In a new study in PNAS, researchers at the University of Missouri describe their use of a compound found in tea leaves to deliver irradiated gold nanoparticles to solid tumors, while getting around the barriers of the tumor microenvironment that can hinder efforts to expose cancer cells to treatment. "It's actually gold salt," says the Columbia Daily Tribune's Janese Silvey. "Mixed with tea, the gold breaks down into nanoparticles. The research team discovered that an injection of radioactive gold nanoparticles coated with a chemical from tea shrinks fast-growing prostate tumors in mice by 70 percent to 80 percent." Radioactive gold nanoparticles have been known to kill cancer cells, but the problem is that they don't target cancer cells specifically — they kill everything they touch, Silvey says. Three years ago, the university's Kattesh Katti found that a compound in tea leaves could coat the gold nanoparticles and keep them from spreading radiation throughout the body. This compound, epigallocatechin-gallate, is also attracted to prostate tumor cells, so it can deliver the gold nanoparticles straight to the tumor. "The gold has a half-life of 2.7 days, so the radioactivity from a dose would be gone in about three weeks," Silvey adds.
The researchers plan to start testing the delivery system on dogs, and then move on to humans. If successful, a treatment could be available in five years, Silvey says.