Qi Jian, Zhu You-qing, Luo Jun, Tao Wen-hui
The Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
Zhonghua Yi Xue Za Zhi. 2007 Jul 24;87(28):1954-7.
To investigate the functions of promoter hypermethylation of secreted Wnt-antagonist genes in colorectal tumorigenesis and progression.
Two colorectal cancer cell lines, HCT116 and SW480, were treated by 5-aza-2'-deoxycytidine (DAC) and trichostatin A (TSA) for demethylation. The promoter hypermethylation and expression of sFRP and WIF-1 genes in different stages of colorectal tumor and colorectal cancer cell lines were detected by methylation-specific PCR and reverse transcription PCR, respectively.
None of the normal colorectal mucosa samples showed methylated bands of any sFRP and WIF-1genes. Hypermethylation of sFRP1, 2, 4, 5 and WIF-1 was detected in 93.1% (67/72), 83.3% (60/72), 36.1% (26/72), 52.8% (38/72) and 84.7% (61/72) of adenocarcinomas, 87.9% (29/33), 81.8% (27/33), 24.2% (8/33), 57.6% (19/33) and 72.7% (24/33) of adenomas, 52.6%, 28.9%, 2.6%, 18.4%, 23.7% of the adjacent normal mucosa. Methylation was more frequently found in colorectal tumors than in normal mucosa and adjacent normal mucosa from patients with tumor (P < 0.05). No significant association between Wnt-antagonist genes hypermethylation and clinicopathological characteristics was found (P > 0.05). SFRP1, 2, 4, 5 and WIF-1 genes were methylated in HCT116 cell line. SFRP1, 2 and WIF-1 were methylated in SW480 cell line. The mRNA expression of sFRPs and WIF-1 genes was absent or significantly downregulated (P < 0.01) when they were methylated in two colorectal cancer cell lines. SFRP3 was expressed in two colorectal carcinoma cell lines. DAC/TSA combination treatment re-expressed the silenced sFRPs and WIF-1 genes mRNA expressions effectively. A single application of TSA could not re-express sFRPs and WIF-1 genes mRNA expressions. The influence of demethylation treatment on sFRP3 expression was minimal.
Hypermethylation of Wnt-antagonist genes is a common early event in the evolution of colorectal tumor. Methylation of sFRP1, 2, 5 and WIF-1 genes might serve as biomarkers for the early detection of colorectal tumor.
探讨分泌型Wnt拮抗剂基因启动子高甲基化在结直肠癌发生发展中的作用。
用5-氮杂-2'-脱氧胞苷（DAC）和曲古抑菌素A（TSA）处理两种结肠癌细胞系HCT116和SW480进行去甲基化。分别采用甲基化特异性PCR和逆转录PCR检测结直肠癌不同阶段及结肠癌细胞系中sFRP和WIF-1基因的启动子高甲基化及表达情况。
正常结直肠黏膜样本中未发现任何sFRP和WIF-1基因的甲基化条带。腺癌中sFRP1、2、4、5和WIF-1的高甲基化检出率分别为93.1%（67/72）、83.3%（60/72）、36.1%（26/72）、52.8%（38/72）和84.7%（61/72）；腺瘤中分别为87.9%（29/33）、81.8%（27/33）、24.2%（8/33）、57.6%（19/33）和72.7%（24/33）；肿瘤旁正常黏膜中分别为52.6%、28.9%、2.6%、18.4%、23.7%。结直肠癌中甲基化的发生率高于正常黏膜及肿瘤患者的肿瘤旁正常黏膜（P < 0.05）。未发现Wnt拮抗剂基因高甲基化与临床病理特征之间存在显著相关性（P > 0.05）。HCT116细胞系中SFRP1、2、4、5和WIF-1基因发生甲基化。SW480细胞系中SFRP1、2和WIF-1基因发生甲基化。在两种结肠癌细胞系中，当sFRPs和WIF-1基因发生甲基化时，其mRNA表达缺失或显著下调（P < 0.01）。SFRP3在两种结肠癌细胞系中均有表达。DAC/TSA联合处理可有效使沉默的sFRPs和WIF-1基因mRNA表达重新上调。单独应用TSA不能使sFRPs和WIF-1基因mRNA表达重新上调。去甲基化处理对SFRP3表达的影响最小。
Wnt拮抗剂基因高甲基化是结直肠癌发生发展过程中常见的早期事件。sFRP第1、2、5和WIF-1基因的甲基化可能作为结直肠癌早期检测的生物标志物。
Zotero 插件