NR2F2 and NR2F6 as targets for drug repurposing: an insight by means of computational analysis

Abstract

Within the framework of the PNRR project “HEAL ITALIA”, we focussed our interest on a small group of orphan nuclear receptors (ORFs), a small family of ligand-dependent transcriptional factors (15 members) controlling the expression of various target genes. In this context, we performed structural analyses aimed at identifying small organic molecules capable of interacting with the selected sub-group of ORFs. The ultimate goal of the study is to identify compounds available in public drug databases, which may be ready to be tested against target ORFs in view of rapid translational medicinal chemistry applications “from the bench to the bed”. Like all ORFS, NR2Fs constitute a sub-group of three receptors lacking endogenous ligands, i.e. NR2F1 (COUPTFI, EAR-3), NR2F2 (COUP-TFII, ARP-1) and NR2F6 (COUP-TFIII, EAR-2). Structurally, the two most important regions of NR2Fs are the DBD (DNA binding domain) and the LBD (ligand binding domain), which act independently from each other. The overall structures of DBDs and LBDs are very similar in the three NR2F family members. In contrast, the structures of the N-terminal and the C-terminal regions of ORFs are variable. Indeed, the C-terminal region is missing in some ORFs and the knowledge on its functional significance is limited. Because of their central role in cell growth, NR2Fs are promising candidates as novel therapeutic targets in the treatment of cancer1. In the present study, we conducted a computational analysis on the X-ray crystal structures of the human NR2F2 ligand binding domain (PDB ID: 3CJW) and the human NR2F6 ligand binding domain (PDB ID: 8C5L). The initial aim of these analyses was to identify potential hotspot binding sites and to predict their druggability. Subsequently, we used the identified binding sites to perform a virtual screening protocol, involving pharmacophore models and docking studies, on large libraries such as Drugbank, FDA and commercial libraries for drug repurposing. We identified a number of drug hits as possible ligands/inhibitors of the target ORFs. Currently, we are in the process of verifying the ability of these compounds to interact with and modulate the activity of NR2Fs with the use of suitable biological tests.