NAMPT Over-Expression Recapitulates the BRAF Inhibitor Resistant Phenotype Plasticity in Melanoma
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cancers-12-03855-v3.pdf
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6.4 MB
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Author(s)
Audrito, Valentina
Messana, Vincenzo Gianluca
Moiso, Enrico
Vitale, Nicoletta
Arruga, Francesca
Brandimarte, Lorenzo
Gaudino, Federica
Pellegrino, Elisa
Vaisitti, Tiziana
Riganti, Chiara
Date Issued
December 20, 2020
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Cancers 12 (12): 3855 (2020)
Version
Final published version
Abstract
Serine–threonine protein kinase B-RAF (BRAF)-mutated metastatic melanoma (MM) is a highly aggressive type of skin cancer. Treatment of MM patients using BRAF/MEK inhibitors (BRAFi/MEKi) eventually leads to drug resistance, limiting any clinical benefit. Herein, we demonstrated that the nicotinamide adenine dinucleotide (NAD)-biosynthetic enzyme nicotinamide phosphoribosyltransferase (NAMPT) is a driving factor in BRAFi resistance development. Using stable and inducible NAMPT over-expression systems, we showed that forced NAMPT expression in MM BRAF-mutated cell lines led to increased energy production, MAPK activation, colony-formation capacity, and enhance tumorigenicity in vivo. Moreover, NAMPT over-expressing cells switched toward an invasive/mesenchymal phenotype, up-regulating expression of ZEB1 and TWIST, two transcription factors driving the epithelial to mesenchymal transition (EMT) process. Consistently, within the NAMPT-overexpressing cell line variants, we observed an increased percentage of a rare, drug-effluxing stem cell-like side population (SP) of cells, paralleled by up-regulation of ABCC1/MRP1 expression and CD133-positive cells. The direct correlation between NAMPT expression and gene set enrichments involving metastasis, invasiveness and mesenchymal/stemness properties were verified also in melanoma patients by analyzing The Cancer Genome Atlas (TCGA) datasets. On the other hand, CRISPR/Cas9 full knock-out NAMPT BRAFi-resistant MM cells are not viable, while inducible partial silencing drastically reduces tumor growth and aggressiveness. Overall, this work revealed that NAMPT over-expression is both necessary and sufficient to recapitulate the BRAFi-resistant phenotype plasticity.
MIT Department
Koch Institute for Integrative Cancer Research at MIT
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DOI of Published Version
https://doi.org/10.3390/cancers12123855
