Susan P.C. Cole, PhD, FRSC, FCAHS

Email: spc.cole@queensu.ca
Office Phone: 613-533-2636
Lab: 613-533-6358; Fax: 613-533-6830

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 ResistanceOne 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 AnionsIn 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 MRP1Determining 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.

Career Bibliography

2013	2012	2011	2010	2009	2008	2007
2006	2005	2004	2003	2002	2001	2000
1999	1998	1997	1996	90-95	75-89

Representative Publications (mostly last 5 years) (selected from 219 total)

Review Articles (Invited)

E.M. Leslie, R.G. Deeley and S.P.C. Cole. Multidrug resistance proteins in toxicology: role of P-glycoprotein, MRP1, MRP2 and BCRP (ABCG2) in tissue defense. Toxicol. Appl. Pharmacol. 204: 216-237 (2005).

G. 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).

R.G. Deeley and S.P.C. Cole. Substrate recognition and transport by multidrug resistance protein 1 (ABCC1). FEBS Lett. 580: 1103-1111 (2006).

R.G. 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).

S.P.C. Cole and R.G. Deeley. Transport of glutathione and glutathione conjugates by MRP1. Trends Pharm. Sci. 27: 438-446 (2006) (invited, peer- reviewed).

A.J. Slot, S.V. Molinski and S.P.C. Cole. Multidrug resistance proteins. Essays Biochem. 50: 179-207 (2011). (invited, peer-reviewed).

Transport Mediated by MRP1 (selected)

S.P.C. Cole, 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).

E.M. Leslie, Q. Mao, C.J. Oleschuk, R.G. Deeley and S.P.C. Cole. Modulation of Multidrug Resistance Protein 1 (MRP1/ABCC1) transport and ATPase activities by interaction with dietary flavonoids. Mol. Pharmacol. 59: 1171-1180 (2001).

K. Ito, S.L. Olsen, W. Qiu, R.G. Deeley and S.P.C. Cole. Mutation of a single conserved tryptophan in multidrug resistance protein 1 (MRP1/ABCC1) results in loss of drug resistance and selective loss of organic anion transport. J. Biol. Chem. 276: 15616-15624 (2001).

E.M. 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: 27846-27854 (2001).

K. 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: 38108-38114 (2001).

S. 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: 656-663 (2001).

S. 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: 321-330 (2002).

K. 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: 49495-49503 (2002).

E.M. 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: 11-15 (2003).

K. 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: 12325-12336 (2004).

A. Haimeur, G. Conseil, R.G. Deeley and S.P.C. Cole. Mutations of charged amino acids in or proximal to the transmembrane helices of the second membrane spanning domain differentially affect the substrate specificity and transport activity of the multidrug resistance protein, MRP1 (ABCC1). Mol. Pharmacol. 65: 1375-1385 (2004).

D. Situ, A. Haimeur, G. Conseil, K.E. Sparks, D. Zhang, R.G. Deeley and S.P.C. Cole. Mutational analysis of ionizable residues proximal to the cytoplasmic interface of membrane spanning domain 3 of the multidrug resistance protein, MRP1 (ABCC1): Glutamate 1204 is important for both the expression and catalytic activity of the transporter. J. Biol. Chem. 279: 38871-38880 (2004).

I.J. Létourneau, R.J. Bowers, R.G. Deeley and S.P.C. Cole. Limited modulation of the transport activity of the human multidrug resistance proteins MRP1, MRP2 and MRP3 by nicotine glucuronide metabolites. Toxicol. Lett. 157: 9-19 (2005).

I.J. 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).

P. 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: 1455-1465 (2005).

A. Rothnie, R. Callaghan, R.G. Deeley and S.P.C. Cole. Role of GSH in estrone sulfate binding and translocation by the multidrug resistance protein 1 (MRP1, ABCC1). J. Biol. Chem. 281: 13906-13914 (2006)

M.K. DeGorter, G. Conseil, R.G. Deeley, R.L. Campbell and S.P.C. Cole.  Molecular modeling of the human multidrug resistance protein 1 (MRP1/ABCC1).  Biochem. Biophys. Res. Commun. 365: 29-34 (2008).

MRP4 Studies

Md. 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).

S.H. 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 (2011).

S.H. 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).

S.P. Ebert, B. Wetzel, R.L. Myette, G. Conseil, S.P.C. Cole, G.A. Sawada, T.W. Loo, M. C. Bartlett, D.M. Clarke and M.R. Detty. Chalcogenopyrylium compounds as modulators of the ATP-binding cassette transporters P-glycoprotein (P-gp/ABCB1) and multidrug resistance protein 1 (MRP1/ABCC1). J. Med. Chem. 55: 4683-4699 (2012).

last updated: 15 May 2013