Disruption of Nucleotide Homeostasis by the Antiproliferative Drug 5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside Monophosphate (AICAR)

Johanna Ceschin,Hans Caspar Hürlimann,Christelle Saint-Marc,Delphine Albrecht,Typhaine Violo,Michel Moenner,Bertrand Daignan-Fornier,Benoît Pinson

doi:10.1074/jbc.m115.656017

Abstract

5-Aminoimidazole-4-carboxamide-1-β-D-ribofuranoside monophosphate (AICAR) is a natural metabolite with potent anti-proliferative and low energy mimetic properties. At high concentration, AICAR is toxic for yeast and mammalian cells, but the molecular basis of this toxicity is poorly understood. Here, we report the identification of yeast purine salvage pathway mutants that are synthetically lethal with AICAR accumulation. Genetic suppression revealed that this synthetic lethality is in part due to low expression of adenine phosphoribosyl transferase under high AICAR conditions. In addition, metabolite profiling points to the AICAR/NTP balance as crucial for optimal utilization of glucose as a carbon source. Indeed, we found that AICAR toxicity in yeast and human cells is alleviated when glucose is replaced by an alternative carbon source. Together, our metabolic analyses unveil the AICAR/NTP balance as a major factor of AICAR antiproliferative effects.

Highlights

Aminoimidazole-4-carboxamide-1-␤-D-ribofuranoside monophosphate (AICAR) is a potent anti-proliferative compound, but the basis of its cytotoxicity is poorly understood
Mutations in the AAH1 Gene Are Synthetically Lethal with ade16 ade17 Mutations Resulting in AICAR Accumulation in Vivo—To isolate mutants which are affected by AICAR accumulation, we started from an ade16 ade17 double mutant that constitutively accumulates AICAR (ϳ 1 mM compared with ϳ1 ␮M in the wild-type strain [4])
Growth on Galactose Allows to Bypass AICAR Toxicity in Human Cells—We investigated the effect of AICAr on human HeLa cells propagated in glucose and galactose-containing medium

Summary

Background

AICAR is a potent anti-proliferative compound, but the basis of its cytotoxicity is poorly understood. We identified a mutant form of the phosphatase Pho, named Pho, which can detoxify succinyl-AICAR to succinylAICAR riboside and thereby diminish intracellular AICAR concentration [9] (Fig. 1B) Together, these results established that the riboside forms of AICAR and succinyl-AICAR are not toxic for yeast cells, a situation highly similar to what happens in mammalian cells where the vast majority of AICAR effects are abolished by adenosine kinase inhibitors [1]. These results established that the riboside forms of AICAR and succinyl-AICAR are not toxic for yeast cells, a situation highly similar to what happens in mammalian cells where the vast majority of AICAR effects are abolished by adenosine kinase inhibitors [1] For both yeast and mammalian cells, it was concluded that AICAr riboside had to be metabolized to the monophosphate form to become active and cytotoxic.

Experimental Procedures

Results

Discussion