Glyceraldehyde‐3‐phosphate dehydrogenase differentiates the cytotoxic mechanisms of cancer‐active electrophiles in a yeast model

Abstract

Diverse examples of thiol‐reactive electrophiles, ranging from trivalent arsenicals to 3‐bromopyruvate (3BP), have shown promise as anti‐cancer agents. Inhibition of the glycolytic activity of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) has been identified as a primary mechanism underlying the anti‐cancer activity of 3BP but the importance of targeting GAPDH for the cellular actions of arsenicals remains uncertain. We have studied the effects of 3BP and the representative trivalent arsenical phenylarsine oxide (PAO) on the growth, viability, metabolism, and GAPDH activity of the yeast Saccharomyces cerevisiae, which reproduces metabolic features of Warburg‐positive tumor cells. Both 3BP and PAO abolished growth and, within hours, caused substantial cell death measured by propidium uptake and fluorescence. Neither compound increased ROS levels nor inhibited protein synthesis. Indeed, lower concentrations of PAO appeared to decrease cellular ROS. Critically, exposure of intact cells to 3BP produced a rapid and nearly complete inhibition of GAPDH activity. In contrast, PAO did not inhibit the cellular activity of GAPDH despite findings, also to be presented, that GAPDH was one of many proteins from yeast lysates able to bind immobilized PAO. These results suggest that changes in the activity of GAPDH, in situ, may differentiate the cytotoxic pathways of cancer‐active electrophiles. The mechanism(s) underlying the impairment of growth and viability of S. cerevisiae by arsenicals remains under investigation.Support or Funding InformationFunding was provided by the University of ScrantonThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.