Cow Milk Protein Slows Breast Cancer Cell Growth

A protein found in cow’s milk slowed the growth of human breast cancer cells in laboratory tests, a scientist says.

The growth-inhibiting protein, known as MDGI, is one of a family of such proteins, said Ronald Gorewit, a Cornell University animal science professor.

Unlike other mammals, cows do not get breast cancer, Gorewit said.

“Nobody’s ever had a handle on why,” he said. “One theory is that there are proteins like MDGI that inhibit the mutations of cancer genes.”

Gorewit said no human studies are being done, and it is too early to know how MDGI would affect people.

MDGI, which stands for mammary-derived growth inhibitor, was discovered in 1985 by Richard Grosse, a German molecular biologist and biochemist. Grosse, who has been working with Gorewit, found the protein in high concentrations in cows’ mammary tissue, where its role is apparently to tell cells when to stop growing and start producing milk.

Gorewit said the protein may also stop potentially cancerous cells from becoming cancerous.

Barbara Vonderhaar, a breast cancer researcher at the National Cancer Institute in Bethesda, Md., called Gorewit’s findings “potentially interesting but very, very preliminary.”

Breast cancer kills about 44,000 women annually in the United States.

The research is funded by Cornell’s College of Agriculture and Life Sciences.