Uniform TitleConstruction of the 3D structure of the mTOR kinase-domain and discovery of novel mTOR inhibitors
NameTobak, Anne Theresa (author), Olson, Wilma (chair), Welsh, William (internal member), Ehrlich, Paul (internal member), Kong, Tony (outside member), Zheng, Steven (outside member), Rutgers University, Graduate School-New Brunswick,
SubjectComputational Biology and Molecular Biophysics,
DescriptionThe mammalian target of rapamycin (mTOR) is a serine/threonine kinase involved in the regulation of protein translation and cell proliferation. Based on signals received from nutrition, growth factors, and insulin, mTOR controls cell growth accordingly and is therefore a key target for anticancer therapeutics through its inhibition. Two regions of interest are the FRB domain, where mTOR's natural ligand rapamycin binds when in complex with FKBP12, and the ATP-binding site located within the kinase-domain. Because cancer cells have shown resistance to rapamycin's inhibitory effects, the kinase portion of the protein has become an attractive target for the design of novel inhibitors. Current kinase-domain inhibitors generally lack stability and specificity, mainly due to the absence of a high-resolution crystal structure for mTOR. Therefore, an urgent need exists for more insight into mTOR's three-dimensional (3D) structure as well as improved kinase-domain targeted therapeutics.
The purpose of this study was to construct a 3D structural model of the mTOR kinase-domain using homology modeling techniques, which would then facilitate the discovery of novel compounds with increased inhibitory effects. After constructing the mTOR structural model, we employed pharmaceutical drug design approaches to virtually 'dock' known mTOR kinase inhibitors into the putative ligand binding pocket of the kinase domain. Using the key structural features of mTOR inhibitors LY294002 and wortmannin, two pharmacophores were created and later employed as queries in our in silico search of commercially available compounds. This systematic procedure yielded 14 novel compounds, 7 from each pharmacophore search, which were purchased in sufficient quantities for initial biological evaluation. Western blot experimental results revealed that 4 of the 14 test compounds show mTOR inhibition in vitro at 10uM concentration.
Analysis of the lead compounds' binding interactions with mTOR identifies several active site residues potentially responsible for ligand binding affinity. In order for a small molecule to possess mTOR inhibitory activity, it it must establish interactions with Leu2186, Ile2237, and Ile2356. In addition, it must also make contact with Lys2166 and/or Val2240. Our homology model, in conjunction with these findings, will facilitate the continued rational (computer-aided) design of potent and selective mTOR kinase domain inhibitors.
Note[bibliography] Includes bibliographical references (p. 86-94).
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.