ZIC5, a survival biomarker, facilitates tumor progression and stemness in colon cancer via the activation of the Wnt signaling pathway

Colorectal cancer (CRC), a highly heterogeneous disease, is the second leading cause of cancer related deaths. Mounting evidence has indicated that the zinc finger of the cerebellum 5 (ZIC5) is involved in the pathological processes of cancer. At present, there are few and conflicting studies on ZIC5 in CRC. The aim of this study was to elucidate the clinical value, function and molecular mechanism of ZIC5 in colon cancer. ZIC5 expression analysis in pan-cancer was performed using the TCGA database. The correlation of ZIC5 expression with clinicopathologic parameters of colon cancer was assessed in public and external datasets, respectively. The influence of ZIC5 expression on survival was analyzed by Kaplan-Meier (KM) curve and Cox regression models. In addition, a series of in vitro experiments on cell proliferation, invasion, migration and stemness were performed to further explore the function and potential mechanisms of ZIC5 in colon cancer. ZIC5 mRNA expression is significantly elevated in the vast majority of cancers. We found that ZIC5 is elevated in colon cancer tissues, and high ZIC5 expression was associated with poorer survival of colon cancer patients. ZIC5 expression was positively correlated with the malignant pathological phenotype, and it's an independent risk marker for the overall survival (OS) of colon cancer patients. We demonstrated that ZIC5 promoted proliferation, invasion, migration and EMT of colon cancer cells. Additionally, ZIC5 enhances colon cancer stem cell (CSC) properties. Mechanistically, ZIC5 functions in colon cancer cells by upregulating Wnt signaling. ZIC5 could enhance Wnt/β-catenin signaling by interacting with β-catenin. Interestingly, in HCT116 cells, ZIC5 doesn't affect the protein level of β-catenin and its nuclear translocation likely due to the deletion mutation of β-catenin at Ser45. We identified ZIC5 as a survival marker for colon cancer patients. Our study shows that inhibition of ZIC5 might be a potential therapeutic strategy for colon cancer.