p38 MAPK mediates epithelial-mesenchymal transition by regulating p38IP and Snail in head and neck squamous cell carcinoma

In the present study, we investigated the role of p38-p38IP signaling in the inflammation-induced promotion of epithelial-to-mesenchymal transition (EMT) in Head and Neck Squamous Cell Carcinoma (HNSCC). Quantitative RT-PCR, western blot analysis, spheroid modeling and immunohistochemical staining of human HNSCC tissue sections were used. p38 inhibitor treated and p38 shRNA HNSCC cell lines demonstrate a significant upregulation in E-cadherin mRNA and a decrease in the mRNA expression of Snail. p38 binds to and stabilizes p38IP, a subunit of histone SPT3-TAF9-GCN5 acetyltransferase (STAGA), resulting in enhanced transcription of Snail. p38 shRNA HNSCC cell lines show a less invasive phenotype in a spheroid model. In clinical HNSCC samples, p38 interacting protein (p38IP) is significantly increased compared to adjacent normal tissue. An inverse relationship between p38, p38IP and E-cadherin is demonstrated. Herein we provide the first report that p38-p38IP is required for the Snail-induced E-cadherin down-regulation and cell invasion in HNSCC.