Cancer gene

Gene Turns On Switch for Cancer

A common inherited gene carries with it a powerful cancer "on" switch. TGFBR1*6A predisposes one in eight people to developing certain forms of cancers and is found in 50 percent of metastatic liver tumors from colorectal cancer. Described in the October 5 issue of the Journal of the American Medical Association, a Northwestern study showed that the majority of liver metastases carrying the TGFBR1*6A gene acquire it during cancer progression. The gene has a dramatic impact on the growth of cancer cells in humans, said Boris Pasche, MD, PhD, assistant professor of medicine at the Feinberg School and lead researcher. "TGFBR1*6A may become an excellent target for new therapies for patients with colorectal cancer, especially those with liver metastases," reported Dr. Pasche, who discovered the gene in 1998.

Previous studies have shown that TGFBR1*6A appears in 14 percent of the general population and significantly increases breast, colon, and ovarian cancer risk. Until now, just how the gene contributes to cancer development has been largely unknown. Dr. Pasche and co-researchers found that TGFBR1*6A appears to bestow cancer cells with a dramatic growth advantage in the presence of TGF-beta, a potent, naturally occurring inhibitor of cell growth.

The researchers conducted genetic testing on DNA from cancerous tumors and other cancer cells and from normal tissues in 531 study participants with a diagnosis of head and neck cancer, colorectal cancer, or breast cancer. They found that *6A was acquired in 30 percent of colorectal cancer metastases; 3 percent of colorectal tumors; 2 percent of head and neck primary tumors; and in none of the study participants with breast cancer.