Friendly neighbours feed tumour cells

In pancreatic cancer, neighbouring non-cancerous cells degrade their own proteins through a process called autophagy and release amino acids that are then taken up and used by the cancer cells. See Letter p.479 Cancer cells generally have metabolic needs that differ from those of neighbouring normal cells, and hence display rewired metabolic networks. Cristovao Sousa et al. show that, in pancreatic cancers, stellate cells in the tumour environment supply cancer cells with the amino acid alanine as the carbon needed for anabolic processes when other sources are scarce. Tumour cells in turn stimulate autophagy in stellate cells, which is needed for alanine secretion. This cross-talk allows pancreatic cancer cells to fulfil their metabolic requirements in an environment lacking in other essential nutrients.