A U.S. scientist and two British researchers have been awarded this year's Nobel Prize in medicine. They will share the prize for their studies of how genes regulate organ development and the death of cells.
The Nobel Assembly at Sweden's Karolinska Institute has recognized the work of Britons Sydney Brenner of the Salk Institute in California, and John Sulston of Cambridge University, and American Robert Horvitz of the Massachusetts Institute of Technology.
The committee cites them for using a lowly worm called c. elegans to identify the genetic basis by which cells in a fertilized egg differentiate into various organs and how nature programs cells to die as a normal part of that development.
A Rockefeller University scientist who has worked with Mr. Horvitz, Shai Shaham, says it was Mr. Brenner who established the worm as a novel experimental organism, preparing the way for the discoveries by the other two men. "Really, what has turned out to be the remarkable story here is that the program that was elucidated in c. elegans, the molecular details of that program, are virtually identical to everything we know that happens in all multi-cellular organisms, including humans," Mr. Shaham said.
With the worm as a laboratory, John Sulston developed techniques to study all of its cell divisions. He discovered that, in each worm, cells divided more often than appeared necessary to make a 959-cell adult. That is because some of those cells died during development. It was always 131 cells dying in every c. elegans at exactly the same points in every worm's growth. This observation led Mr. Sulston to conclude that some of the new cells are genetically programmed to die as a part of development.
Shai Shaman says Robert Horvitz then discovered key genes controlling this process. "That really nailed down the fact that there was a genetic program encoded in the organism's genes that told cells to commit suicide in response to different stimuli," he said.
One example of programmed cell death is the loss of the thick webbing between the fingers and toes of a human embryo. Mr. Shaham says an instance of programmed cell death gone awry is a cancer tumor, which is endless cell replication in an organ. "One of the tremendous insights of the work on cell death overall has been that, at the core of every cancer is a defect in programmed cell death. In order for a tumor to develop appropriately, it somehow has to inactivate cell death genes," he said.
The Swedish Nobel committee says the description of the genetic basis for cell reproduction and death has made it possible to identify related genes with similar functions in humans. It says understanding this process is important for medical research, and has shed light on the origin and development of many diseases.
The three researchers will receive the $1 million Nobel Medicine Prize at a December 10 ceremony in Stockholm.