PD-L1 upregulated by IGF1R via the PI3K/AKT/NF-κB axis induces sorafenib resistance in hepatocellular carcinoma.
PURPOSE Aberrant activation of insulin-like growth factor 1 receptor (IGF1R) in hepatocellular carcinoma (HCC) is closely associated with resistance to targeted therapies. However, the mechanism by which IGF1R transcriptionally upregulates programmed death-ligand 1 (PD-L1) to drive sorafenib resistance remained unclear. This study aimed to elucidate the molecular pathway through which IGF1R upregulates PD-L1 via the PI3K/AKT/NF-κB signaling cascade, thereby promoting sorafenib resistance. METHODS The regulatory network of the IGF1R-PI3K/AKT/NF-κB-PD-L1 axis was analyzed using immunohistochemistry (20 HCC clinical samples), Western blotting (THLE-2 and Huh7/Hep3B/SNU-387 cells), functional assays (CCK8, colony formation, Transwell, JC-1, Annexin V-FITC/PI), chromatin immunoprecipitation (ChIP), and dual-luciferase reporter assays. Two independent in vivo cohorts were established: Cohort 1(SCID mice bearing Huh7 xenografts, IGF1 + sorafenib (SFB)) to assess IGF1R-driven resistance; Cohort 2 (NOD-SCID mice/SNU-387, PD-L1 knockdown/overexpression ± sorafenib) to validate PD-L1 as the downstream effector. RESULTS IGF1R was significantly overexpressed in HCC. IGF1R activation increased the sorafenib IC50 by 2.3-fold and activated PI3K/AKT/NF-κB signaling. NF-κB directly bound to the PD-L1 promoter to drive its transcription, as confirmed by ChIP and dual-luciferase assays. PI3K inhibition with LY294002 blocked IGF1R-induced PD-L1 upregulation and restored sorafenib sensitivity. PD-L1 overexpression promoted HCC proliferation, migration, and cell-cycle progression while suppressing apoptosis; PD-L1 knockdown yielded opposite effects. In vivo, Cohort 1 confirmed that IGF1R activation promoted tumor growth, attenuated sorafenib efficacy, and elevated p-AKT, p-NF-κB, and PD-L1 in tumor tissues. Cohort 2 demonstrated that PD-L1 knockdown augmented sorafenib-induced tumor suppression, whereas PD-L1 overexpression blunted sorafenib efficacy, with reciprocal changes in Ki-67 and pathway phosphorylation. CONCLUSION IGF1R upregulates PD-L1 via the PI3K/AKT/NF-κB axis through direct NF-κB-mediated transcriptional activation, and PD-L1 serves as a critical downstream effector driving sorafenib resistance in HCC.