Abstract
P-glycoprotein (P-gp) overexpression is the most frequently observed cause of multidrug resistance in neoplastic cells. In our experiments, P-gp was expressed in L1210 mice leukemia cells (S cells) by selection with vincristine (R cells) or transfection with the gene encoding human P-gp (T cells). Remodeling of cell surface sugars is associated with P-gp expression in L1210 cells as a secondary cellular response. In this study, we monitored the alteration of cell surface saccharides by Sambucus nigra agglutinin (SNA), wheat germ agglutinin (WGA) and Maackia amurensis agglutinin (MAA). Sialic acid is predominantly linked to the surface of S, R and T cells via α-2,6 branched sugars that tightly bind SNA. The presence of sialic acid linked to the cell surface via α-2,3 branched sugars was negligible, and the binding of MAA (recognizing this branch) was much less pronounced than SNA. WGA induced greater cell death than SNA, which was bound to the cell surface and agglutinated all three L1210 cell-variants more effectively than WGA. Thus, the ability of lectins to induce cell death did not correlate with their binding efficiency and agglutination potency. Compared to S cells, P-gp positive R and T cells contain a higher amount of N-acetyl-glucosamine on their cell surface, which is associated with improved WGA binding. Both P-gp positive variants of L1210 cells are strongly resistant to vincristine as P-gp prototypical drug. This resistance could not be altered by liberalization of terminal sialyl residues from the cell surface by sialidase.
Highlights
Multidrug resistance (MDR) of neoplastic cells represents an obstacle in the effective treatment of cancer with chemotherapy [1]
Change in composition of cell surface sugars detected by specific lectins in the present paper seems to be directly related to P-gp overexpression and is independent on way by which P-gp expression was achieved. This suggestion could be deduced from fact that R and T cells show similar interaction with all three of the lectins applied in this study, and this behavior differs in S cells
We measured cell agglutination, cell death effects induced by lectins and lectin binding to cell surfaces (Figures 2–4 and 6)
Summary
Multidrug resistance (MDR) of neoplastic cells represents an obstacle in the effective treatment of cancer with chemotherapy [1]. The alteration of cell surface sugars reduced ConA binding and elevated lectin (Lycopersicum esculentum agglutinin, LEA) binding to the cell surface of P-gp positive L1210 cells compared with their P-gp negative counterparts [20] Both of these lectins failed to bind to saccharide parts directly linked to P-gp, suggesting considerable changes in the glycoside parts of glycoproteins that are distinct from P-gp in P-gp positive L1210 cells. A similar depression of ConA binding was observed following P-gp overexpression by selection of L1210 cells with vincristine or by transfection of L1210 cells with the human gene encoding P-gp [21] Taken together, these data indicate that overexpression of P-gp in L1210 cells is directly associated with the physico-chemical alteration of the cell surface due to remodeling of the glycoside parts of several proteins in plasma membrane. These variants were obtained from parental cells (S) via stepwise adaptation to the vincristine (R) [23] or stable transfection with the human gene encoding P-gp (T) [21]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
