ZNF326 promotes colorectal cancer epithelial-mesenchymal transition

Zinc-finger protein 326 (ZNF326) activity has been reported in different tumors, but its expression and possible mechanism of action in colorectal cancer are not known. In this study, we applied immunohistochemistry to detect the expression of ZNF326 in colorectal tissues. Next, we used a ZNF326 expression plasmid and small interfering (si) RNA-ZNF326 (siZNF326) to transfect colorectal cancer cell lines in order to determine the effect of ZNF326 on cell migration and as well as its potential role in promoting epithelial-mesenchymal transition (EMT). A higher ZNF326 expression in the nuclei of colorectal tumor cells compared to normal mucosa was observed (70.3%, 109/155 specimens vs. 23.2%, 36/155 specimens). A high ZNF326 expression level was positively correlated with tumor differentiation, tumor-node-metastasis (TNM) staging, and lymph node metastasis. Transfection of cancer cell lines (SW480 and SW620) with a ZNF326-overexpression vector promoted colorectal cancer cell invasion and altered the expression of EMT-related proteins. Vimentin, N-cadherin, Snail, and Slug were upregulated, whereas E-cadherin and zonula occludens-1 (ZO-1) were downregulated. In contrast, downregulation of ZNF326 expression using siRNA-ZNF326 in cancer cell lines (CL187 and RKO) resulted in the opposite findings. ZNF326 overexpression also upregulated the expression of latent transforming growth factor beta binding protein 4 (LTBP4) and p-Smad2/3. In conclusion, ZNF326 promoted the EMT and invasiveness of colorectal cancer cells. These findings are likely due to LTBP4 and p-Smad2/3 upregulation and, in turn, transforming growth factor beta (TGF-beta) signaling activation.