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The cardiovascular field is still searching for a treatment for abdominal aortic aneurysms (AAA). This inflammatory disease is a deadly, permanent ballooning of the aortic artery. It often goes undiagnosed until a late stage where associated rupture has a high mortality rate. Surgery is the only option available to patients, but it is risky. There are currently no FDA-approved pharmacological treatments for AAA available. Historically, drugs that have been examined in interventional clinical trials for treatment of AAA were repurposed therapeutics. Novel treatments have been unable to reach the clinic, stalling out in pre-clinical studies. Exceedingly few murine studies have examined an intervention-based drug treatment in halting further growth of an established AAA despite interventional treatment being the therapeutic approach taken to treat AAA in a clinical setting. Overall, current research stresses the importance of both centralized antiinflammatory drug targets and rigor of translatability. Notably, microsomal prostaglandin E2 synthase-1 (mPGES-1) is recognized as a promising target for development of a next generation of anti-inflammatory drugs. To this end, it is suggested that inhibiting PGE2 formation with an mPGES-1 inhibitor is a leading drug target for AAA treatment. The Zhan Lab previously identified mPGES-1 inhibitors as potential anti-inflammatory drug candidates through two methods: structure-based rational design of novel small molecules and repurposing of FDA-approved drugs through computational modeling. The purpose of this work was to assess the capability of these lead mPGES-1 inhibitors to alter growth of AAA in the angiotensin (Ang)II-induced mouse model. We have shown successful implementation of a prevention-based treatment and more importantly, late-stage interventional drug treatment to modulate growth of AAA in this model. Additional studies supported the structure-activity relationship profile of our compounds and their potential translation into the clinical setting. Our results provide evidence supporting the use of mPGES-1 inhibitors as interventional treatment of AAA.

Ever since the advent of computer-aided drug design (CADD), in silico simulation methods have greatly accelerated the drug discovery process and lead to the discovery of numerous drug candidates. With the exponential growth of computational power, we nowadays simulate biologic systems at a scale unimaginable a decade ago and thus provides perspectives for drug design. In this dissertation research, combining in silico simulation methods like molecular docking and molecular dynamics (MD) simulation with organic synthesis, in vitro/in vivo experiments and clinical data mining, we developed new drug discovery strategies. These strategies were applied in our drug discovery projects and led to the discovery of inhibitors of microsomal prostaglandin E2 synthase 1 (mPGES-1) and butyrylcholinesterase (BChE) as potential drug candidates. Protein mPGES-1 is known as an ideal target for next generation of anti-inflammatory drugs without the side-effects of currently available anti-inflammatory drugs. Unfortunately, almost all the previously reported human mPGES-1 inhibitors are inactive (or possess very low activity) against mouse or rat mPGES-1 that prevents using well-established mouse/rat models of inflammation, pain, and other diseases for preclinical studies. It would be extremely challenging for the mPGES-1-based drug development to follow traditional drug discovery and development route. In order to solve this problem, we developed and applied Drug Repurposing Effort Applying Integrated Modeling-in vitro/vivo-Clinical Data Mining (DREAM-in-CDM) strategy in this project. With molecular dynamics simulation, we observed the process of how mPGES-1 adopts an alternative conformation to control the access of co-factor GSH (glutathione) and its impact on the function of the protein. Based on the simulation results, we not only found an explanation for the difference between the X-ray and CryoEM (cryogenic electron microscopy) structure of mPGES-1 but also used molecular docking method to identify FDA approved drug, lapatinib, as an mPGES-1 inhibitor by virtual screening and the subsequent in vitro experiments. By mining the available clinical trial data, we found solid evidence that lapatinib can be used to relieve various types of pain in cancer patients. Since lapatinib is very well tolerated, we expect lapatinib to be repurposed as a new treatment for cancer-related pain. BChE has been identified as an ideal drug target for the treatment of Alzheimer’s disease (AD) and heroin overdose. The selectivity of a therapeutically useful inhibitor for BChE over AChE is very important. Unfortunately, there is no good selective BChE inhibitor. With a robust and virtual screening strategy combining with in vitro experiments, we identified a series of compounds from the NCI compound depository as BChE inhibitors with novel scaffolds, high activity and selectivity at the same time. The most potent compound was re-synthesized and the enantiomers of the compound were separated for the first time. The binding mode of the most potent compound was also analyzed and the origin of its high activity and selectivity was revealed that will guide the development of BChE selective inhibitors in the future. In addition, a new tacrine-based BChE affinity chromatography resin was developed. The developed new resin has enabled us to more conveniently and efficiently purify the BChE proteins with improved high purity. In general, we have successfully developed new drug discovery strategies to identify novel inhibitors of different enzymes. With these newly developed strategies, we expect additional drug discoveries to be made in the foreseeable future.

Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) are currently widely used as fever and pain relief in patients with arthritis and other inflammatory symptoms. NSAIDs effect by inhibiting cyclooxygenase-1 (COX-1) and/or cyclooxygenase-2 (COX-2). COX isozymes (COXs) are key enzymes in the biosynthesis of prostaglandin H2 (PGH2) from arachidonic acid (AA). It is now clear that prostaglandin E2 (PGE2), one of the downstream products of PGH2, is the main mediator in both chronic and acute inflammation. Microsomal prostaglandin E synthase (mPGES-1) is the terminal enzyme of COX-2 in the PGE2 biosynthesis pathway. Different from other two constitutively expressed PGE2 synthase (PGES), mPGES-2 and cPGES, mPGES-1 is induced by pro-inflammatory stimuli and responsible for the production of PGE2 related to inflammation, fever and pain. For these reasons, selective inhibition of mPGES-1 is expected to suppress inflammation induced PGE2 production and, therefore, will exert anti-inflammatory activity while avoid the side effects of COXs inhibitors, such as gastrointestinal (GI) toxicity, and cardiovascular events. A combination of computational and experimental approaches was used to discovery mPGES-1 inhibitors with new scaffolds. The methods used include molecular docking, molecular dynamic simulation, molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) binding free energy calculation, and in vitro activity assays. Our large-scale structure-based virtual screening was performed on compounds in the NCI libraries, containing a total of ~260,000 compounds. 7 compounds have been determined for their IC50 values (about 300 nM to 8000 nM). What’s more, these new inhibitors of mPGES-1 identified from virtual screening did not shown significant inhibition against COX isozymes even at substantially high concentrations (e.g. 100 µM). Rational methodology for drug design and organic synthesis were applied to generate three series of mPGES-1 inhibitors with different scaffolds. In total, about 200 compounds were synthesized and tested for their in vitro inhibition against human mPGES-1. Compounds with high potency against human mPGES-1 were further screened for their inhibition against mouse mPGES-1 and selectivity of human mPGES-1 over COXs. Several compounds were identified as submicromolar inhibitors against human mPGES-1 with high selectivity over COXs. In general, we have successfully identified a library of compounds as potent mPGES-1 inhibitors without significant inhibition against COXs. Structure information and in vitro activity evaluation data generated from the virtual screening and the library of compounds will be used to guide future design and synthesis of the mPGES-1 inhibitors.