Department of General Surgery, The Affiliated Zhuzhou Hospital Xiangya Medical College CSU, Zhuzhou, China.
Department of Basic Medicine, Hunan Traditional Chinese Medicine College, Zhuzhou, China.
Neoplasma. 2021 Jan;68(1):108-118. doi: 10.4149/neo_2020_200417N414. Epub 2020 Nov 5.
Circular RNA F-box and WD repeat domain containing 7 (circ-FBXW7) has been revealed to be involved in the tumorigenesis of colorectal cancer (CRC). Exosomes are critical mediators of intercellular communication. However, the role of exosomal circ-FBXW7 in the CRC oxaliplatin resistance remains unknown. Cell viability, apoptosis, motility, and drug efflux were measured by the cell counting kit-8 assay, flow cytometry, transwell assay, and atomic absorption spectrophotometry, respectively. The expression of circ-FBXW7 and microRNA (miR)-18b-5p was detected using the quantitative real-time polymerase chain reaction. Western blot was used to determine multidrug resistance protein 1 (MRP1), myeloid cell leukemia-1 (MCL-1), CD9, CD63, Caspase3, E-cadherin, and N-cadherin. Exosomes were isolated and captured using the ultracentrifugation method and transmission electron microscopy. The interaction between circ-FBXW7 and miR-18b-5p was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. In vivo experiments were conducted using the murine xenograft model. Our results showed that circ-FBXW7 was decreased in oxaliplatin-resistant CRC patients and cells. circ-FBXW7 was secreted by circ-FBXW7-transfected FHC cells and could be transferred to resistant CRC cells through the exosome secretion. Subsequently, in vitro and in vivo studies demonstrated exosomal circ-FBXW7 led resistant cells sensitive to oxaliplatin, increased the oxaliplatin-induced apoptosis, inhibited oxaliplatin-induced epithelial-mesenchymal transition, and suppressed oxaliplatin efflux. miR-18b-5p was increased in oxaliplatin-resistant CRC patients and cells and was confirmed to be a target of circ-FBXW7. Immediately, the rescue assay showed exosome-mediated transfer of circ-FBXW7 enhanced oxaliplatin sensitivity by binding to miR-18b-5p in vitro and in vivo. To conclude, the circ-FBXW7 delivery by exosomes could ameliorate chemoresistance to oxaliplatin in CRC by directly binding to miR-128-3p, suggesting a promising therapeutic strategy for oxaliplatin-resistant CRC patients.
环状 RNA F-box 和 WD 重复结构域包含 7（circ-FBXW7）已被证明参与结直肠癌（CRC）的肿瘤发生。外泌体是细胞间通讯的重要介质。然而，外泌体 circ-FBXW7 在 CRC 奥沙利铂耐药中的作用尚不清楚。通过细胞计数试剂盒-8 测定、流式细胞术、Transwell 测定和原子吸收分光光度法分别测量细胞活力、细胞凋亡、运动性和药物外排。使用实时定量聚合酶链反应检测 circ-FBXW7 和 microRNA（miR）-18b-5p 的表达。使用 Western blot 测定多药耐药蛋白 1（MRP1）、髓样细胞白血病-1（MCL-1）、CD9、CD63、Caspase3、E-钙粘蛋白和 N-钙粘蛋白。使用超速离心法和透射电子显微镜分离和捕获外泌体。通过双荧光素酶报告基因检测和 RNA 免疫沉淀检测证实 circ-FBXW7 与 miR-18b-5p 之间的相互作用。使用小鼠异种移植模型进行体内实验。我们的结果表明，circ-FBXW7 在奥沙利铂耐药 CRC 患者和细胞中减少。circ-FBXW7 由转染 circ-FBXW7 的 FHC 细胞分泌，并可通过外泌体分泌转移至耐药 CRC 细胞。随后，体外和体内研究表明，外泌体 circ-FBXW7 使耐药细胞对奥沙利铂敏感，增加奥沙利铂诱导的细胞凋亡，抑制奥沙利铂诱导的上皮-间充质转化，并抑制奥沙利铂外排。miR-18b-5p 在奥沙利铂耐药 CRC 患者和细胞中增加，并被证实是 circ-FBXW7 的靶标。立即，挽救试验表明，外泌体介导的 circ-FBXW7 转移通过在体外和体内与 miR-18b-5p 结合增强了奥沙利铂的敏感性。总之，外泌体递送 circ-FBXW7 可通过直接结合 miR-128-3p 改善 CRC 对奥沙利铂的化疗耐药性，为奥沙利铂耐药 CRC 患者提供了一种有前途的治疗策略。
