Therapeutic targeting Netrin-1-positive invasive bladder cancer cells with oridonin

Abstract Background Small compound oridonin acts as an effective anti-tumor agent used for a wide variety of human malignancies, while the antitumor efficacy and molecular mechanism of oridonin against bladder cancer remains unclear. Methods Four independent cohorts of bladder cancer were employed to assess the correlation between netrin-1 expression and progression and prognosis of bladder cancer. Clinical potential of netrin-1 as a biomarker and oridonin-mediated netrin-1-targeting anti-tumor mechanism were investigated by QRT-PCR, Western blot and ELISA. Regulatory mechanisms of Netrin-1 were investigated by luciferase reporter assay and Western blot. The EJ-inoculated nude mice xenograft model was used for the in vivo study. Results High expression of netrin-1 was significantly correlated with a poor overall survival in three independent bladder cancer cohorts. Urinary netrin-1 level was significantly elevated in bladder cancer patients correlating with tumor invasion and grade. Netrin-1 promoted cell proliferation, tumorsphere-forming, migration and invasion in bladder cancer cells. Oridonin treatment strikingly suppressed these malignant phenotypes and induced cell death in TCC cell lines and murine xenografts. Oridonin markedly decreased netrin-1 through inhibiting NF-κB transcriptional activity and shortening the half-life of NTN1 mRNA via inducing IRE1α , resulting in repression of its downstream signaling. Conclusions Together, these results strongly suggest that netrin-1 promotes the progression of bladder cancer, and acts as a potential urinary biomarker for the diagnosis as well as the prediction of the tumor progression. Oridonin exerts its strong anti-tumor activity against the invasive bladder cancer by suppressing netrin-1 mRNA production and stability.