Ostermeier's team made the cancer-fighting switch by fusing together two different proteins. One protein detects a marker that cancer cells produce. The other protein, from yeast, can turn an inactive prodrug into a cancer-cell killer. "When the first part of the switch detects cancer, it tells its partner to activate the chemotherapy drug, destroying the cell," Ostermeier said.

In order for this switch to work, it must first get inside the cancer cells. Ostermeier said this can be done through a technique in which the switch gene is delivered inside the cell. The switch gene serves as the blueprint from which the cell's own machinery constructs the protein switch. Another approach, he said, would be to develop methods to deliver the switch protein itself to cells.

Once the switches are in place, the patient would receive the inactive chemotherapy drug, which would turn into a cancer attacker inside the cells where the switch has been flipped on.

Although many researchers are developing methods to deliver anti-cancer drugs specifically to cancer cells, Ostermeier said the protein switch tactic skirts difficulties encountered in those methods.

"The protein switch concept changes the game by providing a mechanism to target production of the anti-cancer drugs inside cancer cells instead of targeting delivery of the anti-cancer drug to cancer cells," he said.

Source: Johns Hopkins University