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

Area of Science:

• Molecular Biology
• Biochemistry
• Cancer Research

Background:

• Beta-lapachone (β-lap) is an anticancer agent inducing cancer cell death via NQO1 activation and reactive oxygen species (ROS) generation.
• Understanding the molecular mechanisms of β-lap action is crucial for its therapeutic development.

Purpose of the Study:

• To characterize the gene expression profile of yeast cells treated with β-lap.
• To identify novel pathways and molecular targets of β-lap in both yeast and human cancer cells.

Main Methods:

• cDNA microarrays to analyze gene expression changes in β-lap treated yeast.
• Utilizing yeast mutants (nde2Δ) and specific inhibitors (dicoumarol) to dissect β-lap's mechanism of action.
• Investigating protein phosphorylation (eIF2α) and its dependence on specific kinases (Gcn2p, PERK) and proteins (Nde2p, AIF).

Main Results:

• β-lap treatment induced genes involved in oxidative stress tolerance and generated ROS, which were blocked by dicoumarol.
• A yeast mutant lacking mitochondrial NADH dehydrogenase (nde2Δ) showed resistance to β-lap and abolished DNA damage responses.
• β-lap treatment activated the General Control of Nutrients (GCN) pathway, increasing eIF2α phosphorylation in a manner dependent on Gcn1p, Gcn20p, and Nde2p.
• Nde2p ortholog AIF and eIF2 kinase PERK were involved in β-lap-induced eIF2α phosphorylation in breast tumor cells.

Conclusions:

• β-lap activates a novel pathway involving Nde2p, Gcn2p, and DNA damage responses in yeast.
• This pathway is conserved in human cells, with Nde2p ortholog AIF and PERK playing key roles.
• Findings highlight a previously unrecognized connection between mitochondrial NADH dehydrogenases, nutrient stress response, and DNA damage, offering new therapeutic targets for β-lap.