Gao Nan, Chen Wei-Chang, Cen Jian-Nong
Department of Gastroenterology, First Hospital of Suzhou University, Suzhou 215006, China.
Zhonghua Zhong Liu Za Zhi. 2008 May;30(5):361-4.
This study was designed to clarify the significance of DNA methylation in the expression of runt-related transcription factor 3 (Runx3) gene.
Reverse transcription-PCR (RT-PCR) was used to measure the expression level of Runx3 mRNA in paired samples of primary gastric cancer and corresponding non-cancerous gastric mucosa, taken from surgical specimens of 70 gastric cancer patients. Western blot was used to detect the protein expression level of Runx3 gene. The promoter methylation status of Runx3 gene was detected by methylation specific PCR (MSP). Furthermore, RT-PCR was used to mesure the expression of DNA methyltransferase 1 (Dnmtl) mRNA . The correlation of Runx3 expression and methylation with Dnmt1 mRNA expression was analyzed.
The mRNA expression level of Runx3 gene was significantly lower in gastric cancer than that in the matched normal gastric mucosa (0.5740 +/- 0.3580 vs. 1.7250 +/- 0.4080, P < 0.05), and the Runx3 protein expression level in gastric cancer was also significantly lower than that in the matched normal gastric mucosa (P < 0.05). Promoter hypermethylation of Runx3 gene was detected in 50.0% (28/56) of the gastric cancer samples, which resulted in a reduced expression of Runx3 mRNA. It was found that the mRNA expression level of Dnmt1 gene was significantly higher in the gastric cancer tissues with methylated Runx3 gene than that in the ones without. There was a significant correlation of Runx3 gene methylation with increased expression of Dnmtl mRNA (r = 0.64, P < 0.05).
The promoter hypermethylation may be one of the predominant inactivation mechanisms of the runt-related transcription factor 3 gene, and may be associated with carcinogenesis of human gastric cancer. Reduced Runx3 expression in gastric cancer may be partially correlated with a high level of DNA methyltransferase 1.
本研究旨在阐明DNA甲基化在矮小相关转录因子3（Runx3）基因表达中的意义。
采用逆转录聚合酶链反应（RT-PCR）检测70例胃癌患者手术标本中配对的原发性胃癌组织及相应癌旁胃黏膜组织中Runx3 mRNA的表达水平。采用蛋白质免疫印迹法检测Runx3基因的蛋白表达水平。采用甲基化特异性PCR（MSP）检测Runx3基因启动子甲基化状态。此外，采用RT-PCR检测DNA甲基转移酶1（Dnmtl）mRNA的表达。分析Runx3表达及甲基化与Dnmt1 mRNA表达的相关性。
胃癌组织中Runx3基因的mRNA表达水平显著低于配对的正常胃黏膜组织（0.5740±0.3580 vs. 1.7250±0.4080，P<0.05），胃癌组织中Runx3蛋白表达水平也显著低于配对的正常胃黏膜组织（P<0.05）。50.0%（28/56）的胃癌样本检测到Runx3基因启动子高甲基化，导致Runx3 mRNA表达降低。发现Runx3基因甲基化的胃癌组织中Dnmt1基因的mRNA表达水平显著高于未甲基化的组织。Runx3基因甲基化与Dnmtl mRNA表达增加显著相关（r = 0.64，P<0.05）。
启动子高甲基化可能是矮小相关转录因子3基因主要的失活机制之一，可能与人类胃癌的发生有关。胃癌中Runx3表达降低可能部分与高水平的DNA甲基转移酶1有关。
