Blocking protein recycling to kill tumor cells

All cells can recycle unwanted proteins and reuse the building blocks as food. Cancer cells ramp up this system, called autophagy, and rely on it to escape damage from chemotherapy and other treatments. Now, researchers at the University of Pennsylvania, have developed a drug to stop this. They showed previously that a malaria drug, hydroxychloroquine, reduces autophagy in cancer cells. But, it's not always possible to give patients a high enough dose of hydroxychloroquine to have an effect on tumor cells. The researcehers teamed up with chemists to design a more potent version of chloroquine. Unlike hydroxychloroquine, which has little impact on tumor cells when used as a single agent, the new drug, called Lys05, slows tumor growth in animal models even in the absence of other therapies. The Lys05 dose that is toxic to cancer cells, which are addicted to recycling and rely on it much more heavily than healthy cells, has little or no effect on healthy cells.