Comparison of Redox-Active and Conjugative Enzymes With and Without Efflux Transporters and Their Comparative Effectiveness in Protection Against Cellular Toxicity of 4-Hydroxy-2-Nonenal (HNE), an Aldehyde Lipid Peroxidation Production

4-hydroxy-2-nonenal (HNE) is one of the most reactive aldehydes produced during lipid peroxidation (LPO) and has been demonstrated to have cytotoxic and genotoxic effects. Several oxidoreductases (ORs) have been reported to detoxify HNE including aldehyde dehydrogenase (ALDH) and aldo-keto reductases (AKRs). Glutathione S-transferases (GSTs) are known to play a role in the detoxification of HNE by the formation of an HNE-glutathione (GSH) conjugate. We used stable transfection of V79 or MCF7 cell lines to generate transgenic model systems to compare protection across the different enzyme classes represented by ALDH3, GST 5.7, and AKR1C1. ALDH3 showed strong protection against HNE cytotoxicity, protein adduct formation, and GSH depletion. AKR1C1 and GST 5.7 failed to protect against these endpoints. The hemi-acetal ring of the HNE-SG conjugate can break to form an open chain aldehyde-SG, which can be cytotoxic by reacting with cellular macromolecules. Thus, efflux transporters including multi-drug resistance proteins (MRP1/MRP2) may be required for removal of HNE-SG. The combined role of GSTs with MRP1/2 was studied in stably transfected MCF7 and a HepG2 cell line model. Co-expression of GSTM1 + MRP1 leads to increased HNE-protein adducts formation and sensitization to HNE cytotoxicity (0.44 fold). Expression of GSTM1 alone and MRP1 alone leads to moderate but significant sensitization (0.7- 0.8 fold). GSH depletion was significant in MRP1 expressing cell lines (MCF7/MRP1 and MCF7/MRP1/GSTM1), with only 15-17 % GSH remaining after exposure of 60 μM HNE for 60 min. The mechanism by which GST and MRP1/2 modulate HNE cellular toxicity needs to be elucidated.

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2009

Author dc:creator

• Rudd, Lisa

• Redox-Active

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10339/14662

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/14662