Waterpipe Smoke Condensate Impairs p53 Nuclear Localization in Association with HIF-1α Stabilization

Waterpipe (shisha or hookah) smoking is recognized as a risk factor for lung cancer; however, its interference with hypoxia stress and tumor suppressor pathways in non-small cell lung cancer (NSCLC) is poorly defined. In this study, NSCLC cell lines (A549, H460, H226 with endogenous wild-type p53, and H1299 transiently expressing wild-type or p53 mutants) were exposed to waterpipe smoke condensate (WPSC) under normoxic and/or hypoxic conditions. WPSC induced HIF-1α stabilization under normoxic conditions, accompanied by predominantly cytoplasmic localization and without corresponding induction of the canonical HIF-1 target genes examined. In parallel, WPSC transiently reduced nuclear p53 localization without altering total p53 protein levels. In A549 cells, WPSC pretreatment attenuated irradiation-induced expression of the p53 target genes cyclin-dependent kinase inhibitor 1A (CDKN1A) and BTG anti-proliferation factor 2 (BTG2). Pharmacological inhibition of HIF-1α partially restored nuclear p53 localization, supporting the involvement of HIF-1α in this response. Co-immunoprecipitation demonstrated an association between HIF-1α and p53 following WPSC exposure. Collectively, these findings show that WPSC-induced HIF-1α stabilization under normoxic conditions is associated with transient alterations in p53 localization and transcriptional response, supporting an involvement of HIF-1α in this process.