Huh7-Luc | Inhibiting SOAT1 Remodels Lipid Metabolism and Enhances Immunotherapy Efficacy in Liver Cancer
Hepatocellular carcinoma (HCC) is highly prevalent and heterogeneous, facing bottlenecks in conventional therapies and low response rates to immunotherapy. Lipid metabolic reprogramming and immune evasion are recognized as key hallmarks, and the cholesterol esterification enzyme SOAT1 is highly expressed in HCC, though its function remains to be fully elucidated.This research, integrating multi-omics, organoids, and immunocompetent mouse models, demonstrated that SOAT1 deficiency blocks cholesterol esterification, leading to saturated fatty acid accumulation, ROS, and ER stress, which activates NF-κB signaling, upregulates chemokines like CXCL16, recruits CD11c+ antigen-presenting cells, and enhances CD8+ T cell cytotoxicity. The repurposed drug Avasimibe, by inhibiting SOAT1, synergizes with PD-1 blockade to significantly reduce tumor burden, offering a novel metabolic-immune combination strategy for liver cancer.
Article Highlights
1) SOAT1 is significantly highly expressed in HCC and correlates with poor prognosis.
Figure 1 shows a three-step screening process ("cell-organoid-immune migration") that identified SOAT1. RNA-seq and qPCR showed that SOAT1 was significantly upregulated in tumor tissues from both the TCGA-LIHC and HKU-QMH cohorts, with IHC validating high protein expression; high expression groups had shorter overall survival and were positively correlated with vascular invasion, advanced TNM stage, and copy number amplification, establishing its pro-tumor and prognostic value.
Figure 1
2) SOAT1 deficiency significantly inhibits HCC growth and metastasis in vitro and in vivo.
In Figure 2, inhibiting SOAT1 with shRNA or Avasimibe reduced cell and patient-derived organoid (PDO) proliferation by 40-70%. In Huh7-Luc, Hepa1-6, and patient-derived orthotopic xenograft (PDOX) models, the knockdown/inhibition groups showed significantly reduced bioluminescence, tumor weight, and lung metastasis; reintroducing wild-type SOAT1 rescued the phenotype, while a catalytically dead mutant had no effect, proving the enzyme-activity-dependent tumor suppression.
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Figure 2
3) Inhibiting SOAT1 remodels cholesterol and long-chain fatty acid metabolism, inducing oxidative and ER stress.
Figure 3 shows that SOAT1-KD blocked cholesterol esterification, downregulated synthesis genes, and reduced lipid droplets; simultaneously, free fatty acids such as C16:0 and C18:0 increased 2-4 fold, leading to elevated ROS, lipid peroxidation, and ER dilation, with significant upregulation of GRP78/XBP1s/CHOP; NAC or exogenous palmitic acid experiments confirmed that fatty acid accumulation is the initiating factor for ROS and ER stress.
Figure 3
4) SOAT1 deficiency activates NF-κB1 signaling via the saturated fatty acid-IKKβ axis.
Figure 4 shows RNA-seq indicating enrichment of NF-κB inflammatory genes; both SOAT1-KD and palmitic acid stimulation increased p-IKKβ/p-IκBα levels and promoted NF-κB1 nuclear translocation; NAC inhibition of ROS blocked this activation, and co-knockdown of IKKβ also prevented NF-κB reporter activity, demonstrating the link from SOAT1 deficiency → fatty acid accumulation → ROS → IKKβ/NF-κB pathway, connecting metabolism and inflammation.
Figure 4
5) SOAT1 deficiency drives a chemokine cascade via NF-κB1 to enhance monocyte migration.
In Figure 5, secretome analysis revealed that conditioned media from SOAT1-KD cells had 2-4 fold higher levels of CXCL16, CXCL12, and CX3CL1; the promoters of these three genes contain NF-κB binding sites, and reintroducing wild-type SOAT1 or co-knocking down IKKβ suppressed their expression. THP-1 migration assays showed that neutralizing CXCL16 or inhibiting CXCR4 weakened the chemotactic effect, demonstrating that the NF-κB-driven three-factor axis synergistically recruits immune cells.
Figure 5
6) SOAT1 knockout remodels the immune microenvironment and increases CD11c+ antigen-presenting cell infiltration.
In the Hepa1-6 orthotopic model in Figure 6, SOAT1-KD changed the distribution of CD45+ cells from the tumor periphery to diffuse intratumoral infiltration; flow cytometry showed CD11c+ cells increased to 14%, co-expressing MHC-I/II; in the c-MycOE/Trp53KO model, sgSoat1 also increased CD11c+/F4/80+/MHC-II+ triple-positive clusters, which were rare in non-tumor liver. Co-culture and IKKβ inhibitor experiments confirmed that chemotactic signals directly promote myeloid infiltration and antigen presentation.
Figure 6
7) The tumor-immune crosstalk induced by SOAT1 deficiency promotes pro-inflammatory gene expression and upregulation of adhesion molecules.
In Figure 7, after co-culturing THP-1 cells with KD tumor cells, THP-1 cells showed an M1 bias (with increased CXCL9/10); on the tumor cell side, adhesion molecules such as C3 and ICAM-1 were upregulated >3 fold, and their promoter NF-κB reporter activity was enhanced; co-knockdown of IKKβ or NAC treatment suppressed their expression. These results indicate that SOAT1 deficiency simultaneously upregulates chemokines and adhesion ligands via NF-κB, amplifying immune recruitment and retention.
Figure 7
8) SOAT1 knockout enhances CD8+ T cell cytotoxicity and synergizes with anti-PD-1 therapy.
In Figure 8, the Soat1 knockout model showed that the intratumoral CD8+ T cell proportion increased to 18%, while the PD-1+ subpopulation decreased; in vitro, OT-I CD8+ T cell killing of KD Huh7 cells increased from 36% to 72%. In the c-MycOE/β-catenOE model, Avasimibe combined with anti-mouse PD-1 reduced bioluminescence signals by >80%, with liver weights nearing normal; Bliss analysis yielded Q>1.15, confirming that SOAT1 inhibition enhances CD8+ T cell function and synergizes with immune checkpoint blockade.
Figure 8
