散发性生长激素瘤（PitNETs）通过促进生长激素分泌成为肢端肥大的主要原因。就组织病理学和分子特征而言，这些肿瘤在某种程度上是异质的。我们之前的转录组学研究显示了三种不同的分子亚型。本研究的目的是调查生长激素瘤亚型间的DNA甲基化模式差异以及其在基因表达中的作用。我们使用EPIC微阵列对48个生长激素瘤进行全基因组DNA甲基化研究，并通过RNAseq评估基因表达。利用亚硫酸盐测序和qRT-PCR验证了DNA甲基化和基因表达结果。基于甲基化数据对肿瘤样本进行聚类分析可以反映出转录组相关的分类情况。亚型1的肿瘤细胞颗粒密集且不具有GNAS突变，其特点是NR5A1（SF-1）和GIPR的高表达。这两个基因的表达与基因体和启动子的特定甲基化相关。相较于其它肿瘤，该亚型的5'基因区域和CpG岛的甲基化水平较低。亚型2的生长激素瘤细胞颗粒密集，并且常常发生GNAS突变，而亚型3主要是细胞颗粒较稀疏。甲基化/表达分析显示，位于差异甲基化区域的约50%基因是肿瘤亚型间差异表达的基因。相关分析发现DNA甲基化调控的基因包括CDKN1B、CCND2、EBF3、CDH4、CDH12、MGMT、STAT5A、PLXND1、PTPRE、MMP16以及编码离子通道和神经元导向因子的基因。DNA甲基化分析证实了生长激素瘤的三种分子亚型的存在。亚型1肿瘤中NR5A1和GIPR的高表达与这两个基因的特定甲基化相关。 S. Karger AG，巴塞尔。

Growth hormone secretion by sporadic somatotroph neuroendocrine pituitary tumors (PitNETs) is major cause of acromegaly. These tumors are relatively heterogenous in terms of histopathological and molecular features. Our previous transcriptomic profiling of somatotroph tumors revealed three distinct molecular subtypes. This study was aimed to investigate difference in DNA methylation pattern in subtypes of somatotroph PitNETs and its role in distinctive gene expression.Genome-wide DNA methylation was investigated in 48 somatotroph PitNETs with EPIC microarrays. Gene expression was assessed with RNAseq. Bisulfite pyrosequencing and qRT-PCR were used for verifying results of DNA methylation and gene expression.Clustering tumor samples based on methylation data reflected the transcriptome-related classification. Subtype 1 tumors are densely granulated without GNAS mutation, characterized by high expression of NR5A1 (SF-1) and GIPR. The expression of both genes is correlated with specific methylation of gene body and promoter. This subtype has lower methylation level of 5' gene regions and CpG islands than the remaining tumors. Subtype 2 PitNETs are densely granulated, frequently GNAS-mutated while those in subtype 3 are mainly sparsely granulated. Methylation/expression analysis indicates that ~50% genes located in differentially methylated regions are those differentially expressed between tumor subtypes. Correlation analysis revealed DNA methylation-controlled genes including CDKN1B, CCND2, EBF3, CDH4, CDH12, MGMT, STAT5A, PLXND1, PTPRE, MMP16 and genes encoding ion channels and semaphorins.DNA methylation profiling confirmed the existence of three molecular subtypes of somatotroph PitNETs. High expression of NR5A1 and GIPR in subtype 1 tumors is correlated with specific methylation of both genes.S. Karger AG, Basel.