Influence of human cytomegalovirus on tumor progression
Infection with human cytomegalovirus (HCMV) is very common in the population. Although the virus does not possess ability to transform normal cells (like classical tumor viruses), infection of already existing tumor cells with HCMV can increase the malignancy of the tumor (so called oncomodulation). Simultaneously, the efficacy of chemotherapeutic drugs is strongly decreased.
In our lab, we investigate the effects of HCMV infection and specific viral genes of HCMV on proliferation, cell cycle, apoptosis and angiogenesis of the tumor cells. It is possible that oncomodulatory effects are also excerted by viruses other than HCMV. Understanding the mechanisms that lead to oncomodulation is crucial for the development of new anti-tumor therapies, using combination of antiviral and antitumoral drugs.
We have developed cell culture models of respiratory viruses and herpes viruses which enable us to test different substances for their antiviral potency. This tool helped us to identify novel substances against e.g. Cytomegalovirus (desferol and sorafenib)
We also found effective substances against emerging highly pathogenic respiratory viruses like SARS-CoV (glycyrrhizin) or avian influenza H5N1 strains (natural substances like flavonoids or polyterpens).
Currently, a panel of 1443 US FDA (Food and Drug administration) approved drugs is tested for antiviral activity against HCMV and measles. For both viruses, we already identified some substances with antiviral activity.
Establishment and maintenance of a drug-resistant cancer cell line collection
Chemotherapy is often limited by development of chemoresistance in tumor cells (failure of therapy). A few commercial bioresource centers are already existing (e.g. NCI-60, JCFR-39, CMT1000), but these cell line collections do not contain chemoresistant tumor cells. For better understanding of the underlying mechanisms of chemoresistance and for the development of new therapy strategies, chemoresistant cancer cell in vitro -models are essential. Over the years, we have established a unique collection of resistant cancer cell lines (RCCL collection: http://www.kent.ac.uk/stms/cmp/RCCL/RCCLabout.html). The resistant cancer cell lines were gradually adapted over a longer perid of time to grow in the presence of one specific drug. Classical chemotherapeutic drugs were used in this adaptation process, as well as new compounds (targeted cancer therapeutics). Currently, the RCCL collection consists of more than 1,500 chemoresistant cancer cell lines with over 50 different drugs used for adaptation. Some of the resistant cancer cell lines are also established as xenografts in nude mouse model.
Apart from generating chemoresistant cell lines, we also have expertise in establishing cell lines out of biopsy material or primary probes, both of pediatric and adults patients.
Investigation of molecular chemoresistance mechanisms in tumor cells
Cell lines from the RCCL collection are used for studying the resistance mechanisms that led to failure of therapy. Some cell lines from the RCCL collection have already been used in an international project funded by the European Commission (EU-project “SYNLET”) and are currently used in a project sponsored by “Deutsche José Carreras Leukämie-Stiftung e.V.”. Cell lines from the RCCL collection are used by many collaborators all over the world and are therefore part of many publications in the field of cancer research.
In the context of chemoresistance mechanisms against nucleoside analogs, we discovered SAMHD1 as a novel resistance factor and possible biomarker in AML (acute myeloid leukaemia). The anti-cancer drug cytarabine provides the basis of chemotherapies directed against AML. In cytarabine-resistant AML cells from the RCCL collection, the toxicity of cytarabine correlates with the expression of the cellular enzyme SAMHD1, which enables to predict the sensitivity of AML cells to cytarabine. This was also shown in animal experiments as well as in samples from leukaemia patients. We could show that SAMHD1 removes the phosphate residues from the active form of cytarabine and thereby reverses it into its inactive state. In addition, the inhibition of SAMHD1 effectively sensitises cytarabine-resistant AML cells to cytarabine-based chemotherapies. This introduces SAMHD1 as clinical biomarker.
Live cell imaging can be performed on a bright field or fluorescence microscope. By using a high resolution camera, insight into cell functions due to viewing dynamic processes in living cells in real time is provided. The cells are cultivated in petri dishes, the microscope which is used for imaging the cell culture can be covered with a glass container. Inside this container a defined atmosphere can be created, so that cells can grow and proliferate in the petri dish over a longer period of time. A camera which is fixed to the microscope takes one picture at a defined time point (e.g. every sixty seconds). All pictures taken are ultimately assembled to one clip. By using this technique, temporal and spatial dynamics of vesicular trafficking, actin cytoskeleton, cell nucleus and secretory pathways in drug-treated or virus-infected cells can be imaged.<