O-glycan truncation enhances cancer-related functions of CD44 in gastric cancer.

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.