Fig. 1
Estrogen promotes brain metastasis by activating microglia in vivo. a Scheme of the experimental design is shown in the left panel. The OVX, OVX + E2, and OVX + E2 + tamoxifen (Tamo) groups received the OVX treatment 1 week before the tumor injection. 231BrM (6 × 105 cells) were intracardially injected into nude mice (n = 9) followed by administration of E2 pellet. After 3 days of intracardiac transplantation of the tumor cells, mice in tamoxifen group received tamoxifen (20 mg/kg) treatment by i.p. injection every 3 days till day 32. Right upper panel: Representative BLI images of mice from each experimental group (vehicle alone or E2, OVX, OVX + E2, Tamo or OVX + E2 + Tamo treatment). Right lower panel: Representative images of total ex vivo photon flux of brain metastatic lesions measured by BLI at the end point (Day 32). b Percentage of brain metastasis of breast cancer in nude mice with or without estrogen and/or tamoxifen treatment. Chi-square test, *: p 0.05; ***: p0.001. c Quantitative data of in vivo brain metastasis of breast cancer. Two-way ANOVA, **: p < 0.01; ***: p < 0.001 versus the opposite group; ##: p < 0.01. ###: p < 0.001versus related Veh group. (n = 9). d Quantitative data of ex vivo signals in the brain at the endpoint. One-way ANOVA, *: p < 0.05; ***: p < 0.001. (n = 9). e and f Metastatic brain tumors from (a) were isolated and examined by flow cytometry for M1 (F4/80+/Tmem119+) and M2 (CD206+/Tmem119+) microglial polarization. One-way ANOVA, **: p < 0.01; ***: p < 0.001. (n = 4). g Representative images of immunohistochemical analysis for CD206+ (M2 microglia) and CD45+ (macrophage) cells in the brain metastatic lesions of pre-menopause (n = 7) and post-menopause (n = 7) breast cancer patients. Scale bar: 200 μm. Right panels: CD206 and CD14 staining cells were quantified in premenopausal and postmenopausal patients. t test, *: p < 0.05; ***: p < 0.001. The data are presented as the mean ± SD