Sato Koji, Tomizawa Yoshio, Iijima Hironobu, Saito Ryusei, Ishizuka Tamotsu, Nakajima Takashi, Mori Masatomo
Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Japan.
Oncol Rep. 2006 Jan;15(1):129-35.
The silencing of tumor suppressor genes (TSGs) by aberrant hypermethylation occurs frequently in human cancer. Recently the RUNX3 gene was identified as a TSG inactivated by hypermethylation. We examined RUNX3 expression by reverse transcription-PCR and the methylation status of this gene by methylation specific-PCR in 43 lung cancer cell lines and 120 primary non-small cell lung cancer (NSCLC) tumor samples. RUNX3 expression was absent in 10 (50%) of 20 small cell lung cancer (SCLC) cell lines, 8 (50%) of 16 adenocarcinoma (AdC) cell lines, and 1 (33.3%) of 3 squamous cell carcinoma (SqC) cell lines. The frequency of RUNX3 methylation was significantly higher in AdC (7/16, 43.8%) than SCLC cell lines (1/20, 5%; p=0.032). RUNX3 expression was restored by treatment with 5-aza-2'-deoxycytidine and/or trichostatin-A in AdC cell lines. These results indicated that RUNX3 expression was regulated by aberrant hypermethylation in AdC cell lines. RUNX3 methylation was detected in 30 (25%) of 120 primary NSCLC tumors. RUNX3 methylation was significantly more frequent in non-smokers (16/43, 37.2%) than smokers (12/71, 16.9%; p=0.014), and in patients with AdC (26/72, 36.1%) than in patients with SqC (3/45, 6.7%; p<0.001). These results indicated that silencing of the RUNX3 gene plays an important role in the pathogenesis of lung cancer, and aberrant methylation is an important mechanism of inactivation of the RUNX3 gene in lung AdC.
肿瘤抑制基因（TSGs）因异常高甲基化而沉默在人类癌症中频繁发生。最近，RUNX3基因被鉴定为一个因高甲基化而失活的肿瘤抑制基因。我们通过逆转录聚合酶链反应检测了43个肺癌细胞系和120个原发性非小细胞肺癌（NSCLC）肿瘤样本中RUNX3的表达，并通过甲基化特异性聚合酶链反应检测了该基因的甲基化状态。在20个小细胞肺癌（SCLC）细胞系中的10个（50%）、16个腺癌（AdC）细胞系中的8个（50%）以及3个鳞状细胞癌（SqC）细胞系中的1个（33.3%）中未检测到RUNX3表达。RUNX3甲基化的频率在AdC细胞系（7/16，43.8%）中显著高于SCLC细胞系（1/20，5%；p = 0.032）。在AdC细胞系中，用5-氮杂-2'-脱氧胞苷和/或曲古抑菌素-A处理后，RUNX3表达得以恢复。这些结果表明，在AdC细胞系中，RUNX3表达受异常高甲基化调控。在120个原发性NSCLC肿瘤中的30个（25%）检测到RUNX3甲基化。RUNX3甲基化在非吸烟者（16/43，37.2%）中比吸烟者（12/71，16.9%；p = 0.014）更频繁，在腺癌患者（26/72，36.1%）中比鳞状细胞癌患者（3/45，6.7%；p < 0.001）更频繁。这些结果表明，RUNX3基因的沉默在肺癌发病机制中起重要作用，异常甲基化是肺腺癌中RUNX3基因失活的重要机制。
