Upregulation of WDR4 mediated by RBFOX2 promotes laryngeal cancer progression through the WDR4/m7G/lncRNA ZFAS1/RBFOX2 axis

Abstract

High levels of the N7 methylguanosine (m7G) methyltransferase WD repeat domain 4 (WDR4) are associated with the progression of multiple tumors, including head and neck squamous cell carcinoma. Laryngeal cancer (LC) is the second most common malignant tumor of the head and neck. However, the role of WDR4 in LC remains unclear. Here, we found that WDR4 expression was significantly upregulated in LC tissues and cells. Silencing WDR4 inhibited proliferation, invasion, and epithelial-mesenchymal transition (EMT, manifested by an increase in E-cadherin protein levels and a decrease in N-cadherin and Vimentin protein levels) in TU177 and M4E cells. Furthermore, the levels of m7G and ZFAS1 were significantly upregulated in LC tissues and cells. Mechanistic studies revealed that WDR4 upregulated the levels of ZFAS1 and RBFOX2 proteins by promoting the stability of ZFAS1 in an m7G-dependent manner, and RBFOX2 promoted WDR4 expression by binding to WDR4 mRNA. Overexpression of WDR4 increased m7G and ZFAS1 levels, whereas overexpression of WDR4 with m7G catalytic site mutation had no effect on m7G and ZFAS1 levels in TU177 and M4E cells. Silencing ZFAS1 or RBFOX2 counteracted the promoting effect of WDR4 overexpression on the malignant proliferation of TU177 and M4E cells. TU177 cells transfected with sh-WDR4 lentiviral vectors were intraperitoneally injected into nude mice to construct xenograft tumor models. Knockdown of WDR4 significantly inhibited LC tumor growth in vivo. In conclusion, RBFOX2-mediated upregulation of WDR4 promoted LC progression through the WDR4/m7G/ZFAS1/RBFOX2 axis.

Keywords: Laryngeal cancer; LncRNA ZFAS1; M7G; RBFOX2; WDR4.