Tami-14. Reduction in S. Cerevisiae Growth and Cell Viability in Response to D-2-Hydroxyglutarate Accumulation Is Dampened by Growth Conditions Permissive of Oxidative Phosphorylation

Abstract

BACKGROUND Elevated levels of D-2-hydroxyglutarate (D2HG) have been detected in several cancers, including IDH1/2 mutant gliomas, PHGDH-amplified breast cancer, diffuse large B-cell lymphomas which harbor loss-of-function mutations in D2HG dehydrogenase gene (D2HGDH), and MYC-amplified breast cancers. Given the high degree of conservation between the yeast and human isocitrate dehydrogenases the similarities between yeast and cancer glycolytic metabolism, we hypothesized that a yeast model would allow for the successful recapitulation of metabolic dysregulation by D2HG. METHODS A heteroallelic idp1 R148H yeast strain was created (equivalent to human IDH2 R172H). The growth characteristics of this strain and the dld3∆ strain (equivalent to D2HGDH loss of function) were evaluated with glucose or galactose carbon source. Octyl-D2HG, a cell permeable mimic of D2HG, was used to assess the effects of D2HG accumulation at varying concentration. FACS was used to measure cell viability, reactive oxygen species (ROS) production, and mitochondrial membrane potential. Analysis of the synthetic lethal genetic array for the dld3∆ strain was performed. RESULTS Accumulation of D2HG in mutant and wild-type yeast strains results in impaired growth and reduction in cell viability in a concentration dependent manner. The negative effect on growth and cell viability is more prominent when cells are not utilizing oxidative phosphorylation for energy production (glucose versus galactose carbon source). D-2HG accumulation results in ROS production in dld3∆ but not in the heteroallelicidp1 R148H yeast strain. An increase in mitochondrial membrane potential occurs in both strains when grown with galactose, but not in glucose. The top negative genetic interactors with dld3∆ include genes involved in mitochondrial function. CONCLUSIONS We found that yeast cells have different sensitivity to the toxic effects of D-2HG depending on the metabolic status of the cell. This suggests that altering cell metabolism may be a viable therapeutic target in cancers with excess production of D2HG such as IDH mutant gliomas.