First Steps

Watching for signals
(continued)

When it is overexpressed - say a person's cells have six copies of the HER-2 gene instead of the normal two - cell surfaces have thousands of extra growth factor receptor sites, all ready, eager and waiting to grow, grow, grow when hooked up with the right protein. When HER-2 is overexpressed in women, it contributes to the development of an aggressive form of breast cancer. About 25 percent of women with breast cancer and 15 percent of people with lung and prostate cancer overexpress HER-2.

Herceptin, which was developed three years ago, keeps HER-2 from telling breast cancer cells to divide. But it doesn't work in some patients and causes cardiac problems in others. Building a better inhibitor - "a better mousetrap," as Carraway puts it - would be of benefit.

"We believe HER-2 sends several signals to a cell, but only one of these affects tumor growth," he said. "If we could design a drug that affects only that pathway, we could stop breast cancer cells from growing without harming the patient's heart in the process."

And maybe, stop other cancer growth mechanisms as well. It's a long, complicated process, but basic scientists at the UC Davis Cancer Center are up for the challenge.