Abstract: Background and purpose: This study was to investigate the effect of miRNA-486 on the growth of human colorectal cancer cell line SW620 xenograft in nude mice and to explore the possible mechanism of action. Methods: Eighteen mice were randomly divided into three groups, including the experimental group, the negative control group and the blank control group. Each group contained 6 mice. The SW620 cell line was inoculated subcutaneously into nude mice to establish the model of human colorectal cancer xenografts. Peritumoral injection of miRNA-486 overexpression plasmid, or blank vector and PBS were performed every 3 days. The volumes of subcutaneous tumors in each group of inoculated mice were compared. Then mice were sacrificed 3 weeks after infection. Immunohistochemistry and Western blot were used to measure the expression of neuropilin-2 (NRP2). Results: The growth rate of tumors in the experimental group was significantly lower than that in the negative control group and the blank control group. After 21 days, the size of transplanted tumors in the experimental group nude mice was (0.32±0.12) cm³, that in the negative control group was (0.77±0.31) cm³, and that in blank control group was (0.82±0.18) cm³. Tumor mass in the experimental group was significantly smaller than that in the other two groups (P=0.006<0.05). Tumor mass in the experimental group was (0.40±0.08) g, significantly smaller than that in the negative control group (0.75±0.18) g and in the blank control group (0.79±0.18) g (P=0.008<0.05). Compared with the expression of NRP2 in other groups, the growth of tumor in the experimental group declined (P=0.000<0.05). Conclusion: Colorectal cancer cell line SW620 xenografted tumor in nude mice can be suppressed after injection of miR-486, which may decrease the expression of NRP2.

Key words: miRNA-486, Colorectal cancer, Neuropilin -2 (NRP2), Xenografted tumor