Epigenetic inactivation of paired box gene 5, a novel tumor suppressor gene, through direct upregulation of p53 is associated with prognosis in gastric cancer patients
Epigenetic inactivation of paired box gene 5, a novel tumor suppressor gene, through direct upregulation of p53 is associated with prognosis in gastric cancer patients
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DOI：
10.1038/onc.2011.511
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发表时间：
2012-07-01
期刊：
影响因子：
8
通讯作者：
Yu, J.
中科院分区：
文献类型：
--
作者：
Li, X.;Cheung, K. F.;Yu, J.
利用全基因组甲基化筛选，我们确定了配对盒基因5（PAX 5）参与人类癌症的发展。然而，PAX 5在胃癌（GC）发展中的功能在很大程度上尚不清楚。本文分析了其表观遗传失活、生物学功能及其在胃癌中的临床应用。PAX 5在八个GC细胞系中的七个中沉默。与邻近的非癌组织相比，在成对的胃肿瘤中也检测到显著的下调。PAX 5的下调与启动子的高甲基化状态密切相关，并且可以通过去甲基化治疗来恢复。PAX 5在沉默的胃癌细胞系（AGS和BGC 823）中的异位表达抑制集落形成和细胞活力，阻滞细胞周期，诱导凋亡，抑制细胞迁移和侵袭，并抑制裸鼠成瘤性。与PAX 5在体外诱导凋亡一致，末端脱氧核苷酸转移酶介导的dUTP-地高辛缺口末端标记（TUNEL）染色显示，与载体对照肿瘤相比，PAX 5表达肿瘤中的凋亡细胞显著增强。另一方面，通过PAX 5-短发夹RNA敲低PAX 5增加细胞活力和增殖。PAX 5的抗肿瘤功能是通过上调肿瘤蛋白53（p53）、p21、BCL 2相关X蛋白、转移抑制因子1和金属蛋白酶组织抑制因子1的下游靶点，以及下调BCL 2、细胞周期蛋白D1、间充质-上皮转化因子（MET）和基质金属蛋白酶1来介导的。免疫沉淀实验表明PAX 5与p53和MET的启动子直接结合。此外，PAX 5基因甲基化在原发性胃癌中的检出率为77%（144/187），而在正常胃组织中的检出率为10.5%（2/19）（P
Using genome-wide methylation screening, we identified that paired box gene 5 (PAX5) is involved in human cancer development. However, the function of PAX5 in gastric cancer (GC) development is largely unclear. We analyzed its epigenetic inactivation, biological functions and clinical application in GC. PAX5 was silenced in seven out of eight GC cell lines. A significant downregulation was also detected in paired gastric tumors compared with adjacent non-cancerous tissues. The downregulation of PAX5 was closely linked to the promoter hypermethylation status and could be restored with demethylation treatment. Ectopic expression of PAX5 in silenced GC cell lines (AGS and BGC823) inhibited colony formation and cell viability, arrested cell cycle, induced apoptosis, suppressed cell migration and invasion and repressed tumorigenicity in nude mice. Consistent with the induction of apoptosis by PAX5 in vitro, terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) staining showed significantly enhanced apoptotic cells in PAX5-expressed tumors compared with the vector control tumors. On the other hand, knockdown of PAX5 by PAX5-short hairpin RNA increased the cell viability and proliferation. The anti-tumorigenic function of PAX5 was revealed to be mediated by upregulating downstream targets of tumor protein 53 (p53), p21, BCL2-associated X protein, metastasis suppressor 1 and tissue inhibitors of metalloproteinase 1, and downregulating BCL2, cyclin D1, mesenchymal-epithelial transition factor (MET) and matrix metalloproteinase 1. Immunoprecipitation assay demonstrated that PAX5 directly bound to the promoters of p53 and MET. Moreover, PAX5 hypermethylation was detected in 77% (144 of 187) of primary GCs compared with 10.5% (2/19) of normal gastric tissues (P