Colorectal cancer in inflammatory bowel disease

SMAD2 and the Relationship of Colorectal Cancer to Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) affecting the colon [Crohn's disease (CD) and ulcerative colitis (UC)] are associated with an increased risk of colorectal cancer (CRC). Our previous work using oligonucleotide array data indicated that SMAD2 was significantly underexpressed in UC dysplastic tissue compared to benign UC. The aim of this current study was to determine whether single nucleotide polymorphisms (SNPs) within the SMAD2 gene are associated with IBD dysplasia/cancer. We performed an SNP haplotype-based case-control association study. Leukocyte DNA was obtained from 489 unrelated Caucasians (158 UC, 175 CD, 71 CRC, 85 controls). Eleven SNPs were genotyped. All 11 SNPs were in Hardy-Weinberg equilibrium in the control population. Strong linkage disequilibrium was observed among nearly all SMAD2 SNPs. There were no significant associations between SMAD2 allele or haplotype frequencies. Power calculations indicated good power for single-marker analysis (>0.8) and reasonably good power against effects of 0.1–0.15 for haplotype analysis. SMAD2 SNPs were not associated with the development of IBD dysplasia/cancer. This incongruity between our previous microarray data and the findings from this genotype study may be attributed to mechanisms such as alternative splicing of pre-mRNA SMAD2 and/or cross talk with other cellular pathways.

Impact of mucosal inflammation on risk of colorectal neoplasia in patients with ulcerative colitis: a systematic review and meta-analysis

BACKGROUND AND AIMS

Long-standing ulcerative colitis is an established risk factor for colorectal neoplasia. A number of observational studies have suggested that evidence of mucosal inflammation (endoscopic or histologic) is associated with a greater risk for colorectal neoplasia than is mucosal healing. Our goal was to systematically analyze the risk of colorectal neoplasia in patients with ulcerative colitis who have ongoing mucosal inflammation to better inform surveillance strategies.

METHODS

We performed a systematic review and meta-analysis of the effect of endoscopic and/or histologic inflammation on the risk of colorectal neoplasia in cohort and case-control studies. Sensitivity analyses for study setting and case definition were performed.

RESULTS

Six studies met the inclusion criteria, incorporating outcomes in 1443 patients. No study used a single validated measure for mucosal inflammation. The pooled odds ratio for colorectal neoplasia was 3.5 (95% confidence interval [CI], 2.6-4.8; P < .001) in those with any mucosal inflammation and 2.6 (95% CI, 1.5-4.5; P = .01) in those with histologic inflammation, when compared with those with mucosal healing. The overall quality of the studies was good.

CONCLUSION

The presence of objective evidence of mucosal inflammation during follow-up in patients with ulcerative colitis is associated with a greater risk of subsequent colorectal neoplasia than in those with mucosal healing. This risk factor should be considered in guidelines on surveillance intervals for these patients.

Chemoprevention of colorectal cancer in ulcerative colitis: digging deep in current evidence

Patients with ulcerative colitis (UC) have an increased risk of developing colorectal cancer (CRC). Surveillance colonoscopy is currently recommended for patients with long-standing extensive colitis for reducing CRC risk. Chemoprevention is an attractive complementary strategy. Areas covered: Inflammation is a major determinant of CRC risk and is potentially modifiable. Reducing inflammation is supposed to reduce CRC risk. Several medications have been evaluated in this setting: 5-ASA, thiopurines, anti-TNFα agents and ursodeoxycholic acid (UCDA) in patients with associated primary sclerosing cholangitis (PSC). This review offers a critical evaluation of current evidence of the potential chemopreventive effect of such medications. Expert commentary: No randomized controlled trials have been performed and the available evidence come from observational studies. Although biological plausibility supports a chemopreventive role of the aforementioned agents, the overall evidence of efficacy is weak because of several methodological limitations of the studies. Indirect epidemiological evidence, biologic plausibility and results of meta-analyses reasonably support a potential chemopreventive effect of 5-ASA. Available evidence does not support a specific chemopreventive effect of purine analogues and anti-TNFα medications, despite their efficacy in the management of inflammatory bowel disease. Data addressing UDCA and folate supplementation are inconclusive. Limited data are available for statins.

IFN-γ-mediated IRF1/miR-29b feedback loop suppresses colorectal cancer cell growth and metastasis by repressing IGF1

To investigate the clinicopathological significance and underlying mechanism of microRNA-29b (miR-29b) in colorectal cancer (CRC), the role of miR-29b was investigated using in vivo and in vitro assays. Luciferase reporter assays were conducted to determine the association between miR-29b and the insulin-like growth factor 1 (IGF1) 3' untranslated region (3'UTR). Chromatin immunoprecipitation (ChIP) assays were employed to assess the direct binding of interferon regulatory factor 1 (IRF1) to miR-29b. We found that interferon (IFN)-γ could induce miR-29b by recruiting IRF1 to binding sites in the miR-29b promoter. A low level of miR-29b was significantly associated with an aggressive phenotype. MiR-29b inhibited CRC cell growth and invasion. IGF1, an activator of PI3K/Akt signaling, was confirmed as a novel target of miR-29b. Moreover, miR-29b increased IRF1 expression, and the inhibition of miR-29b suppressed IFN-γ-induced apoptosis. We elucidated the potential signaling pathway, IFN-γ/IRF1/miR-29b/IGF1, and its implication for CRC tumorigenesis. A positive feedback loop between IRF1 and miR-29b may contribute to the sensitivity of CRC cells to IFN-γ. Targeting miR-29b may provide a strategy for blocking CRC growth and metastasis.

IFN-γ-driven intratumoral microenvironment exhibits superior prognostic effect compared with an IFN-α-driven microenvironment in patients with colon carcinoma

Interferon (IFN)-α and IFN-γ are cytokines with potent immunomodulating and anti-tumor activities. It is unknown which of the two IFNs may be more potent in the regulation of an anti-tumorigenic response in colorectal carcinoma or whether both cytokines cooperate. We, therefore, established human myxovirus resistance protein A and human guanylate-binding protein-1 as markers for the differential detection of IFN-α- and IFN-γ-driven tumor micromilieus, respectively. In vitro studies with different cultures of tumor cells from colorectal carcinoma and stroma cells showed that the expression of myxovirus resistance protein A was exclusively induced by IFN-α, whereas guanylate-binding protein-1 was strongly induced by IFN-γ and only weakly by IFN-α. This expression pattern was used to distinguish cell activation caused by the two cytokines in a clinical cohort of patients with colon carcinoma (n = 378). Patients with primary tumors expressing only guanylate-binding protein-1 exhibited the highest cancer-specific 5-year survival (94.0%, P = 0.006) compared with those expressing both factors (90.3%, P = 0.006), myxovirus resistance protein A alone (83.5%, P = 0.096), or none (72.8%). Our study describes a successful proof-of-principle approach that complex cytokine interaction networks can be dissected in human tissues and demonstrates that an IFN-γ-driven tumor microenvironment exhibits a superior prognostic effect compared with an IFN-α-driven tumor microenvironment in colon carcinoma.

Aneuploidy-associated gene expression signatures characterize malignant transformation in ulcerative colitis

BACKGROUND

Malignant transformation in ulcerative colitis (UC) is associated with pronounced chromosomal instability, reflected by aneuploidy. Although aneuploidy can precede primary cancer diagnosis in UC for more than a decade, little is known of its cellular consequences.

METHODS

Whole-genome gene expression analysis was applied to noninflamed colon mucosa, mucosal biopsies of patients with UC, and UC-associated carcinomas (UCCs). DNA image cytometry was used to stratify samples into ploidy types. Differentially expressed genes (DEGs) were analyzed by Ingenuity Pathway Analysis and validated by real-time quantitative PCR.

RESULTS

Gene expression changes were more pronounced between normal mucosa and UC (2587 DEGs) than between UC and UCC (827 DEGs). Cytometry identified colitis patients with euploid or aneuploid mucosa biopsies, whereas all UCCs were aneuploid. However, 1749 DEGs distinguished euploid UC and UCCs, whereas only 15 DEGs differentiated aneuploid UC and UCCs. A total of 16 genes were differentially expressed throughout the whole sequence from normal controls to UCCs. Particularly, genes pivotal for chromosome segregation (e.g., SMC3 and NUF2) were differentially regulated along aneuploidy development.

CONCLUSIONS

The high number of DEGs between normal mucosa and colitis is dominated by inflammatory-associated genes. Subsequent acquisition of aneuploidy leads to subtle but distinct transcriptional alterations, revealing novel target genes that drive genomic instability and thus carcinogenesis. The gene expression signature of malignant phenotypes in aneuploid UC suggests that these lesions might need to be considered as severe as high-grade dysplasia.

Transcription factor NFATc2 controls the emergence of colon cancer associated with IL-6-dependent colitis

NFAT transcription factors control T-cell activation and function. Specifically, the transcription factor NFATc2 affects the regulation of cell differentiation and growth and plays a critical role in the development of colonic inflammation. Here, we used an experimental model of colitis-associated colorectal carcinoma to investigate the contribution of NFATc2 to the promotion of colonic tumors. Compared with wild-type animals that readily presented with multiple colon tumors, NFATc2-deficient mice were protected from tumor development. This observed decrease in colonic tumor progression was associated with reduced endoscopic inflammation, increased apoptosis of lamina propria T lymphocytes, and significantly reduced levels of the critical proinflammatory cytokines interleukin (IL)-21 and IL-6. Administration of hyper IL-6 abrogated protection from tumor progression in NFATc2-knockout mice and restored tumor incidence to control levels. Taken together, our findings highlight a pivotal role for NFATc2 in the establishment of inflammation-associated colorectal tumors mediated by control of IL-6 expression.

Molecular imaging agents: impact on diagnosis and therapeutics in oncology

Imaging has become a crucial tool in oncology throughout the course of disease detection and management, and is an integral part of clinical trials. Anatomical and functional imaging led the way, providing valuable information used in the diagnosis of disease, including data regarding the size and location of the tumour and on physiological processes such as blood flow and perfusion. As understanding of cancer pathogenesis has advanced through the identification of genetic, biochemical and cellular alterations in evolving tumours, emphasis has been put on developing methods to detect and serially monitor such alterations. This class of approaches is referred to as molecular imaging. Molecular imaging offers the potential for increasingly sensitive and specific visualisation and quantification of biological processes at the cellular and molecular level. These approaches have become established as essential tools for cancer research, early cancer detection and staging, and monitoring and predicting response to targeted therapies. Here, we discuss recent advances in the development of molecular imaging agents and their implementation in basic cancer research as well as in more rationalised approaches to cancer care.

Triptolide downregulates Rac1 and the JAK/STAT3 pathway and inhibits colitis-related colon cancer progression

Triptolide, a diterpenoid triepoxide from the traditional Chinese medicinal herb Tripterygium wilfordii Hook. f., is a potential treatment for autoimmune diseases as well a possible anti-tumor agent. It inhibits proliferation of colorectal cancer cells in vitro and in vivo. In this study, its ability to block progress of colitis to colon cancer, and its molecular mechanism of action are investigated. A mouse model for colitis-induced colorectal cancer was used to test the effect of triptolide on cancer progression. Treatment of mice with triptolide decreased the incidence of colon cancer formation, and increased survival rate. Moreover, triptolide decreased the incidence of tumors in nude mice inoculated with cultured colon cancer cells dose-dependently. In vitro, triptolide inhibited the proliferation, migration and colony formation of colon cancer cells. Secretion of IL6 and levels of JAK1, IL6R and phosphorylated STAT3 were all reduced by triptolide treatment. Triptolide prohibited Rac1 activity and blocked cyclin D1 and CDK4 expression, leading to G1 arrest. Triptolide interrupted the IL6R-JAK/STAT pathway that is crucial for cell proliferation, survival, and inflammation. This suggests that triptolide might be a candidate for prevention of colitis induced colon cancer because it reduces inflammation and prevents tumor formation and development.

Clinical study of the relationship between inflammatory bowel diseases and colorectal neoplasms

OBJECTIVE

To investigate the incidence of colorectal cancer in inflammatory bowel disease (IBD) patients and its risk factors.

METHODS

Data on 513 patients in the last 10 years from Ruijin Hospital were collected. Their medical histories were put in database and analyzed including their socio-demographic features, pathogenetic conditions, diagnostic methods, possible related risk factors, treatment and outcome.

RESULTS

Among the 513 were 242 with ulcerative colitis (UC), among whom four patients developed cancers and four had precancerous lesions. None of the 271 CD patients developed cancer. The incidence of both cancer and precancerosis in the UC patients was 1.65%. Through multifactorial logistic regression analysis, loss of weight, other disease complications and frequent relapses were proved to be the most probable risk factors.

CONCLUSION

The incidence of IBD has kept on rising in recent years. Clinically, UC patients have more probability of developing colorectal cancer than CD patients. The main risk factors of developing colorectal cancer in UC patients are frequent relapses, weight loss and other complications.

Colon cancer stem cells: implications for prevention and therapy

The recent identification of colon cancer tumor-initiating cells adds further support to the cancer stem cell hypothesis. Ongoing basic and translational research efforts are aimed at gaining an increased understanding of the biology of these cells, as well as methods of targeting them. In addition, the relationship between colon carcinogenesis and inflammatory conditions, such as longstanding colitis and inherited syndromes, might be linked to the effect of the processes on stem cells in the colon. This review summarizes current literature on colon cancer stem cells and proposes strategies aimed at targeting these cells for colon cancer prevention and therapy.

Angiostatic immune reaction in colorectal carcinoma: Impact on survival and perspectives for antiangiogenic therapy

Angiogenesis and inflammation are the 2 major stroma reactions in colorectal carcinoma (CRC). Guanylate binding protein-1 (GBP-1) is a key mediator of angiostatic effects of inflammation. Therefore, we hypothesized that GBP-1 may be a biomarker of intrinsic angiostasis associated with an improved outcome in CRC patients. GBP-1 was strongly expressed in endothelial cells and immune cells in the desmoplastic stroma of 32% of CRC as determined by immunohistochemical investigation of 388 sporadic CRC. Cancer-related 5-year survival was highly significant (p < 0.001) increased (16.2%) in patients with GBP-1-positive CRC. Multivariate analysis showed that GBP-1 is an independent prognostic factor indicating a reduction of the relative risk of cancer-related death by the half (p = 0.032). A comparative transcriptome analysis (22,215 probe sets) of GBP-1-positive (n = 12) and -negative (n = 12) tumors showed that particularly IFN-gamma-induced genes including the major antiangiogenic chemokines CXCL9, CXCL10 and CXCL11 were coexpressed with GBP-1. Altogether our findings indicated that GBP-1 may be a novel biomarker and an active component of a Th-1-like angiostatic immune reaction in CRC. This reaction may affect patient's response to antiangiogenic therapy and the identification of such tumors may provide a novel criterion for patient selection. Moreover, the induction of a Th-1-like angiostatic immune reaction may be a promising approach for the clinical treatment of CRC.

Diagnostics of inflammatory bowel disease

The diagnosis of inflammatory bowel disease (IBD) with its 2 main subforms, Crohn's disease and ulcerative colitis, is based on clinical, endoscopic, radiologic, and histologic criteria. This paradigm remains unchanged despite the advent of new molecular technologies for the examination of serum proteins and genetic sequences, respectively. The main innovations in diagnostic technologies include the development of more sophisticated endoscopic and noninvasive imaging techniques with the aim of improving the identification of complications, in particular malignant diseases associated with IBD. The future will see further progress in the identification of genetic susceptibility factors and of protein biomarkers and their use to describe the molecular epidemiology of IBD. It can be expected that future diagnostic algorithms will include molecular parameters to detect early disease or guide therapies by predicting the individual course of disease.

The risk of cancer in patients with Crohn's disease

PURPOSE

The risk of cancer in patients with Crohn's disease is not well defined. Using meta-analytical techniques, the present study was designed to quantify the risk of intestinal, extraintestinal, and hemopoietic malignancies in such patients.

METHODS

A literature search identified 34 studies of 60,122 patients with Crohn's disease. The incidence and relative risk of cancer were calculated for patients with Crohn's disease and compared with the baseline population of patients without Crohn's disease. Overall pooled estimates, with 95 percent confidence intervals, were obtained, using a random-effects model.

RESULTS

The relative risk of small bowel, colorectal, extraintestinal cancer, and lymphoma compared with the baseline population was 28.4 (95 percent confidence interval, 14.46-55.66), 2.4 (95 percent confidence interval, 1.56-4.36), 1.27 (95 percent confidence interval, 1.1-1.47), and 1.42 (95 percent confidence interval, 1.16-1.73), respectively. On subgroup analysis, patients with Crohn's disease had an increased risk of colon cancer (relative risk, 2.59; 95 percent confidence interval, 1.54-4.36) but not of rectal cancer (relative risk, 1.46; 95 percent confidence interval, 0.8-2.55). There was significant association between the anatomic location of the diseased bowel and the risk of cancer in that segment. The risk of small bowel cancer and colorectal cancer was found to be higher in North America and the United Kingdom than in Scandinavian countries with no evidence of temporal changes in the cancer incidence.

CONCLUSIONS

The present meta-analysis demonstrated an increased risk of small bowel, colon, extraintestinal cancers, and lymphoma in patients with Crohn's disease. Patients with extensive colonic disease that has been present from a young age should be candidates for endoscopic surveillance; however, further data are required to evaluate the risk of neoplasia over time.

Colonic adenocarcinomas: near-infrared microcatheter imaging of smart probes for early detection--study in mice

PURPOSE

To prospectively evaluate the ability of micro-fiberoptic catheters, which simultaneously record white light and near-infrared (NIR) images, to reveal colonic neoplasms after the intravenous administration of activatable "smart" probes that increase in NIR fluorescence subsequent to protease activation.

MATERIALS AND METHODS

The institutional animal care committee approved all animal experiments. CT26 tumor cells were orthotopically implanted into the descending colon of C57BL6/J mice (n=10). Thirteen days later, mice intravenously received either 2 nmol of a protease-sensing probe that had cathepsin B as a major activator (n=5) or saline (control animals [n=5]). One day later, animals were noninvasively examined to the point of the splenic flexure by using microcatheter imaging. Excised colons were subsequently evaluated with epifluorescence imaging, histologic examination, and cathepsin B immunohistochemistry. Student t test was used for statistical analysis, with P<.05 considered to indicate a significant difference.

RESULTS

Results with fiberoptic imaging demonstrated that all tumors were visible with the protease-activatable probe, even when they were not readily apparent at white light imaging. A target-to-background ratio (TBR) of 8.86 for tumor to adjacent normal mucosa was achieved in the NIR channel after probe administration (P=.001), whereas white light images resulted in a TBR of 1.14 (P>.5) based on luminosity. The tumoral NIR fluorescence intensity was more than 30-fold greater in probe-injected animals than in control animals, indicating that essentially all of the signal recorded in lesions was from activatable probe administration. Results of immunohistochemistry confirmed cathepsin B overexpression in the tumor compared with adjacent mucosa.

CONCLUSION

The use of NIR imaging microcatheters combined with protease-activatable smart probes results in a beacon effect that highlights tumors with high TBRs; this technique thus may be a potentially useful adjunct to white light colonoscopy in the future.

Optical adjuncts for enhanced colonoscopic diagnosis

Background

Optical techniques using previously unexploited properties of light interaction with tissue may be valuable in the detection, diagnosis and staging of colorectal neoplasia.

Methods

A Medline search (1990 to present) was conducted on optical diagnostics in the detection of colorectal neoplasia. The reference list of each identified article was reviewed for further relevant papers.

Results and conclusion

Chromoendoscopy is the only optical adjunct to colonoscopy that has been tested in large randomized clinical trials. It improves the detection of small and flat colorectal adenomas, and of neoplasia in chronic ulcerative colitis and hereditary non-polyposis colorectal cancer. All other techniques are the subject of ongoing research and the practicality of population screening with any of the methods has yet to be established. Optical techniques may, however, permit immediate clinical diagnosis, removing the need for histological analysis. They may also improve the diagnosis of early colonic neoplasia.

Carcinogenesis in inflammatory bowel disease

Patients with longstanding ulcerative colitis (UC) and Crohn's disease (CD) have an increased risk of colorectal cancer (CRC). CRC accounts for approximately 15% of all deaths in patients with inflammatory bowel disease (IBD). The molecular pathway leading to CRC in IBD appears to differ from the well-known adenoma-to-CRC sequence, given the fact that these cancers appear to arise from either flat dysplastic tissue or dysplasia-associated lesions or masses. The risk of CRC for patients with IBD increases by 0.5-1% yearly, 8-10 years after diagnosis. Patients with a young age at disease onset, more extensive colitis, greater inflammatory burden, concomitant primary sclerosing cholangitis, and a family history of CRC are at greatest risk. Most cancers arise in pancolitis and there is little or no increased risk associated with proctitis while left-sided colitis carries an intermediate cancer risk. The CRC risk in patients with colonic CD is similar to that of UC. Colonic dysplasia is a precursor to CRC in IBD. There is no clear evidence that surveillance colonoscopy prolongs survival in patients with extensive colitis. Newer endoscopic and molecular techniques are being assessed for their effectiveness in augmenting conventional surveillance.

The histological diagnosis of dysplastic and neoplastic lesions in inflammatory bowel disease: a pathological perspective

Patients with inflammatory bowel disease (IBD), both ulcerative colitis (UC) and Crohn's disease (CD), are at an increased risk for developing colorectal carcinoma (CRC). The accurate diagnosis of dysplasia in biopsies taken during periodic surveillance of long-standing IBD patients is most important in prevention of UC and CD related cancer. Distinction of low from high grade IBD-related dysplasia and differential diagnosis between IBD-related dysplasia and dysplasia in sporadic adenoma as well as distinction from pseudodysplastic lesions in inflammatory pseudopolyps or reparative lesions is often very subtle and difficult and demands expertise of second experienced gastrointestinal pathologist. Although surveillance colonoscopy with multiple biopsies does not reduce the cancer mortality, it offers a reasonable chance of detecting precancer and performed prophylactic colectomy. Novel methods of detecting dysplasia are continuously being evaluated, including chromoscopy and molecular biology markers. In the future, one may expect, from these new markers to detect the dysplasia in IBD patients before development of histological evidence of neoplastic changes.

Colorectal cancer

Every year, more than 945000 people develop colorectal cancer worldwide, and around 492000 patients die. This form of cancer develops sporadically, in the setting of hereditary cancer syndromes, or on the basis of inflammatory bowel diseases. Screening and prevention programmes are available for all these causes and should be more widely publicised. The adenoma-carcinoma sequence is the basis for development of colorectal cancer, and the underlying molecular changes have largely been identified. Prognosis depends on factors related to the patient, treatment, and tumour, and the expertise of the treatment team is one of the major determinants of outcome. New information on the molecular basis of this cancer have led to the development of targeted therapeutic options, which are being tested in clinical trials. Further clinical progress will largely depend on the broader implementation of multidisciplinary treatment strategies following the principles of evidence-based medicine.

Detection of invasive colon cancer using a novel, targeted, library-derived fluorescent peptide

Sensitive methods to detect the earliest forms of colorectal cancers remain a challenge despite the development of serum and stool biomarkers. We reasoned that fluorescent affinity ligands derived from library screens can be developed to improve the detection and localization of early malignant lesions by endoscopy. We have developed an imaging agent for real-time endoscopic tumor detection in a murine model using a previously identified phage library-derived colon cancer-specific cyclic peptide and fluorescent moieties. The modified peptide had a 24 minute blood half life and tumoral accumulation was 6.9% of injected dose/g, approximately 7-fold higher than a scrambled control peptide. Orthotopic colonic tumors (HT29) were readily detectable by fluorescence endoscopy even when tumors were submucosal. These results show proof-of-principle that disease-specific library-derived fluorescent probes can be rapidly developed for use in the early detection of cancers by optical means.