Identification of 4-Aminopyrazolopyrimidine Metabolite That May Contribute to the Hypolipidemic Effects of LY2584702 in Long Evans Diet-Induced Obese Rats

J Pharmacol Exp Ther. 2017 Jul;362(1):108-118. doi: 10.1124/jpet.117.240242. Epub 2017 May 2.

Abstract

LY2584702 is an inhibitor of p70 S6 kinase-1 previously developed for the treatment of cancer. In two phase 1 trials in oncology patients, significant reductions of total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglyceride were observed. In the current study, we sought to understand the potential mechanism of action of this compound in regulating lipid metabolism. In Long Evans diet-induced obese (DIO) rats, oral administration of LY2584702 for 3-4 weeks led to robust reduction of LDL-C up to 60%. An unexpected finding of liver triglyceride (TG) increase implicated a metabolite of LY2584702, 4-aminopyrazolo[3,4-day]pyrimidine (4-APP), in modulation of lipid metabolism in these rats. We showed that low-dose 4-APP, when administered orally for 3-4 weeks to Long Evans DIO rats, produced lipoprotein profile changes that were strikingly similar to LY2584702. Kinetic studies suggested that both LY2584702 and 4-APP had no effect on chylomicron-TG secretion and only exerted a modest effect on hepatic very low-density lipoprotein (VLDL)-TG secretion. In human hepatoma HepG2 cells, 4-APP, but not LY2584702, increased LDL uptake. We hypothesize that generation of the 4-APP metabolite may contribute to the efficacy of LY2584702 in lowering LDL-C in rats and potentially in humans as well. This mechanism of LDL-C lowering may include inhibition of VLDL production and increase in LDL clearance.

MeSH terms

  • Adenine / analogs & derivatives*
  • Adenine / pharmacology
  • Animals
  • Cholesterol, LDL / blood
  • Cholesterol, LDL / metabolism
  • Cholesterol, VLDL / biosynthesis
  • Cholesterol, VLDL / genetics
  • Gene Expression Regulation / drug effects
  • Hep G2 Cells
  • Humans
  • Hypolipidemic Agents / pharmacology*
  • Lipid Metabolism / drug effects
  • Lipoproteins, LDL / metabolism
  • Liver / drug effects
  • Liver / metabolism
  • Male
  • Obesity / blood*
  • Pyrazoles / pharmacology*
  • Pyrimidines / pharmacology*
  • Rats
  • Rats, Long-Evans
  • Triglycerides / metabolism

Substances

  • Cholesterol, LDL
  • Cholesterol, VLDL
  • Hypolipidemic Agents
  • Lipoproteins, LDL
  • Pyrazoles
  • Pyrimidines
  • Triglycerides
  • 4-aminopyrazolo(3,4-d)pyrimidine
  • LY2584702
  • Adenine