Abstract
Drug resistance in chemotherapy has been greatly challenging for cancer treatment. Research has revealed that extracellular vesicles (EVs) secreted by drug-resistant cells could induce chemoresistance in susceptible cells. However, there are few ways to give direct evidence of it. Herein, we have proposed a microchip-based system to study the drug resistance of a wild-type human lung adenocarcinoma cell line (A549/WT) induced by EVs derived from A549/DDP cells that are resistant to cisplatin (DDP) inherently. EVs derived from A549/DDP were proved to be the crucial factor that enhanced the resistance of A549/WT to DDP through live and dead cell staining, cell viability testing, and immunofluorescence of P-glycoprotein in the off-chip assay. Then, it was further validated that drug resistance of A549/WT cells to DDP significantly increased after being cocultured with A549/DDP cells within 96 h in the on-chip assay. These findings proved that the change of A549/WT drug resistance was caused by intercellular interaction, which was mainly mediated by EVs. In addition, we successfully reversed the EV-induced drug resistance of A549/WT cells by combining DDP and metformin, a hypoglycemic drug with low cytotoxicity when used alone. This microchip system provides a novel tool that has great potential for the investigation of cell interaction, drug resistance, and the tumor microenvironment in fundamental and clinical medicine.