Abstract

To construct a spontaneous colorectal cancer (CRC) mouse model with an Apc gene point mutation (ApcL850X) using CRISPR/Cas9 technology and preliminarily validate the composition and role of intestinal microbiota in colon cancer induced by Apc mutations. ApcL850X mice and wild-type (WT) controls were observed from 3 to 25 weeks of age. Comprehensive analyses were performed to evaluate body weight, food consumption, survival rates, routine blood parameters, and intestinal microbiota composition. Gut microbiota was assessed through high-throughput sequencing of 16S rRNA genes. Combined receiver operating characteristic (ROC) analysis was conducted to evaluate the diagnostic potential of gut microbiota composition for CRC. The Apc gene point mouse model (ApcL850X) was successfully generated, and the genetic stability of the strain was proved by the subsequent breeding process. Male ApcL850X mice showed significant differences in body weight and food intake compared to WT, while female ApcL850X mice did not. All male ApcL850X mice died by 23 weeks, with a 15% survival rate in females. Blood tests indicated inflammation and anemia in ApcL850X mice. Histopathology revealed intestinal polyps and tumors, mainly in the ileum, with no sex difference in tumor counts. Gut microbiota analysis showed significant differences between ApcL850X and WT mice, with reduced Lactobacillus and increased Alistipes and Bacteroides. ROC analysis showed area under the curve values of 0.72 for females and 0.67 for males. We established an Apc gene point mutation mouse model, resulting in a spontaneous CRC model. Phenotypic validation of ApcL850X mice indicated CRC development between 15 and 20 weeks of age, with gut microbiota changes starting after 15 weeks. Alterations in specific gut microbiota, such as reductions in lactobacilli, were associated with increased CRC risk. This model is valuable for studying the Apc gene's biological function and CRC treatments. Gut microbiota composition showed moderate potential as a non-invasive CRC diagnostic tool, with notable sex-specific differences. Further research is needed to validate these findings and improve diagnostic accuracy.

Key words: Colorectal cancer; familial adenomatous polyposis; Apc gene mutation; CRISPR/Cas9; gut microbiota