Modulation of tumor-derived exosomes and reprogramming of cancer-associated fibroblasts for colorectal cancer therapy.

Hypoxia is pervasive within the solid tumor microenvironment (TME), reshaping it through exosome release. As the main component of the tumor stroma, fibroblasts influence TME remodeling and tumor progression. Recent advances in targeting tumor-derived exosomes offer promising opportunities for innovative colorectal cancer (CRC) therapies. Here, we found that exosomes induced by hypoxia in CRC cells (H-Exo) can promote the activation of normal tissue-associated fibroblasts (NAFs) into cancer-associated fibroblasts (CAFs) phenotype, with a stronger effect compared to normoxic exosomes (N-Exo). Machine learning analysis identified HIF1A-AS2, induced by hypoxic tumor-derived exosomes, as a promising prognostic lncRNA in CRC. Pan-cancer and scRNA-seq analyses showed that high HIF1A-AS2 expression was characterized by hypoxia, angiogenesis, immunosuppression (e.g., CAFs), TGF-β, and fibroblast-CD44 interactions in CRC. HIF1A-AS2 expression progressively increased along pseudotime, shifting from early immune activation to late-stage extracellular matrix (ECM) organization, vascular niche formation, and fibroblast activation. HIF1A-AS2 in H-Exo was a key factor in the transformation of NAFs into CAFs. Exosomal HIF1A-AS2 sequesters miR-33, thereby derepressing HIF-1α, activating Notch1/ERK signaling, and upregulating angiogenic and matrix-remodeling factors (e.g., VEGF, MMP-7, and MMP-9). Further research revealed that exosomes with silenced HIF1A-AS2 or overexpressed miR-33 could inhibit CAF infiltration, tumor cell proliferation, angiogenesis, and ECM reorganization in xenografts, ultimately suppressing tumor growth. These findings highlight that simultaneously blocking tumor exosome-driven fibroblast activation and the HIF1A-AS2/miR-33/HIF-1α axis may serve as a promising therapeutic avenue for CRC intervention.