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Blanc Mettral J, Faller N, Cruchon S, Sottas L, Buclin T, Schild L, Choong E, Nahimana A, Decosterd LA. Imatinib Uptake into Cells is Not Mediated by Organic Cation Transporters OCT1, OCT2, or OCT3, But is Influenced by Extracellular pH. Drug Metab Lett 2019; 13:102-110. [PMID: 30734690 DOI: 10.2174/1872312813666190207150207] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 01/23/2019] [Accepted: 02/10/2020] [Indexed: 06/09/2023]
Abstract
BACKGROUND Cancer cells undergo genetic and environmental changes that can alter cellular disposition of drugs, notably by alterations of transmembrane drug transporters expression. Whether the influx organic cation transporter 1 (OCT1) encoded by the gene SLC221A1 is implicated in the cellular uptake of imatinib is still controversial. Besides, imatinib ionization state may be modulated by the hypoxic acidic surrounding extracellular microenvironment. OBJECTIVE To determine the functional contribution of OCTs and extracellular pH on imatinib cellular disposition. METHODS We measured imatinib uptake in two different models of selective OCTs drug transporter expression (transfected Xenopus laevis oocytes and OCT-expressing HEK293 human cells), incubated at pH 7.4 and 6, using specific mass spectrometry analysis. RESULTS Imatinib cellular uptake occurred independently of OCT1- OCT2- or OCT3-mediated drug transport at pH 7.4. Uptake of the OCTs substrate tetraethylammonium in oocytes remained intact at pH 6, while the accumulation of imatinib in oocytes was 10-fold lower than at pH 7.4, irrespectively of OCTs expressions. In OCT1- and OCT2-HEK cells at pH 6, imatinib accumulation was reduced by 2- 3-fold regardless of OCTs expressions. Since 99.5% of imatinib at pH6 is under the cationic form, the reduced cellular accumulation of imatinib at such pH may be explained by the lower amount of uncharged imatinib remaining for passive diffusion across cellular membrane. CONCLUSION Imatinib is not a substrate of OCTs 1-3 while the environmental pH modulates cellular disposition of imatinib. The observation that a slightly acidic extracellular pH influences imatinib cellular accumulation is important, considering the low extracellular pH reported in the hematopoietic leukemia/ cancer cell microenvironment.
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Affiliation(s)
- Jaurès Blanc Mettral
- Laboratory of Clinical Pharmacology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Faller
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Sandra Cruchon
- Laboratory of Clinical Pharmacology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Loïc Sottas
- Laboratory of Clinical Pharmacology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Thierry Buclin
- Service of Clinical Pharmacology, Department of Laboratories, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Laurent Schild
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Eva Choong
- Laboratory of Clinical Pharmacology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Aimable Nahimana
- Research Laboratory of Haematology, Department of Medicine, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Laurent A Decosterd
- Laboratory of Clinical Pharmacology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
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Watkins DB, Hughes TP, White DL. OCT1 and imatinib transport in CML: is it clinically relevant? Leukemia 2015; 29:1960-9. [PMID: 26122430 DOI: 10.1038/leu.2015.170] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 04/30/2015] [Accepted: 05/01/2015] [Indexed: 12/15/2022]
Abstract
Imatinib is a highly effective therapy for chronic phase-chronic myeloid leukaemia (CP-CML) patients; however, responses to frontline imatinib are variable. The human organic cation transporter 1 (OCT1; SLC22A1) has been reported to be the main influx transporter involved in imatinib uptake into CML cells. Furthermore, variation in the efficiency of imatinib influx via OCT1 has been demonstrated to result in the inter-patient variation observed in primary response to imatinib. Although studies have questioned the role of OCT1 in imatinib influx, these have been largely performed in non-clinical settings. Measuring both OCT1 mRNA levels and the functional activity of OCT1 in primary leukaemic cells has been demonstrated to predict molecular response and outcome in imatinib-treated CP-CML patients in several independent studies. Here, the role of OCT1 and OCT1 genetic variants in imatinib uptake and response prediction is summarised and data generated from model systems assessing the role of OCT1 in imatinib transport is discussed.
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Affiliation(s)
- D B Watkins
- Leukaemia Research Group, Cancer Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - T P Hughes
- Leukaemia Research Group, Cancer Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia.,School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.,Department of Haematology, SA Pathology, Adelaide, South Australia, Australia
| | - D L White
- Leukaemia Research Group, Cancer Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia.,School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.,Discipline of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
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Burger H, den Dekker AT, Segeletz S, Boersma AWM, de Bruijn P, Debiec-Rychter M, Taguchi T, Sleijfer S, Sparreboom A, Mathijssen RHJ, Wiemer EAC. Lysosomal Sequestration Determines Intracellular Imatinib Levels. Mol Pharmacol 2015; 88:477-87. [PMID: 26108972 DOI: 10.1124/mol.114.097451] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 06/24/2015] [Indexed: 11/22/2022] Open
Abstract
The intracellular uptake and retention (IUR) of imatinib is reported to be controlled by the influx transporter SLC22A1 (organic cation transporter 1). We recently hypothesized that alternative uptake and/or retention mechanisms exist that determine intracellular imatinib levels. Here, we systematically investigate the nature of these mechanisms. Imatinib uptake in cells was quantitatively determined by liquid chromatography-tandem mass spectrometry. Fluorescent microscopy was used to establish subcellular localization of imatinib. Immunoblotting, cell cycle analyses, and apoptosis assays were performed to evaluate functional consequences of imatinib sequestration. Uptake experiments revealed high intracellular imatinib concentrations in HEK293, the leukemic cell lines K562 and SD-1, and a gastrointestinal stromal tumor cell line GIST-T1. We demonstrated that imatinib IUR is time-, dose-, temperature-, and energy-dependent and provide evidence that SLC22A1 and other potential imatinib transporters do not substantially contribute to the IUR of imatinib. Prazosin, amantadine, NH4Cl, and the vacuolar ATPase inhibitor bafilomycin A1 significantly decreased the IUR of imatinib and likely interfere with lysosomal retention and accumulation of imatinib. Costaining experiments with LysoTracker Red confirmed lysosomal sequestration of imatinib. Inhibition of the lysosomal sequestration had no effect on the inhibition of c-Kit signaling and imatinib-mediated cell cycle arrest but significantly increased apoptosis in imatinib-sensitive GIST-T1 cells. We conclude that intracellular imatinib levels are primarily determined by lysosomal sequestration and do not depend on SLC22A1 expression.
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Affiliation(s)
- Herman Burger
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Alexander T den Dekker
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Sandra Segeletz
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Antonius W M Boersma
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Peter de Bruijn
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Maria Debiec-Rychter
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Takahiro Taguchi
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Stefan Sleijfer
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Alex Sparreboom
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Ron H J Mathijssen
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
| | - Erik A C Wiemer
- Department of Medical Oncology, Erasmus University Medical Center, Erasmus MC Cancer Institute, Rotterdam, The Netherlands (H.B., A.T.D., S.Se., A.W.M.B., P.B., S.Sl., R.H.J.M., E.A.C.W.); Department of Human Genetics, Catholic University Leuven and University Hospitals, Leuven, Belgium (M.D.-R.); Division of Human Health and Medical Science, Graduate School of Kuroshio Science, Kochi University, Nankoku, Kochi, Japan (T.T.); and Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee (A.S.)
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Nies AT, Schaeffeler E, van der Kuip H, Cascorbi I, Bruhn O, Kneba M, Pott C, Hofmann U, Volk C, Hu S, Baker SD, Sparreboom A, Ruth P, Koepsell H, Schwab M. Cellular uptake of imatinib into leukemic cells is independent of human organic cation transporter 1 (OCT1). Clin Cancer Res 2013; 20:985-94. [PMID: 24352644 DOI: 10.1158/1078-0432.ccr-13-1999] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE In addition to mutated BCR-ABL1 kinase, the organic cation transporter 1 (OCT1, encoded by SLC22A1) has been considered to contribute to imatinib resistance in patients with chronic myeloid leukemia (CML). As data are conflicting as to whether OCT1 transports imatinib and may serve as a clinical biomarker, we used a combination of different approaches including animal experiments to elucidate comprehensively the impact of OCT1 on cellular imatinib uptake. EXPERIMENTAL DESIGN Transport of imatinib was studied using OCT1-expressing Xenopus oocytes, mammalian cell lines (HEK293, MDCK, V79) stably expressing OCT1, human leukemic cells, and Oct1-knockout mice. OCT1 mRNA and protein expression were analyzed in leukemic cells from patients with imatinib-naïve CML as well as in cell lines. RESULTS Transport and inhibition studies showed that overexpression of functional OCT1 protein in Xenopus oocytes or mammalian cell lines did not lead to an increased cellular accumulation of imatinib. The CML cell lines (K562, Meg-01, LAMA84) and leukemic cells from patients expressed neither OCT1 mRNA nor protein as demonstrated by immunoblotting and immunofluorescence microscopy, yet they showed a considerable imatinib uptake. Oct1 deficiency in mice had no influence on plasma and hepatic imatinib concentrations. CONCLUSIONS These data clearly demonstrate that cellular uptake of imatinib is independent of OCT1, and therefore OCT1 is apparently not a valid biomarker for imatinib resistance.
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Affiliation(s)
- Anne T Nies
- Authors' Affiliations: Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, and University of Tübingen; Institute of Pharmacy, Department of Pharmacology, University of Tübingen; Department of Clinical Pharmacology, University Hospital Tübingen, Tübingen; Institute of Experimental and Clinical Pharmacology, Second Medical Department, University Hospital Schleswig-Holstein, Campus Kiel; Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany; and Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, Tennessee
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