Zinc oxide nanoparticles reduce the chemoresistance of gastric cancer by inhibiting autophagy

BACKGROUND: Gastric cancer (GC) is a common malignancy that results in a high rate of cancer-related mortality. Cisplatin (DDP)-based chemotherapy is the first-line clinical treatment for GC therapy, but chemotherapy resistance remains a severe clinical challenge. Zinc oxide nanoparticle (ZnO-NP) has been identified as a promising anti-cancer agent, but the function of ZnO-NP in GC development is still unclear. AIM: To explore the effect of ZnO-NP on chemotherapy resistance during GC progression. METHODS: ZnO-NP was synthesized, and the effect and underlying mechanisms of ZnO-NP on the malignant progression and chemotherapy resistance of GC cells were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, colony formation assays, transwell assays, wound healing assays, flow cytometry, and Western blot analysis in GC cells and DDP-resistant GC cells, and by tumorigenicity analyses in nude mice. RESULTS: Our data revealed that ZnO-NP was able to inhibit proliferation, migration, and invasion and induce apoptosis of GC cells. Meanwhile, ZnO-NP significantly reduced the half maximal inhibitory concentration (IC(50)) of DDP for the inhibition of cell proliferation of DDP-resistant SGC7901/DDP cell lines. Autophagy was increased in DDP-resistant GC cells, as demonstrated by elevated light chain 3-like protein 2 (LC3II)/LC3I and Beclin-1 expression and repressed p62 expression in SGC7901/DDP cells compared to SGC7901 cells. Mechanically, ZnO-NP inhibited autophagy in GC cells and treatment with DDP induced autophagy, which was reversed by ZnO-NP. Functionally, ZnO-NP attenuated the tumor growth of DDP-resistant GC cells in vivo. CONCLUSION: We conclude that ZnO-NP alleviates the chemoresistance of GC cells by inhibiting autophagy. Our findings present novel insights into the mechanism by which ZnO-NP regulates the chemotherapy resistance of GC. ZnO-NP may serve as a potential therapeutic candidate for GC treatment. The potential role of ZnO-NP in the clinical treatment of GC needs clarification in future investigations.