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A new study published in the journal Nature shows that asparagine, a protein building block that takes its name from asparagus, promotes the spread of breast cancer in mice. The study by cancer experts from Britain, Canada and the U.S. investigated whether limiting the levels of asparagine in mice could reduce tumor metastasis. (3/2/18)
Identifying new targets that reduce the ability of breast cancer cells to spread and become metastatic.
Breast cancer becomes deadly when it metastasizes—cancer cells leave the breast, enter the blood stream and then invade a secondary site such the brain, lungs or other organs. This study suggests that reducing the amount of the amino acid asparagine may be one way to decrease the likelihood of breast cancer becoming
In mice that were bred to develop breast cancer:
“When the availability of asparagine was reduced, we saw little impact on the primary tumor in the breast [in mice], but tumor cells had reduced capacity for metastases in other parts of the body," said Greg Hannon, lead study author and Cambridge University cancer researcher.
Breast cancer that stays confined to the breast is not deadly. But it is more difficult to treat and can become fatal if it metastasizes—if cancer cells spread beyond the tumor and into other organs in the body. These preliminary study results imply that reducing bodily amounts of asparagine is one way to decrease the risk of breast cancer
metastasis. This result, however, needs to be confirmed by other studies. In addition, it is important to remember that animal models of breast cancer do not always mimic the disease in humans.
Even if future guidelines were to support a reduction of asparagine to decrease the risk of breast cancer
metastasis, it is virtually impossible to eliminate the substance from your diet. Foods rich in asparagine include not only asparagus, but also dairy, beef, poultry, eggs, fish, seafood, potatoes, legumes, nuts, seeds, soy and whole grains. Experts agree that you should not drastically change your diet in an attempt to reduce the amount of asparagine you consume. Asparagine is found in all protein rich foods-many of which are considered part of a healthy diet. In addition, your body naturally makes asparagine. If you are concerned about how your diet will affect your outcome consider discussing this with your doctor or a nutritionist.
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Preventing or eliminating metastasis is an important goal of breast cancer treatment. Mouse models of breast cancer are often used to better understand how breast cancers metastasize and to identify potential targets for treatment that can reduce or eliminate the
metastatic potential of breast cancer cells.
Asparagine is an amino acid that is a building block for proteins. Found in many foods, it is also made in the body by a cellular enzyme called asparagine synthetase. This study evaluated the effect of asparagine, either in the diet or produced by the naturally occurring enzyme asparagine synthetase, on breast cancer
Which molecules can cause breast cancer cells to metastasize?
This study used mice models of
metastatic breast cancer. In addition, researchers looked at levels of asparagine synthetase in breast cancer patients and in a small sample of matched breast tumor and lung metastasis samples.
Initially the study authors used sophisticated in vitro (test tube) techniques to identify molecules that may cause
metastasis. Among the top candidates, asparagine synthetase appeared to play a critical role. The researchers then conducted multiple areas of related mouse study:
Interestingly, when the study authors reviewed records of breast cancer patients (gene expression data from 2 data sets as well as a small number of matched breast tumors and lung metastases), they found that breast tumors with the highest levels of asparagine synthetase were most likely to metastasize, especially to the lymph nodes, brain, liver, and lungs.
It is important to remember that cancer therapies that work well in rodents don’t always translate to humans. While it is possible that dietary intake of asparagine may influence
metastatic potential of breast cancer in humans, this hypothesis needs to be validated in human studies.
Asparagine is a non-essential amino acid that our bodies naturally synthesize. This new study suggests that decreasing levels of asparagine in mice reduces
metastasis. If after further study, reduction of asparagine levels proves to reduce the metastatic potential of human breast cancer, other methods to reduce cellular availability of asparagine may need to be developed, because regulating dietary levels of asparagine would be extremely difficult, if not impossible.
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Knott, Simon RV, Wegenblast E, et al. “Asparagine bioavailability governs metastasis in a model of breast cancer.” Nature. February 15, 2018; Vol. 554:378–381.
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