Lab mouse
Cutting certain amino acids from the diet slows tumor growth and prolongs survival in mouse models of malignancy, according to research published in Nature.
Researchers found that removing 2 non-essential amino acids—serine and glycine (SG)—from the diet of mice slowed the development of lymphoma and intestinal cancer.
The SG-free diet also made lymphoma more susceptible to reactive oxygen species (ROS).
As chemotherapy and radiotherapy boost levels of ROS, the researchers believe an SG-free diet could make conventional cancer treatments more effective.
“Our findings suggest that restricting specific amino acids through a controlled diet plan could be an additional part of treatment for some cancer patients in future, helping to make other treatments more effective,” said study author Oliver Maddocks, PhD, of the University of Glasgow in the UK.
He and his colleagues tested the SG-free diet in mouse models of lymphoma (Eμ-Myc) and observed decreased tumor volume and lymphoma cell numbers as well as a significant improvement in survival compared to controls.
The median survival (from the time of diet change at day 60) was 192 days for mice on the SG-free diet and 59 days for mice on the control diet (P=0.0367).
To test whether increasing ROS could enhance the anticancer effects of the SG-free diet, the researchers crossed Eμ-Myc mice with mice that don’t express Tigar, a protein that can support tumor development by limiting ROS.
The researchers found that Tigar -/- mice on the SG-free diet had significantly better survival than Tigar -/- mice on the control diet (P=0.0451).
The median survival was 50.5 days for Tigar +/+ mice on the control diet, 80 days for Tigar +/+ mice on the SG-free diet, 107 days for Tigar -/- mice on the control diet, and 226 days for Tigar -/- mice on the SG-free diet.
The researchers also found the SG-free diet was less effective in cancers with an activated Kras gene (such as prostate cancer) because the faulty gene boosted the cancer cells’ ability to make their own serine and glycine. The team said this could help in selecting which tumors could be best targeted by diet therapy.
“This is a really interesting look at how cutting off the supply of nutrients essential to cancer cell growth and division could help restrain tumors,” said Emma Smith, PhD, of Cancer Research UK, which funded this study.
“The next steps are clinical trials in people to see if giving a specialized diet that lacks these amino acids is safe and helps slow tumor growth as seen in mice. We’d also need to work out which patients are most likely to benefit, depending on the characteristics of their cancer.”
