Stopping coughs … and cancer?

Science News, March 14, 1998 by John Travis

Noscapine, a cough suppressant long used in South Africa, Japan, and Sweden, may someday help combat a much more serious ailment--cancer. Investigators have unexpectedly found that this drug can induce dividing cells to commit suicide and can shrink tumors growing in mice.

"We're the first to find that this agent can be used as a cancer drug. A lot of companies are contacting us," says Keqiang Ye of the Emory University School of Medicine in Atlanta.

Ye and his colleagues, who describe their work in the Feb. 17 Proceedings of the National Academy of Sciences, believe that noscapine exerts its anticancer effects by binding tubulin, a protein that forms the cellular filaments called microtubules. Several other known cancer drugs, such as taxol, function similarly. While some of these drugs inhibit microtubule assembly and others stabilize the filaments, they all apparently interfere with a cell's ability to divide.

In the case of noscapine, this interference causes the cell, which is fruitlessly trying to divide, to kill itself. When the investigators gave noscapine to mice with solid tumors, including animals implanted with human breast or bladder tumors, the drug dramatically shrank the cancers. For example, a 3-week regimen of noscapine reduced the size of human breast tumors by 80 percent. Some tumors were eliminated.

Noscapine may be a particularly attractive cancer drug, says Ye, because it can be taken orally and has a proven safety record. Many of the other cancer drugs that bind tubulin must be injected and produce severe side effects, he notes.