Cancer-Associated Fibroblasts Promote Imatinib Resistance in Gastrointestinal Stromal Tumors through PGK1-Mediated Metabolic Reprogramming

Gastrointestinal stromal tumors (GISTs), the most common sarcomas of the gastrointestinal tract, are primarily driven by c-KIT or PDGFRA mutations that activate downstream signaling pathways, including PI3K/AKT/mTOR. While imatinib, a first-line tyrosine kinase inhibitor (TKI), is initially effective, resistance develops in ~50% of patients within 20 months. Second- and third-line TKIs, such as sunitinib and regorafenib, provide limited benefits, highlighting the urgent need to address resistance mechanisms. Previous research has predominantly focused on genetic drivers of resistance and overlooked the role of the tumor microenvironment (TME). Here, we identified a role for cancer-associated fibroblasts (CAFs) in driving imatinib resistance. Specifically, TGF-β1 secreted by CAFs amplified CCN2/Rack1 signaling. The CCN2/Rack1 axis activated PI3K/AKT signaling to induce phosphorylation and mitochondrial translation of PGK1, promoting metabolic reprogramming that supported tumor survival and drug resistance. Co-culture models and single-cell RNA sequencing revealed distinct CAF subtypes and showed that CAF-secreted TGF-β1 enhanced glycolysis and inhibited the tricarboxylic acid (TCA) cycle, fueling GIST progression and secondary resistance. Inversely, CCN2 secreted by GIST cells promoted TGF-β1 production in CAFs. These findings uncover a TGF-β1/CCN2/Rack1/PGK1 mechanism linking CAF-mediated metabolic reprogramming to imatinib resistance in GISTs. Targeting CAF-GIST interactions and key metabolic pathways presents a promising therapeutic strategy.