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AQP5-Expressing Cells Serve as Stem Cells and Cancer Origins in the Mouse and Human Pyloric Stomach

ABSTRACT: Isolating adult stem cells from human stomach epithelia has proven challenging due to a lack of surface markers that are amenable to antibody-based sorting approaches. Here, through comparative expression profiling of mouse Lgr5+ adult stem cells along the GI tract, we identify novel pylorus-specific stem cell markers, including the membrane protein Aqp5. FACS-based isolation of endogenous AQP5+ cells from healthy human pyloric stomach revealed their stem cell identity in organoid assays. Using new Aqp5-driven CreERT2 mouse models to selectively target conditional mutations to the pyloric stem cell compartment in vivo, we establish pyloric stem cells as a major source of Wnt-driven invasive gastric cancer. The new stem cell markers and mouse models described here will be an invaluable resource for deciphering early gastric cancer formation and for isolating and characterizing human stomach stem cells as a prerequisite to potentially exploiting their regenerative medicine potential in the clinic.

ORGANISM(S): Mus musculus

PROVIDER: GSE121803 | GEO | 2019/12/09

REPOSITORIES: GEO

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Project description:The endodermal lining of the adult gastro-intestinal tract harbors stem cells that are responsible for the day-to-day regeneration of the epithelium. Stem cells residing in the pyloric glands of the stomach and in the small intestinal crypts differ in their differentiation program and in the gene repertoire that they express. Both types of stem cells have been shown to grow from single cells into 3D structures (organoids) in vitro. We show that single adult Lgr5-positive stem cells, isolated from small intestinal organoids, require Cdx2 to maintain their intestinal identity and are converted cell-autonomously into pyloric stem cells in the absence of this transcription factor. Clonal descendants of Cdx2null small intestinal stem cells enter the gastric differentiation program instead of producing intestinal derivatives. Conversely, forced expression of Cdx2 in gastric organoids results in their intestinalization. The intestinal genetic program is thus critically dependent on the single transcription factor encoding gene Cdx2. Small intestinal crypts and stomach glands were isolated from Cdx2-/fl / Lgr5-EGFP-CreERT2 mice and cultured for a week in order to generate small intestinal (SI) and stomach (Sto) in vitro organoids. The Lgr5-CreERT2 enzyme activity has been induced by overnight 4-hydroxytamoxifen induction. Tamoxifen treated and untreated Lgr5-EGFPhi SI and Sto stem cells were FACS sorted and seeded back into ENRWfg (Sto med) culture conditions in order to generate Cdx2-/fl small intestinal (Control SI), Cdx2null small intestinal (Cdx2null SI) and Cdx2-/fl stomach (Control Sto) clonal organoids. Cdx2-/fl SI organoids and Cdx2-/fl Sto organoids have been also cultured in ENR (SI med) to induce differentiation. After some passages of clonal organoid expansion, RNA was isolated from Control SI, Cdx2null SI and Control Sto Lgr5-EGFPhi FACS sorted stem cell populations and from smal intestinal and stomach organoids cultured in different conditions and hybridized on Affymetrix Mouse Gene ST 1.1 arrays.

Project description:Intraductal Papillary Mucinous Neoplasms (IPMNs) of the pancreas are cyst-like precursor lesions that give rise to 25% of pancreatic ductal adenocarcinomas (PDAC). While ~90% of cases are diagnosed before cancer forms, metrics and markers by which to determine if an IPMN will progress are currently lacking. Overall, 96% of IPMNs harbor KRAS (~80%) and/or GNAS (~66%) driver mutations and IPMN may be classified as either gastric, intestinal, or pancreatobiliary type. Recently, we identified a shared program of pyloric type metaplasia between pancreatic and gastric injury. Here, we combined immunostaining, RNA-sequencing, molecular biology, and analysis of patient samples to identify major drivers of this program in IPMN. Methods Single cell RNA-sequencing datasets of human IPMN were assayed for markers of pyloric-type metaplasia. 37 IPMN patient samples were immunostained using MxIHC for MUC5AC, CD44v9, and AQP5. KrasG12D and GnasR201C expression was modified in IPMN cell lines to identify transcriptomic programs driven by each oncogene, and in combination. Gene sets were compared to murine and human gastric cell types. Transcriptomic drivers were identified and manipulated in vitro. Candidate driver expression was evaluated by immunostaining of patient IPMN and graded. Results Analysis of published bulk and scRNA-seq IPMN datasets revealed expression of previously described markers of pyloric type metaplasia. Marker expression was confirmed in patient samples. Manipulation of KrasG12D and GnasR201C expression in IPMN cell lines identified the relative contributions of each oncogene to this gastric phenotype. Regulon analysis suggests that transcription factors SPDEF, CREB3L1, and CREB3L4 amplify this program in response to GnasR201C expression. All transcription factors were expressed in patient IPMN samples. Conclusions In response to oncogenic mutation(s), IPMN form in the pancreas and express markers of pyloric type metaplasia. KrasG12D and GnasR201C expression drive this program through independent and synergistic mechanisms that result in amplified expression of mucins and gastrokines, consistent with the phenotype identified in vivo.

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