Objective To explore the role of the DACT2 gene in the occurrence and development of renal cell carcinoma(RCC).Methods The samples of RCC tissues and corresponding tumor-adjacent tissues after radical operation and normal kidney tissues were collected.The methylation specific PCR (MSP) and real time fluorescence reverse transcriptase-PCR (RT-PCR) methods were adopted to detect the methylation status and mRNA expression of DACT2.The streptavidin-peroxidase (SP) method labeled by immunohistochemistry peroxidase was used to examine the expression of β-catenin protein.Then the relationship between DACT2 gene methylation status and mRNA expression with the clinicopathologic characteristics was analyzed.The relationship between DACT2 gene methylation with mRNA and β-catenin expression was analysed,as well.Results The DACT2 mRNA relative expression level in RCC tissues was 0.427±0.025,which was significantly lower than (0.801±0.047) in tumor-adjacent tissues and (0.872±0.022) in normal tissue,the positive rate of DACT2 gene methylation in RCC tissues was 45.76%,which was significantly higher than 6.78% in tumor-adjacent tissues and 5.08% in normal tissues,the difference was statistically significant (P<0.05),while the difference between tumor-adjacent tissues and normal tissues had no statistical significance (P>0.05).The DACT2 gene mRNA expression level in RCC tissues and promoter area methylation occurrence rate had no obvious correlation with the clinical data such as patients age,gender,tumor size,clinical stage and Fuhrman grade (P>0.05).The DACT2 gene mRNA relative level in the methylation group was lower than that in the non-methylation group,the difference was statistically significant (P<0.05).The expression rate of β-catenin protein in cytoplasma in RCC tissues was higher than that in the tumor-adjacent tissues and normal tissues,the difference was statistically significant (P<0.05),moreover,DACT2 gen methylation had a positive correlation with β-catenin protein expression (r=0.324,P=0.012).Conclusion The decrease of DACT2 gene promoter area methylation and mRNA relative expression level may participate in the RCC occurrence,but has no relationship with RCC clinical progression.Methylation occurred in DACT2 gene promoter area may be one of reasons causing mRNA relative expression decrase.DACT2 gene methylation occurrence in RCC tissue might be related to the high expression of β-catenin.%目的 探讨DACT2基因在肾细胞癌(RCC)发生、发展中的作用.方法 收集该院2014年8月至2015年8月59例住院RCC患者肾癌根治术后RCC及相应癌旁组织、正常组织标本,分别应用甲基化特异性PCR(MSP)、实时荧光定量PCR(RT-PCR)法检测其DACT2基因甲基化状态、mRNA表达情况,应用免疫组织化学过氧化酶标记的链霉卵白素(SP)法检测其细胞质内β-catenin蛋白的表达,并分析RCC组织DACT2基因甲基化状态及mRNA表达与临床病理特征的关系,以及DACT2基因甲基化与mRNA及β-catenin表达的关系.结果 RCC组织中DACT2 mRNA相对表达水平(0.427±0.025)明显低于癌旁组织(0.801±0.047)和正常组织(0.872±0.022),RCC组织中DACT2基因甲基化阳性率(45.76%)明显高于癌旁组织(6.78%)及正常组织(5.08%),差异均有统计学意义(P<0.05),而癌旁组织与正常组织比较差异均无统计学意义(P>0.05).在RCC组织中DACT2基因mRNA相对表达水平及启动子区甲基化发生率与患者的年龄、性别、肿瘤大小、临床分期、Fuhrman分级等临床资料间均无明显相关性(P>0.05).甲基化组中DACT2基因的mRNA相对表达水平低于非甲基化组,差异有统计学意义(P<0.05).RCC组织中β-catenin蛋白在细胞质中的表达率高于癌旁组织和正常组织,差异有统计学意义(P<0.05),且DACT2基因甲基化与β-catenin蛋白表达呈正相关(r=0.324,P=0.012).结论 DACT2基因启动子区甲基化及其mRNA相对表达水平降低可能参与RCC的发生,但与RCC的临床进展无关,DACT2基因启动子区发生甲基化可能是引起其mRNA相对表达降低的原因之一,且肾癌组织DACT2基因甲基化的发生可能与β-catenin的高表达有关.
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