Molecular Imaging Sheds Early Light on Disease

ST. LOUIS, Mo., Nov. 27 -- Researchers at Washington University School of Medicine in St. Louis are developing methods to track molecular events in the body to diagnose disease long before symptoms appear and to predict the effectiveness of drug therapies. The research is under way at the School of Medicine's new Molecular Imaging Center at the Mallinckrodt Institute of Radiology. The Center is funded by a five-year $9.4 million grant from the National Cancer Institute.

"Molecular imaging combines the latest in imaging technology with the power of molecular biology," said David Piwnica-Worms, MD, Ph.D., a professor of radiology and molecular biology, and pharmacology and director of the new center.

"We believe that molecular imaging will one day enable us to diagnose specific molecular events of cancer, neurologic disease or inflammation earlier in the course of disease, and that this will help doctors identify the most effective therapy for individual patients."

Piwnica-Worms described molecular imaging and research being done at the Center during the 40th annual New Horizons in Science Briefing, sponsored by the Council for the Advancement of Science Writing, held in October at Washington University in St. Louis.

Investigators at the Center are using molecular imaging to study protein-protein interactions, immune cells attacking a tumor, and the course of a viral infection and its response to antiviral therapy. Other researchers are developing a means to noninvasively predict the effectiveness of particular chemotherapy drugs in patients with advanced lung cancer. The investigators are studying lung tumors for ways to image the activity of a protein that pumps certain anticancer drugs out of tumor cells, rendering the drugs ineffective for those individuals.

In a mouse model of cancer, scientists insert a gene for luciferase -- the enzyme produced by fireflies -- into tumor cells. When the modified cells are transplanted into mice, and the mice are injected with another firefly protein called luciferin, the cancer cells "light up." The technology provides a new way for scientists to study how tumors grow and spread.

Positron emission tomography (PET) is one example of molecular imaging technology already in use clinically. PET scans are used, for instance, to detect the spread of certain cancers. Patients are given a form of sugar -- glucose -- that contains a weak radioactive label. The labeled sugar is taken up more rapidly by tumor cells than by normal cells, because the tumor cells are growing at a faster rate. PET-scan imaging reveals this higher level of uptake, thereby providing a nonsurgical way to detect an otherwise hidden tumor.

Researchers at Washington University's Molecular Imaging Center are developing new applications for existing technologies, such as PET, and exploring new methods of molecular imaging using near-infrared fluorescence and bioluminescence probes.

For more information, visit: www.wustl.edu