c-Myc promotes pulmonary fibrosis by driving myofibroblast activation and cellular senescence

Background Idiopathic pulmonary fibrosis (IPF) is a devastating and progressive interstitial lung disease characterized by aberrant myofibroblast activation, cellular senescence, and excessive extracellular matrix (ECM) deposition. However, the precise molecular switches governing these pathogenic processes in lung fibroblasts remain incompletely understood. Although the transcription factor c-Myc has been implicated in various organ fibroses, its specific role and underlying mechanisms in pulmonary fibrosis remain largely unexplored. Here, we investigated the pathogenic role of c-Myc in IPF fibroblasts and bleomycin (BLM)-induced pulmonary fibrosis. Methods Single-cell RNA sequencing (scRNA-seq) datasets and clinical human lung tissues from IPF patients and healthy donors were analyzed to evaluate c-Myc expression patterns. In vivo , C57BL/6 mice were intratracheally administered an adeno-associated virus serotype 9 (AAV9) vector to overexpress c-Myc prior to BLM injury. Lung damage was evaluated using Micro-CT and histopathological analysis. In vitro , primary human IPF fibroblasts were transduced with lentiviral vectors for c-Myc overexpression or short hairpin RNA (shRNA)-mediated knockdown. Fibroblast activation, proliferation, migration, and senescence were assessed using RT-qPCR, Western blotting, EdU incorporation, wound-healing, transwell assays, and SA-β-gal staining. Transcriptomic alterations following c-Myc depletion were further evaluated via RNA-seq. Results scRNA-seq analysis and clinical validations revealed that c-Myc is substantially upregulated in IPF lungs and predominantly enriched in the fibroblast population. In vitro , lentiviral overexpression of c-Myc exacerbated TGF-β1-induced myofibroblast activation, hyperproliferation, migration, and ECM production. Conversely, targeted c-Myc knockdown effectively abolished these profibrotic behaviors and profoundly suppressed the cellular senescence phenotype, characterized by decreased expression of p16, p21, and p53. Mechanistically, c-Myc deficiency blocked the canonical TGF-β1/Smad2/3 signaling cascade, and RNA-seq profiling confirmed the systemic blunting of proliferation, senescence, and ECM-producing gene networks. In vivo , AAV9-mediated c-Myc overexpression significantly aggravated BLM-induced lung consolidation and structural distortion in mice. Conclusions c-Myc is significantly upregulated in IPF and functions as a critical pathogenic driver that orchestrates myofibroblast activation and cellular senescence through the TGF-β1/Smad signaling pathway. Targeted inhibition of c-Myc effectively uncouples these profibrotic responses, suggesting that the c-Myc signaling axis represents a promising translational therapeutic target for idiopathic pulmonary fibrosis.