Cholesterol-Depletion-Induced Membrane Repair Carries a Raft Conformer of P-Glycoprotein to the Cell Surface, Indicating Enhanced Cholesterol Trafficking in MDR Cells, Which Makes Them Resistant to Cholesterol Modifications

• Published in: International journal of molecular sciences 2023-08, Vol.24 (15), p.12335
• Main Authors: Gutay-Tóth, Zsuzsanna, Gellen, Gabriella, Doan, Minh, Eliason, James F, Vincze, János, Szente, Lajos, Fenyvesi, Ferenc, Goda, Katalin, Vecsernyés, Miklós, Szabó, Gábor, Bacso, Zsolt
• Format: Article
• Language: English
• Subjects: Antibodies; Cancer; Cells; Cholesterol; Cyclodextrins; Drug resistance in microorganisms; Genotype & phenotype; Glycoproteins; Lipids; Membranes; Monoclonal antibodies; Proteins
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms241512335

The human P-glycoprotein (P-gp), a transporter responsible for multidrug resistance, is present in the plasma membrane's raft and non-raft domains. One specific conformation of P-gp that binds to the monoclonal antibody UIC2 is primarily associated with raft domains and displays heightened internalization in cells overexpressing P-gp, such as in NIH-3T3 MDR1 cells. Our primary objective was to investigate whether the trafficking of this particular P-gp conformer is dependent on cholesterol levels. Surprisingly, depleting cholesterol using cyclodextrin resulted in an unexpected increase in the proportion of raft-associated P-gp within the cell membrane, as determined by UIC2-reactive P-gp. This increase appears to be a compensatory response to cholesterol loss from the plasma membrane, whereby cholesterol-rich raft micro-domains are delivered to the cell surface through an augmented exocytosis process. Furthermore, this exocytotic event is found to be part of a complex trafficking mechanism involving lysosomal exocytosis, which contributes to membrane repair after cholesterol reduction induced by cyclodextrin treatment. Notably, cells overexpressing P-gp demonstrated higher total cellular cholesterol levels, an increased abundance of stable lysosomes, and more effective membrane repair following cholesterol modifications. These modifications encompassed exocytotic events that involved the transport of P-gp-carrying rafts. Importantly, the enhanced membrane repair capability resulted in a durable phenotype for MDR1 expressing cells, as evidenced by significantly improved viabilities of multidrug-resistant Pgp-overexpressing immortal NIH-3T3 MDR1 and MDCK-MDR1 cells compared to their parents when subjected to cholesterol alterations.