Xiaoyaosan, a traditional Chinese medicine, inhibits the chronic restraint stress-induced liver metastasis of colon cancer .

Xiaoyaosan (XYS), a traditional Chinese medicine (TCM), has been widely used to relieve a variety of disorders caused by depression.
This study evaluates the effect of XYS against tumour metastasis in a chronic restraint stress mouse model.
Forty C57BL/6J mice were randomly divided into four groups, including blank-control (BC), blank-stress (BS), XYS-control (XC) and XYS-stress (XS). BS and XS groups were exposed to immobilization stress for 2 h per day for 28 days commencing seven days before tumour cell injection. XC and XS groups were given a gavage of XYS (1516.67 mg/kg) before chronic immobilization stress. Mice were injected with HT-29 colon cancer cells in the spleen to produce liver metastasis. After 28 days of injecting with HT-29 cells, flow cytometry, western blot, PCR and immunohistochemical staining were performed to uncover the role of chronic restraint stress and XYS in the liver metastasis of colon cancer.
Metastatic liver weight of mice in XS group (3.33 ± 0.18 g) was significantly lower than BS group (4.01 ± 0.27 g). Chronic restraint stress significantly increased CD11bF4/80 and CD11bGrLy6C cell infiltration. XYS treatment significantly decreased the CD11bF4/80 tumour-associated macrophage (TAM) population and CD11bGrLy6C myeloid-derived suppressor cell (MDSC). TGF-β, IL-6, MMP-9 and VEGF in spleen tumours significantly decreased in XYS group. XYS also reduced VEGF and CD31 in hepatic metastatic tissue, which were elevated by chronic restraint stress.
XYS may successfully inhibit chronic-stress-induced liver metastasis. Results suggest that XYS may have therapeutic value for colorectal cancer treatment.