Common depression drugs may help treat cancer, study finds

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A class of drug called monoamine oxidase inhibitors is commonly prescribed to treat depression; the medications work by boosting levels of serotonin, the brain’s “happiness hormone.”

In a new study from UCLA, researchers found that those drugs, commonly known as MAOIs, might have another health benefit: helping the immune system attack cancer.

Recent advances in understanding how the human immune system naturally seeks out and destroys cancer cells, as well as how tumors try to evade that response, has led to new cancer immunotherapies — drugs that boost the immune system’s activity to try to fight cancer.

In the study, the team compared immune cells from skin cancer (melanoma) tumors in mice to immune cells from cancer-free animals.

They found that mice treated with the drug MAOIs were better at controlling the growth of melanoma and colon tumors. They also found that normal mice became more capable of fighting those cancers when treated with MAOIs.

Digging into the effects of MAO-A on the immune system, the researchers discovered that T cells — the immune cells that target cancer cells for destruction — have a lower ability to fight cancer when they recognize tumors.

The scientists report that MAOIs help T cells overcome the immune checkpoint and more effectively fight cancer.

But the drugs also have a second role in the immune system.

The researchers discovered that MAOIs block immunosuppressive tumor-associated macrophages, effectively breaking down one line of defense that tumors have against the human immune system.

It turns out that MAOIs seem to both directly help T cells do their job, and stop tumor-associated macrophages from putting the brakes on T cells.

The team says that MAOIs may work well in concert with a type of cancer immunotherapies called immune checkpoint blockade therapies, most of which work by targeting immune checkpoint molecules on the surface of immune cells.

Studies in mice showed that any of three existing MAOIs — phenelzine, clorgyline or mocolobemide — either on their own or in combination with a form of immune checkpoint blockade therapy, could stop or slow the growth of colon cancer and melanoma.

The researchers are already planning additional studies to test the effectiveness of MAOIs in boosting human immune cells’ response to various cancers.

If you care about depression and your health, please read studies about why depression drugs may not work for some patients and findings of eating fruits and vegetables may help reduce the risk of depression.

For more information about depression prevention and treatment, please see recent studies about common daily nutrient could protect you from depression and results showing that depression symptoms could be signs for cognitive decline in some people.

The study findings are published in Science Immunology and Nature Communications. One author of the study is Lili Yang.

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