Defining key molecular processes in cancer stem cells at single-cell level
Emma Jonasson1 Joakim Karlsson2, Salim Ghannoum1, Thomas Kroneis1,3, Erik Larsson2, Göran Landberg1, Anders Ståhlberg1
1Department of Pathology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; 2Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; 3Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
Cellular and genetic studies have revealed large variability within tumors and proven the existence of cancer stem cells (CSCs). Through asymmetric cell division, CSCs are maintained as low-proliferating cells, while the other cells generate expansion phase cells with high proliferation rates that will mature into more differentiated cell types. Our specific aims are to identify subpopulations of cancer cells, to define regulatory pathways that control CSC transitions and further define key steps in identified pathways and evaluate their potential as drug targets. The development of single-cell analysis has improved the possibilities of studying subpopulations of tumor cells. We have optimized a protocol for preparing RNA sequencing libraries from single-cells and have performed RNA sequencing on single-cells from two different cancer types, breast cancer and myxoid liposarcoma. Using staining methods and functional assays we collected and sorted cells from different stages regarding stemness, differentiation and proliferation. Using information about the cells received from sorting combined with their molecular expression signature, we could reconstruct and further define the differentiation process and identify processes involved in the transitions between different cell states. Furthermore, we were able to identify markers important for the CSC population, which we currently are validating using functional assays.
This work was supported by funding from the Swedish Cancer Society, Sahlgrenska Academy (ALF), the Swedish Childhood Cancer Foundation and Swedish Society for Medical Research.