In a new study in mice, researchers have had success in encouraging human breast cancer cells to turn into harmless fat cells.

The study, which was published in January 2019, explains how scientists were able to manipulate cancer cells through the process of epithelial-mesenchymal transition (EMT), which is when epithelial cells gain invasive properties to become mesenchymal stem cells that can then differentiate into a variety of cell types.

What does this look like? As Jacinta Bowler explains in Science Alert, “When you cut your finger, or when a fetus grows organs, the epithelium cells begin to look less like themselves, and more ‘fluid’—changing into a type of stem cell called a ‘mesenchyme’ and then reforming into whatever cells the body needs.”

The researchers took mice implanted with human breast cancer and treated them with both a diabetic drug called “rosiglitazone” and a cancer treatment drug called “trametinib,” and something interesting happened.

“Thanks to these drugs, when cancer cells used one of the above-mentioned transition pathways, instead of spreading they changed from cancer into fat cells—a process called adipogenesis,” Bowler writes.

“The models used in this study have allowed the evaluation of disseminating cancer cell adipogenesis in the immediate tumour surroundings,” the research team wrote in their paper. “The results indicate that in a patient-relevant setting combined therapy with rosiglitazone and trametinib specifically targets cancer cells with increased plasticity and induces their adipogenesis.”

Not every cancer cell changed into a fat cell, but the ones that underwent adipogenesis didn’t change back.

“The breast cancer cells that underwent an EMT not only differentiated into fat cells, but also completely stopped proliferating,” said Gerhard Christofori, one of the authors of the study and a biochemist at the University of Basel.

“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.”

Both rosiglitazone and trametinib are already FDA-approved drugs, so researchers are hopeful that it will be easy to start clinical trials for people.

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