M. Robert Eichenberger

Differential microRNA expression tracks neoplastic progression in inflammatory bowel disease-associated colorectal cancer.

One of the most serious complications faced by patients with inflammatory bowel disease (IBD) is the potential development of colorectal cancer (CRC). There is a compelling need to enhance the accuracy of cancer screening of IBD patients. MicroRNAs (miRNAs) are small nonprotein‐coding RNAs that play important roles in CRC oncogenesis. In this study, we report differential miRNA expression in IBD patients with associated CRC from non‐neoplastic tissue to dysplasia and eventually cancer. In addition, we identify and examine the role of dysregulated miRNAs in the TP53 pathway. In our CD patients, six miRNAs were upregulated from non‐neoplastic tissue to dysplasia, but downregulated from dysplasia to cancer (miR‐122, miR‐181a, miR‐146b‐5p, let‐7e, miR‐17, miR‐143) (P < 0.001). Six differentially expressed miRNAs affected the TP53 pathway (miR‐122, miR‐214, miR‐372, miR‐15b, let‐7e, miR‐17) (P < 0.001). Using two human colon cancer cell lines (HT‐29 and HCT‐116), E2F1, an upstream regulator of TP53, was downregulated in both cell lines transfected with let‐7e (P < 0.05) as well as in HCT‐116 cells transfected with miR‐17 (P < 0.05). Additionally, cyclin G, a cell‐cycle regulator miR‐122 target was downregulated in both cell lines (P < 0.05). Unique differentially expressed miRNAs were observed in CD‐associated CRC progression. Six of these miRNAs had a tumorigenic effect on the TP53 pathway; the effect of three of which was studied using cell lines. Hum Mutat 33:551–560, 2012.

Inflammatory bowel disease and African Americans: A systematic review

Background: Inflammatory bowel disease (IBD) is comprised of Crohns disease (CD) and ulcerative colitis (UC). There are conflicting reports on whether African Americans have a more severe disease course, presentation, and more frequent extraintestinal manifestations (EIM). We examined the precise nature of this relationship by conducting a systematic review. Methods: Using predefined inclusion criteria we searched multiple healthcare databases and Grey literature. Eight reports met the inclusion criteria. Using the parameters as defined in the Montreal classification and the presence or absence of EIM, we compared IBD in African Americans and Caucasians. Results: Over 2000 IBD cases were pooled from 8 reports with African Americans comprising 17%. African Americans and Caucasians had similar distribution of types of IBD, with CD being more common than UC in both groups (CD 76% versus 68% and UC 24% versus 32%, respectively). With respect to CD, both groups presented with nonstricturing and nonpenetrating disease behavior (55% versus 41%) more frequently and had similar rates of ileocolonic disease location (42% versus 38%), and presence of perianal disease (26% versus 29%). In UC patients, proctitis was the most frequent initial presentation in both races. Joint complications were the most frequent EIM in both African Americans (52%) and Caucasians (60%). Conclusions: This study dispels the commonly held views that African Americans with IBD generally have more colonic disease, more severe disease behavior, and more perianal disease than Caucasians. African Americans also have similar variety and frequency of EIMs as compared to Caucasians.

Wingless-type frizzled protein receptor signaling and its putative role in human colon cancer

We wish to identify new candidate genes involved in the pathogenesis of human colon cancer to better understand the diversity of phenotype presentation that varies from individual to individual. Our working hypothesis is that genetic polymorphism of genes in the Wingless‐type (Wnt) frizzled protein receptor pathway is associated with the susceptibility to develop colon cancer. The putative role of the Wnt pathway in sporadic human malignancy of the colon suggests involvement in inherited cancer as well. β‐catenin is the crucial messenger in frizzled receptor signaling, transmitting Wnt‐ligand signals such as signals from secreted apoptosis‐related proteins to the nucleus. It functions as a genome denunciator by initiating amplification of oncogenes. The net effect of β‐catenin depends on the magnitude of its accumulation in the cytoplasm and, therefore, upon expression profiles of genes in the Wnt pathway. We propose that variations in allelic frequencies of genes involved in the β‐catenin cascade may either promote or impede malignant transformation of the colon. If certain polymorphisms in Wnt signaling through β‐catenin predispose to colon cancer, this might manifest as decreased binding affinity of proteins such as axin or the adenomatous polyposis coli protein to β‐catenin. Association studies are proposed to test the hypothesis, which could serve as an initial step toward understanding the complexity of tumor biology. The clinical rationale in unraveling the genetic susceptibility to cancer lies in identification of a subgroup of individuals who may benefit from β‐catenin targeting agents, which could potentially overcome this genetic instability.

CARD15 Genotype-Phenotype Relationships in a Small Inflammatory Bowel Disease Population with Severe Disease Affection Status

Inflammatory bowel disease (IBD; MIM# 266600) is subdivided on the basis of clinical findings as either Crohn’s disease (CD), ulcerative colitis (UC), or indeterminate colitis (IC). Three previously described mutations within the IBD susceptibility gene CARD15 (R702W, G908R, 1007fs) increase susceptibility to CD with a terminal ileal and/or ileocolonic location and fibrostenosing behavior. We undertook an association study using 477 unrelated IBD patients (248 CD, 172 UC, 57 IC) and 104 population controls to determine whether these previously described associations could be replicated in a small, accurately phenotyped cohort. Case-control and family-based approaches were employed to analyze CARD15 mutant allele and haplotype data. Analyses were initially performed in unstratified IBD cohorts. The R702W mutant allele was associated with CD on case-control analysis (q=0.036, P=.004), and 1007fs with CD on pedigree disequilibrium testing (P=.020). All 3 CARD15 mutations increased susceptibility to a variety of CD subphenotypic manifestations, including early-onset CD in individuals with a family history of IBD, and CD complicated by extraintestinal disease. We also present evidence to suggest that R702W may predispose to a more generalized form of CD. Additionally, we confirm that CARD15 mutations are associated with terminal ileal/ileocolonic, and to a lesser extent, fibrostenosing CD.

Association of Susceptibility Locus for Inflammatory Bowel Disease on Chromosome 16 with Both Ulcerative Colitis and Crohn's Disease

A susceptibility locus for inflammatory bowel disease (IBD) on chromosome 16 (IBD1) has been linked to Crohns disease in genome-wide linkage studies. We performed a case–control study with two markers for this locus using leukocyte DNA from 127 Crohns patients, 83 ulcerative colitis patients, and 74 control patients. Allele, genotype, and haplotype frequencies of the polymerase chain reaction products were determined using autoradiography. Haplotype frequencies differed for ulcerative colitis and Crohns disease, particularly for haplotype CC (22% ulcerative colitis vs 10% Crohns disease, P = 0.002 χ2 = 10.0) and haplotype CD (18% Crohns disease vs 9% ulcerative colitis, P = 0.025 χ2 = 5.02). These data demonstrate the association of the IBD1 locus with both ulcerative colitis and Crohns disease in a group of unrelated IBD patients. The use of such microsatellite markers when combined with others, might help distinguish ulcerative colitis from Crohns disease in patients with ambiguous clinical and histological features.

An alternative cyclin-D1 splice site is not linked to inflammatory bowel disease-associated neoplasia.

Background Inflammatory bowel diseases (IBD) encompass inflammatory disorders affecting the gastrointestinal tract, primarily ulcerative colitis (UC) and Crohns disease (CD). The risk of developing colorectal cancer (CRC) is increased in patients with IBD. The CCND1 protein is the regulatory subunit of an enzyme that inactivates the retinoblastoma protein, a tumor suppressor protein, and promotes progression through the G1-S phase of the cell cycle. The CCND1 870G-A gene polymorphism influences susceptibility to colorectal cancer. The mutant allele of CCND1 in IBD-associated neoplasia leads to a greater frequency of alternate splicing during transcription, resulting in a more stable CCND1 protein. This creates a higher concentration of CCND1, facilitating easier passage through the G1/S checkpoint, abnormal cell cycle progression, and possibly carcinogenesis. Methods We conducted a case-control study involving 396 individuals with IBD. IBD subgroups included CD, UC, and indeterminate colitis (IC). We studied patients with sporadic colorectal cancer (n=75) and patients without gastrointestinal disease as a control group (n=93). We extracted DNA from blood and performed polymerase chain reaction followed by high-performance liquid chromatography to screen for mutations. We confirmed the polymorphism at nucleotide A870G in exon 4. For statistical analysis, we used exact analyses of two-way contingency tables. Power calculations were done and correction for multiple testing was performed by computing the false discovery rate (FDR). Results and discussion Our study had a power of 75% at a 0.05 significance level. A870G SNP allele frequency in the IBD group was 44.8%, compared to 51.6% in the control population. Only the IC group showed a significant association with CCND1 splice site after correction for multiple testing (FDR=0.042). There were no differences between the other IBD groups and controls. Conclusion We found an association between CCND1 A870G SNP and IC group only (p=0.014, FDR=0.042). However, our data do not show an association between CCND1 A870G SNP and CD-associated or UC-associated neoplasia.

T-cell receptor γ: A microsatellite marker for colorectal cancer

Background: T-cell receptor γ (TCR-γ) is involved in maintaining host cell integrity and homeostasis of the human immune system. We hypothesize that polymorphism of the TCR-γ complex may be involved in the pathogenesis of colorectal cancer.Methods: The microsatellite markers D7S1818 and D7S2206 located within the TCR-γ antigen locus on chromosome 7p were amplified by polymerase chain reaction, and genotypes were determined for 22 patients with early onset of colorectal cancer (<60 years old) and for 38 population-based control subjects.Results: Genotype BC of D7S1818 (P=.049) and haplotype AC of D7S1818/D7S2206 (P ≤ .003) were associated with colorectal cancer as compared with the control population (extended Fisher’s exact test).Conclusions: This study identifies a novel genetic and clinical association between TCR-γ and early-onset colorectal cancer. Many young patients do not fulfill the criteria for hereditary colorectal cancer syndromes and are therefore not identified by established screening programs. Markers such as D7S1818 and D7S2206 may become useful in the identification of patients at risk of developing colorectal cancer and permit earlier therapeutic intervention.

Plasma microRNA Profile Differentiates Crohn’s Colitis From Ulcerative Colitis

Abstract Background Inflammatory bowel disease (IBD) is commonly divided into 2 entities: Crohn’s disease (CD) and ulcerative colitis (UC). Differentiating between these entities when dealing with IBD confined to the colon is important, especially when planning surgical treatment. Due to ambiguous histological or endoscopic findings, accurate diagnosis is not possible in up to 15% of cases. The aim of this study was to determine whether plasma microRNAs (miRNAs) can help differentiate Crohn’s colitis (CC) from ulcerative colitis. Methods Patients with isolated CC and with UC were enrolled in our study from January 2010 to May 2016. Peripheral blood was collected, and total RNA was isolated from plasma. Screening was performed for 380 common miRNAs. miRNAs that were differentially expressed between these 2 groups were chosen, and their differential expression was confirmed using single miRNA assays in a larger sample size. A predictive model was generated using these data. Significantly differentially expressed miRNAs were then validated utilizing the predictive model to assess blinded data from the single assays. Results Screening was performed on 8 patients from each group. Seven differentially expressed miRNAs were chosen for single assay confirmation. Two miRNAs (miR-598, miR-642) were consistently different between the patient groups (P = 0.013, P = 0.005). Using blinded data, these 2 miRNAs were validated using the predictive model, achieving an overall accuracy of 75% (95% confidence interval, 40.7–92.9). Conclusions We identified 2 plasma miRNAs that differentiated CC from UC. Our data indicate the promise and feasibility of a plasma miRNA–based assay to distinguish between these 2 conditions.