Globulol from Alpinia oxyphylla Miq. Enhances the Pharmacological Effects of Anti-PD-1 Drugs in Combination by Reducing PD-L1 Expression in Hepatocellular Carcinoma

Globulol is a terpenoid metabolite isolated from Alpinia oxyphylla Miq. Previous studies have demonstrated that terpenoid metabolites exhibit anti-inflammatory, antioxidant, and antitumor activities. However, the exact mechanisms by which Globulol impacts HCC remain obscure.The influence of Globulol on HCC cell lines was assessed in vitro employing the CCK8, EdU cell proliferation assays, a three-dimensional tumor spheroid model, and flow cytometry. The combination effects of Globulol and anti-PD-1 was explored in an HCC and CD8+T cell co-culture model. The molecular pathways influenced by Globulol in HCC were delineated through transcriptomic sequencing, molecular docking, bioinformatics approach, cell transfection, quantitative reverse transcription-PCR, and Western blot analysis.Globulol notably decreased the viability of Huh1/Huh7 cells in a concentration-dependent manner. It was found to prompt the secretion of the chemokine CCL4 by tumor cells, enhancing the infiltration of cytotoxic CD8+T cells into the HCC microenvironment. Further research has indicated that globulol inhibits PD-L1 expression by targeting the PAK4-pAKT-STAT3 axis, improves the immunosuppressive microenvironment of HCC, and enhances the pharmacological effects in combination with Tislelizumab.These results suggest that Globulol can promote a microenvironment permissive to PD-1 blockade, thereby exerting anti-HCC activity. Hence, the combination of Globulol and PD-1 blockade may be a promising strategy for HCC treatment.