Antioxidant Drugs Beneficial for Limiting Tumor Growth in Cancers, May Fight Effects of Mesothelioma-Causing Asbestos
Researchers at Thomas Jefferson Hospital’s Kimmel Cancer Center report that they have found genetic evidence that antioxidant drugs currently used to treat lung disease and the common cold can also be beneficial for treating cancers. Antioxidants fight mitochondrial oxidative stress which has been shown to drive tumor growth. Stopping tumor growth and preventing metastasis in cancers, especially mesothelioma which is highly aggressive and is resistant to many standard cancer treatments, is critical for increasing survival in patients.
Treating a limited area of cancer is easier, and offers more treatment options, than trying to treat cancer that has spread, or metastasized, to several sites or throughout the body. Pleural mesothelioma is a form of lung cancer that is almost always caused by asbestos exposure and is most commonly found in the outer lining of the lungs. Once the cancer cells have spread beyond the original location, the mesothelioma is considered advanced and the survival time varies from 4 – 18 months.
The researchers found that a loss of Caveolin-1 (Cav-1), a protein that functions as a tumor suppressor, actually induces mitochondrial oxidative stress, which in turn fuels tumor growth. Lead researcher Michael P. Lisanti, M.D., Ph.D., professor of cancer biology at Jefferson Medical College of Thomas Jefferson University and member of the Kimmel Cancer Center at Jefferson said, “This means we need to make anti-cancer drugs that specially target this type of oxidative stress.”
Their findings, that were published in Cancer Biology & Therapy, report that “the loss of Cav-1 increases mitochondrial oxidative stress in the tumor stroma, increasing both tumor mass and tumor volume by four-fold, without any increase in tumor angiogenesis.”
Antioxidants have been associated with cancer reducing effects. Exposure to various environmental factors, including tobacco smoke and asbestos, known to cause lung cancer, mesothelioma and asbestosis, can lead to free radical formation. Free radical damage may lead to cancer, but antioxidants, which are found naturally in fruits and vegetables, nuts, grains, and some meats, poultry, and fish, are often described as “mopping up” free radicals and protecting against cancer.
Lisanti said that currently, anti-cancer drugs targeting oxidative stress are thought to reduce the effectiveness of certain chemotherapies and are not used in cancer treatment. However, he added “Now that we have genetic proof that oxidative stress and resulting autophagy are important for driving tumor growth, we should re-consider using antioxidants and autophagy inhibitors as anti-cancer agents.”
