O -GlcNAcylation: an important post-translational modification and a potential therapeutic target for cancer therapy

O -linked β- d - N -acetylglucosamine ( O -GlcNAc) is an important post-translational modification of serine or threonine residues on thousands of proteins in the nucleus and cytoplasm of all animals and plants. In eukaryotes, only two conserved enzymes are involved in this process. O -GlcNAc transferase is responsible for adding O -GlcNAc to proteins, while O -GlcNAcase is responsible for removing it. Aberrant O -GlcNAcylation is associated with a variety of human diseases, such as diabetes, cancer, neurodegenerative diseases, and cardiovascular diseases. Numerous studies have confirmed that O -GlcNAcylation is involved in the occurrence and progression of cancers in multiple systems throughout the body. It is also involved in regulating multiple cancer hallmarks, such as metabolic reprogramming, proliferation, invasion, metastasis, and angiogenesis. In this review, we first describe the process of O -GlcNAcylation and the structure and function of O -GlcNAc cycling enzymes. In addition, we detail the occurrence of O -GlcNAc in various cancers and the role it plays. Finally, we discuss the potential of O -GlcNAc as a promising biomarker and novel therapeutic target for cancer diagnosis, treatment, and prognosis.