To detect the expression levels of miR-4458 and its target protein BZW2 in hepatocellular carcinoma (HCC) and to evaluate its effects on the proliferation, migration and invasion of HCC cells.

The serum samples under fasting and HCC tissue samples (HCC group) were collected from 247 HCC patients admitted to No.900 Hospital of Joint Logistic Support Forces of PLA from January 2019 to December 2020, and serum samples under fasting from 200 healthy volunteers were collected in the control group. In the HCC group, 153 patients were male and 94 female, aged from 35 to 71 years, with a median age of 49 years. In the control group, 120 patients were male and 80 female, aged from 30 to 70 years, with a median age of 41 years. The informed consents of all patients were obtained and the local ethical committee approval was received. The expression levels of miR-4458 and BZW2 mRNA in two groups were detected by real-time fluorescent quantitative PCR. The expression level of BZW2 protein in HCC and adjacent tissues was measured by Western blot. The association between BZW2 mRNA expression in HCC tissues and clinicopathological features of HCC patients was analyzed. The interaction between miR-4458and BZW2 was predicted by bioinformatics analysis and validated by dual luciferase reporter assay. Human hepatoma cell line HepG2 was cultured and transfected. The effect of regulating miR-4458 expression on the proliferation, migration and invasion of HepG2 cells was evaluated by CCK-8 and Transwell assay.

The average relative expression level of serum miR-4458 in HCC patients was 0.85±0.23, significantly lower than 1.06±0.30 in the control group (t=-7.886, P<0.05). The relative expression level of miR-4458 in HCC tissues was 0.77±0.27, significantly lower than 1.23±0.35 in the adjacent tissues (t=-12.646, P<0.05). The relative expression of serum BZW2 mRNA in the HCC group was 1.67±0.44, significantly higher than 1.13±0.29 in the control group (t=13.674, P<0.05). The relative expression level of BZW2 mRNA in HCC tissues was 1.98±0.31, significantly higher than 1.27±0.30 in adjacent tissues (t=16.537, P<0.05). The relative expression of BZW2 protein in HCC tissues was 1.57±0.44, significantly higher than 0.83±0.38 in adjacent tissues (t=16.483, P<0.05). The relative expression of BZW2 mRNA in HCC tissues was correlated with tumor diameter, tumor encapsulation, microvascular invasion and tumor differentiation (t=-8.208, -13.248, -7.981, 7.145; P<0.05). The mutual targeting relationship between miR-4458 and BZW2 was predicted by bioinformatics analysis and validated by dual luciferase reporter assay. The relative expression of BZW2 protein was 1.95±0.24 in HepG2 cells transfected with miR-4458 inhibitor, significantly higher than 0.43±0.11 in those transfected with miR-4458 mimics (LSD-t=3.384, P<0.05). The proliferation, migration and invasion capabilities of HepG2 cells were up-regulated at 24 h, 48 h and 72 h after transfection with miR-4458 inhibitor.

The miR-4458 is lowly expressed, whereas BZW2 is highly expressed in HCC patients. Down-regulating miR-4458 expression through miR-4458 targeting BZW2 can promote the proliferation, migration and invasion of HCC cells, and it may be associated with poor prognosis of HCC patients.