Promoter methylation and differential expression of π-class glutathione S-transferase in endometrial carcinoma
Promoter methylation and differential expression of π-class glutathione S-transferase in endometrial carcinoma
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DOI：
10.1016/s1525-1578(10)60003-7
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发表时间：
2005-02-01
影响因子：
4.1
通讯作者：
Cheung, ANY
中科院分区：
文献类型：
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作者：
Chan, QKY;Khoo, US;Cheung, ANY
位于染色体11 q13上的π类谷胱甘肽S-转移酶（GSTP 1）编码H相代谢酶，其对活性亲电中间体进行解毒。该蛋白质还与人体内的类固醇激素相互作用。GSTP 1在子宫内膜癌中的作用尚未见报道。在这项研究中，我们的目的是确定GST P1的表达与基因的表观遗传和遗传变化的子宫内膜癌。分别采用组织芯片免疫组化和实时定量逆转录聚合酶链反应检测GST P1蛋白和mRNA的表达。通过甲基化特异性聚合酶链反应和亚硫酸氢盐测序研究其甲基化状态。通过cDNA测序分析GST P1编码区可能存在的突变。本文对97例有组织块和临床资料的子宫内膜癌进行了研究。我们的研究结果显示，68.0%（66/97）的病例显示蛋白质表达减少，而64%（16/25）显示mRNA表达减少; 30.9%（30/97）的病例在6种甲基化特异性聚合酶链反应中至少有一种表现出甲基化等位基因。甲基化状态与蛋白表达降低（P = 0.008）和mRNA表达降低（P = 0.003）显著相关。还观察到非CpG位点（包括CpCpG三核苷酸和CpT二核苷酸）的甲基化。cDNA测序未发现该基因编码区的遗传改变。肌层浸润程度与GST P1基因甲基化状态（P = 0.009）和蛋白表达（P = 0.036）均显著相关。我们推测GSTP 1基因启动子区的高甲基化可能作为一种动态调节机制，导致GSTP 1表达降低，这与子宫内膜癌的肌层浸润潜力有关。
pi-Class glutathione S-transferase (GSTP1), located on chromosome 11q13, codes for a phase H metabolic enzyme that detoxifies reactive electrophilic intermediates. The protein also interacts with steroid hormones in the human body. The role of GSTP1 in endometrial carcinoma has not been reported. In this study, we aimed at determining the expression of GSTP1 in relation to the epigenetic and genetic changes of the gene in endometrial carcinoma. The GSTP1 protein and mRNA expression was assessed by immunohistochemistry on tissue microarray and quantitative real-time reverse transcriptase-polymerase chain reaction, respectively. Its methylation status was studied by methylation-specific polymerase chain reaction and bisulfite sequencing. Possible mutations in coding region of GSTP1 were assessed by cDNA sequencing. Ninety-seven cases of endometrial carcinoma with available tissue blocks and clinical data were studied. Our results showed that 68.0% (66 of 97) of the cases showed reduced protein expression while 64% (16 of 25) showed reduced mRNA expression; 30.9% (30 of 97) of the cases demonstrated methylated alleles in at least one of the six methylation-specific polymerase chain reaction reactions. The methylation status significantly correlated with reduced protein expression (P = 0.008) and reduced mRNA expression (P = 0.003). methylation at non-CpG sites including CpCpG trinucleotides and CpT dinucleotides were also observed. cDNA sequencing did not reveal genetic alterations in coding region of the gene. The extent of myometrial invasion was found to be significantly correlated with both the methylation status (P = 0.009) and the protein expression (P = 0.036) of the GSTP1 gene. We postulated that hypermethylation of the GSTP1 gene promoter region may act as a dynamic regulation mechanism contributing to reduced GSTP1 expression, which is associated with myometrial invasion potential of the endometrial carcinoma.