How asbestos triggers cancer

Everyone knows asbestos causes cancer, but now researchers can explain how. A tricky paradox long plagued asbestos cancer studies: Cells in a dish exposed to asbestos always died, but cells in the body survived and became malignant. It turns out our immune system is mostly to blame (Proc. Natl. Acad. Sci. USA, published online, dx.doi.org/10.1073/pnas.0604008103). "Rather than fighting cancer, the immune system often helps cancer to grow, in this case by helping the cell survive the genetic insult from asbestos," says Michele Carbone of the University of Hawaii. When macrophages devour asbestos, they release a distress-call protein called TNF-α. This alerts the NF-??B protein on nearby cells, which activates the cellular machinery that prevents cell death. Cells are protected from asbestos in the short term but become malignant in the long term. Without a mechanism, researchers have struggled to develop drugs for asbestos-linked cancer. "This work has provided at least two targets," comments Matthew B. Grisham of Louisiana State University Health Sciences Center. "The next step is to inhibit those targets in an animal model."