title: Nuclear receptor 4A1 (NR4A1) as a drug target for treating rhabdomyosarcoma (RMS).
abstract: The orphan nuclear receptor NR4A1 is expressed in tumors from rhabdomyosarcoma (RMS) patients and Rh30 and RD RMS cell lines, and we used RNA interference (RNAi) to investigate the role of this receptor in RMS cells. Knockdown of NR4A1 in Rh30 cells decreased cell proliferation, induced Annexin V staining and induced polyADPribose polymerase (PARP) cleavage and these results were similar to those observed in other solid tumors. Previous studies show that NR4A1 regulates expression of growth promoting/pro-survival genes with GC-rich promoters, activates mTOR through suppression of p53, and maintains low oxidative stress by regulating expression of isocitrate dehydrogenase 1 (IDH1) and thioredoxin domain containing 5 (TXNDC5). Results of RNAi studies demonstrated that NR4A1 also regulates these pathways and associated genes in RMS cells and thereby exhibits pro-oncogenic activity. 1,1-Bis(3-indolyl)-1-(p-substituted phenyl)methane (C-DIM) analogs containing p-hydroxyl (DIM-C-pPhOH) and p-carboxymethyl (DIM-C-pPhCO2Me) substituents are NR4A1 ligands that decreased NR4A1-dependent transactivation in RMS cells and inhibited RMS cell and tumor growth and induced apoptosis. Moreover, the effects of NR4A1 knockdown and the C-DIM/NR4A1 antagonists were comparable as inhibitors of NR4A1-dependent genes/pathways. Both NR4A1 knockdown and treatment with DIM-C-pPhOH and DIM-C-pPhCO2Me also induced ROS which activated stress genes and induced sestrin 2 which activated AMPK and inhibited mTOR in the mutant p53 RMS cells. Since NR4A1 regulates several growth-promoting/pro-survival pathways in RMS, the C-DIM/NR4A1 antagonists represent a novel mechanism-based approach for treating this disease alone or in combination and thereby reducing the adverse effects of current cytotoxic therapies.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, 77843, TX, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Lacey
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, 77843, TX, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Hedrick
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, 77843, TX, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, 32307, FL, USA.
authors.forename: Ketan
authors.initials: K
authors.lastname: Patel
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, 32307, FL, USA.
authors.forename: Ravi
authors.initials: R
authors.lastname: Doddapaneni
authors.affiliation: College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, 32307, FL, USA.
authors.forename: Mandip
authors.initials: M
authors.lastname: Singh
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, 77843, TX, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Safe
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008819:Mice, Nude; D058990:Molecular Targeted Therapy / Q000379:methods*; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology*; D010648:Phenylacetates / Q000494:pharmacology*; D034622:RNA Interference; D012208:Rhabdomyosarcoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D047368:Tumor Burden / Q000187:drug effects / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: C552530:1,1-bis(3'-indolyl)-1-(4-hydroxyphenyl)methane; D007211:Indoles; C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D010636:Phenols; D010648:Phenylacetates; C000610380:p-carboxymethylphenyl 1,1-bis(3'-indolyl)-1-(p-carboxymethylphenyl)methane
keywords: C-DIMs; NR4A1; NR4A1 antagonists; inhibition; rhabdomyosarcoma