Abstract
Arsenic exposure increases lung cancer risk, yet its molecular mechanisms remain unclear but are linked to peroxisome proliferator-activated receptor gamma (PPARγ). We investigated PPARγ-related molecules affected by sodium arsenite (NaAR) in non-small cell lung cancer (NSCLC) cells using immunochemical, gene knockdown, and immunoprecipitation approaches. PPARγ was critical for NSCLC growth, as high PPARγ-expressing A549 cells proliferated more than low-expressing H1299 cells after NaAR treatment. In A549 cells, NaAR upregulated polyubiquitinated PPARγ, activating cell cycle arrest and DNA damage response pathways. Rather than inducing significant caspase-dependent apoptosis, NaAR activated nuclear factor-kappa B and downregulated mixed lineage kinase domain-like (MLKL) via K63-linked polyubiquitinated receptor-interacting protein kinase 1, thereby inhibiting apoptosis and necroptosis. PPARγ knockdown or NAD(+) supplementation induced PARP-1 hyperactivation and MLKL upregulation, leading to DNA damage and necroptosis. PARP-1 inhibition by 3-aminobenzamide induced apoptosis, indicating that PPARγ regulates apoptosis and necroptosis through PARP-1 activation. Proteasome inhibition increased polyubiquitinated PPARγ but not p53. Leptomycin B induced PPARγ degradation and p53 accumulation, promoting necroptosis and apoptosis, suggesting cytoplasmic p53 contributes to cell death. p62 interacted with PPARγ and p53, and its knockdown suppressed their NaAR-induced upregulation. In conclusion, NaAR-induced PPARγ promotes A549 cell survival by enhancing DNA repair and inhibiting apoptosis and necroptosis via cooperation with p53 and p62, highlighting PPARγ as a potential therapeutic target.