Liu Yachen, Wu Meng, Xu Shuxiang, Niu Xiangjie, Liu Weiling, Miao Chuanwang, Lin Ai, Xu Yang, Yu Lili
Department of Thoracic Surgery, Fudan University Shanghai Cancer Center, Shanghai, China.
Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
Cell Biosci. 2023 Mar 30;13(1):67. doi: 10.1186/s13578-023-01016-4.
The ubiquitin-proteasome and autophagy-lysosomal systems collaborate in regulating the levels of intracellular proteins. Dysregulation of protein homeostasis is a central feature of malignancy. The gene encoding 26S proteasome non-ATPase regulatory subunit 2 (PSMD2) of the ubiquitin-proteasome system is an oncogene in various types of cancer. However, the detailed role of PSMD2 in autophagy and its relationship to tumorigenesis in esophageal squamous cell carcinoma (ESCC) remain unknown. In the present study, we have investigated the tumor-promoting roles of PSMD2 in the context of autophagy in ESCC.
Molecular approaches including DAPgreen staining, 5-Ethynyl-2'-deoxyuridine (EdU), cell counting kit 8 (CCK8), colony formation, transwell assays, and cell transfection, xenograft model, immunoblotting and Immunohistochemical analysis were used to investigate the roles of PSMD2 in ESCC cells. Data-independent acquisition (DIA) quantification proteomics analysis and rescue experiments were used to study the roles of PSMD2 in ESCC cells.
We demonstrate that the overexpression of PSMD2 promotes ESCC cell growth by inhibiting autophagy and is correlated with tumor progression and poor prognosis of ESCC patients. DIA quantification proteomics analysis shows a significant positive correlation between argininosuccinate synthase 1 (ASS1) and PSMD2 levels in ESCC tumors. Further studies indicate that PSMD2 activates the mTOR pathway by upregulating ASS1 to inhibit autophagy.
PSMD2 plays an important role in repressing autophagy in ESCC, and represents a promising biomarker to predict prognosis and a therapeutic target of ESCC patients.
泛素-蛋白酶体系统和自噬-溶酶体系统共同调节细胞内蛋白质水平。蛋白质稳态失调是恶性肿瘤的一个核心特征。泛素-蛋白酶体系统中编码26S蛋白酶体非ATP酶调节亚基2（PSMD2）的基因是多种癌症中的一个癌基因。然而，PSMD2在自噬中的具体作用及其与食管鳞状细胞癌（ESCC）肿瘤发生的关系仍不清楚。在本研究中，我们研究了PSMD2在ESCC自噬背景下的促肿瘤作用。
采用包括DAPgreen染色、5-乙炔基-2'-脱氧尿苷（EdU）、细胞计数试剂盒8（CCK8）、集落形成、transwell实验、细胞转染、异种移植模型、免疫印迹和免疫组化分析等分子方法，研究PSMD2在ESCC细胞中的作用。采用数据非依赖采集（DIA）定量蛋白质组学分析和拯救实验研究PSMD2在ESCC细胞中的作用。
我们证明，PSMD2的过表达通过抑制自噬促进ESCC细胞生长，并与ESCC患者的肿瘤进展和不良预后相关。DIA定量蛋白质组学分析显示，精氨酸琥珀酸合酶1（ASS1）与ESCC肿瘤中PSMD2水平呈显著正相关。进一步研究表明，PSMD2通过上调ASS1激活mTOR通路以抑制自噬。
PSMD2在ESCC抑制自噬中起重要作用，是预测预后的有前景的生物标志物和ESCC患者的治疗靶点。
