ITIH5 mediates epigenetic reprogramming of breast cancer cells.
ITIH5 mediates epigenetic reprogramming of breast cancer cells.
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DOI：
10.1186/s12943-017-0610-2
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发表时间：
2017-02-23
期刊：
影响因子：
37.3
通讯作者：
Dahl E
中科院分区：
文献类型：
--
作者：
Rose M;Kloten V;Noetzel E;Gola L;Ehling J;Heide T;Meurer SK;Gaiko-Shcherbak A;Sechi AS;Huth S;Weiskirchen R;Klaas O;Antonopoulos W;Lin Q;Wagner W;Veeck J;Gremse F;Steitz J;Knüchel R;Dahl E
众所周知，细胞外基质（ECM）可以维持上皮完整性。在致癌过程中，ECM 降解通过控制迁移和分化（包括癌症干细胞 (CSC) 特征）来触发转移。 ECM 调节剂间 α-胰蛋白酶抑制剂重链家族成员 5 (ITIH5) 最近被确定为可能参与损害乳腺癌进展的肿瘤抑制因子，但其功能背后的分子机制仍不清楚。 使用公共 TCGA 门户分析 ITIH5 表达。基于T47D和MDA-MB-231细胞系建立ITIH5过表达单细胞克隆。体外研究了肿瘤细胞的集落形成、生长、凋亡、迁移、基质粘附、牵引力分析和极化。通过生成转移小鼠模型来分析肿瘤起始特征。为了确定 ITIH5 影响的途径，我们利用全基因组基因表达和 DNA 甲基化谱。针对 ITIH5 下游调节基因 DAPK1 的 RNA 干扰用于确认功能参与。 ITIH5 缺失在乳腺癌亚型中明显，且预后不良，如基底型肿瘤。在功能上，两种细胞系中 ITIH5 重新表达后，细胞和集落形成均受到损害。在转移小鼠模型中，表达 ITIH5 的 MDA-MB-231 细胞几乎完全无法引发肺转移。在这些转移细胞中，ITIH5 调节细胞基质粘附动力学并改变生物力学线索。在表达 ITIH5 的克隆中，整合素受体的谱向 β1-整合素转变，伴随着 Rac1 减少和 RhoA 活性增加，同时细胞极化和单细胞迁移受损。相反，ITIH5 的表达触发了上皮样细胞簇的形成，并经历了表观遗传重编程。可能标记有 H3K4 和/或 H3K27 甲基化的 214 个启动子区域由于 ITIH5 表达最终导致肿瘤抑制因子 DAPK1 的重新表达而显示出高甲基化或低甲基化 DNA 构型。反过来，在表达 ITIH5 的 MDA-MB-231 单细胞克隆中，RNAi 介导的 DAPK1 敲低明显恢复了细胞运动性。我们的结果提供证据表明，ITIH5 通过影响已知肿瘤抑制基因（如 DAPK1）的全局表观遗传变化，触发具有已知干 CSC 特性的乳腺癌细胞重编程为上皮样表型。因此，ITIH5可能代表乳腺上皮组织中的ECM调节剂，介导对肿瘤起始癌细胞特征的抑制，而肿瘤起始癌细胞特征被认为是导致乳腺癌转移的原因。本文的在线版本 (doi:10.1186/s12943-017-0610-2) 包含补充材料，可供授权用户使用。
Extracellular matrix (ECM) is known to maintain epithelial integrity. In carcinogenesis ECM degradation triggers metastasis by controlling migration and differentiation including cancer stem cell (CSC) characteristics. The ECM-modulator inter- α-trypsin inhibitor heavy chain family member five (ITIH5) was recently identified as tumor suppressor potentially involved in impairing breast cancer progression but molecular mechanisms underlying its function are still elusive. ITIH5 expression was analyzed using the public TCGA portal. ITIH5-overexpressing single-cell clones were established based on T47D and MDA-MB-231 cell lines. Colony formation, growth, apoptosis, migration, matrix adhesion, traction force analyses and polarization of tumor cells were studied in vitro. Tumor-initiating characteristics were analyzed by generating a metastasis mouse model. To identify ITIH5-affected pathways we utilized genome wide gene expression and DNA methylation profiles. RNA-interference targeting the ITIH5-downstream regulated gene DAPK1 was used to confirm functional involvement. ITIH5 loss was pronounced in breast cancer subtypes with unfavorable prognosis like basal-type tumors. Functionally, cell and colony formation was impaired after ITIH5 re-expression in both cell lines. In a metastasis mouse model, ITIH5 expressing MDA-MB-231 cells almost completely failed to initiate lung metastases. In these metastatic cells ITIH5 modulated cell-matrix adhesion dynamics and altered biomechanical cues. The profile of integrin receptors was shifted towards β1-integrin accompanied by decreased Rac1 and increased RhoA activity in ITIH5-expressing clones while cell polarization and single-cell migration was impaired. Instead ITIH5 expression triggered the formation of epithelial-like cell clusters that underwent an epigenetic reprogramming. 214 promoter regions potentially marked with either H3K4 and /or H3K27 methylation showed a hyper- or hypomethylated DNA configuration due to ITIH5 expression finally leading to re-expression of the tumor suppressor DAPK1. In turn, RNAi-mediated knockdown of DAPK1 in ITIH5-expressing MDA-MB-231 single-cell clones clearly restored cell motility. Our results provide evidence that ITIH5 triggers a reprogramming of breast cancer cells with known stem CSC properties towards an epithelial-like phenotype through global epigenetic changes effecting known tumor suppressor genes like DAPK1. Therewith, ITIH5 may represent an ECM modulator in epithelial breast tissue mediating suppression of tumor initiating cancer cell characteristics which are thought being responsible for the metastasis of breast cancer. The online version of this article (doi:10.1186/s12943-017-0610-2) contains supplementary material, which is available to authorized users.