April 24, 1996 in Nation/World

Scientists Engineer Cancer Bomb Genes Would Destroy Only Cancer Cells, Not Healthy Tissue

Associated Press
 

Scientists fighting cancer have engineered what they call the first genetic time bomb, set to go off inside tumor cells when they blow their cover by producing telltale proteins.

The approach is intended to deliver its killing force to cancer cells with pinpoint accuracy while sparing the healthy tissue around them.

The idea is still in the test tube and probably years away from human use. It is notable for its novelty, but whether it will eventually lead to a cancer cure, as its developers hope, remains to be seen.

Ordinary chemotherapy uses a scattershot approach: Toxic medicines kill not only cancer cells but plenty of innocent bystanders, too. Many scientists have been trying to identify landmarks that make tumors unique, then tailor medicines that zero in on them.

The gene bomb scans the inner-most workings of the renegade cancer cells looking for proteins that only they make.

“As with any bomb, it has an explosive part and a trigger,” said Luis da Costa, a research fellow at Johns Hopkins University.

“You can put this bomb into a cell, and if it is normal, nothing happens,” he said. “We engineered the trigger so it can only be pulled by a cancer protein. This will make the bomb go off and kill the cancer cell.”

Da Costa described the innovation Tuesday at the annual meeting of the American Association for Cancer Research.

While researchers have talked excitedly for years about using gene therapy to cure cancer and other ills, they are confounded by one serious drawback: How do you get the killer genes into the cells you want to eliminate?

One strategy is to use viruses as Trojan horses to carry them in. But cancer cells seem especially hard to penetrate. In the clump of tumor cells, only a few may absorb the transplanted genes. Even if these die, the others survive and spread.

However, da Costa’s approach may help sidestep this problem, too.

The bomb may kill not only the cell it blows up, but those around it as well - in effect, shrapnel.

In da Costa’s view, another beauty of the idea is its potentially wide applicability.

“A variety of different cancer proteins could be used to pull the trigger,” he said.

© Copyright 1996 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.


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