YAP Promotes Cell Proliferation and Epithelium-Derived Cytokine Expression via NF-κB Pathway in Nasal Polyps

BACKGROUND: Hippo-Yes-associated protein (YAP) pathway plays an important role in epithelial cell proliferation and inflammation development in chronic rhinosinusitis with nasal polyps (CRSwNP). However, the underlying mechanisms remain unclear. OBJECTIVE: This study intends to investigate the role of YAP and the nuclear factor kappa-B (NF-κB) pathway in cell proliferation and the expression of epithelium-derived cytokines in nasal polyps (NP). METHODS: The expression levels of YAP, TEA domain family member 1 (TEAD1), Ki-67, and NF-κB as well as interleukin (IL-) 33, IL-25 and thymic stromal lymphopoietin (TSLP) in sinonasal mucosa, primary nasal epithelial cells (NPECs), and human nasal epithelial RPMI 2650 cells were detected. NPECs were cultured and treated with verteporfin (VP), YAP shRNA or BAY 11–7082. RESULTS: The hippo pathway effector YAP, Ki-67, p65 NF-κB, and cyclin D1 were significantly increased in NP compared with control mucosa, which was accompanied by overexpression of IL-33, IL-25, and TSLP. Pharmaceutical inhibition of YAP by VP suppressed cell proliferation of RPMI 2650 cells by blocking cell cycle progression at G0/G1 without inducing obvious cell apoptosis. Furthermore, lentiviral transfection-mediated knockdown of hippo pathway activity reduced the expression of IL-33, IL-25, TSLP as well as p65 NF-κB in RPMI 2650 cells. Downregulation of NF-κB pathway with BAY 11–7082 in NPECs could decrease the mRNA level of TSLP, IL-33 and IL-25 accordingly. CONCLUSION: Inhibition of hippo pathway suppressed nasal epithelial cell proliferation and declined the expression of epithelium-derived cytokines via the NF-κB pathway in NPECs.