Madrid scientists find a molecular switch that, when blocked, curbs breast cancer spread in the lab
A team at the Complutense University of Madrid has shown that the protein RAC1 needs a small chemical change to help breast cancer spread. Blocking it drastically reduced lung metastases in experimental models.
Metastasis, when a tumour spreads to other organs, is what makes breast cancer most dangerous. A team at the Complutense University of Madrid has found a way to curb it in the lab.
The discovery
The study, led by Sonia Castillo-Lluva and published in Signal Transduction and Targeted Therapy, focuses on the protein RAC1. It works like a “switch” inside cells, involved in growth, movement and changes of shape. Tumour cells hijack these functions to escape the tumour and invade other tissues.
The team found that RAC1 needs a small chemical modification, called SUMOylation, to drive metastasis. When they blocked it in experimental models, lung metastases dropped drastically, while the original tumour barely changed.
A tailor-made peptide
Blocking RAC1 entirely is not an option, because healthy cells need it too. So the team designed TAT-PRASI, a peptide that enters cells and blocks only the RAC1 functions that depend on that modification. It reduced the ability of breast cancer cells to move and invade, and did the same in organoids (small lab-grown tumours) from patients with HER2+ tumours.
A note of caution
This is laboratory research, in cell lines, experimental models and organoids. It has not been tested in people yet, and more studies are needed before talking about a treatment.
Why it matters
It opens a different route: instead of attacking the whole tumour, specifically stopping its ability to spread, with a more precise effect on cells.
