Genetic switch wipes out tumors in mice

The gene Apc is like a club bouncer: It keeps cellular parties from growing out of control. By switching Apc on, researchers turned swelling mobs of mouse cancer cells (above) back into normal intestinal tissue (below).

Scientists knew Apc was involved in stifling tumor formation because most colon cancers find a way to turn the gene off. Lukas Dow, a cancer biologist at Weill Cornell Medical College in New York City, and colleagues investigated Apc’s role by genetically engineering mice with a kind of Apc on/off switch.

Shutting the gene off made puffy polyps bud in the animals’ colons, the researchers report in the June 18 Cell. (The images show cells extracted from the mice.) Switching Apc on again made the frenzied cells morph back into healthy gut tissue, which contains intestinal cells (below, green) and clusters of stem cells (below, pink). The polyps disappeared.

Apc quiets signals that rev up cell growth, Dow says. Without the gene keeping growth signals under control, cells go berserk. Eventually, they can get aggressive and muscle their way throughout the body, he says. “And that’s what kills patients.”

If scientists can dial down growth signals in human colon cancers, Dow says, tumors may wither away — just as they did in mice.