Identification of Glycan Structure Alterations on Cell Membrane Proteins in Desoxyepothilone B Resistant Leukemia Cells
Packer, Nicolle H.
Resistance to tubulin-binding agents used in cancer is often multifactorial and can include changes in drug accumulation and modified expression of tubulin isotypes. Glycans on cell membrane proteins play important roles in many cellular processes such as recognition and apoptosis, and this study investigated whether changes to the glycan structures on cell membrane proteins occur when cells become resistant to drugs. Specifically, we investigated the alteration of glycan structures on the cell membrane proteins of human T-cell acute lymphoblastic leukemia (CEM) cells that were selected for resistance to desoxyepothilone B (CEM/dEpoB). The glycan profile of the cell membrane glycoproteins was obtained by sequential release of N- and O-glycans from cell membrane fraction dotted onto polyvinylidene difluoride membrane with PNGase F and β-elimination respectively. The released glycan alditols were analyzed by liquid chromatography (graphitized carbon)-electrospray ionization tandem MS. The major N-glycan on CEM cell was the core fucosylated α2–6 monosialo-biantennary structure. Resistant CEM/dEpoB cells had a significant decrease of α2–6 linked sialic acid on N-glycans. The lower α2–6 sialylation was caused by a decrease in activity of β-galactoside α2–6 sialyltransferase (ST6Gal), and decreased expression of the mRNA. It is clear that the membrane glycosylation of leukemia cells changes during acquired resistance to dEpoB drugs and that this change occurs globally on all cell membrane glycoproteins. This is the first identification of a specific glycan modification on the surface of drug resistant cells and the mechanism of this downstream effect on microtubule targeting drugs may offer a route to new interventions to overcome drug resistance.
This research was supported by a Cancer Institute of New South Wales Infrastructure Award, Children’s Cancer Institute Australia for Medical Research, which is affiliated with the University of New South Wales and the Sydney Children’s Hospital and grants from the New South Wales Cancer Council and a National Health and Medical Research Council Senior Fellowship (M. Kavallaris).
Molecular & Cellular Proteomics
The American Society for Biochemistry and Molecular Biology, Inc.
This research was originally published in Molecular & Cellular Proteomics. Miyako Nakano, Rohit Saldanha, Anja Göbel, Maria Kavallaris, Nicolle H. Packer. Identification of Glycan Structure Alterations on Cell Membrane Proteins in Desoxyepothilone B Resistant Leukemia Cells. Mol Cell Proteomics. 2011; 10(11):M111.009001. © the American Society for Biochemistry and Molecular Biology.