ST8SIA3 is a sialyltransferase that catalyzes the transfer of sialic acid onto terminal sialic acid residues of glycoproteins and glycolipids, forming oligosialic and polysialic acid structures 123. The enzyme preferentially modifies N-linked oligosaccharides of glycoproteins, including FETUB and AHSG, as well as alpha-2,3-sialylated glycosphingolipids such as ganglioside GM3 13. In the striatum, ST8SIA3 mediates formation of disialylated and trisialylated glycotopes that regulate protein distribution in lipid rafts and modulate striatal function. Disease relevance is substantial: ST8SIA3 expression is elevated in glioblastoma cancer stem cells, where it synthesizes the A2B5 epitope recognized by A2B5 antibodies, promoting proliferation, migration, clonogenicity, and tumorigenesis 45. ST8SIA3 is also aberrantly methylated and dysregulated in melanoma, hepatocellular carcinoma, breast and cervical cancers 6, as well as endometrial cancer where it functions as a hub gene in lncRNA-miRNA-mRNA regulatory networks 7. Additionally, ST8SIA3 participates in cardiac reprogramming and spinal cord injury recovery processes 89. Clinically, ST8SIA3 represents a promising therapeutic target in glioblastoma and an emerging biomarker for multiple malignancies.