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目的探讨鼻咽癌组织中血小板反应蛋白1(thrombospondin 1,THBS1)基因启动子甲基化对其mRNA及蛋白水平表达的影响及与鼻咽癌临床病理特征的相关性。方法收集51例新鲜鼻咽癌标本及18例正常鼻咽黏膜标本。应用逆转录PCR检测THBS1 mRNA的表达,Western blot检测THBS1蛋白的表达,甲基化特异性PCR检测THBS1基因启动子区CpG岛甲基化。结果鼻咽癌组织中THBS1 mRNA(0.309±0.162)及蛋白(0.214±0.127)表达下调,与正常鼻咽黏膜组织对照组[分别为(0.528±0.096)、(0.514±0.118)]相比差异均具有统计学意义(P<0.01);鼻咽癌组织中基因启动子区高甲基化率显著高于其在正常鼻咽黏膜组织,差异有统计学意义(P<0.01)。鼻咽癌组织中THBS1 mRNA及蛋白表达下调均与THBS1基因启动子区高甲基化有关(P<0.01)。基因启动子区高甲基化率与鼻咽癌临床TNM分期、局部侵袭、淋巴结转移及远处转移呈正相关,差异均具有统计学意义(P<0.05)。结论鼻咽癌组织中存在THBS1 mRNA及蛋白异常低表达及启动子区的高甲基化,THBS1基因高甲基化可能抑制THBS1 mRNA及蛋白的表达,在鼻咽癌发生、发展中发挥重要作用。
Objective To investigate the effect of promoter methylation of thrombospondin 1 (THBS1) gene on the expression of mRNA and protein in nasopharyngeal carcinoma (NPC) and its correlation with the clinicopathological features of nasopharyngeal carcinoma. Methods 51 fresh nasopharyngeal carcinoma specimens and 18 normal nasopharyngeal mucosa specimens were collected. The expression of THBS1 mRNA was detected by RT-PCR, the expression of THBS1 protein by Western blot, and the methylation of CpG island in THBS1 gene promoter region by methylation-specific PCR. Results The expressions of THBS1 mRNA (0.309 ± 0.162) and protein (0.214 ± 0.127) in nasopharyngeal carcinoma tissues were significantly lower than those in normal nasopharyngeal mucosa tissues [(0.528 ± 0.096) and (0.514 ± 0.118, respectively] (P <0.01). The hypermethylation rate of gene promoter region in nasopharyngeal carcinoma was significantly higher than that in normal nasopharyngeal mucosa (P <0.01). The down-regulation of THBS1 mRNA and protein in NPC tissues was associated with hypermethylation of THBS1 promoter (P <0.01). The hypermethylation rate of gene promoter region was positively correlated with the clinical TNM staging, local invasion, lymph node metastasis and distant metastasis of nasopharyngeal carcinoma, with statistical significance (P <0.05). CONCLUSIONS: The abnormal expression of THBS1 mRNA and protein and the hypermethylation of THBS1 gene in nasopharyngeal carcinoma may play an important role in the occurrence and development of nasopharyngeal carcinoma. The hypermethylation of THBS1 gene may inhibit the expression of THBS1 mRNA and protein.