MiR-2779-x, a Key microRNA that is Related to the Tumorigenicity of the MDCK Cell Line

MDCK cells are the preferred cell line for influenza vaccine production, and the tumorigenicity of this cell line is a major concern with respect to its safety for vaccine production. However, the effect of miRNAs on the tumorigenicity of MDCK cells is poorly understood. In this study, we performed high-throughput sequencing of miRNAs in four MDCK cell lines with different degrees of tumorigenicity. Thereafter, the functions of these differentially expressed miRNAs were explored by miRNA target gene prediction, and we identified miR-2779-x as a key miRNA that is involved in the tumorigenicity of MDCK cells. Overexpression of miR-2779-x could decreased the tumorigenicity of MDCK cells in vivo and vitro. Dual luciferase binding reporter assay and Western blotting showed that miR-2779-x targeted and inhibited Bak1 protein expression. The effect of miR-2779-x on the tumorigenicity of MDCK cells in vitro was evaluated by Cell Counting Kit-8, wound healing and transwell invasion assays. Overexpression of miR-2779-x decreased cell proliferation and migration but increased cell invasion. In conclusion, we obtained evidence for the involvement of miRNAs in the tumorigenic phenotype of MDCK cells and provided novel insight into the establishment of MDCK cell lines that lack tumorigenicity.