Antioxidants promote metastasis of cancer cells, researchers found

By John Murphy, MDLinx
Published October 16, 2015

Key Takeaways

Researchers have found that cancer cells benefit even more from antioxidants than normal cells. So, giving cancer patients antioxidants is like feeding the fire of metastasis, according to a study published online October 14, 2015 in Nature.

“We discovered that metastasizing melanoma cells experience very high levels of oxidative stress, which leads to the death of most metastasizing cells,” said corresponding author Sean Morrison, PhD, Director of the Children’s Research Institute and the Mary McDermott Cook Chair in Pediatric Genetics at University of Texas Southwestern Medical Center, in Dallas, Texas. “Administration of antioxidants to the mice allowed more of the metastasizing melanoma cells to survive, increasing metastatic disease burden.”

Investigators have long known that cancer cells are highly inefficient at forming distant metastases. But the reasons for this are not well understood.

In this study, researchers investigated how human melanoma cells would metastasize when transplanted into mice. They observed that melanoma cells in the blood and visceral organs experienced oxidative stress not observed in established tumors. But when the researchers administered antioxidants (N-acetylcysteine)to the mice, the cancer spread more quickly than in mice that didn’t receive antioxidants.

“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,” Dr. Morrison said. “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.”

The researchers realized they could take this research a step further in order to hinder metastasis.

“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,” said Dr. Morrison. “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.”

Healthy people who don’t have cancer may still benefit from antioxidants, which can help reduce damage from highly reactive oxidative molecules generated by normal metabolism.

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