Deciphering of intra‐tumoural heterogeneity and the interplay between metastasis‐associated meta‐program and myofibroblasts in gastric cancer

Abstract Background Gastric cancer (GC) exhibits high heterogeneity that relies on the oncogenic properties of cancer cells and multicellular interactions in the tumour microenvironment. However, the heterogeneity of GC and their molecular characteristics are still largely unexplored. Methods We employed single‐cell and spatial transcriptomics to comprehensively map the intra‐tumoural heterogeneity within GC. Additionally, in vitro experiments, clinical sample analyses, and patient‐derived organoid models (PDOs) were conducted to validate the key interaction patterns between tumor cells and stromal cells. Results Seven robust meta‐programs (MP1–MP7) in GC were defined with distinct biological significance and spatial distributions. MP3 and MP4 were intimately associated with distinct CD8 T cells skewed toward a cytotoxic or exhaustion state, while MP7, characterised by the highest degree of malignancy, harboured an immune lockdown microenvironment around it and spatially associated with myofibroblasts (myCAFs). Notably, we clarified the interplay between the MP7 and myCAFs, where MP7 induces the chemotactic migration of fibroblasts and promoting their transformation into myCAFs via GDF15/TGFBR2, and in turn, myCAFs‐derived RSPO3 up‐regulates EGR1 to promote the transformation to MP7 in GC cells and human PDOs. Ultimately, the accumulation of myCAFs around MP7 led to fewer infiltration of CD8 T cells, resulting an immune‐deprived microenvironment and the diminished efficacy of immunotherapy. Additionally, based on the gene expression signatures of MP7 GC cells, we predicted specific drugs and verified more potent inhibitory effects of Taselisib and Lapatinib for MP7 GC cells than conventional drugs at the same concentration. Conclusion Taken together, these results deepened the understanding of GC heterogeneity and paved the way for novel therapeutic strategies by targeting MP7 GC cells and their interaction loop with myCAFs in GC treatment. Key points Seven robust meta‐programs (MP1‐MP7) were identified in gastric cancer. MP7 was strongly correlated with cancer metastasis and poor survival of gastric cancer patients. MP7 promoted fibroblast transformation into myCAFs via GDF15/TGFBR2, creating an immune lockdown microenvironment. MyCAFs induced MP7 transformation via the RSPO3/EGR1 pathway, promoting gastric cancer cell migration. Taselisib and Lapatinib were potent inhibitors of MP7 GC cells.