背景:食管胃结合部癌(EJC)是指在胃和食道之间的连接处发展的恶性肿瘤。TUSC1是最近发现的肿瘤抑制基因,以其参与各种类型的癌症而闻名。这项研究的目的是阐明DNA甲基化对TUSC1表达的调节作用及其在EJC进展中的作用。
方法:利用生物信息学软件分析TUSC1的表达,富集途径,和启动子区域的高度甲基化位点。使用定量逆转录聚合酶链反应(qRT-PCR)评估EJC中的TUSC1表达,蛋白质印迹(WB),和免疫组织化学。采用甲基化特异性PCR检测TUSC1的甲基化水平。分析TUSC1和5-AZA-2对肿瘤细胞增殖的影响,迁移,入侵,细胞周期,和细胞凋亡,包括CCK-8,集落形成,transwell,并进行流式细胞术。使用qRT-PCR和WB评估MDM2的表达。WB检测到p53和p-p53的表达,p-p53是EJC细胞增殖的标志物,上皮-间质转化,和凋亡。使用异种移植小鼠模型检查了TUSC1在体内肿瘤发生中的作用。
结果:TUSC1表达在EJC中显著下调。TUSC1的过表达和5-AZA-2治疗抑制了EJC细胞的恶性进展。在EJC,低甲基化水平促进TUSC1的表达。TUSC1上调抑制MDM2的表达并激活p53信号通路。该途径的失活减弱了TUSC1过表达对EJC细胞增殖的抑制作用,迁移,入侵,和其他行为。动物实验表明,TUSC1过表达在体内抑制EJC肿瘤的生长和转移。
结论:TUSC1通常在EJC中下调,并受甲基化调节。它通过介导p53通路抑制EJC肿瘤的恶性进展,提示其作为EJC诊断和治疗靶点的潜力。
BACKGROUND: Esophagogastric junction cancer (EJC) refers to malignant tumors that develop at the junction between the stomach and the esophagus. TUSC1 is a recently identified tumor suppressor gene known for its involvement in various types of cancer. The objective of this investigation was to elucidate the regulatory influence of DNA methylation on TUSC1 expression and its role in the progression of EJC.
METHODS: Bioinformatics software was utilized to analyze the expression of TUSC1, enriched pathways, and highly methylated sites in the promoter region. TUSC1 expression in EJC was assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot (WB), and immunohistochemistry. Methylation-specific PCR was employed to detect the methylation level of TUSC1. To analyze the effects of TUSC1 and 5-AZA-2 on tumor cell proliferation, migration, invasion, cell cycle, and apoptosis, several assays including CCK-8, colony formation, transwell, and flow cytometry were conducted. The expression of MDM2 was assessed using qRT-PCR and WB. WB detected the expression of p53, and p-p53, markers for EJC cell proliferation, epithelial-mesenchymal transition, and apoptosis. The role of TUSC1 in tumor occurrence in vivo was examined using a xenograft mouse model.
RESULTS: TUSC1 expression was significantly downregulated in EJC. Overexpression of TUSC1 and treatment with 5-AZA-2 inhibited the malignant progression of EJC cells. In EJC, low methylation levels promoted the expression of TUSC1. Upregulation of TUSC1 suppressed the expression of MDM2 and activated the p53 signaling pathway. Inactivation of this pathway attenuated the inhibitory effect of TUSC1 overexpression on EJC cell proliferation, migration, invasion, and other behaviors. Animal experiments demonstrated that TUSC1 overexpression inhibited EJC tumor growth and metastasis in vivo.
CONCLUSIONS: TUSC1 was commonly downregulated in EJC and regulated by methylation. It repressed the malignant progression of EJC tumors by mediating the p53 pathway, suggesting its potential as a diagnostic and therapeutic target for EJC.