Untersuchung der antiviralen Wirkung des Naturstoffs Silvestrol – Etablierung der Helikase eIF4A als neue antivirale Zielstruktur

Cancer and viral infections are two of the most significant challenges in modern medicine. Each of them causes a vast amount of victims day by day and therefore needs intensive scientific efforts to find new strategies in their therapy. While searching for new approaches of already known drugs, we not only discovered a new antiviral substance, we more importantly found a new target for a new class of future antivirals. At the beginning of our studies, we analyzed the effect of statins on the proto-oncogene Pim-1. Statins are a well known and widely used class of drugs, utilized to lower the concentration of cholesterol in the blood. The treatment of cancer cells with simvastatin ends in the expected apoptotic effect. We show a putative mechanism, proven by qRT-PCR data in the cancer cell line HepG2. But the effect is massively dependent on the used cell line. While searching for other compounds in the literature, we become aware of silvestrol, an inhibitor of Pim-1. The target of silvestrol is the human helicase eIF4A, essential for the cap-dependent translation of highly structured 5'-UTRs. Soon it was obvious that this target is not only important in an oncogenic, but also in a viral context. Following this conclusion, this thesis will cover widely toxicological tests and studies of the antiviral effect of silvestrol against the HI-virus, the Ebola virus, and an overall broadspectrum antiviral activity. The tests of cell viability, cytotoxicity, and induction of apoptosis are performed in cancer cell lines as well as in primary human cells and show a tolerable toxicological profile. By using a customized dual-luciferase-assay (DLA), we can start investigating the mechanism of action and show a broad-spectrum activity. The DLA results and the transferability to truly infected cells are proven in multiple cell culture experiments, performed by cooperating labs. To make the benefit of this new target more accessible, we present an "advanced DLA". This assay offers the ability to test a huge amount of substances efficiently on their potency to selectively inhibit eIF4A.