Abstract 2007: A novel CRISPR/Cas9 reporter system to monitor TNBC cancer stem cells in real time

Increasing evidence suggests that breast cancers arise from so-called cancer stem cells (CSC), which, consistent with their normal adult counterpart, are uniquely capable of long term self-renewal and differentiation into all bulk cancer cell types that exhibit unique epigenetic states within a tumor. While FACS has been instrumental to isolating these cells and quantifying efficacy of CSC targeted drugs in vitro and in vivo, having to remove cells from their native environment is an inherent limitation, thereby only providing a snapshot of information with each experiment. In order to directly visualize CSC dynamics in real time the CRISPR/Cas9 system was used to precisely knockin mCherry directly downstream of the final exon of ALDH1A3 in SUM149 triple-negative breast cancer cells. With regard to CSC properties, ALDH1A3 high cells were shown to be dramatically correlated with the ALDEFLUOR assay and functionally, increased ammosphere and tumor formation in vitro and in vivo. Strikingly, a single ALDH1A3 high cell was capable of reconstituting the entire heterogeneity of the parental cell line. With the ability to directly visualize CSCs we sought to utilize live cell imaging to observe population changes in response to varying therapeutics. As evident by mCherry fluorescence intensity we confirm previous findings that suggest conventional chemotherapeutics such as docetaxel enrich for CSCs while the natural product sulforpahane reduces the population. Taken together, we believe our mCherry reporter cells could be adapted to rapidly screen for novel inhibitors of CSCs in triple-negative breast cancers. Citation Format: Nathan A. Truchan, Johanna Buschhaus, Michael Brooks, Andre Halabu, Hongwei Guo, Hebao Yuan, Kathryn Luker, Max Wicha, Duxin Sun, Joseph P. Burnett. A novel CRISPR/Cas9 reporter system to monitor TNBC cancer stem cells in real time [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2007.