中文摘要：

目的检测散发性结直肠癌组织p33ING1b启动子甲基化情况,探讨p33ING1b在散发性结直肠癌中转录抑制的可能机制。方法选择2008年10月—2012年3月在广西医科大学第一附属医院结直肠肛门外科住院的散发性结直肠癌患者63例,收集其癌组织及相应癌旁组织切除标本;同时选择在我院行吻合器痔上黏膜环切术（PPH）患者13例,收集其术后痔上黏膜组织。采用巢式-甲基化特异性PCR（nMSP法）检测p33ING1b启动子甲基化情况,RT-PCR检测癌组织p33ING1b mRNA表达水平;采用5-氮-2-脱氧胞苷（5-aza-dC）对人结直肠癌细胞株DLD-1、Caco-2进行去甲基化干预实验。结果癌组织p33ING1b启动子甲基化阳性率为82.5%（52/63）,癌旁组织为34.2%（27/63）,痔上黏膜组织未检测出p33ING1b启动子甲基化,癌组织p33ING1b启动子甲基化阳性率高于癌旁组织和痔上黏膜组织（χ^2=21.21,P〈0.001;χ^2=33.98,P〈0.001）。不同性别、年龄、肿瘤位置、分化程度及有无淋巴结转移、远处转移患者癌组织p33ING1b启动子甲基化阳性率比较,差异均无统计学意义（P〉0.05）;不同Dukes分期患者癌组织p33ING1b启动子甲基化阳性率比较,差异有统计学意义（P〈0.05）。p33ING1b启动子甲基化癌组织p33ING1b mRNA相对表达量为（0.62±0.15）,低于p33ING1b启动子非甲基化癌组织的（0.75±0.17）（t=2.553,P〈0.05）。5-aza-dC干预后,人结直肠癌细胞株DLD-1、Caco-2的p33ING1b启动子甲基化均被逆转,且p33ING1b mRNA相对表达量较干预前升高（P〈0.05）。结论 p33ING1b启动子甲基化与散发性结直肠癌存在关联,并可能通过抑制p33ING1b mRNA的表达参与结直肠癌的发生和发展。

英文摘要：

Objective To investigate the expression of promoter methylation of p33ING1b in sporadic colorectal cancer（SCRC）,to analyze the its mechanism.Methods Samples of cancer and adjacent para-carcinoma tissues were collected in 63 SCRC patients hospitalized in this hospital from October 2008 to March 2012,and the hemorrhoids mucosa tissues collected in 13 patients who had procedure for prolapse and hemorrhoids（PPH）.Promoter methylation of p33ING1b was determined by Nested-methylation specific PCR（nMSP method）,expression of p33ING1b mRNA by RT-PCR.5-aza-2-deoxycytidine（5-aza-dC） was used to do intervene human colorectal cancer cell line DLD-1,Caco-2 demethylation.Results The positive rate of promoter methylation of p33ING1b was 82.5%（52 /63） in cancer tissues,34.2%（27 /63） in para-carcinoma tissues.No promoter methylation of p33ING1 was detected in hemorrhoids mucosa tissues.The positive rate of promoter methylation of p33ING1 was higher in cancer tissues than in para-carcinoma and hemorrhoids mucosa tissues（χ^2= 21.21,P〈0.001;χ^2= 33.98,P〈0.001）.There was no significant difference in positive rate of promoter methylation of p33ING1b between patients of different genders,ages,with different cancer locations,degrees of differentiation,lymph node metastasis,distant metastasis（P〈0.05）,there was between patients with different Dukes stages（P〈0.05）.The relative transcript level of p33ING1b mRNA was（0.62 ± 0.15） in cancer tissues of promoter methylation of p33ING1b,lower than in non-methylation cancer tissues（0.75 ± 0.17）（t = 2.553,P〈0.05）.After 5-aza-dC intervention,promoter methylation of p33ING1b of human colorectal cancer cell line DLD-1,Caco-2 was reversed,and relative transcript level of p33ING1b mRNA was higher than before intervention（P〈0.05）.Conclusion The promoter methylation of p33ING1b,related to SCRC,is involved in the genesis and development of colorectal cancer by inhibiting the expression of p33ING1b mRNA.