Epigenetic inactivation of RUNX3 in microsatellite unstable sporadic colon cancers
Epigenetic inactivation of RUNX3 in microsatellite unstable sporadic colon cancers
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DOI：
10.1002/ijc.20472
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发表时间：
2004-12-10
影响因子：
6.4
通讯作者：
Boland, CR
中科院分区：
文献类型：
--
作者：
Goel, A;Arnold, CN;Boland, CR
Runt 结构域转录因子是 TGF-β 超家族蛋白的重要靶标，在哺乳动物发育中发挥着至关重要的作用。已描述了三种哺乳动物矮小相关基因：RUNX1、RUNX2 和 RUNX3。 RUNX3 已被证明是一种假定的肿瘤抑制基因，位于染色体 Ip36，该区域在结肠癌、胃癌、乳腺癌和卵巢癌中经常出现杂合性丢失事件。由于 TGF-β 信号传导在人类结肠中的重要作用，我们假设 RUNX3 可能作为人类结肠癌和结肠癌衍生细胞系中的关键肿瘤抑制因子。我们检测了 17 种结肠癌细胞系和 91 种散发性结直肠癌中的 RUNX3 表达和 RUNX3 启动子高甲基化频率。通过 RT-PCR 对 RUNX3 转录本进行半定量分析，并通过甲基化特异性 PCR (MSP) 测定研究 RUNX3 启动子的从头甲基化。 91 个信息性肿瘤中的 19 个 (21%) 和 17 个结肠癌细胞系中的 11 个 (65%) 表现出 RUNX3 启动子的高甲基化。有趣的是，RUNX3 启动子高甲基化在表现出高频率微卫星不稳定性 (MSI-H) 的肿瘤中更为常见（MSI-H 为 33%，MSI-L/MSS 肿瘤为 12%；p = 0.012）。 RUNX3 启动子的高甲基化与所有细胞系中 mRNA 转录物的丢失相关。在用去甲基化剂5-aza-2'-脱氧胞苷处理后，SW48和HCT15结肠癌细胞中RUNX3启动子甲基化被逆转，其表达恢复，表明表达丧失是由结肠癌发生中的表观遗传失活引起的。这是首次证明 RUNX3 启动子在散发性结肠癌中频繁发生从头高甲基化。 RUNX3 启动子高甲基化与 MSI-H 结肠癌的显着相关性表明，RUNX3 与 hMLHI 基因一起是 MSI-H 结肠直肠癌进化中的新甲基化靶标。 (C) 2004 Wiley-Liss, Inc.
Runt domain transcription factors are important targets of TGF-beta superfamily proteins and play a crucial role in mammalian development. Three mammalian runt-related genes, RUNX1, RUNX2 and RUNX3, have been described. RUNX3 has been shown to be a putative tumor suppressor gene localized to chromosome Ip36, a region showing frequent loss of heterozygosity events in colon, gastric, breast and ovarian cancers. Because of the important role of TGF-beta signaling in the human colon, we hypothesized that RUNX3 may serve as a key tumor suppressor in human colon cancers and colon cancer-derived cell lines. We examined RUNX3 expression and the frequency of RUNX3 promoter hypermethylation in 17 colon cancer cell lines and 91 sporadic colorectal cancers. Semiquantitative analysis of RUNX3 transcripts was performed by RT-PCR and de novo methylation of the RUNX3 promoter was studied by a methylation-specific PCR (MSP) assay. Nineteen of 91 informative tumors (21%) and 11 of 17 (65%) colon cancer cell lines exhibited hypermethylation of the RUNX3 promoter. Interestingly, RUNX3 promoter hypermethylation was more common in tumors exhibiting high frequency of microsatellite instability (MSI-H) (33% of MSI-H vs. 12% of MSI-L/MSS tumors; p = 0.012). Hypermethylation of the RUNX3 promoter correlated with loss of mRNA transcripts in all cell lines. RUNX3 promoter methylation was reversed and its expression restored in SW48 and HCT15 colon cancer cells after treatment with the demethylating agent 5-aza-2'-deoxycytidine, indicating that loss of expression is caused by epigenetic inactivation in colon carcinogenesis. This is the first demonstration of frequent de novo hypermethylation of the RUNX3 promoter in sporadic colon cancers. The significant association of RUNX3 promoter hypermethylation with MSI-H colon cancers suggests that RUNX3 is a novel target of methylation, along with the hMLHI gene, in the evolution of MSI-H colorectal cancers. (C) 2004 Wiley-Liss, Inc.