Figure 4.

CRC specific markers released by tumor cells exfoliated in the stools: ITGA6. In the normal intestine, cell exfoliation is a regular process by which the oldest epithelial cells become apoptotic and are replaced by new ones produced in the lower crypt. Cell components such as nucleic acids are subject to rapid degradation resulting in a weak accumulation of intact host components in the stools. In contrast, primary tumors protruding into the lumen release a significant number of intact CRC cells that are resistant to apoptosis. Over-expressed cancer cell components such as ITGA6 are thus likely protected from degradation and can be recovered in detectable levels by standard extraction making them good biomarkers for CRC screening.