Down-regulation of Wnt-4 and up-regulation of Wnt-5a expression by epithelial-mesenchymal transition in human squamous carcinoma cells

Abstract

Gene expression of Wnt-1, 2, 3, 4, 5a, 6 and 7a was analyzed by RTPCR in eleven squamous cell carcinoma (SCC) cell lines and compared with that in two normal oral keratinocyte strains. There appeared to be an inverse relationship between Wnt-4 and Wnt-5a expressions, i.e., Wnt-4 was not expressed in HOC719-NE, HOC313 or TSU cells, while Wnt-5a was strongly expressed only in these cells. These cell lines showed decreased expression of E-cadherin and elevated expression of vimentin accompanied with strong expressions of Snail and δEF1, which have been reported to be transrepressors of E-cadherin and to trigger epithelial-mesenchymal transition (EMT), suggesting associations of Wnt-4 with epithelial phenotype and Wnt-5a with mesenchymal phenotype of SCC cells. To study whether the expressions of these Wnt genes are regulated by EMT, we transfected a Snail-expression vector into A431 and OM-1 cells, which express Wnt-4 but not Wnt-5a. The stably Snail-overexpressing clones showed spindle morphology, increased expression of vimentin and decreased expression of E-cadherin accompanied with augmented expression of δEF1. In these clones, down-regulation of Wnt-4 and up-regulation of Wnt-5a were clearly observed. These results indicated that Wnt-4 and Wnt-5a are oppositely affected by EMT, and down-regulation of Wnt-4 and up-regulation of Wnt-5a are possible markers of the malignant phenotype of human SCC.