Rat research may slow growth of brain tumors

WASHINGTON -- An aggressive form of brain cancer secretes a chemical that kills nearby cells and carves out a path for its own growth, say researchers studying the disease in rats.

Their findings could point to a way of slowing the growth of the disease in humans using drugs already available.

The research team, led by Dr. Maiken Nedergaard of New York Medical College in Valhalla, N.Y., found that in the brain cancer known as glioma, cancer cells secrete a chemical called glutamate.

Glutamate is normally present in the brain, which uses it to transmit messages between cells. Excess amounts cause degeneration of brain cells.

"In essence, our study shows that gliomas actively secrete a compound, glutamate, that is toxic to surrounding neurons, and thereby utilize a unique way of promoting their own growth by killing their surroundings," explained Nedergaard via e-mail from Denmark.

"Our data suggest that the more malignant the glioma cells are, the more glutamate they release," she said.

"Other cancer types do not have this type of aggressive behavior. I think that the exciting part of our study is that it may give new hope to treatment since gliomas respond poorly to chemo-therapy and radiation," she added.

Drugs that block the release of glutamate are already in use in other diseases, such as Parkinson's disease, and could be added to the treatment of patients with glioma, Nedergaard said.

"We found that tumor growth was reduced 30 percent to 60 percent depending on the type of gliomas," Nedergaard said of the studies.