Previous studies have reported that E2F transcription factor 1 (E2F1) and DNA topoisomerase II alpha (TOP2A) are up-regulated in gastric cancer (GC), the corresponding unexplored regulatory mechanisms and the interactions of which in GC are worth figuring out. In this study, the expressions of E2F1 and TOP2A in GC tissues were assessed by real-time PCR (RT-PCR), and E2F1 binding sites in the TOP2A promoter region were predicted via bioinformatics analyses and confirmed using dual-luciferase reporter and ChIP assays. The viability, apoptosis, migration, and invasion of GC cells after transfection with sh-E2F1 or TOP2A plasmid were measured using methyl thiazolyl tetrazolium (MTT) assay, Hoechst 33258 staining/Annexin V/PI staining, and transwell assay. The expressions of E2F1, TOP2A, Cleaved caspase-3, Proliferating cell nuclear antigen (PCNA), E-cadherin, N-cadherin, and Vimentin in transfected cells were assessed by reverse transcription quantitative PCR (RT-qPCR) and western blot. Concretely, E2F1, as a transcription factor, has binding sites in the TOP2A promoter region. E2F1 and TOP2A levels were up-regulated and positively correlated with each other in GC tissues, i.e., overexpressed E2F1 increased TOP2A levels and E2F1 silencing decreased TOP2A levels in GC cells. Moreover, E2F1 silencing hindered GC cell viability, migration, and invasion, enhanced apoptosis, diminished the levels of PCNA, N-cadherin and Vimentin, and elevated those of Cleaved caspase-3 and E-cadherin in GC cells. However, overexpressed TOP2A reversed the above effects of E2F1 silencing. To sum up, E2F1-mediated up-regulation of TOP2A promotes the viability, migration, and invasion, and inhibits the apoptosis of GC cells.

既往研究报道E2F转录因子1（E2F1）和DNA拓扑异构酶IIα（TOP2A）在胃癌（GC）中上调，相应的未探索的调控机制及其在GC中的相互作用值得研究。在这项研究中，E2F1 和 TOP2A 在 GC 组织中的表达通过实时 PCR (RT-PCR) 进行评估，并通过生物信息学分析预测 TOP2A 启动子区域中的 E2F1 结合位点，并使用双荧光素酶报告基因和 ChIP 测定法进行确认. 使用甲基噻唑基四唑 (MTT) 法、Hoechst 33258 染色/膜联蛋白 V/PI 染色和 transwell 法检测转染 sh-E2F1 或 TOP2A 质粒后 GC 细胞的活力、凋亡、迁移和侵袭。E2F1、TOP2A、Cleaved caspase-3、增殖细胞核抗原（PCNA）、通过逆转录定量 PCR (RT-qPCR) 和蛋白质印迹评估转染细胞中的 E-钙粘蛋白、N-钙粘蛋白和波形蛋白。具体而言，E2F1 作为转录因子，在 TOP2A 启动子区域具有结合位点。E2F1 和 TOP2A 水平在 GC 组织中被上调并且彼此正相关，即，过表达的 E2F1 增加了 GC 细胞中的 TOP2A 水平，而 E2F1 沉默降低了 TOP2A 水平。此外，E2F1 沉默阻碍了 GC 细胞的活力、迁移和侵袭，增强了细胞凋亡，降低了 PCNA、N-cadherin 和 Vimentin 的水平，并提高了 GC 细胞中 Cleaved caspase-3 和 E-cadherin 的水平。然而，过表达的 TOP2A 逆转了 E2F1 沉默的上述影响。总之，E2F1 介导的 TOP2A 上调促进了生存能力、迁移和入侵，