Structural influence of isothiocyanates on the antioxidant response element (ARE)-mediated heme oxygenase-1 (HO-1) expression

Auemduan Prawan, Young Sam Keum, Tin Oo Khor, Siwang Yu, Sujit Nair, Wenge Li, Longqin Hu, Ah Ng Tony Kong

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Purpose. Isothiocyanates (ITCs), existing abundantly in cruciferous vegetables, is one class of promising dietary cancer chemopreventive agents that possess strong cancer protective effects by modulation of phase II detoxifying/antioxidant enzyme activities. However, limited studies regarding to the structure-activity relationship (SAR) of ITCs on the induction of phase II detoxifying/antioxidant enzymes are reported. In this study, the effects of ten structurally related isothiocyanates on the antioxidant response element (ARE)-mediated antioxidant enzyme heme oxygenase-1 (HO-1) induction in human hepatoma HepG2-C8 cells were evaluated. Materials and Methods. After exposure of HepG2-C8 cells to ITCs, cell viability, luciferase reporter assay, Western blot analysis and quantitative real-time PCR were conducted. Results. Treatments with most ITCs significantly activated ARE-mediated luciferase activity with different maximal degree of ARE induction. In addition, ITCs caused a substantial induction of HO-1 protein, which was closely correlated with inductive level of Nrf2 protein. Real-time PCR revealed that the expression of HO-1 mRNA and protein was significantly increased after treatments with ITCs, although not directly correlated. HO-1 induction by ITCs was attenuated in HepG2-C8 cells transiently transfected with a dominant negative mutant of Nrf2 (Nrf2-M4), whereas it was totally absent in Nrf2 -/- mouse embryonic fibroblasts. In addition, ARE activation by ITCs was associated with the depletion of intracellular glutathione. Conclusion. Collectively, our results demonstrate that the ITC class of compounds activates ARE-mediated HO-1 gene transcription through Nrf2/ARE signaling pathway, however, their inductive effects are quite specific, depending on the chemical structure. These results suggest the possibility that some synthetic ITCs might have superior chemopreventive activity than natural ITCs.

Original languageEnglish (US)
Pages (from-to)836-844
Number of pages9
JournalPharmaceutical Research
Volume25
Issue number4
DOIs
StatePublished - Apr 2008
Externally publishedYes

Fingerprint

Antioxidant Response Elements
Isothiocyanates
Heme Oxygenase-1
Hep G2 Cells
Antioxidants
Luciferases
Real-Time Polymerase Chain Reaction
Enzymes
Proteins
Vegetables
Enzyme activity
Transcription
Fibroblasts
Structure-Activity Relationship
Glutathione

Keywords

  • Heme oxygenase-1 (HO-1)
  • Isothiocyanates (ITCs)
  • Nrf2
  • Phase II drug metabolism
  • Structure-activity relationship

ASJC Scopus subject areas

  • Chemistry(all)
  • Pharmaceutical Science
  • Pharmacology

Cite this

Structural influence of isothiocyanates on the antioxidant response element (ARE)-mediated heme oxygenase-1 (HO-1) expression. / Prawan, Auemduan; Keum, Young Sam; Khor, Tin Oo; Yu, Siwang; Nair, Sujit; Li, Wenge; Hu, Longqin; Kong, Ah Ng Tony.

In: Pharmaceutical Research, Vol. 25, No. 4, 04.2008, p. 836-844.

Research output: Contribution to journalArticle

Prawan, Auemduan ; Keum, Young Sam ; Khor, Tin Oo ; Yu, Siwang ; Nair, Sujit ; Li, Wenge ; Hu, Longqin ; Kong, Ah Ng Tony. / Structural influence of isothiocyanates on the antioxidant response element (ARE)-mediated heme oxygenase-1 (HO-1) expression. In: Pharmaceutical Research. 2008 ; Vol. 25, No. 4. pp. 836-844.
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abstract = "Purpose. Isothiocyanates (ITCs), existing abundantly in cruciferous vegetables, is one class of promising dietary cancer chemopreventive agents that possess strong cancer protective effects by modulation of phase II detoxifying/antioxidant enzyme activities. However, limited studies regarding to the structure-activity relationship (SAR) of ITCs on the induction of phase II detoxifying/antioxidant enzymes are reported. In this study, the effects of ten structurally related isothiocyanates on the antioxidant response element (ARE)-mediated antioxidant enzyme heme oxygenase-1 (HO-1) induction in human hepatoma HepG2-C8 cells were evaluated. Materials and Methods. After exposure of HepG2-C8 cells to ITCs, cell viability, luciferase reporter assay, Western blot analysis and quantitative real-time PCR were conducted. Results. Treatments with most ITCs significantly activated ARE-mediated luciferase activity with different maximal degree of ARE induction. In addition, ITCs caused a substantial induction of HO-1 protein, which was closely correlated with inductive level of Nrf2 protein. Real-time PCR revealed that the expression of HO-1 mRNA and protein was significantly increased after treatments with ITCs, although not directly correlated. HO-1 induction by ITCs was attenuated in HepG2-C8 cells transiently transfected with a dominant negative mutant of Nrf2 (Nrf2-M4), whereas it was totally absent in Nrf2 -/- mouse embryonic fibroblasts. In addition, ARE activation by ITCs was associated with the depletion of intracellular glutathione. Conclusion. Collectively, our results demonstrate that the ITC class of compounds activates ARE-mediated HO-1 gene transcription through Nrf2/ARE signaling pathway, however, their inductive effects are quite specific, depending on the chemical structure. These results suggest the possibility that some synthetic ITCs might have superior chemopreventive activity than natural ITCs.",
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T1 - Structural influence of isothiocyanates on the antioxidant response element (ARE)-mediated heme oxygenase-1 (HO-1) expression

AU - Prawan, Auemduan

AU - Keum, Young Sam

AU - Khor, Tin Oo

AU - Yu, Siwang

AU - Nair, Sujit

AU - Li, Wenge

AU - Hu, Longqin

AU - Kong, Ah Ng Tony

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AB - Purpose. Isothiocyanates (ITCs), existing abundantly in cruciferous vegetables, is one class of promising dietary cancer chemopreventive agents that possess strong cancer protective effects by modulation of phase II detoxifying/antioxidant enzyme activities. However, limited studies regarding to the structure-activity relationship (SAR) of ITCs on the induction of phase II detoxifying/antioxidant enzymes are reported. In this study, the effects of ten structurally related isothiocyanates on the antioxidant response element (ARE)-mediated antioxidant enzyme heme oxygenase-1 (HO-1) induction in human hepatoma HepG2-C8 cells were evaluated. Materials and Methods. After exposure of HepG2-C8 cells to ITCs, cell viability, luciferase reporter assay, Western blot analysis and quantitative real-time PCR were conducted. Results. Treatments with most ITCs significantly activated ARE-mediated luciferase activity with different maximal degree of ARE induction. In addition, ITCs caused a substantial induction of HO-1 protein, which was closely correlated with inductive level of Nrf2 protein. Real-time PCR revealed that the expression of HO-1 mRNA and protein was significantly increased after treatments with ITCs, although not directly correlated. HO-1 induction by ITCs was attenuated in HepG2-C8 cells transiently transfected with a dominant negative mutant of Nrf2 (Nrf2-M4), whereas it was totally absent in Nrf2 -/- mouse embryonic fibroblasts. In addition, ARE activation by ITCs was associated with the depletion of intracellular glutathione. Conclusion. Collectively, our results demonstrate that the ITC class of compounds activates ARE-mediated HO-1 gene transcription through Nrf2/ARE signaling pathway, however, their inductive effects are quite specific, depending on the chemical structure. These results suggest the possibility that some synthetic ITCs might have superior chemopreventive activity than natural ITCs.

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KW - Phase II drug metabolism

KW - Structure-activity relationship

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