Abstract 3019: Aberrant NF-κB and Notch pathways promote CD133+ cancer stem cells in human primary cutaneous squamous cell carcinoma

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA The cancer stem cell (CSC) subpopulation has been implicated in inducing tumorigenesis and drug resistance, however, the unique gene program and regulatory signaling that contribute to the CSC phenotypes in human cutaneous squamous cell carcinoma (hcSCC) have not been defined. In this study, a newly improved cell sorting method was developed using a panel of multiple cell surface markers to isolate the small percentage of CD133+ cell population enriched for CSC in primary hcSCC specimens. These cells exhibited CSC features including enhanced spheroid formation in vitro and tumor formation in vivo. Distinct gene expression signatures of the CD133+ subset were profiled by comparing CD133+ CSC with CD133- cancer cells using microarray, which revealed that CD133+ cells expressed enriched stem cell and cancer-related gene programs. In the CD133+ subset, 80 differentially expressed stem cell genes were identified, with an additional set of 69 altered genes enriched in key regulatory pathways, including Notch, NF-κB, Wnt, EMT, and STAT signaling, using Gene Ontology (GO) and Ingenuity Pathway Analysis (IPA). The expression patterns of combined signature genes of CSC and the key regulatory pathways were validated with Nanostring gene expression assay in independent tumor samples. Notch and NF-κB signaling emerged as important pathways. Inhibitors or siRNA knockdown of Notch1/2 and IKKα inhibited NF-κB activity and altered CSC phenotypes, including percentage of CD133+ cells, colony and spheroid formation. Elevated NF-κB signaling was observed in CSCs in the tumor tissues, where immunofluorescent staining showed co-localization of CD133+ and molecules of NF-κB pathway in SCC tumor specimens. Our data support the importance of aberrant NF-κB and Notch signaling in promoting CSC gene program and biologic functions, which could represent predictive diagnostic and prognostic parameters and potential targets for skin cancer prevention and treatment. Supported by NIDCD intramural projects ZIA-DC-000016, 73 and 74. Citation Format: Xinxin Quan, Nga Voong, Weiping Chen, Jamie Coupar, Steven Lee, David W. Petersen, Daniel C. Edelman, Paul S. Meltzer, Andrew Montemarano, Martin Braun, Jonathan Vogel, Carter Van Waes, Zhong Chen. Aberrant NF-κB and Notch pathways promote CD133+ cancer stem cells in human primary cutaneous squamous cell carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3019. doi:10.1158/1538-7445.AM2014-3019