The Role of CD44 and ERM Proteins in Expression and Functionality of P-glycoprotein in Breast Cancer Cells.

Deep Pokharel,Steven Djordjevic,Ritu Jaiswal,Jamie Lu,Mary Bebawy,Matthew Padula

doi:10.3390/molecules21030290

Deep Pokharel, Steven Djordjevic + Show 4 more

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https://doi.org/10.3390/molecules21030290

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Abstract

Multidrug resistance (MDR) is often attributed to the over-expression of P-glycoprotein (P-gp), which prevents the accumulation of anticancer drugs within cells by virtue of its active drug efflux capacity. We have previously described the intercellular transfer of P-gp via extracellular vesicles (EVs) and proposed the involvement of a unique protein complex in regulating this process. In this paper, we investigate the role of these mediators in the regulation of P-gp functionality and hence the acquisition of MDR following cell to cell transfer. By sequentially silencing the FERM domain-binding proteins, Ezrin, Radixin and Moesin (ERM), as well as CD44, which we also report a selective packaging in breast cancer derived EVs, we have established a role for these proteins, in particular Radixin and CD44, in influencing the P-gp-mediated MDR in whole cells. We also report for the first time the role of ERM proteins in the vesicular transfer of functional P-gp. Specifically, we demonstrate that intercellular membrane insertion is dependent on Ezrin and Moesin, whilst P-gp functionality is governed by the integrity of all ERM proteins in the recipient cell. This study identifies these candidate proteins as potential new therapeutic targets in circumventing MDR clinically.

Highlights

Extracellular vesicles (EVs) comprise one of the many modes of cell-to-cell communication in both prokaryotic and eukaryotic organisms [1,2]
Radixin and CD44 are required for regulating P-gp drug efflux in resistant breast cancer cells at a functional level
Given the role of the FERM domain-binding proteins and CD44 in P-gp membrane localisation in whole cells and their presence in extracellular vesicles (EVs) derived from resistant cells, we examined the role of these proteins in regulating P-gp functionality in resistant breast cancer cells as well as in the intercellular transfer of functional P-gp by microvesicles

Summary

Introduction

Extracellular vesicles (EVs) comprise one of the many modes of cell-to-cell communication in both prokaryotic and eukaryotic organisms [1,2]. They serve as vehicles for the exchange of proteins and nucleic acids, and have been shown to confer cancer traits, including multidrug resistance (MDR) and an enhanced metastatic capacity, in cancer cells [1,3,4,5,6,7]. EVs derived from drug-resistant cancer cells transfer these integral plasma membrane proteins to recipient drug-sensitive cells, effectively conferring functional MDR within a matter of hours [3,4]. Our previous proteomic analysis of EVs derived from resistant breast cancer cells identified candidate mediators unique to these

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