AS1842856, a cell-permeable inhibitor, can block the transcription activity of Foxo1 (IC50: 33 nM). It can directly bind to the active Foxo1, but not the Ser256-phosphorylated form.

AS1842856 predominantly suppresses Foxo1-mediated transactivation by directly binding to Foxo1. In HepG2 cells transiently transfected with a Foxo1 expression vector, AS1842856 potently represses Foxo1-mediated promoter activity in a dose-dependent manner similar to that seen in insulin treatment.AS1842856 administered at 0.1 μM inhibits Foxo3a- and Foxo4-mediated promoter activity by 3 and 20%, respectively. In contrast, Foxo1-mediated promoter activity is decreased by 70%. Foxo1 inhibitor AS1842856 may suppress endogenous G6Pase and PEPCK activities by decreasing their mRNA levels, which may lead to inhibition of glucose production in Fao cells[1].

Administering AS1842856 orally to diabetic db/db mice significantly reduces the fasting plasma glucose levels by suppressing hepatic gluconeogenic genes. However, this compound does not alter fasting plasma glucose levels in normal mice. Additionally, AS1842856 prevents the rise in plasma glucose levels following pyruvate injection in both normal and db/db mice[1].

Fao cells are serum-starved (1 h) and incubated for 30 min with either insulin or AS1842856 at the indicated concentration. Protein lysates are prepared from cells treated with either insulin or AS1842856, and relative concentration of phosphorylated Foxo1 protein is determined by Western blot analysis. (Only for Reference)