Objective: To study the effect of 1

25-(OH)2-VitD3 on the proliferation of bladder cancer cells and explore its mechanism. Methods: Bladder cancer cells T24 were cultured in vitro. The effects of 1

25-(OH)2-VitD3 at different concentrations on cell viability were detected by MTT assay. The optimal time and half inhibitory concentration of 1

25-(OH)2-VitD3 on bladder cancer cells were screened. Cells were divided into four groups: control group

glucose transporter-1 (GLUT1) inhibitor group

1

25-(OH)2-VitD3 group and 1

25-(OH)2-VitD3+GLUT1 inhibitor group. Hoechst 33258 staining was used to observe the morphological changes of cells in each group. The levels of glucose uptake

adenosine triphosphate (ATP) production and lactate formation were detected by kits. The mRNA and protein expression levels of GLUT1

hexokinase 2 (HK2)

6-phosphofructo-2-kinase/fructose-2

6-biphosphatase 3 (PFKFP3)

pyruvate kinase isozyme type M2 (PKM2)

lactate dehydrogenase A (LDHA) and hypoxia-inducible factor-1α (HIF-1α) were detected by real-time PCR and Western blot. Results: 1

25-(OH)2-VitD3 could reduce the proliferation of T24 cells in a dose-dependent manner. The number of apoptotic cells in 1

25-(OH)2-VitD3 group

GLUT1 inhibitor group and 1

25-(OH)2-VitD3+GLUT1 inhibitor group were higher than that in control group

while the mRNA and protein expression levels of GLUT1

HK2

PFKFP3

PKM2

LDHA and HIF-1α were significantly lower than those in control group. Compared with GLUT1 inhibitor group

the mRNA (all P=0.000) and protein (all P=0.000) expression levels of GLUT1

HK2

PFKFP3

PKM2

LDHA and HIF-1α were significantly lower in 1

25-(OH)2-VitD3+GLUT1 inhibitor group. Conclusion: 1

5-(OH)2-VitD3 can inhibit the proliferation and induce apoptosis of bladder cancer cells. Its mechanism may be related to down-regulation of GLUT1 expression to inhibit cell glucolusis.