Wnt3-mediated fibrosis and carcinogenesis of lung squamous cell carcinoma in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) increases the risk of lung squamous cell carcinoma (LUSC), yet its molecular pathogenesis remains unclear. We conducted multi-omics analysis, including single-cell RNA sequencing and digital spatial profiling, on LUSC specimens from seven patients with usual interstitial pneumonia (UIP). In UIP lung tissue, metaplastic basal cells arising from the transdifferentiation of alveolar type 2 (AT2) cells were increased. LUSC tumors arising within UIP exhibited molecular profiles and trajectory dynamics suggesting derivation from these metaplastic basal cells. Both UIP-affected tissue and associated tumors showed activation of Wnt signaling, particularly <i>WNT3</i> expression. Additionally, enrichment of the nuclear factor erythroid 2-related factor 2 (NRF2)-linked antioxidant response was observed in LUSC within UIP. Targeting Wnt/β-catenin signaling restored the sensitivity of these stress-adapted cancer cell lines to oxidative damage. These findings suggest that LUSC within UIP originates from AT2-derived metaplastic basal cells and involves aberrant Wnt3 activation, linking fibrosis to carcinogenesis and highlighting a potential therapeutic strategy.