A Point Mutation R122C in RUNX3 Promotes the Expansion of Isthmus Stem Cells and Inhibits Their Differentiation in the Stomach

• Published in: Cellular and molecular gastroenterology and hepatology Vol. 13; no. 5; pp. 1317 - 1345
• Main Authors: Douchi, Daisuke, Yamamura, Akihiro, Matsuo, Junichi, Lee, Jung-Won, Nuttonmanit, Napat, Melissa Lim, Yi Hui, Suda, Kazuto, Shimura, Mitsuhiro, Chen, Sabirah, Pang, ShuChin, Kohu, Kazuyoshi, Kaneko, Mari, Kiyonari, Hiroshi, Kaneda, Atsushi, Yoshida, Hideyuki, Taniuchi, Ichiro, Osato, Motomi, Yang, Henry, Unno, Michiaki, Bok-Yan So, Jimmy, Yeoh, Khay Guan, Chuang, Linda Shyue Huey, Bae, Suk-Chul, Ito, Yoshiaki
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2022; Elsevier
• Subjects: Animals; Carcinogenesis - pathology; Core Binding Factor Alpha 3 Subunit - genetics; Enhanced Stem Cell Activity; Gastric Carcinogenesis; Gastric Mucosa; Isthmus; Metaplasia - genetics; Metaplasia - pathology; Mice; Original Research; Point Mutation; Precancerous Conditions - pathology; Preneoplastic State; Stem Cells - metabolism; Stem/Progenitor Cell; Stomach Neoplasms - pathology; pRb; EpCAM; Preneoplastic State; mRNA; Gastric Carcinogenesis; IFN; DMEM; RNA-seq; CDX; IB; TGF-β; Muc; qPCR; Sox9; WNT; IF; WT; Iqgap3; ISH; PBS; BRD2; IL; SPEM; GIF; TBST; GSEA; GSII; RUNX3; R-point; STAT; TNF-α; Enhanced Stem Cell Activity; TFF2; Isthmus; KRAS; Stem/Progenitor Cell; ATP; DPBS; MCM2
• ISSN: 2352-345X; 2352-345X
• DOI: 10.1016/j.jcmgh.2022.01.010

RUNX transcription factors play pivotal roles in embryonic development and neoplasia. We previously identified the single missense mutation R122C in RUNX3 from human gastric cancer. However, how RUNX3R122C mutation disrupts stem cell homeostasis and promotes gastric carcinogenesis remained unclear. To understand the oncogenic nature of this mutation in vivo, we generated the RUNX3R122C knock-in mice. Stomach tissues were harvested, followed by histologic and immunofluorescence staining, organoid culture, flow cytometry to isolate gastric corpus isthmus and nonisthmus epithelial cells, and RNA extraction for transcriptomic analysis. The corpus tissue of RUNX3R122C/R122C homozygous mice showed a precancerous phenotype such as spasmolytic polypeptide-expressing metaplasia. We observed mucous neck cell hyperplasia; massive reduction of pit, parietal, and chief cell populations; as well as a dramatic increase in the number of rapidly proliferating isthmus stem/progenitor cells in the corpus of RUNX3R122C/R122C mice. Transcriptomic analyses of the isolated epithelial cells showed that the cell-cycle–related MYC target gene signature was enriched in the corpus epithelial cells of RUNX3R122C/R122C mice compared with the wild-type corpus. Mechanistically, RUNX3R122C mutant protein disrupted the regulation of the restriction point where cells decide to enter either a proliferative or quiescent state, thereby driving stem cell expansion and limiting the ability of cells to terminally differentiate. RUNX3R122C missense mutation is associated with the continuous cycling of isthmus stem/progenitor cells, maturation arrest, and development of a precancerous state. This work highlights the importance of RUNX3 in the prevention of metaplasia and gastric cancer.