Identification of odontogenic ameloblast associated as a novel target gene of the Wnt/ß-catenin signaling pathway.

The Wnt/ß-catenin signaling pathway plays a key role in development and carcinogenesis. Although some target genes of this signaling have been identified in various tissues and neoplasms, the comprehensive understanding of the target genes and their roles in the development of human cancer, including hepatoma and colorectal cancer remain to be fully elucidated. In this study, we searched for genes regulated by the Wnt signaling in liver cancer using HuH-7 hepatoma cells. A comparison of the expression profiles between cells expressing an active form of mutant ß-catenin and cells expressing enhanced green fluorescent protein (EGFP) identified seven genes upregulated by the mutant ß-catenin gene (CTNNB1). Among the seven genes, we focused in this study on ODAM, odontogenic, ameloblast associated, as a novel target gene. Interestingly, its expression was frequently upregulated in hepatocellular carcinoma, colorectal adenocarcinoma, and hepatoblastoma. We additionally identified a distant enhancer region that was associated with the ß-catenin/TCF7L2 complex. Further analyses revealed that ODAM plays an important role in the regulation of the cell cycle, DNA synthesis, and cell proliferation. These data may be useful for clarification of the main molecular mechanism(s) underlying these cancers.

Motile sperm domain containing 1 is upregulated by the Wnt/ß-catenin signaling pathway in colorectal cancer.

Aberrant activation of the Wnt/ß-catenin signaling pathway plays a crucial role in the development and progression of colorectal cancer. Previously, we identified a set of candidate genes that were regulated by this signaling pathway, and the present study focused on motile sperm domain containing 1 (MOSPD1). Immunohistochemical staining revealed that the expression of MOSPD1 was elevated in tumor cells from colorectal cancer tissues compared with in non-tumor cells. Using ChIP-seq data and the JASPAR database, the regulatory region(s) in the MOSPD1 gene as a target of the Wnt/ß-catenin signaling pathway were searched, and a region containing three putative TCF-binding motifs in the 3'-flanking region was identified. Additional analyses using reporter assay and ChIP-quantitative PCR suggested that this region harbors enhancer activity through an interaction with transcription factor 7 like 2 (TCF7L2) and ß-catenin. In addition, chromatin conformation capture assay revealed that the 3'-flanking region interacts with the MOSPD1 promoter. These data suggested that MOSPD1 was regulated by the ß-catenin/TCF7L2 complex through the enhancer element located in the 3'-flanking region. These findings may be helpful for future studies regarding the precise regulatory mechanisms of MOSPD1.