Dnmt1N/+ Reduces the Net Growth Rate and Multiplicity of Intestinal Adenomas in C57BL/6-multiple Intestinal Neoplasia (Min)/+ Mice Independently of P53 but Demonstrates Strong Synergy with the Modifier of Min 1(AKR) Resistance Allele

Altered patterns of the 5-cytosine methylation of genomic DNA are associated with the development of a wide range of human cancers. We have studied the mechanisms and genetic pathways by which a targeted heterozygous deficiency in the murine 5-cytosine DNA methyltransferase gene (Dnmt1(N/+)) diminishes intestinal tumorigenesis in C57BL/6-multiple intestinal neoplasia (Min)/+ mice. We found that Dnmt1(N/+) retards the net growth rate of intestinal adenomas and reduces tumor multiplicity by approximately 50%. This tumor resistance affects the entire intestinal tract and is independent of the status of modifier of Min 1 and p53, two loci that have been found to confer strong resistance to Min-induced neoplasia Interestingly, Dnmt/(N/+) and modifier of Min 1 resistance interact synergistically, together virtually eliminating tumor incidence. This finding may provide an insight into potential combinatorial therapeutic approaches for treating human colon cancer.