Release of exosomes have been shown to play critical roles in drug resistance by delivering cargo. Targeting the transfer of exosomes from resistant cells to sensitive cells may be an approach to overcome some cases of drug resistance.
In this study, researchers from Binzhou Medical University investigated the potential role of exosomes in the process of psoralen reverse multidrug resistance of MCF-7/ADR cells. Exosomes were isolated by differential centrifugation of culture media from MCF-7/ADR cells (ADR/exo) and MCF-7 parental cells (S/exo). Exosomes were characterized by morphology, exosomal markers and size distribution. The ability of ADR/exo to transfer multidrug resistance was assessed by MTT and real-time quantitative PCR. The different formation and secretion of exosomes were detected by immunofluorescence and transmission electron microscopy. Then the researchers performed comparative transcriptomic analysis using RNA-Seq technology and real-time quantitative PCR to better understand the gene expression regulation in exosmes formation and release after psoralen treatment.
These data showed that exosomes derived from MCF-7/ADR cells were able to promote active sequestration of drugs and could induce a drug resistance phenotype by transferring drug-resistance-related gene MDR-1 and P-glycoprotein protein. Psoralen could reduce the formation and secretion of exosomes to overcome drug resistance. There were 21 differentially expressed genes. Gene ontology (GO) pathway analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the most significantly expressed genes were linked to PPAR and P53 signaling pathways which were related to exosomes formation, secretion and cargo sorting.
ADR/exo transfer chemoresistance to recipient cells
a The uptake of the fluorescently labelled Exo/ADR was evident in 90% MCF-7 cells after 12 h of incubation. No stain was revealed in the negative control condition (PBS). b Drug-resistance-related mRNA changes (MDR-1, MRP and LRP) in MCF-7 incubated with ADR/exo. ADR/exo induced a increase of MDR-1, MRP and LRP mRNA levels compared to MCF-7 and MCF-7 + S/exo cells, especially the MDR-1 (p < 0.05). c IC50 of adriamycin was determined by MTT. The results showed that MCF-7 cells after incubation with ADR/exo displayed 5.5 fold greater resistance to adriamycin than MCF-7 cells. MCF-7 + ADR/exo had greater resistance to adriamycin, p < 0.05 compared to MCF-7 cells. d Confocal micrographs showing adriamycin localization in MCF-7+ ADR/exo cells. Scale bars, 25 μm