Time filter

Source Type

Watford, United Kingdom

Lai C.,Queen Mary, University of London | Robinson J.,Queen Mary, University of London | Clark S.,Polyposis Registry | Stamp G.,Cancer Research UK Research Institute | And 2 more authors.
Journal of Pathology | Year: 2011

Peutz-Jeghers syndrome (PJS) is a rare, inherited disease caused by germline mutation of the LKB1 gene. Patients with PJS develop characteristic polyps in the digestive tract and carry an elevated risk of cancers in multiple organs, including the intestinal tract. While LKB1 is capable of phosphorylating AMPK and regulates the mTOR pathway, it is also known to be a multitasking protein that can influence other cellular processes, including cell polarity. We hypothesized that there may be other biological pathways directly or indirectly affected by the loss of LKB1in PJS and aimed to investigate this possibility through transcriptional profiling of polyps harvested from an Lkb1+/- mouse model of PJS and from PJS patients. We identified alterations in the mRNA level of a wide range of genes, including some that are involved in Wnt signalling ( Wnt5a, Wif1, Dixdc1, Wnt11, Ccnd1, and Ccnd2), although we did not observe nuclear localization of β-catenin in over 93 human PJS intestinal polyps or in 24 gastric polyps from Lkb1+/- mice. Among these genes, WNT5A, a non-canonical and non-transforming Wnt, is consistently up-regulated in both Lkb1+/- mice and human PJS polyps at a high level. We performed in situ hybridization to further define the spatial expression pattern of WNT5A and observed a strong signal in the stroma of mouse and human polyps compared to no or very low expression in the mucosa. Our findings indicate that WNT5A plays an important role in PJS polyposis. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Source

Gupta A.,St. Marks Hospital | Postgate A.J.,Wolfson Unit for Endoscopy | Burling D.,St. Marks Hospital | Ilangovan R.,St. Marks Hospital | And 4 more authors.
American Journal of Roentgenology | Year: 2010

OBJECTIVE. The objective of our study was to assess the utility of MR enterography compared with capsule endoscopy for the detection of small-bowel polyps in patients with Peutz-Jeghers syndrome (PJS). SUBJECTS AND METHODS. Adult patients with PJS scheduled for surveillance capsule endoscopy were prospectively recruited and underwent MR enterography and capsule endoscopy. Polyps > 10 mm were regarded as clinically relevant. When appropriate, large polyps (> 15 mm) were removed at enteroscopy, enabling correlation with MR enterography and capsule endoscopy findings. Interobserver agreement for MR enterography and capsule endoscopy was calculated. Patient comfort, convenience, and test preference were assessed. RESULTS. Nineteen patients (median age, 39.6 years) underwent both procedures. There was no significant difference between techniques for the detection of polyps > 10 mm (18 vs 23 polyps at capsule endoscopy and MR enterography, respectively; p = 0.35) or in the number of patients in whom > 10 mm polyps were detected (eight vs 11 patients at capsule endoscopy and MR enterography, respectively; p = 0.38). However, in three patients, large polyps (> 15 mm) detected on MR enterography were not detected on capsule endoscopy; large polyps were seen in six patients at capsule endoscopy and in nine patients at MR enterography (p = 0.25). Interobserver agreement was high for MR enterography but was only fair for capsule endoscopy (κ = 0.81 and 0.27, respectively). Size assessments of large polyps (> 15 mm) appeared more reproducible with MR enterography than with capsule endoscopy. Patients rated capsule endoscopy as more comfortable than MR enterography. There was no significant difference between the techniques with regard to patient convenience or preference. CONCLUSION. MR enterography is a promising alternative to capsule endoscopy for small-bowel surveillance in adults with PJS. Although our results suggest that capsule endoscopy is more comfortable for the patient, MR enterography may be less prone to missing large polyps and may be more reliable in their size assessment. © American Roentgen Ray Society. Source

Lewis A.,University of Oxford | Segditsas S.,University of Oxford | Deheragoda M.,University College London | Deheragoda M.,Cancer Research UK Research Institute | And 10 more authors.
Gut | Year: 2010

Background and aims: Adenomatous polyposis coli (APC) is a tumour suppressor gene mutated in the germline of patients with familial adenomatous polyposis (FAP) and somatically in most colorectal cancers. APC mutations impair β-catenin degradation, resulting in increased Wnt signalling. The most frequent APC mutation is a codon 1309 truncation that is associated with severe FAP. A previous study compared two mouse models of intestinal tumorigenesis, ApcR850X (Min) and. Apc1322T (1322T), the latter a model of human codon 1309 changes. 1322T mice had more severe polyposis but, surprisingly, these tumours had lower levels of nuclear β-catenin than Min tumours. The consequences of these different β-catenin levels were investigated. Methods: Enterocytes were isolated from 1322T and Min tumours by microdissection and gene expression profiling was performed. Differentially expressed Wnt targets and other stem cell markers were validated using quantitative PCR, in situ hybridisation and immunohistochemistry. Results: As expected, lower nuclear β-catenin levels in 1322T lesions were associated with generally lower levels of Wnt target expression. However, expression of the Wnt target and stem cell marker Lgr5 was significantly higher in 1322T tumours than in Min tumours. Other stem cell markers (Musashi1, Bmi1 and the Wnt target Cd44) were also at higher levels in 1322T tumours. In addition, expression of the Bmp antagonist Gremlin1 was higher in 1322T tumours, together with lower Bmp2 and Bmp4 expression. Conclusions: The severe phenotype caused by truncation of Apc at codon 1322 is associated with an increased number of stem cells. Thus, a submaximal level of Wnt signalling favours the stem cell phenotype and this may promote tumorigenesis. A level of Wnt signalling exists that is too high for optimal tumour growth. Source

Leedham S.J.,University of Oxford | Leedham S.J.,Translational Gastroenterology Unit | Rodenas-Cuadrado P.,University of Oxford | Howarth K.,University of Oxford | And 12 more authors.
Gut | Year: 2013

Objective: Wnt signalling is critical for normal intestinal development and homeostasis. Wnt dysregulation occurs in almost all human and murine intestinal tumours and an optimal but not excessive level of Wnt activation is considered favourable for tumourigenesis. The authors assessed effects of pan-intestinal Wnt activation on tissue homeostasis, taking into account underlying physiological Wnt activity and stem-cell number in each region of the bowel. Design: The authors generated mice that expressed temporally controlled, stabilised β-catenin along the crypt-villus axis throughout the intestines. Physiological Wnt target gene activity was assessed in different regions of normal mouse and human tissue. Human intestinal tumour mutation spectra were analysed. Results: In the mouse, β-catenin stabilisation resulted in a graduated neoplastic response, ranging from dysplastic transformation of the entire epithelium in the proximal small bowel to slightly enlarged crypts of non-dysplastic morphology in the colorectum. In contrast, stem and proliferating cell numbers were increased in all intestinal regions. In the normal mouse and human intestines, stem-cell and Wnt gradients were non-identical, but higher in the small bowel than large bowel in both species. There was also variation in the expression of some Wnt modulators. Human tumour analysis confirmed that different APC mutation spectra are selected in different regions of the bowel. Conclusions: There are variable gradients in stem-cell number, physiological Wnt activity and response to pathologically increased Wnt signalling along the cryptvillus axis and throughout the length of the intestinal tract. The authors propose that this variation influences regional mutation spectra, tumour susceptibility and lesion distribution in mice and humans. Source

Latchford A.R.,Polyposis Registry | Phillips R.K.S.,Polyposis Registry
Familial Cancer | Year: 2011

The two main problems in the management of the gastrointestinal tract in patients with Peutz-Jeghers syndrome (PJS) are the long term cancer risk and managing polyp related complications, such as intussusception and bleeding. In this article we will focus mainly on the clinical management of these problems. We will highlight some of the controversies regarding gastrointestinal PJS polyps, cancer development and cancer risk. We will review the available literature, particularly focusing on clinical data, to provide insights into these controversies. We describe guidelines for the surveillance and management of gastrointestinal polyps in PJS and review the data behind current recommendations. © 2011 Springer Science+Business Media B.V. Source

Discover hidden collaborations