Wang Jiahong, Liao Jianping, Cheng Ye, Chen Meirong, Huang Aimin
Department of Pathology, School of Basic Medical Sciences, Fujian Medical University, 88 Jiaotong Road, Fuzhou, Fujian 350004, China.
Institute of Oncology, Fujian Medical University, 88 Jiaotong Road, Fuzhou, Fujian 350004, China.
JHEP Rep. 2024 Dec 20;7(4):101306. doi: 10.1016/j.jhepr.2024.101306. eCollection 2025 Apr.
BACKGROUND & AIMS: Lysosome-associated protein transmembrane 4β (LAPTM4B) is an oncogene implicated in the malignant progression of hepatocellular carcinoma (HCC). Previous research established a strong association between LAPTM4B and HCC stemness. However, specific mechanisms by which LAPTM4B regulates and maintains the stemness of liver cancer stem cells remain unclear. Therefore, we investigated the effects of LAPTM4B on the stemness regulation of cluster of differentiation 133 (CD133) liver cancer stem-like cells (CSLCs).
We used RNA interference and overexpression techniques in both and models. The involvement of LAPTM4B in wingless/integrated (WNT)/β-catenin signaling was examined through western blotting, immunofluorescence, and immunoprecipitation. The impact of LAPTM4B on β-catenin phosphorylation and ubiquitination was analyzed to elucidate its role in promoting stemness. Clinical relevance was evaluated in an in-house cohort of 105 specimens from patients with HCC through immunohistochemical and microarray analysis, enabling investigation of correlations with clinical outcomes.
LAPTM4B promoted the self-renewal ability, chemoresistance, and tumorigenicity of CD133 CSLCs. Mechanistically, aberrant LAPTM4B upregulation facilitated β-catenin nuclear translocation (nucleocytoplasmic separation assay, <0.001) and inhibited its phosphorylation ( <0.01). In addition, LAPTM4B interacts with the deubiquitinating enzymes ubiquitin carboxyl-terminal hydrolase (USP)-1 and USP14, reducing β-catenin ubiquitination. Furthermore, patients with high LAPTM4B and β-catenin expression had markedly shorter 3-year overall survival rate (42.9% 74.4%; hazard ratio, 5.174; 95% CI 2.280-11.741, <0.001).
LAPTM4B promotes CD133 CSLC stemness by activating WNT/β-catenin signaling by inhibiting β-catenin phosphorylation and ubiquitination degradation. The role of LAPTM4B in regulating WNT/β-catenin signaling suggests that LAPTM4B serves as a therapeutic target for impairing HCC stemness and progression.
LAPTM4B contributes significantly to CD133 CSLC stemness and inhibits β-catenin phosphorylation and ubiquitination degradation, activating WNT/β-catenin signaling. WNT inhibitors suppress LAPTM4B-induced CD133 CSLC stemness. Thus, targeting the LAPTM4B-WNT/β-catenin axis could improve antitumor efficacy.
溶酶体相关蛋白跨膜4β（LAPTM4B）是一种致癌基因，与肝细胞癌（HCC）的恶性进展有关。先前的研究证实LAPTM4B与肝癌干细胞特性之间存在密切关联。然而，LAPTM4B调节和维持肝癌干细胞干性的具体机制仍不清楚。因此，我们研究了LAPTM4B对分化簇133（CD133）肝癌干细胞样细胞（CSLCs）干性调节的影响。
我们在体内和体外模型中使用了RNA干扰和过表达技术。通过蛋白质免疫印迹、免疫荧光和免疫沉淀检测LAPTM4B在无翅/整合（WNT）/β-连环蛋白信号通路中的作用。分析LAPTM4B对β-连环蛋白磷酸化和泛素化的影响，以阐明其在促进干细胞特性方面的作用。通过免疫组织化学和微阵列分析，对来自105例HCC患者的内部队列标本进行临床相关性评估，从而研究其与临床结局的相关性。
LAPTM4B促进了CD133 CSLCs的自我更新能力、化疗耐药性和致瘤性。从机制上讲，LAPTM4B异常上调促进了β-连环蛋白的核转位（核质分离试验，P<0.001）并抑制了其磷酸化（P<0.01）。此外，LAPTM4B与去泛素化酶泛素羧基末端水解酶（USP）-1和USP14相互作用，减少了β-连环蛋白的泛素化。此外，LAPTM4B和β-连环蛋白高表达的患者3年总生存率明显较短（42.9%对74.4%；风险比，5.174；95%CI 2.280-11.741，P<0.001）。
LAPTM4B通过抑制β-连环蛋白磷酸化和泛素化降解来激活WNT/β-连环蛋白信号通路，从而促进CD133 CSLCs的干性。LAPTM4B在调节WNT/β-连环蛋白信号通路中的作用表明，LAPTM4B可作为损害肝癌干细胞特性和进展的治疗靶点。
LAPTM4B对CD·133 CSLCs干性有显著贡献，并抑制β-连环蛋白磷酸化和泛素化降解，激活WNT/β-连环蛋白信号通路。WNT抑制剂可抑制LAPTM4B诱导的CD·I33 CSLCs干性。因此，靶向LAPTM4B-WNT/β-连环蛋白轴可提高抗肿瘤疗效。
