Cisplatin-resistant MDA-MB-231 Cell-derived Exosomes Increase the Resistance of Recipient Cells in an Exosomal MiR-423-5p-dependent Manner

(E-pub Ahead of Print)

Author(s): Bing Wang*, Yuzhu Zhang, Meina Ye, Jingjing Wu, Lina Ma, Hongfeng Chen*.

Journal Name: Current Drug Metabolism


Background: Chemoresistance blunts the therapeutic effect of cisplatin (DDP) on triple-negative breast cancer (TNBC). Researchers have not determined to date whether exosomes confer DDP resistance to other breast cancer cells or whether the exosomal transfer of miRNAs derived from DDP-resistant TNBC cells confers DDP resistance.

Objective: The aim of this study was to investigate the role of exosomes in chemoresistance in breast cancer.

Methods: MDA-MB-231 cells resistant to DDP (231/DDP) were established. Exosomes were isolated from 231/DDP cells (DDP/EXO) and characterized by measuring the levels of protein markers, performing a nanoparticle tracking analysis and transmission electron microscopy. The MDA-MB-231, MCF-7, and SKBR-3 cell lines were treated with the isolated DDP/EXOs and cell proliferation and cytotoxicity to DDP were evaluated using MTT assays and apoptosis analyses. Western blotting was used to examine P-gp expression. Additionally, a microarray was used to analyse microRNA (miRNA) expression profiles in MDA-MB-231 and 231/DDP exosomes. The effects on miRNAs were determined using RT-PCR. Exosomal miR-423-5p was extracted, and differential expression was verified. The MTT cell viability assay, flow cytometry, and Transwell and immunofluorescence assays were performed to determine if the differential expression of miR-423-5p sensitized cells to DDP in vitro.

Results: Under a transmission electron microscope, the isolated exosomes exhibited a round or oval shape with a diameter ranging between 40 and 100 nm. DDP/EXOs labelled with PKH67 were taken up by MDA-MB-231 cells. After incubation with DDP/EXOs, the cell lines exhibited a higher IC50 value for cisplatin, P-gp expression, migration and invasion capabilities, and a lower apoptosis rate. Furthermore, 60 miRNAs from exosomes derived from 231/DDP cells were significantly up-regulated compared to exosomes from MDA-MB-231 cells. Notably, compared to the corresponding sensitive exosomes, miR-370-3p, miR-423-5p, and miR-373 were the most differentially expressed miRNAs in DDP-resistant exosomes. We chose miR-423-5p, and up-regulation and down-regulation of exosomal miR-423-5p expression significantly affected DDP resistance.

Conclusions: Exosomes from DDP-resistant TNBC cells (231/DDP) altered the sensitivity of other breast cancer cells to DDP in an exosomal miR-423-5p dependent manner. Our research helps to elucidate the mechanism of DDP resistance in breast cancer.

Keywords: DDP resistance, exosomes, miR-423-5p, cisplatin, breast cancer

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(E-pub Ahead of Print)
DOI: 10.2174/1389200220666190819151946
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