In mice, scientists turned breast cancer cells into fat

Researchers at the University of Basel combined a MEK-inhibiting cancer drug with rosiglitazone, a medication normally used to treat type 2 diabetes, and gave the combination to mice with aggressive, spreading breast tumors.

The drug combination forced the invasive cancer cells to convert into mature, non-dividing fat cells, a process called adipocyte transdifferentiation. Once trapped in that fat-cell state, the former cancer cells stopped multiplying and stopped invading nearby tissue, sharply reducing the spread of tumors to the lungs in the treated mice.

This worked specifically on cells that had already shifted into the invasive, mesenchymal-like state associated with metastasis, not on tumors generally, so the approach targets a specific vulnerability in the most dangerous cells rather than the tumor as a whole. The work was done in mice and cultured human cancer cells, and rosiglitazone's own cardiovascular risks mean translating the combination into people will require a careful safety case.

Some tumors were talked into retiring.