Summer 2017

Cancer-Fighting Colors

A pigment in red peppers, butternut squash and other foods might inhibit the growth of cancer cells.

Although nicotine, the addictive ingredient in cigarettes, does not cause cancer—you can blame that on tar and other chemicals—it does have the ability to accelerate the growth and spread of lung tumors. Nicotine binds to a specific receptor on the surface of lung cells, causing the growth of new cells and blood vessels—two hallmarks of cancer—and boosting production of the receptor. With more receptors available for nicotine to bind to, lung cancer cells in smokers get an even stronger signal to keep growing and spreading. But now Friedman professor Xiang-Dong Wang, N92, has found that the red pigment beta-cryptoxanthin (BCX) appears to counteract this effect.

Researchers knew eating such BCX-rich foods as sweet red peppers, oranges and butternut squash is associated with a lower risk of lung cancer in smokers. So Wang, director of the Nutrition and Cancer Biology Laboratory at the Human Nutrition Research Center on Aging, and his colleagues wanted to study how that might work at the molecular level. Looking at mice and cell models of human lung cancer for a study published in Cancer Prevention Research, they demonstrated that BCX causes cells to decrease the number of  nicotine receptors, which may dampen cancer cell growth. When the researchers administered daily doses of BCX to mice before and after they injected the rodents with a nicotine-derived carcinogen, they found that the mice had fewer lung tumors than a control group that didn’t get BCX.

BCX’s inhibition of the receptor may also play a role in keeping cancer from spreading. In order to metastasize, malignant cells need to move freely about the body. Wang’s team treated human lung cancer cells that have these receptors in a lab dish with BCX, and found that they migrated less than untreated ones. Previous studies from Wang’s lab suggest that BCX can slow the growth of lung tumors and decrease lung inflammation in animal models.

This better understanding of BCX’s molecular mechanism could lead to dietary recommendations for smokers, patients with lung cancer and lung cancer survivors, Wang said.

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