Design, synthesis and biological evaluation of PDZ1 targeting NHERF1 inhibitors as anticancer agents

NHERF1 (Na+/H+ exchanger 3 regulating factor 1) is an integral membrane adaptor protein carrying two NH2-terminal PDZ (postsynaptic density 95/discs large/zona occludens 1) tandem domains. PDZ1 (11-97 amino acids) and PDZ2 (150-237 amino acids) show 74% identity to each other and bind to specific carboxyl-terminal motifs on target proteins, such as E-catenin and PTEN, that may have a pivotal role in tumorigenesis. Oncogenic activity of NHERF1 is strictly dictated by changes on its subcellular localization. A pharmacophore model was used to filter out an in-house training set of about 6000 compounds, leading to identify a potent inhibitor of NHERF1. We herein reported the design and synthesis of new NHERF1 inhibitors (Figure 1). The new compounds were synthesized by treating the appropriate indole with thionyl chloride and the proper amino derivative in the presence of pyridine in dichloromethane at room temperature for 12 h; alternatively, the coupling reaction was carried out using (benzotriazol-1- yloxy)tripyrrolidinophosphonium hexafluorophosphate and triethylamine in N,N-dimethylformamide at room temperature for 12 h. Compounds 5, 9, 10 and 13 exhibited a remarkable cytotoxicity in Ls174TshE-Cat cells. The binding to NHERF1 PDZ was confirmed by means of a dansylated peptide corresponding to the C-terminal sequence of E2-AR. When used in combination with antagonists of E-catenin, the new derivatives increased the apoptotic death of colorectal cancer cells refractory to currently available Wnt/E-catenintargeted agents.