干/祖细胞的转化已与多种组织的肿瘤发生相关联，但在胃中，干细胞定位一直较为困难。因此，我们旨在利用多种标记的组合，更好地将癌基因定位于胃干细胞，并了解它们在胃肿瘤发生的初期阶段的行为。通过靶向干/祖细胞生成的胃上皮化生和癌症的鼠模型，并使用重新分析单细胞RNA测序和免疫染色等技术进行分析。利用CRISPR/Cas9进行干细胞分裂的功能研究。通过BrdU追踪分析和有丝分裂纺锤体的取向评估来确定细胞分裂。通过组织学和免疫染色检查患者的胃组织。致癌因素导致小鼠胃中SOX9+祖细胞的扩张。基因系谱追踪和器官培养实验表明，SOX9+胃上皮细胞与SOX2+祖细胞重叠，并包括可以自我更新和分化以生成所有胃上皮细胞的干细胞。此外，在我们的新型小鼠模型中（Sox2-CreERT;Sox9-loxp（66）-rtTA-T2A-Flpo-IRES-loxp（71）;Kras（Frt-STOP-Frt-G12D）;P53R172H）中，SOX9+SOX2+细胞的致癌靶向导致侵袭性胃癌，结合了Cre-loxp和Flippase-Frt遗传重组系统。Sox9 的缺失阻碍了胃祖细胞的扩张并阻止了Kras激活后的肫化。虽然Sox9在主导不对称分裂的组织稳态维持中并不是必需的，但在Kras激活时Sox9的丧失会导致对称细胞分裂降低，并有效地减弱了干/祖细胞的Kras依赖性扩张。同样，在胃癌器官培养中，Sox9的缺失会降低对称细胞分裂、器官培养数量和器官培养大小。在胃癌患者中，SOX9水平高与复发和预后不良相关。SOX9标记胃干细胞并调节有偏向性对称细胞分裂，这似乎是胃干细胞恶性转化所必需的。版权所有©2023 AGA协会，Elsevier公司出版。

Transformation of stem/progenitor cells has been associated with tumorigenesis in multiple tissues, but in the stomach stem cells have been hard to localize. We therefore aimed to use a combination of several markers in order to better target oncogenes to gastric stem cells and understand their behavior in the initial stages of gastric tumorigenesis.Mouse models of gastric metaplasia and cancer by targeting stem/progenitor cells were generated and analyzed with techniques including reanalysis of single cell RNA sequencing and immunostaining. Gastric cancer cell organoids were genetically manipulated with CRISPR/Cas9 for functional studies. Cell division was determined by BrdU chasing assay and the assessment of the orientation of the mitotic spindles. Gastric tissues from patients were examined by histopathology and immunostaining.Oncogenic insults lead to expansion of SOX9+ progenitor cells in the mouse stomach. Genetic lineage tracing and organoid culture studies show that SOX9+ gastric epithelial cells overlap with SOX2+ progenitors and include stem cells that can self-renew and differentiate to generate all gastric epithelial cells. Moreover, oncogenic targeting of SOX9+SOX2+ cells leads to invasive gastric cancer in our novel mouse model (Sox2-CreERT;Sox9-loxp(66)-rtTA-T2A-Flpo-IRES-loxp(71);Kras(Frt-STOP-Frt-G12D);P53R172H) which combines Cre-loxp and Flippase-Frt genetic recombination systems. Sox9 deletion impedes the expansion of gastric progenitor cells and blocks neoplasia following Kras activation. Although Sox9 is not required for maintaining tissue homeostasis where asymmetric division predominates, loss of Sox9 in the setting of Kras activation leads to reduced symmetric cell division and effectively attenuates the Kras-dependent expansion of stem/progenitor cells. Similarly, Sox9 deletion in gastric cancer organoids reduces symmetric cell division, organoid number and organoid size. In patients with gastric cancer, high levels of SOX9 are associated with recurrence and poor prognosis.SOX9 marks gastric stem cells and modulates biased symmetric cell division, which appears to be required for the malignant transformation of gastric stem cells.Copyright © 2023 AGA Institute. Published by Elsevier Inc. All rights reserved.