A novel EGR1-driven GLUL/mTOR axis regulates macropinocytosis-mediated crosstalk in pancreatic stellate cell-cancer metastasis.

BACKGROUND: Pancreatic cancer liver metastasis relies on crosstalk between pancreatic stellate cells (PSCs) and cancer cells, yet the role of transcriptional regulation in this interplay, particularly via macropinocytosis, remains unclear. Here, we aimed to explore a novel EGR1-driven pathway linking PSC function to cancer cell nutrient acquisition and liver metastasis.

METHODS: Single-cell RNA sequencing (scRNA-seq) was performed on human pancreatic cancer tissues to identify key regulators of PSC-cancer cell crosstalk. ChIP, EMSA, luciferase reporter assays, and western blotting were used to validate transcriptional regulation of GLUL by EGR1. Functional assays included cell proliferation, migration, invasion, and macropinocytosis analyses in co-culture systems. In vivo studies utilized a murine model of pancreatic cancer liver metastasis to assess the impact of the EGR1-GLUL/mTOR axis on metastasis.

RESULTS: scRNA-seq identified EGR1 as a transcription factor enriched in PSCs, with strong co-expression of GLUL and mTOR pathway genes. EGR1 directly bound the GLUL promoter, promoting its transcription and activating mTOR signaling. This axis suppressed PSC activation (reduced α-SMA expression). EGR1 over-expressed PSCs inhibited pancreatic cancer cell macropinocytosis, leading to impaired nutrient uptake, reduced ATP production, and suppressed malignant behaviors (proliferation, migration, invasion). Additionally, the EGR1-GLUL/mTOR axis reduced liver metastasis in vivo.

CONCLUSION: The EGR1-driven GLUL/mTOR axis in PSCs suppresses pancreatic cancer progression by inhibiting PSC activation, reducing cancer cell macropinocytosis, and restraining metastasis. This axis represents a promising therapeutic target for disrupting PSC-cancer cell crosstalk in pancreatic cancer.