Common antidepressant Zoloft stops cancer cell growth in animal experiments

LEUVEN, Belgium — In advanced forms of cancer, malignant cells can grow and spread at a rapid pace. A new study finds an existing antidepressant which has been proven safe for patients can also cut this growth rate down. Researchers in Belgium say sertraline, commonly sold as Zoloft, has inhibited the growth of cancer cells in laboratory and animal tests.

While other studies have discovered the drug’s anticancer potential too, the new report is revealing what actually makes sertraline so effective at preventing the disease from spreading. Researchers from Katholieke Universiteit Leuven say cancer cells use a different biological process to stimulate their growth. In many forms of the disease, malignant cells produce a large amount of two amino acids called serine and glycine. The study finds cancer cells actually become addicted to these substances and need them to keep growing.

“This mechanism is an interesting target because cancer cells are so dependent on it”, says Professor Kim De Keersmaecker, head of the Laboratory for Disease Mechanisms in Cancer (LDMC), in a university release. “Healthy cells use this mechanism to a lesser extent and also take up serine and glycine from food. This is not sufficient for cancer cells, however, meaning they start producing more. If we can halt this production, we will be able to fight the cancer without affecting healthy cells.”

Hidden cancer fighter in the pharmacy aisle

In a search for drugs that could affect the production of serine and glycine, researchers examined 1,600 different substances on yeast cells.

“There are also yeasts, or molds, which depend on the same mechanism,” research coordinator Dr. Karin Thevissen explains. “Certain yeasts produce these amino acids to protect themselves against antifungals. In addition, you can easily grow yeast cells, allowing you to test many different substances.”

Out of all those compounds, the antidepressant showed the best results at blocking the production of both amino acids. Specifically, the tests reveal the drug is very effective at inhibiting the spread of breast cancer.

“Other studies had already indicated that sertraline has a certain anti-cancer activity, but there was no explanation for this yet”, researchers Shauni Geeraerts and Kim Kampen report. “In this study, we’ve been able to demonstrate that sertraline inhibits the production of serine and glycine, causing decreased growth of cancer cells. We also found that this substance is most effective in combination with other therapeutic agents.”

Sertraline the next tool in the fight against breast cancer?

The Belgium team adds using sertraline along with other cancer therapies on mice significantly slows breast cancer cell growth. Study authors note that leukemia, brain tumors, lung and skin cancer cells also display this biological addiction.

“Now that we’ve been able to identify this mechanism for breast cancer, we can start examining other types of cancer that are also addicted to serine and glycine synthesis,” Prof. De Keersmaecker says. “This is for example the case in T-cell leukemia, but also in certain types of brain, lung and skin cancer. The more tumors we can identify that are sensitive to sertraline, the better the prospects are for helping patients in the future.”

De Keersmaecker cautions that the results have only been confirmed in experimental studies, but the team is optimistic the antidepressant will make it to human trials soon.

“The safety of using sertraline in humans has already been well described, which is a great advantage. That’s why we are also looking for industrial partners to develop this further.”

The study appears in the journal Molecular Cancer Therapeutics.