Nature: Antioxidants May Be Melanoma Metastasis Promoters

A group of scientists at the Children's Research Institute at UT Southwestern (CRI) has recently found that, compared to normal cells, cancer cells benefit much more from antioxidants, raising concerns about taking dietary antioxidants supplements by cancer patients. Their study was performed on the specific mice that had been transplanted with human melanoma cells from patients. Previous studies have demonstrated that the melanoma cell metastasis in these mice can predict their metastases in a patient's body.

Metastasis is a process that the cancer cells spread to other parts of the body from the primary site, leading to the death of most cancer patients. The research team found that when mice were given anti-oxidants, the spread of cancer was faster than that of mice without antioxidants. The study was published online in Nature, entitled Oxidative stress inhibits distant metastasis by human melanoma cells.

People already know that the spread of cancer from one part of the body to another part is an inefficient process, and the vast majority of cancer cells entered into the bloodstream are unable to survive, for the highly oxidative environment and exposure to immune cells.

“We discovered that metastasizing melanoma cells experience very high levels of oxidative stress, which leads to the death of most metastasizing cells,” explained senior author Sean Morrison, Ph.D., CRI director and chair in pediatric genetics at UT Southwestern Medical Center. “Administration of antioxidants to the mice allowed more of the metastasizing melanoma cells to survive, increasing metastatic disease burden.” he added.

“The idea that antioxidants are good for you has been so strong that there have been clinical trials done in which cancer patients were administered antioxidants,” said Dr. Morrison. “Some of those trials had to be stopped because the patients getting the antioxidants were dying faster. Our data suggest the reason for this: cancer cells benefit more from antioxidants than normal cells do.”

Healthy individuals without cancer may benefit greatly from antioxidants, which may help people reduce the damage caused by high activity oxide molecules generated by normal metabolism. Although the results of this study has not been tested in the crowd, they proposed a possibility: we can treat cancer with the aid of oxidant, but cancer patients should not add a lot of antioxidants in the diet.

“This finding also opens up the possibility that when treating cancer, we should test whether increasing oxidative stress through the use of pro-oxidants would prevent metastasis,” Dr. Morrison noted. “One potential approach is to target the folate pathway that melanoma cells use to survive oxidative stress, which would increase the level of oxidative stress in the cancer cells.”

Reference:

Oxidative stress inhibits distant metastasis by human melanoma cells, Nature.