The functional DIAPH3-FOXM1 interaction modulates the aggressive transformation of anaplastic thyroid carcinoma cells and Wnt/β-catenin signalling.

Abstract

Anaplastic thyroid carcinoma (ATC) is reckoned as an infrequent but extremely advanced neoplasm of the endocrine system. Diaphanous-related formin 3 (DIAPH3) has been extensively implicated in carcinogenic events, but it has not been introduced in ATC. Herein, the role of DAPIH3 and the interrelated functional mechanism are characterised in ATC. The Gene Expression Omnibus (GEO) database was checked for differential DIAPH3 expression in ATC samples and noncancerous samples. Western blotting examined DIAPH3 and forkhead box M1 (FOXM1) expression in ATC cells. In vitro cell counting kit 8 (CCK-8) method, 5-ethynyl-2'-deoxyuridine (EdU) incorporation, Scratch, Matrigel invasion, and terminal-deoxynucleotidyl transferase mediated nick end labelling (TUNEL) assays were used to assess the potential of cells to proliferate, migrate, and invade as well as the cellular apoptotic rate. Co-IP was applied to access DIAPH3-FOXM1 protein interaction. Western blotting also disclosed the expression of proteins associated with apoptosis and Wnt/β-catenin signalling. DIAPH3 was hyper-expressed in papillary cell carcinoma (PTC) tissues and cells. Depleting DIAPH3 strongly eliminated the proliferative, migratory, as well as invasive capabilities of PTC cells while intensifying the apoptotic ability. FOXM1 also harboured elevated expression in PTC cells. FOXM1 was the binding partner with DIAPH3, and the 2 were positively correlated. FOXM1 upregulation again exacerbated the potentials to proliferate, migrate, and invade but it repressed the apoptotic rate of DIAPH3-depleted cells. Furthermore, loss of DIAPH3 downregulated FOXM1 to block Wnt/b-catenin signalling in PTC cells. Combined with these findings, DIAPH3 might favour the aggressive advancement of ATC and motivate the Wnt/β-catenin signalling via binding with FOXM1.