Exosomal proteomics reveals fatty acid metabolism linked to gefitinib resistance in non-small cell lung cancer

Exosomes play a crucial role in the transmission of drug resistance in tumors. However, the mechanism of exosomes-mediated transmission in non-small cell lung cancer (NSCLC) under gefitinib treatment remains limited. In this work, we demonstrated that exosomes derived from HCC827/GR cells (drug-resistant) enhanced the survivability of HCC827 cells (drug-sensitive) under treatment with gefitinib. A total of 157 shared upregulated proteins between exosomes and their parent cells were identified in the comparison of the gefitinib-resistant groups versus the gefitinib-sensitive groups. Notably, 69 of these shared proteins are enzymes, and many of them were enriched in pathways related to fatty acid metabolism. Among these enzymes involved in fatty acid metabolism, ACC1 exhibited the highest fold change in upregulated expression in both drug-resistant groups (exosomes and cells). Moreover, the expression of ACC1 was upregulated in gefitinib-sensitive cells after uptake of exosomes from gefitinib-resistant cells. The role of ACC1 in enhancing the survival of HCC827/GR cells under gefitinib treatment was demonstrated using an inhibitor and siRNA-mediated knockdown. Specifically, the upregulated ACC1 stabilized fatty acid oxidation and reactive oxygen species levels in HCC827/GR cells, thereby maintaining cellular metabolic homeostasis. Collectively, this work reveals the transmission of drug resistance in NSCLC via exosomes that carry the ACC1 protein.