Fang Ronghuan, Jia Zhigang, Xin Yuhang, Zhao Kai, Qin Wei, Lu Haoran, Zhou Yi, Yang Yongsheng, Fang He
Department of Hepatobiliary Pancreatic Surgery, The Second Hospital of Jilin University, Changchun, China.
Jilin Engineering Laboratory for Translational Medicine of Hepatobiliary and Pancreatic Diseases, Changchun, China.
Cell Death Discov. 2025 Jan 10;11(1):3. doi: 10.1038/s41420-024-02282-y.
Hepatocellular carcinoma (HCC) is among the most malignant tumors and seriously threatens human health worldwide, and its incidence rate is increasing annually. USP15 is a member of the ubiquitination-specific protease (USP) family, which can regulate protein ubiquitination, thereby affecting their stability, and is dysregulated in many cancers, but its expression and regulatory mechanism in HCC are unclear. The aims of this study were to explore the role and mechanism of USP15 in regulating HCC cell stemness, proliferation, and lenvatinib resistance. Immunohistochemistry and high-throughput sequencing analyses of tumor and adjacent normal tissue samples from 52 patients with HCC were conducted. Functional analyses of immortalized human liver and HCC cell lines were conducted, including quantitative real-time PCR; western blot; plasmid, lentivirus, and siRNA transfection; co-immunoprecipitation; mass spectrometry; MeRIP-qPCR; and ubiquitination, cell growth, colony formation, and spheroid formation assays. HCC tumor growth was also assessed using cell transplantation in nude mice. We found that USP15 is upregulated in HCC and affects patient prognosis. Our results demonstrated that USP15 can increase LGALS3 stability in HCC through deubiquitination modification, and affect the stemness, proliferation, and lenvatinib resistance of HCC cells by activating the AKT/mTOR pathway. USP15 expression levels were positively correlated with HCC cell stemness, proliferation, and lenvatinib resistance. In addition, methyltransferase-like protein 3 (Mettl3) N6-methyladenosine (m6A) modified USP15 to upregulate its levels by increasing its mRNA stability. These findings provide a theoretical basis for the potential discovery of new HCC oncogenes, as well as the identification of effective targets and development of novel anti-HCC drugs and clinical applications.
肝细胞癌（HCC）是最恶性的肿瘤之一，严重威胁着全球人类健康，且其发病率逐年上升。USP15是泛素化特异性蛋白酶（USP）家族的成员，可调节蛋白质泛素化，从而影响其稳定性，在许多癌症中表达失调，但其在HCC中的表达及调控机制尚不清楚。本研究旨在探讨USP15在调节HCC细胞干性、增殖及仑伐替尼耐药性中的作用及机制。对52例HCC患者的肿瘤及癌旁正常组织样本进行了免疫组织化学和高通量测序分析。对永生化人肝和HCC细胞系进行了功能分析，包括定量实时PCR、蛋白质印迹、质粒、慢病毒和小干扰RNA转染、免疫共沉淀、质谱分析、甲基化RNA免疫沉淀定量PCR以及泛素化、细胞生长、集落形成和球体形成试验。还通过裸鼠细胞移植评估了HCC肿瘤生长情况。我们发现USP15在HCC中上调并影响患者预后。我们的结果表明，USP15可通过去泛素化修饰增加HCC中LGALS3的稳定性，并通过激活AKT/mTOR途径影响HCC细胞的干性、增殖及仑伐替尼耐药性。USP15表达水平与HCC细胞干性、增殖及仑伐替尼耐药性呈正相关。此外，甲基转移酶样蛋白3（Mettl3）的N6-甲基腺苷（m6A）修饰USP15，通过增加其mRNA稳定性上调其水平。这些发现为潜在发现新的HCC癌基因、鉴定有效靶点以及开发新型抗HCC药物和临床应用提供了理论依据。
