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ObjectivesAlterations in 5-hydroxytryptamine (5-HT) signaling have been implicated as a factor contributing to the altered bowel habit of irritable bowel syndrome (IBS) patients. Tryptophan hydroxylase 1 (TPH1) is the rate-limiting enzyme in enterochromaffin cell 5-HT biosynthesis. We hypothesized that genetic variants affecting TPH1 gene expression might alter intestinal 5-HT bioavailability and subsequently the propensity for distinct bowel habit subtypes in IBS. In this study, we assessed the only common TPH1 proximal promoter variant (-347C/A; rs7130929) and its association with bowel habit predominance in IBS.MethodsElectrophoretic mobility shift assays were performed to assess whether the -347C/A-allele variant affects the DNA binding of nuclear factors. Genotype distribution was determined for 422 IBS patients subtyped using the Rome III criteria and for 495 healthy controls recruited from two university medical centers. Association with bowel habit was tested using a multinomial logistic regression model controlling for race, anxiety, depression, and study site.ResultsEarly growth response factor 1 (EGR-1) bound with higher affinity to a site comprising the minor A-allele of single-nucleotide polymorphism (SNP) -347C/A. TPH1 genotype frequencies did not differ between IBS patients and controls overall. The CC genotype was more prevalent in the IBS-D subtype (47%) than in the IBS-C (25%) and IBS-M (37%) subtypes (P=0.039) after adjusting for race and other covariates. Colonic biopsies from a small cohort of IBS patients from one center were tested for higher TPH1 mRNA expression in samples with CC compared with the CA genotype, but the results did not reach statistical significance.ConclusionsThe TPH1 promoter SNP -347C/A differentially binds EGR-1 and correlates with IBS bowel habit subtypes and possibly colonic TPH1 expression consistent with its role in modulating intestinal 5-HT signaling.

Introduction: MDSCs express SCHLAFEN 4 (SLFN4) in Helicobacter-infected stomachs coincident with spasmolytic polypeptide-expressing metaplasia (SPEM), a precursor of gastric cancer. We aimed to characterize SLFN4+ cell identity and the role of Slfn4 in these cells. Methods: Single-cell RNA sequencing was performed on immune cells sorted from PBMCs and stomachs prepared from uninfected and 6-month H. felis-infected mice. Knockdown of Slfn4 by siRNA or PDE5/6 inhibition by sildenafil were performed in vitro. Intracellular ATP/GTP levels and GTPase activity of immunoprecipitated Slfn4 complexes were measured using the GTPase-Glo assay kit. The intracellular level of ROS was quantified by the DCF-DA fluorescent staining, and apoptosis was determined by cleaved Caspase-3 and Annexin V expression. Gli1CreERT2 x Slfn4fl/fl mice were generated and infected with H. felis. Sildenafil was administered twice over 2 weeks by gavaging H. felis infected mice ~4 months after inoculation once SPEM had developed. Results: Slfn4 was highly induced in both monocytic and granulocytic MDSCs from infected stomachs. Both Slfn4+-MDSC populations exhibited strong transcriptional signatures for type-I interferon responsive GTPases and exhibited T cell suppressor function. SLFN4-containing protein complexes immunoprecipitated from myeloid cell cultures treated with IFNa exhibited GTPase activity. Knocking down Slfn4 or PDE5/6 inhibition with sildenafil blocked IFNa induction of GTP, SLFN4 and NOS2. Moreover, IFNa induction of Slfn+-MDSC function was inhibited by inducing their reactive oxygen species (ROS) production and apoptosis through protein kinase G activation. Accordingly, in vivo disruption of Slfn4 in Gli1CreERT2 x Slfn4fl/fl mice or pharmacologic inhibition by sildenafil after Helicobacter infection also suppressed SLFN4 and NOS2, reversed T cell suppression and mitigated SPEM development. Conclusion: Taken together, SLFN4 regulates the activity of the GTPase pathway in MDSCs and precludes these cells from succumbing to the massive ROS generation when they acquire MDSC function. [ABSTRACT FROM AUTHOR]

Chronic Helicobacter pylori infection triggers neoplastic transformation of the gastric mucosa in a small subset of patients, but the risk factors that induce progression to gastric metaplasia have not been identified. Prior to cancer development, the oxyntic gastric glands atrophy and are replaced by metaplastic cells in response to chronic gastritis. Previously, we identified schlafen 4 (Slfn4) as a GLI1 target gene and myeloid differentiation factor that correlates with spasmolytic polypeptide-expressing metaplasia (SPEM) in mice. Here, we tested the hypothesis that migration of SLFN4-expressing cells from the bone marrow to peripheral organs predicts preneoplastic changes in the gastric microenvironment. Lineage tracing in Helicobacter-infected Slfn4 reporter mice revealed that SLFN4+ cells migrated to the stomach, where they exhibited myeloid-derived suppressor cell (MDSC) markers and acquired the ability to inhibit T cell proliferation. [SLFN4.sup.+] MDSCs were not observed in infected GLI1-deficient mice. Overexpression of sonic hedgehog ligand (SHH) in infected WT mice accelerated the appearance of SLFN4+ MDSCs in the gastric corpus. Similarly, in the stomachs of H. pylori-infected patients, the human SLFN4 ortholog SLFN12L colocalized to cells that expressed MDSC surface markers [CD15.sup.+][CD33.sup.+]HLA-[DR.sup.lo]. Together, these results indicate that SLFN4 marks a GLI1-dependent population of MDSCs that predict a shift in the gastric mucosa to a metaplastic phenotype., Introduction Helicobacter pylori infection induces chronic inflammation in the stomach, which eventually leads to atrophy of the acid-producing glands, metaplasia, dysplasia, and then gastric cancer in some infected patients (1-3). [...]

Small intestinal neuroendocrine tumors (SI-NETs) are serotonin-secreting well-differentiated neuroendocrine tumors of putative enterochromaffin (EC) cell origin. However, EC cell-derived tumorigenesis remains poorly understood. Here, we examined whether the gain of Myc and the loss of RB1 and Trp53 function in EC cells result in SI-NET using tryptophan hydroxylase 1 (TPH1) Cre-ERT2-driven RB1fl Trp53fl MycLSL (RPM) mice. TPH1-Cre-induced gain of Myc and loss of RB1 and Trp53 function resulted in endocrine or neuronal tumors in pancreas, lung, enteric neurons, and brain. Lineage tracing indicated that the cellular origin for these tumors was TPH1-expressing neuroendocrine, neuronal, or their precursor cells in these organs. However, despite that TPH1 is most highly expressed in EC cells of the small intestine, we observed no incidence of EC cell tumors. Instead, the tumor of epithelial cell origin in the intestine was exclusively nonendocrine adenocarcinoma, suggesting dedifferentiation of EC cells into intestinal stem cells (ISCs) as a cellular mechanism. Furthermore, ex vivo organoid studies indicated that loss of functions of Rb1 and Trp53 accelerated dedifferentiation of EC cells that were susceptible to apoptosis with expression of activated MycT58A, suggesting that the rare dedifferentiating cells escaping cell death went on to develop adenocarcinomas. Lineage tracing demonstrated that EC cells in the small intestine were short-lived compared with neuroendocrine or neuronal cells in other organs. In contrast, EC cell-derived ISCs were long-lasting and actively cycling and thus susceptible to transformation. These results suggest that tissue- and cell-specific properties of EC cells such as rapid cell turnover and homeostatic dedifferentiation, affect the fate and rate of tumorigenesis induced by genetic alterations and provide important insights into EC cell-derived tumorigenesis. [ABSTRACT FROM AUTHOR]

Gastrointestinal cancers continue to account for a disproportionately large percentage of annual cancer deaths in the United States. Advancements in miniature imaging technology combined with a need for precise and thorough tumor detection in gastrointestinal cancer screenings fuel the demand for new, small-scale, and low-cost methods of localization and margin identification with improved accuracy. Here, we report the development of a miniaturized, chip-on-tip, multispectral, fluorescence imaging probe designed for compatibility with a gastroscope working channel with the aim of detecting cancerous lesions in point-of-care endoscopy of the gastrointestinal lumen. Preclinical testing has confirmed fluorescence sensitivity and supports that this miniature probe can locate structures of interest via detection of fluorescence emission from exogenous contrast agents. This work demonstrates the design and preliminary performance evaluation of a miniaturized, single-use, chip-on-tip fluorescence imaging system, capable of detecting multiplexed fluorophores, and devised for deployment via the accessory channel of a standard gastroscope. [ABSTRACT FROM AUTHOR]

Menin is a tumour suppressor protein whose loss or inactivation causes multiple endocrine neoplasia 1 (MEN1), a hereditary autosomal dominant tumour syndrome that is characterized by tumorigenesis in multiple endocrine organs (1). Menin interacts with many proteins and is involved in a variety of cellular processes (2-8). Menin binds the JUN family transcription factor JUND and inhibits its transcriptional activity (2,9). Several MEN1 missense mutations disrupt the menin-JUND interaction, suggesting a correlation between the tumour-suppressor function of menin and its suppression of JUND-activated transcription (2,10). Menin also interacts with mixed lineage leukaemia protein 1 (MLL1), a histone H3 lysine 4 methyl-transferase, and functions as an oncogenic cofactor to upregulate gene transcription and promote MLL1-fusion-protein-induced leukaemogenesis (5,7,11,12). A recent report on the tethering of MLL1 to chromatin binding factor lens epithelium-derived growth factor (LEDGF) by menin indicates that menin is a molecular adaptor coordinating the functions of multiple proteins (13). Despite its importance, how menin interacts with many distinct partners and regulates their functions remains poorly understood. Here we present the crystal structures of human menin in its free form and in complexes with MLL1 or with JUND, or with an MLL1-LEDGF heterodimer. These structures show that menin contains a deep pocket that binds short peptides of MLL1 or JUND in the same manner, but that it can have opposite effects on transcription. The menin-JUND interaction blocks JUN N-terminal kinase (JNK)-mediated JUND phosphorylation and suppresses JUND-induced transcription. In contrast, menin promotes gene transcription by binding the transcription activator MLL1 through the peptide pocket while still interacting with the chromatin-anchoring protein LEDGF at a distinct surface formed by both menin and MLL1., The amino-terminal region of MLL1 interacts with menin (12,14,15). Isothermal titration calorimetry measurements showed that the menin-binding motif (residues 6-25) of MLL1 (MLL1MBM) is necessary and sufficient for menin binding [...]

Chronic inflammation in the stomach induces cellular transformation and gastric cancer primarily in the distal stomach or antrum. In this issue of the JCI, a study in mice by Ernst et al. provides new insight into the role of IL-11 and its glycoprotein 130 (gp130) receptor in inflammation-associated gastric epithelial cell oncogenic transformation, which they show is mediated by and dependent on increased activation of Stat3 and, to a lesser extent, Stat1 (see the related article beginning on page 1727). Prior studies from this group have shown that Stat3 hyperactivity stimulates the TGF-[beta] inhibitor Smad7. Collectively, the studies suggest that an important pathway of oncogenic transformation in the stomach is through suppression of growth inhibitory signals, such as members of the TGF-[beta] family, that originate from the stroma., Cancer originates in a variety of different tissues that are susceptible to chronic inflammatory conditions. In the stomach, the phenotypic steps leading from chronic inflammation (gastritis) to distal gastric cancer [...]

The gastrointestinal (GI) tract is composed of a diverse set of organs that together receive extracorporeal nutrition and convert it to energy substrates and cellular building blocks. In the process, [...]