Baicalin promotes anti-tumor immunity in hepatocellular carcinoma through HIF-1α/Lactate/CXCL9 axis

Low immune response is a hallmark of several solid tumors, including hepatocellular carcinoma (HCC), highlighting the urgent need for effective immunotherapeutic strategies. Baicalin, a bioactive ingredient derived from traditional Chinese medicine, has exhibited significant anti-tumor activity in various cancer types, yet its effects on anti-tumor immunity remain largely unclear. In this study, we investigated the immunomodulatory role of baicalin in HCC and elucidated its underlying mechanisms. Utilizing a Hepa1-6 subcutaneous tumor model, we observed that baicalin significantly suppressed tumor growth, accompanied by increased CD8⁺ T cell infiltration and elevated secretion of TNF-α and IFN-γ. RNA-sequencing analysis revealed marked enrichment of chemokine pathways, notably with a pronounced upregulation of CXCL9 following baicalin treatment. Importantly, shRNA-mediated knockdown of CXCL9 substantially abrogated baicalin's anti-tumor effects and reduced CD8⁺ T cell infiltration. Integrated metabolomics analysis and lactate inhibition assays further identified lactate as a key regulator of CXCL9 expression. Mechanistically, we demonstrated that HIF-1α, a central regulator of lactate production, is a direct target of baicalin. Baicalin treatment suppressed HIF-1α expression both in vivo and in vitro, corresponding with decreased lactate levels. Conversely, HIF-1α overexpression increased lactate production and inhibited CXCL9 expression. Collectively, our findings reveal that baicalin enhances anti-tumor immunity in HCC through the HIF-1α/lactate/CXCL9 axis, highlighting baicalin as a promising therapeutic candidate for HCC immunotherapy.