Fig. 5

CXCL1^EV-dead promotes TNBC growth and lung metastasis in vivo by activating TAM/PD-L1 signaling. A The successful generation of 4 T1/rCXCL1^Flag cells was validated by immunoblotting and immunofluorescence assays. Scale bar: 5 μm. B The difference in CXCL1 content between EV-dead and EV-dead^rCXCL1-Flag was compared by ELISA. EV-dead^rCXCL1-Flag was isolated from the supernatants of apoptotic 4 T1/rCXCL1^Flag cells induced by paclitaxel treatment; n = 3. C, D Peritumoral injection with EV-dead^rCXCL1 (200 μg/20 g weight, q3d) significantly accelerated TNBC growth (C) and lung metastasis (D) compared to that of the EV-dead group (200 μg/20 g weight, q3d); Tumor volume: n = 6; Number of metastatic lesions, n = 3; K-M curves of lung metastasis time, n = 10. Scale bar: 1 cm. E Tumor tissue immunofluorescence experiment showed that flag-tagged CXCL1 (red) from EV-dead^rCXCL1-Flag was predominantly phagocytosed by CD206⁺ macrophages (green) in the TME. Scale bar: 5 μm. F The infiltration levels of CD45⁺/F4/80⁺/CD206⁺ TAMs (up) and CD45⁺/F4/80⁺/PD-L1⁺ TAMs (down) in the TME of mice following treatment with saline, EV-dead, or EV-dead^rCXCL1-Flag; n = 3. G QPCR assay was conducted to investigate the CTC quantity in the peripheral blood of mice following treatment with saline, EV-dead, or EV-dead^rCXCL1-Flag; n = 3. Data are presented as mean ± SD. ^*p < 0.05, ^**p < 0.01