TY - JOUR
T1 - Induction of quinone oxidoreductase 1 enzyme by Rhazya stricta through Nrf2-dependent mechanism
AU - El Gendy, Mohamed A.M.
AU - Ali, Badreldin H.
AU - Michail, Karim
AU - Siraki, Arno G.
AU - El-Kadi, Ayman O.S.
N1 - Funding Information:
This work was supported by the Natural Sciences and Engineering Council of Canada (NSERC) Grant RGPIN 250139 to A.O.S.E., M.A.M.E. is the recipient of the Egyptian government scholarship and the Dissertation Fellowship, University of Alberta. We are grateful to Dr. Vishwa Somayaji and Dr. Khaled Abdellatif for their help in the Mass spectrometry.
PY - 2012/11/21
Y1 - 2012/11/21
N2 - Ethnopharmacological relevance: Rhazya stricta Decne. (Apocynaceae) is a common medicinal plant in the Arabian Peninsula, Pakistan and India. Rhazya stricta has been used traditionally to treat several diseases including tumors; however, the underlying mechanism is still not fully elucidated. Aim of the study: The aim of this study is to examine the ability of Rhazya stricta to induce a key enzyme involved in cancer chemoprevention, NAD(P)H:quinone oxidoreductase 1 (Nqo1) in murine and human hepatoma cells. Nqo1 is regulated by the nuclear factor erythroid 2-related factor 2 (Nrf2) and the aryl hydrocarbon receptor (AhR) transcription factors. Materials and methods: Rhazya stricta leaves were extracted using ethanol, the strong basic alkaloid fraction (AF) was isolated according to a bioassay-guided fractionation and its mass spectrum was used as a fingerprint for its identity. The effect of increasing concentrations of AF on Nqo1 was tested in murine hepatoma Hepa 1c1c7 and human HepG2 cells. The role of Nrf2-dependent mechanism was tested by using Nrf2-dependent luciferase assay and by determining the Nrf2 nuclear accumulation in Hepa 1c1c7 cells. The role of AhR-dependent mechanism was assessed by using an AhR-deficient version of murine hepatoma c12 cells. Results: AF significantly induced the Nqo1 at mRNA, protein and catalytic activity levels in murine hepatoma Hepa 1c1c7 cells. Moreover, the induction of Nqo1 by AF was completely abolished by using the transcriptional inhibitor, actinomycin D, implying a role of transcriptional regulation. In addition, the role of Nrf2 signaling pathway was confirmed by the induction of Nrf2-dependent luciferase activity and the induced Nrf2 nuclear accumulation in Hepa 1c1c7 cells. Interestingly, AF induced Nqo1 at mRNA and catalytic activity in c12 and HepG2 cells. Finally, the AF induced the Nrf2-dependent luciferase activity in HepG2 cells, confirming the role of Nrf2 in its regulation. Conclusions: The present study presents the first evidence that Rhazya stricta and its active strongly basic alkaloid fraction induce the chemopreventative enzyme, Nqo1 through Nrf2-dependent mechanism.
AB - Ethnopharmacological relevance: Rhazya stricta Decne. (Apocynaceae) is a common medicinal plant in the Arabian Peninsula, Pakistan and India. Rhazya stricta has been used traditionally to treat several diseases including tumors; however, the underlying mechanism is still not fully elucidated. Aim of the study: The aim of this study is to examine the ability of Rhazya stricta to induce a key enzyme involved in cancer chemoprevention, NAD(P)H:quinone oxidoreductase 1 (Nqo1) in murine and human hepatoma cells. Nqo1 is regulated by the nuclear factor erythroid 2-related factor 2 (Nrf2) and the aryl hydrocarbon receptor (AhR) transcription factors. Materials and methods: Rhazya stricta leaves were extracted using ethanol, the strong basic alkaloid fraction (AF) was isolated according to a bioassay-guided fractionation and its mass spectrum was used as a fingerprint for its identity. The effect of increasing concentrations of AF on Nqo1 was tested in murine hepatoma Hepa 1c1c7 and human HepG2 cells. The role of Nrf2-dependent mechanism was tested by using Nrf2-dependent luciferase assay and by determining the Nrf2 nuclear accumulation in Hepa 1c1c7 cells. The role of AhR-dependent mechanism was assessed by using an AhR-deficient version of murine hepatoma c12 cells. Results: AF significantly induced the Nqo1 at mRNA, protein and catalytic activity levels in murine hepatoma Hepa 1c1c7 cells. Moreover, the induction of Nqo1 by AF was completely abolished by using the transcriptional inhibitor, actinomycin D, implying a role of transcriptional regulation. In addition, the role of Nrf2 signaling pathway was confirmed by the induction of Nrf2-dependent luciferase activity and the induced Nrf2 nuclear accumulation in Hepa 1c1c7 cells. Interestingly, AF induced Nqo1 at mRNA and catalytic activity in c12 and HepG2 cells. Finally, the AF induced the Nrf2-dependent luciferase activity in HepG2 cells, confirming the role of Nrf2 in its regulation. Conclusions: The present study presents the first evidence that Rhazya stricta and its active strongly basic alkaloid fraction induce the chemopreventative enzyme, Nqo1 through Nrf2-dependent mechanism.
KW - Chemoprevention
KW - Nqo1
KW - Nuclear factor erythroid 2-related factor 2
KW - Rhazya stricta
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U2 - 10.1016/j.jep.2012.09.032
DO - 10.1016/j.jep.2012.09.032
M3 - Article
C2 - 23026305
AN - SCOPUS:84868212358
SN - 0378-8741
VL - 144
SP - 416
EP - 424
JO - Journal of Ethnopharmacology
JF - Journal of Ethnopharmacology
IS - 2
ER -
