Hypoxia and Oxidation Pathway Crosstalk in Head and Neck Squamous Cell Carcinoma.

Abstract

Treatment resistance remains a significant challenge in head and neck squamous cell carcinoma (HNSCC). Alterations in oxidative stress and hypoxia pathways predict poor therapeutic outcomes. The nuclear factor erythroid 2-related factor 2 pathway is the key regulator of oxidative stress response and an established mediator of treatment resistance. There is emerging evidence suggesting that its activation may influence hypoxia-inducible factor 1α (HIF-1α) signaling. However, this relationship remains poorly defined in HNSCC. Translational research. University-based research laboratory. This study utilized bioinformatic and experimental approaches to investigate the relationship between NRF2 and HIF-1α expression. Correlations among KEAP1, NFE2L2 (NRF2), and HIF1A (HIF-1α) mRNA were examined using The Cancer Genome Atlas (TCGA) and RNA-sequencing data from patient-derived HNSCC cell lines. Functional validation was performed using siRNA-mediated KEAP1 knockdown in vitro, followed by quantitative polymerase chain reaction (PCR) and Western blot analysis. TCGA analysis revealed that HIF1A mRNA positively correlated with NFE2L2 (NRF2), though the expression did not differ between NRF2 pathway-mutant and wild-type tumors. No significant correlation between HIF1A and NFE2L2 or KEAP1 mRNA was observed in HNSCC cell lines. KEAP1 knockdown achieved >90% transcript reduction and significantly increased the expression of the NRF2 target gene NQO1. Although NFE2L2 and HIF1A transcripts were unchanged, Western blot analysis demonstrated increased NRF2 and HIF-1α protein levels, suggesting a post-translational relationship. KEAP1 knockdown promotes NRF2 upregulation and HIF-1α protein accumulation in HNSCC independent of mRNA changes, suggesting protein-level or redox-mediated crosstalk between oxidative stress and hypoxia pathways.