Notch1 enhances NF-κB activation to promote CD133+ Skin Cancer Stem Cells. Homo sapiens

Cancer stem-like cells are hypothesized to be the major tumor initiating cell (TIC) population of human cutaneous squamous cell carcinoma (hcSCC), but the molecular alterations underpinning their cellular phenotype remain undefined. Here, a small CD133+CD31-CD45-CD61-CD24- (CD133+) cell population enriched for self-renewing and TIC features was isolated by sorting from primary hcSCC tumors. CD133+ cells show enhanced spheroid formation in vitro and tumor generation in vivo. Gene expression profiling comparing CD133+ with CD133- cells revealed that CD133+ cells expressed enriched stem cell-like and cancer-related gene signatures. Eighty differentially expressed stem cell-related genes were identified in CD133+ cells, where the top pathways include Notch, Notch1-mediated NF-κB, and WNT signaling. Overexpression of growth factor receptors, PI3K/mTOR, and STAT pathway genes and inactivation of genes regulating epigenetic modification of chromatin implicated in cancer were also identified. Verification of these gene signatures was conducted with Nanostring in an independent tumor set. Pharmacologic or genetic modulation of Notch1, IKKα, RELA and RELB modulated NF-κB transactivation, the CD133+ population, and phenotype. Immunofluorescent staining confirmed co-localization of CD133+ and IKKα expression in SCC tumor specimens. Our data support the linkage and importance of non-canonical Notch1 and IKK-mediated NF-κB activation in promoting CD133+ population and TIC phenotype in hcSCC. Overall design: Comparing Gene expression profiling for CD133+ with CD133- cells from the sorting from primary hcSCC tumors by 15 samples for both positive and neg in total 30 samples.