title: The stem cell-associated antigen CD133 (Prominin-1) is a molecular therapeutic target for metastatic melanoma.
abstract: 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 downregulation 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. Downregulation of CD133, confirmed by immunocytochemistry, Western blotting, microarray analysis, and reverse transcription-polymerase chain reaction, 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 downregulation. Monoclonal antibodies directed against two different epitopes of the CD133 protein induced a specific, dose-dependent cytotoxic effect in FEMX-I cells. The downregulation 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 downregulated). Ten of the 76 upregulated 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 CSC marker, is an important therapeutic target for metastatic melanoma and, potentially, for other CD133-expressing cancer types.
authors.affiliation: Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama 36688, USA.
authors.forename: Germana
authors.initials: G
authors.lastname: Rappa
authors.forename: Oystein
authors.initials: O
authors.lastname: Fodstad
authors.forename: Aurelio
authors.initials: A
authors.lastname: Lorico
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D002465:Cell Movement; D002469:Cell Separation; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism*; D009362:Neoplasm Metastasis; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010455:Peptides; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018874:Spheroids, Cellular / Q000378:metabolism; D014407:Tumor Cells, Cultured; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; D051153:Wnt Proteins
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