Ming Zhengnan, Luo Tiao, Zou Zizheng, Luo Wensong, Hu Xiyuan, Chen Ling, Zhou Jiang, Liu Xiaohe, Liu Mingquan, Li Jijia, Ma Dayou, Liu Suyou, Luo Zhiyong
Department of Biochemistry and Molecular Biology, Hunan Province Key Laboratory of Basic and Applied Hematology, Hunan Key Laboratory of Animal Models for Human Diseases, School of Life Sciences, Central South University, Changsha 410013, China.
Hunan Key Laboratory of Oral Health Research & Xiangya Stomatological Hospital & Xiangya School of Sto-matology, Central South University, Changsha 410013, China.
Acta Biochim Biophys Sin (Shanghai). 2025 May 30. doi: 10.3724/abbs.2025083.
The urea cycle occurs mainly in the liver and undergoes changes during hepatocarcinogenesis. Argininosuccinate synthase 1 (ASS1) is a key enzyme in the urea cycle and is expressed at low levels in certain cancers. LM2I, a specific activator of ASS1, exhibits significant antitumor activity. However, the antitumor mechanism of LM2I in liver cancer remains unclear. In this study, we find that LM2I is more effective for liver cancer cells with low ASS1 expression. The results of the IP-LC/MS experiments reveal that ASS1 interacts with CAD. The expressions of ASS1 and CAD in liver cancer tissues and cells are negatively correlated. LM2I promotes the ubiquitination of CAD protein through ASS1. LM2I inhibits the proliferation of liver cancer cells and . However, its efficacy is weak in liver cancer cells stably overexpressing CAD. The H&E staining results reveal that LM2I has no toxicity in mice. In terms of metabolism, LM2I increases the urea content and decreases the pyrimidine content in liver cancer cells. Overexpression of CAD can reduce the inhibitory effect of LM2I on pyrimidine. Pyrimidine supplementation facilitates the proliferation of liver cancer cells, particularly when they are treated with LM2I. In summary, ASS1 interacts with CAD, and LM2I enhances CAD degradation through the activation of ASS1, consequently inhibiting pyrimidine synthesis and the progression of liver cancer.
尿素循环主要发生在肝脏中，并在肝癌发生过程中发生变化。精氨琥珀酸合酶1（ASS1）是尿素循环中的关键酶，在某些癌症中表达水平较低。LM2I是ASS1的特异性激活剂，具有显著的抗肿瘤活性。然而，LM2I在肝癌中的抗肿瘤机制仍不清楚。在本研究中，我们发现LM2I对ASS1低表达的肝癌细胞更有效。免疫沉淀-液相色谱/质谱实验结果表明，ASS1与CAD相互作用。肝癌组织和细胞中ASS1和CAD的表达呈负相关。LM2I通过ASS1促进CAD蛋白的泛素化。LM2I抑制肝癌细胞的增殖， 。然而，其在稳定过表达CAD的肝癌细胞中的疗效较弱。苏木精-伊红染色结果表明，LM2I对小鼠无毒。在代谢方面，LM2I增加肝癌细胞中的尿素含量并降低嘧啶含量。CAD的过表达可降低LM2I对嘧啶的抑制作用。补充嘧啶促进肝癌细胞的增殖，尤其是在用LM2I处理时。总之，ASS1与CAD相互作用，LM2I通过激活ASS1增强CAD降解，从而抑制嘧啶合成和肝癌进展。
