Hirshberg Laboratories for Pancreatic Cancer Research, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Pancreas. 2010 Jul;39(5):675-9. doi: 10.1097/MPA.0b013e3181c8b476.
N-myc downstream-regulated gene 1 (NDRG1), important in tumor growth and metastasis, has recently gained interest as a potential therapeutic target. Loss of NDRG1 expression is generally associated with poor clinical outcome in pancreatic cancer (PaCa) patients. As the NDRG1 gene possesses a large promoter CpG island, we sought to determine whether its repression is epigenetically mediated in PaCa cells.
Pancreatic cancer cells were treated with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor trichostatin A. Promoter methylation was assessed by genomic bisulfite sequencing and by combined bisulfite restriction analyses.
Treatment with 5-aza-2'-deoxycytidine and trichostatin A enhanced NDRG1 protein expression, implicating epigenetic regulation of NDRG1. However, there was no significant DNA methylation of the NDRG1 promoter CpG island, as determined by genomic bisulfite sequencing of HPAF-II cells. We further confirmed the lack of promoter methylation in 6 PaCa cell lines by combined bisulfite restriction analyses.
These findings indicate that NDRG1 gene reactivation in PaCa cell lines by pharmacologic reversal of DNA methylation and histone deacetylation occurs via an indirect mechanism. This may occur via the altered expression of genes involved in the regulation of NDRG1 transcription or NDRG1 protein stability in PaCa cells.
N- myc 下游调节基因 1（NDRG1）在肿瘤生长和转移中具有重要作用，最近作为一种潜在的治疗靶点引起了关注。NDRG1 表达的缺失通常与胰腺癌（PaCa）患者的不良临床预后相关。由于 NDRG1 基因具有较大的启动子 CpG 岛，我们试图确定其在 PaCa 细胞中是否受到表观遗传调控。
用 DNA 甲基转移酶抑制剂 5-氮杂-2'-脱氧胞苷和组蛋白去乙酰化酶抑制剂曲古抑菌素 A 处理胰腺癌细胞。通过基因组亚硫酸氢盐测序和联合亚硫酸氢盐限制性分析评估启动子甲基化。
5-氮杂-2'-脱氧胞苷和曲古抑菌素 A 的处理增强了 NDRG1 蛋白的表达，提示 NDRG1 的表达受到表观遗传调控。然而，通过 HPAF-II 细胞的基因组亚硫酸氢盐测序，并未发现 NDRG1 启动子 CpG 岛的显著 DNA 甲基化。我们通过联合亚硫酸氢盐限制性分析进一步证实了 6 种 PaCa 细胞系中不存在启动子甲基化。
这些发现表明，通过药物逆转 DNA 甲基化和组蛋白去乙酰化可使 PaCa 细胞系中 NDRG1 基因重新激活，其机制为间接机制。这可能通过调节 NDRG1 转录或 NDRG1 蛋白在 PaCa 细胞中的稳定性的相关基因的表达改变而发生。
