Written by Chrystal Moulton, Staff Writer. Study shows that Vitamin C can cause death of malignant mesothelioma cells at concentrations that are safe and well tolerated by healthy mesothelial cells.

Cancer is characterized by uncontrolled cell growth leading to tumors that put stress on vital organs. Over the years, various medicines and procedures have been developed to ameliorate the symptoms related to cancer development and prevent tumor growth and spread. However, long before chemotherapeutic drugs and radiation treatment, researchers hypothesized that vitamin C or ascorbate (an essential nutrient for human health) if used in high doses at the site of the tumor could not only prevent the spread of the tumor, but reduce its size. (1-4) Vitamin C has already shown benefit for treating various cancers. (5-7) However, the use of vitamin C for mesothelioma has yet to be tested. In the current experiment, researchers tested the effect of vitamin C on malignant mesothelioma cells in vitro. Researchers hoped to find a mechanism by which vitamin C could prevent tumor growth and stop the spread of mesothelioma in patients diagnosed with this form of cancer. (8)

Samples of malignant mesothelioma cells were gathered from tissue samples of two types of mesothelioma: epitheliod (REN cells) and sarcomatoid (MM98 cells) mesothelioma. Each of these subtypes represent a specific mutation that makes it especially difficult to treat. Researchers also gathered samples of healthy mesothelial cells in order to compare the effects of vitamin C on healthy mesothelial cells versus cancerous mesothelial cells.

Results showed that vitamin C was significantly more toxic to both subtypes of malignant mesothelioma compared to healthy mesothelial cells. In other words, after 24 hours of exposure to ascorbate, researchers found that the concentration of vitamin C required to kill both types of malignant cancer cells was about 4 times less than the concentration toxic to healthy mesothelial cells. (See Table 1)  In another test, they found that 1 hour of exposure to 1mM of vitamin C resulted in maximum apoptosis in malignant mesothelioma cell lines. Cell death continued during 1 hour of exposure in malignant mesothelioma cells at a maximum dose of 10mM of vitamin C. In normal mesothelial cells, 1 hour of exposure to 9mM of vitamin C was toxic to the healthy cells. Furthermore, researchers found that vitamin C promoted production of peroxide outside the cell as well as production of superoxide within the malignant mesothelioma cells at a higher rate than normal mesothelial cells.

In all, researchers discovered that vitamin C could be toxic to malignant mesothelioma cells at concentrations tolerated by healthy cells. This is particularly encouraging news since treatment for mesothelioma is extremely limited and difficult. In another study performed in healthy individuals, results demonstrated that oral supplementation with 30mg vitamin C produced on average about 8.6mM of ascorbate in plasma. (9) More studies are needed to verify a therapeutic dose of vitamin C for mesothelioma in human trials.

Source: Ranzato, Elia, Stefano Biffo, and Bruno Burlando. “Selective ascorbate toxicity in malignant mesothelioma: a redox Trojan mechanism.” American journal of respiratory cell and molecular biology 44.1 (2011): 108-117.

Posted July 9, 2015.

References:

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   8. Ranzato E, Biffo S, Burlando B. Selective ascorbate toxicity in malignant mesothelioma: a redox Trojan mechanism. Am J Respir Cell Mol Biol. 2011 Jan;44(1):108-17.
   9. Levine M, Conry-Cantilena C, Wang Y, et al. Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance. Proceedings of the National Academy of Sciences of the United States of America. 1996;93(8):3704-3709.