347P Long-term outcomes of initial local therapy for oligorecurrence in resected EGFR-mutated lung adenocarcinoma

compared with the control group and exosomes of A549 cells group.The miRNA sequencing results showed that miR-4746-5p was significantly overexpressed in the exosomes of PC14/B cells.Compared with HBMECs, the intercellular permeability of miR-4746-5p mimics HBMECs was significantly increased, and the expression of tight junction proteins was down-regulated.Conclusions: Exosomes of brain metastasis-prone cells could significantly downregulate the expression of tight junction proteins between HBMECs, thereby disrupting BBB and increasing its permeability, thus promoting the formation of lung cancer brain metastases.Exosomal miR-4746-5p may be involved in the regulation of brain metastasis, but the specific mechanisms remain to be further clarified.