Researchers at the University of Basel in Switzerland have found a way to transform breast cancer cells into fat cells by exploiting a pivotal moment in their life-cycle. At least, they have in mice. 

The success of the technique, published in the journal Cancer Cell, hinges on a process called epithelial-mesenchymal transition (EMT).

In response to cues in their microenvironment, epithelial cells reach a state of high plasticity, enabling them to convert into a different type of cell. At this stage, EMT, the cell resembles something close to a stem cell.

The process is essential to various physiological mechanisms, including embryonic development and wound healing. But, unfortunately, it also has some less benign results. Cancer cells use EMT and its reverse process (mesenchymal-epithelial transition, or MET) to travel from one part of the body to another. This allows cancer to spread to different organs and different tissues – hence, primary and secondary cancer.

It does, however, also give scientists an opportunity to target the cancer in a vulnerable state. The idea here is that if you are to target the cancerous cells in this state of high plasticity before they reach MET, it may be possible to transform them to a less-malign state and, therefore, prevent the development of a secondary cancer.

To see if their suspicions were correct, the team at Basel used mice given human breast cancer cells. The mice were given two doses of drugs already approved by the US Food and Drug Administration (FDA), one a cancer inhibitor (trametinib) and the second an anti-diabetic drug (rosiglitazone). 

The results have been extremely promising. Not only were they able to prevent the cancer from spreading to other parts of the body (metastasizing) but they were also able to quell the growth of the primary tumor by preventing cancer cells within that tumor from multiplying. Aggressive cancer cells that detached from the primary tumor to find new ground were instead turned into fat cells, putting them in a state where they were unable to do the body much harm.

"The breast cancer cells that underwent an EMT not only differentiated into fat cells, but also completely stopped proliferating," first author Gerhard Christofori, a professor of biochemistry at the University of Basel, said in a statement. "As far as we can tell from long-term culture experiments, the cancer cells-turned-fat cells remain fat cells and do not revert back to breast cancer cells."

Of course, right now, we only know this treatment works in mice. Its effectiveness in humans is still unknown. It is also worth pointing out that it does not transform all cancer cells, only those undergoing EMT during metastasization. Which means even if and when it does become an option for patients, it will most likely need to be used in conjunction with chemo, not instead of. 

Next, the researchers hope to look at how this technique can be used with existing chemotherapies and whether it can be adopted for other cancers.