• Key enzyme for the biosynthesis of b-series gangliosides on glycolipids, thus called GD3 synthase. ST8Sia-I uses GM3 (Neu5Acα2-3Galβ1-4Glcβ1-O-Cer) to form GD3 (Neu5Acα2-8Neu5Acα2-3Galβ1-4Glcβ1-O-Cer) (b-series). This can then form GT3 (c-series gangliosides). ST8Sia I and b- and c-series gangliosides are implicated in oncogenesis by mediating cell proliferation, migration, tumor growth, and angiogenesis. GD3 is weakly expressed in most normal cells but upregulated in cancer.
• Expressed in various organs, particularly the brain, and overexpressed in neuroectoderm-derived malignant cells such as melanoma, glioblastoma, neuroblastoma, and estrogen receptor-negative breast cancer.
• ST8SIA1 knockout mice completely lack b- and c-series gangliosides. However, they show almost complete nervous tissue morphology and no apparent abnormal behavior. But they show reduced reneration of nerve, suggesting a role for the enzyme in repair rather than normal differentiation.
• ST8SIA1 displayed higher expression among ER-negative breast cancer tumors and this is assocaiated with poor pathohistological grading.