PK profiles of were evaluated
PK profiles of were evaluated and found to be improved compared to compound presumably due to interruption of β-oxidation. Low clearance and high plasma exposure were considered to be suitable profiles as an oral agent ().
We first examined in vitro insulinotropic effects of compound from MIN6 cells., The significant increases of insulin were observed as dose dependently from 0.001 to 10μM compound in the presence of 25mM glucose ().
Next, the glucose lowering effect of compound was evaluated by an oral glucose tolerant test (OGTT) in diabetic Zucker fatty rats (). Compounds were administrated orally in 9-week-old Zucker fatty rats 30min prior to the glucose challenge. Compound significantly reduced blood glucose excursion in a dose dependent manner with doses ranging from 1 to 10mg/kg. Sitagliptin, a marketed DPP-4 inhibitor, was included as a positive control in this study. Compound at a dose of 3mg/kg showed similar efficacy to sitagliptin at a dose of 10mg/kg, therefore the potency of compound was seemed to be as 3-fold strong as sitagliptin. As shown in , robust increase of insulin secretion was also observed. During this test, exposure of compound was sufficient to exhibit potent in vivo efficacy ().
Finally, We confirmed that compound was inactive up to 10μM on GPR120 and PPAR α,γ,δ receptors,, which have also the fatty acids as their ligands.
In conclusion, we discovered a series of propanoic RSL3 derivatives as a lead structure for potent and orally bioavailable GPR40 agonists. Starting from compound , introduction of substituents on propanoic acid moiety improved the PK profiles, and removal of the biphenyl structure lowered the toxicity risks. Among them, compound was found to be a promising lead compound. Compound increased insulin secretion from MIN6 cells and lowered plasma glucose level in rat OGTT. Further optimization on this series is ongoing and will be reported in due course.
MIN6 cells were licensed in from Prof. Jun-ichi Miyazaki at Osaka University. We thank Prof. Miyazaki and the staffs at his laboratory for their assistance in the use of MIN6 cells and useful advice.
Introduction Free fatty acids (FFAs) are dietary nutrients and essential energy sources. Fatty acids are classified by the length of carbon chains. Short-chain fatty acids have fewer than 6 carbons, medium-chain fatty acids have 6 to 12 carbons and long-chain fatty acids contain more than 12 carbons , , . FFAs act as extracellular signaling molecules through binding to FFA receptors (FFARs), which belong to a family of G-protein-coupled transmembrane receptors , , . Among FFARs, GPR120 and GPR40 are functionally activated by long- and medium-chain FFAs , , . However, the distribution and biological response of GPR120 and GPR40 are not uniform. High expression of GPR120 is found in gastrointestinal tract, lung, adipocytes and macrophages, suggesting that GPR120 is involved in the regulation of metabolism and immune response , , . On the other hand, pancreatic beta cells highly expressed GPR40 in pancreatic tissues, suggesting that GPR40 stimulates insulin secretion . Moreover, GPR40 expression was highly detected in insulinoma cells, but not in glucagonoma cells . In colorectal carcinoma cells, activated GPR120 increased cell motile activity and angiogenesis process . Recently, we showed that GPR120 enhanced and GPR40 suppressed cell motile activity of liver epithelial cells treated with chemical agents , . In the present study, we investigated the roles of GPR120 and GPR40 in cellular functions of pancreatic cancer cells. HPD1NR and HPD2NR cells used in this study were established from hamster pancreatic duct adenocarcinomas . In addition, GPR120 and GPR40 knockdown cells were generated from human pancreatic PANC-1 cells.
Materials and methods
Results and discussion