p63 – Key molecule in the early phase of epithelial abnormality in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common lung disease predisposing lung cancer. To clarify the early phase of epithelial abnormalities in IPF, we used an in vitro squamous metaplasia model, transforming growth factor β1 (TGF β1)-treated airway epithelial cells (BEAS-2B). The model repeated the expression of squamous epithelial character, such as involucrin, and keratin 6 and 14. DNA microarray analysis disclosed a unique expression signature in TGF β1-treated airway epithelial cells, 20 specifically up-regulated genes including p63, jagged 1 (jag1) and the genes of structure proteins. Western blotting and RT–PCR analysis revealed that ΔNp63α was the dominant isoform of p63 in our experimental model. Immunohistochemical analysis demonstrated the expression of p63 and jag1 in lung tissues of IPF. Inhibition of p63 with siRNA caused the down-regulation of jag1 expression, but not of involucrin, or keratin 6 and 14. Interestingly, the up-regulation of p63 was totally suppressed by N-acetyl-l-cysteine (NAC), but not by dexamethasone or pirfenidone. Thus, the p63–jag1 pathway may be up-regulated at an early phase of epithelial abnormalities in IPF, which can be overcome by NAC even in the TGF β1-rich milieu.