Objective:To investigate the expression of long non-coding RNA(lncRNA) ZFP36-AS1 in bladder cancer and the effect of ZFP36-AS1/miR-221 axis on the proliferation and immune escape of bladder cancer cells.Methods:The expression difference of ZFP36-AS1 in bladder cancer tissues was analyzed by cBioPortal database. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to analyze the expression difference of ZFP36-AS1 in bladder cancer cell lines (J82, RT-4, MGH-U3, 5637). MGH-U3 cells were randomly divided into negative control (NC) group and ZFP36-AS1 group, which were transfected with pcDNA3.1-NC plasmid and pcDNA3.1-ZFP36-AS1 plasmid, respectively. Colony formation assay and flow cytometry were used to analyze the proliferation activity and cell cycle of MGH-U3 cells, respectively. T lymphocytes were co-cultured with MGH-U3 cells in each group, and the levels of interleukin-10 (IL-10), γ-interferon (IFN-γ), and interleukin-4 (IL-4) in the supernatants of each group were detected by enzyme-linked immunosorbent assay (ELISA). The dual-luciferase reporter gene assay verified the targeting relationship between ZFP36-AS1 and miR-221. The effect of ZFP36-AS1 on the expression of miR-221 in MGH-U3 cells was detected by RT-qPCR. Western blotting was used to detect the effect of ZFP36-AS1/miR-221 axis on the protein expression of CDK3, Cyclin C, CDK5, Cyclin D1 and Cyclin D3 in MGH-U3 cells.Results:Compared with normal bladder tissue, ZFP36-AS1 was abnormally low-expressed in bladder cancer tissue ( P<0.01). Compared with SV-HUC-1 cells, ZFP36-AS1 was abnormally low-expressed in bladder cancer cell lines (J82, RT-4, MGH-U3, 5637) ( P<0.01), and the expression was lowest in MGH-U3 cells ( P<0.01). The number of MGH-U3 cell colonies formed in the NC group and the ZFP36-AS1 group were (220.80±34.65) and (77.84±19.11), respectively, and the number of MGH-U3 cell colonies formed in the ZFP36-AS1 group was significantly down-regulated, the difference was statistically significant ( P<0.01). The proportions of G 0/G 1 phase cells in NC group and ZFP36-AS1 group were (48.04±2.89)% and (72.89±3.46)%, respectively, and the proportion of S phase cells were (35.38±2.98)% and (20.62±2.56)%, respectively. The proportion of G 2/M stage cells was (16.59±1.46)% and (6.48±1.50)%, respectively. The proportion of cells in G 0/G 1 phase were up-regulated in ZFP36-AS1 group ( P<0.01), and the proportion of cells in S phase and G 2/M phase were both down-regulated ( P<0.01). Compared with the NC group, the levels of IL-4 and IFN-γ in the ZFP36-AS1 group were significantly up-regulated ( P<0.01), and the level of IL-10 was significantly down-regulated ( P<0.01). ZFP36-AS1 can target miR-221 ( P<0.01). The relative expression of miR-221 in the NC group and the ZFP36-AS1 group was 6.84±1.35 and 1.00±0.21, respectively. Compared with the NC group, overexpression of ZFP36-AS1 could significantly inhibit the expression of miR-221 ( P<0.01). Compared with the NC group, the expressions of CDK3, Cyclin C, CDK5, Cyclin D1, and Cyclin D3 in the ZFP36-AS1 group were significantly decreased. Conclusion:ZFP36-AS1 is abnormally low-expressed in bladder cancer, and it reduces the proliferation activity of bladder cancer cells and inhibits their immune escape by inhibiting the expression of miR-221.