PRKCA and ABCB1 dual-enriched exosomes are key drivers of drug resistance in chronic myeloid leukemia.

AIMS Drug resistance frequently results in treatment failure for leukemia and leads to the progression of chronic myeloid leukemia (CML) into an accelerated or blast phase. An increasing number of CML cases exhibit reduced responsiveness or are refractory to tyrosine kinase inhibitors and chemotherapeutic drugs. Exosomes, as intercellular communication carriers, have been shown to participate in various forms of tumor drug resistance, but their role and mechanisms in CML drug resistance have not yet been fully investigated.

METHODS Exosomes were isolated from the cell culture medium or plasma using ultracentrifugation. RNA sequencing, LC-MS proteomics, Western blot, molecular docking, co-immunoprecipitation, cell viability assay, and flow cytometry analysis were carried out to examine the mechanisms of exosomes in CML drug resistance. Cell line-derived and patient-derived xenografts were estimated to verify the mechanisms of exosomes in CML drug resistance in vivo. Clinical samples from CML patients were used to analyze the predictive potential of exosomes in CML drug resistance.

RESULTS Drug-resistant CML cell-derived exosomes promote multifaceted resistance to imatinib and doxorubicin by directly disseminating the ATP-binding cassette subfamily B member 1 (ABCB1) efflux pump to initially sensitive cells and indirectly upregulating ABCB1 expression, enhancing drug expulsion and resistance. The specific binding regions between ABCB1 with protein kinase C-alpha (PRKCA) that is required for dual-enriched exosomal packaging and ABCB1-mediated resistance. We identified myristoylated alanine-rich C kinase substrate (MARCKS) regulation of PRKCA is an essential prerequisite to PRKCA-ABCB1 interaction, forming a tri-protein complex in drug-resistant CML cells that selectively enriches PRKCA and ABCB1 into exosomes. Mechanistically, exosomes enriched with both PRKCA and ABCB1 enhance fatty acid metabolism through PRKCA, activate the AGE-RAGE signaling pathway, and subsequently upregulate the transcription factors ETS1 and FOXA1. This process leads to increased expression of PRKCA and ABCB1 in drug-sensitive cells, which further contribute to drug efflux and drug resistance in CML cells. Clinically, plasma exosomal PRKCA and ABCB1 together accurately predict drug resistance in CML patients.

CONCLUSIONS PRKCA and ABCB1 dual-enriched exosomes are key drivers of drug resistance in CML patients, and exosomal PRKCA and ABCB1 may serve as diagnostic and therapeutic targets for CML.