PCDH18 is frequently inactivated by promoter methylation in colorectal cancer.
PCDH18 is frequently inactivated by promoter methylation in colorectal cancer.
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PCDH18 在结直肠癌中经常因启动子甲基化而失活
DOI：
10.1038/s41598-017-03133-w
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发表时间：
2017-06-06
影响因子：
4.6
通讯作者：
Zhang Y
中科院分区：
文献类型：
--
作者：
Zhou D;Tang W;Su G;Cai M;An HX;Zhang Y
利用生物信息学工具发现原钙粘蛋白18（PCDH 18）在结直肠癌（CRC）中优先甲基化和失活。然而，其在肿瘤发生中的生物学作用仍不清楚。在此，我们的目的是阐明其表观遗传调控和CRC的生物学功能。PCDH 18在结直肠癌组织中的甲基化状态显著高于癌旁非肿瘤组织（中位数，15.17% vs.中位数，0.4438%）。PCDH 18在原发性CRC中的表达水平显著低于非癌组织。重要的是，CRC患者游离DNA中PCDH 18的甲基化状态也显著高于健康受试者。PCDH 18在NCM 460细胞中表达，但在100%（4/4）的CRC细胞系中由于启动子甲基化而下调，尽管通过去甲基化处理可以恢复其表达。PCDH 18的过表达抑制CRC细胞活力、集落形成和迁移。同时，siRNA去除PCDH 18后，NCM 460细胞集落形成能力和迁移能力增强，β-catenin核内聚集增加，细胞周期阻滞减少。这些作用与磷酸化GSK-3β和细胞周期蛋白D1的上调以及半胱天冬酶3和p21的下调有关。我们的研究结果表明，PCDH 18是一个假定的肿瘤抑制基因，在大肠癌中具有表观遗传沉默，是大肠癌诊断的潜在生物标志物。
Protocadherin18 (PCDH18) was found to be preferentially methylated and inactivated in colorectal cancer (CRC) using bioinformatics tools. However, its biologic role in tumorgenesis remains unclear. Herein, we aimed to elucidate its epigenetic regulation and biological functions in CRC. The methylation status of PCDH18 was significant higher in CRC tissues than in adjacent non-tumor tissues (median, 15.17% vs. median, 0.4438%). Expression level of PCDH18 was significantly lower in primary CRCs than in nonmalignant tissues. Importantly, methylation status of PCDH18 in cell-free DNA of CRC patients was also significantly higher than in healthy subjects. PCDH18 was readily expressed in NCM460 cells, but downregulated in 100% (4/4) of CRC cell lines by promoter methylation, despite its expression could be restored through demethylation treatment. Overexpression of PCDH18 suppressed CRC cell viability, colony formation and migration. Meanwhile, the depletion of PCDH18 by siRNA in NCM460 cells enhanced the colonogenicity and migration ability and promoted β-catenin nuclear accumulation, whereas it inhibited cell cycle arrest. These effects were associated with upregulation of phospho-GSK-3β and cyclin D1, and downregulation of caspase3 and p21. Our results suggested that PCDH18 was a putative tumor suppressor with epigenetic silencing in CRC and a potential biomarker for CRC diagnosis.