Zhang Gui Hong, Kai Jin Yan, Chen Miao Miao, Ma Qian, Zhong Ai Ling, Xie Su Hong, Zheng Hui, Wang Yan Chun, Tong Ying, Tian Yuan, Lu Ren Quan, Guo Lin
Department of Clinical Laboratory, Fudan University, Shanghai Cancer Center, Shanghai 200032, P.R. China.
Oncol Lett. 2019 Oct;18(4):4194-4202. doi: 10.3892/ol.2019.10772. Epub 2019 Aug 22.
Interaction between endoplasmic reticulum (ER) stress and oxidative stress contributes to the occurrence and development of various types of cancer. The X-box-binding protein 1 (XBP1), which is an important transcription factor in ER stress-related pathways, has also been reported to serve a protective role against oxidative stress. However, the role of XBP1 in serous ovarian cancer (SOC) remains elusive. The aim of the present study was to explore the biological function of XBP1 in SOC cells under normal or oxidative stress conditions. The expression of XBP1 was downregulated in the SOC cell lines A2780 and HO8910 by lentivirus-mediated short hairpin RNA (shRNA). Cell proliferative ability was evaluated by cell colony formation and viability assays. The sensitivity of ovarian cancer cells to oxidative stress was evaluated using cell survival rate and apoptotic rate, determined by the Cell Counting Kit-8 assay and flow cytometry, respectively. Reactive oxygen species (ROS) levels were measured by flow cytometry and cell immunofluorescence using a dichlorodihydrofluorescein diacetate probe. The mRNA and protein expression levels were detected by fluorescence quantitative polymerase chain reaction and western blot analysis, respectively. The results demonstrated that XBP1 was overexpressed in SOC compared with normal ovarian epithelial cells, and that downregulation of XBP1 significantly reduced cell proliferative ability. In addition, the downregulation of XBP1 significantly enhanced the sensitivity of SOC cells to HO by increasing the intracellular ROS levels. The phosphorylation level of the mitogen-activated protein kinase (MAPK) p38 decreased in the cells of the XBP1-knockdown group. These results indicated that XBP1 may serve a protective role against oxidative stress in SOC cells, and the underlying molecular mechanism may be associated with the downregulation of phosphorylated p38. Therefore, targeting XBP1 may act synergistically with ROS inducers in the treatment of SOC.
内质网（ER）应激与氧化应激之间的相互作用促进了各类癌症的发生和发展。X盒结合蛋白1（XBP1）是内质网应激相关通路中的一种重要转录因子，据报道它对氧化应激也具有保护作用。然而，XBP1在浆液性卵巢癌（SOC）中的作用仍不清楚。本研究的目的是探讨在正常或氧化应激条件下XBP1在SOC细胞中的生物学功能。通过慢病毒介导的短发夹RNA（shRNA）下调SOC细胞系A2780和HO8910中XBP1的表达。通过细胞集落形成和活力测定评估细胞增殖能力。分别采用细胞计数试剂盒-8法和流式细胞术，通过细胞存活率和凋亡率评估卵巢癌细胞对氧化应激的敏感性。使用二氯二氢荧光素二乙酸酯探针通过流式细胞术和细胞免疫荧光测定活性氧（ROS）水平。分别通过荧光定量聚合酶链反应和蛋白质免疫印迹分析检测mRNA和蛋白质表达水平。结果表明，与正常卵巢上皮细胞相比，XBP1在SOC中过表达，并且XBP1的下调显著降低了细胞增殖能力。此外，XBP1的下调通过增加细胞内ROS水平显著增强了SOC细胞对HO的敏感性。XBP1敲低组细胞中丝裂原活化蛋白激酶（MAPK）p38的磷酸化水平降低。这些结果表明，XBP1可能在SOC细胞中对氧化应激起保护作用，其潜在的分子机制可能与磷酸化p38的下调有关。因此，靶向XBP1可能在SOC的治疗中与ROS诱导剂起协同作用。
