Increased expression of CD133 and reduced dystroglycan expression are strong predictors of poor outcome in colon cancer patients.

Background Expression levels of CD133, a cancer stem cell marker, and of the alpha-subunit of the dystroglycan (alpha-DG) complex, have been previously reported to be altered in colorectal cancers. Methods Expression levels of CD133 and alpha-DG were assessed by immunohistochemistry in a series of colon cancers and their prognostic significance was evaluated. Results Scattered cells positive for CD133 were rarely detected at the bases of the crypts in normal colonic mucosa while in cancer cells the median percentage of positive cells was 5% (range 0--80). A significant correlation was observed with pT parameter and tumor stage but not with tumor grade and N status. Recurrence and death from disease were significantly more frequent in CD133-high expressing tumors and Kaplan-Meier curves showed a significant separation between high vs low expressor groups for both disease-free (p = 0.002) and overall (p = 0.008) survival. Expression of alpha-DG was reduced in a significant fraction of tumors but low alpha-DG staining did not correlated with any of the classical clinical-pathological parameters. Recurrence and death from the disease were significantly more frequent in alpha-DG-low expressing tumors and Kaplan-Meier curves showed a significant separation between for both disease-free (p = 0.02) and overall (p = 0.02) survival. Increased expression of CD133, but not loss of alpha-DG, confirmed to be an independent prognostic parameters at a multivariate analysis associated with an increased risk of recurrence (RR = 2.4; p = 0.002) and death (RR = 2.3; p = 0.003). Conclusions Loss of alpha-DG and increased CD133 expression are frequent events in human colon cancer and evaluation of CD133 expression could help to identify high-risk colon cancer patients.