IRF-1 is essential for IL-15 production after radiation in Piezo2 KO tumors. (A) The expression of IRF-1 from nuclear and cytoplasm of WT and Piezo2^−/− MC38 by 60 h after IR treatment was shown from three independent experiments. (B) C57BL/6 were transplanted subcutaneously with 2 × 10⁶ WT and Piezo2^−/− MC38-tdTomato cells. Tumors were treated locally with one fraction of 18-Gy IR. On day 5 after radiation, IRF-1 expression in MC38-tdTomato⁺ cells was analyzed by flow cytometry. Representative data of IRF-1 expression (left) and quantification analysis (right) in irradiated WT and Piezo2^−/− MC38 tumors were shown from two independent experiments (n = 3–5 mice per group). (C) At 60 h after IR, IL-15 expression in WT, Piezo2^−/−, and Piezo2^−/−IRF-1^−/− B16F1 tumor cells was shown from three independent experiments. (D) The IL-15 expression in WT, Piezo2^−/−, and Piezo2^−/−IRF-1^−/− MC38 tumor cells by 60 h upon radiation treatment was shown from three independent experiments. (E) The IL-15 expression in CD45⁻ cells from irradiated WT, Piezo2^−/−, and Piezo2^−/−IRF-1^−/− MC38 tumors on day 14 after IR was represented from two independent experiments (n = 4–5 mice per group). (F) C57BL/6 were transplanted subcutaneously with 2 × 10⁶ WT, Piezo2^−/−, and Piezo2^−/−IRF-1^−/− B16F1 cells. Tumors were treated locally with one fraction of 18-Gy IR. The tumor growth curve was shown from two independent experiments (n = 4–6 mice per group). (G) Representative data and quantification of the percentage of PD-1⁺ in CD8⁺ T cells from irradiated WT or Piezo2^−/− MC38 tumors with or without IRF-1 on day 14 after IR were shown from two independent experiments (n = 4 mice per group). (H) Representative data and quantification of the percentage of TCF-1⁺ in CD8⁺ T cells from irradiated WT or Piezo2^−/− MC38 tumors with or without IRF-1 on day 14 after IR were shown from two independent experiments (n = 5–6 mice per group). (I) Representative data and quantification of the percentage of CD62L⁺ in CD8⁺ T cells from irradiated WT or Piezo2^−/− MC38 tumors with or without IRF-1 were shown from two independent experiments (n = 3–4 mice per group). Data were represented as means ± SEM. Statistical analysis was performed by one-way ANOVA with multiple comparison tests (A–E and G–I), and statistical analysis was calculated by two-way ANOVA with multiple comparison tests (F). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns, no significant difference. Source data are available for this figure: SourceData F4.