Review article: the potential of combinational regimen with non-steroidal anti-inflammatory drugs in the chemoprevention of colorectal cancer

Lipid-lowering drugs and cancer: an updated perspective

Statins and non-statin medications used for the management of dyslipidemia have been shown to possess antitumor properties. Since the use of these drugs has steadily increased over the past decades, more knowledge is required about their relationship with cancer. Lipid-lowering agents are heterogeneous compounds; therefore, it remains to be revealed whether anticancer potential is a class effect or related to them all. Here, we reviewed the literature on the influence of lipid-lowering medications on various types of cancer during development or metastasis. We also elaborated on the underlying mechanisms associated with the anticancer effects of antihyperlipidemic agents by linking the reported in vivo and in vitro studies.

Non-steroidal anti-inflammatory drugs and biomarkers: A new paradigm in colorectal cancer

Colorectal cancer is a sporadic, hereditary, or familial based disease in its origin, caused due to diverse set of mutations in large intestinal epithelial cells. Colorectal cancer (CRC) is a common and deadly disease that accounts for the 4^th worldwide highly variable malignancy. For the early detection of CRC, the most common predictive biomarker found endogenously are KRAS and ctDNA/cfDNA along with SEPT9 methylated DNA. Early detection and screening for CRC are necessary and multiple methods can be employed to screen and perform early diagnosis of CRC. Colonoscopy, an invasive method is most prevalent for diagnosing CRC or confirming the positive result as compared to other screening methods whereas several non-invasive techniques such as molecular analysis of breath, urine, blood, and stool can also be performed for early detection. Interestingly, widely used medicines known as non-steroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation have reported chemopreventive impact on gastrointestinal malignancies, especially CRC in several epidemiological and preclinical types of research. NSAID acts by inhibiting two cyclooxygenase enzymes, thereby preventing the synthesis of prostaglandins (PGs) and causing NSAID-induced apoptosis and growth inhibition in CRC cells. This review paper majorly focuses on the diversity of natural and synthetic biomarkers and various techniques for the early detection of CRC. An approach toward current advancement in CRC detection techniques and the role of NSAIDs in CRC chemoprevention has been explored systematically. Several prominent governing mechanisms of the anti-cancer effects of NSAIDs and their synergistic effect with statins for an effective chemopreventive measure have also been discussed in this review paper.

Enabling the drug combination of celecoxib through a spherical co-agglomeration strategy with controllable and stable drug content and good powder properties

Combining celecoxib with other chemopreventive drugs is a promising method of chemoprevention for cancer, especially for colorectal cancer. However, the traditional drug combination approaches are restricted with high-cost apparatus, complex and numerous unit operations. This work aims to develop an efficient spherical co-agglomeration strategy for celecoxib in combination with lovastatin, which can achieve drug combination in a single crystallization unit. The ternary solvent system was determined based on molecular simulation, and then a stable spherical agglomeration process was developed through the design of molar fraction of anti-solvent (MFA) and stirring rate to produce spherical agglomerates with high sphericity (84.2-89.9 %) and narrow size distribution. On this basis, celecoxib-benzoic acid spherical co-agglomerates were designed to form a complete spherical co-agglomeration strategy, which includes solvent system selection, spherical agglomeration and spherical co-agglomeration. Finally, celecoxib-lovastatin spherical co-agglomerates with synergistic efficacy were successfully produced by this strategy, with controllable and stable drug content (fluctuation < 2.7 %), good powder properties, and improved tabletability.

The Effect of Smoking on the Number and Type of Rectal Aberrant Crypt Foci (ACF)-First Identifiable Precursors of Colorectal Cancer (CRC)

Background: The problem of smoking and its influence on the occurrence of precursors and advanced colorectal cancer is often discussed in the medical literature. Tobacco smoke can provide a non-nutritional source of polycyclic hydrocarbons and other substances which, when combined with an incorrect diet, may play a role in promoting carcinogenesis at the level of the genetic control mechanism. The aim of our study was to assess the effect of smoking on the frequency and type of aberrant crypt foci (ACF) in the rectum and polyps in the large intestine in people who smoke more than 20 cigarettes a day for more than 20 years. Methods and Findings: A colonoscopy combined with rectal mucosa staining with 0.25% methylene blue was performed in 131 patients. Each of the study participants gave informed consent to participate in the study. Three bioptates were collected from the foci defined macroscopically as ACF; in cases where there were fewer foci, the number of collected foci was respectively lower. On the colonoscopy day, patients completed the questionnaire regarding epidemiological data used for analysis of factors affecting the occurrence of ACF in the study group. The number of ACF in the colon was divided into three groups: −ACF < 5, 5 < ACF < 10, ACF > 10. In the statistical analysis, numerical data were presented and real numbers, range of arrhythmic means, mean standard deviation, and results of probability distribution. The Student’s test, U test, and chi2 were applied in order to determine the significance of differences of means and frequency of events in both groups. The level of significance was set at α = 0.05. Statistica 7.1 and Excel 2010 were used. Most smokers are in the age groups between 51–70 years. In the youngest (31–40 years), single ACF appear first (ACF <5) ACF in the number of 5–10 appear a little later (around 50 years of age) and dynamically increase, reaching a maximum at the age of 60–65.ACF in the number >10 appear at the latest age (55 years old) and their number gradually increases with age (linear growth). The probability of occurrence of ACF in all groups is greater in smokers, and the difference for the ACF group 5-10 and ACF >10 is statistically significant with a significance level of p < 0.05. Apart from ACF normal, all types of ACF are more likely in this group than in non-smokers and these differences are statistically significant with p < 0.05. Conclusions: Smoking has a significant impact on the number and type of rectal ACF. Smokers have a greater number of ACFs in the rectum than non-smokers, and the most common type is hyperplastic ACF. Smokers are more likely to develop polyps in all sections of the colon compared to non-smokers.

Statin therapy and association with ovarian cancer risk in the New England Case Control (NEC) study

Statins are widely used to lower blood cholesterol and reduce risk for cardiovascular diseases, but attention has recently focused on a role in cancer prevention or therapy. Here we present data from a large case-control study addressing whether statin use can lower the risk for epithelial ovarian cancer (EOC). Between 1992 and 2008, data including medications used for at least 6 months were collected from 2,040 cases with EOC and 2,100 frequency-matched controls without the disease who participated in the New England Case Control study. We used unconditional logistic regression controlling for matching factors and potential confounders to examine the association between statin use and the risk for EOC. Overall, women who used statins had 32% lower risk of ovarian cancer compared to non-users (Odds ratio (OR) 0.68, 95% Confidence Interval (CI): 0.54-0.85), adjusting for the matching factors and other covariates. The reduced risk was most apparent in women taking a lipophilic statin who began use after age 49, and who had used them 2-4.9 years. Statin use was associated with lower risks for both serous and non-serous histologic subtypes with the strongest effect seen for mucinous and mixed epithelial subtypes. The association became apparent about a decade after the introduction of statins and did not appear to be confounded by indications for use of statins or medications used concomitantly. In this case-control study, statins were found to lower the risk for both serous and non-serous EOC and especially mucinous EOC.

Albumin concentrations plus neutrophil lymphocyte ratios for predicting overall survival after curative resection for gastric cancer

Background

In patients with gastric cancer (GC), survival is poor, given the late diagnosis. Risk-stratifying these patients earlier could help improve care. We determined whether combining preoperative albumin concentration and the neutrophil lymphocyte ratio (COA-NLR) could predict overall survival (OS) better than other prognostic indexes.

Methods

We calculated the COA-NLR and other prognostic indexes with data obtained within 1 week before surgery in a retrospective analysis of patients with GC undergoing curative resection between September 2000 and November 2012. Patients with concentrations of hypoalbuminemia above 35 g/L and an NLR value of 2.3 or higher were given a score of 2. Patients with one of these conditions or neither were allocated scores of 1 or 0, respectively. Patients were monitored until July 2014.

Results

OS in the 873 eligible patients was 44.9% in patients with a COA-NLR score of 0, 29.8% in patients with a score of 1, and 20.3% in patients with a score of 2 (P<0.001). The COA-NLR score was independently associated with OS (hazard ratio, 1.35; 95% confidence interval, 1.12 to 1.63; P=0.002). Moreover, the area under the receiver operating characteristics curve was 0.62 for the COA-NLR, which was significantly higher (<0.001) than that of the NLR ratio (0.60), the Glasgow prognostic score (0.58), and the platelet lymphocyte ratio (0.54). The COA-NLR was especially accurate for patients with stage I–II GC and the three values (0, 1, and 2) divided patients into subgroups more accurately than did the other indexes (area under the curve value: 0.66, P<0.001).

Conclusion

The preoperative COA-NLR index is useful for predicting postoperative OS in patients with GC and can be used to guide targeted therapy.

PPARγ suppressed Wnt/β-catenin signaling pathway and its downstream effector SOX9 expression in gastric cancer cells

Wnt signaling pathway activation plays a critical role in biological processes of tumor progression. SOX9 belongs to the sry-related high-mobility group box (SOX) family and is a key transcription factor in the development and differentiation of multiple cell lineages. The purpose of this study was to investigate whether suppression of Wnt signaling pathway by PPARγ gene affects target SOX9 gene expression. The pEGFP-N1-PPARγ overexpression recombinant plasmid was structured by molecular biology technology. The overexpression plasmid and empty vector pEGFP-N1 were transfected into three types of human gastric cancer cell lines, with different levels of differentiation, MKN-28, SGC-7901 and BGC-823. The PPARγ, β-catenin and SOX9 mRNA levels and proteins were examined by real-time PCR and Western blot analysis. The pEGFP-N1-PPARγ recombinant plasmid was constructed and transfected into MKN-28, SGC-7901 and BGC-823 successfully. High expression of PPARγ (p < 0.05) for transfection recombinant plasmid group induced obviously decreased expression of β-catenin (p < 0.05), whereas SOX9 expression decreased significantly (p < 0.05) compared with the transfection empty vector group and normal comparison group. PPARγ can suppress β-catenin expression in Wnt signaling pathway and its downstream effector SOX9 expression in gastric cancer cells.

Synergistic Effect of Sulindac and Simvastatin on Apoptosis in Lung Cancer A549 Cells through AKT-Dependent Downregulation of Survivin

Purpose

Non-steroidal anti-inflammatory drugs (NSAIDs) and statins are potential chemopreventive or chemotherapeutic agents. The mechanism underlying the deregulation of survivin by NSAIDs and statins in human non-small cell lung cancer cells has not been elucidated. In this study, we investigated the synergistic interaction of sulindac and simvastatin in lung cancer A549 cells.

Materials and Methods

Cell viability was measured by an MTT assay, while the expression of apoptotic markers, AKT, and survivin in response to sulindac and simvastatin was examined by Western blotting. DNA fragmentation by apoptosis was analyzed by flow cytometry in A549 cells. Reactive oxygen species (ROS) generation was measured by flow cytometry using H₂DCFDA and MitoSOX Red, and the effects of pretreatment with N-acetylcysteine were tested. The effects of AKT on survivin expression in sulindac- and simvastatin-treated cells were assessed. Survivin was knocked down or overexpressed to determine its role in apoptosis induced by sulindac and simvastatin.

Results

Sulindac and simvastatin synergistically augmented apoptotic activity and intracellular ROS production in A549 cells. Inhibition of AKT by siRNA or LY294002 inhibited survivin, while AKT overexpression markedly increased survivin expression, even in the presence of sulindac and simvastatin. Moreover, survivin siRNA enhanced sulindac- and simvastatininduced apoptosis. In contrast, survivin upregulation protected against sulindac- and simvastatin-induced apoptosis.

Conclusion

Combined treatment with sulindac and simvastatin augmented their apoptotic potential in lung cancer cells through AKT signaling-dependent downregulation of survivin. These results indicate that sulindac and simvastatin may be clinically promising therapies for the prevention of lung cancer.

Inverse association of colorectal cancer prevalence to serum levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in a large Appalachian population

Background

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are persistent environmental contaminants that affect metabolic regulation, inflammation, and other factors implicated in the development and progression of colorectal cancer (CRC). However, the link between these compounds and CRC remains unknown. In this cross-sectional study, we investigated the association of CRC diagnosis to PFOA and PFOS blood levels in a large Appalachian population.

Methods

Participants were 47,359 adults ≥ 21 years of age and residing in six PFOA-contaminated water districts in the mid-Ohio Valley (N = 47,151 cancer-free adults, 208 cases of primary CRC). All participants completed a comprehensive health survey between 2005 and 2006; serum levels of PFOA, PFOS, and a range of other blood markers were also measured. Medical history was assessed via self report and cancer diagnosis confirmed via chart review.

Results

CRC showed a strong inverse, dose–response association with PFOS serum levels (odds ratio (OR) adjusted for potential confounders = 0.2, 95% confidence interval (CI) 0.2,0.3) for highest vs. lowest quartile of PFOS, P-trend < 0.00001) and a significant, but more modest inverse association with PFOA (adjusted OR = 0.6 (CI 0.4, 0.9) for highest vs. lowest quartile, P-trend = 0.001). These inverse associations were stronger in those diagnosed within the previous 6 years and resident in the same water district for a minimum of 10–15 years preceding assessment. The relationship between PFOA and CRC was also more pronounced in men and leaner adults, and showed a stronger linear trend at lower exposure levels.

Conclusions

In this large cross-sectional study, we found a strong, inverse association between PFOS and likelihood of CRC diagnosis and a significant, although more modest inverse association between PFOA and CRC. If confirmed in prospective investigations, these findings may aid in identifying new strategies for CRC prevention and treatment and inform future studies regarding mechanisms underlying CRC pathogenesis.

Regulation of TRAIL receptor expression by β-catenin in colorectal tumours

Tumour-necrosis-factor-related apoptosis-inducing ligand (TRAIL) is being investigated as a targeted cancer therapeutic and the expression of its pro-apoptotic receptors, DR4 and DR5, increases during colorectal carcinogenesis. This study investigated the role of β-catenin in the regulation of these receptors. In human colorectal adenoma and carcinoma cell lines, downregulation of β-catenin resulted in lower total DR4 and DR5 protein levels. Similarly, cell membrane expression of DR4 and DR5 was reduced after downregulation of β-catenin in colon carcinoma cells, whereas induction of β-catenin in HeLa cells led to increased cell membrane expression of DR4 and DR5. Downregulation of β-catenin decreased the recombinant human TRAIL sensitivity of human colon carcinoma cells. Activation of the transcription factor T-cell factor-4 (TCF-4) is an important function of β-catenin. Dominant-negative TCF-4 overexpression, however, did not significantly affect TRAIL receptor expression or recombinant human TRAIL sensitivity. Human colorectal adenomas (N = 158) with aberrant (cytoplasmic and nuclear) β-catenin expression had a higher percentage of immunohistochemical DR4 and DR5 staining per tumour (mean: 73 and 88%, respectively) than those with membranous β-catenin staining only (mean: 50 and 70%, respectively, P < 0.01 for both). Furthermore, aberrant β-catenin staining co-localized with DR4 and DR5 expression in 92% of adenomas. In 53 human colorectal carcinomas, aberrant β-catenin expression was present in most cases and DR4/5 expression was largely homogenous. Similarly, in adenomas from APC(min) mice, cytoplasmic β-catenin staining co-localized with staining for the murine TRAIL death receptor. In conclusion, the gradual increase in TRAIL receptor expression during colorectal carcinogenesis is at least partially mediated through increased β-catenin expression, independently of TCF-4-signalling.

Reduced esophageal cancer incidence in statin users, particularly with cyclo-oxygenase inhibition

AIM: To examine the association between statin use and the development of esophageal cancer

METHODS: We performed a systematic review and meta-analysis. Multiple databases (Pubmed, EMBASE, Cochrane Library, Web of Science, Wiley Interscience and Google Scholar) were systematically searched for studies reporting the association of statin use and the development of esophageal cancer. Literature searching and data abstraction were performed independently by two separate researchers. The quality of studies reviewed was evaluated using the Newcastle-Ottawa Quality assessment scale. Meta-analysis on the relationship between statin use and cancer incidence was performed. The effect of the combination of statin plus a cyclo-oxygenase inhibitor was also examined.

RESULTS: Eleven studies met eligibility criteria, 9 high and 2 medium quality. All were observational studies. Studies examining adenocarcinoma development in Barrett’s oesophagus included 317 cancers and 1999 controls, population-based studies examining all esophageal cancers included 371203 cancers and 6083150 controls. In the Barrett’s population the use of statins (OR = 0.57; 95%CI: 0.43-0.75) and cyclo-oxygenase inhibitors (OR = 0.59; 95%CI: 0.45-0.77) were independently associated with a reduced incidence of adenocarcinoma. Combined use of a statin plus cyclo-oxygenase inhibitor was associated with an even lower adenocarcinoma incidence (OR = 0.26; 95%CI: 0.1-0.68). There was more heterogeneity in the population-based studies but pooled adjusted data showed that statin use was associated with a lower incidence of all combined esophageal cancers (OR = 0.81; 95%CI: 0.75-0.88).

CONCLUSION: Statin use in patients with Barrett’s oesophagus is associated with a significantly lower incidence of adenocarcinoma. The chemopreventive actions of statins, especially combined with cyclo-oxygenase inhibitors deserve further exploration.

Synergistic induction of apoptosis by sulindac and simvastatin in A549 human lung cancer cells via reactive oxygen species-dependent mitochondrial dysfunction

Prevention of lung cancer is more feasible and holds greater promise when different agents are used in combination to target multiple processes during carcinogenesis. The mechanisms by which non-steroidal anti-inflammatory drugs and statins inhibit cancer cell growth and induce apoptosis are not fully understood. This study was designed to investigate lung cancer chemoprevention through a mechanism-based approach using sulindac at low doses in combination with simvastatin. We found that sulindac-induced cytotoxicity was significantly enhanced in the presence of simvastatin. The combination of sulindac and simvastatin induced more extensive caspase-dependent apoptosis in A549 cells compared to that induced with either drug alone. The combination of sulindac and simvastatin also increased the loss of mitochondrial transmembrane potential (∆Ψm) and the cytosolic release of cytochrome c. In addition, ROS generation in cells treated with both sulindac and simvastatin was markedly increased compared to cells treated with either sulindac or simvastatin alone. The enhancement of ROS generation by sulindac and simvastatin was abrogated by pretreatment with NAC, which also prevented apoptosis and mitochondrial dysfunction induced by sulindac and simvastatin. These results suggest that sulindac and simvastatin-induced ROS generation in A549 lung cancer cells causes their accumulation in mitochondria, triggering the release of apoptogenic molecules from the mitochondria to the cytosol, and thus leading to caspase activation and cell death.

Interplay between SOX9, β-catenin and PPARγ activation in colorectal cancer

Colorectal carcinogenesis relies on loss of homeostasic mechanisms regulating cell proliferation, differentiation and survival. These cell processes have been reported to be influenced independently by transcription factors activated downstream of the Wnt pathway, such as SOX9 and β-catenin, and by the nuclear receptor PPARγ. The purpose of this study was to explore the expression levels and functional link between SOX9, β-catenin and PPARγ in the pathogenesis of colorectal cancer (CRC). We evaluated SOX9, β-catenin and PPARγ expression levels on human CRC specimens by qPCR and immunoblot detection. We tested the hypothesis that PPARγ activation might affect SOX9 and β-catenin expression using four colon cancer cell lines (CaCo2, SW480, HCT116, and HT29 cells). In CRC tissues SOX9 resulted up-regulated at both mRNA and protein levels when compared to matched normal mucosa, β-catenin resulted up-regulated at protein levels, while PPARG mRNA and PPARγ protein levels were down-regulated. A significant relationship was observed between high PPARG and SOX9 expression levels in the tumor tissue and female gender (p=0.005 and p=0.04, respectively), and between high SOX9 expression in the tumor tissue and age (p=0.04) and microsatellite instability (MSI), in particular with MSI-H (p=0.0002). Moreover, treatment with the synthetic PPARγ ligand rosiglitazone induced different changes of SOX9 and β-catenin expression and subcellular localization in the colon cancer cell lines examined. In conclusion, SOX9, β-catenin and PPARγ expression levels are deregulated in the CRC tissue, and in colon cancer cell lines ligand-dependent PPARγ activation unevenly influences SOX9 and β-catenin expression and subcellular localization, suggesting a variable mechanistic role in colon carcinogenesis.

Statin use is associated with a reduced incidence of colorectal adenomatous polyps

BACKGROUND

Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) have been shown to have potentially useful anticancer effects against colorectal cancers in experimental studies, but clinical studies have shown inconsistent results on colorectal cancer incidence. Most colorectal cancers are believed to develop through the polyp-cancer sequence. We hypothesized that statins may protect against the development of adenomatous polyps, and this may contribute to the apparent cancer-protective effects.

OBJECTIVE

This study aims to compare previous statin use in patients with newly diagnosed adenomatous polyps against a control group without polyps.

METHOD

A case-control study involving 264 patients attending for diagnostic colonoscopy at the Norfolk and Norwich University Hospital was used. Polyp cases were age and sex matched against controls with normal colonoscopies. Structured patient interviews and clinical notes were used to ascertain drug and risk factor. Logistic regression was used to compare statin exposure and correct for confounding factors.

RESULTS

There was a significant negative association between prior statin use and a diagnosis of adenomatous polyps [odds ratio (OR) = 0.40 (0.24-0.76)]. The association was significantly stronger with higher statin doses [≥40 mg simvastatin or equivalent; OR 0.33 (0.10-0.53)] or longer duration of use [>5 years; OR 0.36 (0.10-0.67)]. Statin use was negatively associated with both high- and low-risk polyps.

CONCLUSIONS

Statins may have a protective effect against the development of adenomatous polyps. The negative association between statin use and polyp incidence showed a significant dose and duration relationship.

Targeting FLIP and Mcl-1 using a combination of aspirin and sorafenib sensitizes colon cancer cells to TRAIL

The multikinase inhibitor sorafenib is highly effective against certain types of cancer in the clinic and prevents colon cancer cell proliferation in vitro. Non-steroidal anti-inflammatory drugs, such as acetylsalicylic acid (aspirin), have shown activity against colon cancer cells. The aims of this study were to determine whether the combination of aspirin with sorafenib has enhanced anti-proliferative effects and increases recombinant human tumour necrosis factor-related apoptosis-inducing ligand (rhTRAIL)-induced apoptosis in the human SW948, Lovo, Colo205, Colo320, Caco-2 and HCT116 colon cancer cell lines. In four cell lines, aspirin strongly stimulated the anti-proliferative effects of sorafenib (∼four-fold enhancement) by inducing cell cycle arrest. Furthermore, combining low doses of aspirin (≤ 5 mm) and sorafenib (≤ 2.5 µm) greatly sensitized TRAIL-sensitive and TRAIL-resistant colon cancer cells to rhTRAIL, much more potently than either drug combined with rhTRAIL. The increase in rhTRAIL sensitivity was due to inhibition of FLIP and Mcl-1 protein expression following aspirin and sorafenib co-treatment, as confirmed by knock-down studies. Next, the clinical relevance of targeting FLIP and Mcl-1 in colon cancer was examined. Using immunohistochemistry, we found that Mcl-1 expression was significantly increased in colon adenoma and carcinoma patient material compared to healthy colonic epithelium, similar to the enhanced FLIP expression we recently observed in colon cancer. These results underscore the potential of combining low doses of aspirin with sorafenib to inhibit proliferation and target the anti-apoptotic proteins FLIP and Mcl-1 in colon cancer cells.

Sub-toxic dose of apigenin sensitizes HepG2 cells to TRAIL through ERK-dependent up-regulation of TRAIL receptor DR5

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is regarded as a promising candidate for anticancer therapy due to its selective toxicity to cancer cells. Nevertheless, because of TRAIL resistance in some cancer cells, combined treatment with sensitizing agents is required to enhance the anticancer potential of TRAIL. In this study, we investigated the underlying mechanism of apigenin-induced sensitization of HepG2 cells to TRAIL-induced cell death. Synergistic induction of apoptosis by combination was confirmed by examining the typical morphology changes of apoptosis, PARP-cleavage, and activation of effector caspases. Z-VAD-fmk, a pan-caspase inhibitor, inhibited the enhanced cell death by combined treatment of apigenin and TRAIL, demonstrating that a caspase-dependent pathway is involved in apigenin/TRAIL-mediated apoptosis. In addition, we found that apigenin/ TRAIL co-treatment up-regulates DR5 cell surface expression. The synergistic induction of cell death by the apigenin/ TRAIL combination was significantly attenuated by DR5 blocking chimera antibody. Next, using pharmacological inhibitors, we found that ERK activation is involved in the induction of DR5 expression. Inhibition of ERK1/2 by U0126 significantly decreased the apigenin/TRAIL-induced DR5 expression and apoptosis. Taken together, our results indicate that apigenin can enhance the apoptotic effect of TRAIL via ERK-induced up-regulation of DR5.

Statin use is associated with a reduction in the incidence of esophageal adenocarcinoma: a case control study

The incidence of esophageal adenocarcinoma (EAC) is increasing significantly throughout the developed world. As yet, there are no proven chemopreventive strategies. In laboratory studies, aspirin, non-steroidal anti-inflammatory drugs and statins have promising chemopreventive actions. Several observational studies support a protective effect of aspirin and non-steroidal anti-inflammatory drugs, but there are only limited clinical data exploring the potential protective effect of statins. We conducted a case-control study examining aspirin and statin use in patients with EAC. Cancer cases were compared against age-sex-matched controls attending for diagnostic upper gastrointestinal endoscopy. Risk factor and drug exposure were established using standardized interviews. Logistic regression was used to compare statin exposure and correct for confounding factors. A total of 112 cases and 448 controls were enrolled. Statin use was associated with a significantly lower incidence of EAC (odds ratio 0.52, 95% confidence interval 0.27-0.92). Aspirin use was also associated with apparent protection against EAC (odds ratio 0.68, 95% confidence interval 0.28-0.92), and a significantly greater effect was seen with the combination of statin plus aspirin (odds ratio 0.27, 95% confidence interval 0.05-0.67). There was a significant trend for greater risk reduction with longer duration and higher doses of statin use. Simvastatin comprised the majority of statin use, but similar effects were seen with simvastatin and non-simvastatin agents. In this observational study, patients regularly using statins or aspirin had a lower incidence of EAC. Statins may have clinically useful effects in preventing the development of EAC.

Regular statin and aspirin use in patients with Barrett's oesophagus is associated with a reduced incidence of oesophageal adenocarcinoma

BACKGROUND

Oesophageal adenocarcinoma (OAC) has a poor prognosis, and chemoprevention is an attractive option to reduce the burden of the disease. Hydroxyl-methyl-CoA reductase inhibitors (statins) have been shown to exert potentially useful anticancer effects against OAC cell lines, but there are only limited clinical data examining the effects of statins on the incidence of OAC.

AIM

To examine the association between statin use and the incidence of OAC.

METHODS

We have carried out a case-control study comparing statin use between patients with an incident diagnosis of OAC and controls with nonprogressive Barrett's oesophagus. Eighty-five cancer cases were compared with 170 age-matched and sex-matched controls. Risk factors and drug exposure were established using standardized interviews. Logistic regression was used to compare statin exposure and correct for confounding factors.

RESULTS

Regular statin use was associated with a significantly lower incidence of OAC [uncorrected odds ratio (OR) 0.45, 95% confidence intervals 0.24-0.84)]. After correction for confounding variables including aspirin and NSAID use, statin use was still associated with a reduced incidence of OAC (OR 0.57, 0.28-0.94). Longer duration of statin use and higher doses were both associated with a significantly greater reduction in OAC. The combination of regular statin and aspirin use was associated with a significantly further reduced incidence of OAC (OR 0.31, 0.04-0.69).

CONCLUSION

In this observational case-control study, the regular use of statins was associated with a reduced incidence of OAC. The chemopreventative actions of statins, especially in conjunction with aspirin, deserve further study.

Statin use is associated with a reduced incidence of colorectal cancer: a colonoscopy-controlled case-control study

BACKGROUND

The aetiology of colorectal cancer (CRC) remains elusive in the majority of cases. There is experimental evidence to show that HMG-CoA reductase inhibitors (statins) may inhibit proliferation and induce cause apoptosis in CRC cells and although some clinical studies have suggested that statins may protect against the development of CRC, this has not been a consistent finding. Therefore we have examined any potential protective effects of statins by comparing statin use in patients with colorectal cancer against a control group.

METHODS

This was a case-control study examining statin use in symptomatic patients attending for diagnostic colonoscopy. Statin use was compared between patients with CRC and a control group, who had all had normal colonoscopy. Structured interviews and clinical records notes were used to determine drug exposure. Logistic regression was used to compare statin exposure and correct for confounding factors.

RESULTS

There was a significant inverse association between previous statin use and a diagnosis of CRC (OR = 0.43 (95% confidence interval 0.25 - 0.80), p<0.01). This inverse association was stronger with higher statin doses (OR = 0.19 (0.07 - 0.47), p<0.01) and greater duration of statin use (statin use >years: OR = 0.18 (0.06 - 0.55), p<0.01).

CONCLUSIONS

Statins use was associated with a protective effect against the development of CRC. This effect is associated with a significant dose and duration response. These findings need to be repeated in other observational studies before an interventional study can be considered.

Statins as modulators of colon cancer cells induced cytokine secretion by human PBMC

The study was designed to examine whether the hydrophilic statin - pravastatin and the hydrophobic statin - simvastatin affect colon cancer cell-induced cytokine secretion by peripheral blood mononuclear cells (PBMC). Statins were added to human colon cancer cells (HT-29 and RKO), or to PBMC incubated separately or jointly. The secretion of the pro-inflammatory cytokines IL-1β and IFNγ and that of the anti-inflammatory cytokines IL-1ra and IL-10 induced by cancer cells was decreased by simvastatin but not by pravastatin, whereas that of IL-6 was not affected by both drugs. Conditioned media from colon cancer cells incubated with either simvastatin or pravastatin induced stimulation of cytokine production by PBMC similar to that caused by conditioned media derived from cancer cells incubated without the drugs, suggesting that simvastatin acts directly on the interaction between cancer and PBM cells. Simvastatin, but not pravastatin, caused inhibition of both cancer cell proliferation. The results imply that simvastatin may affect inflammation-induced colon cancer proliferation via alteration of the equilibrium between pro- and anti-inflammatory cytokines.

TNF-related apoptosis-inducing ligand cooperates with NSAIDs via activated Wnt signalling in (pre)malignant colon cells

TNF-related apoptosis-inducing ligand (TRAIL) receptor agonistic agents and non-steroidal anti-inflammatory drugs (NSAIDs) are interesting agents for the chemoprevention and treatment of colorectal cancer. We investigated whether NSAIDs sensitize colon cancer and adenoma cell lines and ex vivo cultured human adenomas to recombinant human (rh)TRAIL. Involvement of the crucial Wnt signalling pathway in the sensitization of colon cancer cells was examined. Five colon cancer and two adenoma cell lines, human ex vivo adenomas and normal colonic epithelium were treated with aspirin or sulindac combined with rhTRAIL. Apoptosis levels, expression of intracellular proteins and TRAIL receptor membrane expression were assessed. Ls174T cells stably transfected with an inducible dominant negative TCF-4 (dnTCF-4) construct served to analyse the role of Wnt pathway activation. Both rhTRAIL-sensitive and -resistant colon cancer cell lines were strongly sensitized to rhTRAIL by aspirin (maximum enhancement ratio, 7.1). Remarkably, in adenoma cell lines sulindac enhanced rhTRAIL-induced apoptosis most effectively (maximum enhancement ratio, 2.5). Although membrane TRAIL receptor expression was not affected by NSAIDs, caspase-8 activation was enhanced by combinational treatment. Several proteins from different biological pathways were affected by NSAIDs, indicating complex mechanisms of sensitization. Elimination of TCF-4 completely blocked the sensitizing effect in colon cancer cells. In ex vivo adenomas the combination of sulindac and rhTRAIL increased apoptosis from 18.4% (sulindac) and 17.8% (rhTRAIL) to 28.0% (p = 0.003 and p = 0.005, respectively). It was concluded that NSAID-induced sensitization to rhTRAIL requires TCF-4 activity. Thus, the combination of TRAIL-receptor agonistic agents and NSAIDs is a potentially attractive treatment option for (pre)malignant tumours with constitutively active Wnt signalling, such as colorectal tumours.

Strategies for colon cancer prevention

Colorectal cancer (CRC) is common and is associated with a considerable mortality. Morbidity and thereby mortality can be reduced by using different prevention strategies such as lifestyle interventions and chemoprevention. Endoscopic surveillance of high-risk individuals and population-based endoscopic screening of average-risk individuals enables detection and removal of premalignant lesions (adenomas) as well as presymptomatic detection of cancer. Implementation of cancer detection tests such as fecal occult blood tests (FOBTs) is another strategy to reduce cancer mortality by early detection of CRC. Personalized management, based on estimates of the individual risk using information concerning environmental factors, lifestyle, family history, personality, social background and phenotype in combination with a variety of biomarkers such as genotype, will become more important as a strategy to optimize CRC prevention in the future.

The synergistic anticancer effect of troglitazone combined with aspirin causes cell cycle arrest and apoptosis in human lung cancer cells

Troglitazone (TGZ) is a synthetic thiazolidinedione drug belonging to a group of potent peroxisome proliferator-activated receptor gamma (PPAR gamma) agonists known to inhibit proliferation, alter cell cycle regulation, and induce apoptosis in various cancer cell types. TGZ is an oral anti-type II diabetes drug that can reverse insulin resistance. For more then 100 yr, aspirin, a nonselective cyclooxygenase (COX) inhibitor, has been successfully used as an anti-inflammatory drug. Recently, Aspirin (ASA) and some other nonsteroidal anti-inflammatory drugs (NSAIDs) have drawn much attention for their protective effects against colon cancer and cardiovascular disease; it has been observed that ASA's anti-tumor effect can be attributed to inhibition of cell cycle progression, induction of apoptosis, and inhibition of angiogenesis. In this report we demonstrate for the first time that, when administered in combination, TGZ and ASA can produce a strong synergistic effect in growth inhibition and G(1) arrest in lung cancer CL1-0 and A549 cells. Examination by colony formation assay revealed an even more profound synergy. In Western blot, combined TGZ and ASA also could downregulate Cdk2, E2F-1, cyclin B1, cyclin D3 protein, and the ratio of phospho-Rb/Rb. Importantly, apoptosis was synergistically induced by the combination treatment, as evidenced by caspase-3 activation and PARP cleavage. The involvement of PI3K/Akt inhibition and p27 upregulation, as well as hypophosphorylation of Rac1 at ser71, were demonstrated. Taken together, these results suggest that clinically achievable concentrations of TGZ and ASA used in combination may produce a strong anticancer synergy that warrants further investigation for its clinical applications.

Long-term use of statins and risk of colorectal cancer: a population-based study

OBJECTIVES

We conducted a population-based cohort study to determine the effect of long-term regular use of statins on the risk of colorectal cancer (CRC).

METHODS

Individuals who were dispensed statins regularly were identified from Manitoba's population-based prescription drug database and followed up until diagnosis of CRC, migration out of province, death, or December 2005. The incidence of CRC in this group was compared with that among individuals who were never dispensed statins. Stratified analysis was performed to determine the risk after 5 years of regular statin use. Multivariate Poisson regression models were used to adjust for potential confounding by age, sex, and history of diabetes, inflammatory bowel disease, coronary heart disease, lower gastrointestinal endoscopy, resective colorectal surgery, use of nonsteroidal anti-inflammatory drugs, hormone replacement therapy (among women), and median household income. The dose effect was evaluated in defined daily dose units.

RESULTS

In total, 35,739 individuals were dispensed statins regularly. In all, 10,287 (49% males; 51% females) long-term (>or=5 years) regular statin users were followed up for up to 5 additional years. In multivariate analysis, the incidence rate ratio (IRR) of CRC among those dispensed statins regularly compared with those who were never dispensed statins (n=377,532) was 1.13 (95% confidence interval (CI): 1.02-1.25). The CRC risk among the long-term regular statin users was similar to that for individuals never dispensed statins (IRR, 0.89; 95% CI: 0.70-1.13). A statistically nonsignificant risk reduction was observed among high-dose long-term regular statin users.

CONCLUSIONS

These findings suggest that long-term regular use of statins for the current clinical indications does not protect against CRC. The benefit of high-dose long-term statin use needs further evaluation.

Pilot study of oral anthocyanins for colorectal cancer chemoprevention

Naturally occurring anthocyanins possess colorectal cancer chemopreventive properties in rodent models. We investigated whether mirtocyan, an anthocyanin-rich standardized bilberry extract, causes pharmacodynamic changes consistent with chemopreventive efficacy and generates measurable levels of anthocyanins in blood, urine, and target tissue. Twenty-five colorectal cancer patients scheduled to undergo resection of primary tumor or liver metastases received mirtocyan 1.4, 2.8, or 5.6 grams (containing 0.5-2.0 grams anthocyanins) daily for 7 days before surgery. Bilberry anthocyanins were analyzed by high performance liquid chromatography (HPLC) with visible or mass spectrometric detection. Proliferation was determined by immunohistochemistry of Ki-67 in colorectal tumor. Concentrations of insulin-like growth factor (IGF)-I were measured in plasma. Mirtocyan anthocyanins and methyl and glucuronide metabolites were identified in plasma, colorectal tissue, and urine, but not in liver. Anthocyanin concentrations in plasma and urine were roughly dose-dependent, reaching approximately 179 ng/gram in tumor tissue at the highest dose. In tumor tissue from all patients on mirtocyan, proliferation was decreased by 7% compared with preintervention values. The low dose caused a small but nonsignificant reduction in circulating IGF-I concentrations. In conclusion, repeated administration of bilberry anthocyanins exerts pharmacodynamic effects and generates concentrations of anthocyanins in humans resembling those seen in Apc(Min) mice, a model of FAP adenomas sensitive to the chemopreventive properties of anthocyanins. Studies of doses containing <0.5 gram bilberry anthocyanins are necessary to adjudge whether they may be appropriate for development as colorectal cancer chemopreventive agents.

Statin Use and Cancer Risk: An Epidemiologic Review

While the beneficial effects of hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on cardiovascular disease are well established, much uncertainty remains about their effects on cancer. The statins inhibit the rate-limiting step in the mevalonate pathway, leading to reduced levels of cholesterol and other molecules of importance for critical cellular processes. A growing body of preclinical data indicates that statins may have antineoplastic properties, but some studies raise the possibility that statins may possess a carcinogenic potential. Clinical and observational studies of the association between statin use and cancer have been inconclusive with regard to any chemopreventive or therapeutic effect, but they do provide reassuring evidence that statins do not appear to be carcinogenic. The reasons for the varying results are unclear but they may relate to methodological issues. Additional studies, including Phase II randomized trials and epidemiological studies with accurate measures of statin use and comprehensive control for confounding factors, are needed to determine the potentially beneficially effects of statins on cancer development and progression.

Chemoprevention of colorectal cancer: feasibility in everyday practice?

Chemoprevention means the use of agents to prevent, delay, or reverse carcinogenesis. This review was designed to critically discuss the most promising agents in colorectal cancer (CRC) chemoprevention. Aspirin is the best studied chemopreventive agent for CRC. Optimal chemoprevention requires long-term use and high dose of aspirin that may increase the risk of gastrointestinal bleeding. Nonsteroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors may also be candidates for chemoprevention. The regular use of nonsteroidal anti-inflammatory drugs, however, causes adverse effects including gastrointestinal bleeding, and cyclooxygenase-2 inhibitors may increase the risk of cardiovascular events. In patients with ulcerative colitis 5-aminosalicylates reduce the risk of CRC and dysplasia. Ursodeoxycholic acid can reduce the risk of dysplasia or CRC in patients with primary sclerosing cholangitis and ulcerative colitis. Current data are insufficient to support the use of hormone replacement therapy to reduce the risk of CRC. Statins may have chemopreventive effects, but further investigation of their overall benefits in preventing CRC is warranted. Antioxidant supplements cannot prevent CRC. The usefulness of selenium, folate, calcium, and vitamin D awaits further evaluation. Chemoprevention cannot yet be accepted as standard medical practice. Use of chemopreventive agents cannot be a substitute for colorectal surveillance.

Colorectal cancer prevention in inflammatory bowel disease and the role of 5-aminosalicylic acid: a clinical review and update

A roundtable consensus meeting was held to consolidate current knowledge on the etiology of colorectal cancer in patients with inflammatory bowel disease and to review current strategies, both diagnostic and preventive, specifically addressing the role of 5-aminosalicylic acid. Specific topics that were addressed included: the epidemiology of colorectal cancer, including an assessment of risk factors and the impact of colonoscopy on colorectal cancer incidence and mortality; the origin and evolution of dysplasia nomenclature and the natural history of dysplasia; review of the experience of St. Mark's Hospital (London) as gleaned from its surveillance database; mechanisms by which 5-aminosalicylic acid is thought to exert a chemopreventive effect; the potential future role of 5-aminosalicylic acid in chemopreventive strategies; chemoprevention in familial adenomatous polyposis; and other future research directions. This article provides a comprehensive overview of the issues discussed and should act as a guide to shaping the design of future studies in this area.

Individual and joint use of statins and low-dose aspirin and risk of colorectal cancer: a population-based case-control study

Recent research has drawn attention to protective effects of statins on colorectal cancer (CRC) and possible joint effects with other drugs. Because statins are often administered in combination with low-dose aspirin for the prevention of cardiovascular disease, the aim of our study was to investigate individual and combined effects of statins and low-dose aspirin on CRC risk. We assessed use of statins and low-dose aspirin in 540 cases with histologically confirmed incident CRC and 614 control subjects in a population-based case-control study in Germany. Multiple logistic regression was used to estimate the impact of regular use of either low-dose aspirin or statins, and of both drugs combined on CRC risk. We found modest risk reduction of CRC for regular use of low-dose aspirin (adjusted odds ratio 0.77, 95% confidence interval 0.55-1.07) and a stronger association with regular use of statins (OR 0.65, 95% CI 0.43-0.99) or use of both drugs (OR 0.63, 95% CI 0.36-1.10). Combined use of low-dose aspirin and statins was associated with risk reduction by 62% after 5 or more years (OR 0.38, 95% CI 0.15-0.97). Combinational chemoprevention with low-dose aspirin and statins might provide stronger risk reduction than either of the single drugs after at least 5 years use, but confirmation is needed, preferably in prospective cohort studies and eventually by randomized controlled trials.

Inhibition of tumorigenesis in ApcMin/+ mice by a combination of (-)-epigallocatechin-3-gallate and fish oil

The effect of a combination of (-)-epigallocatechin-3-gallate (EGCG) with fish oil on intestinal tumorigenesis in Apc (Min/+) mice fed a high-fat diet was investigated in the present study. The combined treatment of EGCG and fish oil for 9 weeks reduced the tumor number by 53% as compared to controls while neither agent alone had a significant effect. Apoptosis was significantly increased in all treatment groups. beta-Catenin nuclear positivity in adenomas from the combination group was lower than control mice, implicating the modulation of Wnt signaling by the combination. Fish oil and the combination significantly reduced prostaglandin E 2 (PGE 2) levels in small intestinal tumors as compared to controls, suggesting modulation of aberrant arachidonic acid metabolism by fish oil. Akt phosphorylation in adenomas was significantly reduced in all treatment groups, which may have contributed to the observed increase in apoptosis. The results indicate that a combination of low doses of EGCG and fish oil can inhibit tumor multiplicity in Apc (Min/+) mice.

Expression of peroxisome proliferator-activated receptor-gamma in colon cancer: correlation with histopathological parameters, cell cycle-related molecules, and patients' survival

Peroxisome proliferator-activated receptor gamma (PPAR-gamma), a ligand-activated transcription factor, is a key regulator of adipogenic differentiation and glucose homeostasis. PPAR-gamma ligands have recently been demonstrated to affect proliferation and differentiation in cancer cells lines. The aim of the present work was to examine PPAR-gamma expression in colon cancer cases. PPAR-gamma expression was examined immunohistochemically in 86 colon cancer cases and was correlated with clinicopathological parameters, tumor proliferative capacity, cell cycle-related molecule expression, and patient survival. Positive PPAR-gamma immunostaining was prominent in 48 of 86 cases (56%). PPAR-gamma positivity was not correlated with Dukes' stage, histological grade of differentiation, lymph node and liver metastasis, venous invasion, tumor proliferative capacity, or patient survival. A statistically significant correlation was found between PPAR-gamma and the expression of cell cycle-related molecules pRb (P < 0.016), cyclin D1 (P <0.009), p16 (P<0.032), and p21 (P<0.033), while a positive trend for cyclin E was also noted (P<0.057). The pattern, intensity, and extent of PPAR-gamma expression in positive cases were not correlated with any of the examined variables. Our findings support evidence for participation of this protein in the biological mechanisms underlying carcinogenic evolution in the colon, also suggesting the importance of specific PPAR-gamma ligands as cell cycle modulators for a future therapeutic approach in colon cancer.

Prostaglandins and the colon cancer connection

Colorectal cancer is a leading cause of cancer-related deaths throughout the world. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the few agents that are known to inhibit colorectal tumorigenesis. The mechanisms that underlie this effect are poorly understood. Two recent studies have provided some significant insight. Castellone and colleagues showed that prostaglandin E2 modulates the beta-catenin signaling axis, a key pathway for colorectal tumorigenesis. Holla and colleagues showed that prostaglandin E2 might act via a nuclear receptor. These findings shed light on the mechanisms that underlie prostaglandin action, and provide a molecular framework for developing future treatments for colorectal cancer.