The drug tamoxifen is a popular treatment option for ER+ breast cancer, but patients can often develop resistance to the drug. New research published in the journal Nature, however, suggests an important discovery for women receiving this therapy. The study, published on April 17 in the journal Nature, focused on how ER+ breast cancer cells are affected by the amino acid leucine, a nutrient that is found abundantly in meats, poultry, and fish.    

The researchers tested the effects of high or low leucine levels in ER+ breast cancer cells, and found that the cells divided less often when they had less leucine. They also found that a certain protein known as SLC7A5, responsible for taking leucine into a cell, interferes with the effects of tamoxifen on cancer cells. On experiments in mice, the researchers used an inhibitor to deactivate the SLC7A5 protein, and found that ER+ tumors in the mice became smaller.     

These results suggest two important implications. Firstly, the findings may point the way to a treatment to overcome tamoxifen resistance, as the SLC7A5 protein may be a promising target. Secondly, switching from a high-leucine, meat-based diet to a reduced-leucine, plant-based diet may be advantageous to women who have been diagnosed with ER+ breast cancer. Further research is currently being conducted in this second area to determine if this diet modification should be recommended.

Read more on the study .