Circ_0020123 enhances the cisplatin resistance in non-small cell lung cancer cells partly by sponging miR-140-3p to regulate homeobox B5 (HOXB5)

Cisplatin (DDP) therapy is widely used for the treatment of non-small cell lung cancer (NSCLC), but the curative effect is limited by chemoresistance. This study was designed to explore circ_0020123 function in DDP resistance of NSCLCDDP. Expression detection for circ_0020123, microRNA-140-3p (miR-140-3p) and homeobox B5 (HOXB5) was performed by real-time polymerase chain reaction (qRT-PCR). Half inhibitory concentration (IC50) of DDP and cell proliferation was detected by Cell Counting Kit-8 (CCK-8) assay. Colony formation ability was assessed using colony formation assay. Cell migration and invasion were evaluated via transwell assay. Cell apoptosis was examined by flow cytometry. Protein analysis was conducted by Western blot. Dual-luciferase reporter assay was used to affirm target interaction. Circ_0020123 expression was upregulated in DDP-resistant NSCLC cells. DDP resistance was reduced by downregulation of circ_0020123 in NSCLC cells. Circ_0020123 was identified as a miR-140-3p sponge. The effect of si-circ_0020123 on DDP resistance was partly associated with miR-140-3p upregulation. HOXB5 was a downstream target for miR-140-3p. Overexpression of HOXB5 mitigated miR-140-3p-induced inhibition of DDP resistance in NSCLC cells. Circ_0020123 upregulated the level of HOXB5 partly via sponging miR-140-3p. Also, circ_0020123 promoted tumor growth in NSCLC/DDP xenografts by regulating miR-140-3p and HOXB5 levels at least in part. These results revealed that circ_0020123 promoted DDP resistance in NSCLC cells partly by targeting miR-140-3p/HOXB5 axis, indicating that circ_0020123 might be used as a molecular target in DDP treatment for NSCLC.

顺铂（Cisplatin, DDP）疗法广泛应用于非小细胞肺癌（non-small cell lung cancer, NSCLC）的临床治疗，但其疗效常因化疗耐药而受到限制。本研究旨在探究circ_0020123在NSCLC顺铂耐药中的调控功能。采用实时荧光定量聚合酶链反应（real-time polymerase chain reaction, qRT-PCR）检测circ_0020123、微小RNA-140-3p（microRNA-140-3p, miR-140-3p）以及同源盒B5（homeobox B5, HOXB5）的转录表达水平；通过细胞计数试剂盒-8（Cell Counting Kit-8, CCK-8）实验检测顺铂的半数抑制浓度（half inhibitory concentration, IC50）与细胞增殖活性；采用克隆形成实验评估细胞的克隆形成能力；通过Transwell实验检测细胞的迁移与侵袭能力；采用流式细胞术检测细胞凋亡水平；采用蛋白质印迹（Western blot）实验进行蛋白水平分析；利用双荧光素酶报告基因实验验证靶标分子间的相互作用。实验结果显示，circ_0020123在顺铂耐药的NSCLC细胞中表达显著上调；下调circ_0020123的表达可减弱NSCLC细胞的顺铂耐药性。经鉴定，circ_0020123可作为miR-140-3p的分子海绵；敲低circ_0020123对顺铂耐药性的调控作用部分依赖于miR-140-3p的表达上调。HOXB5是miR-140-3p的下游靶基因；过表达HOXB5可逆转miR-140-3p介导的NSCLC细胞顺铂耐药抑制效应。circ_0020123可通过海绵吸附miR-140-3p，部分上调HOXB5的表达水平。此外，circ_0020123可通过调控miR-140-3p与HOXB5的表达水平，在一定程度上促进NSCLC/DDP异种移植瘤的体内生长。综上，circ_0020123可通过靶向miR-140-3p/HOXB5信号轴，部分增强NSCLC细胞的顺铂耐药性，提示circ_0020123有望成为NSCLC顺铂治疗的潜在分子靶点。