Design, synthesis, and characterisation of BLM and Pif1 helicase inhibitors

Design, synthèse et caractérisation d'inhibiteurs d'hélicase Pif1 et BLM Cancer is still a major cause of death worldwide. Among current cancer treatments, chemotherapy refers to the use of drugs to kill the malignant tumour. Conventional chemotherapeutic drugs target the cell cycle by causing non-specific DNA damage. Precision oncology is an emerging field of study, in which genetic tumour backgrounds are exploited for the benefit of targeted cancer therapy. The overexpression of DNA repair enzymes is an often-encountered mechanism for resistance to cancer treatment and the inhibition of DNA repair by small-molecule inhibitors can improve the outcomes of cancer treatment. The cellular DNA-damage response (DDR) is a series of intertwined pathways that detect DNA damages, signals their presence and executes their repair. Many proteins are involved in the repair of DNA, notably DNA topoisomerase and poly (ADP-ribose)polymerase (PARP) that have been largely investigated.Helicases are a class of enzymes involved in all major DNA repair pathways and are critical for genome stability. Inhibition of helicases is a promising approach for targeted therapy. Helicases are ubiquitous enzymes, acting as motor proteins to separate or remodel DNA or RNA duplexes. Given their essential tasks in living organisms, they are emerging as an important class of targets for antiviral, antibiotic and anticancer drugs. Despite the importance of helicases in cancer, little information on their exact involvement in DNA damage response pathways is known and only a few inhibitors have been described. The primary aim of this project was to design, synthesize and evaluate potential new inhibitors for two selected helicases, i.e., BLM and Pif1.Different strategies have been followed, including computer-aided drug design, to identify hits on these two helicase targets. Two structure-based virtual screenings, one for BLM and one for Pif1, were performed on allosteric binding pockets. Although our strategy failed to deliver hits on BLM helicase, our work has led to design and production of an innovative library that has been integrated in corporate collection of Edelris and constitutes a real asset for the company . Our approach was more successful on Pif1 helicase, leading to the identification of unprecedented micromolar inhibitors in a functional DNA unwinding assay. A covalent inhibitor featuring a reactive warhead introduced by rational design showed complete inhibition of the helicase. Protein-ligand co-crystallization and evaluation on several cancer cell lines of our compounds will still be performed in collaboration with academic partners from the AntiHelix program.