Abstract 919: Identification of stem cells in stomach corpus and antrum

Abstract Gastric cancer is still relatively poorly understood, because of the lack of knowledge on stem cells in stomach. By radio-labeling experiments and electron microscopy, rapidly proliferating stem cells have been suggested in isthmus of both corpus (which is just below pit cell zone) and antrum (which is a quarter above the base) (1). In addition, there have been reports indicating the proliferation capacity under certain conditions in a subset of chief cells present at the base in corpus (2). We reported earlier that 270 bp Runx1 enhancer element (termed aR1) that drives the expression of Runx1 in hematopoietic stem cells (3). We found that eR1 also marks the cells in these three locations of stomach (4). In antrum, the stem cell marker, Lgr5, has been reported to mark the cells at the base of antrum but not in corpus (5). eR1+ and Lgr5+ stem cell in antrum appears to be different. It will be interesting to find out the difference between these two types of stem cells. Transgenic mouse was generated that harbors eR1 linked to heterologous promoter and Cre recombinase (eR1-CreERT2). By treating the mouse with tamoxifen, we showed lineage tracing from eR1+ cells in the isthmus of both corpus and antrum that replenish entire glands. We expressed K-rasG12D in eR1+ cells in isthmus and observed antralization of corpus epithelium that is similar to precancerous lesion in human stomach after H pylori infection. On the other hand, eR1+ chief cells rarely multiply. However, they robustly proliferate after tissue damage or oncogene expression. When K-rasG12D is activated in eR1+ chief cells, they show retrodifferentiation to show SPEM (spasmolytic polypeptide expressing metaplasia) phenotype. eR1+ chief cells appear to be reserve stem cells that can replace cells after tissue damage. We now have capability to activate or inactivate genes of interest in the stomach stem cells. We are examining stepwise carcinogenesis in stomach. From eR1+ cells in isthmus of both corpus and antrum, we are generating organoids. We will describe interesting difference in the properties of organoids generated from eR1+ cells from corpus and those from antrum. <Reference> (1) Karam and Leblond., The Anatomical Record 1993; 236: 259-273. (2) Goldenring et al., Gastroenterology 2011; 138: 2207-2210. (3) Ng et al., Stem Cells 2010; 28: 1869-81. (4) Matsuo et al., Gastroenterology 2016; PMID: 27670082. (5) Barker et al., Cell Stem Cell 2010; 6: 25-36. Citation Format: Junichi Matsuo, Akihiro Yamamura, Khay Guan Yeoh, Motomi Osato, Yoshiaki Ito. Identification of stem cells in stomach corpus and antrum [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 919. doi:10.1158/1538-7445.AM2017-919