Gastric Mixed Neuroendocrine-Non-neuroendocrine Neoplasms Develop from POU2F3+ Multipotent Progenitors.

Gastric mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are aggressive malignancies that exhibit complex cellular heterogeneity driven by the dual lineages. The dismal patient survival rates highlight the need to elucidate the cellular origin of gastric MiNENs and the key regulatory mechanisms to develop improved treatment strategies. Here, we identified a gastric POU2F3+epithelial population as a potential cell of origin for gastric MiNENs. Lineage tracing and single-cell RNA sequencing further identified that POU2F3+ cells include three distinct subpopulations with divergent differentiation trajectories: progenitor cells (SOX2+SOX9+), tuft cells (POU2F3+DCLK1+), and neuroendocrine cells (SYP+CHGA+). Combined Rb1/Trp53 deletion and MYC overexpression in POU2F3+ epithelial cells (Pou2f3-CreERT; Rb1fl/fl; Trp53fl/fl; LSL-MycT58A) led to the rapid development of gastric MiNENs containing both neuroendocrine and non-neuroendocrine lesions, recapitulating human gastric MiNENs pathology. Transcription factor activity analysis and spatial transcriptomics revealed SOX2 and SOX9 as critical regulators driving subpopulation specification, with SOX2 and SOX9 being enriched in dysplasia and adenocarcinoma, respectively. Bulk RNA sequencing further showed increased expression of CXCL5 in gastric MiNENs, and inhibition of CXCL5 reduced the growth of tumor organoids and xenografts in mouse models. Together these findings offer a physiologically relevant model for studying gastric MiNENs and identify CXCL5 as a potential therapeutic target for this heterogeneous cancer.