Nearly 30,000 men die each year from prostate cancer that has spread to other organs of the body. Being able to predict whether the disease is likely to spread, or metastasize, in a particular patient would help doctors design a better course of treatment. To that end, research published today in the journal Nature could help. Scientists report that high levels of activity in a gene known as EXH2 mark the most aggressive cancer cells.

Arul M. Chinnaiyan of the University of Michigan Medical School and his colleagues utilized DNA microarrays to assess the activity of genes in both localized and metastatic prostate cancer. They found 55 genes that exhibited greater activity in the metastatic samples than in the localized cases. The most pronounced difference, the team found, was in EZH2. (The image at left shows prostate cancer cells stained for EZH2 protein (left) and DNA microarray data (right). Red squares identify genes that are active in metastatic prostate cancer, while green squares indicate genes that are repressed.)

The scientists next analyzed more than 1,000 prostate samples (including cancerous tissue, tissue with benign cell changes and normal tissue) to measure levels of the EZH2 protein. They found that the amount of EZH2 protein produced increased as the disease advanced. Says study co-author Mark A. Rubin of Brigham and Women's Hospital, "We found EZH2 protein expression to be significantly better at predicting clinical outcome than any other factor." Chinnaiyan notes, however, that "at this point, it's unclear whether the gene plays a role in cancer's development or is simply an indicator of lethal progression."