Dr Karen Swales
Lecturer in Toxicology
Qualifications: PhD
Email: k.swales@surrey.ac.uk
Phone: Work: 01483 68 6390
Room no: 25 AY 04
Further information
Biography
I gained a BSc (Hons) Biochemistry (Toxicology) and a PhD in Molecular Toxicology under the supervision of Dr Nick Plant and Prof. Gordon Gibson, from the University of Surrey, where I became interested in orphan nuclear receptors. To further this interest, I moved to North Carolina, USA to be a visiting post-doctoral fellow in the laboratory of Dr Masahiko Negishi at the National Institute of Environmental Health Sciences, researching a novel mechanism of gene regulation by the nuclear receptor CAR. I then returned to the UK, to work with Dr David Bishop-Bailey, as a post-doctoral researcher investigating the role of the nuclear receptor FXR in cardiovascular disease. I obtained a 2 year independent fellowship from Barts and the London Charitable Trust to further my research into FXR in 2007. I returned to the University of Surrey as Lecturer in Toxicology in September 2008.
I was awarded the British Toxicology Society Early Career Investigator Prize in March 2011 for my research investigating nuclear receptors and their role in toxicity. The main receptors I currently study (PXR, FXR and CAR) make up a network that in response to potentially toxic compounds, including drugs and bile acids, regulate gene expression and thus protect the body from toxicity. I am now investigating whether this network can also protect against common diseases in humans, such as cardiovascular disease and cancer.
Research Interests
My current research focuses on the nuclear receptors, pregnane X receptor (PXR), farnesoid X receptor (FXR) and constitutive androstane receptor (CAR). These receptors make up a network that in response to chemical insults, such as drugs and bile acids, regulate gene expression and thus protect the body from toxicity. Given the impact of lifestyle and environment on key human diseases, such as breast cancer and cardiovascular disease, my work at Surrey is focussed on determining whether the changes in gene regulation mediated by the aforementioned nuclear receptors can be harnessed to protect against the development of these diseases.
Breast Cancer:
Breast cancer accounts for around 17% of female deaths from cancer in the UK, it is essential that new therapies are developed, diagnostic markers identified and the disease process understood. One potential novel therapeutic target is the nuclear receptor FXR. FXR is activated by bile acids, which have been shown to be present in some breast cancers and in breast cyst fluid. I have shown that FXR is expressed in human breast cancer, as well as being present and pro-apoptotic in human breast cancer cell lines. I also found that FXR down-regulates the enzyme aromatase, responsible for local pro-proliferative estrogen production, in human breast cancer cell lines. As breast cancer prognosis is dependent, not only, on the growth of the tumour but on its aggressiveness and metastasis to other organs, I am now investigating FXR as a novel therapeutic target for later stage breast cancer.
Cardiovascular Disease:
The vasculature is exposed to circulating endogenous, dietary and foreign chemicals. These chemical insults can contribute to the development of endothelial dysfunction, the initiating event in atherosclerosis. My previous work showed in vascular smooth muscle cells that FXR is anti-inflammatory and anti-migratory and therefore potentially anti-atherosclerotic. I have now shown that PXR can sense chemical insults and up-regulates drug metabolism and transport to protect against toxicity in the vasculature similar to its role in the liver and that it additionally protects against vascular oxidative stress.
Research Collaborations
National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle Park, North Carolina, USA
Dr Sanjeev Kumar
William Harvey Research Institute, Barts and the London - Queen Mary's School of Medicine and Dentistry, London
University of Surrey
Publications
See my new Cardiovascular Research publication here on PXR- novel protective gatekeeper of the vasculature
Highlights
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(2011) 'Pregnane X Receptor regulates drug metabolism and transport in the vasculature and protects from oxidative stress.'. Oxford University Press Cardiovascular Research, 93 (4), pp. 674-681.doi: 10.1093/cvr/cvr330Full text is available at: http://epubs.surrey.ac.uk/205733/
Abstract
Aims Circulating endogenous, dietary and foreign chemicals can contribute to vascular dysfunction. The mechanism by which the vasculature protects itself from these chemicals is unknown. This study investigates whether the pregnane X receptor (PXR), the major transcriptional regulator of hepatic drug metabolism and transport that responds to such xenobiotics, mediates vascular protection by co-ordinating a defence gene program in the vasculature.Methods and Results PXR was detected in primary human and rat aortic endothelial and smooth muscle cells and blood vessels including human and rat aorta. Metabolic PXR target genes cytochrome P450 3A, 2B, 2C and glutathione-S-transferase mRNA and activity were induced by PXR ligands in rodent and human vascular cells and absent in the aortas from PXR null mice stimulated in vivo or in rat aortic smooth muscle cells expressing dominant negative PXR. Activation of aortic PXR by classical agonists had several protective effects; increased xenobiotic metabolism demonstrated by bio-activation of the pro-drug clopidogrel, which reduced adenosine diphosphate-induced platelet aggregation; increased expression of multidrug resistance protein 1, mediating chemical efflux from the vasculature; and protection from reactive oxygen species-mediated cell death.Conclusions PXR co-ordinately up-regulates drug metabolism, transport and anti-oxidant genes to protect the vasculature from endogenous and exogenous insults, thus representing a novel gatekeeper for vascular defence.
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(2011) 'Endogenous epoxygenases are modulators of monocyte/macrophage activity.'. PLoS One, United States: 6 (10)Full text is available at: http://epubs.surrey.ac.uk/205725/
Abstract
Arachidonic acid is metabolized through three major metabolic pathways, the cyclooxygenase, lipoxygenase and CYP450 enzyme systems. Unlike cyclooxygenase and lipoxygenases, the role of CYP450 epoxygenases in monocyte/macrophage-mediated responses is not known.
- . (2007) 'Farnesoid X receptor ligands inhibit vascular smooth muscle cell inflammation and migration'. LIPPINCOTT WILLIAMS & WILKINS ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY, 27 (12), pp. 2606-2611.
- . (2006) 'The farnesoid X receptor is expressed in breast cancer and regulates apoptosis and aromatase expression'. AMER ASSOC CANCER RESEARCH CANCER RESEARCH, 66 (20), pp. 10120-10126.
Journal articles
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(2011) 'Pregnane X Receptor regulates drug metabolism and transport in the vasculature and protects from oxidative stress.'. Oxford University Press Cardiovascular Research, 93 (4), pp. 674-681.doi: 10.1093/cvr/cvr330Full text is available at: http://epubs.surrey.ac.uk/205733/
Abstract
Aims Circulating endogenous, dietary and foreign chemicals can contribute to vascular dysfunction. The mechanism by which the vasculature protects itself from these chemicals is unknown. This study investigates whether the pregnane X receptor (PXR), the major transcriptional regulator of hepatic drug metabolism and transport that responds to such xenobiotics, mediates vascular protection by co-ordinating a defence gene program in the vasculature.Methods and Results PXR was detected in primary human and rat aortic endothelial and smooth muscle cells and blood vessels including human and rat aorta. Metabolic PXR target genes cytochrome P450 3A, 2B, 2C and glutathione-S-transferase mRNA and activity were induced by PXR ligands in rodent and human vascular cells and absent in the aortas from PXR null mice stimulated in vivo or in rat aortic smooth muscle cells expressing dominant negative PXR. Activation of aortic PXR by classical agonists had several protective effects; increased xenobiotic metabolism demonstrated by bio-activation of the pro-drug clopidogrel, which reduced adenosine diphosphate-induced platelet aggregation; increased expression of multidrug resistance protein 1, mediating chemical efflux from the vasculature; and protection from reactive oxygen species-mediated cell death.Conclusions PXR co-ordinately up-regulates drug metabolism, transport and anti-oxidant genes to protect the vasculature from endogenous and exogenous insults, thus representing a novel gatekeeper for vascular defence.
- .
(2011) 'Endogenous epoxygenases are modulators of monocyte/macrophage activity.'. PLoS One, United States: 6 (10)Full text is available at: http://epubs.surrey.ac.uk/205725/
Abstract
Arachidonic acid is metabolized through three major metabolic pathways, the cyclooxygenase, lipoxygenase and CYP450 enzyme systems. Unlike cyclooxygenase and lipoxygenases, the role of CYP450 epoxygenases in monocyte/macrophage-mediated responses is not known.
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(2008) 'The Role of PPARs in the Endothelium: Implications for Cancer Therapy'. HINDAWI PUBLISHING CORPORATION PPAR RESEARCH, Article number ARTN 904251 doi: 10.1155/2008/904251Full text is available at: http://epubs.surrey.ac.uk/205732/
- . (2007) 'Farnesoid X receptor ligands inhibit vascular smooth muscle cell inflammation and migration'. LIPPINCOTT WILLIAMS & WILKINS ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY, 27 (12), pp. 2606-2611.
- . (2007) 'Purinergic 2X(1) receptors mediate endothelial dependent vasodilation to ATP'. AMER SOC PHARMACOLOGY EXPERIMENTAL THERAPEUTICS MOLECULAR PHARMACOLOGY, 72 (5), pp. 1132-1136.
- . (2007) 'Nongenomic signaling of the retinoid X receptor through binding and inhibiting Gq in human platelets'. AMER SOC HEMATOLOGY BLOOD, 109 (9), pp. 3741-3744.
- . (2006) 'The farnesoid X receptor is expressed in breast cancer and regulates apoptosis and aromatase expression'. AMER ASSOC CANCER RESEARCH CANCER RESEARCH, 66 (20), pp. 10120-10126.
- . (2005) 'Novel CAR-mediated mechanism for synergistic activation of two distinct elements within the human cytochrome P450 2B6 gene in HepG2 cells.'. J Biol Chem, United States: 280 (5), pp. 3458-3466.
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(2004) 'CAR, driving into the future.'. Mol Endocrinol, United States: 18 (7), pp. 1589-1598.doi: 10.1210/me.2003-0397Full text is available at: http://epubs.surrey.ac.uk/205724/
Abstract
The nuclear orphan receptor CAR is active in the absence of ligand with the unique capability to be further regulated by activators. A number of these activators, including phenobarbital, do not directly bind to the receptor. Considered a xenobiotic sensing receptor, CAR transcriptionally modifies the expression of genes involved in the metabolism and elimination of xenobiotics and steroids in response to these compounds and other cellular metabolites. Its hepatic expression pattern endows the liver with the ability to protect against not only exogenous but also endogenous insults. The mechanism of CAR activation is complex, involving translocation from the cytoplasm to the nucleus in the presence of activators, followed by further activation steps in the nucleus. Although this mechanism remains under investigation, we have summarized here the cellular signaling pathways elucidated so far and speculate on the mechanism by which CAR activators regulate gene expression through this network.
- . (2003) 'Relative receptor expression is a determinant in xenobiotic-mediated CYP3A induction in rat and human cells.'. Xenobiotica, England: 33 (7), pp. 703-716.
- . (2002) 'Receptor-dependent transcriptional activation of cytochrome P4503A genes: induction mechanisms, species differences and interindividual variation in man'. TAYLOR & FRANCIS LTD XENOBIOTICA, 32 (3), pp. 165-206.
- . (2002) 'Topics in xenobiochemistry: Receptor-dependent transcriptional activation of cytochrome P4503A genes: Induction mechanisms, species differences and interindividual variation in man'. Xenobiotica, 32 (3), pp. 165-206.
- . (2001) 'Investigation of host cell effects on xenobiotic induction of CYP3A'. ELSEVIER SCI IRELAND LTD TOXICOLOGY, 168 (1), pp. 128-129.
- . (2000) 'Use of suppression-PCR subtractive hybridisation to identify genes that demonstrate altered expression in male rat and guinea pig livers following exposure to Wy-14,643, a peroxisome proliferator and non-genotoxic hepatocarcinogen'. ELSEVIER SCI IRELAND LTD TOXICOLOGY, 144 (1-3), pp. 13-29.
Conference papers
- . (2004) 'Novel mechanism of CAR-mediated CYP2B6 induction'. TAYLOR & FRANCIS INC DRUG METABOLISM REVIEWS, Vancouver, CANADA: 7th European ISSX Meeting 36, pp. 313-313.
Teaching
Undergraduate
BMS1030 Biochemistry 1
BMS2036 Molecular Biology and Genetics 2 (Module organiser)
BMS3010 Mechanisms of Toxicity
Postgraduate
MSc (Toxicology)
TOXM001 Principles of Toxicology 1
TOXM002 Principles of Toxicology 2
TOXM003 Tissue Specific Toxicity 1 (Module Organiser)
TOXM004 Tissue Specific Toxicity 2
TOXM007 Techniques in Toxicology
MSc (Drug Discovery and Design)
CHEM017 Pharmacology and Toxicology
MSc (Applied Toxicology)
Target Organ Toxicology – Systems I: Liver, Kidney, GI Tract and Skin
Departmental Duties
FHMS Research Events Co-ordinator
Follow links for information on events within FHMS or the annual Festival of Research
Faculty Research and Enterprise Committee (FRC)
Chair of the FRC Faculty Research Support Fund (FRSF) Sub-committee
Module Organiser - TOXM003 Tissue Specific Toxicity 1
BMS2036 Molecular Biology and Genetics 2


