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Jakobsen S, Nielsen CU. Exploring Amino Acid Transporters as Therapeutic Targets for Cancer: An Examination of Inhibitor Structures, Selectivity Issues, and Discovery Approaches. Pharmaceutics 2024; 16:197. [PMID: 38399253 PMCID: PMC10893028 DOI: 10.3390/pharmaceutics16020197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/18/2024] [Accepted: 01/28/2024] [Indexed: 02/25/2024] Open
Abstract
Amino acid transporters are abundant amongst the solute carrier family and have an important role in facilitating the transfer of amino acids across cell membranes. Because of their impact on cell nutrient distribution, they also appear to have an important role in the growth and development of cancer. Naturally, this has made amino acid transporters a novel target of interest for the development of new anticancer drugs. Many attempts have been made to develop inhibitors of amino acid transporters to slow down cancer cell growth, and some have even reached clinical trials. The purpose of this review is to help organize the available information on the efforts to discover amino acid transporter inhibitors by focusing on the amino acid transporters ASCT2 (SLC1A5), LAT1 (SLC7A5), xCT (SLC7A11), SNAT1 (SLC38A1), SNAT2 (SLC38A2), and PAT1 (SLC36A1). We discuss the function of the transporters, their implication in cancer, their known inhibitors, issues regarding selective inhibitors, and the efforts and strategies of discovering inhibitors. The goal is to encourage researchers to continue the search and development within the field of cancer treatment research targeting amino acid transporters.
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Affiliation(s)
- Sebastian Jakobsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark
| | - Carsten Uhd Nielsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark
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2
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Nielsen CU, Bjerg M, Ulaganathan N, Holm R. Oral and intravenous pharmacokinetics of taurine in sprague-dawley rats: the influence of dose and the possible involvement of the proton-coupled amino acid transporter, PAT1, in oral taurine absorption. Physiol Rep 2017; 5:5/19/e13467. [PMID: 29038364 PMCID: PMC5641942 DOI: 10.14814/phy2.13467] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 08/30/2017] [Accepted: 09/10/2017] [Indexed: 11/24/2022] Open
Abstract
Taurine is involved in various physiological processes, and one of the most abundant amino acids in human. The aim was to investigate the mechanism for intestinal absorption of taurine in vivo using also in vitro mechanistic studies. Taurine absorption was measured in male Sprague‐Dawley rats at 10–997 mg/kg and 1–30 mg/kg for oral and intravenous administration, respectively. Oral absorption was measured in the presence of substrates for the proton‐coupled amino acid transporter, PAT1, that is, 200 mg/kg proline (Pro) and sarcosine (Sar), and in the presence of 2‐Amino‐2‐norbornanecarboxylic acid (BCH) (200 mg/kg). BCH is not an inhibitor of PAT1 or the taurine transporter, TauT, hence it was included as a negative control. In vitro studies investigating the transport mechanism of taurine were conducted in human intestinal Caco‐2 cells. The pharmacokinetic investigations showed that intestinal taurine absorption was not saturable at the investigated doses, but that the time (tmax) to reach the maximal plasma concentration (Cmax) increased with dose. Furthermore, Sar and Pro, but not BCH, decreased taurine Cmax. In vitro it was clearly shown that PAT1 mediated the cellular uptake of taurine and thereby facilitated the transepithelial taurine transport, which could be inhibited by Pro and Sar, but not BCH. In vivo and in vitro results suggest that taurine absorption from the intestine is caused by PAT1.
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Affiliation(s)
- Carsten Uhd Nielsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark
| | - Maria Bjerg
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark
| | - Nithiya Ulaganathan
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark
| | - René Holm
- Pharmaceutical Science and CMC Biologics, H. Lundbeck A/S, Valby, Denmark
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Yu Y, Wang M, Zhang K, Yang D, Zhong Y, An J, Lei B, Zhang X. The transepithelial transport mechanism of polybrominated diphenyl ethers in human intestine determined using a Caco-2 cell monolayer. ENVIRONMENTAL RESEARCH 2017; 154:93-100. [PMID: 28056407 DOI: 10.1016/j.envres.2016.12.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 12/02/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Abstract
Oral ingestion plays an important role in human exposure to polybrominated diphenyl ethers (PBDEs). The uptake of PBDEs primarily occurs in the small intestine. The aim of the present study is to investigate the transepithelial transport characteristics and mechanisms of PBDEs in the small intestine using a Caco-2 cell monolayer model. The apparent permeability coefficients of PBDEs indicated that tri- to hepta-BDEs were poorly absorbed compounds. A linear increase in transepithelial transport was observed with various concentrations of PBDEs, which suggested that passive diffusion dominated their transport at the concentration range tested. In addition, the pseudo-first-order kinetics equation can be applied to the transepithelial transport of PBDEs. The rate-determining step in transepithelial transport of PBDEs was trans-cell transport including the trans-pore process. The significantly lower transepithelial transport rates at low temperature for bidirectional transepithelial transport suggested that an energy-dependent transport mechanism was involved. The efflux transporters (P-glycoprotein, multidrug resistance-associated protein, and breast cancer resistance protein) and influx transporters (organic cation transporters) participated in the transepithelial transport of PBDEs. In addition, the transepithelial transport of PBDEs was pH sensitive; however, more information is required to understand the influence of pH.
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Affiliation(s)
- Yingxin Yu
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China.
| | - Mengmeng Wang
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Kaiqiong Zhang
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Dan Yang
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Yufang Zhong
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Jing An
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Bingli Lei
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Xinyu Zhang
- Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
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Intestinal transport of Cylindrospermopsin using the Caco-2 cell line. Toxicol In Vitro 2017; 38:142-149. [DOI: 10.1016/j.tiv.2016.09.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/14/2016] [Accepted: 09/25/2016] [Indexed: 11/22/2022]
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Al-Saraf A, Holm R, Nielsen CU. Tween 20 increases intestinal transport of doxorubicin in vitro but not in vivo. Int J Pharm 2015; 498:66-9. [PMID: 26685728 DOI: 10.1016/j.ijpharm.2015.12.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/02/2015] [Accepted: 12/09/2015] [Indexed: 10/22/2022]
Abstract
The chemotherapeutic drug substance doxorubicin has been reported to be a substrate of P-gp, which induces a barrier for oral administration and leads to a bioavailability of 3% in male Sprague Dawley rats. Literature studies have reported increased transport of P-pg substrates, like digoxin, when co-administered with P-gp inhibitors (non-ionic surfactants) in vitro and in vivo . The aim of the present study was thus to investigate if different non-ionic surfactants would have a similar effect on the in vitro and in vivo absorption of doxorubicin. This was investigated in vitro in Caco-2 cells and by oral co-administration of doxorubicin together with tween 20 to male Sprague Dawley rats. 200 μM (0.025%) tween 20 increased the intestinal absorptive permeability of doxorubicin in vitro by 48 ± 4% from 8.8 × 10(-6)cm/s to 13.0 × 10(-6)cm/s. Further, the efflux ratio was reduced from 2.2 ± 0.06 to 1.2 ± 0.03 (n=3-7). In vivo, co-administration of doxorubicin and 0-25% tween 20 did not yield detectable doxorubicin plasma concentrations, probably due to extensive intestinal metabolism. In conclusion, the present study demonstrated that non-ionic surfactants increased the transport of doxorubicin in vitro, most likely by inhibition of the efflux activity. However, this effect was not transferable to the in vivo situation.
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Affiliation(s)
- Amal Al-Saraf
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - René Holm
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark; Pharmaceutical Science and CMC Biologics, H. Lundbeck A/S, DK-2500 Valby, Denmark
| | - Carsten Uhd Nielsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
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Rasmussen RN, Lagunas C, Plum J, Holm R, Nielsen CU. Interaction of GABA-mimetics with the taurine transporter (TauT, Slc6a6) in hyperosmotic treated Caco-2, LLC-PK1 and rat renal SKPT cells. Eur J Pharm Sci 2015; 82:138-46. [PMID: 26631583 DOI: 10.1016/j.ejps.2015.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/11/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
Abstract
The aim of the present study was to investigate if basic GABA-mimetics interact with the taurine transporter (TauT, Slc6a6), and to find a suitable cell based model that is robust towards extracellular changes in osmolality during uptake studies. Taurine uptake was measured in human Caco-2 cells, porcine LLC-PK1 cells, and rat SKPT cells using radiolabelled taurine. Hyperosmotic conditions were obtained by incubation with raffinose (final osmolality of 500mOsm) for 24h prior to the uptake experiments. Expression of the taurine transporter, TauT, was investigated at the mRNA level by real-time PCR. Uptake of the GABA-mimetics gaboxadol and vigabatrin was investigated in SKPT cells, and quantified by liquid scintillation or HPLC-MS/MS analysis, respectively. The uptake rate of [(3)H]-taurine was Na(+) and Cl(-) and concentration dependent with taurine with an apparent Vmax of 6.3±1.6pmolcm(-2)min(-1) and a Km of 24.9±15.0μM. β-alanine, nipecotic acid, gaboxadol, GABA, vigabatrin, δ-ALA and guvacine inhibited the taurine uptake rate in a concentration dependent manner. The order of affinity for TauT was β-alanine>GABA>nipecotic acid>guvacine>δ-ALA>vigabatrin>gaboxadol with IC50-values of 0.04, 1.07, 2.02, 4.19, 4.94, 31.4 and 39.9mM, respectively. In conclusion, GABA mimetics inhibited taurine uptake in hyperosmotic rat renal SKPT cells. SKPT cells, which seem to be a useful model for investigating taurine transport in the short-term presence of high concentrations of osmolytes. Furthermore, analogues of β-alanine appear to have higher affinities for TauT than GABA-analogues.
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Affiliation(s)
- Rune Nørgaard Rasmussen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK 5230 Odense M, Denmark
| | - Candela Lagunas
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, Universitetsparken 2, DK 2100, Copenhagen, Denmark
| | - Jakob Plum
- Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, Universitetsparken 2, DK 2100, Copenhagen, Denmark
| | - René Holm
- Pharmaceutical Science and CMC Biologics, H. Lundbeck A/S, DK 2500, Valby, Denmark
| | - Carsten Uhd Nielsen
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK 5230 Odense M, Denmark.
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Nøhr M, Juul R, Thale Z, Holm R, Kreilgaard M, Nielsen C. Is oral absorption of vigabatrin carrier-mediated? Eur J Pharm Sci 2015; 69:10-8. [DOI: 10.1016/j.ejps.2014.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/17/2014] [Accepted: 12/25/2014] [Indexed: 01/28/2023]
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Nøhr MK, Thale ZI, Brodin B, Hansen SH, Holm R, Nielsen CU. Intestinal absorption of the antiepileptic drug substance vigabatrin is altered by infant formula in vitro and in vivo. Pharmacol Res Perspect 2014; 2:e00036. [PMID: 25505585 PMCID: PMC4184708 DOI: 10.1002/prp2.36] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 02/25/2014] [Indexed: 11/25/2022] Open
Abstract
Vigabatrin is an antiepileptic drug substance mainly used in pediatric treatment of infantile spasms. The main source of nutrition for infants is breast milk and/or infant formula. Our hypothesis was that infant formula may affect the intestinal absorption of vigabatrin. The aim was therefore to investigate the potential effect of coadministration of infant formula with vigabatrin on the oral absorption in vitro and in vivo. The effect of vigabatrin given with an infant formula on the oral uptake and transepithelial transport was investigated in vitro in Caco-2 cells. In vivo effects of infant formula and selected amino acids on the pharmacokinetic profile of vigabatrin was investigated after oral coadministration to male Sprague–Dawley rats using acetaminophen as a marker for gastric emptying. The presence of infant formula significantly reduced the uptake rate and permeability of vigabatrin in Caco-2 cells. Oral coadministration of vigabatrin and infant formula significantly reduced Cmax and prolonged tmax of vigabatrin absorption. Ligands for the proton-coupled amino acid transporter PAT1, sarcosine, and proline/l-tryptophan had similar effects on the pharmacokinetic profile of vigabatrin. The infant formula decreased the rate of gastric emptying. Here we provide experimental evidence for an in vivo role of PAT1 in the intestinal absorption of vigabatrin. The effect of infant formula on the oral absorption of vigabatrin was found to be due to delayed gastric emptying, however, it seems reasonable that infant formula may also directly affect the intestinal absorption rate of vigabatrin possibly via PAT1.
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Affiliation(s)
- Martha Kampp Nøhr
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen DK-2100, Copenhagen, Denmark
| | - Zia I Thale
- Department of Bioanalysis, H. Lundbeck A/S DK-2500, Valby, Denmark
| | - Birger Brodin
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen DK-2100, Copenhagen, Denmark
| | - Steen H Hansen
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen DK-2100, Copenhagen, Denmark
| | - René Holm
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen DK-2100, Copenhagen, Denmark ; Biologics and Pharmaceutical Science, H. Lundbeck A/S DK-2500, Valby, Denmark
| | - Carsten Uhd Nielsen
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen DK-2100, Copenhagen, Denmark
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Plum J, Nøhr MK, Hansen SH, Holm R, Nielsen CU. The anti-epileptic drug substance vigabatrin inhibits taurine transport in intestinal and renal cell culture models. Int J Pharm 2014; 473:395-7. [PMID: 25062867 DOI: 10.1016/j.ijpharm.2014.07.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 07/17/2014] [Indexed: 10/25/2022]
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Pharmacokinetic aspects of the anti-epileptic drug substance vigabatrin: focus on transporter interactions. Ther Deliv 2014; 5:927-42. [DOI: 10.4155/tde.14.55] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Drug transporters in various tissues, such as intestine, kidney, liver and brain, are recognized as important mediators of absorption, distribution, metabolism and excretion of drug substances. This review gives a current status on the transporter(s) mediating the absorption, distribution, metabolism and excretion properties of the anti-epileptic drug substance vigabatrin. For orally administered drugs, like vigabatrin, the absorption from the intestine is a prerequisite for the bioavailability. Therefore, transporter(s) involved in the intestinal absorption of vigabatrin in vitro and in vivo are discussed in detail. Special focus is on the contribution of the proton-coupled amino acid transporter 1 (PAT1) for intestinal vigabatrin absorption. Furthermore, the review gives an overview of the pharmacokinetic parameters of vigabatrin across different species and drug–food and drug–drug interactions involving vigabatrin.
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Nøhr MK, Holm R, Thale ZI, Nielsen CU. Intestinal absorption of the antiepileptic drug substance vigabatrin in Göttingen mini-pigs is unaffected by co-administration of amino acids. Int J Pharm 2014; 466:18-20. [DOI: 10.1016/j.ijpharm.2014.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/28/2014] [Accepted: 03/01/2014] [Indexed: 01/21/2023]
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