To help itself grow, a tumor forms its own network of blood vessels for nutrient delivery. A number of cancer-fighting drugs aim to block this growth, called angiogenesis. Now, a team of researchers led by Paul S. Frenette and Claire Magnon of Albert Einstein College of Medicine, in New York City, has discovered that prostate cancer tumors grow, and even migrate in the body, with help from certain types of nerve fibers (Science 2013, DOI: 10.1126/science.1236361). As is the case for angiogenesis, the researchers expect that drugs might one day halt tumor proliferation by targeting these fibers. To pinpoint the nerves involved, the scientists monitored prostate tumor growth in mice while disabling various sets of nerves and protein receptors in the animals. One type of nerve fiber the team identified infiltrates a tumor’s edges, releasing norepinephrine to activate adrenergic receptors on the cells there. A second type of nerve fiber localizes inside the tumor and releases acetylcholine to activate a receptor, dubbed Chrm1, on surrounding cells. These interactions cause the tumor to grow and spread throughout the body, respectively. The team isn’t sure why prostate tumors need nerve fibers to thrive, Frenette says, but it plans to investigate further.