Objective:To evaluate the effect of U2 small nuclear RNA auxiliary factor 2 (U2AF2) expression on the proliferation and migration of hepatocellular carcinoma and its relationship with prognosis.Methods:The expression level of U2AF2 in HCC cell lines (HepG2, Hep3B, Huh-7 and HCCLM9) and normal liver cell LO2 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The short hairpin RNA (shRNA) mediated by lentivirus was employed to knock down the expression of U2AF2 in HCC cells (shU2AF2-1 and shU2AF2-2 were assigned into the experimental group and sh-NC as the control group). The proliferation and migration capability of HCC cells in the shU2AF2-1 and sh-NC groups were evaluated by CCK-8 assay and wound healing assay, respectively. The expression levels of mammalian target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR) in HCC cells in the shU2AF2-1 and sh-NC groups were measured by Western blot. Regarding bioinformatics analysis, the expression level of U2AF2 in HCC and its relationship with prognosis were analyzed by using UALCAN and Kaplan-Meier Plotter databases, respectively. The expression profile of HCC was downloaded from The Cancer Genome Atlas (TCGA) database. The signal pathways of U2AF2 involved in HCC were analyzed by Gene Set Enrichment Analysis (GSEA). Multi-group comparison was analyzed by one-way ANOVA. Two-group comparison was conducted by LSD-t or t test.Results:TCGA database analysis showed that the expression level of U2AF2 mRNA in HCC tissues was significantly higher than that in adjacent normal liver tissues (P<0.05), and the expression level of U2AF2 mRNA was up-regulated with the increase of HCC grade (P<0.05). Kaplan-Meier plotter database analysis revealed that the overall survival and recurrence-free survival rates of patients with high expression of U2AF2 were significantly lower than those of their counterparts with low expression (HR=1.86, 1.85; P<0.05). GSEA analysis indicated that high expression of U2AF2 was closely correlated with the mTOR signaling pathway, and the normalized enrichment score (NES) was 2.113 (P<0.05).qRT-PCR showed that the expression level of U2AF2 mRNA in HepG2, Hep3B, Huh-7 and HCCLM9 cells was significantly higher than that in normal liver cell LO2, with the highest expression level in HCCLM9 cells (F=26.003, P<0.05). In the shU2AF2-1 and shU2AF2-2 groups, the average relative expression levels of U2AF2 mRNA in HCCLM9 cells were 0.27±0.09 and 0.41±0.13, significantly lower than 1.02±0.06 in the sh-NC group (LSD-t=-7.643, -6.220; P<0.05). CCK-8 assay showed that compared with the sh-NC group, the proliferation capability of HCCLM9 cells was significantly lower in the shU2AF2-1 group (t=-5.381, P<0.05). Wound healing assay found that the migration capability of HCCLM9 cells in the shU2AF2-1 group was significantly lower than that in the sh-NC group (t=-7.903, P<0.05). Western blot showed that the expression level of p-mTOR of HCCLM9 cells in the shU2AF2-1 group was significantly lower than that in the sh-NC group, whereas there was no significant difference in the expression level of mTOR between two groups.Conclusions:U2AF2 is highly expressed in HCC. High expression of U2AF2 is correlated with poor prognosis of HCC patients. U2AF2 can promote the proliferation and migration of HCC cells probably by activating the mTOR signaling pathway.
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