New Study Reveals Breast Cancer Cells Recycle Their Own Ammonia Waste as Fuel

Source: Harvard Medical School

Summary: A new study finds that breast cancer cells recycle ammonia and use it as a source of nitrogen to fuel tumor growth.

During cell metabolic processes a waste byproduct, ammonia is released. The breast cancer cells use this ammonia as a source of nitrogen to cause the growth of the tumor. Researchers from Harvard Medical School found that ammonia accelerates the proliferation of breast cancer cells in the culture and when ammonia metabolism is suppressed, tumor growth is stunted in mice. Fast growing cells, specifically cancer cells, feed on nutrients voraciously and release lot excess metabolic waste. One of the byproducts is ammonia and is transported in blood vessels to the liver for its conversion in to less toxic substance and from there get excreted out of the body as urea.The findings were published in the journal Science.

Breast cancer cells recycle their own ammonia waste as fuel

breast tumor and its local environment. Tumor cells display in cyan, macrophages in red, collagen fibers in green. Credit: National Cancer Institute

However, tumors have few blood vessels and give room to ammonia to get accumulated in the tumor’s local environment in high concentrations which would be toxic to many cells. To study how tumors cope with high levels of ammonia researchers used a technique to label the nitrogen on glutamine. By tracing this marked ammonia they analyzed more than 200 various cellular metabolites in breast cancer cells and in human tumors transplanted into mice. These insights help to know the biological role of ammonia in cancer and also helps to design a new therapeutic strategy to slow the tumor growth.

Senior study author, Marcia Haigis said, “Classically, ammonia was thought to be metabolic waste that must be cleared due to its high toxicity”, “We found that not only was ammonia not toxic for breast cancer cells, it could be used to feed tumors by serving as a source for the building blocks that tumors need to grow.”

More Information: Jessica B.Spinelli et al, “Metabolic recycling of ammonia via glutamate dehydrogenase supports breast cancer biomass”, Science (2017). DOI: 10.1126/science.aam9305


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