DAMP Laboratory, The Third Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510150, China; Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, Guangzhou Medical University, Guangzhou, Guangdong 510150, China.
Department of Surgery, UT Southwestern Medical Center, Dallas, TX 75390, USA.
Int J Biochem Cell Biol. 2024 Oct;175:106646. doi: 10.1016/j.biocel.2024.106646. Epub 2024 Aug 22.
Alkaliptosis is a type of pH-dependent cell death and plays an emerging role in tumor suppression. However, the key modulation mechanism of alkaliptosis remains largely unknown. In particular, the nucleus, as the centre of genetic and metabolic regulation, is crucial for the regulation of cellular life. It is not known whether nuclear proteins are involved in the regulation of alkaliptosis. Here, we isolated nuclear proteins to perform a proteomics that identified itchy E3 ubiquitin protein ligase (ITCH) as a natural inhibitor of alkaliptosis in human pancreatic ductal adenocarcinoma (PDAC) cells. The downregulation of ITCH protein is associated with the induction of alkaliptosis in three human PDAC cell lines (SW1990, MiaPaCa2, and PANC1). Functionally, increasing ITCH expression reduces JTC801-induced growth inhibition and cell death. In contrast, knocking down ITCH using specific shRNA increases JTC801-induced cell growth inhibition in the short or long term, resulting in increased cell death. Mechanistically, JTC801-induced ITCH inhibition blocks large tumor suppressor kinase 1 (LATS1) ubiquitination, which in turn suppresses Yes1 associated transcriptional regulator (YAP1)-dependent the transcriptional activation of solute carrier family 16 member 1 (SLC16A1), a proton-linked monocarboxylate transporter that inhibits JTC801-induced alkaliptosis. Additionally, decreased expression of ITCH is associated with longer survival times in patients with PDAC. Collectively, our results establish an ITCH-dependent pathway that regulates alkaliptotic sensitivity in PDAC cells and deepen the understanding of alkaliptosis in targeted therapy.
碱中毒是一种依赖 pH 值的细胞死亡方式，在肿瘤抑制中发挥着新兴作用。然而，碱中毒的关键调节机制在很大程度上仍然未知。特别是细胞核作为遗传和代谢调节的中心，对于细胞生命的调节至关重要。目前尚不清楚核蛋白是否参与了碱中毒的调节。在这里，我们分离了核蛋白进行蛋白质组学分析，发现瘙痒 E3 泛素蛋白连接酶（ITCH）是人胰腺导管腺癌（PDAC）细胞中碱中毒的天然抑制剂。ITCH 蛋白的下调与三种人 PDAC 细胞系（SW1990、MiaPaCa2 和 PANC1）中碱中毒的诱导有关。功能上，增加 ITCH 表达可减少 JTC801 诱导的生长抑制和细胞死亡。相反，使用特异性 shRNA 敲低 ITCH 会在短期或长期内增加 JTC801 诱导的细胞生长抑制，导致细胞死亡增加。在机制上，JTC801 诱导的 ITCH 抑制阻止了大肿瘤抑制激酶 1（LATS1）的泛素化，从而抑制了 Yes1 相关转录调节剂（YAP1）依赖的溶质载体家族 16 成员 1（SLC16A1）的转录激活，SLC16A1 是一种质子连接的单羧酸转运蛋白，可抑制 JTC801 诱导的碱中毒。此外，ITCH 的表达降低与 PDAC 患者的生存时间延长有关。总之，我们的研究结果确立了一种依赖 ITCH 的途径，调节 PDAC 细胞的碱中毒敏感性，并加深了对靶向治疗中碱中毒的理解。
