Antioxidants May Help Fight Mesothelioma

New research from a Philadelphia cancer center suggests antioxidants may be another important tool in the fight against malignant mesothelioma.

Consumers know antioxidants, such as beta carotene, as dietary supplements which can fight oxidative stress at the cellular level. Certain beans, blueberries, apples, cranberries, strawberries, cherries and plums are just some of the foods that are high in antioxidants. But there are also several antioxidant-based drugs that have a similar effect on cells and are currently being used to treat conditions such as lung disease, diabetes and malaria.

Now, researchers at Thomas Jefferson Hospital’s Kimmel Cancer Center in Philadelphia have found evidence that these drugs may also be effective against cancers, such as mesothelioma. The team showed that the loss of a tumor-suppressing protein known as Caveolin-1 leads to tumor growth and is an important predictor of cancer outcomes. Breast cancer patients found to be missing the Caveolin-1 protein had only a 10 percent chance of surviving for 5 years, whereas those who did have the protein had a 75 percent chance of survival.

Loss of the Caveolin-1 protein leads to oxidative stress in mesothelioma cells, which produces ‘fuel’ for tumor growth. Because antioxidants fight this stress, and cut off this fuel supply, the researchers theorize that treating mesothelioma patients with antioxidant medications might be one way to stop the growth of their tumors. Currently, antioxidants are not typically used to treat mesothelioma and other cancers because it is commonly believed that they could counter the effectiveness of chemotherapy drugs, which cause oxidative stress.

“This study provides the necessary genetic evidence that reducing oxidative stress in the body will decrease tumor growth,” said lead researcher Michael P. Lisanti, M.D., Ph.D., professor of cancer biology at Jefferson Medical College.”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.”

Some of the drugs shown to reduce oxidative stress include the diabetes drugs metformin, a malaria medication called chloroquine and a third agent called N-acetyl cysteine. In the future they could be used as part of a multi-modality treatment approach to mesothelioma, which is notoriously difficult to treat.

The study’s findings were published in the online February 15 issue of Cancer Biology & Therapy.

Sources:

Trimmer, Casey at al, “Caveolin-1 and mitochondrial SOD2 (MnSOD) function as tumor suppressors in the stromal microenvironment: A new genetically tractable model for human cancer associated fibroblasts”, Cancer Biology & Therapy, February 15, 2011. Volume 11, Issue 4
“Jefferson Researchers Provide Genetic Evidence that Antioxidants Can Help Treat Cancer”, Feb. 15, 2011, news release from Thomas Jefferson University, via EurekAlert website.