CD44 isoforms are often upregulated in gastric cancer and have been associated with increased metastatic potential and poor survival. To evaluate the functional impact of O-glycan truncation on CD44 we have analysed glyco-engineered cancer cell models displaying shortened O-glycans. Here, we demonstrate that induction of aberrant O-glycan termination through various molecular mechanisms affects CD44 molecular features. We show that CD44 is a major carrier of truncated O-glycans and that this truncation is accompanied by an increased hyaluronan binding capacity and affects extracellular shedding. In addition, short O-glycans promoted the colocalization of CD44v6 with the receptor tyrosine kinase RON and concomitantly increased activation. Our in vitro findings were validated in gastric cancer clinical samples.
Keywords: CD44; gastric cancer; glycosylation; hyaluronic acid; proximity ligation assay; sialylation.
© 2019 Federation of European Biochemical Societies.