Fluorescent probes may permit monitoring of chemotherapy effectiveness, Stanford s...( STANFORD Calif. Going out like a br...),Health

STANFORD, Calif. Going out like a brilliant flame is one way to get attention. If physicians could watch tumor cells committing a form of programmed suicide called apoptosis, a desired effect of workhorse cancer treatments such as chemotherapy and radiotherapy, they could more quickly pick the most effective treatment. Now scientists at the Stanford University School of Medicine have found a way to do just that, by lighting up cells as they die.

Apoptosis is a carefully orchestrated sequence of intracellular events that leads to the cell's death. "The cell takes itself apart in a finite series of steps," said Matthew Bogyo, PhD, associate professor of pathology and of microbiology and immunology, and a member of the Stanford Cancer Center.

Bogyo is senior author of a study to be published online July 13 in Nature Medicine in which he and his Stanford colleagues demonstrated in mice that it is possible to noninvasively image the degree of apoptosis occurring in living animals' tumors, and thereby to gauge the effectiveness of apoptosis-inducing treatments. Several steps still remain before it can be determined whether this diagnostic method is safe for use in humans.

Apoptosis occurs all the time in healthy bodies. Cells have this suicide system in place to deal with viral infections, or just to complete their normal life cycle. Cells lining the gut, for example, or immune cells in the spleen and thymus are meant to live only a couple of days. "You lose three-quarters of a million cells per second in your body due to apoptosis," noted Guy Salvesen, PhD, director of the program on apoptosis and cell-death management at the Burnham Institute for Medical Research, in La Jolla, Calif.

But apoptosis is also a check against unwanted cell division, as occurs during tumor growth, said Salvesen, who collaborates with Bogyo on various research projects but did not participate in this study. "Cancer cells have to learn to do two
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