Intermediate filament dynamics and breast cancer: Aberrant promoter methylation of the Synemin gene is associated with early tumor relapse
Intermediate filament dynamics and breast cancer: Aberrant promoter methylation of the Synemin gene is associated with early tumor relapse
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DOI：
10.1038/onc.2010.229
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发表时间：
2010-08-01
期刊：
影响因子：
8
通讯作者：
Dahl, E.
中科院分区：
文献类型：
--
作者：
Noetzel, E.;Rose, M.;Dahl, E.
SYNM是一种IV型中间丝，最近被发现与LIM结构域蛋白Zysin相互作用，从而可能调节细胞黏附和细胞运动。由于与癌症发展相关的多种潜在功能，我们启动了一项研究，以破译SYNM在人类良性乳腺组织和乳腺癌中的表达和调控。斑点杂交阵列分析显示，与正常组织相比，86%(n=100，P<；0.001)的乳腺癌组织中SYNM基因表达显著下调，实时定量聚合酶链式反应分析(n=36，P<；0.0001)证实了这一结果。免疫组织化学分析显示SYNM蛋白在正常乳腺组织中大量表达，而57%的乳腺癌组织中SYNM蛋白表达缺失(n=37，P<；0.001)。接下来，我们分析了SYNM启动子的甲基化，以阐明SYNM基因是否可以通过表观遗传学手段沉默。事实上，甲基化特异性的聚合酶链式反应分析显示，在27%(n=195)的乳腺癌中存在肿瘤特异性的SYNM启动子甲基化。正如预期的那样，SYNM启动子甲基化与SYNM表达缺失密切相关(P<；0.0001)。焦磷酸测序对SYNM启动子的深入分析表明，调控基因转录的DNA元件发生了广泛的CpG甲基化。用5-氮杂-2-脱氧胞苷去甲基化处理SYNM甲基化的乳腺癌细胞株，明显重建了SYNM的表达。对患者队列的统计分析显示，SYNM启动子甲基化与不良无复发生存率密切相关(风险比=2.941，P=0.0282)。此外，SYNM甲基化与淋巴结转移(P=0.0177)和进展期肿瘤分级(P=0.0275)呈正相关，提示SYNM甲基化与乳腺癌的侵袭性有关。这是关于SYNM基因在癌症实体中的表观遗传调控的第一次研究。我们首次暗示，SYNM可能代表了一种新的可能的乳腺癌抑制基因，该基因容易发生表观遗传沉默。SYNM启动子甲基化可能成为乳腺癌患者肿瘤复发风险分层的有用预测生物标记物。Oncogene(2010)29,4814-4825；doi：10.1038/onc.2010.229；2010年6月14日在线发布
Synemin (SYNM) is a type IV intermediate filament that has recently been shown to interact with the LIM domain protein zyxin, thereby possibly modulating cell adhesion and cell motility. Owing to this multiplicity of potential functions relevant to cancer development, we initiated a study to decipher SYNM expression and regulation in benign human breast tissue and breast cancer. Dot blot array analysis showed significant SYNM mRNA downregulation in 86% (n = 100, P < 0.001) of breast cancers compared with their normal tissue counterparts, a result that was confirmed by real-time PCR analysis (n = 36, P < 0.0001). Immunohistochemistry analysis showed abundant SYNM protein expression in healthy myoepithelial breast cells, whereas SYNM expression loss was evident in 57% (n = 37, P < 0.001) of breast cancer specimens. Next, we analyzed methylation of the SYNM promoter to clarify whether the SYNM gene can be silenced by epigenetic means. Indeed, methylation-specific PCR analysis showed tumor-specific SYNM promoter methylation in 27% (n = 195) of breast cancers. As expected, SYNM promoter methylation was tightly associated (P < 0.0001) with SYNM expression loss. In-depth analysis of the SYNM promoter by pyrosequencing showed extensive CpG methylation of DNA elements supposed to regulate gene transcription. Demethylating treatment of SYNM methylated breast cancer cell lines with 5-aza-2-deoxycytidine clearly reestablished the SYNM expression. Statistical analysis of the patient cohort showed a close association between SYNM promoter methylation and unfavorable recurrence-free survival (hazard ratio = 2.941, P = 0.0282). Furthermore, SYNM methylation positively correlated with lymph node metastases (P = 0.0177) and advanced tumor grade (P = 0.0275), suggesting that SYNM methylation is associated with aggressive forms of breast cancer. This is the first study on the epigenetic regulation of the SYNM gene in a cancer entity. We provide first hints that SYNM could represent a novel putative breast tumor suppressor gene that is prone to epigenetic silencing. SYNM promoter methylation may become a useful predictive biomarker to stratify breast cancer patients' risk for tumor relapse. Oncogene (2010) 29, 4814-4825; doi:10.1038/onc.2010.229; published online 14 June 2010