Fig 1: Molecular mechanisms of GC growth and metastasis involving CAFs and TREM2+LAM.The tumor microenvironment (TME) is illustrated as a dynamic interface involving cancer-associated fibroblasts (CAFs), lipid-associated macrophages (TREM2+LAM), CD8+ T cells, and tumor cells. CAFs secrete CXCL12, which interacts with CXCR4 expressed on TREM2+LAM, promoting their immunosuppressive phenotype via lipid metabolism-related factors (FABP4/5). TREM2+LAM express CD206 and inhibit CD8+ T cell activity by reducing TNF-α secretion, creating an immunosuppressive microenvironment. This interaction enhances tumor proliferation, migration, invasion, and resistance to apoptosis. Metastatic dissemination to secondary sites, such as the lungs, is facilitated by these TME-driven processes. The diagram emphasizes the CXCL12-CXCR4 axis as a critical mediator in CAF and TREM2+LAM crosstalk.
Fig 2: Effects of the CXCL12/CXCR4 axis expression in CAFs on GC cell proliferation, migration, invasion, and apoptosis.A ELISA was performed to detect the concentrations of the cytokines IL-6 and CD206, as well as the chemokine CXCL12 in the cell culture supernatant after M0 differentiation into TAM and MRC-5 into CAF induction; B Typical morphological changes of M0 macrophages co-cultured with CAFs were observed after H&E staining (scale bar: 25 μm); C RT-qPCR was conducted to assess the mRNA expression levels of IL-6 and CD206, markers for M1 and M2 macrophages, respectively; D ELISA was used to measure the concentrations of CXCL12 and CXCR4 in the cell culture supernatant between the CXCL12-neutralized group and the control group; E, F Cell viability and proliferation changes were examined by CCK-8 and colony formation assays; G–I Migration and invasion abilities of the different groups were evaluated by scratch assay and Transwell assay; J Flow cytometry analysis depicted the occurrence of apoptosis in each group, with statistical data on early and late apoptosis presented in the corresponding graphs. Data are expressed as mean ± standard deviation and intergroup comparisons were made using unpaired t-tests. * indicates P < 0.05, ** indicates P < 0.01, and ns denotes no statistical difference between the two groups; * represents the significance level. Cell experiments were repeated three times.
Fig 3: Impact of the CXC12/CXCR4 axis on tumor growth and metastasis in vivo.A–C Comparative analysis and quantitative assessment of tumor size and weight in xenograft tumors from each group (n = 8); D Evaluation of CD3 and CD8 expression in each group by immunohistochemical staining (scale bar: 50 μm); E Protein expression levels of Trem2, Cxcl12, and Cxcr4 in each group analyzed by Western blot; F Effects of GC metastasis on lung tissue in each group and quantitative analysis of metastatic nodules; G Histological changes in lung metastatic nodules evaluated by H&E staining and immunohistochemical staining for CD31 and CD206 (scale bar: 100 μm). Data are presented as mean ± standard deviation and intergroup comparisons were performed using unpaired t-tests. * denotes P < 0.05 for comparison between two groups, ** denotes P < 0.01, *** denotes P < 0.001, and ns indicates no statistical difference between the two groups. Statistical significance is indicated by *. Each group consists of 8 nude mice.
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