Abstract 3876: Can Nanog activity identify aggressive breast cancer stem cell populations

Many tumors have been demonstrated to contain cancer stem cells (CSC). We hypothesized that expression of transcription factors that are required for induction and maintenance of pluripotency would be a possible alternative to cell surface phenotype for identification of CSC populations. Therefore we evaluated Nanog expression in 4T1.2 murine breast carcinoma cells, as a biomarker for CSC sub-populations. Introduction of a Nanog promoter reporter that drives destabilized GFP into 4T1.2 cells resulted in a stable expression of GFP in about 1-3% of the cells. On in vitro cell culture of FACS sorted GFP+ populations, up to 80% of the cells became GFP- over a period of 4 weeks, whereas GFP- populations remained 100% GFP-. In vitro CSC surrogate assays show that Nanog-GFP+ cells exhibited CSC characteristics, with enhanced colony formation in methylcellulose and increased survival in serum-free media. Nanog-GFP+ cells were also more efficient at generating experimental lung metastases following intravenous injection. In addition Nanog-GFP+ cells were also more resistant to the chemotherapeutic drugs paclitaxel and bortezomib. However targeting the extrinsic apoptosis pathway in vitro with a combination of bortezomib and agonist antibodies to the TRAIL death receptor DR5 was equally effective against both Nanog-GFP+ and Nanog-GFP- cell populations. To monitor Nanog expression in human breast cancer cells (SUM159), we used lentiviral vectors to introduce DNA constructs of the Nanog response element driving GFP and luciferase. About 0.5% of the SUM159 cells were GFP+ by FACS, and these cells also demonstrated some CSC characteristics such as enhanced colony formation in methylcellulose. Levels of GFP were increased in the SUM159 cells following cell culture under hypoxic conditions. These findings suggest that Nanog activity may be useful as surrogate marker of aggressive breast CSC subpopulations. Funded by NCI Contract HHSN261200800001E Citation Format: Thomas J. Sayers, Rachel de Kluyver, Marcella Kaddoura, Jim Stauffer, Poonam Tewary, Alan D. Brooks. Can Nanog activity identify aggressive breast cancer stem cell populations. [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 3876. doi:10.1158/1538-7445.AM2014-3876