Exosomal miR-155-5p drives ibrutinib resistance in B-cell lymphoma.

Ibrutinib, a Bruton Tyrosine Kinase (BTK) inhibitor, has shown effectiveness against various B-cell lymphoid malignancies. However, prolonged usage can induce resistance, affecting treatment outcomes. The oncogenic microRNA, miR-155-5p, is associated with poor prognosis in B-cell lymphomas, prompting our investigation into the mechanism of acquired ibrutinib resistance in these cells. We generated ibrutinib-resistant OCI-Ly1 cells (OCI-Ly1-IbtR) through continuous exposure to 1 μM and 2 μM of ibrutinib. We conducted microRNA profiling of OCI-Ly1-IbtR and isolated exosomes via ultracentrifugation. Comparative studies of microRNA levels in cells and exosomes, as well as exploration of targets of up-regulated microRNAs in OCI-Ly1-IbtR, were performed. Target validation involved transfection of candidate microRNAs, and co-culture experiments utilized OCI-Ly1 cells with exosomes from OCI-Ly1-IbtR. Elevated levels of miR-155-5p were observed in OCI-Ly1-IbtR and its exosomes, correlating with AKT and NF-κB activation. Transfection of miR-155-5p induced AKT/NF-κB pathway activation in OCI-Ly1, resulting in ibrutinib resistance, enhanced colony formation, and sustained BTK activity. Primary cell lines from ibrutinib-refractory B-cell lymphoma patients exhibited similar signaling protein activation. Target evaluation identified KDM5B and DEPTOR as miR-155-5p targets, confirmed by downregulation after transfection. We observed KDM5B and DEPTOR enrichment in Ago2 during ibrutinib resistance and miR-155-5p transfection. Co-culture experiments demonstrated exosome-mediated transfer of miR-155-5p, inducing ibrutinib resistance and KDM5B/DEPTOR downregulation in OCI-Ly1. Our findings suggest that miR-155-5p overexpression is associated with AKT and NF-κB pathway activation in ibrutinib-resistant cells, proposing a potential role for acquired miR-155-5p upregulation in B-cell lymphoma ibrutinib resistance.