Abstract:Objective: TO investigate THE effect and mechanism of Houpu Sanwu Decoction on subcutaneous tumor in C57BL/6J mice. Methods: Mouse colorectal cancer MC-38 cells were subcutaneously injected into C57BL/6J mice to establish a subcutaneous tumor model of colorectal cancer. The mice with successful model were randomly divided into model control group, Houpu Sanwu decoction low-dose group, Houpu Sanwu decoction medium-dose group, Houpu Sanwu decoction high-dose group, 5-fluorouracil group (5-FU group), and combination group (5-fluorouracil + Houpu Sanwu decoction medium-dose group), with 6 mice in each group. The mice were treated with normal saline and Houpu Sanwu decoction by gavage or normal saline and 5-FU by intraperitoneal injection once a day for 24 consecutive days. During the intervention period, the mental state, diet and other general conditions of mice were regularly detected, and the changes in tumor volume of mice were regularly detected. After sampling, the subcutaneous tumors of each group were weighed and the pathological changes of subcutaneous tumors were observed by HE staining Transmission electron microscopy, Western blot and NTA were used to identify the exosomes derived from colorectal cancer tissues. RT-qPCR and WB were used to detect the mRNA and protein expression levels of Rab27a and exosome markers CD63, TSG101, and ALIX in tumor tissues.Results: Houpu Sanwu decoction could inhibit the growth of tumor in mice. The tumor growth was slow in all dose groups of Houpu Sanwu decoction and its combination group, and the tumor growth was inhibited to varying degrees. The anticancer effect of middle dose of traditional Chinese medicine was the best, and the combination group showed synergistic effect with 5-FU. Houpu Sanwu decoction could induce tumor necrosis, showing the same anticancer effect as 5-FU group, and the higher the dose, the more serious the necrosis was. Moreover, Houpu Sanwu decoction combined with 5-FU showed synergistic effect. Houpusanwu decoction can inhibit the protein and mRNA expression of Rab27a and exosome specific markers CD63, ALIX and TSG101 in mice.Conclusion: Houpu Sanwu Decoction inhibits the secretion of exosomes regulated by Rab27a possibly by inhibiting the secretion of exosomes.