结直肠癌γ-synuclein基因启动子CpG岛的去甲基化及其临床意义  

Demethylation of the γ-synuclein gene CpG island in colorectal cancer and its clinical significance

作　　者：叶青[1] 冯波[1] 彭远飞[1] 蔡劬[1] 陈雪华[1] 俞焙秦[1] 马君俊[1] 陆爱国[1] 李健文[1] 王明亮[1] 刘炳亚[1] 郑民华[1] 

机构地区：[1]上海交通大学医学院附属瑞金医院普通外科上海市微创外科临床医学中心上海市消化外科研究所,200025

出　　处：《中华胃肠外科杂志》2010年第6期440-444,共5页Chinese Journal of Gastrointestinal Surgery

摘　　要：目的 探讨结直肠癌中γ-synuclein基因的表达与启动子区CpG岛甲基化修饰之间的关系,以及γ-synuclein基因去甲基化水平与结直肠癌临床病理特征的关系.方法 采用半定量RT-PCR法检测30例结直肠癌和相应癌旁组织中γ-synuclein基因的表达及去甲基化试剂5-杂氮-2＇-脱氧胞苷（5-Aza-C）干预对结直肠癌细胞COLO205、LoVo和SW480的γ-synuclein基因表达的影响.采用亚硫酸氢盐修饰测序（BSP）法检测5-Aza-C处理前后CpG岛的甲基化情况.采用巢式甲基化PCR（NMSP）及实时荧光定量MSP法检测67例结直肠癌组织和30例相应癌旁组织中γ-synuclein基因的甲基化状态,并分析其与临床病理特征的关系.结果结直肠癌组织中γ-synuclein mRNA的表达水平0.66±0.34,高于相应癌旁组织的0.45±0.26,差异有统计学意义（P=0.011）.5-Aza-C处理后,COLO205、LoVo和SW480细胞γ-synuclein mRNA表达水平明显上升,同时γ-synuclein基因启动子区CpG岛的甲基化水平明显降低.80.0%（24/30）的结直肠癌组织和50.0%（15/30）的相应癌旁组织的γ-synuclein基因被去甲基化,结直肠癌组织中γ-synuclein基因去甲基化的趋势明显强于相应癌旁组织（P=0.030）.γ-synuclein基因的去甲基化水平与结直肠癌的淋巴结转移、临床病理分期及远处转移有关.结论 结直肠癌中γ-synuclein基因的上调表达与启动子区CpG岛的去甲基化状态有一定关联,γ-synuclein基因的去甲基化水平有望成为结直肠癌患者判断预后的潜在标志物.Objective To explore the relationship between γ-synuclein gene expression and CpG island demethylation in colorectal cancer （CRC）, and the relationship between the demethylation and clinicopathological factors of CRC. Methods The expression of γ-synuclein mRNA was examined in 30 pairs of tumor tissues and tumor-matched non-neoplastic adjacent tissues （NNAT） by RT-PCR.CRC cell lines including COLO205, LoVo, and SW480 were used and treated with a demethylating agent, 5-aza-2＇-deoxycytidine （5-aza-C）. Before and after the treatment, the expression of γ-synuclein mRNA in the cells was determined by RT-PCR, and bisulfite sequencing PCR was also used to analyze methylation status of CpG island. The methylation status of γ-synuclein was then examined in 67 CRC samples and 30 NNAT samples by nested methylation-specific PCR （NMSP） and real time methylationspecific PCR （real-time MSP）. The relationship between the demethylation of γ-synuclein in CRC and clinicopathological factors was analyzed. Results The mean γ-synuclein mRNA expression was 0.66±0.34 in CRC samples, which was much higher than 0.45±0.26 in NNAT samples （P=0.011）. 5-aza-C could induce expression and demethylation of γ-synuclein in COLO205, LoVo and SW480 cells. Γ-Synuclein gene was demethylated in 80.0%（24/30） of the CRC samples and 50.0%（15/30） of the NNAT samples.The demethylated status of γ-synuclein was much higher in CRC samples than that in NNAT samples （P=0.030）, and was significantly correlated with clinical stage, lymph node involvement, and distant metastasis of CRC （P〈0.05）. Conclusion The upregulation of γ-synuclein expression in CRC is primarily attributed to the demethylation of CpG island, which may be used as a marker for prognosis.

关 键 词：结直肠肿瘤 Γ-SYNUCLEIN 甲基化 5-杂氮-2'-脱氧胞苷 

分 类 号：R735.3[医药卫生—肿瘤]