Cancer stem cells: targets and potential biomarkers for radiotherapy
Cet article fait le point sur les études récentes concernant les biomarqueurs potentiels des cellules souches cancéreuses visant à développer des thérapies ciblées augmentant l'efficacité d'une radiothérapie
Cancer stem cells (CSC) have the unique ability to cause tumour recurrences if they survive treatment. By its curative potential, radiotherapy has functionally proven to sufficiently inactivate CSC. It is well known that CSC mediate radiation resistance of tumours by tumour-specific factors like pre-treatment CSC number or repopulation and reoxygenation during fractionated radiotherapy. The intrinsic radioresistance of CSC appears to be higher compared to non-CSC, a factor that is especially important for the development of predictive biomarkers that, if this finding holds true, could be successfully established only if they are stem-cell specific. Recent clinical data imply that stem-cell-related surface markers may be directly used as predictors for radiocurability of tumours with comparable risk factors like histology and size. Future studies need to address the question which additional markers need to be considered if more heterogeneous patient collectives are investigated. On the way to a direct targeting-approach, several drugs are currently being evaluated aiming to target CSC via inhibition of stem-cell related signal transduction pathways. Such drugs need to be preclinically tested as combined modality therapies in combination with radiotherapy to evaluate their curative potential, and need to be optimized by increasing the specificity to CSC over normal tissue stem cells to avoid increased radiation toxicity.