Chirillo Roberta, Aversa Ilenia, Di Vito Anna, Salatino Alessandro, Battaglia Anna Martina, Sacco Alessandro, Di Sanzo Maddalena Adriana, Faniello Maria Concetta, Quaresima Barbara, Palmieri Camillo, Biamonte Flavia, Costanzo Francesco
Department of Experimental and Clinical Medicine, "Magna Græcia" University of Catanzaro, Catanzaro, Italy.
Department of Experimental and Clinical Medicine, Research Center of Biochemistry and Advanced Molecular Biology, "Magna Græcia" University of Catanzaro, Catanzaro, Italy.
Front Oncol. 2020 May 5;10:698. doi: 10.3389/fonc.2020.00698. eCollection 2020.
The cell-microenvironment communication is essential for homing of hematopoietic stem cells in stromal niches. Recent evidences support the involvement of epithelial-to-mesenchymal (EMT) process in hematopoietic stem cell homeostasis as well as in leukemia cells invasiveness and migration capability. Here, we demonstrate that the alteration of iron homeostasis and the consequent increase of redox metabolism, mediated by the stable knock down of ferritin heavy chain (FtH), enhances the expression of CXCR4 in K562 erythroleukemia cells, thus promoting CXCL12-mediated motility. Indeed, addition of the CXCR4 receptor antagonist AMD3100 reverts this effect. Upon FtH knock down K562 cells also acquire an "EMT-like" phenotype, characterized by the increase of and Vimentin with the parallel loss of E-cadherin. By using fibronectin as substrate, the cell adhesion assay further shows a reduction of cell adhesion capability in FtH-silenced K562 cells. Accordingly, confocal microscopy shows that adherent K562 control cells display a variety of protrusions while FtH-silenced K562 cells remain roundish. These phenomena are largely due to the reactive oxygen species (ROS)-mediated up-regulation of HIF-1α/CXCR4 axis which, in turn, promotes the activation of NF-κB and the enhancement of EMT features. These data are confirmed by treatments with either N-acetylcysteine (NAC) or AMD3100 or NF-κB inhibitor IκB-alpha which revert the FtH-silenced K562 invasive phenotype. Overall, our findings demonstrate the existence of a direct relationship among iron metabolism, redox homeostasis and EMT in the hematological malignancies. The effects of FtH dysregulation on CXCR4/CXCL12-mediated K562 cell motility extend the meaning of iron homeostasis in the leukemia cell microenvironment.
细胞与微环境之间的通讯对于造血干细胞在基质龛中的归巢至关重要。最近的证据支持上皮-间质转化（EMT）过程参与造血干细胞稳态以及白血病细胞的侵袭和迁移能力。在此，我们证明，通过稳定敲低铁蛋白重链（FtH）介导的铁稳态改变以及氧化还原代谢的相应增加，增强了K562红白血病细胞中CXCR4的表达，从而促进了CXCL12介导的运动性。事实上，添加CXCR4受体拮抗剂AMD3100可逆转这种效应。在敲低FtH后，K562细胞还获得了一种“EMT样”表型，其特征是波形蛋白增加而E-钙黏蛋白同时丢失。通过使用纤连蛋白作为底物，细胞黏附试验进一步显示，在FtH沉默的K562细胞中细胞黏附能力降低。相应地，共聚焦显微镜显示，贴壁的K562对照细胞呈现出各种突起，而FtH沉默的K562细胞则保持圆形。这些现象很大程度上归因于活性氧（ROS）介导的HIF-1α/CXCR4轴上调，进而促进NF-κB的激活和EMT特征的增强。用N-乙酰半胱氨酸（NAC）或AMD3100或NF-κB抑制剂IκB-α处理可逆转FtH沉默的K562侵袭性表型，从而证实了这些数据。总体而言，我们的研究结果表明血液系统恶性肿瘤中铁代谢、氧化还原稳态和EMT之间存在直接关系。FtH失调对CXCR4/CXCL12介导的K562细胞运动性的影响扩展了白血病细胞微环境中铁稳态的意义。
