Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 1095 Jiefang Road, Wuhan, 430074, Hubei Province, China.
Department of General Surgery, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, China.
BMC Cancer. 2022 Nov 11;22(1):1166. doi: 10.1186/s12885-022-10279-y.
Intrahepatic cholangiocarcinoma (ICC), originating from the bile ducts, is the second most common primary liver malignancy, and its incidence has recently increased. H2A.Z, a highly conserved H2A variant, is emerging as a key regulatory molecule in cancer. However, its underlying mechanism of action in ICC cells remains unclear. METHODS: Here, we examined the expression of H2A.Z and SFRP1 in normal intrahepatic cholangiocytes, ICC cell lines, ICC tissue microarrays, and fresh specimens. The correlations between H2A.Z or SFRP1 expression and clinical features were analysed. The overall survival rate was analysed based on H2A.Z and SFRP1 expression. Immunoprecipitation was used to analyse the recruitment of KDM1A, and ChIP sequencing and BSP were used to analyse the enrichment of methylation-related molecules such as H3K4me1 and H3K4me2 in the SFRP1 promoter and reveal the underlying mechanisms. Knockdown and rescue experiments were used to determine the potential mechanism by which H2A.Z and SFRP1 promote tumorigenesis in vitro.
We showed that upregulation of H2A.Z expression is linked to downregulation of SFRP1 expression in ICC tissues and poor overall survival in patients with ICC. H2A.Z interacted with KDM1A in the nucleus to bind to the -151 ~ -136 bp region upstream of the SFRP1 promoter to increase its demethylation in ICC cells. Functionally, H2A.Z silencing inhibited the proliferation and invasion of ICC cells, and these effects were mitigated by SFRP1 silencing in ICC cells.
Our findings reveal that H2A.Z inhibits SFRP1 expression through chromatin modification in the context of ICC by forming a complex with KDM1A in the nucleus.
肝内胆管癌（ICC）起源于胆管，是第二大常见的原发性肝脏恶性肿瘤，其发病率最近有所增加。H2A.Z 是一种高度保守的 H2A 变体，作为癌症的关键调节分子而崭露头角。然而，其在 ICC 细胞中的作用机制尚不清楚。
在这里，我们检查了 H2A.Z 和 SFRP1 在正常肝内胆管细胞、ICC 细胞系、ICC 组织微阵列和新鲜标本中的表达。分析了 H2A.Z 或 SFRP1 表达与临床特征之间的相关性。根据 H2A.Z 和 SFRP1 的表达分析总生存率。免疫沉淀用于分析 KDM1A 的募集，ChIP 测序和 BSP 用于分析 SFRP1 启动子中与甲基化相关的分子（如 H3K4me1 和 H3K4me2）的富集，并揭示潜在的机制。通过敲低和挽救实验来确定 H2A.Z 和 SFRP1 在体外促进肿瘤发生的潜在机制。
我们表明，在 ICC 组织中 H2A.Z 表达的上调与 SFRP1 表达的下调相关，并且 ICC 患者的总体生存率较差。H2A.Z 在核内与 KDM1A 相互作用，结合 SFRP1 启动子上游的-151~-136bp 区域，增加其在 ICC 细胞中的去甲基化。功能上，H2A.Z 沉默抑制了 ICC 细胞的增殖和侵袭，而在 ICC 细胞中 SFRP1 沉默减轻了这些作用。
我们的研究结果表明，H2A.Z 通过与核内 KDM1A 形成复合物，在 ICC 中通过染色质修饰抑制 SFRP1 的表达。
