背景:肝细胞癌(HCC)是一种常见的恶性肿瘤,谷氨酰胺对肿瘤细胞至关重要。谷氨酰胺转运体SLC1A5在肿瘤进展和经动脉化疗栓塞(TACE)疗效中的作用正在研究中。本研究旨在确定SLC1A5表达对HCC预后和TACE疗效的影响,并阐明其机制。
方法:SLC1A5在肝癌中的表达,与患者预后的相关性,和对TACE的反应在开放获取肝癌数据集中进行了研究,并在我们的队列中得到证实。此外,SLC1A5表达与缺氧的相关性,血管生成和免疫浸润分析,并通过免疫组织化学验证,免疫荧光和转录组测序。构建SLC1A5表达敲低或过表达的肝癌细胞系,和细胞增殖,菌落形成,凋亡,测量了体内异种移植肿瘤的迁移和药物敏感性。进行基因集富集分析以确定受SLC1A5影响的信号传导途径,并进行蛋白质印迹分析以检测蛋白质表达改变。
结果:SLC1A5在HCC组织中的表达更高,并且与低生存率和TACE耐药相关。缺氧可以刺激谷氨酰胺转运的上调,血管生成和SLC1A5表达。SLC1A5表达与缺氧和血管生成相关基因呈正相关,免疫检查点途径,巨噬细胞,Tregs,和其他免疫抑制细胞浸润。SLC1A5的敲减减少增殖,菌落形成,和移民,但细胞凋亡增加,对化疗药物的敏感性增加。SLC1A5的下调导致波形蛋白和N-钙黏着蛋白表达的减少,然而E-cadherin表达增加。SLC1A5的上调增加了波形蛋白和N-钙粘蛋白的表达,同时减少E-cadherin。在SLC1A5敲低肝癌细胞系中过表达β-连环蛋白可以增加波形蛋白和N-钙黏着蛋白的表达,抑制E-cadherin表达,并增加迁移和耐药性。
结论:升高的SLC1A5与HCC患者的TACE抵抗和生存缩短有关。SLC1A5与缺氧呈正相关,血管生成,和免疫抑制。SLC1A5可能通过上皮-间质转化(EMT)途径介导HCC细胞迁移和耐药。
BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignant tumor, and glutamine is vital for tumor cells. The role of glutamine transporter SLC1A5 in tumor progression and transarterial chemoembolization (TACE) efficacy is under study. This research seeks to determine the impact of SLC1A5 expression on the prognosis and TACE efficacy of HCC and elucidate its mechanisms.
METHODS: SLC1A5 expression in HCC, correlation with patient outcomes, and response to TACE were studied in an open access liver cancer dataset and confirmed in our cohort. Additionally, the correlation between SLC1A5 expression and hypoxia, angiogenesis and immune infiltration was analyzed and verified by immunohistochemistry, immunofluorescence and transcriptome sequencing. Liver cancer cell lines with SLC1A5 expression knockdown or overexpression were constructed, and cell proliferation, colony formation, apoptosis, migration and drug sensitivity as well as in vivo xenograft tumor were measured. A gene set enrichment analysis was conducted to determine the signaling pathway influenced by SLC1A5, and a western blot analysis was performed to detect protein expression alterations.
RESULTS: SLC1A5 expression was higher in HCC tissue and associated with poor survival and TACE resistance. Hypoxia could stimulate the upregulation of glutamine transport, angiogenesis and SLC1A5 expression. The SLC1A5 expression was positively correlated with hypoxia and angiogenesis-related genes, immune checkpoint pathways, macrophage, Tregs, and other immunosuppressive cells infiltration. Knockdown of SLC1A5 decreased proliferation, colony formation, and migration, but increased apoptosis and increased sensitivity to chemotherapy drugs. Downregulation of SLC1A5 resulted in a decrease in Vimentin and N-cadherin expression, yet an increase in E-cadherin expression. Upregulation of SLC1A5 increased Vimentin and N-cadherin expression, while decreasing E-cadherin. Overexpression of β-catenin in SLC1A5-knockdown HCC cell lines could augment Vimentin and N-cadherin expression, suppress E-cadherin expression, and increase the migration and drug resistance.
CONCLUSIONS: Elevated SLC1A5 was linked to TACE resistance and survival shortening in HCC patients. SLC1A5 was positively correlated with hypoxia, angiogenesis, and immunosuppression. SLC1A5 may mediate HCC cell migration and drug resistance via Epithelial-mesenchymal transition (EMT) pathway.