A protein building block found in asparagus and other foods may hold a key to preventing the spread of an often-deadly type of breast cancer, according to Cedars-Sinai scientists in a new study published Wednesday.
Investigators determined that by limiting an amino acid called asparagine in laboratory mice with triple-negative breast cancer, they could reduce the ability of the cancer to travel to distant sites in the body. Among other techniques, the team used dietary restrictions to limit asparagine. Foods rich in asparagine include dairy, whey, beef, poultry, eggs, fish, seafood, asparagus, potatoes, legumes, nuts, seeds, soy and whole grains.
Foods low in asparagine include most fruits and vegetables, according to the multi-center study published in the medical journal Nature.
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"Our study adds to a growing body of evidence that suggests diet can influence the course of the disease,'' said Dr. Simon Knott, associate director of the Center for Bioinformatics and Functional Genomics at Cedars-Sinai and one of two first authors of the study.
The research was conducted at more than a dozen institutions.
If further research confirms the findings in human cells, limiting the amount of asparagine cancer patients ingest could be a potential strategy to augment existing therapies and to prevent the spread of breast cancer, Knott said.
The researchers studied triple-negative breast cancer cells, which grow and spread faster than most other types of cancer cells. It is called triple negative because it lacks receptors for the hormones estrogen and progesterone and makes little of a protein called HER2. As a result, it resists common treatments that target these factors and has a higher-than-average mortality rate.
Research from past studies found that most tumor cells remain in the primary breast site, but a subset of cells leaves the breast and enters the bloodstream. Those cells colonize in the lungs, brain and liver, where they proliferate. The study team wanted to understand the particular traits of the tumor cells circulating in the blood and in the sites where the cancer has spread.
The researchers discovered that the appearance of asparagine synthetase -- the enzyme cells used to make asparagine -- in a primary tumor was strongly associated with later cancer spread.
Studying the effects of asparagine also could alter treatments for other types of cancer, investigators say.
"This study may have implications not only for breast cancer, but for many metastatic cancers," said Dr. Ravi Thadhani, vice dean of Research and Graduate Research Education at Cedars-Sinai.