Targeting the Snail1-ATGL-Ferroptosis-EMT Axis via AKT-GSK3β Signaling: Low-Dose Colchicine Attenuates Idiopathic...

The mechanisms underlying colchicine's (COL's) anti-fibrotic effects in idiopathic pulmonary fibrosis (IPF) remain unclear. Ferroptosis-associated redox imbalance and epithelial-mesenchymal transition (EMT) are well-recognized central drivers of IPF progression, yet the upstream regulatory mechanisms linking redox homeostasis to ferroptotic vulnerability remain incompletely elucidated.

This study aimed to clarify the effects and mechanisms of low-dose Colchicine (COL) on ferroptosis-driven EMT in IPF, with a focus on the Snail family transcriptional repressor 1 (Snail1)-adipose triglyceride lipase (ATGL) axis as a novel pathway regulating redox balance and ferroptosis susceptibility.

Public transcriptomic and single-cell RNA sequencing datasets were analyzed to evaluate key gene expression patterns in IPF lung tissues and alveolar epithelial cells, with validation in a bleomycin (BLM)-induced pulmonary fibrosis mouse model. In parallel, transforming growth factor-β (TGF-β)-stimulated lung epithelial cell models were established to investigate ferroptosis- and EMT-related processes using genetic and pharmacological interventions. Chromatin immunoprecipitation and protein interaction assays were further performed to elucidate the underlying transcriptional regulatory mechanisms.

ATGL expression was consistently suppressed in alveolar epithelial cells from patients with IPF, as well as in BLM-injured mouse lungs and TGF-β-stimulated mouse lung epithelial (MLE-12) and human bronchial epithelial (BEAS-2B) cells. Complementary gain- and loss-of-function analyses, together with pharmacological inhibition of ATGL activity, demonstrated for the first time that ATGL mitigated ferroptosis-driven EMT in TGF-β-challenged MLE-12 cells by limiting intracellular iron accumulation and lipid peroxidation. Both Snail1 knockdown and low-dose COL upregulated ATGL, thereby inhibiting epithelial ferroptosis and subsequent EMT, whereas ATGL deficiency abrogated these protective effects. Snail1 directly repressed ATGL transcription by recruiting histone deacetylase 1 (HDAC1) and histone deacetylase 2 (HDAC2) to diminish histone acetylation at the Pnpla2 promoter. Pharmacologically, low-dose COL restored ATGL expression by suppressing the AKT-GSK3β-Snail1 signaling axis in MLE-12 cells and was accompanied by reduced Snail1 and increased ATGL expression in mouse lung tissue, ultimately alleviating ferroptosis-associated iron dysregulation, lipid peroxidation, and fibrotic remodeling in vivo.

These findings identify ATGL as an epithelial checkpoint that modulates ferroptosis susceptibility and EMT under fibrotic stress and reveal Snail1-dependent regulation of ferroptosis as a previously unappreciated noncanonical mechanism of EMT regulation. This study provides novel mechanistic insight into the actions of low-dose COL, supporting its translational relevance in IPF.