title: Structure-dependent activation of NR4A2 (Nurr1) by 1,1-bis(3'-indolyl)-1-(aromatic)methane analogs in pancreatic cancer cells.
abstract: NR4A2 (Nurr1) is an orphan nuclear receptor with no known endogenous ligands and is highly expressed in many cancer cell lines including Panc1 and Panc28 pancreatic cancer cells. Structure-dependent activation of NR4A2 by a series of 1,1-bis(3'-indolyl)-1-(aromatic)methane (C-DIM) analogs was determined in pancreatic cancer cells transfected with yeast GAL4-Nurr1 chimeras and a UASx5-luc reporter gene or constructs containing response elements that bind NR4A2. Among 23 different structural analogs, phenyl groups containing p-substituted trifluoromethyl, t-butyl, cyano, bromo, iodo and trifluoromethoxy groups were the most active compounds in transactivation assay. The p-bromophenyl analog (DIM-C-pPhBr) was used as a model for structure-activity studies among a series of ortho-, meta- and para-bromophenyl isomers and the corresponding indole 2- and N-methyl analogs. Results show that NR4A2 activation was maximal with the p-bromophenyl analog and methylation of the indole NH group abrogated activity. Moreover, using GAL4-Nurr1 (full length) or GAL-Nurr1-A/B and GAL4-Nurr1-(C-F) chimeras expressing N- and C-terminal domains of Nurr1, respectively, DIM-C-pPhBr activated all three constructs and these responses were differentially affected by kinase inhibitors. DIM-C-pPhBr also modulated expression of several Nurr1-regulated genes in pancreatic cancer cells including vasoactive intestinal peptide (VIP), and the immunohistochemical and western blot analyses indicated that DIM-C-pPhBr activates nuclear NR4A2.
authors.affiliation: College of Medicine, Texas A&M Health Science Center, 1114 TAMU, College Station, TX 77843, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Syng-Ook
authors.initials: SO
authors.lastname: Lee
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D017931:DNA Primers; D006801:Humans; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology*; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2 / Q000737:chemistry / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000473:pathology*; D060888:Real-Time Polymerase Chain Reaction; D013329:Structure-Activity Relationship
chemical_list: D017931:DNA Primers; D007211:Indoles; C539882:NR4A2 protein, human; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2