The International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200030, China.
Cell Prolif. 2013 Aug;46(4):425-35. doi: 10.1111/cpr.12043.
Ovarian cancer stem-like cells (CSCs), which can form non-adherent sphere cells in a stem-cell selection culture system, exhibit stemness and drug resistance to chemotherapeutics, which are properties not observed in differentiated cells. Recent studies have demonstrated that Kruppel-like factor 5 (KLF5) is involved in cell proliferation and mediates cell survival and tumourigenesis. Here, we investigated the role of KLF5 and its downstream target survivin, in strengthening drug resistance of ovarian CSCs.
Ovarian cancer cell line SKOV3 was cultured under serum-free conditions and differentiating conditions to promote formation of sphere cells and differentiated cells, respectively. siRNA-KLF5 was used to knock down KLF5, and survivin expression vector was used to overexpress survivin. Cells were further analysed by qPCR, immunofluorescence staining and western blotting. Chromatin immunoprecipitation (ChIP) assay and electrophoretic mobility shift assay (EMSA) were performed to investigate the relationship between KLF5 and survivin expression. Drug resistance was examined by MTT and apoptosis assays.
KLF5 was highly expressed in the ovarian cancer cell line SKOV3 sphere cells, accompanied by elevated survivin expression. Silencing KLF5 by small interfering RNA in sphere cells down-regulated survivin expression, which also sensitized the sphere cells to apoptosis induced by chemotherapeutic drugs (cisplatin or paclitaxel). Furthermore, ChIP assay, survivin overexpression and EMSA results indicated that KLF5 controlled survivin expression by directly binding the surivin promoter in the cells.
The KLF5-mediated signalling pathway is a potential target for elimination of ovarian CSCs.
卵巢癌干细胞样细胞（CSCs）在干细胞选择培养系统中可形成非贴壁球体细胞，表现出干性和对化疗药物的耐药性，而这些特性在分化细胞中观察不到。最近的研究表明，Krüppel 样因子 5（KLF5）参与细胞增殖，并介导细胞存活和肿瘤发生。在这里，我们研究了 KLF5 及其下游靶标生存素在增强卵巢 CSCs 耐药性中的作用。
卵巢癌细胞系 SKOV3 在无血清条件下和分化条件下培养，分别促进球体细胞和分化细胞的形成。使用 siRNA-KLF5 敲低 KLF5，使用生存素表达载体过表达生存素。通过 qPCR、免疫荧光染色和 Western blot 进一步分析细胞。进行染色质免疫沉淀（ChIP）实验和电泳迁移率变动分析（EMSA）以研究 KLF5 和生存素表达之间的关系。通过 MTT 和凋亡实验检测耐药性。
KLF5 在卵巢癌细胞系 SKOV3 球体细胞中高表达，伴随着生存素表达的升高。在球体细胞中通过小干扰 RNA 沉默 KLF5 下调了生存素的表达，这也使球体细胞对化疗药物（顺铂或紫杉醇）诱导的凋亡敏感。此外，ChIP 实验、生存素过表达和 EMSA 结果表明，KLF5 通过直接结合细胞中的生存素启动子来控制生存素的表达。
KLF5 介导的信号通路是消除卵巢 CSCs 的潜在靶点。
