Fireflies' glow helps UT Southwestern researchers track cancer drug's eff...( DALLAS May 29 2008 The gene that a...),Health

DALLAS May 29, 2008 The gene that allows fireflies to flash is helping researchers track the effectiveness of anti-cancer drugs over time.

UT Southwestern Medical Center researchers are among the first to show that a technique called bioluminescence imaging (BLI) can be used to determine the effectiveness of cancer drugs that choke off a tumors blood supply.

The technique requires a substrate called luciferin to be added to the bloodstream, which carries it to cells throughout the body. When luciferin reaches cells that have been altered to carry the firefly gene, those cells emit light.

Some cancer drugs, however, work by cutting off the blood supply to tumor cells. Given that luciferin is delivered via the vasculature, the researchers set out to determine the kinetics of luciferin delivery and whether BLI techniques could be used to gauge the effectiveness of drugs that destroy blood vessels that feed tumors.

They tested their theory in mice bearing human breast-cancer tumors. Before being introduced to the animals, the tumor cells had been transfected with the firefly gene, which becomes part of the cells as they divide and grow just like genetically modified, herbicide-resistant food crops.

For the study, researchers used BLI to monitor light emissions from tumors following administration of the luciferin. While the mice didnt visibly glow, the researchers used special light-detecting equipment to observe strong correlations between the amount of light emitted and the size of the tumor as it grew. Detected light emission, however, was severely reduced after the vascular-disrupting drug was administered.

What weve done is offer proof-of-concept that BLI may be an effective and cheaper method to assess drug development and effectiveness, said Dr. Ralph Mason, professor of radiology, director of the UT Southwestern Cancer Imaging Center and senior author of the study. The technique is not intende
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