Accordingly, mutation signature analysis in Lynch colorectal cancers revealed that KRAS and APC mutations commonly occur after the onset of MMR deficiency.
Stemming from a mutation in the adenomatous polyposis coli (APC) gene, Gardner syndrome shares genetic correlations with the FAP phenotype; as a result, it becomes all the more crucial for physicians to be able to discern Gardner syndrome from other differential diagnoses such as Turcot syndrome, FAP, and other attenuated forms of familial polyposis.
To further explore intestinal regional responses, we studied effects of sulindac on additional gene-targeted mouse models of human intestinal tumorigenesis; these were (i) Apc(1638N/+) mouse (chain termination mutation in exon 15 of the Apc gene); (ii) Mlh1(+/-) mouse (DNA mismatch repair deficiency, a mouse model of human hereditary non-polyposis colorectal cancer) and (iii) double-heterozygous Mlh1(+/-)Apc(1638N/+) mutant mouse.
Germline mutations of APC in patients with Turcot syndrome (colon cancer and medulloblastoma), was well as somatic mutations of APC, beta-catenin, and Axin in sporadic medulloblastomas (MBs) have shown the importance of WNT signaling in the pathogenesis of MB.
A subset of cases is associated with colon cancer and APC germline mutations (Turcot syndrome), and APC and beta-catenin point mutations occur in up to 10% of sporadic cases, indicating the involvement of the Wnt pathway in the development of medulloblastoma.
The adenomatous polyposis coli (APC) gene, a member of the Wingless/Wnt signal transduction pathway, has been implicated in the development of medulloblastomas in Turcot's syndrome. beta-catenin also functions in this highly conserved signaling pathway and is instrumental in growth and development.
These results suggest that the APC gene is associated with pathogenesis of one feature of TS, but that at least one other gene is responsible for the genesis of neuroepithelial tumors in the CNS.