Abstract: Objective To investigate whether LncRNA ZFAS1 promotes proliferation and inhibit apoptosis in diffuse large B cell lymphoma (DLBCL) cell by regulating miR-34b-5p. Methods Real-time fluorescence quantitative PCR (RT-qPCR) was performed to detect the expression levels of LncRNA ZFAS1 and miR-34b-5p in tumor tissues of DLBCL patients and DLBCL cell lines. The vectors with or without the sequences for ZFAS1 knock-down and miR-34b-5p inhibition / overexpression were transfected into the SU-DHL-4 cells using Lipofectamine 2000 reagent. RTqPCR was performed to detect the knockdown and overexpression efficiency. The targeting relationship of ZFAS1 and miR-34b-5p was analyzed by dual luciferase reporter gene assay. SU-DHL-4 cells were then randomly grouped into control group, sh-ZFAS1 group, miR-34b-5p inhibitor group and shRNA-ZFAS1 + miR-34b-5p inhibitor group. Colony formation assay and flow cytometry were performed to detect cell proliferation and apoptosis, respectively. Western blotting assay was performedto detect the expression levels of apoptosis-related proteins. Results The expression level of ZFAS1 was increased in DLBCL patients and cell lines, while the expression level of miR-34b-5p was decreased. miR-34b-5p was targeted and negatively regulated by ZFAS1. The expression level of miR- 34b-5p was increased in the sh-ZFAS1 group and was decreased in the miR-34b-5p inhibitor group, when compared with those in the control group. The expression level of miR-34b-5p was higher in the sh-ZFAS1 + miR-34b-5p inhibitor group than that in the miR-34b-5p inhibitor group. Knockdown of ZFAS1 expression inhibited the proliferation, promoted the apoptosis, and decreased the mitochondrial membrane potential in SU-DHL-4 cells, while the Bax / Bcl-2 and cleaved-caspase-3 / caspase-3ratios were elevated. Conclusion LncRNA ZFAS1 promotes the proliferation and inhibits the apoptosis in SU-DHL-4 cells through down-regulation of miR-34b-5p.

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