Fig. 4

Colon cancer exosome-associated HSP90B1 promotes the formation of a pre-metastatic niche and facilitates liver metastasis. Five-week-old female BALB/c mice (n = 8 per group) were injected with 20 µg of CT-26-shGFP/exo, CT-26-shHSP90B1-1/exo, or CT-26-shHSP90B1-2/exo, or PBS via the tail vein every 3 days. After 3 weeks of exosome treatment, luciferase-labeled CT-26 cells (1 × 10⁶) were injected into the tail vein of each group. On day 21 after tumor cell injection, metastasis in each group was monitored using a small animal in vivo imaging system (A-B), followed by dissection of the livers. Hematoxylin and eosin (HE) staining was used to quantify the number of metastatic nodules in the liver per mouse (C-D). Immunofluorescence staining was then performed to detect the number of M1 macrophages (CD86+/CD11b+) (E-F), M2 macrophages (CD206+/CD11b+) (G-H), and CD8 + T cells (I-J) in the liver tissues. Data were presented as mean ± SEM (B, D, F, H, J). Statistical analyses were performed with one-way ANOVA with Tukey’s test (B, D, F, H, J). Scale bar = 50 μm