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S. Zhao



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    MA 11 - Emerging Diagnostic/Biomarkers in NSCLC (ID 668)

    • Event: WCLC 2017
    • Type: Mini Oral
    • Track: Advanced NSCLC
    • Presentations: 1
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      MA 11.07 - Exosomes-Transmitted MicroRNAs Promote EGFR-TKIs Resistance in NSCLC by Activating PI3K/AKT Signaling Pathway (ID 9446)

      11:00 - 12:30  |  Author(s): S. Zhao

      • Abstract
      • Presentation
      • Slides

      Background:
      Acquired epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) resistance is a major factor contributing to targeted therapy failure in EGFR mutant non-small cell lung cancer (NSCLC), among which T790M mutation accounts for 50-60%. Emerging evidence has shown that as mediators between cells, exosomes shed by drug resistant cancer cells have the ability to horizontally transfer drug resistant phenotype to drug sensitive cells, which has been described as an important mechanism of dissemination of drug resistance. However, whether exosomes derived from EGFR-TKIs resistant NSCLC cells harboring T790M mutation could transfer resistance to sensitive cells has not been understood and the potential mechanism also remains unknown.

      Method:
      Exosomes were isolated from supernatants of T790M mutant NSCLC cell line (H1975) and characterized by transmission electron microscopy, nanosight and western blot. Their potential roles in mediating gefitinib resistance in sensitive cell line (PC9) were investigated in vitro and in vivo. Cell viability and the effects of exosomes on downstream signaling pathways were analyzed by CCK-8 assays and western blot. The roles of exosomes in regulating gefitinib resistance in vivo were assessed by subcutaneous transplantation tumor model in athymic nude mice. Exosomes miRNA sequencing and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) were used for exploring the underlying mechanism.

      Result:
      Exosomes isolated from conditioned medium of NSCLC cell lines were cup-shaped membranous vesicles with a diameter of 30-100 nm and expressed the exosomal marker CD63. Exosomes derived from H1975 could transmit gefitinib resistance to PC9 (P＜0.01) in vitro while exosomes released from PC9 cell don’t have this effect. Treatment of PC9 with H1975-derived exosomes and the inhibitor of exosomes production (GW4869) could restore gefitinib response. In vivo, the tumor volume of xenograft model of PC9 cells treated with gefitinib plus H1975-derived exosomes was significantly larger than those mice treated with gefitinib alone (P＜0.05). Furthermore, H1975 xenografts could disseminate gefitinib resistance to PC9 xenografts in the same mice. This difference disappeared by the addition of GW4869. Mechanistically, intercellular transfer of microRNAs (miR-522-3p and miR-454-3p) by exosomes disseminated gefitinib resistance through activating PI3K/AKT and MEK/ERK signaling pathways

      Conclusion:
      Our findings demonstrate that EGFR-TKIs resistant cells could disseminate drug resistance to sensitive cells by intercellular transfer of exosome-transmitted microRNAs and then activating PI3K/AKT and MEK/ERK signaling pathways, which reveals a novel mechanism of acquired resistance to EGFR-TKIs in NSCLC.

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