Analysis On The Effects Of Exosomes On Chemotherapeutic Drug Resistance In Nasopharyngeal Carcinoma Cells

Objective:To examine the roles of exosomes as mediators of cisplatin resistance in nasopharyngeal carcinoma cells.Methods:The CNE-1 nasopharyngeal carcinoma cell line was used to establish a cisplatin-resistant cancer cell line through a combination of an increasing cisplatin concentration gradient and high-dose drug shock.Successful drug-resistant cell line establishment verified through morphological observations,CCK-8 assay-mediated drug resistance index calculations,and the measurement of drug resistance-related proteins by Western blotting.Established drug-resistant cells were co-cultured with drug-sensitive cells in a Transwell chamber,with cellular drug resistance being assessed via CCK-8 assay.Exosomes were isolated by differential centrifugation and analyzed via transmission electron microscopy（TEM）and a nanoparticle tracking analysis（NTA）,with Western blotting being used to detect the characteristic exosomal marker proteins TSG101,CD9,and CD81.Exosomes were stained with PKH67 and co-cultured with drug-sensitive cells.The uptake of exosomes by these cells was observed via confocal microscopy.Differential gene expression of exosomes was detected,mir-424mimics was transfected,and FASN expression level of cells was detected.Results:The drug-resistant CNE-1/DDP nasopharyngeal carcinoma cell line exhibited a drug resistance index of 5.15.Under microscopic examination,drug-sensitive cells appeared regular and round in shape,whereas drug-resistant cells were irregular and fusiform or polygonal,with high levels of drug resistance-related MVP and P-gp protein expression.After co-culture,the drug resistance index of sensitive cells was 1.98,without any obvious morphological change,and the levels of drug resistance protein expression were higher than those observed in drug-sensitive cells.TEM revealed exosomes to be circular particles 30-150nm in diameter enclosed by a lipid bilayer membrane.NTA analyses revealed the exosome concentration to be 2.2x10¹¹particles/m L,with an average diameter ranging from 50-150 nm.These particles simultaneously expressed TSG101,CD9,and CD81,consistent with successful exosome isolation.PKH67-labeled green fluorescent exosomes were monitored via confocal microscopy and were found to be readily internalized by CNE-1 cells.The expression of Mir-424 increased in drug-resistant cell exosomes,and the expression level of FASN decreased after transfection of Mir-424 mimics.Conclusion:Drug-resistant nasopharyngeal carcinoma cells can promote drug resistance in otherwise drug-sensitive cells via exosome secretion.The reason for this phenomenon may be related to mir-424 carried by exosomes.