A transgenic macrophage-based platform to assess the efficacy and specificity of HuR modulators in inflammation

Abstract

RNA-binding proteins (RBPs) are essential controllers of RNA metabolism, and their deregulation can cause various pathologies. Human Antigen R (HuR) is an RBP engaged in the nuclear and cytoplasmic regulation of critical RNAs involved in cellular homeostasis. Conversely, its deregulation leads to tissue degeneration, cancer and immunopathology, fueling efforts for its exploitation as a target for relevant therapeutics. An expanding list of natural and synthetic compounds has been generated that disrupt HuR’s affinity for RNA, block its subcellular movements or debilitate its expression. The use of such HuR-inhibitors shows promise in the management of several cancers. However, the divergent functions of HuR on inflammatory degenerations – as revealed in animal models of HuR’s obligatory and tissue-specific ablation – raise skepticism on the use of HuRinhibitors against inflammatory reactions – including those associated with tumors. In many cases, this is due to the poor integration of appropriate cell-based assays to provide insights into applicability for controlling inflammatory reactions. Here, we present a transgenic macrophage-based platform for the functional assessment of HuR inhibitors that considers the context of HuR activities in inflammation that fail when HuR is lost. We employ this platform to assess the specificity and efficacy of three publicly available and prototypical HuR disruptors and two anti-inflammatory compounds known to alter HuR’s subcellular localization. We demonstrate that only one HuR-disruptor possesses HuR-dependent and selective anti-inflammatory activities, which do not extend the pathologic side effects incurred by the complete obliteration of HuR in immune cells. Our data provide a proof-of-principle case on appropriately assessing the modulators of HuR, highlighting the need to exploit context-specific cell-based assays for the preclinical evaluation of RBP inhibitors.

Keywords

• post-transcriptional regulation
• rna-binding proteins
• animal models
• au-rich elements
• chemotherapeutics
• cancer
• preclinical evaluation