Module 12: Figure colon cancer

Progressive development of a typical colon cancer.

The normal development and differentiation of the intestinal cell is shown on the left. Approximately four stem cells located in the crypt proliferate relatively slowly to create the progenitor cells that then divide rapidly to produce the large population of cells that differentiate into intestinal cells as they migrate up the villus. The proliferation and maintenance of the crypt cells is regulated by Wnt, which probably comes from the mesenchymal cells. As the proliferating progenitor cells move up the crypt they come into contact with transforming growth factor β (TGF-β), which switches off proliferation and promotes intestinal cell differentiation. The oncogenic events that occur during the development of colon cancer are shown on the right, together with some of the prominent mutations that activate oncogenes and inactivate the tumour suppressors. Initially, a benign adenoma develops, which can then transform into a carcinoma with the potential for metastasis. (Adapted from information taken from Giles et al. 2003 and Mishra et al. 2005.)