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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+ 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+CD33+HLA-DRlo. 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.

Background The Multiple Endocrine Neoplasia, type 1 (MEN1) locus encodes the nuclear tumor suppressor protein menin. MEN1 mutations frequently cause neuroendocrine tumors (NETs) such as gastrinomas, remarkable for their predominant duodenal location and local metastasis at the time of diagnosis. Diffuse gastrin cell hyperplasia precedes the appearance of MEN1 gastrinomas, which develop within submucosal Brunner’s glands. We show here that loss of menin in enteric glial cells induces gastrin expression. Aim To determine how menin regulates gastrin gene expression and induces the generation of submucosal gastrin-expressing cell hyperplasia. Methods Primary enteric glial cultures were generated from the Villin-Cre:Men1FL/FL:Sst−/− mice with or without inhibition of gastric acid using omeprazole. In addition, primary enteric glial cells from wild type mice were treated with gastrin and were separated into nuclear and cytoplasmic fractions. Forskolin and H89 treatments were used to activate or inhibit protein kinase A activity. Immunoprecipitation with menin or ubiquitin was used to demonstrate posttranslational modification of menin. Primary glial cells were treated with Leptomycin b and MG132 to block nuclear export and proteasome activity, respectively. Results Gfap+ enteric glial cells expressed gastrin de novo through a feedforward PKA-dependent mechanism. Gastrin-induced nuclear export of menin through Cckbr-mediated PKA activation. Once exported menin was ubiquitinated and degraded by the proteasome. Gfap and other enteric glial markers co-localized with gastrin in human duodenal gastrinomas. Conclusion Collectively, these results suggest that MEN1-associated gastrinomas, which develop in the submucosa might arise from enteric glial cells through hormone-dependent PKA signaling that abrogates menin function leading to hypergastrinemia and associated sequelae.

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In colorectal cancer (CRC), APC-mediated induction of unregulated cell growth involves post-translational mechanisms that prevent proteasomal degradation of proto-oncogene β-catenin (CTNNB1) and its eventual translocation to the nucleus. However, about 10 percent of colorectal tumors also exhibit increased CTNNB1 mRNA. Here we show in CRC that increased expression of ZNF148, the gene coding for transcription factor ZBP-89, correlated with reduced patient survival. Tissue arrays showed that ZBP-89 protein was overexpressed in the early stages of CRC. Conditional deletion of Zfp148 in a mouse model of Apc-mediated intestinal polyps demonstrated that ZBP-89 was required for polyp formation due to induction of Ctnnb1 gene expression. ChIP and EMSA identified a ZBP-89 binding site in the proximal promoter of CTNNB1. Recipricolly, siRNA-mediated reduction of CTNNB1 expression also decreased ZBP-89 protein. ChIP identified TCF DNA binding sites in the ZNF148 promoter through which Wnt signaling regulates ZNF148 gene expression. Suppression of either ZNF148 or CTNNB1 reduced colony formation in WNT-dependent, but not WNT-independent cell lines. Therefore, the increase in intracellular β–catenin protein initiated by APC mutations is sustained by ZBP-89-mediated feedforward induction of CTNNB1 mRNA.