Gastrointestinal stromal tumors (GIST), 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. Whereas imatinib (IM), 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. In this study, we identified a role for cancer-associated fibroblasts (CAF) in driving IM resistance. Specifically, TGFβ1 secreted by CAFs amplified cellular communication network factor 2 (CCN2)/receptor for activated C kinase 1 (Rack1) signaling. The CCN2/Rack1 axis activated PI3K/AKT signaling to induce phosphorylation and mitochondrial translation of phosphoglycerate kinase 1 (PGK1), promoting metabolic reprogramming that supported tumor survival and drug resistance. Coculture models and single-cell RNA sequencing revealed distinct CAF subtypes and showed that CAF-secreted TGFβ1 enhanced glycolysis and inhibited the tricarboxylic acid cycle, fueling GIST progression and secondary resistance. Inversely, CCN2 secreted by GIST cells promoted TGFβ1 production in CAFs. These findings uncover a TGFβ1/CCN2/Rack1/PGK1 mechanism linking CAF-mediated metabolic reprogramming to IM resistance in GISTs. Targeting CAF–GIST interactions and key metabolic pathways presents a promising therapeutic strategy. Significance: Cross-talk between cancer-associated fibroblasts and cancer cells promotes metabolic and tumor microenvironmental reprogramming that drives imatinib resistance in gastrointestinal stromal tumors, providing potential targets to overcome resistance and improve therapeutic outcomes.

The cancer stem cells are a rare group of self-renewable cancer cells capable of the initiation, progression, metastasis and recurrence of tumors, and also a key contributor to the therapeutic resistance. Thus, understanding the molecular mechanism of tumor stemness regulation, especially in the gastrointestinal (GI) cancers, is of great importance for targeting CSC and designing novel therapeutic strategies. This review aims to elucidate current advancements in the understanding of CSC regulation, including CSC biomarkers, signaling pathways, and non-coding RNAs. We will also provide a comprehensive view on how the tumor microenvironment (TME) display an overall tumor-promoting effect, including the recruitment and impact of cancer-associated fibroblasts (CAFs), the establishment of an immunosuppressive milieu, and the induction of angiogenesis and hypoxia. Lastly, this review consolidates mainstream novel therapeutic interventions targeting CSC stemness regulation.

CCN2 regulates PGK1 Thr302 phosphorylation and metabolic reprogramming in GIST cells

Clinicopathological characteristics of 116 GIST patients undergoing surgery in TMA

Validation of CCN2 expression in TMA

Validation of CCN2 overexpression/knockdown efficiency and its effects on imatinib sensitivity in GIST cells