activity supports cancer cell proliferation under glutamine depletion
Yukiko Takeuchi ² , Yasumune Nakayama b, c , Eiichiro Fukusaki b, Yasuhiro Irino a, d, *
a The Integrated Center for Mass Spectrometry, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe 650-0017, Japan
b Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
c Department of Applied Microbial Technology, Faculty of Biotechnology and Life Science, Sojo University, 4-22-1 Ikeda, Kumamoto 860-0082, Japan
d Division of Evidence-based Laboratory Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe 650-0017, Japan
Cancer cells rapidly consume glutamine as a carbon and nitrogen source to support proliferation, but the cell number continues to increase exponentially after glutamine is nearly depleted from the medium. In
contrast, cell proliferation rates are strongly depressed when cells are cultured in glutamine-free medium. How cancer cells survive in response to nutrient limitation and cellular stress remains poorly understood. In addition, rapid glutamine catabolism yields ammonia, which is a potentially toxic metabolite that is secreted into the extracellular space. Here, we show that ammonia can be utilized for glutamate production, leading to cell proliferation under glutamine-depleted conditions. This proliferation requires glutamate dehydrogenase 2, which synthesizes glutamate from ammonia and a-ketoglutarate and is expressed in MCF7 and T47D cells. Our findings provide insight into how cancer cells survive under glutamine deprivation conditions and thus contribute to elucidating the mechanisms of tumor growth.
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