Fig. 4: Functionally reprogrammed hepatocytes promote SAA2 expression through PPARγ-mediated metabolic reprogramming.

A Gene set enrichment analysis (GSEA) showing significant downregulation of the PPAR signaling pathway in Hepa-C11 hepatocytes. Enrichment score (ES), normalized enrichment score (NES), P value, and false discovery rate (FDR, Benjamini–Hochberg corrected) are indicated (n = 4 mice). B Scaled heatmap of key PPAR pathway–related genes across hepatocyte subclusters (Hepa-C1 to Hepa-C12), with cell numbers shown above each column (n = 4 mice). C Heatmap of metabolic pathway activities across hepatocyte subclusters (Hepa-C1 to Hepa-C12). Color scale represents relative pathway activity, and the red box highlights the distinctive metabolic pattern of Hepa-C11 (n = 4 mice). D Western blot of PPAR isoforms (α, β/δ, γ) in fractionated AML12 hepatocytes following co-culture with CRC cells (Vector vs. KIAA1199) (n = 3 independent experiments). E Western blot analysis of PPARγ and SAA2 in liver tissues from orthotopic tumor-bearing mice treated with or without rosiglitazone (Rog, 10 μg/kg/day) and sacrificed on day 14 (n = 3 independent experiments). F Spatial transcriptomic maps showing SAA2 (left) and PPARG (right) expression in two colorectal liver metastasis (CRLM) samples. Red dashed lines delineate tumor boundaries. G Predicted PPARγ binding motifs (P1 and P2) within the mouse Saa2 promoter region (−100 bp to +2000 bp). H Dual-luciferase reporter assays in AML12 cells using wild-type or mutant Saa2 promoter constructs. Mutation of the P2 site abolished PPARγ-mediated repression of Saa2 (n = 3 independent experiments, Student’s t test). I ChIP-qPCR confirming PPARγ binding to the Saa2 promoter in AML12 cells (n = 3 independent experiments, Student’s t test). J Schematic of the triple co-culture system (CRC + AML12 + Neutrophils) treated with Rog (10 μM). K ELISA quantification of SAA2 in co-culture supernatants (n = 3 mice, Student’s t test). L–M Flow cytometry quantification of Egr1⁺ neutrophils generated in the co-culture system using C57BL/6 (L) and BALB/c (M) neutrophils (n = 3 mice, Student’s t test). N Schematic of Rog treatment in the dual-tumor mouse model. O Representative gross liver and H&E images (n = 4 mice). Scale bars: 2 mm (gross) and 2 mm (histology). P–R Quantification of liver metastatic area (P), metastatic nodules (Q), and liver weight (R; n = 4 mice, Student’s t test). S Kaplan–Meier survival curves comparing KIAA1199 and KIAA1199+Rog groups (n = 10 mice, log-rank test). FACS gating strategies are shown in Supplementary Fig. 5G. Where applicable, all statistical tests are two-sided. Data are presented as mean ± s.d. Source data and exact p values are provided as a Source Data file.