Development of a method to study the activity and selectivity of SGLT2 inhibitors / 药学学报

ABSTRACT

The purpose of this study was to develop a screening method to determine the activity and selectivity of SGLT2 inhibitor. Human SGLT1/SGLT2 cDNA was inserted into the pMSCVpuro mammalian expression vector and the plasmid was transfected into HEK293 cells. Stably transfected clones were selected in puromycin containing medium. To evaluate the expression of human SGLT1 and SGLT2 in stable transfected cells, RT-PCR, Western blot and immunofluorescence analysis were performed. 1-[N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-1-deoxy-D-glucose (1-NBDG) was used as a substrate in the uptake assay to evaluate the Na+ dependent glucose transport activities of SGLT1/2. The inhibitory activity and selectivity of dapagliflozin/phloridzin were also determined, respectively. The hypoglycemic efficacy of dapagliflozin was evaluated in mice with normal blood glucose and mice with alloxan-induced T1DM. The result showed that SGLT1 was overexpressed in pMSCVpuro-SGLT1 transfected HEK293 cells. SGLT2 protein was overexpressed in pMSCVpuro-SGLT2 transfected HEK293 cells and located in both cytoplasm and membrane. The Na+ dependent 1-NBDG uptake was significantly increased in pMSCVpuro-SGLT1/SGLT2 transfected cells compared to that in pMSCVpuro-null transfected cells. The selectivity of dapagliflozin, whose half maximal inhibitory concentration (IC50) for SGLT2 (2.24×10-10 mol·L-1) was far lower than that for SGLT1 (6.20×10-7 mol·L-1), was better than that of phloridzin. The oral glucose tolerance was elevated after a single dose of dapagliflozin in normal mice. In T1DM mice, compared with model group, no-fasting glucose level was decreased at 1 h after administration and maintained at a lower level for 24 h in a dose-dependent manner. A 20-day administration with dapagliflozin dose-dependently improved the hyperglycemia status. Taken together, a system to evaluate the activity and selectivity of SGLT2 inhibitors was established using 1-NBDG in vitro and the hypoglycemic efficacy in vivo in this study. The advantages of this system include non-radioactivity, high efficiency, and good stability which may provide a technique platform for development of novel SGLT2 inhibitors.