BioProject

CD133 (Prominin-1) is considered the most important cancer stem cell (CSC)-associated marker identified so far, with increased expression in the CSC fraction of a large variety of human malignancies, including melanoma. More...

CD133 (Prominin-1) is considered the most important cancer stem cell (CSC)-associated marker identified so far, with increased expression in the CSC fraction of a large variety of human malignancies, including melanoma. Here we investigated the effects of CD133 down-regulation in vitro and in vivo in human metastatic melanoma. The average number of CD133 molecules on the cell surface of FEMX-I melanoma cells was decreased by 8.7-fold and 1.8-fold using two different short hairpin RNAs. Down-regulation of CD133, confirmed by immunocytochemistry, Western blotting, microarray analysis and RT-PCR, resulted in slower cell growth, reduced cell motility, and decreased capacity to form spheroids under stem cell-like growth conditions. Clonal analysis revealed that the reduction in growth rate was proportional to the extent of CD133 down-regulation. Monoclonal antibodies directed against two different epitopes of the CD133 protein induced a specific, dose-dependent cytotoxic effect in FEMX-I cells. The down-regulation of CD133 severely reduced the capacity of the cells to metastasize, particularly to the spinal cord. In the CD133 downregulated cells, microarray analysis revealed expression changes for only 143 annotated genes (76 up- and 67 down-regulated). Ten of the 76 up-regulated genes coded for Wnt inhibitors, suggesting an interaction between CD133 and the canonical Wnt pathway. We conclude that CD133, in addition to its role as a cancer stem cell marker, is an important therapeutic target for metastatic melanoma and, potentially, for other CD133-expressing cancer types. Overall design: Two control experiments and two CD133 knockdown experiments. Less...