| Abstract | The human protein Pontin, which belongs to the AAA+ family, is overexpressed in several cancers and its silencing in vitro leads to tumor cell growth arrest and apoptosis, making it a good target for cancer therapy. In particular, high levels of expression were found in hepatic tumors for which the therapeutic arsenal is rather limited. The 3D structure of Pontin had previously been resolved, revealing an hexameric assembly with one ADP molecule co-crystallized in each subunit. Using Vina, Drugscore and Xscore, structure-based virtual screening of 2,200 commercial molecules was conducted into the ATP binding site formed by a dimer of Pontin in order to prioritize the best candidates. Complementary to the in silico screening, a versatile and sensitive colorimetric assay was set up to measure the disruption of the ATPase activity of Pontin. This assay allowed the determination of inhibition curves for more than twenty top scoring compounds, resulting in the identification of four ligands presenting an inhibition constant in the micromolar concentration range. Three of them inhibited tumor cell proliferation. The association of virtual screening and experimental assay thus proved successful for the discovery of the first small molecule inhibitors of Pontin. |
