Bright Idea Could Doom Cancer and Viruses, Say Purdue Scientists

WEST LAFAYETTE, Ind. Cancer and viruses may someday find themselves blinded by the light of therapies based on recent Purdue University chemistry research.





"That's the reason cancer patients often lose their hair," Morrison said. "Hair cells, like many others in the patient's body, are also destroyed by these platinum-based chemotherapy drugs. So for a long time, physicians have sought other substances they have more control over. If we had a drug we could activate when it reached a certain place in the body -- and nowhere else --it would reduce the stress on the rest of a cancer patient's system."

Morrison's group experimented with several different chemical complexes that use rhodium, a rare metal, instead of platinum. Eventually they found one compound that was able to damage DNA in living cells in a manner similar to platinum chemotherapy drugs, but with one exception -- it remains benign until irradiated with a light beam.

"Anticancer therapies could, in theory, be developed using such photo-activated rhodium complexes," Morrison said. "The interior of the body is dark, but it might be possible to thread a fiberoptic cable through the arteries and flood a tumor with light. Some lasers are also capable of shining through tissue without damaging it, and they might also be candidates for light delivery."

The compound -- known as DPPZPHEN, an abbreviation of its long chemical name -- also has potential as an antiviral or blood sterilizing agent because it is lethal to any nucleic acid it encounters, including the RNA found in viruses.

"Our study also found the rhodium complex capable of rendering the Sindbis virus inert," Morrison said. "Since blood cells and platelets do not themselves have nucleic acid, they are safe from the compound. But it is potentially possible to purify blood of foreign organisms and viral particles with the rhodium complex and light exposure before it is used in transfusions. It could make for a safer blood supply."

Each of these applications, however, is likely years from development, Morrison said.

"We have only proven in principle that such therapies are possible," he said. "But our experiments have only been on tumor cells in the laboratory, not in living animals. It will require further research to determine how rhodium-based drugs could be created."

Some of that research will need to cover issues that Morrison's group has considered, though not addressed, such as the specific frequencies of light to be used and the compound's level of toxicity.

"Another issue is how to keep these compounds from getting scavenged up by the blood before they reach their targets, which tends to happen because of their adhesion to blood proteins," Morrison said. "But I believe the results are promising for the future of the fight against cancer and viruses, and I hope other groups will continue the work we have begun."


Morrison and Kuhn are associated with the Purdue Cancer Center. One of just eight National Cancer Institute-designated basic research facilities in the United States, the center attempts to help cancer patients by identifying new molecular targets and designing future agents and drugs for effectively detecting and treating cancer.

Source: Purdue University

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