eIF2 kinases mediate β-lapachone toxicity in yeast and human cancer cells

Abstract

b-lapachone (b-lap) is a novel anticancer agent that selectively induces cell death in human cancer cells, by activation of the NQO1 NAD(P)H dehydrogenase and radical oxygen species (ROS) generation. We characterized the gene expression profile of budding yeast cells treated with b-lap using cDNA microarrays. Genes involved in tolerance to oxidative stress were differentially expressed in b-lap treated cells. b-lap treatment generated reactive oxygen species (ROS), which were efficiently blocked by dicoumarol, an inhibitor of NADH dehydrogenases. A yeast mutant in the mitocondrial NADH dehydrogenase Nde2p was found to be resistant to b-lap treatment, despite inducing ROS production in a WT manner. Most interestingly, DNA damage responses triggered by b-lap were abolished in the nde2D mutant. Amino acid biosynthesis genes were also induced in b-lap treated cells, suggesting that b-lap exposure somehow triggered the General Control of Nutrients (GCN) pathway. Accordingly, b-lap treatment increased phosphorylation of eIF2a subunit in a manner dependent on the Gcn2p kinase. eIF2a phosphorylation required Gcn1p, Gcn20p and Nde2p. Gcn2p was also required for cell survival upon exposure to b-lap and to elicit checkpoint responses. Remarkably, b-lap treatment increased phosphorylation of eIF2a in breast tumor cells, in a manner dependent on the Nde2p ortholog AIF, and the eIF2 kinase PERK. These findings uncover a new target pathway of b-lap in yeast and human cells and highlight a previously unknown functional connection between Nde2p, Gcn2p and DNA damage responses.

Anti-tubercular profile of new selenium-menadione conjugates against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain and multidrug-resistant clinical isolates

“…Naphthoquinones present a chemical structure of naphthalene with two ketone groups at position C-1 and C-2 (1,2-naphthoquinones) or C-1 and C-4 (1,4-naphthoquinones) [ 9 ]. The considerable interest in these compounds is based on their pharmacological activities, especially as antimicrobial [ [8] , [9] , [10] , [11] ] and antitumor agents [ [12] , [13] , [14] , [15] ]. Most recently, 1,4-naphthoquinones, such as menadione (vitamin K3), have aroused a lot of interest due to relevant anticancer activity [ 16 ].…”

β-Lapachone enhances the antifungal activity of fluconazole against a Pdr5p-mediated resistant Saccharomyces cerevisiae strain

“…Anaissi-Afonso et al [36] have also observed that βlap and derivatives at 10-100 μM exert their antifungal activity through oxidative stress and mitochondrial disfunction. On the other hand, Menacho-Márquez et al [37] observed that preincubation with dicoumarol did not affect the antifungal toxicity of β-lap, indicating that ROS production is not the mechanism responsible for the toxicity of β-lap against S. cerevisiae. In this study, it was observed that combining β-lap and fluconazole did not enhance ROS production.…”

Distinct responses of compartmentalized glutathione redox potentials to pharmacologic quinones targeting NQO1

“…The data indicated the mitochondrial electron transport chain, specifically respiratory complex I, to be a principal factor in redox activation of β-lap [10]. Although the main mechanism of cancer cell killing by β-lap is ROS-dependent, recent evidence suggested an alternative, ROS-independent, pathway for β-lap toxicity [11]. These results imply that chemotherapeutic quinones may react with multiple cellular constituents to promote cancer cell death, and the efficacy of NQO1-bioactivatable drugs may be improved by concomitant targeting of several cancer-specific metabolic pathways [6, 12].…”