Fig 2: NDRG1 is highly expressed in bladder cancer. (A) NDRG1 mRNA and (C) protein expression in bladder cancer tissues was examined by real-time PCR and western blot analyses; n = 15, paired t-test, *p < 0.05, **p < 0.01. T: bladder tumour tissue, N: paired tumour-free tissue. (B) A meta-analysis of NDRG1 mRNA expression from three Oncomine datasets; LSD test, **p < 0.0001.

Fig 3: NDRG1 enhances the motility of bladder cancer cells. (A) After transfection, upregulated expression of NDRG1 promotes the migration of 5637 cells, and downregulated expression of NDRG1 suppresses the migration of 5637 cells and (C) T24 cells; n = 5, *p < 0.05, **p < 0.01, ***p < 0.0001. (B) NDRG1 expression affects the invasive ability of 5637 cells and (D) T24 cells; n = 5, **p < 0.01.

Fig 4: Pathological sections from bladder cancer patients were examined by immunochemistry. (A) Low expression of NDRG1 in tumour-free tissue; (B) Low expression of NDRG1 in NMIBC tissue; High expression of NDRG1 in (C) NMIBC and (D) MIBC tissue. NMIBC: non-muscle-invasive bladder cancer, MIBC: muscle-invasive bladder cancer. 200 × magnification. (E) The immunostaining score of NDRG1 protein expression in bladder cancer; LSD test, Normal group as the control, **p = 0.00738, ***p = 0.000049. NMIBC group as the control, #p = 0.0211.

Fig 5: The diagnostic value of urine NDRG1 levels in bladder cancer patients. (A) The level of urine NDRG1 was measured in patients with NMIBC and MIBC and in healthy controls (healthy control vs. NMIBC: *p < 0.05; healthy control vs. MIBC: **p < 0.01; NMIBC vs. MIBC: #p < 0.05). NMIBC: non-muscle-invasive bladder cancer, MIBC: muscle-invasive bladder cancer. (B) ROC analysis using NDRG1 to distinguish bladder cancer patients from healthy controls. ROC: Receiver operating characteristic. The area under the curve of NDRG1 expression to diagnose bladder cancer was 0.909 (95% CI, 0.829–0.989).