Elevated glutathione levels confer cellular sensitization to cisplatin toxicity by up-regulation of copper transporter hCtr1

Helen H.W Chen, Im Sook Song, Anwar Hossain, Min Koo Choi, Yoshiaki Yamane, Zheng D. Liang, Jia Lu, Lily Y.H. Wu, Zahid H. Siddik, Leo W.J. Klomp, Niramol Savaraj, Macus Tien Kuo

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Abstract

Previous studies have demonstrated that treating cultured cells with cisplatin (CDDP) up-regulated the expression of glutathione (GSH) and its de novo rate-limiting enzyme glutamate-cysteine ligase (GCL), which consists of a catalytic (GCLC) and a modifier (GCLM) subunit. It has also been shown that many CDDP-resistant cell lines exhibit high levels of GCLC/GCLM and GSH. Because the GSH system is the major intracellular regulator of redox conditions that serve as an important detoxification cytoprotector, these results have been taken into consideration that elevated levels of GCL/GSH are responsible for the CDDP resistance. In contrast to this context, we demonstrated here that overexpression of GSH by transfection with an expression plasmid containing the GCLC cDNA conferred sensitization to CDDP through up-regulation of human copper transporter (hCtr) 1, which is also a transporter for CDDP. Depleting GSH levels in these transfected cells reversed CDDP sensitivity with concomitant reduction of hCtr1 expression. Although rates of copper transport were also up-regulated in the transfected cells, these cells exhibited biochemical signature of copper deficiency, suggesting that GSH functions as an intracellular copper-chelator and that overexpression of GSH can alter copper metabolism. More importantly, our results reveal a new role of GSH in the regulation of CDDP sensitivity. Overproduction of GSH depletes the bioavailable copper pool, leading to upregulation of hCtr1 and sensitization of CDDP transport and cell killing. These findings also have important implications in that modulation of the intracellular copper pool may be a novel strategy for improving chemotherapeutic efficacy of platinum-based antitumor agents.

Original languageEnglish
Pages (from-to)697-704
Number of pages8
JournalMolecular Pharmacology
Volume74
Issue number3
DOIs
Publication statusPublished - 2008 Sep 1

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Cisplatin
Glutathione
Copper
Up-Regulation
Glutamate-Cysteine Ligase
Chelating Agents
Platinum
Antineoplastic Agents
Oxidation-Reduction
Transfection
Cultured Cells
Plasmids
Complementary DNA
Cell Line
Enzymes

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Pharmacology

Cite this

Chen, Helen H.W ; Song, Im Sook ; Hossain, Anwar ; Choi, Min Koo ; Yamane, Yoshiaki ; Liang, Zheng D. ; Lu, Jia ; Wu, Lily Y.H. ; Siddik, Zahid H. ; Klomp, Leo W.J. ; Savaraj, Niramol ; Kuo, Macus Tien. / Elevated glutathione levels confer cellular sensitization to cisplatin toxicity by up-regulation of copper transporter hCtr1. In: Molecular Pharmacology. 2008 ; Vol. 74, No. 3. pp. 697-704.
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title = "Elevated glutathione levels confer cellular sensitization to cisplatin toxicity by up-regulation of copper transporter hCtr1",
abstract = "Previous studies have demonstrated that treating cultured cells with cisplatin (CDDP) up-regulated the expression of glutathione (GSH) and its de novo rate-limiting enzyme glutamate-cysteine ligase (GCL), which consists of a catalytic (GCLC) and a modifier (GCLM) subunit. It has also been shown that many CDDP-resistant cell lines exhibit high levels of GCLC/GCLM and GSH. Because the GSH system is the major intracellular regulator of redox conditions that serve as an important detoxification cytoprotector, these results have been taken into consideration that elevated levels of GCL/GSH are responsible for the CDDP resistance. In contrast to this context, we demonstrated here that overexpression of GSH by transfection with an expression plasmid containing the GCLC cDNA conferred sensitization to CDDP through up-regulation of human copper transporter (hCtr) 1, which is also a transporter for CDDP. Depleting GSH levels in these transfected cells reversed CDDP sensitivity with concomitant reduction of hCtr1 expression. Although rates of copper transport were also up-regulated in the transfected cells, these cells exhibited biochemical signature of copper deficiency, suggesting that GSH functions as an intracellular copper-chelator and that overexpression of GSH can alter copper metabolism. More importantly, our results reveal a new role of GSH in the regulation of CDDP sensitivity. Overproduction of GSH depletes the bioavailable copper pool, leading to upregulation of hCtr1 and sensitization of CDDP transport and cell killing. These findings also have important implications in that modulation of the intracellular copper pool may be a novel strategy for improving chemotherapeutic efficacy of platinum-based antitumor agents.",
author = "Chen, {Helen H.W} and Song, {Im Sook} and Anwar Hossain and Choi, {Min Koo} and Yoshiaki Yamane and Liang, {Zheng D.} and Jia Lu and Wu, {Lily Y.H.} and Siddik, {Zahid H.} and Klomp, {Leo W.J.} and Niramol Savaraj and Kuo, {Macus Tien}",
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doi = "10.1124/mol.108.047969",
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Chen, HHW, Song, IS, Hossain, A, Choi, MK, Yamane, Y, Liang, ZD, Lu, J, Wu, LYH, Siddik, ZH, Klomp, LWJ, Savaraj, N & Kuo, MT 2008, 'Elevated glutathione levels confer cellular sensitization to cisplatin toxicity by up-regulation of copper transporter hCtr1', Molecular Pharmacology, vol. 74, no. 3, pp. 697-704. https://doi.org/10.1124/mol.108.047969

Elevated glutathione levels confer cellular sensitization to cisplatin toxicity by up-regulation of copper transporter hCtr1. / Chen, Helen H.W; Song, Im Sook; Hossain, Anwar; Choi, Min Koo; Yamane, Yoshiaki; Liang, Zheng D.; Lu, Jia; Wu, Lily Y.H.; Siddik, Zahid H.; Klomp, Leo W.J.; Savaraj, Niramol; Kuo, Macus Tien.

In: Molecular Pharmacology, Vol. 74, No. 3, 01.09.2008, p. 697-704.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Elevated glutathione levels confer cellular sensitization to cisplatin toxicity by up-regulation of copper transporter hCtr1

AU - Chen, Helen H.W

AU - Song, Im Sook

AU - Hossain, Anwar

AU - Choi, Min Koo

AU - Yamane, Yoshiaki

AU - Liang, Zheng D.

AU - Lu, Jia

AU - Wu, Lily Y.H.

AU - Siddik, Zahid H.

AU - Klomp, Leo W.J.

AU - Savaraj, Niramol

AU - Kuo, Macus Tien

PY - 2008/9/1

Y1 - 2008/9/1

N2 - Previous studies have demonstrated that treating cultured cells with cisplatin (CDDP) up-regulated the expression of glutathione (GSH) and its de novo rate-limiting enzyme glutamate-cysteine ligase (GCL), which consists of a catalytic (GCLC) and a modifier (GCLM) subunit. It has also been shown that many CDDP-resistant cell lines exhibit high levels of GCLC/GCLM and GSH. Because the GSH system is the major intracellular regulator of redox conditions that serve as an important detoxification cytoprotector, these results have been taken into consideration that elevated levels of GCL/GSH are responsible for the CDDP resistance. In contrast to this context, we demonstrated here that overexpression of GSH by transfection with an expression plasmid containing the GCLC cDNA conferred sensitization to CDDP through up-regulation of human copper transporter (hCtr) 1, which is also a transporter for CDDP. Depleting GSH levels in these transfected cells reversed CDDP sensitivity with concomitant reduction of hCtr1 expression. Although rates of copper transport were also up-regulated in the transfected cells, these cells exhibited biochemical signature of copper deficiency, suggesting that GSH functions as an intracellular copper-chelator and that overexpression of GSH can alter copper metabolism. More importantly, our results reveal a new role of GSH in the regulation of CDDP sensitivity. Overproduction of GSH depletes the bioavailable copper pool, leading to upregulation of hCtr1 and sensitization of CDDP transport and cell killing. These findings also have important implications in that modulation of the intracellular copper pool may be a novel strategy for improving chemotherapeutic efficacy of platinum-based antitumor agents.

AB - Previous studies have demonstrated that treating cultured cells with cisplatin (CDDP) up-regulated the expression of glutathione (GSH) and its de novo rate-limiting enzyme glutamate-cysteine ligase (GCL), which consists of a catalytic (GCLC) and a modifier (GCLM) subunit. It has also been shown that many CDDP-resistant cell lines exhibit high levels of GCLC/GCLM and GSH. Because the GSH system is the major intracellular regulator of redox conditions that serve as an important detoxification cytoprotector, these results have been taken into consideration that elevated levels of GCL/GSH are responsible for the CDDP resistance. In contrast to this context, we demonstrated here that overexpression of GSH by transfection with an expression plasmid containing the GCLC cDNA conferred sensitization to CDDP through up-regulation of human copper transporter (hCtr) 1, which is also a transporter for CDDP. Depleting GSH levels in these transfected cells reversed CDDP sensitivity with concomitant reduction of hCtr1 expression. Although rates of copper transport were also up-regulated in the transfected cells, these cells exhibited biochemical signature of copper deficiency, suggesting that GSH functions as an intracellular copper-chelator and that overexpression of GSH can alter copper metabolism. More importantly, our results reveal a new role of GSH in the regulation of CDDP sensitivity. Overproduction of GSH depletes the bioavailable copper pool, leading to upregulation of hCtr1 and sensitization of CDDP transport and cell killing. These findings also have important implications in that modulation of the intracellular copper pool may be a novel strategy for improving chemotherapeutic efficacy of platinum-based antitumor agents.

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