miR-331-3p targeted the 3′-UTR of NRP2 and inhibited the expression of NRP2. A, The predicted binding sequences for miR-331-3p within the 3′-UTR of NRP2. Seed sequences are illustrated. B, RT-qPCR result showed the mRNA level of NRP2 was significantly upregulated in TNBC tissues compared to the matched adjacent nontumorous tissues. C, Linear correlation analysis between NRP2 and miR-331-3p expression in TNBC tissues using Spearman correlation analysis. D and E, Overexpression of miR-331-3p markedly decreased the luciferase activity in cells carrying WT 3′-UTR of NRP2 mRNA, while the mutated 3′-UTR of NRP2 was insensitive to miR-331-3p transfection. F and G, The mRNA and protein expression of NRP2 after introducing of miR-331-3p was measured by RT-qPCR and Western blot analysis, respectively. mRNA indicates messenger RNA; NRP2, neuropilin-2; RT-qPCR, real-time quantitative polymerase chain reaction; TNBC, triple-negative breast cancer; UTR, untranslated region; WT, wild-type.