Vitamin C halts growth of aggressive forms.

• Position: Colorectal Cancer

High levels of vitamin C kill certain kinds of colorectal cancers in cell cultures, according to a study from a team of researchers, whose findings suggest that scientists one day could harness vitamin C to develop targeted treatments.

Colorectal cancer is the third most common cancer diagnosed in the U.S., with about 93,000 new cases each year. Around half of those cases harbor mutations in the KRAS and BRAF genes; these forms of the disease are more aggressive and do not respond well to current therapies or chemotherapy.

In the study, researchers from New York-Presbyterian Hospital/Weill Cornell Medical College; Cold Spring Harbor (N.Y.) Laboratory; Tufts Medical Center, Medford, Mass.; Harvard Medical School, Boston, Mass.; and Johns Hopkins Kimmel Cancer Center, Baltimore, Md., found that high doses of vitamin C--roughly equivalent to the levels found in 300 oranges--impaired the growth of mutant KRAS and BRAF colorectal tumors in cultured cells. The findings could lead to the development of new treatments and provide critical insights into who would most benefit from them.

The conventional wisdom is that vitamin C improves health in part because it can act as an antioxidant, preventing or delaying some types of cell damage. However, Lewis Cantley--director of the Cancer Center and professor of oncology research at Weill Cornell--and his colleagues discovered that the opposite is true in regards to high-dose vitamin C's therapeutic effects for the KRAS and BRAF forms of colorectal cancer--they occur as a result of inducing oxidation in these cancer cells.

In an oxygen-rich environment such as human arteries, a fraction of vitamin C, also called ascorbic acid, becomes oxidized and is transformed into a new compound called dehydroascorbic acid (DHA). Scientists have known for some time that a specific membrane protein, known as glucose transporter GLUT1, enables both...