Teams of scientists at Johns Hopkins and several other research labs have isolated a gene responsible for a rare inherited form of colon cancer. On the way, they also found the suspected triggers for the more common forms of the disease. The discoveries, reported in the journals Science and Cell, illustrate the promise of progress to come in mapping out the human genome.
Several years ago, Bert Vogelstein of the Hopkins Oncology Center found a series of "tumor suppressor genes" that act like brakes, controlling cell growth. Deactivated or damaged, these genes can cause a cell to grow into a tumor. One, p53, when altered, can turn a benign tumor into a cancer. Now his lab says a malignant colon cell collects mutations in other genes as well, demonstrating that cancer is a multi-step process.
Working with teams led by Curt Harris of the National Cancer Institute, Ray White of the Howard Hughes Medical Institute at the University of Utah and the Tokyo Cancer Institute, Dr. Vogelstein's team has isolated the gene causing familial adenomatous polyposis (FAP). Inheriting a mutated version of this gene is a crucial first step in the conversion of a normal colon cell into a cancerous one, Dr. Vogelstein says. The same gene turned up in tumor cells from patients suffering more widespread forms of colon cancer, indicating that once damaged, it becomes a switch helping to activate all colon cancers.