Cancer stem cells are not more radioresistant than non-stem cells in cell lines from different origins with the exception of the MDA MB231 breast cancer cell line
Osama Al-Assar, Ruth Muschel, Thomas Brunner
Radiation Oncology and Biology, University of Oxford, Oxford, UK
Background
A growing body of evidence is supporting the stem cell origin of human malignancy. The aim of this work is to identify and exploit (radio)biological differences of cancer ‘stem’ cells (CSC) compared to non-CSC in cell lines of different solid tumour entities
Method
CSC were isolated using CSC-specific cell surface markers. Sorting of the CSC was done using either magnetic beads or FACS.
Results
Our findings show that only CD24- ESA+ sorted MDA MB231 cells have enhanced radioresistance compared to the unsorted cells, which was reversed three weeks after sorting. In addition, the CD24- ESA+ sorted MDA MB231 cells show enhanced tumourigenecity in anchorage independent growth assay. We also demonstrate that CD24+ ESA+ sorted PANC-1 and PSN-1 cells although have no clonogenic survival advantage, show 40% and 61% reduction in γ-H2AX foci formation compared to the unsorted population , respectively.
Conclusion
These results demonstrate that cancer stem cells from the cell lines studied have no survival advantage in clonogenic survival after ionising radiation. This merits further investigation into identifying biologically relevant differences between CSC and non-CSC that are critical for tumour control and relapse prevention.
