Ultrasound-controlled bacteria effectively destroy cancerous tumors

While bursts of ultrasound had previously eliminated cancerous cells by heating them, the latter also destroyed the surrounding healthy cells. American researchers have recently found a safe way to exploit them by associating them with bacteria.

Using microorganisms to fight cancer

Bacteria play a major role in maintaining our health, especially those that naturally colonize our intestines, but are also known to cause life-threatening infections and illnesses. Although the idea of ​​using these microorganisms to fight cancer may seem far-fetched, it is very far from new.

In the 19th century, the American surgeon William Coley was the first to notice the anti-cancer effect of bacterial colonies located near tumours. Seeking to take advantage of this bizarre relationship between certain bacteria and cancer cells, researchers have since come up with all sorts of therapies, including delivering chemotherapy drugs directly to cancer cells via bacteria.

Such a holistic approach also harms healthy cells, in work published in the journal NatureCommunications, Mikhail Shapiro and his colleagues from Caltech have devised a clever way to take advantage of the anti-cancer properties of bacteria, involving genetically modifying Escherichia coli so that it can withstand temperature peaks induced by ultrasound bursts.

When the bacteria’s temperature reaches around 42-43°C, a pair of genes express cancer-fighting molecules similar to immune system antibodies, which deactivate proteins that promote cancer cell proliferation. Since the human body temperature is around 37°C, the modified strains only begin to release their anti-tumor nanobodies when exposed to certain levels of ultrasound.

First promising results

In an experiment, immunocompromised mice with non-Hodgkin’s lymphoma were infected withE.coli modified, then bursts of ultrasound were focused on the tumor sites. The researchers noticed that the tumors had stopped growing and even shrunk within two weeks.

” Focused ultrasound allowed us to activate therapy specifically inside tumors “, highlighted Mohamad Abedi, co-author of the study. “ This is important because these powerful chemotherapeutic substances, which are so useful in the treatment of cancers, could also cause significant side effects in the organs where our bacterial agents are likely to be present.. »

If the main objective obviously remains the holding of clinical trials in order to examine the effects of the treatment on our organism, the next step will consist in improving the marking of the bacteria in order to be able to locate them in real time and to use the ultrasounds of more targeted way. According to the team, such an approach could also target other diseases such as cystic fibrosis.