Transcription factor-mediated intestinal metaplasia and the role of a shadow enhancer

Barrett's esophagus (BE) and gastric intestinal metaplasia are related premalignant conditions in which areas of human stomach epithelium express mixed gastric and intestinal features. Intestinal transcription factors (TFs) are expressed in both conditions, with unclear causal roles and cis-regulatory mechanisms. Ectopic CDX2 reprogrammed isogenic mouse stomach organoid lines to a hybrid stomach–intestinal state transcriptionally similar to clinical metaplasia; squamous esophageal organoids resisted this CDX2-mediated effect. Reprogramming was associated with induced activity at thousands of previously inaccessible intestine-restricted enhancers, where CDX2 occupied DNA directly. HNF4A, a TF recently implicated in BE pathogenesis, induced weaker intestinalization by binding a novel shadow Cdx2 enhancer and hence activating Cdx2 expression. CRISPR/Cas9-mediated germline deletion of that cis-element demonstrated its requirement in Cdx2 induction and in the resulting activation of intestinal genes in stomach cells. dCas9-conjugated KRAB repression mapped this activity to the shadow enhancer's HNF4A binding site. Altogether, we show extensive but selective recruitment of intestinal enhancers by CDX2 in gastric cells and that HNF4A-mediated ectopic CDX2 expression in the stomach occurs through a conserved shadow cis-element. These findings identify mechanisms for TF-driven intestinal metaplasia and a likely pathogenic TF hierarchy.

Surgical Management of Benign Gastric Tumors: A Review

Benign stomach and duodenal tumors are uncommon. Any component of the stomach epithelium, whether glandular, endocrine, or mesenchymal, can develop benign neoplastic tumors. The majority of people with benign stomach and duodenal tumors are asymptomatic for a long time. When symptoms do appear, they are determined by the tumor's size, location, and comorbidities. Endoscopy, computed tomography, and especially endoscopic ultrasonography results are used diagnose. Clinically, it's difficult to tell the difference between benign and malignant stomach tumors. Even benign tumors can undergo malignant transformation, severe obstructive problems, and bleeding. As a result, aggressive surgical resection of the tumors should be undertaken. Laparoscopic resection has become the first option of many surgeons since the development of minimally invasive surgery. According to previous literature, laparoscopic excision of GIST is safe and effective. In this review we’ll be looking at benign gastric tumors, gastrointestinal stromal tumors (GISTs) and their diagnosis.

Single-minded 2 is required for left-right asymmetric stomach morphogenesis

The morphogenesis of left-right (LR) asymmetry is a critical phase of organogenesis. In the digestive tract, the development of anatomical asymmetry is first evident in the leftward curvature of the stomach. To elucidate the molecular events that shape this archetypal laterality, we performed transcriptome analyses of the left versus right sides of the developing stomach in frog embryos. Besides the known LR gene pitx2, the only gene found to be expressed asymmetrically throughout all stages of curvature was single-minded2 (sim2), a Down Syndrome-related transcription factor and homolog of a Drosophila gene (sim) required for LR asymmetric looping of the fly gut. We demonstrate that sim2 functions downstream of LR patterning cues to regulate key cellular properties and behaviors in the left stomach epithelium that drive asymmetric curvature. Our results reveal unexpected convergent cooption of single-minded genes during the evolution of LR asymmetric morphogenesis, and have implications for dose-dependent roles of laterality factors in non-laterality-related birth defects.

RA10.03: REGENERATING ESOPHAGEAL SQUAMOUS EPITHELIUM FROM SQUAMOUS PROGENITOR CELLS THROUGH BMP2/4 SIGNAL INHIBITION IN MODELS OF BARRETT's ESOPHAGUS: A PROMISING CHEMOPREVENTIVE TREATMENT FOR ESOPHAGEAL ADENOCARCINOMA

Background Barrett's esophagus is a metaplastic condition in which the esophageal normal squamous mucosa is replaced by metaplastic columnar type of epithelium, which is a the result of chronic duodeno-gastric reflux, which causes an inflammatory response. One way to divert the risk of malignant progression of Barrett's esophagus would be by re-establishing squamous epithelium through inhibiting Barrett cells. In earlier studies the SHH-BMP4 pathway has been identified as one of the critical pathways involved in the generation of columnar metaplasia. BMPs are secreted stromal factors for instance involved in development and homeostasis of columnar epithelia. Therefore targeting BMPs to modulate signaling and inhibit columnar cell growth and proliferation could be an attractive approach for diverting cancer risk of metaplastic columnar epithelia such as Barrett's esophagus. Methods We first set out to study BMP signaling through analysis of RNA sequencing to identify which BMPs are involved in Barrett's esophagus and in three different models we investigated the effects of specific BMP inhibition and neo-squamous regeration. We finally investigated the origin of the neo-squamous cells by lineage tracing in one of our models. Results We found that In a transgenic mouse model, conditional knock out of the BMP inhibitor Noggin increased BMP signaling and development of columnar metaplasia arising from multilayered glands glands at the squamo-columnar junction in the stomach (figure…). We demonstrate that inhibiting BMP2 and 4, drives development of squamous epithelium in these glands. In for its effect of epithelial healing in an cryo-ablation model. Additionally, to perform lineage tracing using K5-cre-Tomato-GFP lineage tracing mice to investigate the site of origin of the neo-squamous epithelium. Method: Cryoablation of the stomach epithelium in wild-type and CK5 lineage tracing mice was performed just distal of the squamo-columnar junction and mice were treated with saline or intraperitoneal injections of the BMP inhibitor for 0, 7, 14 and 21 days. The healing process of the ablated area was investigated by histology and immunohistochemistry (IHC) using a panel of both squamous (CK5 and p63) and columnar markers (Villin, CK19). Results: At 21 days post ablation, we observed that the inhibition of BMP4 promoted the re-generation of neo-sqaumous epithelium in the ablated area, while the control group showed re-generation of normal stomach epithelium. IHC showed that the neo-squamous epithelium was positive for the CK5 and p63 squamous markers. Lineage tracing indicated that the squamous cells originated for multilayered glands at the squamo-columnar junction and from the adjacent squamous epithelium (Figure 1). Conclusion Our results demonstrate that inhibition of BMP2/4 after ablation of columnar epithelium at the squamo-columnar junction, promotes development of neo-squamous epithelium from submucosal multi-layered glands residing at the SCJ and adjacent squamous epithelium, at the same time the regeneration of columnar epithelium is inhibited. These pre-clinical findings can be translated to a clinical setting in order to optimize ablative therapies for treatment of BE patients. Disclosure All authors have declared no conflicts of interest.

Morphological Changes in the Upper Part of Digestive Tract in a Case of Experimental Duodenogastric Reflux

Experimental reproduction of duodeno-gastric reflux was performed among Wistar line 28 rats, which were injected with 50 % solution of medical bile by intragastric way. Morphological study had been shown significant structural changes in the gingival tissues, mucous membrane of an esophagus, stomach and duodenum. In the epithelial layer of gingiva and esophagus was observed numerous infringements in a process of differentiation cells, in the stroma was shown phenomena of fibrosis in a papillary layer, microcirculation disorders. In the gastric mucosa had been found out multiple erosions, the glandular cells were increased. It was demonstrated vacuolization of the basal and thorn layers of the stomach epithelium. In the stroma defined phenomena of fibrosis and a dense lymphocyte infiltration with eosinophils. In the duodenum was determined desquamation of a glandular epithelium, superficial erosions of the villi, lympho–histio–plasmocytosis infiltration in a stroma, microvascular disorders. The given experiment demonstrates a role of functional disorders in the pathogenesis of combined pathology in the upper gastrointestinal tract.