For over 10 years, Wafik S. El-Deiry, MD, PhD, Professor of Medicine, Genetics, and Pharmacology at the University of Pennsylvania School of Medicine, has been pursuing a cancer-targeting molecule called TRAIL and its molecular partners.
TRAIL is normally produced by immune cells and curtails tumor spread by binding to a specialized receptor on a tumor's surface.
“However, in cancer patients who often have suppressed immunity, and for reasons we still don't understand, there isn't enough TRAIL being produced, so tumors are not suppressed,” explains El-Deiry, who is also Co-Program Leader of the Radiation Biology Program for the Abramson Cancer Center at Penn.
Most recently, El-Deiry and colleagues demonstrated for the first time a link between TRAIL's receptor and cancer susceptibility, as reported online December 13, 2007 in the Journal of Clinical Investigation in advance of the January 2008 print issue. Unexpectedly, they also found a connection – via Trail – between inflammation and cancer susceptibility.
Mice engineered without the TRAIL receptor on their cells versus healthy controls developed larger and more tumors in their livers and other organs after being challenged with a chemical carcinogen or radiation. The team also bred TRAIL receptor knock-out mice with mice genetically engineered to get B-cell lymphomas that metastasize to the liver. Their offspring displayed more liver tumors compared to controls. “This is the first direct in vivo evidence that loss of the tumor death-inducing TRAIL receptor confers cancer susceptibility,” says El-Deiry.
When intact, TRAIL and its receptor decrease the influx of inflammatory cells and molecules that can lead to cancer. New models of cancer have suggested a link between inflammation and cancer in the last five years, and El-Deiry is in the early stages of trying to understand this connection with respect to the TRAIL pathway.