Objective To systematically elucidate the molecular mechanisms and core targets underlying the anti-hepatocellular carcinoma (HCC) effects of icariin through integrated network pharmacology and experimental validation.

Methods Potential targets of icariin were screened using the PubChem database and SwissTargetPrediction platform, followed by intersection analysis with HCC-related genes from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to characterize the biological functions of candidate targets. Key genes were identified using the random survival forest algorithm, and their associations with the tumor microenvironment were evaluated through immune infiltration analysis. Molecular docking was employed to predict the binding affinity between icariin and its core targets, which was subsequently validated by in vitro enzyme inhibition assays. Functional targets were determined through overexpression experiments in HepG2 cells, and mechanistic investigations were conducted using Western blot and co-immunoprecipitation techniques. In vivo anti-tumor efficacy was evaluated using a subcutaneous HepG2 xenograft mouse model by monitoring tumor volume progression and endpoint tumor weight, and the impact of polo-like kinose 1 (PLK1) overexpression on icariin-mediated tumor growth inhibition was assessed.

Results  Network pharmacology analysis identified 36 common targets between icariin and HCC, which were primarily enriched in hypoxia-inducible factor-1 (HIF-1), phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT), and forkhead box O (FoxO) signaling pathways. Among these, PLK1, ATP binding cassette subfamily C member 1 (ABCC1), and matrix metallopeptidase 3 (MMP3) were identified as key genes, with their high expression significantly associated with poor patient prognosis (P < 0.0001, P = 0.004, and P = 0.03, respectively). Immune infiltration analysis revealed significant correlations between these three genes and various immune cell types, suggesting their involvement in modulating the tumor immune microenvironment. Molecular docking predicted stable binding between icariin and these targets, and in vitro enzymatic assays confirmed that icariin (20 µmol/L) exhibited the highest inhibitory rate against PLK1 (49.67% ± 4.19%), significantly greater than that against ABCC1 (24.33% ± 3.40%) and MMP3 (38.00% ± 3.06%). Functional validation demonstrated that PLK1 overexpression reversed icariin-mediated inhibition of HepG2 cell proliferation (P < 0.05), whereas ABCC1 or MMP3 overexpression showed no such effect, indicating PLK1 as the primary functional target of icariin. Mechanistic studies revealed that icariin specifically reduced PLK1 phosphorylation levels and disrupted its interaction with forkhead box M1 (FoxM1). In vivo experiments confirmed that PLK1 overexpression significantly attenuated icariin-induced suppression of tumor growth in xenograft mice (P < 0.001).

Conclusion PLK1 is a critical target mediating the anti-HCC effects of icariin through inhibition of the PLK1-FoxM1 axis, providing a mechanistic basis for the clinical development of icariin as an HCC therapeutic agent.