Commonly used inhibitors of the enzyme sarco/endoplasmic reticulum calcium-ATPase (SERCA) derived from the natural product thapsigargin (TG) suffer from limitations attributed to their high structural complexity, which restricts their availability and makes their customization by organic synthesis challenging and cumbersome. Because of their value as powerful research tools for the study of SERCA's role in physiological processes and their potential as novel agents against prostate cancer, the development of alternatives to TG-based SERCA inhibitors is highly desirable. The research outlined in this proposal is the design and the in-depth characterization of novel SERCA inhibitors based on the structure of hydroquinone (HQ). Despite their smaller size and lower complexity, HQ- based inhibitors - while readily available and conveniently customized - display remarkably high potencies against SERCA activity. As an important step towards the long-term goal of obtaining a comprehensive understanding of SERCA's interaction with small inhibitory molecules, the objective of this particular application is the discovery and comprehensive characterization of HQ-based inhibitors that are good candidates for the future development into research tools or anti-cancer agents. Preliminary data support the central hypothesis that the further development of HQs into a new SERCA inhibitor class is a feasible task and will likely yield novel research tools and/or anti-cancer agents. Inhibitors that are predicted to have good potencies will be synthesized or obtained by compound library screens and their potencies will then be measured in bioassays. The feasibility of attaching peptide tethers to SERCA inhibitors to convey specificity for prostate cancer cells will also be evaluated. Complementary to synthesis, library screens, and bioassays, a selection of the most potent compounds will be characterized thoroughly by molecular dynamics (MD) simulations in order to furnish a time-dependent account of the intermolecular interactions and events in the binding site at the molecular level. Supported by some crystallographic work, the MD simulations will also predict binding affinities of inhibitors for SERCA in order to help guide the synthesis of new compounds. Furthermore, the ability of SERCA inhibitors to interfere with the enzyme's Ca2+ transport function in living systems will be assessed in imaging studies with healthy and cancerous cells. The proposed research is innovative because it will explore the HQ scaffold as an attractive alternative to TG-based SERCA inhibitors. Moreover, its significance stems from its goal of generating fundamental information that is necessary to eventually develop HQs into valuable new research tools and into novel agents against prostate cancer. By engaging undergraduate research students in a multi-disciplinary drug design project, the planned project meets the goals of the NIH AREA program.
The objective of the proposed research is relevant to public health because it targets the development of a novel class of enzyme inhibitors that are valuable tools for biomedical research and promising candidates for the development of new drugs against prostate cancer. Compared to currently used compounds, these new inhibitors of the physiologically important enzyme sarco/endoplasmic reticulum calcium ATPase (SERCA) have the advantage of being structurally simple, readily available, and yet effective. In addition to advancing the field of SERCA inhibition by small molecules, this multi-disciplinary project meets the stated objectives of the AREA program by offering undergraduate students hands-on training in modern drug design methodologies and strengthening the research environment at Northern Kentucky University.
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