1, 25-(OH)2-VitD3 inhibits the proliferation of bladder cancer cells by down-regulating the expression of glucose transporter-1

Abstract:

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.