Sato Norihiro, Fukushima Noriyoshi, Chang Rubens, Matsubayashi Hiroyuki, Goggins Michael
Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA.
Gastroenterology. 2006 Feb;130(2):548-65. doi: 10.1053/j.gastro.2005.11.008.
BACKGROUND & AIMS: Recently described genome-wide approaches robustly detect many candidate genes that are regulated by DNA methylation, but many of these genes do not represent important targets for functional inactivation. Here we used a microarray-based strategy to identify biologically relevant genes associated with epigenetic silencing in pancreatic cancer.
We compared information from differential gene expression analysis with the transcriptional responses to epigenetic modifiers.
Using this approach, we identified 7 novel targets for aberrant methylation in pancreatic cancer. One of the genes identified, RELN (Reelin), a key regulator of neuronal migration, is frequently silenced in pancreatic cancers, as are several of its downstream mediators. Importantly, small interfering RNA-mediated knockdown of RELN in pancreatic cancer cells that retain RELN expression resulted in greatly enhanced cell motility, invasiveness, and colony-forming ability. Increased cell motility was also induced by knockdown of downstream components of the RELN pathway, including ApoER2, VLDLR, and DAB1. Treatment of pancreatic cancer cells with histone deacetylase inhibitors, valproic acid and suberoylanilide hydroxamic acid, restored the expression of RELN and DAB1 and markedly inhibited their migration.
The high prevalence of the silencing of RELN pathway components and its reversal by histone deacetylase inhibitors suggest the importance of this pathway as a diagnostic and therapeutic target for pancreatic cancer.
最近描述的全基因组方法能够可靠地检测出许多受DNA甲基化调控的候选基因，但其中许多基因并非功能失活的重要靶点。在此，我们采用基于微阵列的策略来鉴定与胰腺癌表观遗传沉默相关的生物学相关基因。
我们将差异基因表达分析的信息与对表观遗传修饰剂的转录反应进行了比较。
通过这种方法，我们在胰腺癌中鉴定出7个异常甲基化的新靶点。其中一个被鉴定的基因RELN（Reelin）是神经元迁移的关键调节因子，在胰腺癌中经常沉默，其几个下游介质也是如此。重要的是，在保留RELN表达的胰腺癌细胞中，小干扰RNA介导的RELN敲低导致细胞运动性、侵袭性和集落形成能力大大增强。敲低RELN途径的下游成分，包括载脂蛋白E受体2（ApoER2）、极低密度脂蛋白受体（VLDLR）和Disabled-1（DAB1），也能诱导细胞运动性增加。用组蛋白去乙酰化酶抑制剂丙戊酸和辛二酰苯胺异羟肟酸处理胰腺癌细胞，可恢复RELN和DAB1的表达，并显著抑制它们的迁移。
RELN途径成分沉默的高发生率及其被组蛋白去乙酰化酶抑制剂逆转，表明该途径作为胰腺癌诊断和治疗靶点的重要性。
