Abstract: Objective To explore the impact of miR-221 overexpression on the expression of N-MYC level and the cell proliferation in neuroblastoma SH-SY5Y cells. Methods miR-221 overexpression lentiviral vector was constructed and its stable transfection cells were established. Untreated group, control group and miR-221 group were set up. The expression of miR-221 was detected by RT-qPCR. The N-MYC mRNA and protein expression level were analyzed by RT-qPCR and Western blot, respectively. The distribution of cell cycle was tested by flow cytometry. The cell proliferation was measured by CCK8 assay. Results The recombinant vectors were verified by DNA Sanger sequencing. The results of RT-qPCR indicated that the miR-221 expression in cells transfected with miR-221 lentiviral vector as seven times as SH-SY5Y cells (P<0.01), with no difference between control and SH-SY5Y cells. Compared with SH-SY5Y cells, the mRNA and protein level of N-MYC were dramatically increased in cells transfected with miR-221 (P<0.01). The results of Flow cytometry demonstrated that miR-221 significantly decreased the G1-S checkpoint arrest (P<0.05). The results from CCK8 assay showed that overexpression of miR-221 promoted cell proliferation (P<0.01). Conclusion miR-221 may contribute to the enhancement of N-MYC and cell proliferation by rescue of G1-S checkpoint arrest in neuroblastoma SH-SY5Y cells.

Key words: Neuroblastoma, N-MYC, microRNA-221, Cell proliferation, Cell cycle