Objective:To explore whether microRNA (miRNA) -181b-5p inhibits the proliferation and invasion of cutaneous melanoma cells by targeting pleckstrin (PLEK) .Methods:Bioinformatics methods were used to analyze cutaneous melanoma-associated core genes; dual-luciferase reporter assay was performed to verify the targeted interaction between miRNA-181b-5p and PLEK. Oligo RNA and small interfering RNA (siRNA) were used to regulate the expression of miRNA-181b-5p and PLEK in A375 cells respectively in this experiment, and A375 cells were divided into the following groups in detail: mimic negative control group, miRNA-181b-5p mimic group, inhibitor negative control group, miRNA-181b-5p inhibitor group, PLEK siRNA group, siRNA negative control group, miRNA-181b-5p inhibitor + control siRNA co-transfection group and miRNA-181b-5p inhibitor + PLEK siRNA3 co-transfection group. After 48-hour treatment, qPCR was performed to determine the mRNA expression of miRNA-181b-5p and PLEK in A375 cells, Western blot analysis to determine the PLEK protein expression, and Transwell assay to assess the invasive ability of A375 cells; after additional 24-96 hours of culture, cell counting kit-8 (CCK8) assay was conducted to assess the proliferative ability of A375 cells.Results:PLEK was the core gene for cutaneous melanoma. PLEK expression in the cutaneous melanoma in situ tissues was significantly higher than that in the paracancerous tissues ( P = 0.031) , but lower than that in the metastatic tissues ( P = 0.001) . Compared with human epidermal melanocytes HEMa-LP, the mRNA and protein expression of PLEK significantly increased in A375 cells (mRNA: 3.884 ± 0.156 vs. 0.997 ± 0.010, t = 18.48, P < 0.001; protein: 2.840 ± 0.301 vs. 1.029 ± 0.094, t = 5.47, P = 0.005) , but the miRNA-181b-5p expression significantly decreased in A375 cells (0.333 ± 0.042 vs. 0.967 ± 0.069, t = 7.83, P = 0.001) . Dual-luciferase reporter assay showed targeted binding of miRNA-181b-5p to PLEK. Compared with the mimic negative control group, the miRNA-181b-5p mimic group showed significantly decreased survival rate of A375 cells (48 hours: t = 7.96, P = 0.015; 72 hours: t = 7.50, P = 0.002; 96 hours: t = 7.96, P = 0.001) , and significantly decreased invasive ability of A375 cells ( t = 5.07, P = 0.007) ; on the contrary, the survival rate and invasive ability of A375 cells were significantly higher in the miRNA-181b-5p inhibitor group than in the inhibitor negative control group (survival rate: 24 hours, t =5.38, P = 0.013; 48 hours, t = 5.36, P = 0.013; 72 hours, t =7.63, P = 0.005; 96 hours, t = 5.99, P = 0.004; invasive ability: t = 7.24, P = 0.002) ; compared with the siRNA negative control group, the proliferative and invasive ability of A375 cells significantly decreased in the PLEK siRNA group (proliferative ability: 48, 72, 96 hours, P = 0.015, 0.011, 0.001, respectively; invasive ability: t = 4.93, P = 0.008) ; compared with the miRNA-181b-5p inhibitor + control siRNA co-transfection group, the miRNA-181b-5p inhibitor + PLEK siRNA co-transfection group showed significantly decreased proliferation rate and invasive ability of A375 cells (proliferation rate: 24, 48, 72, 96 hours, P = 0.042, 0.042, 0.037, 0.017, respectively; invasive ability: t = 8.52, P = 0.001) . Conclusion:miRNA-181b-5p can inhibit the proliferation and invasion of cutaneous melanoma A375 cells, likely by down-regulating the PLEK expression.