T-Synthase Deficiency Enhances Oncogenic Features in Human Colorectal Cancer Cells via Activation of Epithelial-Mesenchymal Transition

Abstract EN

Background.

Immature truncated O-glycans such as Tn antigen are frequently detected in human colorectal cancer (CRC); however, the precise pathological consequences of Tn antigen expression on CRC are unknown.

T-synthase is the key enzyme required for biosynthesis of mature O-glycans.

Here we investigated the functional roles of Tn antigen expression mediated by T-synthase deficiency in CRC cells.

Methods.

To knock out T-synthase, we used CRISPR-Cas9 technology to target C1GALT1, the gene encoding T-synthase, in a CRC cell line (HCT116).

Deletion of T-synthase was confirmed by western blotting, and expression of Tn antigen was determined by flow cytometry in HCT116 cells.

We then assessed the biological effects of T-synthase deficiency on oncogenic behaviors in HCT116 cells.

Furthermore, we analyzed the mechanistic role of T-synthase deficiency in cancer cells by determining the epithelial-mesenchymal transition (EMT) pathway.

Results.

We showed that forced knockout of T-synthase in HCT116 cells significantly induced Tn antigen expression, which represented the occurrence of aberrant O-glycosylation.

Loss of T-synthase significantly enhanced cell proliferation and adhesion, as well as migration and invasiveness in culture.

More importantly, we demonstrated that T-synthase deficiency directly induced classical EMT characteristics in cancer cells.

E-cadherin, a typical epithelial cell marker, was markedly decreased in T-synthase knockout HCT 116 cells, accompanied by an enhanced expression of mesenchymal markers including snail and fibronectin (FN).

Conclusions.

These findings indicate that T-synthase deficiency in CRC cells not only is responsible for aberrant O-glycosylation, but also triggers the molecular process of EMT pathway, which may translate to increased invasiveness and metastasis in cancers.