外泌体递送角蛋白8小干扰RNA调控下咽癌细胞对5-FU敏感性研究OACSTPCD

OBJECTIVE To investigate the effect and mechanism of action of KRT8 small interfering RNA(si-KRT8)in exosomes derived from patient serum with hypopharyngeal carcinoma on chemosensitivity to 5-fluorouracil(5-FU)in human pharyngeal squamous cell carcinoma FaDu cell line.METHODS The cancerous tissues of hypopharyngeal cancer patients and The serum,cancerous tissues and paracancerous tissues of drug-resistant patients after treatment were collected.A 5-FU-resistant cell line of FaDu(FaDu/R)was constructed for subsequent experiments.Exosomes were isolated from patient serum by ultrafast gradient centrifugation,identified using transmission electron microscopy and Western blot(WB)techniques.si-KRT8 was encapsulated into exosomes(Exosome@si-KRT8)using electroporation technology and subsequently used to treat cells.Real-time fluorescence quantitative PCR(RT-qPCR)and WB were used to detect the expression levels of KRT8 in different tissues,exosomes after electroporation of si-KRT8,and FaDu cells,respectively.Cell counting kit-8(CCK-8),terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay,migration invasion technique and WB were used to detect the effects of Exosome@si-KRT8 on viability,apoptosis,and epithelial-mesenchymal transition of FaDu/R cells.RESULTS The expression level of KRT8 in drug-resistant tissues of hypopharyngeal carcinoma and FaDu/R cells was elevated compared with that in paraneoplastic tissues,cancer tissues and normal FaDu cells(t=15.79,P＜0.01).Isolated patient serum exosomes showed a double membrane structure and expressed both CD63 and TSG101 proteins,and KRT8 expression in exosomes was decreased after electro-transfection with si-KRT8(t=6.70,P＜0.01).Exosome@si-KRT8 inhibited KRT8 protein expression levels in FaDu/R cells(t=123.50,P＜0.01).Compared with the 5-FU group and the 5-FU+Exosome group,Exosome@si-KRT8 was able to inhibit the viability of FaDu/R cells(t=17.07,P＜0.01),promote the level of apoptosis in FaDu/R cells,and inhibit the expression of drug-resistance-associated proteins in FaDu/R cells(P-gp:t=103.20,MDR1:t=238.60,P＜0.01),and Exosome@si-KRT8 was able to suppress the expression of metastasis of FaDu/R cells(t=42.30,t=122.00,P＜0.01)and promoted the expression of E-cadherin while inhibiting the expression level of N-cadherin(t=130.80,t=83.90,P＜0.01).CONCLUSION Serum-derived exosome encapsulation of si-KRT8 enhances chemosensitivity of hypopharyngeal carcinoma cells and its mechanism of action may be related to inhibition of epithelial-mesenchymal transition.