摘要
目的探讨分泌型卷曲相关蛋白(sFRP)家族基因启动子CpG岛甲基化在结直肠肿瘤发生、发展中的作用。方法应用5-氮杂-2’-脱氧胞苷(DAC)和曲古菌素A(TSA)对结直肠癌细胞系RKO、HCT116和SW480进行去甲基化处理。甲基特异性PCR和逆转录PCR分别检测结直肠肿瘤组织及细胞系中sFRP基因甲基化和mRNA表达。结果正常大肠黏膜不存在sFRP基因甲基化。sFRP1、sFRP2和sFRP5在结直肠腺癌、腺瘤和异常隐窝灶(ACF)中均存在高频率甲基化,sFRP1甲基化率>85%,sFRP2甲基化率>75%,sFRP5甲基化率>50%,腺癌、腺瘤和ACF间sFRP基因甲基化率差异无统计学意义(P>0.05),但均高于正常黏膜及瘤旁正常组织(P<0.05)。3种结直肠癌细胞系RKO、HCT116和SW480均存在sFRP基因甲基化,甲基化的sFRP基因mRNA失表达。联合使用DAC和TSA能有效恢复结直肠癌细胞系的sFRP基因表达。结论在ACF中,sFRP基因家族已出现高频率甲基化,是结直肠肿瘤发生常见的早期事件,sFRP1、sFRP2和sFRP5甲基化可能成为早期发现结直肠肿瘤的生物学标志。去甲基化能有效恢复基因表达,可能成为治疗肿瘤的有效手段。
Objective To investigate the functions of promoter hypermethylation of secreted frizzled-related protein （sFRP） genes in colorectal tumorigenesis and progression. Methods Three colorectal cancer cell lines, RKO, HCTll6 and SW480, were treated by 5-aza-2＇-deoxycytidine and trichostatin A for demethylation. The promoter hypermethylation and expression of sFRP genes in colorectal tumor tissue and colorectal cancer cell lines were detected by methylation-specific PCR and reverse transcription PCR, respectively. Results None of the normal colorectal mucosa tissues showed methylation of sFRP genes, sFRP1,2,4 and 5 were frequently methylated in colorectal adenocarcinoma, adenoma and aberrant crypt foci （ACF） （sFRP1 〉85% ,sFRP2 〉75% ,sFRP5 〉50% ）, the differences between any two of them were not significant （ P 〉 O. 05 ）. Methylation was more frequent in colorectal tumors than in normal mucosa and adjacent normal mucosa from patients with tumor. Hypermethylation of sFRP genes was present in three colorectal cancer cell lines. When sFRP genes were methylated, their corresponding mRNA expression was absent. After cells were treated by DAC/TSA combination, the silenced sFRP expression could be effectively re-expressed. Conclusion Hypermethylation of sFRP genes is a common early event in the evolution of colorectal tumors that occurs frequently in ACF. Methylation of sFRP1,2 and 5 genes might serve as biomarkers for the early detection of colorectal tumors. Demethylation can effectively reverse gene expression that appears possibly to be an effective way for tumor therapy.
出处
《中华肿瘤杂志》
CAS
CSCD
北大核心
2007年第11期842-845,共4页
Chinese Journal of Oncology
基金
教育部高等学校博士学科点专项科研基金资助项目(301090255)
