Cancer stem cells (CSCs) are presently defined based on the presence of certain cell suface or intracellular markers as one of the criteria. For breast cancer stem cells, this comprises, for example, the CD44+/CD24low status, CXCR1, or ALDH1, which are commonly determined by flow cytometry. There are other markers, which may prove useful for CSC identification, however, including, for example, OCT4 and potentially a number of proteins associated with EMT (see also project in Unit 5). Flow cytometry offers the principal advantage to determine the marker status for each individual cell within a population, but requires substantially huge amounts of cells and thus is time- and resource-intense.
The goal of this project is to develop the tools and conditions for detecting CSC-markers in protein preparations of cells, which are arrayed on a chip format. The challenge associated with this is to find the appropriate balance between the accurate quantification of the CSC-markers in minute amounts of protein (corresponding the protein content of a single cell or less) and to achieve a sufficiently high throughput, so that the method can be used for future diagnostic approaches as well as for systematic large scale screens (see also: Unit 5).