To identify the deficient enzyme(s) in the glycosylation pathway that yield incomplete maturation of (uPAR) protein

We previously demonstrated plasticity in urokinase receptor (u-PAR) display in clonal colon cancer cells (Cancer Research 66: 7957-7967 (2006)). Thus, u-PAR display oscillates 10 fold between high and low density at the cell surface. We have determined that this oscillation in u-PAR display is posttranslational in nature. Thus, while clonal cell populations with high and low u-PAR density synthesize u-PAR at the same rate, the protein is inefficiently glycosylated in cells down-shifted for u-PAR display and subsequently degraded. The objective of this study is to identify the deficient enzyme(s) in the glycosylation pathway that yield incomplete maturation of the u-PAR protein and hence its premature degradation. We will compare a clonal population of the RKO colon cancer cell line (designated RKO C2) with a population derived (by FACS sorting for low u-PAR) from RKO C2 (designated RKO C2 F3).