背景:胃癌的发生发展是一个多因素的,多阶段,多基因异常积累过程。遗传和表观遗传机制在胃癌的分子机制中起着重要作用。DNA甲基化是研究最多的表观遗传表达机制之一。研究血管内皮生长因子受体3(VEGFR3)基因启动子甲基化状态与蛋白表达的相关性,以及它们与早期胃癌(EGC)病例的临床病理特征的关系。
方法:采用免疫组织化学分析和甲基化特异性PCR(MSP)检测50例EGC及其配对的正常胃粘膜组织中VEGFR3蛋白的表达和VEGFR3启动子甲基化状态。VEGFR3启动子的DNA甲基化水平,原位VEGFR3蛋白表达,并对EGC患者的临床病理特征进行统计学分析。
结果:EGC肿瘤组织中VEGFR3蛋白表达阳性率(60%)明显高于正常胃粘膜组织(10%)。EGC肿瘤组织中VEGFR3启动子的可检测甲基化频率(48%)显著低于正常胃粘膜组织(85%)。如预期,VEGFR3基因启动子的甲基化水平与VEGFR3蛋白的过表达呈负相关。此外,EGC患者VEGFR3基因启动子甲基化状态与淋巴结转移呈正相关(P<0.05),但与患者的性别无关,年龄,肿瘤大小,分化程度,或肿瘤浸润深度(P>0.05)。
结论:VEGFR3基因启动子的低甲基化是EGC肿瘤组织中VEGFR3基因过表达的主要机制之一,与EGC患者的淋巴结转移有关。VEGFR3的DNA甲基化有望成为EGC的分子诊断和预后生物标志物。
BACKGROUND: The occurrence and development of gastric cancer is a multi-factor, multi-stage, multi-gene abnormal accumulation process. Both genetic and epigenetic mechanisms play an important role in the molecular mechanism of gastric cancer. DNA methylation is one of the most studied epigenetic expression mechanisms. To study the correlation between gene promoter methylation status and protein expression of vascular endothelial growth factor receptor 3 (VEGFR3), as well as their association with clinicopathological features in early gastric cancer (EGC) cases.
METHODS: Immunohistochemical analysis and methylation-specific PCR (MSP) were used to detect the expression of VEGFR3 protein and methylation status of the VEGFR3 promoter in 50 cases of EGC and their paired normal gastric mucosa tissues. The level of DNA methylation of the VEGFR3 promoter, in situ VEGFR3 protein expression, and the clinicopathological characteristics of EGC patients were statistically analyzed.
RESULTS: The positive rate of VEGFR3 protein expression in EGC tumor tissue (60%) was significantly higher than that in the normal gastric mucosa (10%). The detectable methylation frequency of VEGFR3 promoter in EGC tumor tissue (48%) was significantly lower than that in the normal gastric mucosa (85%). As anticipated, the methylation level of the VEGFR3 gene promoter was negatively associated with the overexpression of VEGFR3 protein. In addition, methylation status of the VEGFR3 gene promoter was positively correlated with lymph node metastasis in EGC patients (P<0.05), but was not linked to patients\' gender, age, tumor size, degree of differentiation, or tumor invasion depth (P>0.05).
CONCLUSIONS: Hypomethylation of the VEGFR3 gene promoter is one of the major mechanisms underlying VEGFR3 gene overexpression in EGC tumor tissues and is related to lymph node metastasis in EGC patients. DNA methylation of VEGFR3 is expected to become a molecular diagnostic and prognostic biomarker for EGC.