Regulation of Exosomes-Mediated circNR4A1 on Chemoresistance and Biological Effects of Oral Squamous Cell Carcinoma Cells

Introduction: The current study aimed to construct a circNR4A1 loaded exosome (EXO) nano system for the treatment of oral squamous cell carcinoma (OSCC) and elucidate the related regulation mechanism in chemoresistance and tumor biology. Methods: Exosomes were isolated from the HEK293 cells by the ultracentrifugation method. Then, the purified nanoproduction was characterized and identified by transmission electron microscopy, dynamic light scattering, and Western blot. The hydrophobic circNR4A1 was then loaded into exosomes by the coincubation method. The effects of circNR4A1 on chemotherapy and apoptosis were evaluated in three multiresistant OSCC cell lines. Results: The range of size distribution of the exosomes was found to be 40-170 nm. Positive TSG101 and CD63 expressions were observed, and the expression of calnexin was negative. In the cisplatin group, circNR4A1 could sensitize 67% of cell lines, while circNR4A1-EXO could sensitize 100% of cell lines. In the 5FU group, circNR4A1 could only sensitize 33% of cell lines, while circNR4A1-EXO could sensitize 67% of cell lines. circNR4A1-EXO is involved in multiple signaling pathways, which can not only activate K-RAS/ERK and MDR-1 signaling pathways but activate DNMT-1 gene expression simultaneously. Conclusion: circNR4A1-EXO can increase the sensitivity of OSCC to anticancer drugs, which may be due to the regulation of the K-RAS/ERK and p53 signaling pathway.