Department of Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-Ku, Tokyo, 160-8582, Japan.
Fundamental Innovative Oncology Core Center, National Cancer Center Research Institute, Tokyo, 104-0045, Japan.
J Cancer Res Clin Oncol. 2023 Jul;149(8):5109-5125. doi: 10.1007/s00432-022-04445-9. Epub 2022 Nov 8.
This study was performed to identify the DNA methylation profiles underlying the clinicopathological diversity of non-alcoholic steatohepatitis (NASH)-related hepatocellular carcinomas (HCCs). METHODS: Genome-wide DNA methylation analysis of 88 liver tissue samples was performed using the Infinium assay.
Principal component analysis revealed that distinct DNA methylation profiles differing from such profiles in normal control liver tissue had already been established in non-cancerous liver tissue showing NASH, which is considered to be a precancerous condition. Hierarchical clustering separated 26 NASH-related HCCs into Cluster I (n = 8) and Cluster II (n = 18). Such epigenetic clustering was significantly correlated with histopathological diversity, i.e. poorer tumor differentiation, tumor steatosis and development of a scirrhous HCC component. Significant differences in DNA methylation levels between the two clusters were accumulated in molecular pathways participating in cell adhesion and cytoskeletal remodeling, as well as cell proliferation and apoptosis. Among tumor-related genes characterizing Clusters I and II, differences in the levels of DNA methylation and mRNA expression for the SPHK1, INHBA, LTB and PDE3B genes were correlated with poorer tumor differentiation. 5-Aza-2'-deoxycytidine treatment of HCC cells revealed epigenetic regulation of the SPHK1 and LTB genes. Knockdown experiments showed that SPHK1 promotes cell proliferation, represses apoptosis and enhances migration, whereas LTB enhances migration of HCC cells. DNA hypomethylation resulting in increased expression of SPHK1 and LTB in poorly differentiated HCCs may underlie the aggressive phenotype of such HCCs.
These data indicate that DNA methylation profiles may determine the clinicopathological heterogeneity of NASH-related HCCs via alterations of tumor-related gene expression.
本研究旨在确定非酒精性脂肪性肝炎（NASH）相关肝细胞癌（HCC）临床病理多样性的 DNA 甲基化谱。
采用 Infinium 检测法对 88 个肝组织样本进行全基因组 DNA 甲基化分析。
主成分分析显示，在被认为是癌前病变的 NASH 非癌性肝组织中，已经建立了与正常对照肝组织不同的独特 DNA 甲基化谱。层次聚类将 26 例 NASH 相关 HCC 分为 I 群（n=8）和 II 群（n=18）。这种表观遗传聚类与组织病理学多样性显著相关，即肿瘤分化较差、肿瘤脂肪变性和形成硬癌成分。两个聚类之间的 DNA 甲基化水平存在显著差异，这些差异积累在参与细胞黏附和细胞骨架重塑以及细胞增殖和凋亡的分子途径中。在代表 I 群和 II 群的肿瘤相关基因中，SPHK1、INHBA、LTB 和 PDE3B 基因的 DNA 甲基化水平和 mRNA 表达水平的差异与肿瘤分化较差相关。5-Aza-2'-脱氧胞苷处理 HCC 细胞显示 SPHK1 和 LTB 基因的表观遗传调控。敲低实验表明，SPHK1 促进细胞增殖、抑制细胞凋亡和增强迁移，而 LTB 增强 HCC 细胞的迁移。低甲基化导致 SPHK1 和 LTB 在低分化 HCC 中表达增加，可能是此类 HCC 侵袭性表型的基础。
这些数据表明，DNA 甲基化谱可能通过改变肿瘤相关基因的表达来决定 NASH 相关 HCC 的临床病理异质性。
