AGR2 is a target of canonical Wnt/β-catenin signaling and is important for stemness maintenance in colorectal cancer stem cells

Abstract

Colorectal cancer is one of the leading causes of cancer-related deaths. Due to relapse after current therapy regimens, cancer stem cells (CSCs) are being studied to target this small tumor-initiating population. Anterior gradient 2 (AGR2), a disulfide isomerase protein, is a well-known pro-oncogenic/metastatic oncogene overexpressed in various tumor tissues, including colon cancer. We found that AGR2 was a novel stem cell marker that was regulated by the canonical Wnt/β-catenin pathway in colon CSCs. AGR2 was highly co-expressed with surface stem cell markers in spheroidal culture. Silencing of AGR2 resulted in decreased sphere-forming ability and down-regulated expression of stem cell markers, whereas the opposite effects were seen with AGR2 overexpression. Moreover, patients with high β-catenin and AGR2 expression showed lower overall survival than those with low expression. In conclusion, our study describes a novel role for AGR2 as a stem cell marker that is highly regulated by canonical Wnt/β-catenin signaling in colorectal cancer.