Abstract: P-glycoprotein (P-gp), also known as ABCB1, is a member of the ABC transporter family of proteins. P-gp is an ATP-dependent drug efflux pump that is localized to the plasma membrane of mammalian cells and confers multidrug resistance in neoplastic cells. P-gp is a 140-kDa polypeptide that is glycosylated to a final molecular weight of 170 kDa. Our experimental model used two variants of L1210 cells in which overexpression of P-gp was achieved: either by adaptation of parental cells (S) to vincristine (R) or by transfection with the human gene encoding P-gp (T). R and T cells were found to differ from S cells in transglycosylation reactions in our recent studies. The effects of tunicamycin on glycosylation, drug efflux activity and cellular localization of P-gp in R and T cells were examined in the present study. Treatment with tunicamycin caused less concentration-dependent cellular damage to R and T cells compared with S cells. Tunicamycin inhibited P-gp N-glycosylation in both of the P-gp-positive cells. However, tunicamycin treatment did not alter either the P-gp cellular localization to the plasma membrane or the P-gp transport activity. The present paper brings evidence that independently on the mode of P-gp expression (selection with drugs or transfection with a gene encoding P-gp) in L1210 cells, tunicamycin induces inhibition of N-glycosylation of this protein, without altering its function as plasma membrane drug efflux pump.
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Šereš, M.; Cholujová, D.; Bubenčíkova, T.; Breier, A.; Sulová, Z. Tunicamycin Depresses P-Glycoprotein Glycosylation Without an Effect on Its Membrane Localization and Drug Efflux Activity in L1210 Cells. Int. J. Mol. Sci. 2011, 12, 7772-7784.
Šereš M, Cholujová D, Bubenčíkova T, Breier A, Sulová Z. Tunicamycin Depresses P-Glycoprotein Glycosylation Without an Effect on Its Membrane Localization and Drug Efflux Activity in L1210 Cells. International Journal of Molecular Sciences. 2011; 12(11):7772-7784.
Šereš, Mário; Cholujová, Dana; Bubenčíkova, Tatiana; Breier, Albert; Sulová, Zdenka. 2011. "Tunicamycin Depresses P-Glycoprotein Glycosylation Without an Effect on Its Membrane Localization and Drug Efflux Activity in L1210 Cells." Int. J. Mol. Sci. 12, no. 11: 7772-7784.