Abstract：Objective: To investigate the influence of circular RNA BIRC6 (CircBIRC6) on cisplatin (DDP) resistance of non-small cell lung cancer (NSCLC) cells (A549).Methods: RT-qPCR was used to detect the expression of CircBIRC6 in DDP-resistant and sensitive lung cancer tissues and cells. Human NSCLC cell line A549 and DDP-resistant cells A549/DDP were cultured in vitro. A549/DDP cells were grouped into Control group, pcDNA group, pcBIRC6 group, si-CircBIRC6 group, si-NC group, si-BIRC6+inhibitor NC group, and si-BIRC6+miR-126-5p inhibitor group. RT-qPCR was applied to detect the expression of CircBIRC6 and miR-126-5p; CCK-8 assay was applied to detect cell proliferation and IC50 value for DDP; flow cytometry was applied to detect apoptosis; Western blot was applied to detect the protein expressions of JARID2, Cyclin D1, P21, and P-gp; dual-luciferase reporter gene assay was applied to verify the targeting relationship between CircBIRC6, JARID2 and miR-126-5p. Results: Compared with DDP-sensitive lung cancer tissues, the expression level of CircBIRC6 in DDP-resistant lung cancer tissues was greatly higher; compared with A549 cells, the expression level of CircBIRC6 in A549/DDP cells and the IC50 value of DDP on A549/DDP cells were greatly higher (P<0.05); the dual-luciferase reporter gene assay confirmed that CircBIRC6 and JARID2 had a targeting relationship with miR-126-5p. Compared with the pcDNA group, the A549/DDP cell proliferation, the protein expressions of CircBIRC6, JARID2, Cyclin D1 and P-gp, and IC50 value in the pcBIRC6 group were greatly higher, the apoptosis rate and the expression levels of miR-126-5p and P21 proteins were greatly lower (P<0.05); compared with the si-NC group, the A549/DDP cell proliferation, the protein expressions of CircBIRC6, JARID2, Cyclin D1 and P-gp, and IC50 value in the si-BIRC6 group were greatly lower, the apoptosis rate and the expression levels of miR-126-5p and P21 proteins were greatly higher (P<0.05); down-regulation of miR-126-5p expression reversed the proliferation-inhibiting and apoptosis-promoting effects of inhibiting CircBIRC6 expression on A549/DDP cells. Conclusion: CircBIRC6 is highly expressed in A549/DDP cells, which can inhibit the expression of miR-126-5p by targeting, up-regulate the expression of JARID2, and promote the resistance of A549/DDP cells to DDP.
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2022, Vol. 28 
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