New evidence suggests antioxidants may have a future in cancer treatments
Antioxidants, once thought to do more harm than good in many cancer patients, may help stop the growth of mesothelioma and malignant tumors, according to new research.
The findings by a team of researchers at the Kimmel Cancer Center in Philadelphia provide the first “genetic proof” that oxidative stress caused by the loss of a specific cell protein is an important factor in tumor growth, said Michael P. Lisanti, professor of cancer biology at Jefferson Medical College of Thomas Jefferson University.
Lisanti said antioxidant drugs currently being used to treat other diseases, including lung disease and malaria, can be used to prevent and treat cancers by inhibiting tumor growth.
“This means we need to make anti-cancer drugs that specially target this type of oxidative stress,” he said.
In the recent study, published online in Cancer Biology & Therapy, Lisanti and his colleagues traced the origins and biological mechanism of oxidated stress in breast cancer patients. They found that an absence or deficiency of a protein called Caveolin-1, or Cav-1, induces oxidative stress in certain tissue cells. That stress and the resulting autophagy — a process in which cells cannibalize their proteins for nutrients — function as metabolic energy for tumors.
The researchers report that the loss of Cav-1 led to four-fold increases in both tumor mass and tumor volume.
Some antioxidants, such as beta carotene, are sold as dietary supplements. Certain foods — beans, apples, strawberries and cherries, for example — are known to fight oxidative stress, which is thought to be a factor in neurodegenerative diseases like Alzheimer's, Parkinson's and Huntington’s. Oxidative stress has also been linked to cardiovascular disease and chronic fatigue syndrome.
Although several antioxidant-based drugs are currently being used to treat diabetes and malaria, they have not been considered an effective treatment for cancer because they can reduce the effects of chemotherapy, which increases oxidative stress.
“Antioxidants have been associated with cancer-reducing effects — beta carotene, for example — but the mechanisms, the genetic evidence, has been lacking,” Lisanti said. "Now that we have genetic proof that mitochondrial oxidative stress is important for driving tumor growth, we should reconsider using antioxidants… as anti-cancer agents.”