Department of Surgery, Saga University Faculty of Medicine, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Ann Surg Oncol. 2010 Apr;17(4):1177-86. doi: 10.1245/s10434-009-0815-8. Epub 2009 Dec 3.
This study was designed to determine whether gene methylation is a novel diagnostic marker for micrometastasis to the lymph nodes (LNs) in gastric cancer.
The gene methylation of CHFR, p16, RUNX3, E-cadherin, MGMT, hMLH1, and ABCG2 genes were analyzed in 49 primary gastric cancer tissues, corresponding to noncancerous tissues and matched LNs by quantitative methylation-specific PCR (q-MSP).
CHFR, RUNX3, MGMT, and hMLH1 were more frequently methylated in primary cancer compared with the noncancerous mucosa. Further analyses investigated whether the methylation of the four cancer-specific genes was preserved in LN tissues using the 29 control cases, in which LN metastasis had been histologically confirmed. The methylation of both lesions (M/M pattern) in at least one gene, which was judged to be positive for cancer cells in LNs, was observed in 25 of 29 cases (86%). Quantitative RT-PCR (qRT-PCR) of CEA, CK19, and CK20 mRNA was conducted using the same samples. The mRNA expression of at least one of the three genes was observed in 100% of the specimens. The results of the control analysis were used to attempt to predict micrometastasis by q-MSP and qRT-PCR in the 20 test cases without histological LN metastasis. Six cases (30%) showed the M/M pattern in at least one of the four genes. Three of 20 cases (15%) exhibited both the M/M pattern and positive mRNA.
The methylation analysis revealed the clinical feasibility of detecting occult neoplastic cells in the regional LNs.
本研究旨在确定基因甲基化是否是胃癌淋巴结微转移的新型诊断标志物。
通过定量甲基化特异性 PCR（q-MSP）分析 49 例原发性胃癌组织及其对应的非癌组织和匹配的淋巴结中 CHFR、p16、RUNX3、E-钙黏蛋白、MGMT、hMLH1 和 ABCG2 基因的基因甲基化。
与非癌性黏膜相比，CHFR、RUNX3、MGMT 和 hMLH1 在原发性癌症中更频繁地发生甲基化。进一步的分析使用 29 例经组织学证实有淋巴结转移的对照病例，研究了这四个癌症特异性基因的甲基化是否在淋巴结组织中得以保留。在至少一个基因中（M/M 模式），即判断为淋巴结中癌细胞阳性的两种病变的甲基化，在 29 例中的 25 例（86%）中观察到。使用相同的样本对 CEA、CK19 和 CK20 mRNA 进行了定量 RT-PCR（qRT-PCR）。在 100%的标本中观察到至少一种三种基因之一的 mRNA 表达。对照分析的结果用于尝试通过 q-MSP 和 qRT-PCR 在 20 例无组织学淋巴结转移的测试病例中预测微转移。在至少一个基因中显示 M/M 模式的有 6 例（30%）。在 20 例病例中，有 3 例（15%）同时出现 M/M 模式和阳性 mRNA。
甲基化分析显示了在局部淋巴结中检测隐匿性肿瘤细胞的临床可行性。
