Objective:To investigate the expression difference of miR-3189-3p in renal cancer tissue and adjacent tissue and its effect on the biological function of renal cancer cells.Methods:quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression level of miR-3189-3p in renal cancer tissues and adjacent tissues, renal cancer cell lines (Caki-1, ACHN, A498, OS-RC-2) and normal renal tubular epithelial cells HK-2. miR-NC or miR-3189-3p mimics were transfected into renal cancer cells with the lowest expression of miR-3189-3p, respectively, named miR-NC group and miR-3189-3p group. The effects of miR-3189-3p on the proliferation and invasion of renal cancer cells were detected by CCK-8 method and Transwell migration experiment. miRanda and miRTarBase software was used to predict the downstream gene of miR-3189-3p. The dual luciferase reporter gene experiment was used to verify the downstream gene of miR-3189-3p. qRT-PCR and Western blotting were used to detect the expression of miR-3189-3p downstream gene. Measurement data were expressed as mean ± standard deviation ( ± s), and t-test was used for comparison between groups. Results:The relative expression of miR-3189-3p in renal cancer tissue and paracancerous tissue was 1.97±0.61 and 6.19±0.73, respectively, and the relative expression of miR-3189-3p in renal cancer tissue was lower than that in paracancerous tissue ( P<0.01). The relative expression of miR-3189-3p in renal cancer cell lines was lower than that in HK-2 cells ( P<0.05). The relative expression of miR-3189-3p in OS-RC-2 cells was the lowest ( P<0.01). The relative expression levels of miR-3189-3p in OS-RC-2 cells in the miR-NC group and miR-3189-3p group were 1.01±0.11 and 9.27±1.43, respectively, and the relative expression levels of miR-3189-3p in the miR-NC group significantly lower than the miR-3189-3p group ( P<0.01). Compared with the miR-NC group, the proliferation ability of OS-RC-2 cells with high expression of miR-3189-3p was significantly reduced ( P<0.05). The numbers of penetrating cells in the miR-NC group and miR-3189-3p group were 165.40±17.02 and 41.07±6.36, respectively, and the invasive ability of OS-RC-2 cells in the miR-3189-3p group was significantly reduced ( P<0.01). The target gene of miR-3189-3p is Aquaporin 3 ( AQP3) and miR-3189-3p can target AQP3 mRNA ( P<0.01). Compared with the miR-NC group, the expression of AQP3 gene in the high-expressing miR-3189-3p cells was significantly reduced at both the mRNA level and the protein level ( P<0.01). Conclusions:The expression of miR-3189-3p is down-regulated in renal cell carcinoma. High expression of miR-3189-3p can significantly inhibit the proliferation and invasion of renal cell carcinoma OS-RC-2 cells. The molecular mechanism is that miR-3189-5p targets and inhibits the expression of AQP3 gene.