Hereditary Endocrine Cancer Group, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
Department of Pathology, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, the Netherlands.
Clin Cancer Res. 2015 Jul 1;21(13):3020-30. doi: 10.1158/1078-0432.CCR-14-2804. Epub 2015 Mar 30.
Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors, associated with highly variable postoperative evolution. The scarcity of reliable PPGL prognostic markers continues to complicate patient management. In this study, we explored genome-wide DNA methylation patterns in the context of PPGL malignancy to identify novel prognostic markers.
We retrospectively investigated DNA methylation patterns in PPGL with and without metastases using high-throughput DNA methylation profiling data (Illumina 27K) from two large, well-characterized discovery (n = 123; 24 metastatic) and primary validation (n = 154; 24 metastatic) series. Additional validation of candidate CpGs was performed by bisulfite pyrosequencing in a second independent set of 33 paraffin-embedded PPGLs (19 metastatic).
Of the initial 86 candidate CpGs, we successfully replicated 52 (47 genes), associated with metastatic PPGL. Of these, 48 CpGs showed significant associations with time to progression even after correcting for SDHB genotype, suggesting their value as prognostic markers independent of genetic background. Hypermethylation of RDBP (negative elongation factor complex member E) in metastatic tumors was further validated by bisulfite pyrosequencing [Δβmetastatic-benign = 0.29, P = 0.003; HR, 1.4; 95% confidence interval (CI), 1.1-2.0; P = 0.018] and may alter transcriptional networks involving (RERG, GPX3, and PDZK1) apoptosis, invasion, and maintenance of DNA integrity.
This is the first large-scale study of DNA methylation in metastatic PPGL that identifies and validates prognostic markers, which could be used for stratifying patients according to risk of developing metastasis. Of the three CpGs selected for further validation, one (RDBP) was clearly confirmed and could be used for stratifying patients according to the risk of developing metastases.
嗜铬细胞瘤和副神经节瘤（PPGL）是罕见的神经内分泌肿瘤，其术后演变具有高度的可变性。缺乏可靠的 PPGL 预后标志物仍然使患者的管理变得复杂。在这项研究中，我们探讨了 PPGL 恶性肿瘤的全基因组 DNA 甲基化模式，以确定新的预后标志物。
我们使用来自两个大型、特征明确的发现（n=123；24 例转移）和主要验证（n=154；24 例转移）系列的高通量 DNA 甲基化分析数据（Illumina 27K），回顾性地研究了有和无转移的 PPGL 的 DNA 甲基化模式。在第二个独立的 33 例石蜡包埋的 PPGL 样本（19 例转移）中，通过亚硫酸氢盐焦磷酸测序对候选 CpG 进行了额外的验证。
在最初的 86 个候选 CpG 中，我们成功复制了 52 个（47 个基因）与转移性 PPGL 相关的 CpG。其中，48 个 CpG 即使在校正了 SDHB 基因型后，仍与疾病进展时间显著相关，表明它们作为独立于遗传背景的预后标志物的价值。在转移性肿瘤中，RDBP（负延伸因子复合物成员 E）的高甲基化通过亚硫酸氢盐焦磷酸测序进一步得到验证[Δβmetastatic-benign=0.29，P=0.003；HR，1.4；95%置信区间（CI），1.1-2.0；P=0.018]，并且可能改变涉及细胞凋亡、侵袭和 DNA 完整性维持的转录网络（RERG、GPX3 和 PDZK1）。
这是对转移性 PPGL 进行的最大规模的 DNA 甲基化研究，该研究确定并验证了预后标志物，可用于根据转移发生风险对患者进行分层。在进一步验证中选择的三个 CpG 中，有一个（RDBP）得到了明确的确认，可用于根据转移风险对患者进行分层。
