To study the inhibitory effect of Fuzheng Xiao'ai Formula I on colorectal cancer tumors in nude mice from the perspective of intestinal flora.

The CRC nude mouse model was constructed and 20 successfully modeled nude mice were randomLy divided into the model control group and low dose (17.47 g/kg), medium dose (34.94 g/kg), and high dose (69.89 g/kg) groups of Fuzheng Xiao'ai Formula I, with 5 mice in each group. The model control group was gavaged with normal saline, and each dose of Fuzheng Xiao'ai Formula I was gavaged with the corresponding concentration of decoction. After 2 consecutive weeks of intervention, the nude mice were sacrificed, the tumor bodies were completely dissected, and some tumor tissues were taken for HE staining. Based on the tumor weight, volume and pathological results, the medium dose group with better efficacy was screened out. Meanwhile, the cecal contents of this group and the model control group were collected for metagenomic sequencing analysis.

The tumor weight and volume of nude mice in each dose group of Fuzheng Xiao'ai Formula I decreased. HE staining showed that the density of tumor cells in the low, medium, and high dose groups of Fuzheng Xiao'ai Formula I decreased, accompanied by different degrees of necrosis. Metagenomic sequencing showed that compared with the model control group, the abundances of Parabacteroides, Bifidobacterium, Faecalibacterium, Clostridium auriscati, and Faecalibaculum rodentium in the medium dose group significantly increased (P < 0.05), and the abundances of Proteus, Citrobacter, Morganella, Enterobacter, Morganella morganii, and Enterobacter hormaechei significantly decreased (P < 0.05). Kyoto Encyclopedia of Genes and Genomes analysis found that the starch and sucrose metabolism pathway was significantly different between the two groups (P < 0.05), among which α-glucosidase, UTP-glucose-1-phosphate uridylyltransferase, phosphoglucomutase, and maltose α-D-glucosyltransferase were significantly downregulated in this pathway (P <0. 05).

Fuzheng Xiao'ai Formula I repairs the intestinal barrier and maintains the homeostasis of the intestinal environment by increasing the abundance of beneficial bacteria and reducing the abundance of harmful bacteria. Down-regulating α-glucosidase in the starch and sucrose metabolism pathway may be a potential way for it to exert anti-colorectal cancer effects.