Objective To explore the effect of microRNA-613 (miR-613)/Wee1 axis on the radiosensitivity of colorectal cancer cells.Methods A total of 20 patients with radiosensitive colorectal cancer and 20 patients with radioresistance were selected from Yan'an Hospital Affiliated to Kunming Medical University from November 2016 to May 2017.Human colorectal cancer cell lines LoVo and HCT116 were selected and the radioresistant cell lines LoVo/R and HCT116/R were established for subsequent experiments.Real-time fluorescence quantitative PCR (qRT-PCR) was used to detect the expression of miR-613 and Wee1 in colorectal cancer tissues and cell lines.The radioresistant cells were transfected by miR-613 mimic,and non-transfected cells were used as control group.The effects of miR-613 overexpression on the proliferation,invasion and cell cycle of radiation resistance of colorectal cancer cells at different radiation doses were evaluated by CCK-8 assay,Transwell assay and Western blotting,respectively.Furthermore,dual-luciferase reporter gene assay was used to verify whether Wee1 was a target gene of miR-613.si-Wee1 was transfected into radioresistant cells of colorectal cancer,or co-transfected with si-Wee1 and miR-613 inhibitor,and non-transfected cells were used as control group.The effects of miR-613/Wee1 axis on cell proliferation,invasion and cell cycle were detected by CCK-8,Transwell and Western blotting at different radiation doses.Results The expression of miR-613 was downregulated in the radiation resistance group of patients (1.54 ± 0.25 vs.2.64 ± 0.45;t =3.140,P =0.009) and radiation resistance cell lines (LoVo/R vs.LoVo:1.03 ± 0.12 vs.3.05 ± 0.15;t =8.944,P =0.006;HCT116/R vs.HCT116:1.01 ±0.11 vs.2.85 ±0.16;t =8.050,P =0.008).Overexpression of miR-613 was significantly inhibited the proliferation (LoVo/R:t6 Gy =6.018,P =0.013;HCT116/R:t6Gy =5.634,P =0.015) and invasion (LoVo/R:45.00 ± 8.95 vs.180.15 ± 6.95,t6 Gy =11.93,P =0.003;HCT116/R:49.97 ±6.21 vs.170.20 ±7.03,t6 Gy =12.82,P =0.006) of LoVo/R and HCT116/R cells and decreased the expression levels of G2-M phase cell cycle correlated proteins (CDK1 and cyclin B).Moreover,dual-luciferase reporter gene assay confirmed that Wee1 was a target of miR-613.Mechanistically,overexpression of miR-613 promoted the radiosensitivity of LoVo/R and HCT116/R cells through inhibiting cell proliferation (compared with si-Wee1 group,co-transfected with si-Wee1 and miR-613 inhibitor,and control group,LoVo/R:F8 Gy =40.742,P =0.007;HCT116/R:F8 Gy =28.958,P =0.011),invasion (LoVo/R:F8 Gy =55.413,P =0.004;HCT116/R:F8 Gy =65.634,P =0.003) and arresting cell at G2-M phase via downregulating Wee1.Conclusion miR-613/Wee1 axis plays a certain role in regulating the radiation resistance of colorectal cancer cells,overexpression of miR-613 may reverse the radiation resistance of colorectal cancer cells.