Study on the Chemotherapeutic Effect and Mechanism of Doxorubicin Hydrochloride on Drug-Resistant Gastric Cancer Cell Lines Using Metal-Organic Framework Fluorescent Nanoparticles as Carriers
Authors: Lv Xianmei , Guo Qiusheng , Xu Liming 
Published: December 2020

Objective. To prepare a polyethylene glycol- (PEG-) modified rare earth metal-organic framework material drug delivery system, obtain DOX@Eu (BTC) fluorescent nanoparticles after loading doxorubicin (DOX), and explore the effect of DOX@Eu (BTC) fluorescent nanoparticles on the chemotherapy sensitivity of gastric cancer multidrug-resistant cells SGC7901/ADR. Methods. The rare earth metal-organic framework fluorescent nanoparticles EU (BTC) were prepared by the solvent method and modified with PEG, and DOX@Eu (BTC) fluorescent nanoparticles were obtained after loading DOX. The particle size distribution of the prepared nanoparticles was analyzed by TEM, the adsorption performance of the prepared nanoparticles was evaluated by BET, the effective drug loading of DOX in the nanoparticles was determined by TGA analysis, and the pH response release performance was evaluated by in vitro release experiments. The MTT method was used to test the toxicity of EU (BTC) to GES-1 and SGC7901/ADR cells and detect the proliferation of SGC7901/ADR cells in each group. A fluorescence confocal microscope was used to observe the positioning of DOX@Eu (BTC) in SGC7901/ADR cells. The expression level of miR-185 in each group of cells was detected by RT-qPCR. The Annexin V-FITC/PI method was used to determine the apoptosis rate of cells in each group. The expression of MRS2 and related drug resistance proteins in each group of cells was detected by Western blotting (WB). The dual-luciferase reporter gene experiment was used to verify the targeting relationship between miR-185 and MRS2. Results. Most of the prepared EU (BTC) fluorescent nanoparticles have a particle size between 50 and 200 nm and have good adsorption capacity. The effective drug loading of DOX is 29%, and it has pH-responsive release performance and can be used in acidic environments. DOX was immobilized in EU (BTC) fluorescent nanoparticles, and DOX@Eu (BTC) fluorescent nanoparticles were present in the cytoplasm or cell membrane of SGC7901/ADR cells. Compared with DOX, DOX@Eu (BTC) fluorescent nanoparticles have stronger cytotoxicity to SGC7901/ADR cells, which also effectively inhibited the expression of multidrug resistance proteins in cells. The expression level of miR-185 in SGC7901/ADR cells decreased, but the expression level of MRS2 protein in SGC7901/ADR cells increased. miR-185 and MRS2 proteins are closely related to the multidrug resistance of SGC7901/ADR cells, and MRS2 is the downstream target gene of miR-185. After the treating of SGC7901/ADR cells with DOX@Eu (BTC) fluorescent nanoparticles, the expression of miR-185 in the cells increased significantly, while the expression of MRS2 protein decreased significantly, and the magnitude of the change was more obvious than that of DOX treatment. Overexpression of miR-185 (miR-mimics) or inhibition of MRS2 (si-MRS2) enhanced the inhibitory effect of DOX@Eu (BTC) fluorescent nanoparticles on the proliferation of SGC7901/ADR cells, which significantly increased the induction of apoptosis by DOX@Eu (BTC) fluorescent nanoparticles, and simultaneous enhanced the inhibitory effect on the expression level of multidrug resistance protein. However, overexpression of miR-185 and MRS2 (pc-MRS2+miR-mimics) at the same time did not affect the chemotherapy sensitivity of SGC7901/ADR cells to DOX@Eu (BTC) fluorescent nanoparticles. However, simultaneous transfection of miR-185 mimics and pc-MRS2 did not affect the chemotherapy sensitivity of SGC7901/ADR cells to DOX@Eu (BTC) fluorescent nanoparticles. Conclusion. DOX@Eu (BTC) fluorescent nanoparticles can effectively enhance the chemotherapy sensitivity of SGC7901/ADR cells to DOX, which may be achieved by upregulating the expression of miR-185 in SGC7901/ADR cells and then inhibiting the expression of MRS2 protein.