Chemotherapeutic resistance leads to high mortality among triple negative breast cancer (TNBC) patients and underlying mechanisms are poorly understood. Exosomes have become new area of interest for liquid biopsy. MicroRNAs (miRNAs), as the most important inclusions in exosomes, are ideal candidate biomarkers and therapeutic targets.
We isolated exosomes and analyzed exosome-carried miRNA signatures in several TNBC cells lines sensitive or resistant to adariamycin, docetaxel or cisplatin. The resistance transfer capacity was determined by flow cytometry after sensitive cells incubated 48 hours with exosomes from drug-resistant cells. Locked nucleic acid probes and enzyme-labeled fluorescence (LNA-ELF-FISH) was performed to detect exosomal miRNA molecule transfer. Animal mode was constructed to evaluate treatment feasibility using miRNA-modified exosomes. Serum exosomes from 40 TNBC stage IV patients who underwent chemotherapy before or after progressive disease (PD) status were isolated to analyze miRNA profiling for potential biomarker identification.
We successfully isolated and identified exosomes from several drugsensitive and resistant TNBC cell lines and patients. Exosomal miR-222, miR-4443, miR-100, miR-17, miR-210 were found significantly upregulated from chemotherapy-resistant cells. Incubation of exosomes from the resistant cells with the sensitive cells resulted in increasing resistant capacity among sensitive cells. Exosomal miRNA molecule transfer was detected using LNA-ELF-FISH. Transfection of synthesized miRNAs competitors into exosomes increased drug sensitivity in vivo. Exosomal miR-222, miR-4443, miR-100, miR-17, miR-210 were also found upregulated significantly from serums of patients after PD status. These five miRNAs were able to differentiate patients with PD status from those with CR or PR status with at least 89% accuracy.
Exosomes from chemotherapy-resistant TNBC cells could transfer drug resistance to sensitive cells via exosomal miRNAs. A circulating exosomal microRNA profiling was estabilished for potential biomarkers and therapeutic target identification.
Clinical trial identification
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All authors have declared no conflicts of interest.