Johns Hopkins Kimmel Cancer Center scientists identified 200 genetic mutations responsible for most breast and colon cancers, findings that may lead to new tests for identifying cancer, and possibly to new therapies.
Most of the variations identified by Hopkins in the Thursday issue of Science Express were not previously associated with tumor origin, growth, spread or control, said researcher Kenneth Kinzler, with the Kimmel Center.
“Cancer is basically a genetic disease. It’s not caused by a virus or a toxin. It’s basically your own cells gone bad,” Kinzler said. “We are convinced that this kind of study will provide one of the best road maps possible for beating cancer. Who would pass up the opportunity to read the enemy’s game plan?”
Cancer cells shed their DNA into bodily fluids and combinations of these mutations can be used as genetic markers to identify cancerous growth, he said.
Already well-known genetic mutations have proven effective markers for some types of cancer, but this genome “encyclopedia” gives researchers more targets to look for. Genetic mutations have also yielded effective treatments as in the use of Herceptin to target a breast cancer cell receptor made by the “Her2-neu” gene.
The Hopkins researchers found the number of genes that were altered in breast and colorectal cancer genomes surprising. “We expected to find a handful of genes, not 200,” said Tobias Sjöblom, a lead author and postdoctoral fellow at Kimmel.
The team examined 11 samples each from breast and colon cancers, and compared mutated genes with healthy tissue, to separate true mutations from “typos” or minor changes which do not affect the genetic “instructions.”
The Hopkins team also found, on average, 100 mutated genes in each cancer, with at least 20 identified as crucial for tumor formation. “Each cancer has a different blueprint,” researcher Dr. Victor Velculescu said. “No two patients are identical.”
The Hopkins study should simplify breaking down other cancers’ codes, Kinzler said.
Researchers from the University of Maryland Greenebaum Cancer Center participated in the study.
