In some adenomas of the colon, intestinal crypt cells appear to have proliferate

Question

In some adenomas of the colon, intestinal crypt cells appear to have proliferated abnormally to form small tumors known as polyps. Studies on the familial type of such a disease led to the identification of a major signaling pathway (which was aberrant in the polyp cells) as being involved in the maintenance of the gut stem-cell compartment. What signaling pathway is this? Is it upregulated or downregulated in colon cancers?

A.MAPK pathway; up-regulated

B.MAPK pathway; down-regulated

C.Wnt pathway; up-regulated

D.Wnt pathway; down-regulated

E.Hedgehog pathway; down-regulated

Explanation / Answer

Various in-vivo studies have found that the Wnt pathway is necessary for the proper maintenance of the structure of the epithelium of the intestine. The permanent activation of this pathway is also responsible for the proper proliferation of its precursor cells. Due to mutation of adenomatous polyploid coli (APC) tumor suppresor gene, which in turn inhibits APC binding, the downregulation and consequent inactivation of which results in the formation of polyps.

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