ALKBH5 in Cancer-Associated Fibroblasts Governs an Epitranscriptomic Axis That Drives Pancreatic Cancer Metastasis.

UNLABELLED: Cancer-associated fibroblasts (CAF) are principal determinants of pancreatic ductal adenocarcinoma (PDAC) progression. CAFs can shape tumor behavior via multiple pathways, underscoring the need for a complete understanding of the regulatory mechanisms that govern CAF function. In this study, we identified N6-methyladenosine (m6A) remodeling as a hallmark of CAF activation and defined a critical role for the m6A demethylase ALKBH5 in PDAC metastasis. Activated CAFs exhibited a global reduction in m6A abundance, with ALKBH5 emerging as a key regulator of the CAF epitranscriptome. Functionally, CAF-derived ALKBH5 enhanced pancreatic cancer cell migration and invasion in vitro and promoted epithelial-mesenchymal transition-associated gene expression in tumor cells in an m6A-dependent manner. Orthotopic co-implantation models and host genetic ablation models demonstrated that ALKBH5 plays a critical role in metastatic dissemination, with minimal impact on primary tumor growth. Mechanistically, ALKBH5 enhanced the m6A-dependent translation of HSF1 in CAFs, at least in part by relieving insulin-like growth factor 2 mRNA-binding protein 3-associated translational constraints. Elevated HSF1 subsequently activated leukemia-inhibitory factor (LIF) transcription through distal enhancer elements, establishing an ALKBH5-HSF1-LIF signaling axis that mediated the prometastatic CAF-tumor cell communication. Clinically, enrichment of ALKBH5+HSF1+ CAFs independently predicted poor prognosis and was preferentially observed in metastatic PDAC. Collectively, these findings uncover a CAF-intrinsic epitranscriptomic program that drives PDAC metastasis and highlight stromal m6A regulation as a potential therapeutic vulnerability.

SIGNIFICANCE: Cancer-associated fibroblast-intrinsic ALKBH5 facilitates metastatic dissemination in pancreatic ductal adenocarcinoma via m6A-dependent HSF1-LIF paracrine signaling, uncovering a stroma-specific vulnerability with therapeutic relevance in pancreatic cancer.