A Flexible Reporter System for Direct Observation and Isolation of Cancer Stem Cells

Abstract

Summary: Many tumors are hierarchically organized with a minority cell population that has stem-like properties and enhanced ability to initiate tumorigenesis and drive therapeutic relapse. These cancer stem cells (CSCs) are typically identified by complex combinations of cell-surface markers that differ among tumor types. Here, we developed a flexible lentiviral-based reporter system that allows direct visualization of CSCs based on functional properties. The reporter responds to the core stem cell transcription factors OCT4 and SOX2, with further selectivity and kinetic resolution coming from use of a proteasome-targeting degron. Cancer cells marked by this reporter have the expected properties of self-renewal, generation of heterogeneous offspring, high tumor- and metastasis-initiating activity, and resistance to chemotherapeutics. With this approach, the spatial distribution of CSCs can be assessed in settings that retain microenvironmental and structural cues, and CSC plasticity and response to therapeutics can be monitored in real time. : In this article, Wakefield and colleagues show that a subpopulation of cancer cells with characteristics of cancer stem cells can be identified and visualized in vitro and in vivo using a lentiviral-based fluorescent reporter that responds to the presence of the stemness master transcription factors SOX2 and OCT4.