Fig. 2: Gut microbiota modulates breast cancer progression exacerbated by chronic stress.

a Experimental design for the ABX treatment: mice were treated with sodium chloride or ABX for 7 days prior to dividing into two groups. One group was exposed to chronic restraint stress for 14 consecutive days before 4T1 cells inoculation and continued until the end of the experiment, while the other group was inoculated with 4T1 cells without stress exposure. The ABX groups received ABX throughout the experiment. Created with BioRender.com. b Tumor growth volume in the ABX treatment experiment (tumor group: n = 8, tumor + stress group: n = 5, tumor + ABX group: n = 8, tumor + stress + ABX group: n = 7). c Tumor weight and tumor burdens on the lung in the ABX treatment experiment (tumor group: n = 8, tumor + stress group: n = 5, tumor + ABX group: n = 8, tumor + stress + ABX group: n = 7). d Tumor-infiltrating CD8⁺ T cells and abundance of IFN-γ in tumor-infiltrating CD8⁺ T cells in the ABX treatment experiment (n = 5 per group). e Experimental design for the co-housing experiment, in which mice with non-stressed, stressed, and co-housed stressed conditions were inoculated with 4T1 cells, respectively. Created with BioRender.com. f Tumor growth volume in the co-housing experiment (n = 7 per group). g Tumor weight and tumor burdens on the lung in the co-housing experiment (n = 7 per group). h Tumor-infiltrating CD8⁺ T cells and IFN-γ abundance of tumor-infiltrating CD8⁺ T cells in the co-housing experiment (n = 5 per group). Data were presented as mean ± SEM. Statistical significance was determined using two-way ANOVA followed by Sidak’s multiple comparison test for (b–f) and one-way ANOVA followed by Tukey’s multiple comparisons test for (g, h). Significance levels are denoted as *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; “ns” indicates no significant difference. Source data and exact p values are provided in the Source data file.