development-inhibitors-protein-protein-interactions-through-replace

Development of Inhibitors of Protein-protein Interactions through REPLACE: Application to the Design and Development Non-ATP Competitive CDK Inhibitors

REPLACE is a unique strategy developed to more effectively target protein-protein interactions (PPIs). It aims to expand available drug target space by ...

University of South Carolina

Lon and ClpXP are the only soluble ATP-dependent proteases within the mammalian mitochondria matrix, which function in protein quality control by selectively degrading misfolded, misassembled, or damaged proteins. Chemical tools to study these proteases in biological samples have not been identified, thereby hindering a clear understanding of their respective functions in normal and disease states. In this study, we applied a proteolytic site-directed approach to identify a peptide reporter substrate and a peptide inhibitor that are selective for Lon but not ClpXP. These chemical tools permit quantitative measurements that distinguish Lon-mediated proteolysis from that of ClpXP in biochemical assays with purified proteases, as well as in intact mitochondria and mitochondrial lysates. This chemical biology approach provides needed tools to further our understanding of mitochondrial ATP-dependent proteolysis and contributes to the future development of diagnostic and pharmacological agents for treating diseases associated with defects in mitochondrial protein quality.

Active-site-directed chemical tools for profiling mitochondrial Lon protease.

Carbohydrates in various forms play a vital role in numerous critical biological processes. The detection of such saccharides can give insight into the progression of such diseases such as cancer. Boronic acids react with 1,2 and 1,3 diols of saccharides in non-aqueous or basic aqueous media. Herein, we describe the design, synthesis and evaluation of three bisboronic acid fluorescent probes, each having about ten linear steps in its synthesis. Among these compounds that were evaluated, 9b was shown to selectively label HepG2, liver carcinoma cell line within a concentration range of 0.5-10 μM in comparison to COS-7, a normal fibroblast cell line.

Synthesis and evaluation of aryl boronic acids as fluorescent artificial receptors for biological carbohydrates.

This report describes the design and application of several distinct gold-containing indoles as anticancer agents. When used individually, all gold-bearing compounds display cytostatic effects against leukemia and adherent cancer cell lines. However, two gold-bearing indoles show unique behavior by increasing the cytotoxic effects of clinically relevant levels of ionizing radiation. Quantifying the amount of DNA damage demonstrates that each gold-indole enhances apoptosis by inhibiting DNA repair. Both Au(I)-indoles were tested for inhibitory effects against various cellular targets including thioredoxin reductase, a known target of several gold compounds, and various ATP-dependent kinases. While neither compound significantly inhibits the activity of thioreoxin reductase, both showed inhibitory effects against several kinases associated with cancer initiation and progression. The inhibition of these kinases provides a possible mechanism for the ability of these Au(I)-indoles to potentiate the cytotoxic effects of ionizing radiation. Clinical applications of combining Au(I)-indoles with ionizing radiation are discussed as a new strategy to achieve chemosensitization of cancer cells.

Gold-containing indoles as anticancer agents that potentiate the cytotoxic effects of ionizing radiation.

Polo-like kinase (PLK)1 is the most studied of the PLK family and is a serine/threonine kinase that plays pivotal roles in many aspects of mitosis and hence its deregulation is prevalent in various malignant tumor types.

Current assessment of polo-like kinases as anti-tumor drug targets.

The cyclin groove is an important recognition site for substrates of the cell cycle cyclin dependent kinases and provides an opportunity for highly selective inhibition of kinase activity through a non-ATP competitive mechanism. The key peptide residues of the cyclin binding motif have been studied in order to precisely define the structure-activity relationship for CDK kinase inhibition. Through this information, new insights into the interactions of peptide CDK inhibitors with key subsites of the cyclin binding groove provide for the replacement of binding determinants with more druglike functionality through REPLACE, a strategy for the iterative conversion of peptidic blockers of protein-protein interactions into pharmaceutically relevant compounds. As a result, REPLACE is further exemplified in combining optimized peptidic sequences with effective N-terminal capping groups to generate more stable compounds possessing antitumor activity consistent with on-target inhibition of cell cycle CDKs. The compounds described here represent prototypes for a next generation of kinase therapeutics with high efficacy and kinome selectivity, thus avoiding problems observed with first generation CDK inhibitors.

Article	Year
Active-site-directed chemical tools for profiling mitochondrial Lon protease. ACS chemical biology\| PubMed ID: 21520912	2011
Synthesis and evaluation of aryl boronic acids as fluorescent artificial receptors for biological carbohydrates. Bioorganic chemistry\| PubMed ID: 22177855	2012
Gold-containing indoles as anticancer agents that potentiate the cytotoxic effects of ionizing radiation. Journal of medicinal chemistry\| PubMed ID: 22289037	2012
Current assessment of polo-like kinases as anti-tumor drug targets. Expert opinion on drug discovery\| PubMed ID: 24819909	2014
Iterative conversion of cyclin binding groove peptides into druglike CDK inhibitors with antitumor activity. Journal of medicinal chemistry\| PubMed ID: 25454794	2015

Sandra Craig

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