Metformin, a frontline treatment for T2D, is a BIG drug with low potency and limiting side effects. To overcome these limitations, we examined a compound library of 265 novel BIGs by screening these agents against five organic cationic transporters (OCTs) (OCTs 1, 2 and 3, PMATE and MATE1), an approach based on the need of OCTs for BIG cell entry and action. mRNA expression data from vervet monkey liver, fat and muscle showed OCT1, OCT3, PMAT and MATE1 were the predominate transporters and were used to guide our search for more potent and selective BIGs. BIG transport activity was measured by a decrease in oxygen consumption rate (OCR) in HEK 293 cells that express a single OCT and the results reported as EC50 values. Following the screening, we identified NT1195 from its EC50 transport values of 25, 5, 12, 3 and 57 uM respectively for OCT1, 2 and 3, PMAT and MATE1 when compared to those for metformin of 409, 320, 133, 288 and 5,993 uM. Other cellular effects of NT1195 were then examined in human adipocytes and myotubes, and in H4-lle liver cells. AMPK activation, a basic feature of BIG action, was increased by 6-fold over basal by NT1195 in fat cells versus a 3-fold increase by metformin; the EC50 values were respectively 78 uM and 4,928 uM. NT1195 stimulated AMPK in myotubes by 3-fold with an EC50 of 1,994 uM; metformin stimulation AMPK by 1.8-fold with an EC50 of 7,817 uM. Both agents produced a 2-fold activation of AMPK in H4-II e cells but with different EC50 values of 641 uM for NT1195 and 5,576 uM for metformin. Glucose production by H4-IIe cells was inhibited 90% by both BIGs, whereas the EC50 values were 32 nM for NT1195 and 285 uM for metformin. NT1195 inhibited lipolysis in human fat cells stimulated by isoproterenol by 90% with an EC50 of 286 uM while metformin inhibited lipolysis by 66% with an EC50 of 4,360 uM. Therefore overall, these findings demonstrate the much greater potency of NT1195 over metformin and supports its potential as an improved therapeutic for T2D.
J.N. Livingston: Consultant; Self; CohBar, Inc. Employee; Self; NovoTarg Therapeutics. J.E. Cobb: Consultant; Self; NovaTarg Therapeutics. K.K. Brown: None. K. Kavanagh: Research Support; Self; Takeda Development Centre Europe Ltd. K.W. Batchelor: None.
National Institutes of Health