Xuanhusuo powder has an anti-breast cancer effect by inhibiting myeloid-derived suppressor cell differentiation in the spleen of mice through down-regulating granulocyte colony stimulating factor.

Objectives: To investigate the mechanism of Xuanhusuo powder (XHSP) inhibiting the differentiation of spleen myeloid-derived suppressor cells (MDSCs) in breast cancer mice.

Methods: Forty-eight BALB/c female mice aged 4-5 weeks were selected, 6 of them were in normal control group, while others were in tumor-bearing models established by orthotopic injection of 4T1 cells into the subcutaneous fat pad of the second pair of left mammary glands. The tumor-bearing mice were divided into granulocyte colony stimulating factor (G-CSF) control group, G-CSF knock-down group, model control group, XHSP small dose group, XHSP medium dose group, XHSP high dose group, and cyclophosphamide (CTX) group, with 6 mice in each group.