Guo Wei, Dong Zhi-Ming, Guo Yan-Li, Yang Zhi-Bin, Kuang Gang, Shan Bao-En
Hebei Cancer Institute,The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, 050011,P. R. China.
Ai Zheng. 2009 Dec;28(12):1298-303. doi: 10.5732/cjc.009.10236.
Thrombospondin-1(TSP1) is an inhibitor of angiogenesis and its promoter hypermethylation has been found resulting in gene silencing in some primary human carcinomas. This study was to investigate the promoter methylation of TSP1 and its correlation with TGF-beta1 level and T cell immunity in gastric cardia adenocarcinoma (GCA).
Methylation specific polymerase chain reaction (MSP) approach and immunohistochemistry method were used to examine the methylation status of the 5' CpG island and expression of TSP1 protein, respectively. The level of TGF-beta1 was measured by ELISA and T cell immunity of GCA by flow cytometry analysis.
TSP1 methylation frequency was significantly higher in tumor specimens than in corresponding normal tissues (35.4% vs. 3.1%, P<0.001) and significantly higher in Stages III and IV tumor tissues than in Stages I and II tumor tissues (P<0.05). TSP1 protein expression was significantly lower in the tumor tissues than in corresponding normal tissues (P<0.05) and statistically correlated with its methylation status (P<0.01). The total level of TGF-beta1 was significantly higher in the GCA patients than in healthy controls(P<0.05) and significantly higher in Stages III and IV GCA patients than in Stages I and II GCA patients (P<0.05). The level of active TGF-beta1 was significantly higher in the GCA patients with hypermethylation of TSP1 than in the GCA patients without methylation of TSP1(P<0.05), but there was no statistical difference(P>0.05). The function of T cell immunity was significantly different between the GCA patients with hypermethylation of TSP1 and those without methylation of TSP1 (P<0.05).
Promoter hypermethylation of TSP1 may play an important role in the development of GCA and reflect the biological behaviours of GCA.
血小板反应蛋白-1（TSP1）是一种血管生成抑制剂，在一些原发性人类癌症中发现其启动子高甲基化会导致基因沉默。本研究旨在探讨TSP1启动子甲基化及其与贲门腺癌（GCA）中转化生长因子-β1（TGF-β1）水平和T细胞免疫的相关性。
分别采用甲基化特异性聚合酶链反应（MSP）法和免疫组织化学法检测5' CpG岛的甲基化状态和TSP1蛋白的表达。采用酶联免疫吸附测定（ELISA）法检测TGF-β1水平，通过流式细胞术分析GCA的T细胞免疫情况。
肿瘤标本中TSP1甲基化频率显著高于相应正常组织（35.4%对3.1%，P<0.001），且III期和IV期肿瘤组织中的甲基化频率显著高于I期和II期肿瘤组织（P<0.05）。肿瘤组织中TSP1蛋白表达显著低于相应正常组织（P<0.05），且与其甲基化状态具有统计学相关性（P<0.01）。GCA患者中TGF-β1的总水平显著高于健康对照（P<0.05），III期和IV期GCA患者中的TGF-β1总水平显著高于I期和II期GCA患者（P<0.05）。TSP1高甲基化的GCA患者中活性TGF-β1水平显著高于未发生TSP1甲基化的GCA患者（P<0.05），但差异无统计学意义（P>0.05）。TSP1高甲基化的GCA患者与未发生TSP1甲基化的GCA患者之间T细胞免疫功能存在显著差异（P<0.05）。
TSP1启动子高甲基化可能在GCA的发生发展中起重要作用，并反映GCA的生物学行为。
