Abstract 2656: Using Nanog expression to identify breast cancer stem cell populations.

Abstract

Abstract Many tumors have been demonstrated to contain a subpopulation of cancer stem cells (CSC) whose epigenetic modifications convey resistance to conventional therapies. Furthermore, tumor expression of genes associated with pluripotent embryonic cells, such as Oct-4, Sox-2 and Nanog, often correlates with poor prognosis. We hypothesized that expression of transcription factors that are required for induction and maintenance of pluripotency (Oct-4, Sox-2 and Nanog) 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% of the cells. These GFP+ cell could be easily isolated by FACS cell sorting. On subsequent in vitro cell culture of GFP+ populations, up to 80% of the cells became GFP- over a period of 4 weeks. This would be consistent with a subsequent differentiation of these cells. By contrast GFP- populations remained 100% GFP-. In vitro CSC surrogate assays show that Nanog-GFP+ cells produced more spheroids in soft agar and under non-adherent growth conditions. More importantly, in vivo cell transfer studies demonstrated that Nanog-GFP+ cells were more efficient at generating experimental lung metastases when compared to Nanog-GFP-cells. Interestingly Nanog-GFP+ cells were more resistant to the chemotherapeutic drugs paclitaxel and bortezomib. However targeting the extrinsic apoptosis pathway with a combination of bortezomib and agonist antibodies to the TRAIL death receptor DR5 was equally effective against both Nanog-GFP+ and Nanog-GFP- cells. These findings suggest that Nanog promoter activity is a robust marker of highly metastatic 4T1.2 CSC subpopulations, and suggests that eradication of such cells may be required for improved anti-cancer therapies. Funded by NCI Contract HHSN261200800001E Citation Format: Alan D. Brooks, Rachel L. de Kluyver, Jimmy K. Stauffer, Marcella Kaddoura, Thomas J. Sayers. Using Nanog expression to identify breast cancer stem cell populations. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2656. doi:10.1158/1538-7445.AM2013-2656