Brain cancer is one of the deadliest cancers out there, and glioblastoma (GBM) is the most common and most dangerous form of the disease. Treating this type of tumor is hard and preventing them is nearly impossible — the cause of most cases is unclear. Now researchers at The Ohio State University Comprehensive Cancer Center have discovered a possible new way to slow GBM progression and perhaps even prevent it.

The study suggests that GBMs metabolize the essential amino acids methionine and tryptophan (yes, the stuff in turkey) in an unusual way that helps them grow and survive. The tumors lack certain enzymes, which lets them metabolize methionine in a way that leads to oncogenes — mutated cells with the potential to become cancerous — and change tryptophan metabolism in a way that shields GBM from detection by immune cells.

“Our findings suggest that restricting dietary intake of methionine and tryptophan might help slow tumor progression and improve treatment outcomes,” said Dr. Lamalakannan Palanichamy, a researcher at the cancer center and first author of the study.

Principal investigator and study leader Dr. Arnab Chakravarti added that the team needs to better understand exactly how these metabolites work for GBMs to find new therapeutic targets in the tumors.

“For example, restoring the lost enzymes in the two metabolic pathways might slow tumor progression and reduce aggressiveness by inactivating oncogenic kinases and activating immune responses,” said Chakravarti, who is also chair and professor of radiation oncology and co-director of the brain tumor program at the center.

Chakravarti also pointed out that since GBM cells suck up methionine much faster than normal cells, doctors could follow the amino acid with  positron emission tomography to map the tumors more accurately. This would allow for more precise surgical removal and better planning for radiation therapy. Currently the technique is only an experimental method.

Proteins are made up of amino acids, and both methionine and tryptophan are essential, meaning that a person’s diet must provide them because cells cannot make them. Lack of an essential amino acid can lead to serious health consequences and death. Many foods are rich in methionine and tryptophan, including cheese, lamb, beef, turkey, eggs, soybeans, and nuts.

Source; Palanichamy K, Thirumoorthy K, Kanji S, Gordon N, Singh R, Jacob R, et al. Methionine and Kynurenine Activate Oncogenic Kinases in Glioblastoma, and Methionine Deprivation Compromises Proliferation. Clinical Cancer Research. 2016.