Identification of small-molecule inhibitors against the interaction of RNA-binding protein PSF and its target RNA for cancer treatment

Inhibition of PSF Activity Overcomes Resistance to Treatment in Cancers Harboring Mutant p53

Mutations in the TP53 tumor suppressor genes are prevalent in aggressive cancers. Pharmacologic reactivation of dysfunctional p53 due to mutations is a promising strategy for treating such cancers. Recently, a multifunctional proline- and glutamine-rich protein, polypyrimidine tract-binding protein-associated splicing factor (PSF), was identified as a key driver of aggressive cancers. PSF promotes the expression of numerous oncogenes by modulating epigenetic and splicing mechanisms. We previously screened a small-molecule library and discovered compound No. 10-3 as a potent PSF inhibitor. Here, we report the discovery of a No. 10-3 analog, 7,8-dimethoxy-4-(4-methoxy-phenyl)-chromen-2-one (C-30), as a potent PSF inhibitor. Compared with No. 10-3, C-30 treatment specifically suppressed the growth and induced apoptosis of mutant p53-bearing and therapy-resistant cancer cells. Interestingly, C-30 activated a set of p53-regulated genes in therapy-resistant cancer cells. A comprehensive analysis of PSF and p53-binding regions demonstrated a higher level of PSF-binding potential in mutant p53-expressing cancer cells around genomic regions identified as p53-binding peaks in p53 wild-type cancer cells. Treatment of mutant p53-expressing cancer cells with C-30 decreases PSF binding around these sites, leading to activated histone acetylation. We further demonstrated that C-30 impaired tumor growth and increased the expression of p53 target genes in vivo. These results suggested that C-30 produces tumor-suppressive effects similar to the functional reactivation of p53, providing a rationale for the inhibition of PSF activity as a promising therapy against treatment-resistant cancer.

RNA binding proteins (RBPs) on genetic stability and diseases

RNA-binding proteins (RBPs) are integral components of cellular machinery, playing crucial roles in the regulation of gene expression and maintaining genetic stability. Their interactions with RNA molecules govern critical processes such as mRNA splicing, stability, localization, and translation, which are essential for proper cellular function. These proteins interact with RNA molecules and other proteins to form ribonucleoprotein complexes (RNPs), hence controlling the fate of target RNAs. The interaction occurs via RNA recognition motif, the zinc finger domain, the KH domain and the double stranded RNA binding motif (all known as RNA-binding domains (RBDs). These domains are found within the coding sequences (intron and exon domains), 5' untranslated regions (5'UTR) and 3' untranslated regions (3'UTR). Dysregulation of RBPs can lead to genomic instability, contributing to various pathologies, including cancer neurodegenerative diseases, and metabolic disorders. This study comprehensively explores the multifaceted roles of RBPs in genetic stability, highlighting their involvement in maintaining genomic integrity through modulation of RNA processing and their implications in cellular signalling pathways. Furthermore, it discusses how aberrant RBP function can precipitate genetic instability and disease progression, emphasizing the therapeutic potential of targeting RBPs in restoring cellular homeostasis. Through an analysis of current literature, this study aims to delineate the critical role of RBPs in ensuring genetic stability and their promise as targets for innovative therapeutic strategies.

Peptide-Based Nanoparticles Suppress Hepatic Inflammation via Blockage of Human Antigen R

Human antigen R (HuR), which is a mRNA-binding protein that stabilizes and regulates mRNA translation, is found to have increased expression in inflammation, cancer and other diseases, making HuR to be a promising drug target. This study reports a peptide-based nanoparticle (NP) system exhibits potent anti-inflammatory activity to ameliorate acute liver injury via the ability of peptides to inhibit the mRNA binding site of HuR and block downstream signaling. Molecular modeling provided structural evidence indicating that the peptides interact with the RNA-binding site of HuR, mainly via hydrogen-bonding and hydrophobic interactions. These peptide-based NPs can act as nanocarriers to deliver peptides into cells to compete with the mRNA binding site of HuR, evidenced by the reduction of antibody recognition to the native protein and the exhibition of anti-inflammatory activity against activated macrophage cells, with no adverse effect in vitro and in vivo. In LPS/D-GalN-induced hepatic sepsis with high dosage of LPS/GalN, administration of the NPs significantly attenuated necrosis and HuR expression, resulting in the significant improvement of animal survival rate, suggesting their therapeutic potential for hepatic inflammation and a broad range of HuR-overexpressed diseases.

Role of RNA binding proteins of the Drosophila behavior and human splicing (DBHS) family in health and cancer

RNA-binding proteins (RBPs) play crucial roles in the functions and homoeostasis of various tissues by regulating multiple events of RNA processing including RNA splicing, intracellular RNA transport, and mRNA translation. The Drosophila behavior and human splicing (DBHS) family proteins including PSF/SFPQ, NONO, and PSPC1 are ubiquitously expressed RBPs that contribute to the physiology of several tissues. In mammals, DBHS proteins have been reported to contribute to neurological diseases and play crucial roles in cancers, such as prostate, breast, and liver cancers, by regulating cancer-specific gene expression. Notably, in recent years, multiple small molecules targeting DBHS family proteins have been developed for application as cancer therapeutics. This review provides a recent overview of the functions of DBHS family in physiology and pathophysiology, and discusses the application of DBHS family proteins as promising diagnostic and therapeutic targets for cancers.