Characterization of C170RF45 as a novel target of the Wnt/β-catenin pathway

Abstract

β-catenin is a key component of Wnt pathway which plays an important role in tumorigenesis. In our previous study, candidate genes regulated byWnt/ β-catenin/TCF pathway were identified in hepatocellular carcinoma-derived Huh7 cells overexpressing hyperactive β-catenin (S33Y mutant). SAGE (Serial Analysis of Gene Expression) and genome wide microarray analysis were performed to compare global gene expression between Huh7 cells with high and low TCF activity. After comparison, C17orf45 was found to be up-regulated in Huh7 cells with high β-catenin/TCF activity. In this study, C17orf45 gene was further verified as a Wnt target based on lithium treatment, GFP/luciferase reporter, and ChIP assays. C17orf45 is a novel gene that has not been studied before and its expression is up-regulated in several brain tumors according to sagereveal (a bioinformatic tool data mining gene expression data from tumor and normal samples using SAGE library data). Based on this prediction, to investigate the potential link between C17orf45 and tumorigenesis; expression analysis was performed in human brain tumors and the growth effect on U373-MG cells was examined with proliferation assay. To investigate the subcellular localization of C17orf45 protein, GFP fused constructs were used and the localization was found to be mitochondria. Identification of novel targets of Wnt signaling is important for better understanding of cancer pathophysiology and may serve as potential targets for drug therapies. New targets of this pathway will expand the cancer research area. To sum up, results of this study reveal a novel gene putatively implicated in tumorigenesis and the Wnt pathway.