Cancer-Associated Fibroblast-Derived Exosomal circTBPL1 Regulates NSCLC Cell Stemness and Cisplatin Resistance via the miR-152-3p/Gli1 Axis

Abstract Drug resistance and cancer stem cell maintenance drive poor outcomes in non-small cell lung cancer (NSCLC), yet the role of cancer-associated fibroblast (CAF)-derived exosomal circular RNAs remains insufficiently defined. This study investigated whether CAF-derived exosomal circTBPL1 regulates NSCLC stemness and cisplatin resistance through the miR-152-3p/Gli1 axis. Exosomal circRNAs from CAFs and normal fibroblasts were profiled by high-throughput sequencing, and circTBPL1 was validated using qRT-PCR, RNase R, actinomycin D, and fluorescence in situ hybridization. Functional assays, xenograft models, dual-luciferase reporter assays, RNA immunoprecipitation, RNA pull-down, rescue experiments, and TCGA analyses were performed. circTBPL1 was enriched in CAF-derived exosomes and displayed circular RNA stability and cytoplasmic localization. CAF-derived exosomal circTBPL1 promoted NSCLC cell proliferation, migration, invasion, tumor-sphere formation, stemness marker expression, and cisplatin resistance. circTBPL1 silencing in CAFs reduced cisplatin IC50 values, inhibited resistant-cell proliferation, and suppressed xenograft growth. Mechanistically, circTBPL1 acted as a competing endogenous RNA by binding miR-152-3p, relieving repression of Gli1 and activating Hedgehog-related resistance signaling. miR-152-3p inhibition or Gli1 overexpression partially reversed circTBPL1-knockdown effects. TCGA analysis linked high Gli1 expression with poorer survival in lung adenocarcinoma, supporting circTBPL1 as a potential biomarker candidate and therapeutic target requiring further clinical validation.