NEW YORK, N.Y., June 20 -- Is the body made of minature samurais? In the July/August issue of The Sciences magazine Martin C. Raff, a biologist from University College, London, reports on his research, saying that virtually all cells are programmed to commit hari-kiri if their neighbors do not offer them continual support. If he's right, the findings could be good news for work on treating cancer, heart disease, Alzheimer's and Parkinson's disease.
With the exception of early fetal cells, all cells appear to have poisonous proteins stashed beneath their membranes. Like spies with cyanide pills under the skin, cells pack these suicidal enzymes away for extreme emergencies, releasing them only when neighboring cells drop out of communication. "Cellular neighborhoods seem to be more conformist than any middle-class suburb," Raff writes. "As long as the cells reproduce and behave according to local norms, they are allowed to go on living." One foot out of step, and the cell is history.
The interesting thing about Raff's research is that it suggests that suicide is the cell's default setting. The death machinery is always in place, ready to be activated. There are many evolutionary advantages to this set-up, Raff says in The Sciences. "Such a mechanism could ensure that any cell that ends up in the wrong place is automatically eliminated: isolated from its life-affirming partners, it quickly dispatches itself." A cell's suicidal tendencies may be an organism's key weapon in the fight against cancer and autoimmune diseases: cells that wander too far from their source of molecular signals naturally self-destruct. When the self-destruction mechanism is disrupted, though, cancerous tumors made up of rapidly reproducing cells can result.