Resveratrol and Radiation

Resveratrol is a
phytochemical found in high levels in grape skins. Not only is resveratrol an
antioxidant, it has some cancer preventive properties as well. In addition,
there’s increasing interest in its potential use in cancer treatment. Since
it’s an antioxidant, and since many chemotherapies as well as radiation act by
producing free radicals that can damage cellular DNA, researchers and
clinicians have been cautious about combining resveratrol with conventional
treatment. Dr. Block and his research team have reviewed the clinical
literature on antioxidants and chemotherapy and feel this concern is misplaced.
Randomized clinical trials in which antioxidants were given with chemotherapy
did not show any reduction in anticancer effects compared to chemotherapy given
with no antioxidants. In addition, a new paper published in the Journal of
Surgical Research recently suggested that concern about combining resveratrol
with radiation therapy is similarly misplaced.

Radiation is often used
when treating melanoma, both when it is localized and also for the treatment of
metastatic melanoma. Researchers at the University of Missouri have already
shown that resveratrol enhanced the effect of radiation on prostate cancer
cells. They decided to see if resveratrol would boost the effect of radiation
on the more resistant melanoma cells. Resveratrol is already known to kill
cancer cells, and indeed, when cancer cells were exposed to resveratrol alone,
44% of the cancer cells died. When resveratrol and radiation were both used on
melanoma cells, 65% of them died— more than is usually expected with radiation
to this relatively resistant cell type. 

The Missouri researchers
investigated this process at a molecular level as well. Two of the ways that
radiation and resveratrol could fight cancer are to slow cancer cell growth or
proliferation (i.e., the rapid cell division that cancer cells undergo). Cancer
cells could also be killed through cellular suicide or apoptosis. It turns out
that the combination of resveratrol and radiation both slowed cancer cell
proliferation and caused apoptosis. This double whammy suggests that combining
resveratrol and radiation could be very helpful for tumor control. The
researchers point out, though, that we need to do clinical trials to find out
if this actually works, since it is not yet clear whether resveratrol can be
transported effectively in the body to reach the melanoma tumors that are being
treated.

Thus, this potent
botanical antioxidant paradoxically increases the activity of a free-radical
generating therapy. This may seem strange, but as we learn more about how
antioxidants work, especially in the context of cancer, this kind of
relationship is becoming more plausible. Researchers in India published a paper
in April of 2012 in which they showed that resveratrol interacts with both
copper and acidity to produce DNA damage and apoptosis. Cancer cells contain
more copper than normal cells, and tumors are very acidic. Giving resveratrol
to copper-bearing, acidic cancer cells has a very different effect from giving
it to lower-copper, normal-acidity normal cells, which are not killed by
resveratrol. Other work by these researchers and their colleagues have shown
that the interaction of natural antioxidants like resveratrol with copper
causes the production of—surprise!—free radicals, which can damage DNA and
trigger apoptosis. While we don’t know exactly what is happening when
resveratrol interacts with radiation, it’s tempting to think that the free
radicals produced by interaction with copper add to the free radicals from
radiation therapy, thus producing a synergistic anticancer effect on melanoma
cells. A similar mechanism may be at work in the interactions of antioxidants
and chemotherapy found by Dr. Block and his research team in their literature
review. With these new data, we continue to support the use of natural
antioxidants with conventional cancer treatment.

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