Small Molecules Targeting the RNA-Binding Protein HuR Inhibit Tumor Growth in Xenografts

Abstract

The RNA-binding protein Hu antigen R (HuR) is a post-transcriptional regulator critical in several types of diseases, including cancer, making it a promising therapeutic target. We have identified small-molecule inhibitors of HuR through a screening approach used in combination with fragment analysis. A total of 36 new compounds originating from fragment linking or structural optimization were studied to establish structure-activity relationships in the set. Two top inhibitors, <b>1c</b> and <b>7c</b>, were further validated by binding assays and cellular functional assays. Both block HuR function by directly binding to the RNA-binding pocket, inhibit cancer cell growth dependence of HuR, and suppress cancer cell invasion. Intraperitoneal administration of inhibitor <b>1c</b> inhibits tumor growth as a single agent and shows a synergistic effect in combination with chemotherapy docetaxel in breast cancer xenograft models. Mechanistically, <b>1c</b> interferes with the HuR-TGFB/THBS1 axis.