Pharmacogenomics and Drug Development
The Pharmacogenomics and Drug Development (PDD) Group at the Faculty of Pharmacy has interests in how human gene variation influences drug action and safety. The principal focus is on human drug metabolising enzymes (cytochromes P450 in particular) and transporters that determine the concentrations of drugs in tissues and their duration of action. The group includes four academic staff: Prof Michael Murray, Professor Iqbal Ramzan, Dr Nenad Petrovic and Dr Romano Fois, who collaborate on projects that cover clinical aspects of human drug safety as well as laboratory-based projects of human gene regulation in cells. The group also includes five full-time postdoctoral scientists and other senior staff, as well as a number of postgraduate, honours and visiting students from overseas institutions. Several members of the group have close affiliations with other academic researchers in teaching hospitals and links with industry and government.
The PDD group occupies laboratories in the Faculty of Pharmacy on main campus and in the newly refurbished Medical Foundation Building. The studies of human drug biotransformation are undertaken on main campus because of close access to excellent analytical facilities, including the Thomas R. Watson Mass Spectrometry and NMR facility, high performance liquid chromatography and other instrumentation. The MFB laboratories house our facilities for cell and molecular biology, immunohistochemistry and microscopy and protein biochemistry.
Clinical Studies ("personalised medicine")
The group has a number of ongoing collaborations with academic clinicians and clinical researchers within teaching hospitals off-campus. Thus, we study the role of genes involved in drug elimination and drug transport (and their variant forms) in the context of emerging problems with therapy.
At present the emphasis is on anti-cancer agents and certain antipsychotic drugs because these are associated with significant toxicity issues. By understanding better how variant forms of human genes influence adverse events we may be able to tailor drug therapy and drug dosage regimen to the individual.
Staff members within the PDD group also offer pharmacoepidemiologic projects and expertise that enable the real impact of gene variants on drug safety to be assessed. Collaboration with government authorities is an important aspect underpinning these particular studies.
Studies at the Medical Foundation Building are evaluating how dietary factors, especially the omega-3 fatty acids and their biotransformation products, regulate important features of human disease such as cancer, cardiovascular disease and arthritis.
Using a series of modern approaches in cell and molecular biology, that have been developed in house, we are able to explore how cell growth and proliferation is modulated by polyunsaturated fatty acids. Included in such studies is the use of reporter gene systems in transfected cells, and specially engineered transgenic animals, that allow the important control regions in human genes that regulate expression to be identified.
Dietary and other strategies that modulate the expression of cytochrome P450 2J2, a human gene with interesting cytoprotective and proliferative effects, in disease are currently being developed and tested. The growth of new blood vessels (angiogenesis) is a critical feature of tumourigenesis and is also modulated by certain derivatives of different polyunsaturated fatty acids (see Figure below).
Effect of derivatives of polyunsaturated fatty acids on blood vessel precursor formation by human endothelial cells in vitro. (Click for larger image.)
This test for angiogenesis measures the ability of activated endothelial cells to migrate and form three-dimensional structures (tubes). A derivative of the (omega)-6 fatty acid arachidonic acid (AA) induce tube formation whereas certain derivatives of the (omega)-3 fatty acids eicosapentaneoic (EPA) and stearidonic (SDA) are inhibitory.
Other experimental studies are evaluating the role of transporter proteins such as P-glycoprotein in drug safety and the duration of drug action. The regulation of these important proteins in disease and inter-individual variation in regulation is also under investigation. As shown below, confocal microscopy is used in cells transfected with a transporter-receptor construct to follow anti-cancer drug accumulation in subcellular compartments.
Intracellular accumulation of daunorubicin in P-gp-Enhanced Green Fluorescent Protein (EGFP) transfected HeLa cells in the absence and presence of verapamil(a classic P-gp inhibitor). (a) Transfected HeLa cells that overexpress P-g-EGFP (Green) at the cell surface fail to accumulate the substrate (1μM) daunorubicin (red). (b) When P-gp EGFP transfected HeLa cells are preincubated with 25 M verapamil for 1 hr at 37°C , cells readily accumulate daunorubicin in the intracellular compartment, confirming that P-gp mediated drug efflux occurs at the level of the plasma membrane. [Images were acquired by confocal microscopy]. (c) Quantitative analysis of the intracellular fluorescence intensity of daunorubicin in the presence and absence of Verapamil (25μM). Figure taken from Fu, Bebawy, Kable and Roufogalis. Int. J.Cancer 109, 174-181, 2004.