Hepatocytes promote liver metastasis of pancreatic cancer by providing serine.

The liver is the primary site of metastasis in pancreatic ductal adenocarcinoma (PDAC), and liver metastases are a major cause of mortality1,2. Nutrient availability in the metastatic niche influences colonization efficiency; however, the metabolic heterogeneity of disseminated tumour cells can also reshape the local microenvironment3-5. Loss of phosphoglycerate dehydrogenase (PHGDH), the rate-limiting enzyme in de novo serine biosynthesis, is observed in nearly 40% of PDACs, and renders these cells dependent on exogenous serine (exSer)6. Although a neuron-tumour metabolic cross-talk supports exSer-dependent PDAC cells at the primary site6, it remains unclear how these cells adapt to the metastatic liver niche. Here we show that exSer-dependent PDAC cells reprogram neighbouring hepatocytes through a CXCL5-CXCR2 axis. Activation of CXCR2 in hepatocytes promotes PI3K-AKT signalling, leading to the sequestration of FOXO3A in the cytoplasm and derepression of PHGDH transcription, thereby enhancing serine production in hepatocytes. This hepatocyte-derived serine supports the outgrowth of exSer-dependent PDAC liver metastases. Accordingly, genetic or pharmacological inhibition of individual nodes within the CXCL5-CXCR2-PI3K-AKT-FOXO3A axis, or hepatocyte-specific deletion of Phgdh or Cxcr2, markedly reduces the liver-metastasis burden in mice and prolongs survival, particularly when dietary serine is restricted. Our findings reveal a cancer cell-hepatocyte metabolic cross-talk and identify therapeutic targets for exSer-dependent PDAC liver metastases.