Cancer-associated fibroblast-derived vascular endothelial growth factor a promotes gastric cancer organoid growth and chemotherapy resistance via paracrine signaling.

BACKGROUND: Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment and can influence tumor progression and therapeutic response. However, whether functional heterogeneity of CAFs contributes to 5-fluorouracil (5-FU) resistance in gastric cancer remains unclear. METHODS: Patient-derived organoids (PDOs) and matched CAFs were established from gastric cancer specimens and cocultured using a Transwell noncontact system. The effects of CAFs on PDO growth and chemotherapy response were evaluated. Candidate secreted factors were analyzed by qRT-PCR and ELISA. Gain- and loss-of-function experiments, together with transcriptomic and protein analyses, were performed to investigate the underlying mechanisms. A CAF-containing xenograft model was established to evaluate the therapeutic effects of VEGFA blockade combined with 5-FU treatment in vivo. RESULTS: CAFs derived from different patients exhibited marked functional heterogeneity in regulating PDO growth and chemotherapy response. A VEGFA-associated functional CAF state significantly promoted PDO proliferation and enhanced resistance to 5-FU. Vascular endothelial growth factor A (VEGFA) was identified as a key secreted factor that was significantly upregulated in these growth-promoting CAFs. Exogenous VEGFA recapitulated the pro-growth and anti-apoptotic effects observed, whereas VEGFA blockade attenuated CAF-mediated chemoprotective effects and enhanced PDO sensitivity to 5-FU. In vivo, bevacizumab improved the response of CAF-containing tumors to 5-FU treatment, supporting the therapeutic relevance of targeting CAF-derived VEGFA. These effects were driven by the activation of the PI3K/AKT-mTOR survival pathway in PDOs. CONCLUSION: A VEGFA-associated functional CAF state promotes gastric cancer organoid growth and chemoresistance through paracrine signaling, highlighting the CAF-VEGFA axis as a potential therapeutic target.