways involved in CRC, and the potential synergistic effects when combined with other therapeutic agents.

Salicylate induces AMPK and inhibits c-MYC to activate a NRF2/ARE/miR-34a/b/c cascade resulting in suppression of colorectal cancer metastasis

Aspirin and its active metabolite salicylate have emerged as promising agents for the chemoprevention of colorectal cancer (CRC). Moreover, aspirin suppresses the progression of established CRCs. However, the underlying molecular mechanisms are not completely understood. Here we found that salicylate induces the expression of the miR-34a and miR-34b/c genes, which encode tumor suppressive microRNAs, in a p53-independent manner. Salicylate activated AMPK, thereby activating NRF2, which directly induced miR-34a/b/c expression via ARE motifs. In addition, salicylate suppressed c-MYC, a known repressor of NRF2-mediated transactivation, via activating AMPK. The suppression of c-MYC by salicylate was necessary for NRF2-mediated activation of miR-34a/b/c. Inactivation of miR-34a/b/c largely abrogated the inhibitory effects of salicylate on migration, invasion and metastasis formation by CRC cells. In the future, aspirin and its derivates may be used therapeutically to activate miR-34a and miR-34b/c in tumors that have lost p53.

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.

Aspirin, ibuprofen, and reduced risk of advanced colorectal adenoma incidence and recurrence and colorectal cancer in the PLCO Cancer Screening Trial

BACKGROUND

Studying the differential impact of aspirin and other nonsteroidal anti-inflammatory drugs across the stages of colorectal neoplasia from early adenoma to cancer is critical for understanding the benefits of these widely used drugs.

METHODS

With 13 years of follow-up, the authors prospectively evaluated the association between aspirin and ibuprofen use and incident distal adenoma (1221 cases), recurrent adenoma (862 cases), and incident colorectal cancer (CRC; 2826 cases) among men and women in the population-based Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. With multivariable-adjusted models, odds ratio (ORs) and 95% confidence intervals (CIs) for adenoma incidence and recurrence and hazard ratios (HRs) and 95% CIs for incident CRC were determined.

RESULTS

The authors observed a significantly reduced risk of incident adenoma with ibuprofen use (≥30 vs <4 pills per month: OR, 0.76 [95% CI, 0.60-0.95]; Ptrend = .04), particularly advanced adenoma (OR, 0.48 [95% CI, 0.28-0.83]; Ptrend = .005). Among those with a previous adenoma detected through screening, aspirin use was associated with a decreased risk of advanced recurrent adenoma (≥30 vs <4 pills per month: OR, 0.56 [95% CI, 0.36-0.87]; Ptrend = 0.006). Both aspirin (HR, 0.88 [95% CI, 0.81-0.96]; Ptrend <.0001) and ibuprofen use (HR, 0.81 [95% CI, 0.70-0.93); Ptrend = 0.003) ≥30 versus <4 pills per month were significantly associated with reduced CRC risk.

CONCLUSIONS

In this large prospective study with long-term follow-up, a beneficial role for not only aspirin, but also ibuprofen, in preventing advanced adenoma and curbing progression to recurrence and cancer among older adults was observed.

Aspirin for prevention of colorectal cancer in the elderly: friend or foe?

Cancer is the leading cause of death among men and women aged 60-79 years. Colorectal cancer is the third most common cancer in males and the second most common in females, with about 0.8 million deaths worldwide per year. Individuals older than 50 years account for 20-50% of colonic adenomas. Several measures have been proposed to decrease colorectal cancer risks, such as an increase in dietary fiber, use of aspirin, and physical activity. Nonsteroidal anti-inflammatory drugs have been proposed as protective agents against the development of colorectal cancer and colorectal adenomas. Aspirin was the first pharmacological agent endorsed by the United States Preventive Services Task Force screening for colorectal cancer chemoprevention. Although studies have shown up to 40% colorectal cancer risk reduction in individuals at average risk, data regarding this benefit are inconsistent. Several recent studies show that prophylactic use of aspirin in elderly subjects may not be beneficial in preventing the occurrence of colorectal cancers. Given the risks associated with aspirin, such as non-fatal and fatal bleeding events, aspirin's role should be redefined, especially in individuals at risk of bleeding. This review provides a discussion of the recent studies on the role of aspirin use in elderly individuals at risk of colorectal cancer.

Concurrent use of aspirin with osimertinib is associated with improved survival in advanced EGFR-mutant non-small cell lung cancer

BACKGROUND

Osimertinib is the treatment of choice for advanced EGFR-mutant non-small cell lung cancer (NSCLC). However, novel strategies to improve the duration of disease control are still urgently needed. Aspirin has been shown to decrease cancer incidence and improve outcomes in various malignancies. Therefore, we evaluated a cohort of patients who received osimertinib with or without concurrent use of aspirin to assess whether the addition of aspirin may lead to improved clinical outcomes.

METHODS

MD Anderson Cancer Center GEMINI database was retrospectively queried for EGFR-mutant NSCLC patients who received osimertinib with or without concurrent use of aspirin for progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 365 patients were identified including 77 which had concurrent use of aspirin. Patients in the aspirin-osimertinib group had significantly improved PFS (21.3 vs 11.6 months; HR, 0.52; 95 % CI, 0.38-0.70) and OS (Not reached vs 32.3 months; HR, 0.56; 95 % CI, 0.35-0.91) compared to osimertinib group. In subgroup analyses, the aspirin-associated PFS benefit was observed in patients with and without central nervous system (CNS) metastases, as well as in osimertinib first-line setting and in subsequent line setting. The median PFS in EGFR 19Del patients was longer than EGFR L858R patients with osimertinib, and when aspirin was added, the median PFS significantly improved in both groups regardless of lines of therapy. The benefit from aspirin was independent of age, gender, TP53 mutational status, or PD-L1 positivity.

CONCLUSION

Concurrent aspirin use with osimertinib in EGFR-mutant NSCLC patients was associated with improved survival, regardless of lines of therapy, CNS metastatic status, EGFR mutation type, age, gender, TP53, and PD-L1 status.

Identification of a novel TIF-IA-NF-κB nucleolar stress response pathway

p53 as an effector of nucleolar stress is well defined, but p53 independent mechanisms are largely unknown. Like p53, the NF-κB transcription factor plays a critical role in maintaining cellular homeostasis under stress. Many stresses that stimulate NF-κB also disrupt nucleoli. However, the link between nucleolar function and activation of the NF-κB pathway is as yet unknown. Here we demonstrate that artificial disruption of the PolI complex stimulates NF-κB signalling. Unlike p53 nucleolar stress response, this effect does not appear to be linked to inhibition of rDNA transcription. We show that specific stress stimuli of NF-κB induce degradation of a critical component of the PolI complex, TIF-IA. This degradation precedes activation of NF-κB and is associated with increased nucleolar size. It is mimicked by CDK4 inhibition and is dependent upon a novel pathway involving UBF/p14ARF and S44 of the protein. We show that blocking TIF-IA degradation blocks stress effects on nucleolar size and NF-κB signalling. Finally, using ex vivo culture, we show a strong correlation between degradation of TIF-IA and activation of NF-κB in freshly resected, human colorectal tumours exposed to the chemopreventative agent, aspirin. Together, our study provides compelling evidence for a new, TIF-IA-NF-κB nucleolar stress response pathway that has in vivo relevance and therapeutic implications.

Inhibition of SIRT1 deacetylase and p53 activation uncouples the anti-inflammatory and chemopreventive actions of NSAIDs

Background

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been proposed as chemopreventive agents for many tumours; however, the mechanism responsible for their anti-neoplastic activity remains elusive and the side effects due to cyclooxygenase (COX) inhibition prevent this clinical application.

Methods

Molecular biology, in silico, cellular and in vivo tools, including innovative in vivo imaging and classical biochemical assays, were applied to identify and characterise the COX-independent anti-cancer mechanism of NSAIDs.

Results

Here, we show that tumour-protective functions of NSAIDs and exisulind (a sulindac metabolite lacking anti-inflammatory activity) occur through a COX-independent mechanism. We demonstrate these NSAIDs counteract carcinogen-induced proliferation by inhibiting the sirtuin 1 (SIRT1) deacetylase activity, augmenting acetylation and activity of the tumour suppressor p53 and increasing the expression of the antiproliferative gene p21. These properties are shared by all NSAIDs except for ketoprofen lacking anti-cancer properties. The clinical interest of the mechanism identified is underlined by our finding that p53 is activated in mastectomy patients undergoing intraoperative ketorolac, a treatment associated with decreased relapse risk and increased survival.

Conclusion

Our study, for the first-time, links NSAID chemopreventive activity with direct SIRT1 inhibition and activation of the p53/p21 anti-oncogenic pathway, suggesting a novel strategy for the design of tumour-protective drugs.

NF-κB pathways in the development and progression of colorectal cancer

Nuclear factor-κB (NF-κB) has been widely implicated in the development and progression of cancer. In colorectal cancer (CRC), NF-κB has a key role in cancer-related processes such as cell proliferation, apoptosis, angiogenesis, and metastasis. The role of NF-κB in CRC is complex, owed to the cross talk with other signaling pathways. Although there is sufficient evidence gained from cell lines and animal models that NF-κB is involved in cancer-related processes, because of a lack of studies in human tissue, the clinical evidence of its importance is limited in patients with CRC. This review summarizes evidence relating to how NF-κB is involved in the development and progression of CRC and comments on future work to be carried out.

Long-term exposure of Mytilus galloprovincialis to diclofenac, Ibuprofen and Ketoprofen: Insights into bioavailability, biomarkers and transcriptomic changes

Non-steroidal anti-inflammatory drugs (NSAIDs) represent a growing concern for marine ecosystems due to their ubiquitous occurrence and documented adverse effects on non-target organisms. Despite the remarkable efforts to elucidate bioaccumulation and ecotoxicological potential under short-term conditions, limited and fragmentary information is available for chronic exposures. In this study bioavailability, molecular and cellular effects of diclofenac (DIC), ibuprofen (IBU) and ketoprofen (KET) were investigated in mussels Mytilus galloprovincialis exposed to the realistic environmental concentration of 2.5 μg/L for up to 60 days. Results indicated a significant accumulation of DIC and IBU but without a clear time-dependent trend; on the other hand, KET concentrations were always below the detection limit. Analyses of a large panel of molecular, biochemical and cellular biomarkers highlighted that all investigated NSAIDs caused alterations of immunological parameters, genotoxic effects, modulation of lipid metabolism and changes in cellular turn-over. This study provided the evidence of long-term ecotoxicological potential of NSAIDs, further unraveling the possible hazard for wild marine organisms.

Insights into the regulation of neuronal viability by nucleophosmin/B23

The vastness of the neuronal network that constitutes the human brain proves challenging when trying to understand its complexity. Furthermore, due to the senescent state they enter into upon maturation, neurons lack the ability to regenerate in the face of insult, injury or death. Consequently, their excessive death can be detrimental to the proper functioning of the brain. Therefore, elucidating the mechanisms regulating neuronal survival is, while challenging, of great importance as the incidence of neurological disease is becoming more prevalent in today's society. Nucleophosmin/B23 (NPM) is an abundant and ubiquitously expressed protein that regulates vital cellular processes such as ribosome biogenesis, cell proliferation and genomic stability. As a result, it is necessary for proper embryonic development, but has also been implicated in many cancers. While highly studied in the context of proliferative cells, there is a lack of understanding NPM's role in post-mitotic neurons. By exploring its role in healthy neurons as well as its function in the regulation of cell death and neurodegeneration, there can be a better understanding of how these diseases initiate and progress. Owing to what is thus far known about its function in the cell, NPM could be an attractive therapeutic target in the treatment of neurodegenerative diseases.

Tolfenamic Acid Suppresses Inflammatory Stimuli-Mediated Activation of NF-κB Signaling

Tolfenamic acid (TA) is a traditional non-steroid anti-inflammatory drug (NSAID) and has been broadly used for the treatment of migraines. Nuclear factor kappa B (NF-κB) is a sequence-specific transcription factor and plays a key role in the development and progression of inflammation and cancer. We performed the current study to investigate the underlying mechanisms by which TA suppresses inflammation focusing on NF-κB pathway in TNF-α stimulated human normal and cancer cell lines and lipopolysaccharide (LPS)-stimulated mouse macrophages. Different types of human cells (HCT116, HT-29 and HEK293) and mouse macrophages (RAW264.7) were pre-treated with different concentrations of TA and then exposed to inflammatory stimuli such as TNF-α and LPS. Transcriptional activity of NF-κB, IκB-α-degradation, p65 translocation and mitogen-activated protein kinase (MAPK) activations were measured using luciferase assay and Western blots. Pre-treatment of TA repressed TNF-α- or LPS-stimulated NF-κB transactivation in a dose-dependent manner. TA treatment reduced degradation of IκB-α and subsequent translocation of p65 into nucleus. TA significantly down-regulated the phosphorylation of c-Jun N-terminal kinase (JNK). However, TA had no effect on NF-κB signaling and JNK phosphorylation in HT-29 human colorectal cancer cells. TA possesses anti-inflammatory activities through suppression of JNK/NF-κB pathway in different types of cells.

Oral acetylsalicylic acid and prevalence of actinic keratosis

Objective: To investigate the influence of a regular oral use of acetylsalicylic acid in the prevalence of actinic keratosis. Methods: A case-control study with dermatologic outpatients above 50 years of age assessed between 2009 and 2011. Cases were defined as those who had been under regular use of oral acetylsalicylic acid for more than six consecutive months. The assessment focused on: age, sex, skin-type, tobacco smoking, use of medication, occurrence of individual or family skin cancer, and sunscreen and sun exposure habits. Actinic keratoses were counted in the medial region of the face and upper limbs. Counts were adjusted by co-variables based on a generalized linear model. Results: A total of 74 cases and 216 controls were assessed. The median time of acetylsalicylic acid use was 36 months. Cases differed from controls as to the highest age, highest prevalence of use of angiotensin-converting enzyme inhibitors and fewer keratosis on the face and on the upper limbs (p<0.05). The multivariate model showed that the use of acetylsalicylic acid was associated to lower counts of face actinic keratosis and upper-limb erythematous actinic keratosis (p<0.05), regardless of other risk factors. Conclusion: The regular use of oral acetylsalicylic acid for more than six months was associated to a lower prevalence of actinic keratosis, especially facial and erythematous ones.

Mechanisms of action of non-steroidal anti-inflammatory drugs (NSAIDs) and mesalazine in the chemoprevention of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. Although conclusive evidence is still lacking, epidemiologic studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has chemopreventive properties against CRC. Similarly, regular consumption of mesalazine, a drug structurally related to NSAIDs, seems to reduce the risk of CRC in patients with ulcerative colitis. These observations are supported by a large body of experimental data showing the ability of such drugs to inhibit multiple pathways that sustain colon carcinogenesis. This review summarizes the current information on the molecular mechanisms by which NSAIDs and mesalazine could interfere with CRC cell growth and survival.

Mechanisms of action of non-steroidal anti-inflammatory drugs (NSAIDs) and mesalazine in the chemoprevention of colorectal cancer

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. Although conclusive evidence is still lacking, epidemiologic studies suggest that long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has chemopreventive properties against CRC. Similarly, regular consumption of mesalazine, a drug structurally related to NSAIDs, seems to reduce the risk of CRC in patients with ulcerative colitis. These observations are supported by a large body of experimental data showing the ability of such drugs to inhibit multiple pathways that sustain colon carcinogenesis. This review summarizes the current information on the molecular mechanisms by which NSAIDs and mesalazine could interfere with CRC cell growth and survival.

Molecular pathways: adipose inflammation as a mediator of obesity-associated cancer

The increasing rate of obesity worldwide is predicted to be associated with a surge in diseases. Notably, obesity has been linked to approximately 20% of cancer cases in the United States; obesity is associated with both increased risk and worse outcomes after diagnosis. Altered levels of circulating factors are strongly implicated, including insulin, insulin-like growth factor 1, leptin, adiponectin, and interleukin-6 (IL-6). In addition, increasing attention has focused on the consequences of local adipose inflammation. Inflammatory foci characterized by crown-like structures consisting of dead adipocytes encircled by macrophages occur in white adipose depots, including the breast tissue, of most overweight and obese women. Saturated fatty acids, released as a consequence of obesity-associated lipolysis, induce macrophage activation via Toll-like receptor 4, thereby stimulating NF-κB signaling. This, in turn, activates transcription of proinflammatory genes including COX-2, IL-6, IL-1β, and TNFα. Elevated levels of proinflammatory mediators cause both local and systemic effects. Of particular relevance with regard to breast cancer is increased transcription of the CYP19 gene encoding aromatase, the rate-limiting enzyme for estrogen synthesis. Notably, this obesity-inflammation-aromatase axis provides a plausible explanation for increased rates of postmenopausal, hormone receptor-positive breast cancer associated with obesity and hence may offer targets for interventions to attenuate risk or improve prognosis. Potential approaches include weight reduction, exercise, and suppression of obesity-driven signaling pathways using pharmaceutical or dietary agents. A key future goal is to identify biomarkers that accurately report adipose inflammation, both for identification of at-risk individuals and to assess the efficacy of interventions. Clin Cancer Res; 19(22); 6074-83. ©2013 AACR.

Gene transcription and biomarker responses in the clam Ruditapes philippinarum after exposure to ibuprofen

Pharmaceuticals are a class of emerging environmental contaminants that continuously enter aquatic environments. Presently, little information is available about the effects of these substances on non-target organisms, such as bivalves. We investigated the effects of ibuprofen (IBU) on the clam Ruditapes philippinarum. Clams were exposed for 1, 3, 5 and 7 days to 0, 100 and 1000 μgIBU/L, and established biomarker responses (haemolymph lysozyme, gill acetylcholinesterase and digestive gland superoxide dismutase activities) as well as digestive gland transcriptome were evaluated. A two-way ANOVA revealed significant effects of both "IBU concentration" and "exposure duration" on biomarker responses. Overall, the enzyme activities were generally lower in IBU-exposed clams than in controls. Although limited knowledge of the mollusc transcriptome makes it difficult to interpret the effects of IBU on clams, the gene transcription analysis using DNA microarrays enabled the identification of the putative molecular mode of action of the IBU. The functional analysis of differentially transcribed genes suggests that IBU can interfere with various signalling pathways in clams, such as arachidonic acid metabolism, apoptosis, peroxisomal proliferator-activated receptors, and nuclear factor-kappa B. In addition, several genes involved in the metabolism of xenobiotics (e.g., glutathione S-transferase, sulfotransferase, cytochrome P450) were also found to be significantly affected by IBU exposure. In summary, the integrated approach of gene transcription analysis and biomarker responses facilitated the elucidation of the putative mechanisms of action of IBU in non-target species.

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.

Pharmacology and cellular/molecular mechanisms of action of aspirin and non-aspirin NSAIDs in colorectal cancer

Colorectal cancer (CRC) and colorectal adenomas have in common a dysfunctional adenomatous polyposis coli suppressor gene (APC). This allows for activation of the oncogenic Wnt/β-catenin pathway, resulting in cytosolic accumulation of β-catenin, its translocation to the nucleus and action as a cofactor for stimulation of gene transcription. Pharmacological approaches of CRC-chemoprevention are focused to prevention of this β-catenin-mediated oncogenic signalling. Among upregulated genes in tumour tissue is COX-2 which synthesises large amounts of PGE(2). PGE(2) inhibits apoptosis, acts proinflammatory and immunosuppressive and stimulates tumour angiogenesis and proliferation. In addition, COX-2 causes oxidation (activation) of cocarcinogens. Aspirin and non-aspirin NSAIDs inhibit COX-2, subsequent PGE(2) formation and action by transcriptional and non-transcriptional mechanisms. These also include inhibition of generation of sphingosine-1-phosphate, an amplifier of these reactions and stimulation of NSAID-induced gene (NAG-1) which acts as an inhibitor. Aspirin additionally acetylates COX-2, resulting in generation of 'aspirin-triggered' lipoxins (ATL), a new class of anti-inflammatory/antitumour compounds. COX-1 inhibition might also contribute to antitumour effects of aspirin, for example at low-dose aspirin. Experimental evidence suggests additional COX independent actions of aspirin and non-aspirin NSAIDs on oncogenic signalling. This includes modifications of transcription factors (NFκB), induction of apoptosis and DNA stabilization. In comparison to non-aspirin NSAIDs (sulindac, indomethacin) and coxibs (celecoxib), aspirin has the advantage of concomitant antiplatelet effects while NSAIDs rather have a thrombogenic potential. Though these actions of aspirin have to be balanced against an increased bleeding tendency, aspirin is currently the most attractive candidate for clinical CRC chemoprevention. Open questions, such as dose, (minimum) duration of treatment and the individual risk/benefit ratio are subjects of prospective randomized trials which are underway.

Established and novel NF-κB inhibitors lead to downregulation of TLR3 and the proliferation and cytokine secretion in HNSCC

The transcriptional activation of NF-κB signalling has been identified as a major pathway involved in inflammation and tumor aggressiveness in a number of human cancers. Here we identify the impact of miscellaneous known and so far unknown NF-κB inhibitors originating from different drug classes on the function and proliferation of HNSCC. In detail: HNSCC cell lines were exposed to Acetylsalicylic Acid (ASA), Celecoxib, Dexamethasone, Curcumin and EPs 7630. Our major interest was to detect upstream alterations in cell signalling after applying NF-κB inhibiting substances. The inhibition of NF-κB signalling leads to an upstream regulation of Toll-like-receptor 3 (TLR3), a predominant receptor driving cell expansion. We find a marked downregulation of TLR3 and IKK complex, documenting upstream responses to NF-κB inhibition by every agent tested. In a second step we further analyse proliferation, cytokine production and alterations in the expression of downstream proteins such as cyclin D1 and c-Myc. Our data demonstrate decreased proliferation in response to incubation with aforementioned agents. Modulation of TLR3 and NF-κB expression is accompanied by altered profiles of IL-6 and IL-8 which are relevant cytokines in HNSCC progression. Proto-oncogenes cyclin D1 and c-myc are downregulated by all substances. Apart from the interplay of cytokines and TLR3, we substantiated EPs 7630 as a new and natural NF-κB inhibitor.

Nucleolar NF-κB/RelA mediates apoptosis by causing cytoplasmic relocalization of nucleophosmin

In a number of contexts, and particularly in response to cellular stress, stimulation of the NF-kappaB (NF-κB) pathway promotes apoptosis. One mechanism underlying this pro-apoptotic activity is nucleolar sequestration of RelA, which is reported to cause cell death by repressing NF-κB-driven transcription. Here, we identify a novel and distinct nucleolar activity of RelA that induces apoptosis. We demonstrate, using a viral nucleolar localization signal (NoLS)-RelA fusion protein, that direct targeting of RelA to the nucleolus mediates apoptosis, independent of NF-κB transcriptional activity. We demonstrate a requirement for nucleophosmin (NPM, B23.1) in this apoptotic effect, and the apoptotic effect of stress-induced nucleolar RelA. We show by multiple approaches that nucleolar translocation of RelA is causally involved in the relocalization of NPM from the nucleolus to the cytoplasm and that RelA-induced cytoplasmic NPM mediates apoptosis by facilitating the mitochondrial accumulation of BAX. These data uncover a novel stress-response pathway and mechanism by which RelA promotes apoptosis, independent of its effects on NF-κB transcriptional activity. These findings are relevant to the design of novel anticancer agents that target RelA to this compartment.

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.

Non-steroidal anti-inflammatory drug use and colorectal polyps in the Prostate, Lung, Colorectal, And Ovarian Cancer Screening Trial

OBJECTIVES

Non-steroidal anti-inflammatory drugs (NSAIDs) have been documented in animal and human studies to reduce risk for colorectal cancer and adenomatous polyps, but risk modification for subgroups of the population and effects on hyperplastic polyps have been less studied.

METHODS

Data on recent use of two frequently ingested NSAIDs, aspirin and ibuprofen, were collected at baseline from participants aged 55-74 years in the 10 centers of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). Participants randomized to the intervention arm of the trial received a flexible sigmoidoscopy during a baseline examination. Follow-up of detected polyps was accomplished outside the Trial setting and relevant records were sought and abstracted. Cases (n=4,017) included subjects with a biopsy-proven polyp in the left side of the colon (descending colon, sigmoid, and rectum) detected as a consequence of PLCO screening; controls (n=38,396) were subjects with no left-sided colon polyp.

RESULTS

Regular use of aspirin (≥ 4 times/month) in the past year was inversely associated with hyperplastic polyps (odds ratios (OR)=0.8, 95% confidence interval (CI)=0.7-0.9), adenomatous polyps (OR=0.8, 95% CI=0.8-0.9), and advanced adenomas (OR=0.8, 95% CI=0.7-0.9). As frequency of aspirin use increased, the prevalence of polyps decreased significantly for each histological classification (P for trend ≤ 0.0004). Similar patterns were found for adenomas and ibuprofen. Overall protection was consistent in both the descending colon or sigmoid and the rectum, but more evident in males. In males, the OR for heavy use of combined aspirin and ibuprofen (≥ 2 times/day) was 0.6 (95% CI=0.5-0.8), as opposed to 0.9 (95% CI=0.8-1.1) in females. The protective effects of NSAIDs for females were apparent only among those with body mass index (BMI) <25 (OR=0.8, 95% CI=0.7-1.0 for regular use of NSAIDs; P interaction=0.04). We also found a slightly stronger protection of NSAIDs in the 70-74 years age group compared with those aged 55-69 years.

CONCLUSIONS

This study of a large general risk population supports previous work that recent use of aspirin and ibuprofen is associated with a decreased risk of colorectal adenomas and demonstrates that this protective effect may be stronger in certain population subgroups and is also evident for aspirin and hyperplastic polyps.

Unique aspects of transcriptional regulation in neurons--nuances in NFkappaB and Sp1-related factors

The unique physiology and function of neurons create differences in their cellular physiology, including their regulation of gene expression. We began several years ago exploring the relationships between the NFκB transcription factor, neuronal survival, and glutamate receptor activation in telencephalic neurons. These studies led us to conclude that this population of cells is nearly incapable of activating the NFκB that is nonetheless expressed at reasonable levels. A subset of the κB cis elements are instead bound by members of the Sp1 family in neurons. Also surprising was our discovery that Sp1 itself, typically described as ubiquitous, is severely restricted in expression within forebrain neurons; Sp4 seems to be substituted during neuronal differentiation. These findings and their implications for neuronal differentiation – as well as potential dedifferentiation during degenerative processes – are discussed here.

Spontaneous regression of colorectal cancer: a review of cases from 1900 to 2005

INTRODUCTION

Spontaneous regression of cancer is an exceptional but well-documented biological event. Further understanding of this phenomenon and harnessing of the mechanisms involved will have significant preventative and therapeutic implications.

DISCUSSION

In this review, the literature of spontaneous regression of colon or rectal cancer is reviewed from 1965 to 2005 to update reviews by Everson et al., Boyd and Challis et al. By adding to these, the author reports the entire series of colorectal cancer, which underwent documented spontaneous regression from 1900 to 2005. The demographic and pathologic characteristics, the details of regression and the outcome of reported cases are presented and discussed. Special emphasis is placed on identifying possible causes hypothesized by authors for occurrence of regression. Possible mechanisms operating to affect these regressions are also discussed.

Aspirin blocks proliferation in colon cells by inducing a G1 arrest and apoptosis through activation of the checkpoint kinase ATM

Colorectal cancer (CRC) is the most common gastrointestinal malignancy. Most of the clinical data on CRC prevention have come from the use of aspirin. Besides inhibition of cyclooxygenases, aspirin has a diversity of molecular effects that counteract colon carcinogenesis. Aspirin restrains cell proliferation by inducing a G1 arrest in colorectal cells. To determine which cell cycle checkpoint pathways are involved in this response, colorectal cell lines wild-type or defective for p53 and p21Waf1/Cip1 were treated with aspirin or the anti-proliferative drug sulindac sulfide, then assayed for proliferative activity, for cell cycle progression and apoptosis, for the activation and phosphorylation of checkpoint components and for the transcriptional up-regulation of p21Waf1/Cip1 and Bax. Aspirin and sulindac sulfide induced a G1 arrest within 48 h. While all cell lines responded in a comparable way to sulindac sulfide, the aspirin-induced G1 arrest was dependent on p21Waf1/Cip1--as cells lacking the cyclin-dependent kinase inhibitor failed to show this arrest--and on ataxia-telangiectasia-mutated kinase (ATM)--as the inhibitor caffeine abrogated the checkpoint. Moreover, aspirin induced cell death mainly in cells expressing p53. Aspirin induced the phosphorylation of p53 at residue Ser15 within 8 h in a caffeine-dependent manner, and also caused the activation of checkpoint kinase 2 and the cleavage of caspase 7. Our results suggest that aspirin induces a G1 arrest and apoptosis by activating p53 and p21Waf1/Cip1 in an ATM-dependent way. By activating these checkpoint pathways, aspirin may restrain uncontrolled proliferation of colorectal cells, enhance their response to stresses such as DNA damage and promote entry of abnormal cells into apoptosis.

p38-mediated inactivation of cyclin D1/cyclin-dependent kinase 4 stimulates nucleolar translocation of RelA and apoptosis in colorectal cancer cells

Aberrant nuclear factor-kappaB (NF-kappaB) signaling plays a role in cancer initiation and progression; thus, it represents a potential therapeutic target. We previously identified a mechanism of repression of NF-kappaB transcriptional activity and induction of apoptosis in colon cancer cells involving nuclear/nucleolar translocation of the RelA (p65) component of NF-kappaB. This response was stimulated by cellular stress-inducing agents, including aspirin, but not by tumor necrosis factor. Here, we investigate the upstream molecular mechanisms responsible for nucleolar targeting of RelA and show that aspirin activates the p38 mitogen-activated protein kinase (MAPK) pathway in colorectal cancer cells. We also show that aspirin causes rapid, ubiquitin-dependent degradation of cyclin D1, a known p38 target. Aspirin-induced p38 activation preceded cyclin D1 degradation, which was then followed by activation of the NF-kappaB pathway, suggesting a causative link. Indeed, chemical p38 inhibition (PD169316) and small interfering RNA directed against p38 blocked aspirin-induced cyclin D1 degradation, nucleolar translocation of RelA, and apoptosis. Furthermore, chemical inhibition of the cyclin D1/cyclin-dependent kinase 4 (CDK4) kinase complex, used as a surrogate for cyclin D1 degradation, caused nucleolar translocation of RelA, repression of kappaB-driven transcription, and apoptosis, thereby reproducing the effects of aspirin. In addition, we found that aspirin and the CDK4 inhibitor induced nucleolar translocation of RelA and apoptosis through a common mechanism involving the NH(2)-terminal nucleolar localization signal. Collectively, these data suggest that aspirin causes inhibition of cyclin D1/CDK4 through the p38 MAPK pathway. This inhibition stimulates the NF-kappaB pathway to induce nucleolar translocation of RelA and apoptosis. These novel findings have considerable relevance to the rational design of novel chemotherapeutic and chemopreventative strategies.

Apoptotic Effect of Celecoxib Dependent Upon p53 Status in Human Ovarian Cancer Cells

Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, induces the apoptosis in various cancers in COX-2 dependent and/or independent manners. The p53 protein is mutated in 50% of all human tumors and plays a key role in apoptosis, cell cycle, and the expression of several proteins. In ovarian cancer, the rate of p53 mutation has been shown to be very high and associated with poor prognosis. To explore the importance of functional status of p53 in apoptosis by celecoxib in ovarian cancer cells, the cellular response to celecoxib was determined in SK-OV3 ovarian cancer cells with null type p53 and PA-1 with wild-type p53. Our results showed that celecoxib inhibited cell growth more in PA-1 than in SK-OV3. The underlying antiproliferative mechanism may differ between these two cell types dependent upon the functional status of p53, which plays integral roles in regulating cell cycle and survival. Higher sub-G1 was shown in PA-1 than in SK-OV3 in response to celecoxib (PA-1 versus SK-OV3; 60.28% versus 6.69%). Caspase -8, -9, and -3 were activated in PA-1 cells, but not in SK-OV3 cells. These results suggest that death receptor and mitochondria-mediated apoptotic pathways may be involved in celecoxib-induced apoptosis dependent upon the functional status of p53. Our article demonstrated that the celecoxib effectively inhibited cell growth and induced apoptosis in human ovarian cancer cells with wild-type p53. Thus, apoptotic effect by celecoxib seemed to be different dependent upon the functional status of p53.

Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy

NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.

Induction of spermidine/spermine N1-acetyltransferase (SSAT) by aspirin in Caco-2 colon cancer cells

Epidemiological, experimental and clinical results suggest that aspirin and other NSAIDs (non-steroidal anti-inflammatory drugs) inhibit the development of colon cancer. It has been shown that the NSAID sulindac induces apoptosis and suppresses carcinogenesis, in part, by a mechanism leading to the transcriptional activation of the gene encoding SSAT (spermidine/spermine N1-acetyltransferase), a rate-limiting enzyme in polyamine catabolism. In the present study, we show that a variety of NSAIDs, including aspirin, sulindac, ibuprofen and indomethacin, can induce SSAT gene expression in Caco-2 cells. Aspirin, at physiological concentrations, can induce SSAT mRNA via transcriptional initiation mechanisms. This induction leads to increased SSAT protein levels and enzyme activity. Promoter deletion analysis of the 5' SSAT promoter-flanking region led to the identification of two NF-kappaB (nuclear factor kappaB) response elements. Electrophoretic mobility-shift assays showed binding of NF-kappaB complexes at these sequences after aspirin treatment. Aspirin treatment led to the activation of NF-kappaB signalling and increased binding at these NF-kappaB sites in the SSAT promoter, hence providing a potential mechanism for the induction of SSAT by aspirin in these cells. Aspirin-induced SSAT ultimately leads to a decrease in cellular polyamine content, which has been associated with decreased carcinogenesis. These results suggest that activation of SSAT by aspirin and different NSAIDs may be a common property of NSAIDs that plays an important role in their chemopreventive actions in colorectal cancer.