title: Wnt interaction and extracellular release of prominin-1/CD133 in human malignant melanoma cells.
abstract: Prominin-1 (CD133) is the first identified gene of a novel class of pentaspan membrane glycoproteins. It is expressed by various epithelial and non-epithelial cells, and notably by stem and cancer stem cells. In non-cancerous cells such as neuro-epithelial and hematopoietic stem cells, prominin-1 is selectively concentrated in plasma membrane protrusions, and released into the extracellular milieu in association with small vesicles. Previously, we demonstrated that prominin-1 contributes to melanoma cells pro-metastatic properties and suggested that it may constitute a molecular target to prevent prominin-1-expressing melanomas from colonizing and growing in lymph nodes and distant organs. Here, we report that three distinct pools of prominin-1 co-exist in cultures of human FEMX-I metastatic melanoma. Morphologically, in addition to the plasma membrane localization, prominin-1 is found within the intracellular compartments, (e.g., Golgi apparatus) and in association with extracellular membrane vesicles. The latter prominin-1-positive structures appeared in three sizes (small, ≤40 nm; intermediates ~40-80 nm, and large, >80 nm). Functionally, the down-regulation of prominin-1 in FEMX-I cells resulted in a significant reduction of number of lipid droplets as observed by coherent anti-Stokes Raman scattering image analysis and Oil red O staining, and surprisingly in a decrease in the nuclear localization of beta-catenin, a surrogate marker of Wnt activation. Moreover, the T-cell factor/lymphoid enhancer factor (TCF/LEF) promoter activity was 2 to 4 times higher in parental than in prominin-1-knockdown cells. Collectively, our results point to Wnt signaling and/or release of prominin-1-containing membrane vesicles as mediators of the pro-metastatic activity of prominin-1 in FEMX-I melanoma.
authors: Cancer Research Program, Roseman University of Health Sciences, 10530 Discovery Drive. Las Vegas, NV 89135, USA.
authors: Germana
authors: G
authors: Rappa
authors: Javier
authors: J
authors: Mercapide
authors: Fabio
authors: F
authors: Anzanello
authors: Thuc T
authors: TT
authors: Le
authors: Mary G
authors: MG
authors: Johlfs
authors: Ronald R
authors: RR
authors: Fiscus
authors: Michaela
authors: M
authors: Wilsch-Bräuninger
authors: Denis
authors: D
authors: Corbeil
authors: Aurelio
authors: A
authors: Lorico
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D001391:Azo Compounds / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008055:Lipids / Q000032:analysis; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D009361:Neoplasm Invasiveness / Q000473:pathology; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D025941:Protein Interaction Mapping; D013059:Spectrum Analysis, Raman; D051820:TCF Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D001391:Azo Compounds; D014408:Biomarkers, Tumor; C495270:CTNNB1 protein, human; D006023:Glycoproteins; D008055:Lipids; C000606023:PROM1 protein, human; D010455:Peptides; D051820:TCF Transcription Factors; D051176:beta Catenin; C011049:oil red O