Intestinal Microflora Are Necessary for Development of Spontaneous Adenocarcinoma of the Large Intestine in T-Cell Receptor b Chain and p53 Double-Knockout Mice

This study was conducted to confirm the hypothesis that intestinal microflora are required for the development of adenocarcinoma in the colon of the TCRb and p53 double-knockout (TCRb p53) mouse. Germ-free TCRb p53 mice were produced. At 7 weeks of age, the animals were divided into two groups (n 5 10/group), and one of these groups was conventionalized. Animals of both groups were subjected to histopathological examination for adenocarcinoma of the colon at 4 months of age. There was no development of adenocarcinoma of the colon among the germ-free mice, whereas in the conventionalized group, adenocarcinomas of the ileocecum and cecum were detected in 70% of animals. These results indicate the usefulness of the TCRb p53 mouse as a colon cancer animal model that develops spontaneous adenocarcinoma of the colon early in life, and suggest that intestinal microflora play a major role in the development of adenocarcinoma of the colon in this animal model.