5-ASA affects cell cycle progression in colorectal cells by reversibly activating a replication checkpoint

Colorectal Cancer in Inflammatory Bowel Disease: A Review of the Role of Gut Microbiota and Bacterial Biofilms in Disease Pathogenesis

The risk of colorectal cancer [CRC] is increased in patients with inflammatory bowel disease [IBD], particularly in extensive ulcerative colitis [UC] and Crohn's colitis. Gut microbiota have been implicated in the pathogenesis of CRC via multiple mechanisms, including the release of reactive oxygen species and genotoxins, and induction of inflammation, as well as activation of the immune response. Gut microbiota can enhance their carcinogenic and proinflammatory properties by organising into biofilms, potentially making them more resistant to the host's immune system and to antibiotics. Colonic biofilms have the capacity to invade colonic tissue and accelerate tumorigenesis in tumour-prone models of mice. In the context of IBD, the prevalence of biofilms has been estimated to be up to 95%. Although the relationship between chronic inflammation and molecular mediators that contribute to IBD-associated CRC is well established, the role of gut microbiota and biofilms in this sequence is not fully understood. Because CRC can still arise in the absence of histological inflammation, there is a growing interest in identifying chemopreventive agents against IBD-associated CRC. Commonly used in the treatment of UC, 5-aminosalicylates have antimicrobial and anticarcinogenic properties that might have a role in the chemoprevention of CRC via the inhibition or modulation of carcinogenic gut microbiota and potentially of biofilm formation. Whether biologics and other IBD-targeted therapies can decrease the progression towards dysplasia and CRC, via mechanisms independent of inflammation, is still unknown. Further research is warranted to identify potential new microbial targets in therapy for chemoprevention of dysplasia and CRC in IBD.

Collagen hydrogel protects intestinal epithelial cells from indomethacin-induced damage: results of an in vitro experiment

INTRODUCTION. Indomethacin is a derivative of indoleacetic acid and has anti-inflammatory, analgesic and antipyretic effects. However, the results of numerous studies show that indomethacin, like many other nonsteroidal anti-inflammatory drugs (NSAIDs), have an inhibitory effect on the viability and functional activity of enterocytes. In this regard, the search for new ways to reduce the severity of side effects from the use of NSAIDs remains relevant. One of these approaches may be to enrich patients’ diets with non-drug biologically active compounds, including proteins. However, the effect of dietary proteins and biologically active peptides on NSAID-induced damage to the wall of the small intestine and stomach has not been sufficiently studied. AIM. To evaluate the ability of a collagen-containing dietary supplement to protect human duodenal epithelial cells (HuTu-80 line) from indomethacin-induced damage. MATERIALS AND METHODS. The composite collagen-containing hydrogel was provided by «FIRST ALIVE COLLAGEN» LLC (Russia) and is a registered dietary supplement. The work used a commercial culture of human skin fibroblast cells and human duodenal epithelial cells (line HuTu-80). The viability of intestinal cells and fibroblasts was assessed using light and fluorescence microscopy and flow cytometry methods. RESULTS AND DISCUSSION. It has been established that indomethacin inhibits cell growth, causes apoptosis and death of enterocytes, and also leads to the accumulation of cells in the S-phase, which indicates a disruption in the regulation of the cell cycle. It was revealed that collagen hydrogel prevents cell death caused by indomethacin and reduces the number of apoptotic cells in the population. The protective effect of collagen hydrogel is characterized by normalization of the cell cycle of enterocytes and restoration of their growth and proliferative activity. CONCLUSION. Thus, collagen hydrogel, in vitro, is able to reduce the pathogenic effect of indomethacin on human intestinal epithelial cells. The protective effect of collagen hydrogel is characterized by maintaining viability, inhibiting apoptotic processes, and maintaining cell cycle stability. The results obtained indicate the prospects of using a dietary supplement based on a composite collagen hydrogel as a prophylactic agent to reduce the risk of NSAID-associated gastrointestinal diseases. However, to confirm the therapeutic effectiveness of the dietary supplement, further research is necessary, both using experimental animal modeling of NSAID-associated diseases of the human gastrointestinal tract, and clinical studies.

Chemoprophylaxis of precancerous lesions in patients who are at a high risk of developing colorectal cancer (Review)

The diagnostics of colorectal cancer (CRC) and precancerous lesions in the colon is one of the most urgent matters to be considered for the modern protocols of complex examination, recommended for use from the age of 45 years, and including both instrumental and laboratory methods of research: Colonoscopy, CT colonography, flexible sigmoidoscopy, fecal occult blood test, fecal immunohistochemistry test and stool DNA test Nevertheless, the removal of those precancerous lesions does not solve the issue, and, apart from the regular endoscopic monitoring of patients who are at a high risk of developing CRC, the pharmacological treatment of certain key pathogenic mechanisms leading to the development of CRC is required. The present review to discusses the function of β-catenin in the transformation of precancerous colorectal lesions into CRC, when collaborating with PI3K/AKT/mTOR signaling pathway and other mechanisms. The existing methods for the early diagnostics and prevention of discovered anomalies are described and categorized. The analysis of the approaches to chemoprophylaxis of CRC, depending on the results of endoscopic, morphological and molecular-genetic tests, is presented.

Recyclable mesalamine-functionalized magnetic nanoparticles (mesalamine/GPTMS@SiO2@Fe3O4) for tandem Knoevenagel-Michael cyclocondensation: grinding technique for the synthesis of biologically active 2-amino-4H-benzo[b]pyran derivatives

In the present study, mesalamine-functionalized on magnetic nanoparticles (mesalamine/GPTMS@SiO2@Fe3O4) is fabricated as an efficient and magnetically recoverable nanocatalyst. The as-prepared nanocatalyst was successfully synthesized in three steps using a convenient and low-cost method via modification of the surface of Fe3O4 nanoparticles with silica and GPTMS, respectively, to afford GPTMS@SiO2@Fe3O4. Finally, treatment with mesalamine as a powerful antioxidant generates the final nanocatalyst. Then, its structure was characterized by FT-IR, SEM, TEM, EDX, XRD, BET, VSM, and TGA techniques. The average size was found to be approximately 38 nm using TEM analysis and the average crystallite size was found to be approximately 27.02 nm using XRD analysis. In particular, the synthesized nanocatalyst exhibited strong thermal stability up to 400 °C and high magnetization properties. The activity of the synthesized nanocatalyst was evaluated in the tandem Knoevenagel-Michael cyclocondensation of various aromatic aldehydes, dimedone and malononitrile under a dry grinding method at room temperature to provide biologically active 2-amino-4H-benzo[b]pyran derivatives products in a short time with good yields. The presented procedure offers several advantages including gram-scale synthesis, good green chemistry metrics (GCM), easy fabrication of the catalyst, atom economy (AE), no use of column chromatography, and avoiding the generation of toxic materials. Furthermore, the nanocatalyst can be reused for 8 cycles with no loss of performance by using an external magnet.

Chemoprevention of Colitis-Associated Dysplasia or Cancer in Inflammatory Bowel Disease

The association between inflammatory bowel disease and colorectal cancer is well known. Although the overall incidence of inflammatory bowel disease has declined recently, patients with this disease still have a 1.7-fold increased risk of colorectal cancer. The risk factors for developing colorectal cancer include extensive colitis, young age at diagnosis, disease duration, primary sclerosing cholangitis, chronic colonic mucosal inflammation, dysplasia lesion, and post-inflammatory polyps. In patients with inflammatory bowel disease, control of chronic inflammation and surveillance colonoscopies are important for the prevention of colorectal cancer. The 2017 guidelines from the European Crohn's and Colitis Organisation suggest that colonoscopies to screen for colorectal cancer should be performed when inflammatory bowel disease symptoms have lasted for 8 years. Current evidence supports the use of chemoprevention therapy with mesalamine to reduce the risk of colorectal cancer in patients with ulcerative colitis. Other compounds, including thiopurine, folic acid, statin, and tumor necrosis factor-α inhibitor, are controversial. Large surveillance cohort studies with longer follow-up duration are needed to evaluate the impact of drugs on colorectal cancer risks.

Promoting mechanism of serum amyloid a family expression in mouse intestinal epithelial cells

Serum amyloid A (SAA) is an acute phase inflammatory protein that we previously described as a robust biomarker of colorectal inflammation in patients with ulcerative colitis (UC) in clinical remission. However, what induces SAA expression in UC remains unclear. This study demonstrates that SAA is significantly expressed in the intestinal tract of UC mouse models when compared with C-reactive protein, another inflammatory biomarker. Moreover, interleukin-6 and tumor necrosis factor-α were found to promote SAA1 expression, as were Toll-like receptor ligands flagellin and lipopolysaccharide. Furthermore, results suggested that the nuclear factor-kappa B (NF-κB) pathway may be involved in the promotion of SAA1 expression by flagellin, which was inhibited by treatment with 5-aminosalicylic acid (5-ASA). Therefore, the flagellin/NF-κB/SAA1 axis may represent one of the mechanisms by which 5-ASA suppresses intestinal inflammation.

Sodium salicylate and 5-aminosalicylic acid synergistically inhibit the growth of human colon cancer cells and mouse intestinal polyp-derived cells

As colon cancer is one of the most common cancers in the world, practical prevention strategies for colon cancer are needed. Recently, treatment with aspirin and/or 5-aminosalicylic acid-related agents was reported to reduce the number of intestinal polyps in patients with familial adenomatous polyposis. To evaluate the mechanism of aspirin and 5-aminosalicylic acid for suppressing the colon polyp growth, single and combined effects of 5-aminosalicylic acid and sodium salicylate (metabolite of aspirin) were tested in the two human colon cancer cells with different cyclooxygenase-2 expression levels and intestinal polyp-derived cells from familial adenomatous polyposis model mouse. The combination induced cell-cycle arrest at the G1 phase along with inhibition of cell growth and colony-forming ability in these cells. The combination reduced cyclin D1 via proteasomal degradation and activated retinoblastoma protein. The combination inhibited the colony-forming ability of mouse colonic mucosa cells by about 50% and the colony-forming ability of mouse intestinal polyp-derived cells by about 90%. The expression level of cyclin D1 in colon mucosa cells was lower than that in intestinal polyp-derived cells. These results suggest that this combination may be more effective in inhibiting cell growth of intestinal polyps through cyclin D1 down-regulation.

Portulaca Oleracea L. Extract Ameliorates Intestinal Inflammation by Regulating Endoplasmic Reticulum Stress and Autophagy

Scope

To investigate the role of endoplasmic reticulum stress (ERS)‐induced autophagy in inflammatory bowel disease (IBD) and the intervention mechanism of Portulaca oleracea L. (POL) extract, a medicinal herb with anti‐inflammatory, antioxidant, immune‐regulating, and antitumor properties, in vitro and in vivo.

Methods and Results

An IL‐10‐deficient mouse model is used for in vivo experiments; a thapsigargin (Tg)‐stimulated ERS model of human colonic mucosal epithelial cells (HIECs) is used for in vitro experiments. The levels of ERS‐autophagy‐related proteins are examined by immunofluorescence and Western blot. Cellular ultrastructure is assessed with transmission electron microscopy.

POL extract promotes a healing effect on colitis by regulating ERS‐autophagy through the protein kinase R‐like endoplasmic reticulum kinase (PERK)‐eukaryotic initiation factor 2α (eIF2α)/Beclin1‐microtubule‐associated protein light chain 3II (LC3II) pathway.

Conclusion

Overall, the results of this study further confirm the anti‐inflammatory mechanism and protective effect of POL extract and provide a new research avenue for the clinical treatment of IBD.

Gut Organoid as a New Platform to Study Alginate and Chitosan Mediated PLGA Nanoparticles for Drug Delivery

Intestinal organoids can be used as an ex vivo epithelial model to study different drug delivery effects on epithelial cells’ luminal surface. In this study, the impact of surface charge on the delivery of 5-ASA loaded PLGA nanoparticles into the lumen of organoids was investigated. Alginate and chitosan were used to coat the nanoparticles and provide negative and positive charges on the particles, respectively. The organoid growth and viability were not affected by the presence of either alginate- or chitosan-coated nanoparticles. It was shown that nanoparticles could be transported from the serosal side of the organoids to the lumen as the dye gradually accumulated in the lumen by day 2–3 after adding the nanoparticles to the Matrigel. By day 5, the dye was eliminated from the lumen of the organoids. It was concluded that the positively charged nanoparticles were more readily transported across the epithelium into the lumen. It may be attributed to the affinity of epithelial cells to the positive charge. Thus, the organoid can be utilized as an appropriate model to mimic the functions of the intestinal epithelium and can be used as a model to evaluate the benefits of nanoparticle-based drug delivery.

5-Aminosalicylic acid inhibits stem cell function in human adenoma-derived cells: implications for chemoprophylaxis in colorectal tumorigenesis

Background

Most colorectal cancers (CRC) arise sporadically from precursor lesions: colonic polyps. Polyp resection prevents progression to CRC. Risk of future polyps is proportional to the number and size of polyps detected at screening, allowing identification of high-risk individuals who may benefit from effective chemoprophylaxis. We aimed to investigate the potential of 5-aminosalicylic acid (5-ASA), a medication used in the treatment of ulcerative colitis, as a possible preventative agent for sporadic CRC.

Methods

Human colorectal adenoma (PC/AA/C1, S/AN/C1 and S/RG/C2), transformed adenoma PC/AA/C1/SB10 and carcinoma cell lines (LS174T and SW620) were treated with 5-ASA. The effect on growth in two- and three-dimensional (3D) culture, β-catenin transcriptional activity and on cancer stemness properties of the cells were investigated.

Results

5-ASA was shown, in vitro, to inhibit the growth of adenoma cells and suppress β-catenin transcriptional activity. Downregulation of β-catenin was found to repress expression of stem cell marker LGR5 (leucine-rich G protein-coupled receptor-5) and functionally suppress stemness in human adenoma and carcinoma cells using 3D models of tumorigenesis.

Conclusions

5-ASA can suppress the cancer stem phenotype in adenoma-derived cells. Affordable and well-tolerated, 5-ASA is an outstanding candidate as a chemoprophylactic medication to reduce the risk of colorectal polyps and CRC in those at high risk.

Review article: withdrawal of 5-aminosalicylates in inflammatory bowel disease

BACKGROUND

5-aminosalicylates (5-ASA) are widely used in inflammatory bowel disease (IBD), but emerging evidence suggests that they may be safely withdrawn in significant subsets of patients. This is important to address: 5-ASA therapy accounts for up to 25% of total healthcare costs in ulcerative colitis (UC), while almost a third of patients with Crohn's disease (CD) receive long-term 5-ASA despite no clear evidence of benefit. Further, rationalising medication burden may improve overall adherence and outcome.

AIMS

To summarise the rationale for 5-ASA withdrawal, review the current evidence in both UC and CD and consider the data surrounding colorectal cancer (CRC) prevention, guiding an evidence-based withdrawal strategy.

METHODS

PubMed was searched to identify relevant studies. Only papers published in English were reviewed, with priority given to randomised clinical trials and meta-analyses.

RESULTS

For patients with UC, consideration of 5-ASA withdrawal should be made on a case-by-case basis, but it appears safest for those in deep remission without any of the following risk factors: younger age (<40 years), remission for less than 2 years, a history of multiple flares, extensive disease. 5-ASA withdrawal should also be considered in patients with UC escalated to biologic therapy who have achieved remission and in all patients with CD. Although 5-ASA therapy may have chemopreventive benefits for CRC, the cost-benefit ratio appears significant, and this indication is not justified by evidence in those who have achieved remission and are continuing therapy with other agents, or in those in sustained remission without a history of extensive disease.

CONCLUSIONS

Although the majority of patients with IBD receive 5-ASA during their disease course, safe withdrawal appears possible in many, with important implications for both health economics and patient experience. A number of unanswered questions, however, remain.

Epithelial transport in digestive diseases: mice, monolayers, and mechanisms

The transport of electrolytes and fluid by the intestinal epithelium is critical in health to maintain appropriate levels of fluidity of the intestinal contents. The transport mechanisms that underlie this physiological process are also subject to derangement in various digestive disease states, such as diarrheal illnesses. This article summarizes the 2019 Hans Ussing Lecture of the Epithelial Transport Group of the American Physiological Society and discusses some pathways by which intestinal transport is dysregulated, particularly in the setting of infection with the diarrheal pathogen, Salmonella, and in patients treated with small-molecule inhibitors of the tyrosine kinase activity of the epidermal growth factor receptor (EGFr-TKI). The burdensome diarrhea in patients infected with Salmonella may be attributable to decreased expression of the chloride-bicarbonate exchanger downregulated in adenoma (DRA) that participates in electroneutral NaCl absorption. This outcome is possibly secondary to increased epithelial proliferation and/or decreased epithelial differentiation that occurs following infection. Conversely, the diarrheal side effects of cancer treatment with EGFr-TKI may be related to the known ability of EGFr-associated signaling to reduce calcium-dependent chloride secretion. Overall, the findings described may suggest targets for therapeutic intervention in a variety of diarrheal disease states.

Role of Cellular Biomolecules in Screening, Diagnosis and Treatment of Colorectal Cancer

Background:

Prevention is the primary strategy to avoid the occurrence and mortality of colorectal cancer. Generally, the concentrations of tumor markers tested during the diagnosis and believed to assist the detection of disease in the early stages of cancer. Some of the biomarkers are also important during treatment and real-time monitoring of the progress of treatment.

Methods:

We considered a rationale search of key references from the database of peer-reviewed research and review literatures of colorectal cancer. The topic of search was focused on the novel methods and modern techniques of Screening, Diagnosis, and Treatment of colorectal cancer. The screened publications were critically analysed using a deductive content analysis and the matter was put in separate headings and sub headings.

Results:

It was found that endoscopic examination, early detection, and surgery are some of the common strategies to manage colorectal cancer because late stages are difficult to treat due to the high-cost requirement and fewer chances of survival. As far as chemotherapy is concerned, systemic chemotherapy has been shown to offer the maximum benefit to patients with cancer metastasis. Among different chemotherapy measures, primary colorectal cancer prevention agents involve pharmaceuticals, phytochemicals, and dietary supplements are some of the standard options.

Conclusion:

In this review article, we have provided a comprehensive analysis of different biomarkers for the detection of colorectal cancer as well as different formulations developed for efficient treatment of the disease. The use of dietary supplements, the combinatorial approach, and nanotechnology-based strategies for colorectal cancer diagnosis and treatment are some of the recent and modern methods of cancer management.

Mesalamine and azathioprine modulate junctional complexes and restore epithelial barrier function in intestinal inflammation

Disruption of mucosal structure and barrier function contribute to the pathogenesis of inflammatory bowel disease (IBD). Efficacy of therapy in IBD is based on endoscopic mucosal healing, which occurs by a dynamic interplay of epithelial cell regeneration, migration and differentiation. Both mesalamine (5-ASA) and azathioprine (AZTP) promote this process through mechanisms not clearly understood. We examined molecular pathways implicated in epithelial barrier function that were altered by 5-ASA and AZTP. Paracellular permeability induced by inflammatory mediators was mitigated by both compounds through restoration of cellular anchoring complexes. 5-ASA and AZTP induced rearrangement and membranous localization of junctional proteins and modulated genes involved in tight junctions. Intestinal organoids from wildtype-mice treated with TNF-α and IL-10- deficient-mice displayed impaired epithelial barrier with loss of membranous E-cadherin and reduced Desmoglein-2 expression. These effects were counteracted by 5-ASA and AZTP. Unlike AZTP that exhibited antiproliferative effects, 5-ASA promoted wound healing in colon epithelial cells. Both affected cellular senescence, cell cycle distribution and restricted cells in G1 or S phase without inducing apoptosis. This study provides mechanistic evidence that molecular actions of 5-ASA and AZTP on intestinal epithelia are fundamental in the resolution of barrier dysfunction.

Identification of PMN-released mutagenic factors in a co-culture model for colitis-associated cancer

Microsatellite instability (MSI) is present in ulcerative colitis (UC) and colitis-associated colorectal cancers (CAC). Certain factors released by polymorphonuclear cells (PMNs) may drive mucosal frameshift mutations resulting in MSI and cancer. Here, we applied a co-culture system with PMNs and colon epithelial cells to identify such culprit factors. Subjecting HCT116 + chr3 and human colonic epithelial cells (HCEC)-1CT MSI-reporter cell lines harboring mono-, di- or tetranucleotide DNA repeats linked to enhanced green fluorescent protein (EGFP) to activated PMNs induced frameshift mutations within all repeats, as quantified by flow cytometry. Activated PMNs released superoxide and hydrogen peroxide (H₂O₂), as measured by lucigenin-amplified chemiluminescence and fluorometry, respectively. Catalase, which scavenges H₂O₂, reduced such PMN-induced MSI. The NADPH-oxidase inhibitor apocynin, which blocks the oxidative burst in PMNs, similarly inhibited PMN-induced MSI. A bead-based multiplex assay revealed that PMNs release a wide range of cytokines such as interleukin (IL)-8, IL-6 and tumor necrosis factor-α (TNF-α). In vitro, these cytokines increased MSI in colon epithelial cells, and the Janus kinase (JAK) inhibitor tofacitinib abolished IL-6-induced or PMN-induced MSI. Intracellular reactive oxygen species (ROS) formation, as measured by 2’,7’–dichlorofluorescein diacetate (DCFDA) assay, was induced upon cytokine treatment. DNA oxidation upon IL-6 was present, as detected by formamidopyrimidine glycosylase (FPG)-modified comet assay. In conclusion, activated PMNs induce frameshift mutations in colon epithelial cells resulting in MSI. Both oxidative burst with release of ROS and PMN-secreted cytokines, such as IL-8, IL-6 or TNF-α, contribute to MSI. ROS scavengers and/or specific inhibitors of cytokine signaling may delay or prevent cancer development in the setting of colitis.

DNA damage response and repair in colorectal cancer: Defects, regulation and therapeutic implications

DNA damage response, a key factor involved in maintaining genome integrity and stability, consists of several kinase-dependent signaling pathways, which sense and transduce DNA damage signal. The severity of damage appears to determine DNA damage responses, which can include cell cycle arrest, damage repair and apoptosis. A number of recent studies have demonstrated that defection in signaling through this network is thought to be an underlying mechanism behind the development and progression of various types of human malignancies, including colorectal cancer. In this review, colorectal cancer and its molecular pathology as well as DNA damage response is briefly introduced. Finally, the involvement of key components of this network in the initiation/progression, prognosis, response to treatment and development of drug resistance is comprehensively discussed.

KLF4 Mediates the Effect of 5-ASA on the β-Catenin Pathway in Colon Cancer Cells

Mesalazine (5-ASA) is an aminosalicylate anti-inflammatory drug capable of inducing μ-protocadherin, a protein expressed by colorectal epithelial cells that is downregulated upon malignant transformation. Treatment with 5-ASA restores μ-protocadherin expression and promotes the sequestration of β-catenin to the plasma membrane. Here, we show that 5-ASA-induced μ-protocadherin expression is directly regulated by the KLF4 transcription factor. In addition, we suggest the existence of a dual mechanism whereby 5-ASA-mediated β-catenin inhibition is caused by μ-protocadherin-dependent sequestration of β-catenin to the plasma membrane and by the direct binding of KLF4 to β-catenin. In addition, we found that 5-ASA treatment suppresses the expression of miR-130a and miR-135b, which target KLF4 mRNA, raising the possibility that this mechanism is involved in the increased expression of KLF4 induced by 5-ASA. Cancer Prev Res; 11(8); 503-10. ©2018 AACR.

Systematic review with meta-analysis: use of 5-aminosalicylates and risk of colorectal neoplasia in patients with inflammatory bowel disease

BACKGROUND

The relationship of 5-aminosalicylates' use with the risk of colorectal neoplasia in patients with inflammatory bowel disease (IBD) has been the focus of a growing body of research.

AIM

To investigate this association through an updated meta-analysis of observational studies.

METHODS

PubMed, Scopus and major conference proceedings were searched up to December 2016. The identified studies were evaluated for publication bias and heterogeneity. Pooled relative risk (RR) estimates were calculated using random-effect models. Detailed subgroup analyses were performed. The GRADE approach was used to assess the quality of evidence.

RESULTS

Thirty-one independent observational studies including 2137 cases of colorectal neoplasia (of which 76% were cancers) were incorporated. Between-study heterogeneity was moderate, while strong suspicion of small-study effects was raised. The overall analysis revealed a protective association between 5-aminosalicylates' use and colorectal neoplasia (RR = 0.57, 95% CI: 0.45-0.71). When the analysis was stratified according to study design and setting, the association was significant in cohort (RR = 0.65, 95% CI: 0.43-0.99; n = 10) and case-control studies (RR = 0.53, 95% CI: 0.40-0.70; n = 21), population-based (RR = 0.70, 95% CI: 0.52-0.94; n = 12) and hospital-based studies (RR = 0.46, 95% CI: 0.34-0.61; n = 19). Exposure to 5-aminosalicylates was protective against cancer (RR = 0.58, 95% CI: 0.45-0.74) and dysplasia (RR = 0.54, 95% CI: 0.35-0.84). The reduction in colorectal neoplasia risk was strong in ulcerative colitis (RR = 0.50, 95% CI: 0.38-0.64), but nonsignificant in Crohn's disease (RR = 0.76, 95% CI: 0.43-1.33). Mesalazine (mesalamine) use was protective (RR = 0.70, 95% CI: 0.51-0.94) with evidence of a dose-effect. The effect of sulfasalazine was marginally nonsignificant (RR = 0.72, 95% CI: 0.51-1.01).

CONCLUSIONS

Our findings support a potential chemopreventive role of 5-aminosalicylates in IBD. Further, high-quality prospective research is warranted.

Chemoprevention of colorectal cancer in inflammatory bowel disease

INTRODUCTION

Patients with inflammatory bowel disease are at an increased risk of colorectal cancer when compared to the general population. Chronic inflammation is thought to be the underlying cause, and medications that reduce inflammation have the potential to reduce the risk of colorectal cancer. Areas covered: After conducting a PubMed search for relevant literature, we examined several classes of medications that have been studied as potential chemopreventive agents. These include 5-aminosalicylates, thiopurines, tumor necrosis factor antagonists, ursodeoxycholic acid, NSAIDs, and statins. Expert commentary: While each class of medications has some data to support its use in chemoprevention, the majority of the evidence in each case argues against the routine use of these medications solely for a chemopreventive benefit.

Mesalazine and thymoquinone attenuate intestinal tumour development in Msh2(loxP/loxP) Villin-Cre mice

OBJECTIVE

Lynch syndrome is caused by germline mutations in DNA mismatch repair genes leading to microsatellite instability (MSI) and colorectal cancer. Mesalazine, commonly used for the treatment of UC, reduces MSI in vitro. Here, we tested natural compounds for such activity and applied mesalazine and thymoquinone in a Msh2(loxP/loxP) Villin-Cre mouse model for Lynch syndrome.

DESIGN

Flow cytometry was used for quantitation of mutation rates at a CA13 microsatellite in human colon cancer (HCT116) cells that had been stably transfected with pIREShyg2-enhanced green fluorescent protein/CA13, a reporter for frameshift mutations. Mice were treated for 43 weeks with mesalazine, thymoquinone or control chow. Intestines were analysed for tumour incidence, tumour multiplicity and size. MSI testing was performed from microdissected normal intestinal or tumour tissue, compared with mouse tails and quantified by the number of mutations per marker (NMPM).

RESULTS

Besides mesalazine, thymoquinone significantly improved replication fidelity at 1.25 and 2.5 µM in HCT116 cells. In Msh2(loxP/loxP) Villin-Cre mice, tumour incidence was reduced by mesalazine from 94% to 69% (p=0.04) and to 56% (p=0.003) by thymoquinone. The mean number of tumours was reduced from 3.1 to 1.4 by mesalazine (p=0.004) and to 1.1 by thymoquinone (p<0.001). Interestingly, MSI was reduced in normal intestinal tissue from 1.5 to 1.2 NMPM (p=0.006) and to 1.1 NMPM (p=0.01) by mesalazine and thymoquinone, respectively. Thymoquinone, but not mesalazine, reduced MSI in tumours.

CONCLUSIONS

Mesalazine and thymoquinone reduce tumour incidence and multiplicity in Msh2(loxP/loxP) Villin-Cre mice by reduction of MSI independent of a functional mismatch repair system. Both substances are candidate compounds for chemoprevention in Lynch syndrome mutation carriers.

PAK1 promotes intestinal tumor initiation

p21-activated kinase 1 (PAK1) is a serine/threonine kinase that is overexpressed in colorectal cancer. PAK1 is a target of mesalamine [5-aminosylicylic acid (5-ASA)], a common drug for the treatment of ulcerative colitis with prospective chemopreventive properties. Here, we investigated whether PAK1 deletion impedes tumorigenesis in murine intestinal cancer models. Ten-week-old APC(min) or APC(min)/PAK1(-/-) mice were monitored for 8 weeks, euthanized, and assessed for tumor number and size. Six- to 8-week-old PAK1(-/-) and wild-type (WT) mice received one 10 mg/kg intraperitoneal injection of azoxymethane (AOM) and four cycles of 1.7% dextran sodium sulfate (DSS) for 4 days followed by 14 days of regular water. Mice also received 5-ASA via diet. Tumor incidence and size was assessed via colonoscopy and pathology. Molecular targets of PAK1 and 5-ASA were evaluated via immunohistochemistry (IHC) in both models. PAK1 deletion reduced tumor multiplicity and tumor burden but did not alter average tumor size in APC(min) mice. IHC revealed that PAK1 deletion reduced p-AKT, β-catenin, and c-Myc expression in APC(min) adenomas. Colonoscopy and pathologic analysis revealed that PAK1 deletion reduced tumor multiplicity without affecting tumor size in AOM/DSS-treated mice. 5-ASA treatment and PAK1 deletion impeded tumor multiplicity and dysplastic lesions in AOM/DSS mice. IHC further revealed that 5-ASA blocked β-catenin signaling via inhibition of PAK1/p-AKT. These data indicate that PAK1 contributes to initiation of intestinal carcinogenesis.

Overexpression of PAK1 promotes cell survival in inflammatory bowel diseases and colitis-associated cancer

BACKGROUND

Chronic gut inflammation predisposes to the development of colorectal cancer and increased mortality. Use of mesalamine (5-ASA) in the treatment of ulcerative colitis modulates the risk of neoplastic progression. p21 activated kinase 1 (PAK1) mediates 5-ASA activity by orchestrating MAPK signaling, Wnt-β catenin pathway, and cell adhesion; all implicated in the colon carcinogenesis. We evaluated the role of PAK1 in IBD and in colitis-associated cancer (CAC).

METHODS AND RESULTS

PAK1 expression was scored by immunohistochemistry in human samples from IBD, CAC, and in normal mucosa. Compared with controls, a higher PAK1 expression was detected in IBD which further increased in CAC. The consequence of PAK1 overexpression was investigated using normal diploid colon epithelial cells (HCEC-1CT), which showed higher proliferation and decreased apoptosis on overexpression of PAK1. Analysis of IBD and CAC samples showed activation of AKT (p-AKT). However, mTOR pathway was activated in IBD but not in CAC. Treatment of cells with specific inhibitors (PD98059/LY294002/rapamycin) of growth signaling pathways (MEK/PI3K/mTOR) demonstrated that in HCEC-1CT, PAK1 expression is regulated by MEK, PI3K, and mTOR. In colorectal cancer cell lines, PAK1, and beta-catenin expression correlated and inhibition of PAK1 and addition of 5-ASA elicited similar molecular affects by reducing ERK and AKT activation. Moreover, 5-ASA disrupted PAK1 interaction and colocalization with β-catenin.

CONCLUSIONS

Our data indicate that (1) PAK1 is upregulated in IBD and CAC (2) PAK1 overexpression is associated with activation of PI3K-AKT/mTOR prosurvival pathways in IBD.

Inflammatory bowel disease and risk of cholangiocarcinoma: evidence from a meta-analysis of population-based studies

OBJECTIVE

Patients with inflammatory bowel disease (IBD) have an increased risk of extra-intestinal cancer, whereas its impact on cholangiocarcinoma (CC) remains unknown. The aim of this study was to obtain a reliable estimate of the risk of CC in IBD patients through a meta-analysis of clinical observational studies.

METHODS

Relevant studies were retrieved by searching PUBMED, EMBASE and Web of Science Databases up to Dec 2013. Four population-based case-control and two cohort studies with IBD were identified. Summary relative risk (RR) and its corresponding 95% confidence interval (CI) were calculated using a random-effects model. Potential sources of heterogeneity were detected using subgroup analyses.

RESULTS

The pooled risk estimate indicated IBD patients were at increased risk of CC (RR = 2.63, 95%CI = 1.47-4.72). Moreover, the increased risk of CC was also associated with Crohn's disease (RR = 2.69, 95%CI = 1.59-4.55) and ulcerative colitis (RR = 3.40, 95%CI = 2.50-4.62). In addition, site-specific analyses revealed that IBD patients had an increased risk of intrahepatic CC (ICC) (RR = 2.61, 95%CI = 1.72-3.95) and extrahepatic CC (ECC) (RR = 1.47, 95%CI = 1.10- 1.97).

CONCLUSIONS

This study suggests the risk of CC is significantly increased among IBD patients, especially in ICC cases. Further studies are warranted to enable definite conclusions to be drawn.

Chemoprevention of colorectal cancer

Colorectal cancer has become one of the most prevalent malignant diseases for both men and women. Patients with inflammatory bowel diseases or certain inherited cancer syndromes are at high risk of developing colorectal cancer and have naturally the highest need for cancer prevention. In familial adenomatous polyposis (FAP) and Lynch syndrome, most of the underlying germline mutations can be detected by DNA sequencing, and medical counselling of affected individuals involves both surveillance tests and chemopreventive measures. However, as the mechanisms leading to colorectal cancer differ in these high-risk groups, the molecular action of chemopreventive drugs needs to be adjusted to the certain pathway of carcinogenesis. In the last decades, a number of drugs have been tested, including sulindac, aspirin, celecoxib, and mesalazine, but some of them are still controversially discussed. This review summarizes the advances and current standards of colorectal cancer prevention in patients with inflammatory bowel disease, FAP and Lynch syndrome.

DUOX2 and DUOXA2 form the predominant enzyme system capable of producing the reactive oxygen species H2O2 in active ulcerative colitis and are modulated by 5-aminosalicylic acid

BACKGROUND

NADPH oxidase-derived reactive oxygen species, such as H2O2, are part of the intestinal innate immune system but may drive carcinogenesis through DNA damage. We sought to identify the predominant enzyme system capable of producing H2O2 in active ulcerative colitis and assess whether it is affected by 5-aminosalicylic acid (5-ASA).

METHODS

We studied human mucosal biopsies by expression arrays, quantitative real-time polymerase chain reaction for NADPH oxidase family members, in situ hybridization (DUOX2 and DUOXA2) and immunofluorescence for DUOX, 8-OHdG (DNA damage), and γH2AX (DNA damage response) and sought effects of 5-ASA on ex vivo cultured biopsies and cultured rectal cancer cells.

RESULTS

DUOX2 with maturation partner DUOXA2 forms the predominant system for H2O2 production in human colon and is upregulated in active colitis. DUOX2 in situ is exclusively epithelial, varies between and within individual crypts, and increases near inflammation. 8-OHdG and γH2AX were observed in damaged crypt epithelium. 5-ASA upregulated DUOX2 and DUOXA2 levels in the setting of active versus quiescent disease and altered DUOX2 expression in cultured biopsies. Ingenuity pathway analysis confirmed that inflammation status and 5-ASA increase expression of DUOX2 and DUOXA2. An epithelial cell model confirmed that cultured cancer cells expressed DUOX protein and produced H2O2 in response to hypoxia and 5-ASA exposure.

CONCLUSIONS

Both DUOX2 and DUOXA2 expression are involved specifically in inflammation and are regulated on a crypt-by-crypt basis in ulcerative colitis tissues. Synergy between inflammation, hypoxia, and 5-ASA to increase H2O2 production could explain how 5-ASA supports innate defense, although potentially increasing the burden of DNA damage.

5-Aminosalicylic acid and chemoprevention: does it work?

5-Aminosalicylic acid (5-ASA)-containing drugs are the mainstay of therapy in inflammatory bowel disease (IBD). Intestinal inflammation is the main risk factor for colorectal cancer (CRC) in IBD. Hence, all drugs that are able to induce and maintain mucosal healing (MH) may prevent CRC risk in IBD. In patients with mild to moderate ulcerative colitis (UC), a recent systematic review of 5-ASA trials demonstrated that MH was achieved in nearly 50% of patients. A systematic review including 48 studies linked 5-ASA chemopreventive properties to five distinct pathways: cell cycle progression, scavenging of reactive oxygen- or nitrogen-derived metabolites, TNF-α/TGF-ss signaling, WNT/β-catenin signaling and antibacterial properties. Therefore, in addition to their overall anti-inflammatory activity on the intestinal mucosa, 5-ASA compounds have specific effects on colorectal carcinogenesis at the molecular level. In 2005, a landmark meta-analysis of observational studies found a protective association between 5-ASA and CRC or a combined end point of CRC/dysplasia in UC patients. More recently, a meta-analysis failed to identify a protective effect of 5-ASA on CRC risk in non-referral populations, but in a separate analysis of 9 clinic-based studies, the pooled odds ratio was 0.58 (95% confidence interval: 0.45-0.75), further highlighting the chemopreventive effect of 5-ASA on CRC risk. In conclusion, 5-ASA therapy may reduce CRC risk by healing the mucosa of UC patients and via specific mechanisms of action at the molecular level. Conducting a clinical trial providing the best level of evidence by comparing UC patients receiving 5-ASA treatment versus those included in a placebo arm would be unethical.

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.

Antioxidant properties of mesalamine in colitis inhibit phosphoinositide 3-kinase signaling in progenitor cells

BACKGROUND

Mesalamine, 5-aminosalicylic acid (5-ASA), is a potent antioxidant and is known to enhance peroxisome proliferator-activated receptor γ activity in the intestine. Our previous studies suggested reduced Phosphoinositide 3-Kinase (PI3K)/β-catenin signaling as a mechanism for 5-ASA chemoprevention in chronic ulcerative colitis (CUC). We now hypothesize that 5-ASA mediates changes in intestinal epithelial cell (IEC) reactive oxygen species during colitis to affect phosphatase and tensin homolog (PTEN), PI3K, and β-catenin signaling.

METHODS

Here, we examined effects of 5-ASA on oxidant-induced cell signaling pathways in HT-29 cells, IECs from mice, and biopsy tissue from control and CUC patients. Samples were selected to control for inflammation between untreated and 5-ASA-treated CUC patients.

RESULTS

Direct evaluation of IEC in H2O2-stimulated whole colonic crypts indicated that 5-ASA reduces reactive oxygen species levels in lower crypt IECs where long-lived progenitor cells reside. Analysis of biopsies from patient samples revealed that 5-ASA increases expression of the antioxidant catalase in CUC patients. Also, 5-ASA increased nuclear peroxisome proliferator-activated receptor γ protein and target gene expression. Data showed 5-ASA-induced peroxisome proliferator-activated receptor γ DNA binding to the PTEN promoter (chromatin immunoprecipitation) and reduced both phosphorylated and oxidized (inactive) PTEN protein levels. Analysis of patient samples revealed 5-ASA that also reduced levels of active phosphorylated Akt in inflamed colitis tissue. Reduced PI3K/Akt signaling and expression of β-catenin target genes in 5-ASA-treated CUC patients additionally suggests enhanced PTEN activity as well.

CONCLUSIONS

Therefore, 5-ASA reduces CUC-induced reactive oxygen species in colonic progenitor cells and enhances PTEN activity, thus attenuating PI3K/Akt signaling. These data suggest that the antioxidant properties of 5-ASA may be the predominant mechanism for 5-ASA chemoprevention.

Mesalamine modulates intercellular adhesion through inhibition of p-21 activated kinase-1

Mesalamine (5-ASA) is widely used for the treatment of ulcerative colitis, a remitting condition characterized by chronic inflammation of the colon. Knowledge about the molecular and cellular targets of 5-ASA is limited and a clear understanding of its activity in intestinal homeostasis and interference with neoplastic progression is lacking. We sought to identify molecular pathways interfered by 5-ASA, using CRC cell lines with different genetic background. Microarray was performed for gene expression profile of 5-ASA-treated and untreated cells (HCT116 and HT29). Filtering and analysis of data identified three oncogenic pathways interfered by 5-ASA: MAPK/ERK pathway, cell adhesion and β-catenin/Wnt signaling. PAK1 emerged as a consensus target of 5-ASA, orchestrating these pathways. We further investigated the effect of 5-ASA on cell adhesion. 5-ASA increased cell adhesion which was measured by cell adhesion assay and transcellular-resistance measurement. Moreover, 5-ASA treatment restored membranous expression of adhesion molecules E-cadherin and β-catenin. Role of PAK1 as a mediator of mesalamine activity was validated in vitro and in vivo. Inhibition of PAK1 by RNA interference also increased cell adhesion. PAK1 expression was elevated in APC^min polyps and 5-ASA treatment reduced its expression. Our data demonstrates novel pharmacological mechanism of mesalamine in modulation of cell adhesion and role of PAK1 in APC^min polyposis. We propose that inhibition of PAK1 expression by 5-ASA can impede with neoplastic progression in colorectal carcinogenesis. The mechanism of PAK1 inhibition and induction of membranous translocation of adhesion proteins by 5-ASA might be independent of its known anti-inflammatory action.

Colorectal cancer chemoprevention by mesalazine and its derivatives

Patients with inflammatory bowel disease (IBD) face an increased lifetime risk of developing colorectal cancer (CRC). Independent factors associated with increased risk include long disease duration, extensive colonic involvement, young age at onset of IBD, severity of inflammation, primary sclerosing cholangitis, backwash ileitis, and a family history of CRC, thus emphasising the role of intestinal inflammation as an underlying mechanism. This notion is also supported by the demonstration that the use of certain drugs used to attenuate the ongoing mucosal inflammation, such as mesalazine, seems to associate with a reduced incidence of colitis-associated CRC. In the last decade, work from many laboratories has contributed to delineate the mechanisms by which mesalazine alters CRC cell behaviour. In this paper, we review the available experimental data supporting the ability of mesalazine and its derivatives to interfere with intracellular signals involved in CRC cell growth.

Acute sensitization of colon cancer cells to inflammatory cytokines by prophase arrest

Understanding how colon cancer cells survive within the inflammatory milieu of a tumor, and developing approaches that increase their sensitivity to inflammatory cytokines, may ultimately lead to novel approaches for colon cancer therapy and prevention. Analysis of a number of chemopreventive and therapeutic agents reveal that HDAC inhibitors are particularly adept at sensitizing colon cancer cells TNF or TRAIL mediated apoptosis. In vivo data are consistent with an interaction between SAHA and TNF in inducing apoptosis, as AOM-induced colon tumors express elevated levels of TNF and are more sensitive to SAHA administration. Cell cycle analysis and time-lapse imaging indicated a close correspondence between SAHA-induced prophase arrest and TNF or TRAIL-induced apoptosis. Prophase arrest induced by the Aurora kinase inhibitor VX680 likewise sensitized cells to TNF and TRAIL, with siRNA analysis pointing to Aurora kinase A (and not Aurora kinase B) as being the relevant target for this sensitization. We propose that agents that promote prophase arrest may help sensitize cancer cells to TNF and other inflammatory cytokines. We also discuss how circumvention of an early mitotic checkpoint may facilitate cancer cell survival in the inflammatory micro-environment of the tumor.

Aminosalicylates

Aminosalicylates are the most common drugs for the primary treatment of inflammatory bowel disease. Various pro-drugs and formulations were developed in order to improve pharmacological profiles, optimize bioavailability and to gain highest efficacy in the treatment of ulcerative colitis (UC) and Crohn's disease. In vitro studies have greatly contributed to the understanding of the molecular actions in vivo and clinical studies have proven aminosalicylates to be effective and safe. This review summarizes the current knowledge on the molecular, pharmacological and clinical properties of aminosalicylates with respect to chemoprevention for UC-associated colorectal cancer.

Pathogenesis and biomarkers of carcinogenesis in ulcerative colitis

One of the most serious complications of ulcerative colitis is the development of colorectal cancer. Screening patients with ulcerative colitis by standard histological examination of random intestinal biopsy samples might be inefficient as a method of cancer surveillance. This Review focuses on the current understanding of the pathogenesis of ulcerative colitis-associated colorectal cancer and how this knowledge can be transferred into patient management to assist clinicians and pathologists in identifying patients with ulcerative colitis who have an increased risk of colorectal cancer. Inflammation-driven mechanisms of DNA damage, including the generation and effects of reactive oxygen species, microsatellite instability, telomere shortening and chromosomal instability, are reviewed, as are the molecular responses to genomic stress. We also discuss how these mechanisms can be translated into usable biomarkers. Although progress has been made in the understanding of inflammation-driven carcinogenesis, markers based on these findings possess insufficient sensitivity or specificity to be usable as reliable biomarkers for risk of colorectal cancer development in patients with ulcerative colitis. However, screening for mutations in p53 could be relevant in the surveillance of patients with ulcerative colitis. Several other new biomarkers, including senescence markers and α-methylacyl-CoA-racemase, might be future candidates for preneoplastic markers in ulcerative colitis.

Role of organic anion-transporting polypeptides for cellular mesalazine (5-aminosalicylic acid) uptake

The therapeutic effects and metabolism of mesalazine (5-aminosalicylic acid) in patients with inflammatory bowel disease require intracellular accumulation of the drug in intestinal epithelial cells and hepatocytes. The molecular mechanisms of mesalazine uptake into cells have not been characterized so far. Using human embryonic kidney cells stably expressing uptake transporters of the organic anion-transporting polypeptide (OATP) family, which are expressed in human intestine and/or liver, we found that mesalazine uptake is mediated by OATP1B1, OATP1B3, and OATP2B1 but not by OATP1A2 and OATP4A1. Moreover, genetic variations (*1b, *5, *15) in the SLCO1B1 gene encoding OATP1B1 reduced the K(m) value for mesalazine uptake from 55.1 to 16.3, 24.3, and 32.4 μM, respectively, and the respective V(max) values. Finally, budesonide, cyclosporine, and rifampin were identified as inhibitors of OATP1B1-, OATP1B3-, and OATP2B1-meditated mesalazine uptake. These in vitro data indicate that OATP-mediated uptake and its modification by genetic factors and comedications may play a role for mesalazine effects.

The prevention of colitis-related cancer by 5-aminosalicylates: an appealing hypothesis that remains unproven

Whether or not 5-aminosalicylates can prevent colorectal cancer among patients with colitis remains an open question. The observational studies examining this question have provided conflicting results, but none of these studies have been of sufficient quality to provide a definitive answer one way or another.

The position of the amino group on the benzene ring is critical for mesalamine's improvement of replication fidelity

BACKGROUND

Individuals with ulcerative colitis are at high risk of developing colitis-associated cancer. 5-Aminosalicylate (5-ASA) protects from cancer by its antiinflammatory activity as well as by altering cell growth, inducing apoptosis, and reducing replication errors. So far neither 5-ASA's structural specificity nor its pharmacophore group have been identified. Here we compared 5-ASA with its analogs (4-ASA and 3-ASA) and its metabolite N-acetyl-5-ASA (NAc-5-ASA).

METHODS

Superoxide scavenging was analyzed by lucigenin-amplified chemiluminescence. Cell growth, cell cycle distribution, and replication fidelity at a (CA)13 microsatellite were measured in HCT116 and HT29 colon epithelial cells by MTT and flow cytometry. Nuclear protein extracts were blotted for replication protein A (RPA), claspin, p53, and p53(Ser15).

RESULTS

All compounds inhibited the growth of colon epithelial cells at a similar level and displayed potent scavenging properties, with 3-ASA being the most active, followed by 5-ASA, 4-ASA, and NAc-5-ASA. Besides 5-ASA, only 4-ASA caused an increase in the S-phase population (56%-69% and 49%-62% in HCT116 and HT29 cells, respectively). This was accompanied by nuclear recruitment of replication proteins RPA and claspin as well as phosphorylation of p53(Ser15), both of which were weaker or absent with 3-ASA or NAc-5-ASA. 5-ASA was the only compound that lowered mutations at a (CA)13 microsatellite.

CONCLUSIONS

5-ASA shares its growth inhibitory and superoxide scavenging properties with its structural analogs and metabolite, but the position of the amino group is critical for reducing replication errors.

Mesalazine reduces mutations in transforming growth factor beta receptor II and activin type II receptor by improvement of replication fidelity in mononucleotide repeats

PURPOSE

Mesalazine (5-aminosalicylic acid, 5-ASA) has chemopreventive properties in colitis-associated cancer. In vitro, it improves replication fidelity at (CA)13 microsatellites independent of mismatch repair proficiency. Therefore, 5-ASA might be advantageous in patients with hereditary nonpolyposis colorectal cancer. At this point, however, it is uncertain whether this improvement of replication fidelity is specific for (CA)13 repetitive sequences. Here, we tested the effect of 5-ASA on replication fidelity in mononucleotide, dinucleotide, and tetranucleotide repeats.

EXPERIMENTAL DESIGN

HCT116 and HCT116+chr3 cells were transfected with pIREShyg2-EGFP reporter plasmids harboring the following microsatellites: A10, G10, (CA)13, (CA)26, (AAAG)17, poly-A tracts, and their flanking sequences of transforming growth factor beta receptor II (TGFBR2; A10) and activin type II receptor (ACVR2; A8). Stably transfected single-cell clones were selected, characterized by Southern blotting, sorted into six-well plates, and cultured with or without 5-ASA. Frameshift mutations that shift the enhanced green fluorescence protein into its proper reading frame were quantified by flow cytometry.

RESULTS

In HCT116, 5-ASA reduced the mutant fraction at (CA)13 by 48.3%, at A10 by 35.6-43.6%, at G10 by 74.9-83.6%, and at (AAAG)17 by 37.6-44.4%. Similar results were observed in hMLH1-proficient HCT116+chr3 cells. Moreover, the presence of 5-ASA significantly reduced mutations in TGFBR2 (A10) and ACVR2 (A8) by 39.9% and 46.2%, respectively.

CONCLUSIONS

5-ASA increases replication fidelity in mononucleotide, dinucleotide, and tetranucleotide repeats and reduces mutations in tumor suppressor genes TGFBR2 and ACVR2, a finding that may provoke in vivo studies for the prevention of colorectal cancer in hereditary nonpolyposis colorectal cancer.

5-aminosalicylic acid interferes in the cell cycle of colorectal cancer cells and induces cell death modes

INTRODUCTION

Epidemiological data suggests that 5-aminosalicylic acid (5-ASA), a nonsteroidal antiinflammatory drug used in the treatment of inflammatory bowel diseases, prevents colorectal cancer development in these patients, although the mechanisms remain incompletely understood.

METHODS AND RESULTS

Here we report that 5-ASA prevents growth of several colorectal cancer cell lines by interfering in the cell cycle, i.e., an S-phase and G2/M phase arrest, dependent on 5-ASA dosage and concentration, together with an increased mitotic index. In addition, prolonged cell cycle arrest by repeated 5-ASA treatment induced apoptosis and caused abnormal spindle organization leading to mitotic catastrophe, another form of cell death.

CONCLUSION

These observations illustrate that 5-ASA has chemopreventive and chemotherapeutic properties.

Asian perspectives in the management of inflammatory bowel disease: findings from a recent survey

BACKGROUND AND AIM

The prevalence and incidence of inflammatory bowel disease (IBD) differs worldwide. While the prevalence of IBD has stabilized in Europe, the USA and Japan, an increasing trend has been observed in Asia. However, there are no data on the current clinical practice for the management of IBD in the region. The present study aims to investigate the number of existing and new cases of IBD and to understand the current practice of diagnosis and treatment of IBD in different Asian countries.

METHODS

A self-administered questionnaire, designed according to European and US guidelines, was distributed to IBD specialists throughout Asia. The questionnaire estimated the annual incidence of existing and new IBD cases in physicians' clinical practices and evaluated their procedures of diagnosis and preference for therapeutic treatment and maintenance treatment.

RESULTS

Eighty-seven questionnaires were received out of the 107 distributed. In the clinical practices of these 87 respondents, there were 502 existing and 73 new cases per year for ulcerative colitis (UC) and 202 existing and 32 new cases per year for Crohn's disease (CD). Colonoscopy and histology were the most commonly used methods for the diagnosis of UC and CD, but clinical practice regarding the diagnosis of IBD varied. The treatment of choice for mild-to-moderate UC and CD was 5-aminosalicylic acid (5-ASA), which is also the preferred choice for the maintenance treatment of UC and CD.

CONCLUSION

Clinical practice with regards to IBD diagnosis and management varies within Asia.5-ASA is the preferred treatment and maintenance therapy for mild-to-moderate IBD.

Mesalazine inhibits the beta-catenin signalling pathway acting through the upregulation of mu-protocadherin gene in colo-rectal cancer cells

BACKGROUND

Several reports indicate that mesalazine (5-aminosalicylic acid, 5-ASA) is a promising candidate for the chemoprevention of colo-rectal cancer because of its ability to reach the purpose avoiding the unwanted side effects usually associated with prolonged administration of nonsteroidal anti-inflammatory drugs. This activity of 5-ASA is probably the consequence of a number of effects determined on colo-rectal cancer cells, consisting of reduced proliferation, increased apoptosis and activation of cell cycle checkpoints and DNA repair processes. A recent observation has suggested that inhibition of beta-catenin signalling could induce these cellular effects.

AIM

To characterize better the capacity of 5-ASA to inhibit the beta-catenin signalling pathway.

METHODS

Genes belonging to the beta-catenin signalling pathway were analysed in colo-rectal cancer cell lines treated with 5-ASA using a combination of laboratory assays that are able to detect their phenotypic expression and functional activity.

RESULTS

The results obtained indicated that 5-ASA induces the expression of a protein called mu-protocadherin that belongs to the cadherin superfamily and is able to sequester beta-catenin on the plasmatic membrane of treated cells hampering its function.

CONCLUSION

These findings suggest that mu-protocadherin might be employed as a biological marker to monitor the chemopreventive efficacy of 5-ASA.

Chemoprevention of colonic polyps with balsalazide: an exploratory, double-blind, placebo-controlled study

BACKGROUND

A number of agents, including aspirin, nonsteroidal antiinflammatory drugs, cyclooxygenase-2 inhibitors, folic acid, calcium, and vitamins, have been evaluated for their potential in chemoprevention of sporadic colorectal adenomas or cancer. Preclinical data suggest that 5-aminosalicylates also may have a chemopreventive effect.

AIM

To investigate chemoprevention of colonic polyps with balsalazide, a 5-aminosalicylate prodrug.

METHODS

In this randomized, double-blind, placebo-controlled study, adults diagnosed with small polyps in the rectosigmoid colon were treated with either balsalazide 3 g/d or placebo for 6 months. Follow-up lower endoscopy was performed, and all polyps were measured and analyzed histologically. The primary endpoint was reduction in mean size of the largest polyp per subject.

RESULTS

Among 241 participants screened, 86 were randomized to treatment, with 75 subjects evaluable. Balsalazide 3 g/d (n = 38) did not significantly reduce the mean size of the largest colonic polyp or the number of polyps compared with placebo (n = 37). Although not significant, post-hoc analysis revealed that total adenoma burden per subject, calculated as the sum of the volumes of all adenomas in mm3, increased by 55% in the balsalazide group compared with 95% in the placebo group.

CONCLUSIONS

Although balsalazide did not have significant chemopreventive effects on established colonic polyps, these results can aid in designing future prospective studies.

In vivo effects of mesalazine or E. coli Nissle 1917 on microsatellite instability in ulcerative colitis

BACKGROUND

Microsatellite instability (MSI) occurs in chronically inflamed colorectal tissue and may evolve to colitis-associated cancer. In vitro data suggest that mesalazine (5-ASA) improves MSI.

AIM

To analyse the changes in MSI in 156 distal colonic biopsies of 39 patients with ulcerative colitis that had been treated within a randomized, double-blind trial comparing 5-ASA with E. coli Nissle (EcN).

METHODS

Two biopsies had been collected before and after 1 year of treatment. MSI testing was performed using a panel of eight markers, including 3 dinucleotide and 5 mononucleotide repeats.

RESULTS

No MSI was observed with any of the mono-repeats, and among dinucleotide repeats, only D5S346 (maps to APC) and D17S250 (p53) were consistently informative. Overall, 31/156 (20%) biopsies displayed MSI. After 1 year, 3/11 patients displayed MSI improvement [change to microsatellite stability (MSS); 1 on 5-ASA, 2 on EcN] at D5S346 and 4/11 showed MSI worsening (change from MSS to MSI; all 5-ASA). For D17S250, the corresponding data were for 3/9 patients (2 on 5-ASA, 1 on EcN) and 2/9 (both on 5-ASA), respectively.

CONCLUSIONS

In the set of biopsies taken from patients treated with 1.5 g 5-ASA for 1 year, there was no improvement in the prevalence of MSI in the distal colon.

Cost effectiveness of ulcerative colitis surveillance in the setting of 5-aminosalicylates

OBJECTIVES

Colorectal cancer (CRC) is a feared complication of chronic ulcerative colitis (UC). Annual endoscopic surveillance is recommended for the detection of early neoplasia. 5-Aminosalicylates (5-ASAs) may prevent some UC-associated CRC. Therefore, in patients prescribed 5-ASAs for maintenance of remission, annual surveillance might be overly burdensome and inefficient. We aimed to determine the ideal frequency of surveillance in patients with UC maintained on 5-ASAs.

METHODS

We performed systematic reviews of the literature, and created a Markov computer model simulating a cohort of 35-year-old men with chronic UC, followed until the age of 90 years. Twenty-two strategies were modeled: natural history (no 5-ASA or surveillance), surveillance without 5-ASA at intervals of 1-10 years, 5-ASA plus surveillance every 1-10 years, and 5-ASA alone. The primary outcome was the ideal interval of surveillance in the setting of 5-ASA maintenance, assuming a third-party payer was willing to pay $100,000 for each quality-adjusted life-year (QALY) gained.

RESULTS

In the natural history strategy, the CRC incidence was 30%. Without 5-ASA, annual surveillance was the ideal strategy, preventing 89% of CRC and costing $69,100 per QALY gained compared with surveillance every 2 years. 5-ASA alone prevented 49% of CRC. In the setting of 5-ASA, surveillance every 3 years was ideal, preventing 87% of CRC. 5-ASA with surveillance every 2 years cost an additional $147,500 per QALY gained, and 5-ASA with annual surveillance cost nearly $1 million additional per QALY gained compared with every 2 years. In Monte Carlo simulations, surveillance every 2 years or less often was ideal in 95% of simulations.

CONCLUSIONS

If 5-ASA is efficacious chemoprevention for UC-associated CRC, endoscopic surveillance might be safely performed every 2 years or less often. Such practice could decrease burdens to patients and on endoscopic resources with a minimal decrease in quality-adjusted length of life, because 5-ASA with annual surveillance may cost nearly $1 million per additional QALY gained.

Incidence and prognosis of cholangiocarcinoma in Danish patients with and without inflammatory bowel disease: a national cohort study, 1978-2003

Patients with inflammatory bowel disease (IBD) are at increased risk of cholangiocarcinoma (CC), but quantitative data are scant. Furthermore, little is known about the impact of IBD on CC occurrence and prognosis. Based on nationwide population-based registries we compared the incidence and survival of CC patients with and without IBD from 1978 to 2003. We used the National Registry of Patients and the Danish Cancer Registry to identify patients with IBD and CC. From the Civil Registration System we identified population controls. We calculated incidence rates, incidence rate ratios (compared with population controls), and absolute cumulative risks. We also computed median survival in CC patients with and without IBD. 2,725 CC patients were identified. The incidence of CC among the 41,280 IBD patients was 7.6 per 100,000 person years compared with 1.9 per 100,000 among the 412,796 population controls (four-fold increased risk). The 10 year cumulative risk of CC in IBD patients was 0.07%. Sub analyses showed that the increased risk of CC was more pronounced in male IBD patients and in patients with ulcerative colitis. We found a decreasing CC incidence in IBD patients over calendar time. CC patients with IBD were, on average, 15 years younger at cancer diagnosis than IBD-free CC patients, and median survival was 1 month in both groups. In conclusion, the absolute risk of CC in IBD patients was low and the CC incidence decreased over calendar time. The prognosis was equally grave, regardless of the presence of IBD.