食管癌组织中PTEN基因启动子区高甲基化的临床特征

Clinical Characteristics of Promoter Hypermethylation of PTEN Gene in Esophageal Carcinoma Tissues

目的探讨PTEN基因的甲基化状态与食管癌发生、发展的关系,以及PTEN基因的甲基化与其mRNA表达的关系。方法首先采用甲基化特异性聚合酶链反应(methylation specific PCR,MSP)方法,检测94例食管鳞状细胞癌(esophageal squamous cell carcinoma,ESCC)患者PTEN基因启动子区的甲基化状态,分析其与食管癌发病、淋巴结转移、浸润深度及临床病理分期的关系。其次应用反转录聚合酶链反应(reverse transcription PCR,RT-PCR)方法检测PTEN基因mRNA表达情况,分析PTEN基因甲基化状态与其基因mRNA表达的关系。结果食管癌组织中,PTEN基因的甲基化发生率为45.7%(43/94),而相应的病变周围的正常食管组织中甲基化频率为11.7%(11/94),PTEN基因的甲基化在食管癌组织中显著高于食管正常组织(P=0.00);食管癌中,淋巴结转移阳性组PTEN基因甲基化频率为62.9%(22/35),显著性高于阴性组(35.6%,21/59)(P=0.01);浸润深度T1+T2组和T3+T4组PTEN基因甲基化频率以及临床病理分期Ⅰ+Ⅱ期组和Ⅲ+Ⅳ期组PTEN基因甲基化频率差异均无统计学意义(P=0.23和P=0.14)。PTEN mRNA表达阴性的肿瘤组织中,74.2%(23/31)发生了PTEN基因的甲基化,PTEN基因mRNA阴性表达与其甲基化状态有显著的相关性(Phi=-0.40,P=0.00)。结论食管癌组织中PTEN基因的甲基化高频率与食管癌的发生和淋巴结转移密切相关;此外,PTEN基因甲基化是引起其mRNA阴性表达(失表达)的重要原因。

Objective To explore the association of PTEN gene hypermethylation status and the occurrence and development of esophageal squamous cell cancer(ESCC), and the relationship of PTEN gene hypermethylation with mRNA expression. Methods Firstly, PTEN methylated pattern was determined by methylation specific polymerase chain-reaction(MSP) among 94 ESCC patients. In the meantime, the relationship between PTEN methylated pattern and the risk of ESCC, lymphatic metastasis, penetration, pTNM staging were analyzed. Secondly, PTEN mRNA expression was detected by reverse transcription PCR(RT-PCR), and the relationship between PTEN genes methylation and mRNA expression was analyzed. Results The frequency of PTEN gene hypermethylation among the 94 tumor tissues was 45.7%(43/94), while that in adjacent normal tissues was 11.7%(11/94), with significant difference(P=0.00). The frequency of PTEN hypermethylation in the positive lymphatic metastasis group(62.9%, 22/35) was significantly higher than that in negative lymphatic metastasis group(35.6%, 21/59, P=0.01). No significant difference were observed for the frequency of PTEN hypermethylation between two groups with different depth of penetration(P=0.23) or different pTNM staging(P=0.14). Among the tumor tissues with negative mRNA expression of PTEN, 74.2%(23/31) cases showed PTEN hypermethylation. The lost mRNA expression of PTEN was significantly associated with PTEN hypermethylation(Phi=-0.40, P=0.00). Conclusion The high frequency of PTEN hypermethylation was associated with the development and lymphatic metastasis of ESCC. In addition, PTEN hypermethylation is one of the reasons for PTEN inactivation.