A method for tracking cancer cells that survive radiation treatment in mice is reported in a study published in Nature Communications this week. These findings permit the study of the surviving cells in mice and may aid in the treatment of the resistant cells.

Solid tumours are known to have areas in their centre that have a low oxygen supply - hypoxia - and this has been associated with the resistance to radiation treatment. Hiroshi Harada and colleagues tag cells based on the presence or absence of a transcription factor HIF1alpha that has been associated with hypoxic tissues. They identify cancer cells that are resistant to radiation treatment in mice and show that these surviving cells are initially negative for HIF1alpha but later acquire high levels of this protein. They also show that these cells move towards blood vessels in the surviving tumour.

Their findings reveal more information about the molecular features of the cells that are resistant to radiation and suggest that targeting cells that express HIF1alpha may be an appropriate strategy for treating radiation resistant cancer.