Firefly glow gene helps show effectiveness of experimental cancer drugs
TUESDAY 3 JUNE 2008
Scientists have developed a new way to track the effectiveness of blood-vessel-busting anti-cancer drugs in trials - using the gene that allows fireflies to glow.
The technique, called bioluminescence imaging (BLI), could allow researchers to determine whether a drug has succeeded in cutting off a tumour's blood supply.
Tumours need oxygen and nutrients to grow, so trick the body into 're-plumbing' blood vessels to feed them.
As a result, many new cancer therapies are designed to disrupt these new blood vessels, which are thought to be distinct from 'normal' blood vessels.
So researchers at the University of Texas (UT) Southwestern Medical Centre injected mice with human breast cancer cells that had been altered to carry the firefly gene.
The technique is not intended to be used for imaging tumours or diagnosing cancer in humans, but it potentially allows us to do much more efficient pre-clinical experiments.
- Dr Ralph Mason, professor of radiology and director, Southwestern Cancer Imaging Centre, Texas
Cells which carry the gene only emit light if they come into contact with a biological pigment called luciferin, so, after treating the mice with drugs, the scientists injected the mice with luciferin to see if it reached the tumour cells.
If the pigment reached the tumour's cells and the scientists' light-detecting equipment detected light emissions, this showed that the tumour's blood supply had not been destroyed and that the anti-cancer drug being tested was not working as desired.
Senior author Dr Ralph Mason, professor of radiology and director of the UT Southwestern Cancer Imaging Centre, commented: "What we've done is offer proof-of-concept that BLI may be an effective and cheaper method to assess drug development and effectiveness.
"The technique is not intended to be used for imaging tumours or diagnosing cancer in humans, but it potentially allows us to do much more efficient pre-clinical experiments."
The researcher noted that BLI could have advantages over magnetic resonance imaging (MRI) as it is cheaper and allows cells not accessible by MRI to be investigated.
He said: "Ultimately, the MRI is much more sophisticated and can do more, but BLI is very straightforward. It's perfect for evaluating new classes of drugs designed to cause acute vascular changes in tumours because the tests are inexpensive and easy to do.
"You need to do a lot of tests to optimise dosing, optimise repeat delivery and probably optimise the co-administration of other, more traditional drugs or therapies," he explained. "BLI provides an opportunity to do those tests cheaply and efficiently."
The technique is detailed in the Journal of the Federation of American Societies for Experimental Biology.
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