Susan P.C. Cole, PhD, FRSC, FCAHS
Office Phone: 613-533-2636
Lab: 613-533-6358; Fax: 613-533-6830
- Queen's University Bracken Chair in Genetics & Molecular Medicine
- Canada Research Chair in Cancer Biology (Tier 1)
- Fellow of the Royal Society of Canada and Canadian Academy of Health Sciences
- Professor of Pathology & Molecular Medicine, Biomedical & Molecular Sciences, and Oncology
Dr. Cole's Lab
Dr. Cole's Curriculum Vitae and Bibliography (modified for website)
Chart of Former & Present Lab Members
Mechanisms of Drug Sensitivity and Resistance: One focus of my research is the investigation of the molecular mechanisms of drug sensitivity and resistance that may be relevant to lung cancer and other human solid tumours. By using in vitro selected drug resistant lung cancer cell lines as model systems, we have previously identified two novel forms of resistance. One form of resistance is mediated by the drug efflux pump known as MRP1 (see below for more details). The other form of anticancer resistance we investigate is mediated through changes in the biology of the nuclear enzyme topoisomerase II (topo II) (see below for more details). My lab is also interested in understanding how novel titanocene containing drugs developed in the lab of our collaborator Dr. Mike Baird (Department of Chemistry) kill tumour cells. Cancer Training Project.
Transmembrane Transport of Chemical Toxicants and Organic Anions: In 1992 we cloned a novel mRNA from doxorubicin-selected multidrug resistant lung cancer cells. We then established that the plasma membrane protein encoded by this mRNA (the 190 kDa Multidrug Resistance Protein 1 or MRP1) could confer resistance to a broad spectrum of anticancer agents by acting as a drug efflux pump to reduce the accumulation of drugs in cells. We determined that the MRP1 gene is highly overexpressed (amplified) in many drug resistant tumor cell lines. MRP1 Amplification One measure of the impact of our discovery is the fact that our original paper in Science (1992) paper first describing MRP1 has now been cited > 1,780 times by other researchers (according to ISI Web of Science).
MRP1 belongs to the ATP-binding cassette (ABC) superfamily of transport proteins. The human ABC superfamily contains 49 genes and these have been divided into seven subfamilies - A through G Human ABC Superfamily. ABC genes are found in all species - drosophila have 56, yeast have 31, and even plants and sea urchins have a large number of these membrane transporters! Approximately 10 of the human ABC proteins can function as drug efflux pumps and require the binding and hydrolysis of ATP to perform this function.
MRP1 belongs to ABC subfamily C and its gene symbol is ABCC1. There are 13 genes in ABC subfamily C designated ABCC1 through ABCC13. Mutations in 5 of the 13 genes that make up the ABCC subfamily are known to be the cause of human genetic disorders of varying severity. Thus, mutations in MRP2 (ABCC2) cause a mild conjugated hyperbilirubinemia known as Dubin-Johnson Syndrome; mutations in the cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR) (ABCC7) cause cystic fibrosis; mutations in the sulfonylurea receptor SUR1 (ABCC8) which regulates the K+ channel Kir6.2 cause persistent hyperinsulinemic hypoglycemia of infancy (PHHI); mutations in ABCC6 (PXE, MRP6) are responsible for a connective tissue disorder known as Pseudoxanthoma elasticum.
An unrooted dendrogram illustrating the relative homology of the 13 ABCC genes to one another is shown in ABCC Family. Also shown is a cartoon model of the secondary structures of MRP1 and related ABCC proteins showing their transmembrane (TM) helices and nucleotide binding domains (NBDs) ABCC Transporters.
Substrate specificity of MRP1 and related transporters: Drugs transported out of cells by MRP1 include a structural diverse array of natural products like the anthracycline antibiotics (e.g. doxorubicin), the Vinca alkaloids (e.g. vincristine) and the epipodophyllotoxins (e.g. etoposide a.k.a VP-16). In addition, MRP1 can confer resistance to the antimetabolite methotrexate, the antiandrogen flutamide and to oxyanions containing arsenite and antimony. MRP2 and MRP3 have distinct but in the case of some drugs, overlapping substrate specificities with MRP1.
In addition to conferring resistance to anticancer drugs, MRP1 and several of its most closely related homologs are efficient transporters of GSH, and GSSG, as well as GSH, glucuronide and sulphate conjugated organic anions. MRP GSH Efflux Often these organic anion substrates of MRP1 are the products of Phase II drug metabolism (e.g. GSH conjugated cyclophosphamide). Endogenous organic anions known to be natural occurring substrates of MRP1 include the cysteinyl leukotriene LTC4. Metabolites of chemicals found in the environment (e.g. the GSH conjugate of the pesticide metolachlor; the glucuronide conjugate of the tobacco carcinogen NNAL) are also transported by MRP1 and MRP2. In addition, certain dietary components (e.g. bioflavonoids) can modulate the activity of MRP1.
One of our goals is to identify additional therapeutic agents, environmental chemicals and dietary components that are transported by MRP1 (and related proteins) or else modulate the expression or activity of these transporters.
Structure-function analyses of MRP1: Determining the detailed structure of large mammalian membrane proteins like MRP1 is technically very difficult. Consequently, we are collaborating with molecular modellers like Jeff Campbell in Mark Sansom's group at Oxford (UK) Sansom Group to develop 3D atomic models of MRP1 by homology modeling and molecular dynamics simulations. One of our ongoing goals is to use biochemical and biophysical approaches to test the validity of these models and refine them as necessary. J. Biol. Chem. 279: 463-368 (2004). These methods include mass spectroscopy, electron microscopy among others. J. Biol. Chem. 276: 16076-16082 (2001).
We and others have carried out a substantial number of structure-function studies of MRP1 (MRP2, MRP3) using site-directed mutagenesis to systematically mutate amino acids that we expect will affect the expression or function of the transporters in mammalian cell model systems. MRP1 Model In this way, we are getting a better idea of the specific amino acids that determine the remarkably broad substrate specificity of these transporters, as well as those amino acids that are key to the stable expression of the protein at the plasma membrane. MRP1 Confocal Mutant.
Pharmacogenetics of MRP1 (ABCC1): MRP1 and other related ABC transporters are also found in normal cells where they function in tissue defence [for a recent review on this subject, see Leslie et al.] [LINK when In Press]. Thus these proteins are expressed in tissues important for absorption (e.g. lung and gut) and metabolism and elimination (liver and kidney) of xenobiotics. ABC proteins also play an important role in maintaining pharmacological sanctuary sites [e.g. blood-brain barrier, blood-cerebral spinal fluid barrier, blood-testis barrier, and maternal-fetal barrier (placenta)] and thus are important determinants of the tissue disposition and elimination of drugs and other chemicals. Brain Placenta Genetic variation in drug metabolizing enzymes in different human populations are known to underlie a myriad of adverse drug reactions and interactions, and possibly play a role in cancer susceptibility. More recently, there has been a growing appreciation that variations in genes encoding membrane transport proteins such as the ABC transporters also play an important role in drug action and chemical toxicity. Consequently, another one of our goals is to determine whether naturally occurring mutations (single nucleotide polymorphisms - SNPs) of MRP1 (and other ABC proteins) affect the expression or function of the transporter.
(H-Index = 64; >17,210 Citations, June 2013)
Representative Publications (mostly last 7 years)
(selected from 225 total)
Review Articles (Invited)
Targeting the multidrug resistance protein (MRP1, ABCC1): past, present and
future. Ann. Rev. Pharmacol. Toxicol. 54: 95-117 (2014). (invited
review, impact factor 21.6).
Slot, S.V. Molinski and S.P.C. Cole. Multidrug resistance proteins. Essays
Biochem. 50: 179-207 (2011).
and R.G. Deeley. Transport of glutathione and glutathione conjugates by MRP1. Trends Pharm. Sci. 27: 438-446 (2006).
Deeley, C. Westlake and S.P.C. Cole. Transmembrane transport of endo-
and xenobiotics by the ATP-binding cassette multidrug resistance proteins
(MRPs). Physiol. Rev. 86: 849-899 (2006).
Conseil, R.G. Deeley and S.P.C. Cole. Polymorphisms of MRP1 (ABCC1) and
related ATP-dependent drug transporters. Pharmacogenet. Genomics
15: 523-533 (2005).
Structure and Function of MRP1 (selected)
Iram and S.P.C. Cole. Differential functional rescue of Lys513 and
Lys516 processing mutants of MRP1 (ABCC1) by chemical chaperones reveals
different domain-domain interactions of the transporter. Biochim.
Biophys. Acta 1838: 756-765 (2014).
Iram and S.P.C. Cole. Mutation of Glu521 or Glu535
in cytoplasmic loop 5 cause differential
misfolding in multiple domains of the multidrug and organic anion transporter
MRP1 (ABCC1). J. Biol. Chem. 287: 7543-7555 (2012).
Iram and S.P.C. Cole. Expression and function of human MRP1
(ABCC1) is dependent on amino acids in cytoplasmic loop 5 and its interface
with nucleotide binding domain 2. J. Biol. Chem. 286: 7202-7213
K. Maeno, A. Nakajima, G. Conseil, A. Rothnie, R.G. Deeley and S.P.C. Cole. Molecular basis for reduced estrone sulfate transport and altered modulator sensitivity of TM6 and TM17 mutants of MRP1 (ABCC1). Drug Metab. Dispos. 37: 1411-1420 (2009).
A. Rothnie, G. Conseil, A.Y.T. Lau, R.G. Deeley
and S.P.C. Cole. Mechanistic
differences between GSH transport by MRP1 (ABCC1) and GSH modulation of
MRP1-mediated transport. Mol. Pharmacol.
74: 1630-1640 (2008).
Wu, C.J. Oleschuk, Q. Mao, B.O. Keller, R.G. Deeley and S.P.C. Cole.
Analysis of human multidrug resistance protein 1 (ABCC1) by matrix-assisted
laser desorption ionization/time of flight mass spectrometry: toward
identification of leukotriene C4 binding sites. Mol. Pharmacol. 68:
Koike, G. Conseil, E.M. Leslie, R.G. Deeley and S.P.C. Cole.
Identification of proline residues in the core cytoplasmic and transmembrane
regions of multidrug resistance protein 1 (MRP1/ABCC1) important for transport
function, substrate specificity, and nucleotide interactions. J. Biol. Chem. 279:
Leslie, R.G. Deeley and S.P.C. Cole. Bioflavonoid stimulation of
glutathione transport by the 190-kDa multidrug resistance protein 1 (MRP1). Drug Metab. Dispos. 31:
Koike, C.J. Oleschuk, A. Haimeur, S.L. Olsen, R.G. Deeley and S.P.C. Cole.
Multiple membrane associated tryptophan residues contribute to the transport
activity and substrate specificity of the human multidrug resistance protein,
MRP1. J. Biol. Chem. 277:
Ito, C.J. Oleschuk, C. Westlake, M.Z. Vasa, R.G. Deeley and S.P.C. Cole.
Mutation of Trp1254 in the multispecific organic anion transporter, multidrug
resistance protein 2 (MRP2) (ABCC2), alters substrate specificity and results
in loss of methotrexate transport activity. J. Biol. Chem. 276:
Leslie, K. Ito, P. Upadhyaya, S.S. Hecht, R.G. Deeley and S.P.C. Cole.
Transport of the ß-O-glucuronide conjugate of the tobacco-specific carcinogen
4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) by the multidrug
resistance protein 1 (MRP1/ABCC1): Requirement for glutathione or a
non-sulfur-containing analog. J. Biol. Chem. 276:
G. Bhardwaj, J.H. Gerlach, J.E. Mackie, C.E. Grant, K.C. Almquist, A.J.
Stewart, E.U. Kurz, A.M.V. Duncan, and R.G. Deeley. Overexpression of a
transporter gene in a multidrug resistant human lung cancer cell line. Science 258: 1650-1654 (1992). [2,441
Conseil and S.P.C. Cole. Two polymorphic variants of ABCC1
selectively alter drug resistance and inhibitor sensitivity of the
multidrug and organic anion transporter MRP1. Drug Metab. Dispos. 41: 2187-2196 (2013).
Létourneau, R.G. Deeley and S.P.C. Cole. Functional characterization of
non-synonymous single nucleotide polymorphisms in the gene encoding human
multidrug resistance protein 1 (MRP1/ABCC1). Pharmacogenet. Genomics 15: 647-657 (2005).
Conrad, H-M. Kauffmann, K-i. Ito, E.M. Leslie, R.G. Deeley, D. Schrenk and S.P.C.
Cole. A naturally occurring mutation in MRP1 results in a selective
decrease in organic anion transport and in increased doxorubicin resistance. Pharmacogenetics 12:
Conrad, H-M. Kauffmann, K-i. Ito, R. Deeley, S.P.C. Cole and D. Schrenk.
Identification of human multidrug resistance protein 1 (MRP1) mutations and
characterization of a G671V substitution. J. Hum. Genet. 46:
T. Hoque, G. Conseil and S.P.C. Cole. Involvement of NHERF1 in apical
membrane localization of MRP4 in polarized kidney cells. Biochem. Biophys. Res. Commun. 379:
T. Hoque and S.P.C. Cole. Downregulation of NHERF1 increases expression
and function of multidrug resistance protein 4 (MRP4). Cancer Res. 68: 4802-4809 (2008).
updated: 27 Feb 2014