Nuclear receptor 4A2 (NR4A2) is a druggable target for glioblastomas

• Published in: Journal of neuro-oncology 2020-01, Vol.146 (1), p.25-39
• Main Authors: Karki, Keshav, Li, Xi, Jin, Un-Ho, Mohankumar, Kumaravel, Zarei, Mahsa, Michelhaugh, Sharon K., Mittal, Sandeep, Tjalkens, Ronald, Safe, Stephen
• Format: Article
• Language: English
• Subjects: Animal models; Animals; Annexin V; Antagonists; Antineoplastic Agents - pharmacology; Antisense oligonucleotides; Apoptosis; Biomarkers, Tumor - genetics; Biomarkers, Tumor - metabolism; Boyden chamber; Brain cancer; Cell Movement; Cell Proliferation; Dopamine receptors; Female; Gene Expression Regulation, Neoplastic - drug effects; Gene silencing; Glioblastoma; Glioblastoma - drug therapy; Glioblastoma - metabolism; Glioblastoma - pathology; Humans; Indoles; Indoles - pharmacology; Inflammation; Laboratory Investigation; Medicine; Medicine & Public Health; Mice; Mice, Nude; Neurodegeneration; Neurology; Nuclear Receptor Subfamily 4, Group A, Member 2 - antagonists & inhibitors; Nuclear Receptor Subfamily 4, Group A, Member 2 - genetics; Nuclear Receptor Subfamily 4, Group A, Member 2 - metabolism; Oncology; Patients; Prognosis; RNA, Small Interfering - genetics; Survival Rate; Therapeutic applications; Tumor Cells, Cultured; Tumors; Western blotting; Xenograft Model Antitumor Assays; Xenografts
• ISSN: 0167-594X; 1573-7373
• DOI: 10.1007/s11060-019-03349-y

Introduction The orphan nuclear receptor 4A2 (NR4A2) has been extensively characterized in subcellular regions of the brain and is necessary for the function of dopaminergic neurons. The NR4A2 ligand, 1,1-bis (3 1 -indoly1)-1-(p-chlorophenyl)methane (DIM-C-pPhCl) inhibits markers of neuroinflammation and degeneration in mouse models and in this study we investigated expression and function of NR4A2 in glioblastoma (GBM). Methods Established and patient-derived cell lines were used as models and the expression and functions of NR4A2 were determined by western blots and NR4A2 gene silencing by antisense oligonucleotides respectively. Effects of NR4A2 knockdown and DIM-C-pPhCl on cell growth, induction of apoptosis (Annexin V Staining) and migration/invasion (Boyden chamber and spheroid invasion assay) and transactivation of NR4A2-regulated reporter genes were determined. Tumor growth was investigated in athymic nude mice bearing U87-MG cells as xenografts. Results NR4A2 knockdown and DIM-C-pPhCl inhibited GBM cell and tumor growth, induced apoptosis and inhibited migration and invasion of GBM cells. DIM-C-pPhCl and related analogs also inhibited NR4A2-regulated transactivation (luciferase activity) confirming that DIM-C-pPhCl acts as an NR4A2 antagonist and blocks NR4A2-dependent pro-oncogenic responses in GBM. Conclusion We demonstrate for the first time that NR4A2 is pro-oncogenic in GBM and thus a potential druggable target for patients with tumors expressing this receptor. Moreover, our bis-indole-derived NR4A2 antagonists represent a novel class of anti-cancer agents with potential future clinical applications for treating GBM. Graphic abstract