Cancer Drugs' Effectiveness Tracked by Glow of Fireflies

A gene that can produce a flash in fireflies has been used to track the effectiveness of anti-cancer drugs by researchers at UT Southwestern Medical Center.

In a first of its kind effort, researchers have now shown that a technique called bioluminescence imaging (BLI) can be used to determine the effectiveness of cancer drugs that obstruct the blood supply to a tumor.

In this technique, the scientists make use of a substrate called luciferin to be added to the bloodstream, which carries it to cells throughout the body. When luciferin reaches the cells that have been altered to carry the firefly gene, these cells are found to emit light. However, there are a few cancer drugs, which work by cutting off the blood supply to tumor cells.

As we know that luciferin is delivered via the vasculature, the researchers wanted to find out the kinetics of luciferin delivery and if BLI techniques could be used to gauge the effectiveness of drugs that destroy blood vessels that feed tumors.

The researchers tested the 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 carrying out the study, firstly BLI was used to monitor light emissions from tumors, followed by administration of the luciferin. As the mice didn't visibly glow, the researchers resorted to special light-detecting equipment for observing strong correlations between the amount of light emitted and the size of the tumor as it grew. However, the detected light emission was severely reduced after the vascular-disrupting drug was administered.