Patrick Müller, Hannah Maus, Stefan Hammerschmidt
Due to its fast international spread and its substantial mortality, the coronavirus disease COVID-19 evolved to a global threat. Since currently there is no causative drug against this viral infection, science is striving for new drugs and approaches to treat the new disease. Studies have shown that the cell entry of coronaviruses into host cells takes place through binding of the viral spike (S) protein to cell receptors. Priming of the S protein occurs via hydrolysis by different host proteases (furin, cathepsin L, TMPRSS2 etc.). The inhibition of these proteases could impair the processing of the S protein, thereby affecting the interaction with the host-cell receptors and preventing virus cell entry. Hence, inhibition of these proteases could be a promising strategy for a treatment against SARS-CoV-2.
Figure 1: Schematic overview of the viral cell entry.
In cooperation with the research group of Prof. V. Mailänder we focus on the design of novel peptidomimetic TMPRSS2 inhibitors. Molecular modeling studies resulted in tripeptides that are synthesized and linked with an electrophilic serine trap (warhead) to create covalent inhibitors. The compounds are tested against the serine protease matriptase (surrogate enzyme) and other different enzymes to accomplish high affinity and selectivity. Stabilitiy assays are perfomed in blood serum, plasma and cell medium to evaluate the pharmacokinetic properties. Additionally, the antiviral effect of the most promising inhibitors are tested in CaCo-2 cells, which serve as a model for the human intestinal tract.
Figure 2: Development of peptidomimetic inhibtors. A: Computational modeling of potential binders. B: Synthesis of the covalent inhibitors. C: Validation of inhibitory effect of the synthesized compounds by bio-assays, e.g. fluorimetric AMC-assay.
Urokinase-type plasminogen activator (uPA)
Cancer continues to be one of the leading causes of death worldwide, according to the World Health Organization (WHO. Aggravated by the fact, that many cancer diseases like pancreatic and breast cancer involve complex metastatic behaviour, it presents a great challenge for the scientific community to develop promising strategies to cure cancer.
Studies in understanding the molecular biology in tumor growth and metastasis showed the important role of proteases in cancer. The upregulation of the urokinase-type plasminogen activator (uPA) plays a key role in the tumor progression and metastasis. The uPA-receptor regulates the system by localising the uPA on the cell surface. The enzyme activates the proteolytic-cascade wherby plasmin and other different matrix metalloproteases (MMPs) result in the uncontrolled remodelling of the surrounded environment, thus enabling the migration of tumor cells and formation of metastases. To date, no therapy adressing the uPA system (uPAS) to prevent cancer metastasis are approved.
Due to the lack of selective uPA inhibitors in the literature and its important role in cancer progression, our group focuses on the design and in vitro testing of potent peptidomimetic uPA inhibitors with an electrophilic serine trap to obtain compounds with beneficiary selectivity and activity parameters.
Figure 3: Schematic overview of metastasis involving the uPA.