A diet that starves triple-negative breast cancer cells of an essential nutrient primes the cancer cells to be more easily killed by a targeted antibody treatment, according to new research published in the journal Clinical Cancer Research. The study lays the foundation for a clinical trial to see if a low-methionine diet will help improve outcomes in women with "triple-negative" breast cancer.
Methionine is an essential amino acid that is present in low concentrations in some vegan diets. Patients with triple-negative breast cancer have limited treatment options because their tumor cells lack the three receptors - estrogen, progesterone and human epidermal growth factor receptor 2 (HER-2) - commonly targeted in hormone or chemotherapy.
Scientists have known for decades that methionine deficiency can block the growth of many types of cancer, but the underlying mechanisms have puzzled researchers. Specifically, the researchers showed that when triple-negative breast cancer cells were deprived of methionine - an essential nutrient abundant in meat, fish, some legumes and nuts, but low in fruits and vegetables - the stressed cancer cells responded by increasing the amount of a receptor on the cell's surface called TRAIL-R2.
This resulted in the breast cancer cells becoming very sensitive to an antibody that binds to TRAIL-R2 on the surface of the cancer cells and triggers them to die.
The researchers fed mice with triple-negative breast tumors a diet lacking methionine and treated them with an antibody that binds to the TRAIL-R2 receptor. Mice, like humans, can tolerate a methionine-free diet for a short period of time. The combination of diet and antibody was more effective at shrinking the breast tumors and preventing metastasis to the lungs than either treatment alone.
The team believes that their laboratory studies may pave the way for a clinical trial in breast cancer patients to examine the effectiveness of a low-methionine diet in combination with a TRAIL-R2 monoclonal antibody. When used alone, TRAIL-R2 antibodies have not been effective in patients with metastatic solid tumors.
Based on material originally posted by University of Wisconsin-Madison.