1. Academic Validation
  2. The protection of UCK2 protein stability by GART maintains pyrimidine salvage synthesis for HCC growth under glucose limitation

The protection of UCK2 protein stability by GART maintains pyrimidine salvage synthesis for HCC growth under glucose limitation

  • Oncogene. 2025 Jan 26. doi: 10.1038/s41388-025-03274-7.
Nannan Sha # 1 Bei Zhou # 1 Guofang Hou 1 Zhifeng Xi 1 Wang Wang 1 Man Yan 1 Jing He 1 Yue Zhou 1 Qiang Xia 2 Yuhui Jiang 3 Qin Zhao 4
Affiliations

Affiliations

  • 1 Department of Liver Surgery and Shanghai Cancer Institute, State Key Laboratory of Systems Medicine for Cancer, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
  • 2 Department of Liver Surgery and Shanghai Cancer Institute, State Key Laboratory of Systems Medicine for Cancer, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. xiaqiang@shsmu.edu.cn.
  • 3 Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, Shanghai, China. yuhuijiang@ecust.edu.cn.
  • 4 Department of Liver Surgery and Shanghai Cancer Institute, State Key Laboratory of Systems Medicine for Cancer, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. zhaoqin@renji.com.
  • # Contributed equally.
Abstract

Overexpression of uridine-cytidine kinase 2 (UCK2), a key Enzyme in the pyrimidine salvage pathway, is implicated in human Cancer development, while its regulation under nutrient stress remains to be investigated. Here, we show that under glucose limitation, AMPK phosphorylates glycinamide ribonucleotide formyltransferase (GART) at Ser440, and this modification facilitates its interaction with UCK2. Through its binding to UCK2, GART generates tetrahydrofolate (THF) and thus inhibits the activity of integrin-linked kinase associated Phosphatase (ILKAP) for removing AKT1-mediated UCK2-Ser254 phosphorylation under glucose limitation, in which dephosphorylation of UCK2-Ser254 tends to cause Trim21-mediated UCK2 polyubiquitination and degradation. In this way, both UCK2 binding ability and THF producing catalytic activity of GART protect protein stability of UCK2 and pyrimidine salvage synthesis, and sustain tumor cell growth under glucose limitation. In addition, UCK2-Ser254 phosphorylation level displays a positive relationship with GART-Ser440 phosphorylation level and its enhancement is correlated with poor prognosis of human hepatocellular carcinoma (HCC) patients. These findings reveal a non-canonical role of GART in regulating pyrimidine salvage synthesis under nutrient stress, and raise the potential for alternative treatments in targeting pyrimidine salvage-dependent tumor growth.

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