Evaluation of ST6Gal1 expression and clinicopathological significance in human glioma

Glioma is the most common brain tumor, accounting for a large majority of cancer-related deaths. β-galactoside α2, 6 sialyltranferase 1 (ST6Gal1), the primary enzyme responsible for the conjugation of α2, 6 sialic acids to protein and lipid targets, is strongly associated with the occurrence and development of several brain tumor types. Still, the expression, targets, and functions of ST6Gal1 in glioma patients remain undetermined. As sialylation of the Ig-like cell adhesion family molecules have prominent roles in the latter's regulation in other biological contexts, we screened for members that have potential to be regulated by ST6Gal1 in silico and examined co-expressed protein modules using data derived from the Cancer Genome Atlas (TCGA) database, and we identified neural cell adhesion molecule (NCAM1) as a major ST6Gal1-interacting target. Bioinformatic binding analysis confirmed the interaction of ST6Gal1 and NCAM1. Immunohistochemistry was then used to evaluate post-operative samples from 156 patients with gliomas. ST6Gal1 and NCAM1 were co-expressed in gliomas, and their expression correlated significantly (p = 0.002) by univariate analysis. Our study also found that the expression levels of both ST6Gal1 and NCAM1 corresponded negatively with glioma grade, isocitrate dehydrogenase (IDH) mutation, and proliferation index (Ki67). Consistently, Kaplan-Meier survival curves showed that lower ST6Gal1 and NCAM1 protein levels are linked to unfavorable outcomes in glioma patients (p = 0.018 and p < 0.001, respectively). Our data indicate that ST6Gal1 may participate in the inhibition of oncogenesis and malignant progression via interacting with and targeting NCAM1 in glioma, thus presenting a novel strategy for intervention.