6-mercaptopurine transport in human lymphocytes: Correlation with drug-induced cytotoxicity

Laurie S. Conklin, Carmelo Cuffari, Toshihiko Okazaki, Yinglei Miao, Bahman Saatian, Tian E. Chen, Chung Ming Tse, Steven R. Brant, Xuhang Li

Research output: Contribution to journalArticle

Abstract

Objective: 6-mercaptopurine (6-MP) is efficacious in the treatment of inflammatory bowel disease (IBD). However, about one-third of patients respond poorly to therapy. This study aimed to characterize the inherent differences in 6-MP transport that may cotribute to the differences in treatment responses. METHODS: Intracellular 6-MP accumulation was assayed in Epstein-Barr virus (EBV)-transformed lymphocytes from IBD patients, using 14C-radiolabeled 6-MP. Cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) assay. Apoptosis was assayed based on the activation of caspase 3. The expressions of 15 potential 6-MP transporters were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Intracellular 6-MP accumulation, varying significantly among patients, was carrier-dependent and partially sodium-dependent. 6-MP cytotoxicity was, at least in part, due to apoptosis and correlated with intracellular drug accumulation. The efflux transporters did not appear to contribute to the variability of intracellular drug accumulation between patients, since none correlated with drug accumulation or cytotoxicity. Rather, differential expression of five influx/uptake transporters might be a key contributor to the difference in the accumulation of and susceptibility to the drug. CONCLUSIONS: The heterogeneity of the drug transporters may be the reason for the therapeutic sensitivity of 6-MP in IBD patients. As the 6-MP uptake is a carrier-mediated and partially sodium-dependent process, future studies are necessary to evaluate the role of the putative transporters and their correlation with drug sensitivity in patients.

Original languageEnglish (US)
Pages (from-to)82-93
Number of pages12
JournalJournal of Digestive Diseases
Volume13
Issue number2
DOIs
StatePublished - Feb 2012

Fingerprint

6-Mercaptopurine
Lymphocytes
Pharmaceutical Preparations
Inflammatory Bowel Diseases
Sodium
Apoptosis
Therapeutics
Human Herpesvirus 4
Caspase 3
Reverse Transcription
Cell Proliferation
Polymerase Chain Reaction

Keywords

  • 6-mercaptopurine/azathioprine
  • Crohn's disease
  • Drug resistance
  • Drug transport/uptake
  • Inflammatory bowel disease

ASJC Scopus subject areas

  • Gastroenterology

Cite this

6-mercaptopurine transport in human lymphocytes : Correlation with drug-induced cytotoxicity. / Conklin, Laurie S.; Cuffari, Carmelo; Okazaki, Toshihiko; Miao, Yinglei; Saatian, Bahman; Chen, Tian E.; Tse, Chung Ming; Brant, Steven R.; Li, Xuhang.

In: Journal of Digestive Diseases, Vol. 13, No. 2, 02.2012, p. 82-93.

Research output: Contribution to journalArticle

Conklin, Laurie S. ; Cuffari, Carmelo ; Okazaki, Toshihiko ; Miao, Yinglei ; Saatian, Bahman ; Chen, Tian E. ; Tse, Chung Ming ; Brant, Steven R. ; Li, Xuhang. / 6-mercaptopurine transport in human lymphocytes : Correlation with drug-induced cytotoxicity. In: Journal of Digestive Diseases. 2012 ; Vol. 13, No. 2. pp. 82-93.
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abstract = "Objective: 6-mercaptopurine (6-MP) is efficacious in the treatment of inflammatory bowel disease (IBD). However, about one-third of patients respond poorly to therapy. This study aimed to characterize the inherent differences in 6-MP transport that may cotribute to the differences in treatment responses. METHODS: Intracellular 6-MP accumulation was assayed in Epstein-Barr virus (EBV)-transformed lymphocytes from IBD patients, using 14C-radiolabeled 6-MP. Cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) assay. Apoptosis was assayed based on the activation of caspase 3. The expressions of 15 potential 6-MP transporters were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Intracellular 6-MP accumulation, varying significantly among patients, was carrier-dependent and partially sodium-dependent. 6-MP cytotoxicity was, at least in part, due to apoptosis and correlated with intracellular drug accumulation. The efflux transporters did not appear to contribute to the variability of intracellular drug accumulation between patients, since none correlated with drug accumulation or cytotoxicity. Rather, differential expression of five influx/uptake transporters might be a key contributor to the difference in the accumulation of and susceptibility to the drug. CONCLUSIONS: The heterogeneity of the drug transporters may be the reason for the therapeutic sensitivity of 6-MP in IBD patients. As the 6-MP uptake is a carrier-mediated and partially sodium-dependent process, future studies are necessary to evaluate the role of the putative transporters and their correlation with drug sensitivity in patients.",
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AU - Miao, Yinglei

AU - Saatian, Bahman

AU - Chen, Tian E.

AU - Tse, Chung Ming

AU - Brant, Steven R.

AU - Li, Xuhang

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N2 - Objective: 6-mercaptopurine (6-MP) is efficacious in the treatment of inflammatory bowel disease (IBD). However, about one-third of patients respond poorly to therapy. This study aimed to characterize the inherent differences in 6-MP transport that may cotribute to the differences in treatment responses. METHODS: Intracellular 6-MP accumulation was assayed in Epstein-Barr virus (EBV)-transformed lymphocytes from IBD patients, using 14C-radiolabeled 6-MP. Cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) assay. Apoptosis was assayed based on the activation of caspase 3. The expressions of 15 potential 6-MP transporters were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Intracellular 6-MP accumulation, varying significantly among patients, was carrier-dependent and partially sodium-dependent. 6-MP cytotoxicity was, at least in part, due to apoptosis and correlated with intracellular drug accumulation. The efflux transporters did not appear to contribute to the variability of intracellular drug accumulation between patients, since none correlated with drug accumulation or cytotoxicity. Rather, differential expression of five influx/uptake transporters might be a key contributor to the difference in the accumulation of and susceptibility to the drug. CONCLUSIONS: The heterogeneity of the drug transporters may be the reason for the therapeutic sensitivity of 6-MP in IBD patients. As the 6-MP uptake is a carrier-mediated and partially sodium-dependent process, future studies are necessary to evaluate the role of the putative transporters and their correlation with drug sensitivity in patients.

AB - Objective: 6-mercaptopurine (6-MP) is efficacious in the treatment of inflammatory bowel disease (IBD). However, about one-third of patients respond poorly to therapy. This study aimed to characterize the inherent differences in 6-MP transport that may cotribute to the differences in treatment responses. METHODS: Intracellular 6-MP accumulation was assayed in Epstein-Barr virus (EBV)-transformed lymphocytes from IBD patients, using 14C-radiolabeled 6-MP. Cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) assay. Apoptosis was assayed based on the activation of caspase 3. The expressions of 15 potential 6-MP transporters were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Intracellular 6-MP accumulation, varying significantly among patients, was carrier-dependent and partially sodium-dependent. 6-MP cytotoxicity was, at least in part, due to apoptosis and correlated with intracellular drug accumulation. The efflux transporters did not appear to contribute to the variability of intracellular drug accumulation between patients, since none correlated with drug accumulation or cytotoxicity. Rather, differential expression of five influx/uptake transporters might be a key contributor to the difference in the accumulation of and susceptibility to the drug. CONCLUSIONS: The heterogeneity of the drug transporters may be the reason for the therapeutic sensitivity of 6-MP in IBD patients. As the 6-MP uptake is a carrier-mediated and partially sodium-dependent process, future studies are necessary to evaluate the role of the putative transporters and their correlation with drug sensitivity in patients.

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