NPTX2甲基化在胰腺癌中的定量检测及诊断应用

Quantitative analysis of NPTX2 hypermethylation in pancreatic cancer and its application in diagnosis of pancreatic cancer

目的:检测NPTX2甲基化水平在胰腺癌中变化并评价其用于胰腺癌诊断的价值。方法:在10例胰腺癌组织和10例癌旁正常胰腺组织中,分别应用定量RT-PCR和SYBR Green荧光掺入甲基化特异性定量检测法检测NPTX2 mRNA表达量及CpG岛的甲基化量。应用上述建立甲基化特异性定量检测方法分析NPTX2甲基化在胰腺癌及健康志愿者全血DNA中的差异。结果:NPTX2基因在胰腺癌组织中mRNA表达量低于癌旁正常胰腺组织(RQ,0.276±0.263vs3.526±3.037,P=0.001),而其甲基化指数(MI)较癌旁正常胰腺组织高[(9.02±7.52)%vs(1.28±0.98)%,P=0.003]。RQ与MI两者之间存在负相关关系(R=-0.552,P=0.012)。NPTX2基因MI在胰腺癌患者全血DNA中显著高于健康人[(1.80±1.76)%vs(0.84±0.45)%,P<0.05]。结论:在胰腺癌组织中NPTX2发生高甲基化变化,检测其在临床样品中的MI可辅助用于胰腺癌诊断。

Objective：To investigate the methylation level of NPTX2 gene in pancreatic cancer and assess its clinical value in diagnosis of pancreatic cancer. Methods： We detected the mRNA expression and methylation levels of NPTX2 gene by qRT-PCR and quantitative methylation with SYBR Green in 10 primary pancreatic carcinoma tissues and the matched adjacent normal tissues. The methylation levels of NPTX2 gene were then detected and compared using the above-mentioned method in the whole blood of patients with pancreatic ductal adenocarcinoma and healthy volunteers. Results： The relative quantification （RQ） of NPTX2 expression in pancreatic carcinoma tissues was significantly lower than that in the adjacent tissues （0. 276± 0. 263 vs 3. 526± 3. 037,P= 0. 001 ）. The result of quantitive methylation indicated that the methylation index （MI） of the carcinoma tissues was significantly higher than that of the adjacent tissues （[9.02 ± 7.52]% vs [1.28± 0. 98]%, P= 0. 003）. MI of NPTX2 gene was negatively correlated with RQ value （R= -0. 552,P=0. 012）. We also found that the MI of the whole blood DNA methylation of patients with pancreatic cancer was significantly higher than that of healthy volunteers （[1. 80 ± 1.76] % vs [0.84±0.45]%, P〈0. 05）. Conclusion： Our findings strongly suggest that NPTX2 gene is aberrantly hypermethyated in pancreatic ductal adenocarcinoma. Detection of MI of NPTX2 gene might be of great value for diagnosis of pancreatic cancer.