Fig. 6: Targeting SQLE enzyme enhances anti-tumor immunity by acting on the oxLDL-TREM2⁺TAM axis.

A Venn diagram shows the overlapping metabolism genes that are upregulated in the tumor and the metabolism archetype (left). Heatmap depicts prognostic significance of top genes in five primary HCC cohorts using an univariate Cox regression model (right). B Correlation between cancer cell SQLE expression and TREM2⁺TAM signatures of TAMs in snRNA-seq (n = 12, left) and public scRNA-seq dataset (n = 10, right). C Representative images showing the expression of SQLE, oxLDL, TREM2, SPP1, and CD68 in SQLE-positive and SQLE-negative tissue spots from HCC TMA. Representative cells that denote the presence of TREM2⁺SPP1⁺TAMs are indicated by arrowheads. Scale bar, 50 μm (left). Composition of oxLDL-high or oxLDL-low spots in SQLE-positive (n = 110) and SQLE-negative (n = 126) spots. Quantification of TREM2⁺SPP1⁺TAMs in SQLE-positive and SQLE-negative spots (right). D Violinplot shows SQLE expression in normal/malignant hepatocytes from indicated groups, with two-tailed Wilcoxon-test statistics. E Representative images showing SQLE expression in ICB-NR and ICB-R tumors. Scale bar, 100 μm (left). Quantification of SQLE fluorescence in the tumor region of ICB-NR (n = 6) and ICB-R (n = 4) tumors (right). F, G NADP⁺/NADPH ratio, ROS (F), lipid peroxidation levels (G) of shNC or shSqle cancer cells. H Supernatant oxLDL levels of shNC or shSqle cancer cells cultured with DMEM plus 10% mouse serum for 48 h. I Flow cytometry shows Dil-oxLDL uptake in shNC or shSqle cancer cells ± SSO (100 μM). J Schematic of the orthotopic models. K Tumor volume of shNC or shSqle tumors (n = 6 mice). L Concentration of oxLDL in TIF isolated from shNC or shSqle tumors (n = 6 mice). M, N Flow cytometry of TREM2, SPP1 expression in TAMs (M) and IFNγ expression in tumor-infiltrating CD8⁺T cells (N) (n = 6 mice). O Schematic of the orthotopic models and treatment. P Tumor volume of shNC or shSqle tumors treated with isotype or anti-PD1 (n = 6 mice). Q, R Flow cytometry of TREM2, SPP1 expression in TAMs (Q) and GZMB, IFNγ expression in tumor-infiltrating CD8⁺T cells (R) (n = 6 mice). S Schematic of experimental treatment in spontaneous HCC model. T Tumor burden in mice treated with isotype or anti-PD-1 and Terbinafine or DMSO (n = 6 mice). U, V Flow cytometry of TREM2, SPP1 expression in TAMs (U) and GZMB expression in tumor-infiltrating CD8⁺T cells (V) (n = 6 mice). Data represent the mean ± SD, n = 3 biological replicates in (F right), H, I, n = 5 biological replicates in (F left), n = 6 biological replicates in (G). Statistical significance was determined by two-tailed Wald test (A), two-tailed Wilcoxon signed rank test (D), two-tailed Fisher’s exact test (C middle), two-tailed unpaired t test (C right, E–I, K–N, P–R, T–V), and two-tailed one-sample t test (B). Schematics in J, O, and S were created in BioRender. Chu, T. (2025) https://BioRender.com/r2v4jgs. Source data is provided as a Source Data file.