Epigenetic inactivation of TMS1/ASC in ovarian cancer
Epigenetic inactivation of TMS1/ASC in ovarian cancer
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DOI：
10.1158/1078-0432.ccr-0932-03
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发表时间：
2004-03-15
影响因子：
11.5
通讯作者：
Kudo, R
中科院分区：
文献类型：
--
作者：
Terasawa, K;Sagae, S;Kudo, R
目的：本研究的目的是通过检测原发性卵巢癌和癌细胞系中4个促凋亡基因的DNA甲基化和表达状态，并将这些发现与卵巢癌患者的临床病理学特征相关联，来探讨凋亡途径的表观遗传失活在卵巢癌中的作用。用酚氯仿抽提法从15个卵巢癌细胞系、80个原发性卵巢癌标本和4个正常卵巢标本中提取基因组DNA。DNA的甲基化状态进行了评估，使用组合亚硫酸氢盐限制性分析，基因表达进行了评估，使用逆转录-PCR，和组蛋白乙酰化进行了评估，使用染色质免疫沉淀法。结果：四个促凋亡基因的研究，TMS 1/ASC的表达是不存在的6个卵巢癌细胞系。在不表达TMS 1/ASC的细胞中检测到TMS 1/ASC的5'区域的密集甲基化。用5-氮杂脱氧胞苷处理甲基化的细胞恢复了基因表达，证实了甲基化在沉默基因中的作用。染色质免疫沉淀显示组蛋白去乙酰化在不表达TMS 1/ASC的细胞中，表明组蛋白去乙酰化也参与沉默TMS 1/ASC。80例卵巢癌组织中有15例（19%）检测到TMS 1/ASC异常甲基化，而正常卵巢组织中无异常甲基化。TMS 1/ASC异常甲基化在透明细胞型卵巢癌中的发生率显著高于其他类型的卵巢癌（P < 0.0001）。结论：TMS 1/ASC甲基化介导的沉默通过使肿瘤细胞逃避凋亡而赋予肿瘤细胞生存优势。异常甲基化在人类卵巢肿瘤发生中的作用对于具有透明细胞表型的卵巢癌可能特别重要。
Purpose: The purpose of this work was to explore the role of epigenetic inactivation of apoptotic pathways in ovarian cancer by examining the DNA methylation and expression status of four proapoptotic genes in primary ovarian cancers and cancer cell lines and to correlate those findings with the clinicopathological features of ovarian cancer patients.Experimental Design: Genomic DNA was isolated from 15 ovarian cancer cell lines, 80 primary ovarian cancer specimens, and 4 normal ovary specimens using phenolchloroform extraction. The methylation status of the DNA was evaluated using combined bisulfite restriction analysis, gene expression was evaluated using reverse transcription-PCR, and histone acetylation was evaluated using chromatin immunoprecipitation.Results: Of the four proapoptotic genes studied, expression of TMS1/ASC was absent in six ovarian cancer cell lines. Dense methylation of the 5' region of TMS1/ASC was detected in cells not expressing TMS1/ASC. Treating methylated cells with 5-aza-deoxycytidine restored gene expression, confirming the role of methylation in silencing the gene. Chromatin immunoprecipitation revealed histone to be deacetylated in cells not expressing TMS1/ASC, indicating that histone deacetylation is also involved in silencing TMS1/ASC. Aberrant methylation of TMS1/ASC was detected in 15 of 80 ovarian cancer tissues (19%) but in none of the normal ovary specimens. Aberrant methylation of TMS1/ASC was observed significantly more often in clear cell-type ovarian cancers than in other tumor types (P < 0.0001).Conclusions: Methylation-mediated silencing of TMS1/ASC confers a survival advantage to tumor cells by enabling them to escape apoptosis. The role for aberrant methylation in human ovarian tumorigenesis may be particularly important for ovarian cancers with the clear cell phenotype.