PIGA mutations and glycosylphosphatidylinositol anchor dysregulation in polyposis-associated duodenal tumorigenesis.

The pathogenesis of duodenal tumours in the inherited tumour syndromes Familial Adenomatous Polyposis (FAP) and MUTYH-associated Polyposis (MAP) is poorly understood. This study aimed to identify genes that are significantly mutated in these tumours and to explore the effects of these mutations. Whole exome and whole transcriptome sequencing identified recurrent somatic coding variants of PIGA in 19/70 (27%) FAP and MAP duodenal adenomas, and further confirmed the established driver roles for APC and KRAS. PIGA catalyses the first step in glycosylphosphatidylinositol (GPI) anchor biosynthesis. Flow cytometry of PIGA-mutant adenoma-derived and CRISPR-edited duodenal organoids confirmed loss of GPI anchors in duodenal epithelial cells and transcriptional profiling of duodenal adenomas revealed transcriptional signatures associated with loss of PIGA. Implications: PIGA somatic mutation in duodenal tumours from patients with FAP and MAP and loss of membrane GPI-anchors may present new opportunities for understanding and intervention in duodenal tumorigenesis.

Feasibility and economic assessment of chromocolonoscopy for detection of proximal serrated neoplasia within a population-based colorectal cancer screening programme (CONSCOP): an open-label, randomised controlled non-inferiority trial.

BACKGROUND: Most post-colonoscopy interval colorectal cancers are proximal; serrated polyps are often precursors to these cancers and are considered difficult to detect. We assessed the safety, feasibility, and economic effect of chromocolonoscopy on detection of proximal serrated neoplasia. METHODS: We did an open-label, multicentre, randomised, controlled non-inferiority trial including patients from Bowel Screening Wales centres. Participants who tested positive for faecal occult blood and who were eligible for and considered fit to have colonoscopy (patients with known cases of polyposis syndromes, Lynch syndrome, and chronic inflammatory disease were excluded) were randomly assigned (1:1; with the use of minimisation, stratified by centre with an 80:20 random element) to either standard white light colonoscopy (standard group) or chromocolonoscopy (indigo carmine dye [0·2%]; chromocolonoscopy group) using a secure, internet-based, computerised, randomisation system that used centralised, dynamic allocation. Participants were followed up for 1 year and data from index colonoscopies and associated clearance procedures were analysed. All proximal polyps were reviewed by an expert pathologist panel. The main outcome on which power was based was time taken to perform the colonoscopy procedure, defined as from the time when the scope was inserted to withdrawal from the anus, assessed in the per-protocol population. The non-inferiority margin was 15 min. This trial is complete and is registered with ClinicalTrials.gov, number NCT01972451. FINDINGS: Between Nov 20, 2014, and June 16, 2016, 741 (72%) of 1031 patients screened were eligible and consented: 360 were randomly assigned to white light colonoscopy and 381 to chromocolonoscopy. In the chromocolonoscopy group, the procedure took a mean of 36·8 min (SD 15·0), compared with a mean of 30·6 min (13·7) in the standard group (mean difference 6·3 min [95% CI 4·2-8·4] longer with chromocolonoscopy than in the standard group). The mean difference was within the prespecified non-inferiority margin. Detection rates for proximal serrated lesions were significantly higher in the chromocolonoscopy group than in the control group (45 [12%] of 381 patients vs 23 [6%] of 360 patients; odds ratio 1·96 [95% CI 1·16-3·32]; p=0·012). Serious adverse events (four cases of postpolypectomy bleeding [two in each group], and one case of anxiety and hyperventilation [in the chromocolonoscopy group]), colonoscopy quality measures, comfort scores, and sedation were similar between groups. INTERPRETATION: Chromocolonoscopy is feasible within a population-based colorectal cancer screening programme, is safe, and has significantly increased detection of proximal serrated neoplasia and other polyp types compared with standard colonoscopy. Larger randomised trials of chromocolonoscopy, powered for improved detection of significant serrated polyps and for longer-term follow-up to investigate the effect on reduction of interval cancers within screening populations, are warranted. FUNDING: Health and Care Research Wales (RfPPB-1021).

Lect2 deficiency is characterised by altered cytokine levels and promotion of intestinal tumourigenesis.

Leukocyte cell-derived chemotaxin 2 (Lect2) is a chemokine-like chemotactic factor that has been identified as a downstream target of the Wnt signalling pathway. Whilst the primary function of Lect2 is thought to be in modulating the inflammatory process, it has recently been implicated as a potential inhibitor of the Wnt pathway. Deregulation of the Wnt pathway, often due to loss of the negative regulator APC, is found in ~80% of colorectal cancer (CRC). Here we have used the ApcMin/+Lect2-/- mouse model to characterise the role of Lect2 in Wnt-driven intestinal tumourigenesis. Histopathological, immunohistochemical, PCR and flow cytometry analysis were employed to identify the role of Lect2 in the intestine. The ApcMin/+Lect2-/- mice had a reduced mean survival and a significantly increased number of adenomas in the small intestine with increased severity. Analysis of Lect2 loss indicated it had no effect on the Wnt pathway in the intestine but significant differences were observed in circulating inflammatory markers, CD4+ T cells, and T cell lineage-specification factors. In summary, in the murine intestine loss of Lect2 promotes the initiation and progression of Wnt-driven colorectal cancer. This protection is performed independently of the Wnt signalling pathway and is associated with an altered inflammatory environment during Wnt-driven tumorigenesis.

Mbd2 enables tumourigenesis within the intestine while preventing tumour-promoting inflammation.

Epigenetic regulation plays a key role in the link between inflammation and cancer. Here we examine Mbd2, which mediates epigenetic transcriptional silencing by binding to methylated DNA. In separate studies the Mbd2-/- mouse has been shown (1) to be resistant to intestinal tumourigenesis and (2) to have an enhanced inflammatory/immune response, observations that are inconsistent with the links between inflammation and cancer. To clarify its role in tumourigenesis and inflammation, we used constitutive and conditional models of Mbd2 deletion to explore its epithelial and non-epithelial roles in the intestine. Using a conditional model, we found that suppression of intestinal tumourigenesis is due primarily to the absence of Mbd2 within the epithelia. Next, we demonstrated, using the DSS colitis model, that non-epithelial roles of Mbd2 are key in preventing the transition from acute to tumour-promoting chronic inflammation. Combining models revealed that prior to inflammation the altered Mbd2-/- immune response plays a role in intestinal tumour suppression. However, following inflammation the intestine converts from tumour suppressive to tumour promoting. To summarise, in the intestine the normal function of Mbd2 is exploited by cancer cells to enable tumourigenesis, while in the immune system it plays a key role in preventing tumour-enabling inflammation. Which role is dominant depends on the inflammation status of the intestine. As environmental interactions within the intestine can alter DNA methylation patterns, we propose that Mbd2 plays a key role in determining whether these interactions are anti- or pro-tumourigenic and this makes it a useful new epigenetic model for inflammation-associated carcinogenesis. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Burden and Profile of Somatic Mutation in Duodenal Adenomas from Patients with Familial Adenomatous- and MUTYH-associated Polyposis.

Purpose: Duodenal polyposis and cancer are important causes of morbidity and mortality in familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP). This study aimed to comprehensively characterize somatic genetic changes in FAP and MAP duodenal adenomas to better understand duodenal tumorigenesis in these disorders.Experimental Design: Sixty-nine adenomas were biopsied during endoscopy in 16 FAP and 10 MAP patients with duodenal polyposis. Ten FAP and 10 MAP adenomas and matched blood DNA samples were exome sequenced, 42 further adenomas underwent targeted sequencing, and 47 were studied by array comparative genomic hybridization. Findings in FAP and MAP duodenal adenomas were compared with each other and to the reported mutational landscape in FAP and MAP colorectal adenomas.Results: MAP duodenal adenomas had significantly more protein-changing somatic mutations (P = 0.018), truncating mutations (P = 0.006), and copy number variants (P = 0.005) than FAP duodenal adenomas, even though MAP patients had lower Spigelman stage duodenal polyposis. Fifteen genes were significantly recurrently mutated. Targeted sequencing of APC, KRAS, PTCHD2, and PLCL1 identified further mutations in each of these genes in additional duodenal adenomas. In contrast to MAP and FAP colorectal adenomas, neither exome nor targeted sequencing identified WTX mutations (P = 0.0017).Conclusions: The mutational landscapes in FAP and MAP duodenal adenomas overlapped with, but had significant differences to those reported in colorectal adenomas. The significantly higher burden of somatic mutations in MAP than FAP duodenal adenomas despite lower Spigelman stage disease could increase cancer risk in the context of apparently less severe benign disease. Clin Cancer Res; 23(21); 6721-32. ©2017 AACR.

Challenging diagnostic issues in adenomatous polyps with epithelial misplacement in bowel cancer screening: 5 years' experience of the Bowel Cancer Screening Programme Expert Board.

The diagnostic difficulties of differentiating epithelial misplacement from invasive cancer in colorectal adenomatous polyps have been recognised for many years. Nevertheless, the introduction of population screening in the UK has resulted in extraordinary diagnostic problems. Larger sigmoid colonic adenomatous polyps, which are those most likely to show epithelial misplacement, are specifically selected into such screening programmes, because these polyps are likely to bleed and screening is based on the detection of occult blood. The diagnostic challenges associated with this particular phenomenon have necessitated the institution of an 'Expert Board': this is a review of the first five years of its practice, during which time 256 polyps from 249 patients have been assessed. Indeed, the Expert Board contains three pathologists, because those pathologists do not necessarily agree, and a consensus diagnosis is required to drive appropriate patient management. However, this study has shown substantial levels of agreement between the three Expert Board pathologists, whereby the ultimate diagnosis has been changed, from that of the original referral diagnosis, by the Expert Board for half of all the polyps, in the substantial majority from malignant to benign. In 3% of polyp cases, the Expert Board consensus has been the dual diagnosis of both epithelial misplacement and adenocarcinoma, further illustrating the diagnostic difficulties. The Expert Board of the Bowel Cancer Screening Programme in the UK represents a unique and successful development in response to an extraordinary diagnostic conundrum created by the particular characteristics of bowel cancer screening.

Brachyury identifies a class of enteroendocrine cells in normal human intestinal crypts and colorectal cancer.

Normal homeostasis of adult intestinal epithelium and repair following tissue damage is maintained by a balance of stem and differentiated cells, many of which are still only poorly characterised. Enteroendocrine cells of the gut are a small population of differentiated, secretory cells that are critical for integrating nutrient sensing with metabolic responses, dispersed amongst other epithelial cells. Recent evidence suggests that sub-sets of secretory enteroendocrine cells can act as reserve stem cells. Given the link between cells with stem-like properties and cancer, it is important that we identify factors that might provide a bridge between the two. Here, we identify a sub-set of chromogranin A-positive enteroendocrine cells that are positive for the developmental and cancer-associated transcription factor Brachyury in normal human small intestinal and colonic crypts. Whilst chromogranin A-positive enteroendocrine cells are also Brachyury-positive in colorectal tumours, expression of Brachyury becomes more diffuse in these samples, suggesting a more widespread function in cancer. The finding of the developmental transcription factor Brachyury in normal adult human intestinal crypts may extend the functional complexity of enteroendocrine cells and serves as a platform for assessment of the molecular processes of intestinal homeostasis that underpins our understanding of human health, cancer and aging.

Adenoma development in familial adenomatous polyposis and MUTYH-associated polyposis: somatic landscape and driver genes.

Familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) are inherited disorders associated with multiple colorectal adenomas that lead to a very high risk of colorectal cancer. The somatic mutations that drive adenoma development in these conditions have not been investigated comprehensively. In this study we performed analysis of paired colorectal adenoma and normal tissue DNA from individuals with FAP or MAP, sequencing 14 adenoma whole exomes (eight MAP, six FAP), 55 adenoma targeted exomes (33 MAP, 22 FAP) and germline DNA from each patient, and a further 63 adenomas by capillary sequencing (41 FAP, 22 MAP). With these data we examined the profile of mutated genes, the mutational signatures and the somatic mutation rates, observing significant diversity in the constellations of mutated driver genes in different adenomas, and loss-of-function mutations in WTX (9%; p < 9.99e-06), a gene implicated in regulation of the WNT pathway and p53 acetylation. These data extend our understanding of the early events in colorectal tumourigenesis in the polyposis syndromes.

Assessment of the In Vivo Activity of PI3K and MEK Inhibitors in Genetically Defined Models of Colorectal Cancer.

The objective of tailoring medicines for cancer patients according to the molecular profile of their disease holds great promise for the improvement of cancer therapy. Nevertheless, this approach has been limited, in part, due to the lack of predictive and informative preclinical studies. Herein, we describe an assessment of the therapeutic potential of targeting PI3K/mTOR and MAPK signaling in genetically defined mouse models of colorectal cancer mirroring disease subtypes targeted for novel therapy in the FOCUS4 trial. Our studies demonstrate that dual PI3K/mTOR inhibition is highly effective in invasive adenocarcinoma models characterized by combinatorial mutations in Apc and Pten; Apc and Kras; and Apc, Pten and Kras. MEK inhibition was effective in the combinatorial Apc and Kras setting, but had no impact in either Apc Pten mutants or in Apc Pten Kras triple mutants. Furthermore, we describe the importance of scheduling for combination studies and show that although no additional benefit is gained in Apc Pten mice, combination of PI3K/mTOR and MAPK inhibition leads to an additive benefit in survival in Apc Kras mice and a synergistic increase in survival in Apc Pten Kras mice. This is the first study using robust colorectal cancer genetically engineered mouse models to support the validity of PI3K/mTOR and MEK inhibitors as tailored therapies for colorectal cancer and highlight the potential importance of drug scheduling in the clinic.

High endothelial venules are rare in colorectal cancers but accumulate in extra-tumoral areas with disease progression.

Prolonged patient survival after surgical resection, is associated with a higher cytotoxic and memory T cell density within colorectal cancers (CRC). High endothelial venules (HEVs) are specialized blood vessels present in secondary lymphoid organs (SLO) that allow ingress of naïve and central memory T cells from the blood. It has been proposed that HEVs in tumors might serve as a similar route of entry for lymphocytes into the tumor and result in an improved prognosis. The present study aimed to characterize HEVs and their microenvironment in resected tumors from colorectal cancer patients (n = 62). We observed HEVs in association with lymphoid aggregates in 49 out of 62 patients. However, these HEV+ lymphoid aggregates were largely at the invasive margin of the tumor and although there was an association with lymphocytes and HEVs at the invasive margin (p = 0.002) there was only a very weak association with tumor infiltrating lymphocytes. Indeed, lymphoid aggregates were associated with more advanced disease (Dukes' stage C) and did not indicate a favorable prognosis.

Brg1 loss attenuates aberrant wnt-signalling and prevents wnt-dependent tumourigenesis in the murine small intestine.

Tumourigenesis within the intestine is potently driven by deregulation of the Wnt pathway, a process epigenetically regulated by the chromatin remodelling factor Brg1. We aimed to investigate this interdependency in an in vivo setting and assess the viability of Brg1 as a potential therapeutic target. Using a range of transgenic approaches, we deleted Brg1 in the context of Wnt-activated murine small intestinal epithelium. Pan-epithelial loss of Brg1 using VillinCreERT2 and AhCreERT transgenes attenuated expression of Wnt target genes, including a subset of stem cell-specific genes and suppressed Wnt-driven tumourigenesis improving animal survival. A similar increase in survival was observed when Wnt activation and Brg1 loss were restricted to the Lgr5 expressing intestinal stem cell population. We propose a mechanism whereby Brg1 function is required for aberrant Wnt signalling and ultimately for the maintenance of the tumour initiating cell compartment, such that loss of Brg1 in an Apc-deficient context suppresses adenoma formation. Our results highlight potential therapeutic value of targeting Brg1 and serve as a proof of concept that targeting the cells of origin of cancer may be of therapeutic relevance.

Interleukin-6 signaling drives fibrosis in unresolved inflammation.

Fibrosis in response to tissue damage or persistent inflammation is a pathological hallmark of many chronic degenerative diseases. By using a model of acute peritoneal inflammation, we have examined how repeated inflammatory activation promotes fibrotic tissue injury. In this context, fibrosis was strictly dependent on interleukin-6 (IL-6). Repeat inflammation induced IL-6-mediated T helper 1 (Th1) cell effector commitment and the emergence of STAT1 (signal transducer and activator of transcription-1) activity within the peritoneal membrane. Fibrosis was not observed in mice lacking interferon-γ (IFN-γ), STAT1, or RAG-1. Here, IFN-γ and STAT1 signaling disrupted the turnover of extracellular matrix by metalloproteases. Whereas IL-6-deficient mice resisted fibrosis, transfer of polarized Th1 cells or inhibition of MMP activity reversed this outcome. Thus, IL-6 causes compromised tissue repair by shifting acute inflammation into a more chronic profibrotic state through induction of Th1 cell responses as a consequence of recurrent inflammation.

PTEN loss and KRAS activation leads to the formation of serrated adenomas and metastatic carcinoma in the mouse intestine.

Mutation or loss of the genes PTEN and KRAS have been implicated in human colorectal cancer (CRC), and have been shown to co-occur despite both playing a role in the PI3' kinase (PI3'K) pathway. We investigated the role of these genes in intestinal tumour progression in vivo, using genetically engineered mouse models, with the aim of generating more representative models of human CRC. Intestinal-specific deletion of Pten and activation of an oncogenic allele of Kras was induced in wild-type (WT) mice and mice with a predisposition to adenoma development (Apc(fl/+) ). The animals were euthanized when they became symptomatic of a high tumour burden. Histopathological examination of the tissues was carried out, and immunohistochemistry used to characterize signalling pathway activation. Mutation of Pten and Kras resulted in a significant life-span reduction of mice predisposed to adenomas. Invasive adenocarcinoma was observed in these animals, with evidence of activation of the PI3'K pathway but no metastasis. However, mutation of Pten and Kras in WT animals not predisposed to adenomas led to perturbed homeostasis of the intestinal epithelium and the development of hyperplastic polyps, dysplastic sessile serrated adenomas and metastasizing adenocarcinomas with serrated features. These studies demonstrate synergism between Pten and Kras mutations in intestinal tumour progression, in an autochthonous and immunocompetent murine model, with potential application to preclinical drug testing. In particular, they show that Pten and Kras mutations alone predispose mice to the spectrum of serrated lesions that reflect the serrated pathway of CRC progression in humans.

Cited1 deficiency suppresses intestinal tumorigenesis.

Conditional deletion of Apc in the murine intestine alters crypt-villus architecture and function. This process is accompanied by multiple changes in gene expression, including upregulation of Cited1, whose role in colorectal carcinogenesis is unknown. Here we explore the relevance of Cited1 to intestinal tumorigenesis. We crossed Cited1 null mice with Apc(Min/+) and AhCre(+)Apc(fl/fl) mice and determined the impact of Cited1 deficiency on tumour growth/initiation including tumour multiplicity, cell proliferation, apoptosis and the transcriptome. We show that Cited1 is up-regulated in both human and murine tumours, and that constitutive deficiency of Cited1 increases survival in Apc(Min/+) mice from 230.5 to 515 days. However, paradoxically, Cited1 deficiency accentuated nearly all aspects of the immediate phenotype 4 days after conditional deletion of Apc, including an increase in cell death and enhanced perturbation of differentiation, including of the stem cell compartment. Transcriptome analysis revealed multiple pathway changes, including p53, PI3K and Wnt. The activation of Wnt through Cited1 deficiency correlated with increased transcription of ß-catenin and increased levels of dephosphorylated ß-catenin. Hence, immediately following deletion of Apc, Cited1 normally restrains the Wnt pathway at the level of ß-catenin. Thus deficiency of Cited1 leads to hyper-activation of Wnt signaling and an exaggerated Wnt phenotype including elevated cell death. Cited1 deficiency decreases intestinal tumourigenesis in Apc(Min/+) mice and impacts upon a number of oncogenic signaling pathways, including Wnt. This restraint imposed by Cited1 is consistent with a requirement for Cited1 to constrain Wnt activity to a level commensurate with optimal adenoma formation and maintenance, and provides one mechanism for tumour repression in the absence of Cited1.

Extensive telomere erosion in the initiation of colorectal adenomas and its association with chromosomal instability.

BACKGROUND: Telomere shortening, dysfunction, and fusion may facilitate the acquisition of large-scale genomic rearrangements, driving clonal evolution and tumor progression. The relative contribution that telomere dysfunction and/or APC mutation play in the chromosome instability that occurs during colorectal tumorigenesis is not clear. METHODS: We used high-resolution telomere length and fusion analysis to analyze 85 adenomatous colorectal polyps obtained from 10 patients with familial adenomatous polyposis and a panel of 50 colorectal carcinomas with patient-matched normal colonic mucosa. Telomerase activity was determined using the telomeric repeat amplification protocol. Array-CGH was used to detect large-scale genomic rearrangements. Pearson correlation and Student t test were used, and all statistical tests were two-sided. RESULTS: Despite the presence of telomerase activity, we observed apparent telomere shortening in colorectal polyps that correlated with large-scale genomic rearrangements (P < .0001) but was independent of polyp size and indistinguishable from that observed in colorectal carcinomas (P = .82). We also observed apparent lengthening of telomeres in both polyps and carcinomas. The extensive differences in mean telomere length of up to 4.6kb between patient-matched normal mucosa and polyps were too large to be accounted for by replicative telomere erosion alone. Telomere fusion events were detected in both polyps and carcinomas; the mutational spectrum accompanying fusion was consistent with alternative nonhomologous end joining. CONCLUSIONS: Telomere length distributions observed in colorectal polyps reflect the telomere length composition of the normal originating cells from which clonal growth was initiated. Originating cells containing both short telomeres and APC mutations may give rise to polyps that exhibit short telomeres and are prone to telomere dysfunction, driving genomic instability and progression to malignancy. J Natl Cancer Inst;2013;105:1202-1211.

Interobserver agreement in the reporting of colorectal polyp pathology among bowel cancer screening pathologists in Wales.

AIMS: To assess the interobserver agreement in the reporting of colorectal polyps among histopathologists participating in the Welsh Bowel Cancer Screening (BCS) programme. METHODS AND RESULTS: Twelve benign polyps representative of BCS cases were identified from pathology files and reported by 28 BCS histopathologists using proforma sheets. The level of agreement between the participants and a gold standard was determined using kappa (κ) statistics. A moderate level of agreement was achieved in the reporting of polyp type [κ = 0.45; 95% confidence interval (CI) 0.34-0.59] and adenomatous lesions were distinguished from non-adenomatous lesions in 96% of cases. Substantial agreement was obtained in distinguishing low- and high-grade dysplasias (κ = 0.67; 95% CI 0.50-0.86), but there was only fair agreement in reporting excision margin status (κ = 0.24; 95% CI 0.07-0.43) with frequent use of the 'uncertain' category. Significant issues included categorizing serrated lesions, recognizing focal high-grade dysplasia and epithelial misplacement, and apparent overdiagnosis of villous change in adenomas. CONCLUSIONS: Interobserver variability in some aspects of reporting colorectal polyps by BCS pathologists is suboptimal, with a potential impact upon patient management and the efficient running of the screening service. Approaches to addressing this are discussed.

PTEN loss and KRAS activation cooperate in murine biliary tract malignancies.

Carcinomas of the biliary tract are aggressive malignancies in humans. Loss of the tumour suppressor PTEN has previously been associated with cholangiocarcinoma development in a murine model. Activation of KRAS is reported in up to one-third of human cholangiocarcinomas and 50% of gall bladder carcinomas. In this study we aimed to test the potential interaction between PTEN and KRAS mutation in biliary tract malignancy. We used an inducible Cre-LoxP-based approach to coordinately delete PTEN and activate KRAS within the adult mouse biliary epithelium. We found that activation of KRAS alone has little effect upon biliary epithelium. Loss of PTEN alone results in the development of low-grade neoplastic lesions, following long latency and at low incidence. Combination of both mutations causes rapid development of biliary epithelial proliferative lesions, which progress through dysplasia to invasive carcinoma. We conclude that activation of the PI3'K pathway following loss of PTEN is sufficient to drive slow development of low-grade biliary lesions in mice. In contrast, mutational activation of KRAS does not result in a similar phenotype, despite a prediction that this should activate both the RAF-MEK-ERK and PI3'-kinase pathways. However, mutation of both genes results in rapid tumourigenesis, arguing that PTEN normally functions as a 'brake' on the PI3'-kinase pathway, limiting the influence of KRAS activation. Mutation of both genes creates a 'permissive' environment, allowing the full effects of both mutations to be manifested. These data reveal an in vivo synergy between these mutations and provides a new mouse model of biliary tract malignancy.

A prospective study of the accuracy and concordance between in-situ and postfixation measurements of colorectal polyp size and their potential impact upon surveillance.

OBJECTIVES: To determine the differences between in-situ, prefixation and postfixation colorectal polyp measurements, their clinical impact upon determining adenoma surveillance intervals, and to compare postfixation measurements using three different devices. PATIENTS AND METHODS: A prospective study of 107 colorectal polyps resected from 65 consecutive patients (45 men, 20 women) undergoing colonoscopy as part of the Bowel Cancer Screening Programme was undertaken. The polyps were measured in situ, prefixation (study gold standard) and using three measurement devices (ruler, callipers and magnifying lens) postfixation in formalin. RESULTS: Prefixation ruler measurements were significantly higher than in-situ (P=0.02) and postfixation ruler measurements (P=0.04). No significant difference was observed between in-situ and postfixation ruler measurements (P=0.36), although in-situ measurements were more variable. In-situ measurements also generated more variation in surveillance intervals than postfixation measurements (9.3 vs. 5.6%). No significant difference was seen between measurements obtained by the three different devices postfixation (P=0.89). CONCLUSION: This study provides evidence supporting the use of postfixation polyp size measurements as advised by recent European pathology colorectal cancer screening recommendations. In the absence of a clinically significant difference between measurement devices, we advise the ruler to be used as a standard for postfixation measurements because of its widespread availability.

Conditional disruption of Axin1 leads to development of liver tumors in mice.

BACKGROUND & AIMS: Mutations in components of the Wnt signaling pathway, including ß-catenin and AXIN1, are found in more than 50% of human hepatocellular carcinomas (HCCs). Disruption of Axin1 causes embryonic lethality in mice. We generated mice with conditional disruption of Axin1 to study its function specifically in adult liver. METHODS: Mice with a LoxP-flanked allele of Axin1 were generated by homologous recombination. Mice homozygous for the Axin1fl/fl allele were crossed with AhCre mice; in offspring, Axin1 was disrupted in liver following injection of ß-naphthoflavone (Axin1fl/fl/Cre mice). Liver tissues were collected and analyzed by quantitative real-time polymerase chain reaction and immunoprecipitation, histology, and immunoblot assays. RESULTS: Deletion of Axin1 from livers of adult mice resulted in an acute and persistent increase in hepatocyte cell volume, proliferation, and transcription of genes that induce the G(2)/M transition in the cell cycle and cytokinesis. A subset of Wnt target genes was activated, including Axin2, c-Myc, and cyclin D1. However, loss of Axin1 did not increase nuclear levels of ß-catenin or cause changes in liver zonation that have been associated with loss of the adenomatous polyposis coli (APC) or constitutive activation of ß-catenin. After 1 year, 5 of 9 Axin1fl/fl/Cre mice developed liver tumors with histologic features of HCC. CONCLUSIONS: Hepatocytes from adult mice with conditional disruption of Axin1 in liver have a transcriptional profile that differs from that associated with loss of APC or constitutive activation of ß-catenin. It might be similar to a proliferation profile observed in a subset of human HCCs with mutations in AXIN1. Axin1fl/fl mice could be a useful model of AXIN1-associated tumorigenesis and HCC.

Relative Prognostic Value of Human Epidermal Growth Factor Receptor 2 (HER2) Expression in Operable Oesophagogastric Cancer.

Aims. The aim of this study was to determine the prognostic significance of HER2 receptor expression in operable oesophagogastric adenocarcinoma. Methods. Eighty-five consecutive patients diagnosed with oesophagogastric adenocarcinoma [18 oesophageal (OC), 32 junctional (JC) and 35 gastric (GC)] undergoing potentially curative resection were studied retrospectively. Immunohistochemistry was used to determine HER2 status at endoscopic biopsy and resection specimen. The primary outcome measure was survival. Results. Twenty (24%) patients had HER2 positive tumours which was commoner in JC (14/32, 44% versus 2/18, 11% in OC and 4/35, 11% in GC, P = 0.003). The sensitivity, specificity, positive and negative predictive values of HER2 status at endoscopic biopsy were 56%, 93%, 63%, 91% respectively (weighted Kappa = 0.504, P < 0.0001). Five-year survival in OC HER2 positive negative was 100% and 36% (P = 0.167) compared with 14% and 44% (P = 0.0726) in JC and 50% and 46% (P = 0.942) in GC respectively. Conclusions. Endoscopic biopsy had a high specificity and negative predictive value in determining HER2 status. Patients with JC had a significantly higher rate of HER2 overexpression and this was associated with a nonsignificant poorer survival trend. A larger study is needed to confirm these findings because of the implications for neoadjuvant and adjuvant chemotherapy regimens.