Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan, Shandong, 250012, People's Republic of China.
Affiliated Reproductive Hospital of Shandong University, Jinan, Shandong, 250012, People's Republic of China.
Stem Cell Res Ther. 2021 Mar 16;12(1):186. doi: 10.1186/s13287-021-02256-2.
Ovarian cancer stem cells (OCSC), endowed with tumor-initiating and self-renewal capacity, would account not only for the tumor growth, the peritoneal metastasis, and the relapse, but also for the acquisition of chemotherapy resistance. Nevertheless, figuring out their phenotypical and functional traits has proven quite challenging, mainly because of the heterogeneity of ovarian cancer. A deeper understanding of OCSC mechanisms will shed light on the development of the disease. Therefore, we aim to explore it for the design of innovative treatment regimens which aim at the eradication of ovarian cancer through the elimination of the CSC component.
In this study, immunohistochemistry assay and western blot assay were used to detect protein expression in the primary tumor and peritoneal multi-cellular aggregates/spheroids (MCAs/MCSs). OCSCs induced from cell line SKOV3 and HO-8910 were enriched in a serum-free medium (SFM). The effect of EIF5A2 on CSC-like properties was detected by sphere-forming assays, re-differentiation assays, quantitative real-time polymerase chain reaction, western blotting, flow cytometry, cell viability assays, immunofluorescence staining, and in vivo xenograft experiments. RNA-sequencing (RNA-seq) was used to reveal the mechanism by which EIF5A2 positively modulates the stem-like properties of ovarian cancer cells.
Expression of EIF5A2 was significantly higher in peritoneal MCAs/MCSs compared to matched primary tumors, and EIF5A2 was also unregulated in ovarian cancer cell line-derived spheroids. Knockdown of EIF5A2 reduced the expression of the stem-related markers (ALDH1A1 and OCT-4), inhibited self-renewal ability, improved the sensitivity to chemotherapeutic drugs, and inhibited tumorigenesis in vivo. Mechanistic studies revealed that EIF5A2 knockdown reduced the expression of KLF4, which could partially rescue stem-like properties abolished by EIF5A2 knockdown or strengthened by EIF5A2 overexpression, through the transcription factor E2F1, which directly bind to KLF4 promoter.
Our results imply that EIF5A2 positively regulates stemness in ovarian cancer cells via E2F1/KLF4 pathway and may serve as a potential target in CSCs-targeted therapy for ovarian cancer.
卵巢癌干细胞（OCSC）具有肿瘤起始和自我更新能力，不仅会导致肿瘤生长、腹膜转移和复发，还会导致化疗耐药。然而，要弄清楚它们的表型和功能特征非常具有挑战性，主要是因为卵巢癌的异质性。更深入地了解 OCSC 机制将为疾病的发展提供启示。因此，我们旨在探索其机制，设计旨在通过消除 CSC 成分来根除卵巢癌的创新治疗方案。
在这项研究中，免疫组织化学检测和 Western blot 检测用于检测原发性肿瘤和腹膜多细胞聚集物/球体（MCA/MSC）中的蛋白表达。从细胞系 SKOV3 和 HO-8910 中诱导的 OCSC 在无血清培养基（SFM）中富集。通过球体形成试验、再分化试验、实时定量聚合酶链反应、Western blot、流式细胞术、细胞活力测定、免疫荧光染色和体内异种移植实验检测 EIF5A2 对 CSC 样特性的影响。RNA 测序（RNA-seq）用于揭示 EIF5A2 正向调节卵巢癌细胞干性特性的机制。
与匹配的原发性肿瘤相比，EIF5A2 在腹膜 MCA/MSC 中的表达明显更高，并且在卵巢癌细胞系衍生的球体中也上调。EIF5A2 敲低降低了干细胞相关标志物（ALDH1A1 和 OCT-4）的表达，抑制了自我更新能力，提高了对化疗药物的敏感性，并抑制了体内肿瘤发生。机制研究表明，EIF5A2 敲低降低了 KLF4 的表达，通过转录因子 E2F1 直接结合 KLF4 启动子，EIF5A2 敲低或 EIF5A2 过表达部分挽救了由 EIF5A2 敲低或 EIF5A2 过表达引起的干性特性缺失，从而降低了 KLF4 的表达。
我们的结果表明，EIF5A2 通过 E2F1/KLF4 途径正向调节卵巢癌细胞的干性，并可能成为卵巢癌 CSC 靶向治疗的潜在靶点。
