Fluorescent compound sticks to diseased cells, making them easier to spot, study says
MONDAY, Dec. 8 (HealthDay News) -- A substance that glows and sticks to viable cancer cells, making them easy for doctors to spot, has been successfully tested in mice, researchers report.
The man-made compound, a combination of the breast cancer drug Herceptin and a fluorescent molecule called BODIPY, binds to the HER2 protein contained on the surface of some breast cancer cells. It only glows, or fluoresces, when inside living cells -- an improvement from most fluorescent imaging compounds that always glow and make it difficult for doctors to tell viable tumor cells from normal tissue or dead or damaged tumor cells.
The findings, made by researchers at the U.S. National Cancer Institute, were published online Dec. 7 in Nature Medicine.
"Imaging compounds designed by our concept may have applications in the clinic," lead researcher Dr. Hisataka Kobayashi of the Molecular Imaging Program of NCI's Center for Cancer Research, said in a news release issued by the institute. "These compounds may allow clinicians to monitor a patient's response to cancer therapy by allowing them to visualize whether a drug hits its target and whether hitting the target leads to shrinkage of the tumor. With additional research and extensive testing in humans, these compounds may also be adapted for use in endoscopy procedures and for use as a surgical aid to improve removal of tumors."
The compound should be able to be engineered to target specific types of cancer cells.
"Our design concept is very versatile and can be used to detect many types of cancer," Kobayashi said. "Unlike other activatable fluorescent compounds, our compound consists of a targeting agent and a fluorescing agent that act independently. We can target the fluorescing agent to different types of cancer cells by using any antibody or molecule that is internalized by the targeted cells after it binds to the cells' surface proteins."
In their study, the team injected either their compound or one that always fluoresces in mice with HER2-positive breast cancer tumors that had spread to their lungs. A day later, the "activatable" compound was found only in lung tumors, while the "always on" one glowed on lung tumors, normal lung tissue and the heart.
The findings showed the compound was 99 percent accurate in tumor detection for HER2-positive tumors, while the "always on" control was accurate less than 85 percent of the time.
In another experiment, the researchers re-engineered the compound so it successfully detected live ovarian cancer cells that had spread to the tissue lining the walls of the abdomen in mice.
The U.S. National Cancer Institute has more about breast cancer.
-- Kevin McKeever
SOURCE: U.S. National Institutes of Health, news release, Dec. 7, 2008
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