Liu Yong, Xu Jianzhong, Jiang Min, Ni Lingna, Ling Yang
Department of Oncology, The Third Affiliated Hospital of Soochow University (Changzhou Tumor Hospital Affiliated to Soochow University), No. 68, Honghe Road, Changzhou, 213000 Jiangsu China.
Cancer Cell Int. 2020 Jun 22;20:261. doi: 10.1186/s12935-020-01358-w. eCollection 2020.
Circular RNA downstream neighbor of SON (circDONSON) has been revealed to promote gastric cancer (GC) growth and invasion, while the role and molecular mechanism underlying circDONSON in GC cisplatin (DDP) resistance remain unclear.
Levels of circDONSON, microRNA (miR)-802, and B lymphoma Mo-MLV insertion region 1 (BMI1) mRNA were detected using quantitative real-time polymerase chain reaction. Cell viability and apoptosis were measured by cell counting kit-8 assay, colony formation assay and flow cytometry, respectively. Protein levels of BMI1, Cyclin D1, p27, Caspase-3 Cleavage and Caspase-9 Cleavage were determined by western blot. The interaction between miR-802 and circDONSON or BMI1 was confirmed by dual-luciferase reporter assay. In vivo experiments were conducted via the murine xenograft model.
CircDONSON was elevated in GC tissues and cell lines, especially in DDP-resistant GC tissues and cells. Knockdown of circDONSON sensitized GC cells to DDP by inhibiting cell viability and promoting cell apoptosis in vitro. Further mechanism-related investigations suggested that circDONSON functioned as "sponge" by competing for miR-802 binding to modulate its target BMI1. Silencing miR-802 reversed the inhibition of DDP-resistance in GC cells induced by circDONSON down-regulation. Besides, miR-802 alleviated DDP resistance in GC cells by targeting BMI1. Functionally, circDONSON knockdown enhanced the cytotoxicity of DDP in GC in vivo.
Our findings demonstrated circDONSON promoted cisplatin resistance in gastric cancer cells by regulating miR-802/BMI1 axis, shedding light on the development of a novel therapeutic strategy to overcome chemoresistance in gastric cancer patients.
已发现SON基因下游环状RNA（circDONSON）可促进胃癌（GC）的生长和侵袭，而circDONSON在GC顺铂（DDP）耐药中的作用及分子机制仍不清楚。
采用定量实时聚合酶链反应检测circDONSON、微小RNA（miR）-802和B淋巴瘤Mo-MLV插入区1（BMI1）mRNA的水平。分别通过细胞计数试剂盒-8检测、集落形成试验和流式细胞术测定细胞活力和凋亡情况。通过蛋白质印迹法测定BMI1、细胞周期蛋白D1、p27、半胱天冬酶-3裂解产物和半胱天冬酶-9裂解产物的蛋白质水平。通过双荧光素酶报告基因试验证实miR-802与circDONSON或BMI1之间的相互作用。通过小鼠异种移植模型进行体内实验。
circDONSON在GC组织和细胞系中升高，尤其是在DDP耐药的GC组织和细胞中。敲低circDONSON可通过体外抑制细胞活力和促进细胞凋亡使GC细胞对DDP敏感。进一步的机制相关研究表明，circDONSON通过竞争结合miR-802发挥“海绵”作用来调节其靶标BMI1。沉默miR-802可逆转circDONSON下调诱导的GC细胞对DDP耐药性的抑制。此外，miR-802通过靶向BMI1减轻GC细胞的DDP耐药性。在功能上，敲低circDONSON可增强DDP在体内对GC的细胞毒性。
我们的研究结果表明，circDONSON通过调节miR-802/BMI1轴促进胃癌细胞的顺铂耐药性，为开发克服胃癌患者化疗耐药性的新治疗策略提供了线索。
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