NXPH4 Promotes Gemcitabine Resistance in Bladder Cancer by Enhancing Reactive Oxygen Species and Glycolysis Activation through Modulating NDUFA4L2

SIMPLE SUMMARY: Bladder cancer is one of the most common malignant tumors of the urinary system, and its treatment is mainly surgical resection, supplemented by chemotherapy after surgery. Postoperative chemotherapy can significantly reduce the tumor recurrence rate and improve the prognosis of bladder cancer patients. However, chemotherapy resistance is one of the major challenges in the treatment of bladder cancer. Therefore, we conducted a series bioinformatic analyses and functional experiments to reveal the novel role of NXPH4 in bladder cancer. We found NXPH4 not only influenced the proliferation, migration, invasion ability of cancer cells, but also affected the level of glycolysis and reactive oxygen species and further promoted the gemcitabine resistance of bladder cancer. Our research has found a novel molecule that may play an important part in the neoplasia, which may provide another angle in the treatment of bladder cancer. ABSTRACT: Bladder cancer is one of the most prevalent kinds of cancer worldwide, and resistance to gemcitabine is a major problem for patients. The pathogenesis of bladder cancer and mechanism of resistance to chemotherapy remain to be explored. Through bioinformatics analysis, we first found that NXPH4 was independently related to the prognosis of patients with bladder cancer. Through wound healing assays, transwell invasion assays, and plate clone formation assays, we found that NXPH4 promoted the proliferation, migration, and invasion of bladder cancer cells. The induced gemcitabine resistance cell line also showed a higher expression of NXPH4. A glycolytic activity assay demonstrated that the expression of NXPH4 was positively related to glycolysis. A higher level of reactive oxygen species caused by enhanced levels of NXPH4 was found in gemcitabine-resistant cell lines. NDUFA4L2, glycolysis, and reactive oxygen species were shown to be essential for NXPH4-regulated functions through rescue assays in cell lines. The roles of NXPH4-regulated glycolysis, gemcitabine resistance, and NDUFA4L2 were validated in vivo as well. Our results imply that NXPH4 contributes to the proliferation, migration, and invasion of bladder cancer by maintaining the stability of NDUFA4L2 and consequently activating reactive oxygen species and glycolysis.