Shared immune perturbations in hepatocellular carcinoma-depression comorbidity and synergistic immunotherapeutic effects of fluoxetine combined with anti-PD-1.

BACKGROUND

Hepatocellular carcinoma (HCC) often coexists with depression, elevating patient mortality by 39%. The tryptophan metabolic axis bridges tumor and neuropsychiatric immune dysfunction, yet the immunometabolic crosstalk underlying HCC-depression comorbidity remains poorly defined, and reliable combinatorial immunotherapies are absent.

METHODS

We integrated public multi-omics datasets including TCGA, GEO, eQTLGen and FinnGen, and performed two-sample MR as well as genetic colocalization analyses to screen hub genes associated with HCC-depression comorbidity. GSEA/GSVA, single-cell and spatial transcriptomics were adopted to dissect gene expression and perturbed tryptophan immune pathways. In silico docking predicted fluoxetine binding to BTN3A3, GLCE and RBCK1. A Hepa1-6/CUMS comorbid mouse model combined with targeted tryptophan LC-MS metabolomics, flow cytometry and ELISA was used to verify combined therapeutic effects and tissue molecular alterations.

RESULTS

Seven overlapping risk genes for HCC and depression were identified. BTN3A3, GLCE and RBCK1 reached strict colocalization thresholds (SNP.PP.H4 > 0.90) and were predominantly expressed in T cells and M2 macrophages linked to tryptophan metabolism. Fluoxetine displayed stable binding affinity with all three hub proteins via molecular simulation. In vivo assays proved fluoxetine plus anti-PD-1 restrained tumor progression, alleviated depression-like phenotypes, normalized tissue GLCE/RBCK1 levels and restored disordered tryptophan metabolism and immunosuppressive microenvironment in comorbid mice.

CONCLUSIONS

This work characterizes tryptophan-mediated immune disturbance in HCC-depression comorbidity. GLCE and RBCK1 correlate with comorbid immunometabolic disorders. Fluoxetine combined with anti-PD-1 exerts synergistic immunoregulatory effects by reshaping tryptophan-related immune homeostasis, offering a preclinical metabolic immunotherapy strategy for concurrent HCC and depression.