In this study, we established a novel epirubicin (EPB)-induced multi-drug-resistant CSC-like breast cancer cell line (4T1/EPB) and tested the hypothesis that STING agonist might enhance the anti-tumor efficacy of α-Al2O3-UPs-4T1/EPB (UPs-4T1/EPB for short) nanovaccine. This evidence concerns the gene STING1 and breast cancer.