Institute of Digestive Disease of Guangzhou Medical University, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, 511500, Qingyuan, Guangdong, China.
Affiliated Cancer Hospital & institute of Guangzhou Medical University,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, 511436, Guangzhou, Guangdong, China.
J Exp Clin Cancer Res. 2021 Jun 21;40(1):201. doi: 10.1186/s13046-021-02008-3.
Hepatocellular carcinoma (HCC) remains a medical challenge due to its high proliferation and metastasis. Although deubiquitinating enzymes (DUBs) play a key role in regulating protein degradation, their pathological roles in HCC have not been fully elucidated.
By using biomass spectrometry, co-immunoprecipitation, western blotting and immunofluorescence assays, we identify ribosomal protein S16 (RPS16) as a key substrate of ubiquitin-specific peptidase 1 (USP1). The role of USP1-RPS16 axis in the progression of HCC was evaluated in cell cultures, in xenograft mouse models, and in clinical observations.
We show that USP1 interacts with RPS16. The depletion of USP1 increases the level of K48-linked ubiquitinated-RPS16, leading to proteasome-dependent RPS16 degradation. In contrast, overexpression of USP1-WT instead of USP1-C90A (DUB inactivation mutant) reduces the level of K48-linked ubiquitinated RPS16, thereby stabilizing RPS16. Consequently, USP1 depletion mimics RPS16 deficiency with respect to the inhibition of growth and metastasis, whereas transfection-enforced re-expression of RPS16 restores oncogenic-like activity in USP1-deficient HCC cells. Importantly, the high expression of USP1 and RPS16 in liver tissue is a prognostic factor for poor survival of HCC patients.
These findings reveal a previously unrecognized role for the activation of USP1-RPS16 pathway in driving HCC, which may be further developed as a novel strategy for cancer treatment.
肝细胞癌（HCC）仍然是一个医学挑战，因为它具有高增殖和转移的特性。虽然去泛素化酶（DUBs）在调节蛋白质降解中起着关键作用，但它们在 HCC 中的病理作用尚未完全阐明。
通过使用生物质谱、共免疫沉淀、western blot 和免疫荧光分析，我们确定核糖体蛋白 S16（RPS16）是泛素特异性肽酶 1（USP1）的关键底物。在细胞培养物、异种移植小鼠模型和临床观察中，评估了 USP1-RPS16 轴在 HCC 进展中的作用。
我们表明 USP1 与 RPS16 相互作用。USP1 的耗竭会增加 K48 连接的泛素化-RPS16 的水平，导致蛋白酶体依赖性 RPS16 降解。相比之下，过表达 USP1-WT（而不是 USP1-C90A（DUB 失活突变体））会降低 K48 连接的泛素化 RPS16 的水平，从而稳定 RPS16。因此，USP1 耗竭在抑制生长和转移方面模拟了 RPS16 的缺乏，而转染强制表达 RPS16 则恢复了 USP1 缺陷 HCC 细胞中的致癌样活性。重要的是，USP1 和 RPS16 在肝组织中的高表达是 HCC 患者预后不良的一个预后因素。
这些发现揭示了 USP1-RPS16 通路的激活在驱动 HCC 中的一个以前未被认识的作用，这可能进一步被开发为癌症治疗的新策略。
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