Regulation of tumor progression via the Snail‐RKIP signaling pathway by nicotine exposure in head and neck squamous cell carcinoma

Recent studies suggest that long-term exposure of the carcinogen 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) found in tobacco smoke is involved in the progression of head and neck squamous cell carcinoma (HNSCC). The underlying nicotine-mediated mechanism remains unclear.An analysis of SCC-25 and Fadu cells with or without NNK exposure focusing on the evaluation of migration and invasion abilities, the expression of epithelial-mesenchymal transition, drug-resistance-related genes, properties of cancer stem cells (CSCs), and anti-apoptosis was performed.Long-term NNK exposure enhances migration and invasion with morphological alterations in a dose-dependently manner. Furthermore, NNK exposure also upregulates Snail, promotes sphere-forming ability, and overexpresses aldehyde dehydrogenase 1 (ALDH1), Nanog, OCT4, ABCG2, and MDR1.The current study confirmed that long-term NNK exposure plays a role in HNSCC by increasing anti-apoptosis and therapeutic resistance via the Snail-RKIP signaling pathway. Our data also suggest that α7 nicotinic acetylcholine receptor (α7-nAChR) inhibition or targeting Snail may provide a feasible rationale for preventing the progression of HNSCC.