In vitro -induced cancer-associated fibroblasts-derived Exosomal miRNA-224-5p targets PTEN to reduce cisplatin (DDP) sensitivity in colorectal cancer

BACKGROUND: Cancer-associated fibroblasts (CAFs)-derived exosomes promote tumor malignancy and confer chemotherapy resistance. However, their mechanistic roles in colorectal cancer (CRC) remain incompletely understood. METHODS: Human normal colon fibroblasts were induced into CAFs using CRC cell-conditioned medium and identified by immunofluorescence. Exosomes were isolated from CAFs and characterized by Western blot, DLS analysis and cell uptake experiment. qPCR was employed to detect miRNA-224-5p expression in CAFs-derived exosomes. CCK-8 and comet assays were conducted to evaluate miRNA-224-5p's effect on cisplatin (DDP) resistance in CRC. TargetScan predicted miRNA-224-5p's downstream targets, with luciferase assays validating its interaction with PTEN. Overexpression experiments elucidated miRNA-224-5p's mechanism in DDP resistance via PTEN regulation. RESULTS: miRNA-224-5p was highly expressed in CAFs-derived exosomes. Functional assays revealed that exosomal miRNA-224-5p from CAFs promoted DDP resistance in CRC cells while suppressing DNA damage and apoptosis. Mechanistically, PTEN was identified as a direct target of miRNA-224-5p, through which it enhanced DDP resistance. CONCLUSION: This study demonstrates that CAFs-derived exosomal miRNA-224-5p promotes DDP resistance in CRC by targeting PTEN, suggesting miRNA-224-5p as a potential therapeutic target for improving CRC treatment outcomes. Insight box MiRNA-224-5p was highly expressed in CAFs-derived exosomes. Functional assays revealed that exosomal miRNA-224-5p from CAFs promoted DDP resistance in CRC cells while suppressing DNA damage and apoptosis. PTEN was identified as a direct target of miRNA-224-5p, through which it enhanced DDP resistance.