The Min mouse, which has a germ line mutation in 1 allele of the Apc tumor
suppressor gene, is a model for the early steps in human colorectal cancer.
Helicobacter pylori infection, a known risk factor for gastric cancer in h
umans, causes chronic inflammation and increased epithelial cell proliferat
ion in the stomach. Infection with the bacterium Citrobacter rodentium is k
nown to increase epithelial cell proliferation and to promote chemically in
itiated tumors in the colon of mice. Min mice infected with C. rodentium at
1 month of age were found to have a 4-fold increase in the number of colon
ic adenomas at 6 months of age, compared with uninfected Min mice. Most of
the colonic adenomas in the infected Min mice were in the distal colon, whe
re C. rodentium-induced hyperplasia occurs. These data demonstrate that bac
terial infection promotes colon tumor formation in genetically susceptible
mice.