title: Reporter protein complementation imaging assay to screen and study Nrf2 activators in cells and living animals.
abstract: NF-E2-related factor-2 (Nrf2) activators promote cellular defense mechanism and facilitate disease prevention associated with oxidative stress. In the present study, Nrf2 activators were identified using cell-based luciferase enzyme fragment complementation (EFC) assay, and the mechanism of Nrf2 activation was studied by molecular imaging. Among the various Nrf2 activators tested, pterostilbene (PTS) showed effective Nrf2 activation, as seen by luminometric screening, and validation in a high throughput-intact cell-imaging platform. Further, PTS increased the expression of Nrf2 downstream target genes, which was confirmed using luciferase reporter driven by ARE-NQO1 and ARE-GST1 promoters. Daily administration of PTS disturbed Nrf2/Keap1 interaction and reduced complemented luciferase signals in HEK293TNKS mouse tumor xenografts. This study reveals the potentials of Nrf2 activators as chemosensitizing agents' for therapeutic intervention in cancer treatment. Hence, the validated assay can be used to evaluate the identified activators preclinically in small animal models by noninvasive molecular imaging approach.
authors.affiliation: SRM Research Institute, SRM University, Kattankulathur-603203, Tamilnadu, India.
authors.forename: Kunka Mohanram
authors.initials: KM
authors.lastname: Ramkumar
authors.forename: Thillai Veerapazham
authors.initials: TV
authors.lastname: Sekar
authors.forename: Kira
authors.initials: K
authors.lastname: Foygel
authors.forename: Bhakkiyalakshmi
authors.initials: B
authors.lastname: Elango
authors.forename: Ramasamy
authors.initials: R
authors.lastname: Paulmurugan
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D057809:HEK293 Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D051379:Mice; D057054:Molecular Imaging; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D013267:Stilbenes / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; D013267:Stilbenes; C107773:pterostilbene