NPC intracellular cholesterol transporter 2 regulates the anti-apoptotic protein baculoviral inhibitor of apoptosis repeat containing 3 and affects drug resistance in gastric cancer.

OBJECTIVE: Cisplatin (DDP)-based chemotherapy medications are frequently used as the initial line of treatment for cancer patients, including those with stomach cancer. At present, DDP resistance is a frequent problem in chemotherapy for advanced gastric cancer (GC). This study aimed to investigate the function of NPC intracellular cholesterol transporter 2 (NPC2) in GC cells. MATERIAL AND METHODS: The expression of NPC2 and baculoviral inhibitor of apoptosis repeat containing 3 (BIRC3) in gastric epithelial cells-1, BGC823, and BGC823/DDP cells was determined by Western blotting and quantitative real-time polymerase chain reaction, respectively. Subsequently, the proliferative capacity and viability of BGC823 cells were assessed by 3-(4,5-dimethylthiazol2-yl)-2.5-diphenyl-2-tetrazolium bromide, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay, and colony-formation assay. Finally, the association of NPC2 and BIRC3 with the nuclear factor kappa-B (NF-κB) pathway was determined by Western Blot. RESULTS: In GC cells, NPC2 transcription increased, and DDP-resistant cells showed higher NPC2 expression levels than their parental cells (P < 0.001). In terms of mechanism, compared with parental cells, overexpressing NPC2, DDP-resistant cells showed resistance to DDP. Knocking down NPC2 increased the apoptotic response of DDP-resistant cells to DDP and blocked the cancer cells resistant to DDP exhibiting BIRC3, thereby promoting GC cell apoptosis (P < 0.001). Importantly, involving NF-κB signaling overturned the NPC2-mediated DDP resistance. CONCLUSION: NPC2 regulated BIRC3 and affected drug resistance in GC. Therefore, NPC2 and BIRC3 may be new targets for cancer patient treatment following DDP therapy and act as roadblocks to overcome chemotherapy resistance in GC.