Materials science - Film review

Stem cells that initiate and maintain cancers are so like normal stem cells that it's hard to design drugs to target them specifically. This is a serious problem as, for example, damaging blood stem cells in leukaemia therapy can cause haematopoietic failure and death. Now a study of the tumour suppressor PTEN, often inactivated in leukaemia and other cancers, pinpoints a major difference between self-renewal in normal and cancer stem cells. PTEN normally inhibits the phosphatidylinositol-3-OH kinase signalling pathway, limiting cell proliferation and survival. In the absence of PTEN, leukaemic stem cells proliferate, but normal stem cells are depleted. This suggests that PTEN-mimicking drugs may act against leukaemia yet preserve blood stem cells. Indeed, in Pten-deficient mice rapamycin kills leukaemic stem cells but rescues normal stem cell function. A separate study confirms PTEN's role in blood stem cell regulation.