Epithelial down-regulation of the miR-200 family in fibrostenosing Crohn's disease is associated with features of epithelial to mesenchymal transition.

Intestinal mesenchymal cells deposit extracellular matrix in fibrotic Crohn's disease (CD). The contribution of epithelial to mesenchymal transition (EMT) to the mesenchymal cell pool in CD fibrosis remains obscure. The miR-200 family regulates fibrosis-related EMT in organs other than the gut.

Separation of Dual Oxidase 2 and Lactoperoxidase Expression in Intestinal Crypts and Species Differences May Limit Hydrogen Peroxide Scavenging During Mucosal Healing in Mice and Humans.

Background: DUOX2 and DUOXA2 form the predominant H2O2-producing system in human colorectal mucosa. Inflammation, hypoxia, and 5-aminosalicylic acid increase H2O2 production, supporting innate defense and mucosal healing. Thiocyanate reacts with H2O2 in the presence of lactoperoxidase (LPO) to form hypothiocyanate (OSCN-), which acts as a biocide and H2O2 scavenging system to reduce damage during inflammation.

Bone morphogenetic protein and Notch signalling crosstalk in poor-prognosis, mesenchymal-subtype colorectal cancer.

The functional role of bone morphogenetic protein (BMP) signalling in colorectal cancer (CRC) is poorly defined, with contradictory results in cancer cell line models reflecting the inherent difficulties of assessing a signalling pathway that is context-dependent and subject to genetic constraints. By assessing the transcriptional response of a diploid human colonic epithelial cell line to BMP ligand stimulation, we generated a prognostic BMP signalling signature, which was applied to multiple CRC datasets to investigate BMP heterogeneity across CRC molecular subtypes. We linked BMP and Notch signalling pathway activity and function in human colonic epithelial cells, and normal and neoplastic tissue.

The miR-200 family is increased in dysplastic lesions in ulcerative colitis patients.

Background: Colorectal cancer (CRC) is a life-threatening complication of ulcerative colitis (UC), and patients are routinely screened for the development of precancerous lesions (dysplasia). However, rates of CRC development in patients with confirmed low-grade dysplasia vary widely between studies, suggesting a large degree of heterogeneity between these lesions that is not detectable macroscopically. A better understanding of the underlying molecular changes that occur in dysplasia will help to identify lesions at higher risk of malignancy.

Remodelling of microRNAs in colorectal cancer by hypoxia alters metabolism profiles and 5-fluorouracil resistance.

Solid tumours have oxygen gradients and areas of near and almost total anoxia. Hypoxia reduces sensitivity to 5-fluorouracil (5-FU)-chemotherapy for colorectal cancer (CRC). MicroRNAs (miRNAs) are hypoxia sensors and were altered consistently in six CRC cell lines (colon cancer: DLD-1, HCT116 and HT29; rectal cancer: HT55, SW837 and VACO4S) maintained in hypoxia (1 and 0.

Familial adenomatous patients with desmoid tumours show increased expression of miR-34a in serum and high levels in tumours.

Familial adenomatous polyposis (FAP) is rare affecting 1 in 10,000 people and a subset (10%) are at risk of myofibroblastic desmoid tumours (DTs) after colectomy to prevent cancer. DTs are a major cause of morbidity and mortality. The absence of markers to monitor progression and a lack of treatment options are significant limitations to clinical management.

Role of Reactive Oxygen Species in the Abrogation of Oxaliplatin Activity by Cetuximab in Colorectal Cancer.

Background: The antibody cetuximab, targeting epidermal growth factor receptor (EGFR), is used to treat metastatic colorectal cancer (mCRC). Clinical trials suggest reduced benefit from the combination of cetuximab with oxaliplatin. The aim of this study was to investigate potential negative interactions between cetuximab and oxaliplatin.

Low Serum Levels of MicroRNA-19 Are Associated with a Stricturing Crohn's Disease Phenotype.

Background: Development of fibrosis and subsequent stricture formation in Crohn's disease (CD) increases morbidity and rates of surgery and reduces patients' quality of life. There are currently no biomarkers of intestinal fibrosis that might allow earlier identification and better management of patients at increased risk of stricture formation.

Methods: MicroRNA profiling of serum from CD patients was used to identify microRNAs associated with stricture formation.

Low-dose TNF augments fracture healing in normal and osteoporotic bone by up-regulating the innate immune response.

The mechanism by which trauma initiates healing remains unclear. Precise understanding of these events may define interventions for accelerating healing that could be translated to the clinical arena. We previously reported that addition of low-dose recombinant human TNF (rhTNF) at the fracture site augmented fracture repair in a murine tibial fracture model.

Aberrant epithelial GREM1 expression initiates colonic tumorigenesis from cells outside the stem cell niche.

Hereditary mixed polyposis syndrome (HMPS) is characterized by the development of mixed-morphology colorectal tumors and is caused by a 40-kb genetic duplication that results in aberrant epithelial expression of the gene encoding mesenchymal bone morphogenetic protein antagonist, GREM1. Here we use HMPS tissue and a mouse model of the disease to show that epithelial GREM1 disrupts homeostatic intestinal morphogen gradients, altering cell fate that is normally determined by position along the vertical epithelial axis. This promotes the persistence and/or reacquisition of stem cell properties in Lgr5-negative progenitor cells that have exited the stem cell niche.

Epidermal growth factor attenuates tubular necrosis following mercuric chloride damage by regeneration of indigenous, not bone marrow-derived cells.

To assess effects of epidermal growth factor (EGF) and pegylated granulocyte colony-stimulating factor (P-GCSF; pegfilgrastim) administration on the cellular origin of renal tubular epithelium regenerating after acute kidney injury initiated by mercuric chloride (HgCl2 ). Female mice were irradiated and male whole bone marrow (BM) was transplanted into them. Six weeks later recipient mice were assigned to one of eight groups: control, P-GCSF+, EGF+, P-GCSF+EGF+, HgCl2 , HgCl2 +P-GCSF+, HgCl2 +EGF+ and HgCl2 +P-GCSF+EGF+.

The stem cell organisation, and the proliferative and gene expression profile of Barrett's epithelium, replicates pyloric-type gastric glands.

Objective: Barrett's oesophagus shows appearances described as 'intestinal metaplasia', in structures called 'crypts' but do not typically display crypt architecture. Here, we investigate their relationship to gastric glands.

Methods: Cell proliferation and migration within Barrett's glands was assessed by Ki67 and iododeoxyuridine (IdU) labelling.

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.

Identifying the origin and phenotype of cells in tumor xenografts.

The growth of human tumor cells transplanted into immunodeficient mice is frequently studied to gain understanding about the way potential drug treatments interfere with growth in vivo. A wide range of methods is available for learning about specific aspects of tumor cell behavior, for example, cells may be administered to follow their ability to grow close to the site of injection which may be at a generic site or one specific to that type of tumor. Some models of metastasis follow the appearance of a tumor mass after intravascular administration of tumor cells; others score remote growth after removal of a primary tumor implanted subcutaneously.

Lineage tracing reveals multipotent stem cells maintain human adenomas and the pattern of clonal expansion in tumor evolution.

The genetic and morphological development of colorectal cancer is a paradigm for tumorigenesis. However, the dynamics of clonal evolution underpinning carcinogenesis remain poorly understood. Here we identify multipotential stem cells within human colorectal adenomas and use methylation patterns of nonexpressed genes to characterize clonal evolution.

A basal gradient of Wnt and stem-cell number influences regional tumour distribution in human and mouse intestinal tracts.

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.

Trefoil factor family peptides in normal and diseased human pancreas.

Objectives: Trefoil factor family (TFF) peptides promote wound healing in the gut. Recent evidence has suggested that TFF3 may be a pancreatic mitogen, an unusual role for TFF peptides. We sought to clarify human pancreatic TFF and mucin expression and performed in vitro experiments to see how pancreatic cell lines respond to TFF3 in particular.

Bone marrow-derived cells contribute to cerulein-induced pancreatic fibrosis in the mouse.

Bone marrow (BM) cells may transdifferentiate into circulating fibrocytes and myofibroblasts in organ fibrosis. In this study, we investigated the contribution and functional roles of BM-derived cells in murine cerulein-induced pancreatic fibrosis. C57/BL6 female mice wild-type (WT) or Col 1α1(r/r) male BM transplant, received supraphysiological doses of cerulein to induce pancreatic fibrosis.

Field cancerization in the intestinal epithelium of patients with Crohn's ileocolitis.

Background & Aims: Tumors that develop in patients with Crohn's disease tend be multifocal, so field cancerization (the replacement of normal cells with nondysplastic but tumorigenic clones) might contribute to intestinal carcinogenesis. We investigated patterns of tumor development from pretumor intestinal cell clones.

Methods: We performed genetic analyses of multiple areas of intestine from 10 patients with Crohn's disease and intestinal neoplasia.

Bone marrow cells in murine colitis: multi-signal analysis confirms pericryptal myofibroblast engraftment without epithelial involvement.

Background: The contribution of bone marrow-derived cells to epithelial tissues in the inflamed gut remains controversial. Recent reports have suggested that cell fusion between bone marrow-derived cells and the intestinal epithelium takes place in inflammatory conditions.

Methods: In attempts to confirm this, we have undertaken gender mis-matched bone marrow (BM) transplants from male Swiss Webster (SWR) mice to B and T cell-deficient female Rag2 KO mice which, 4 weeks later, were given 5% dextran sodium sulphate in drinking water to induce acute colitis.

The C-terminus of Apc does not influence intestinal adenoma development or progression.

Adenomatous polyposis coli (APC ) mutations are found in most colorectal tumours. These mutations are almost always protein-truncating, deleting both central domains that regulate Wnt signalling and C-terminal domains that interact with the cytoskeleton. The importance of Wnt dysregulation for colorectal tumourigenesis is well characterized.

Delta1 expression, cell cycle exit, and commitment to a specific secretory fate coincide within a few hours in the mouse intestinal stem cell system.

The stem cells of the small intestine are multipotent: they give rise, via transit-amplifying cell divisions, to large numbers of columnar absorptive cells mixed with much smaller numbers of three different classes of secretory cells--mucus-secreting goblet cells, hormone-secreting enteroendocrine cells, and bactericide-secreting Paneth cells. Notch signaling is known to control commitment to a secretory fate, but why are the secretory cells such a small fraction of the population, and how does the diversity of secretory cell types arise? Using the mouse as our model organism, we find that secretory cells, and only secretory cells, pass through a phase of strong expression of the Notch ligand Delta1 (Dll1). Onset of this Dll1 expression coincides with a block to further cell division and is followed in much less than a cell cycle time by expression of Neurog3--a marker of enteroendocrine fate--or Gfi1--a marker of goblet or Paneth cell fate.

PHLDA1 expression marks the putative epithelial stem cells and contributes to intestinal tumorigenesis.

Studies employing mouse models have identified crypt base and position +4 cells as strong candidates for intestinal epithelial stem cells. Equivalent cell populations are thought to exist in the human intestine; however robust and specific protein markers are lacking. Here, we show that in the human small and large intestine, PHLDA1 is expressed in discrete crypt base and some position +4 cells.

Severe polyposis in Apc(1322T) mice is associated with submaximal Wnt signalling and increased expression of the stem cell marker Lgr5.

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.