Re-expression of methylation-induced tumor suppressor gene silencing is associated with the state of histone modification in gastric cancer cell lines  

作　　者：Chun-Feng Meng Xin-Jiang Zhu Guo Peng Dong-Qiu Dai 

机构地区：[1]Department of Surgical Oncology, The First Affiliated Hospital,China Medical University, Shenyang 110001, Liaoning Province,China

出　　处：《World Journal of Gastroenterology》2007年第46期6166-6171,共6页世界胃肠病学杂志（英文版）

基　　金：National Natural Science Foundation of China,No.30271477,No.30572162

摘　　要：AIM： To identify the relationship between DNA hyper- methylation and histone modification at a hyperme- thylated, silenced tumor suppressor gene promoter in human gastric cancer cell lines and to elucidate whether alteration of DNA methylation could affect histone modification. METHODS： We used chromatin immunoprecipitation （CHIP） assay to assess the status of histone acetylation and methylation in promoter regions of the p16 and rnutL homolog 1 （MLH1） genes in 2 gastric cancer cell lines, SGC-7901 and MGC-803. We used methylation- specific PCR （MSP） to evaluate the effect of 5-Aza-2＇- deoxycytidine （5-Aza-dC）, trichostatin A （TSA） or their combination treatment on DNA methylation status. We used RT-PCR to determine whether alterations of histone modification status after 5-Aza-dC and TSA treatment are reflected in gene expression. RESULTS： For thep16 and MLH1 genes in two cell lines, silenced loci associated with DNA hypermethylation were characterized by histone H3-K9 hypoacetylation and hypermethylation and histone H3-K4 hypomethylation. Treatment with TSA resulted in moderately increased histone H3-K9 acetylation at the silenced loci with no effect on histone H3-K9 methylation and minimal effects on gene expression. In contrast, treatment with 5-Aza- dC rapidly reduced histone H3-K9 methylation at the silenced loci and resulted in reactivation of the two genes. Combined treatment with 5-Aza-dC and TSA was synergistic in reactivating gene expression at the loci showing DNA hypermethylation. Similarly, histone H3-K4 methylation was not affected alter TSA treatment, andincreased moderately at the silenced loci after 5-Aza-dC treatment. CONCLUSION： Hypermethylation of DNA in promoter CpG islands is related to transcriptional silencing of tumor suppressor genes. Histone H3-K9 methylation in different regions of the promoters studied correlates with DNA methylation status of each gene in gastric cancer cells. However, histone H3-K9 acetylation and H3-K4 methylation inversely correlate 瞄准：识别在 DNA hyper-methylation 之间的关系并且嘘在 hyperme-thylated 的一修正， silenced 肿瘤压制或在人的胃的癌症房间线并且到的基因倡导者阐明 DNA 甲基化的改变是否能影响嘘一修正。方法：我们使用了染色质免疫降水(薄片) 估计地位的试金嘘在 p16 和 mutL 相当或相同的事物的倡导者区域的一乙酰化作用和甲基化 1 (MLH1 ) 在 2 根胃的癌症房间线， SGC-7901 和 MGC-803 的基因。我们使用了 methylation 特定的 PCR (MSP ) 评估 5-Aza-2'-deoxycytidine (5-Aza-dC ) 的效果， trichostatin A (TSA ) 或他们 DNA 甲基化上的联合治疗地位。我们使用了 RT-PCR 决定是否改变嘘在 5-Aza-dC 和 TSA 治疗以后的一修正地位在基因表示被反映。结果：为在二根房间线的 p16 和 MLH1 基因，与 DNA hypermethylation 联系的 silenced 部位被描绘由嘘一 H3-K9 hypoacetylation 和 hypermethylation 并且嘘一 H3-K4 hypomethylation。有 TSA 的治疗导致了中等增加了嘘在没有效果在上的 silenced 部位的一 H3-K9 乙酰化作用嘘基因表示上的一 H3-K9 甲基化和最小的效果。相反，有 5-Aza-dC 的治疗很快减少了嘘在 silenced 部位的一 H3-K9 甲基化并且导致了二基因的复活。有 5-Aza-dC 和 TSA 的联合治疗是在在显示出 DNA hypermethylation 的部位重新激活基因表示的协同的。同样，嘘一 H3-K4 甲基化没在 TSA 处理以后被影响，并且在 5-Aza-dC 处理以后在 silenced 部位中等增加了。结论：在倡导者 CpG 岛的 DNA 的 Hypermethylation 与肿瘤的 transcriptional silencing 有关压制或基因。在倡导者的不同区域的组蛋白 H3-K9 甲基化在胃的癌症房间与每基因的 DNA 甲基化地位学习了相互关联。然而，嘘一 H3-K9 乙酰化作用和 H3-K4 甲基化相反地在胃的癌症房间与每基因的 DNA 甲基化地位相关。DNA 甲基化的改变影响嘘一修正。

关 键 词：Gastric cancer DNA hypermethylation Histone methylation Histone acetylation p16 mutLhomolog 1 5-Aza-2＇-deoxycytidine  Trichostatin A 

分 类 号：R735.2[医药卫生—肿瘤]