Regulation of Nrf2-and AP-1-mediated gene expression by epigallocatechin-3-gallate and sulforaphane in prostate of Nrf2-knockout or C57BL/6J mice and PC-3 AP-1 human prostate cancer cells

摘要

Aim:To examine the regulatory crosstalk between the transcription factors Nrf2 and AP-1 in prostate cancer(PCa)by dietary cancer chemopreventive compounds(-)epigallocatechin-3-gallate(EGCG)from green tea and sulforaphane(SFN)from cruciferous vegetables.Methods:We performed(i)in vitro studies including luciferase reporter gene assays,MTS cell viability assays,and quantitative realtime PCR(qRT-PCR)in PC-3 AP-1 human PCa cells,(ii)in vivo temporal(3 h and 12 h)microarray studies in the prostate of Nrf2-defi-cient mice that was validated by qRT-PCR,and(iii)in silico bioinformatic analyses to delineate conserved Transcription Factor Binding Sites(TFBS)in the promoter regions of Nrf2 and AP-1,as well as coregulated genes including ATF-2 and ELK-1.Results:Our study shows that AP-1 activation was attenuated by the combinations of SFN(25 μmol/L)and EGCG(20 or 100 μmol/L)in PC-3 cells.Several key Nrf2-dependent genes were down-regulated(3-fold to 35-fold)after in vivo administration of the combination of EGCG(100 mg/kg)and SFN(45 mg/kg).Conserved TFBS signatures were identified in the promoter regions of Nrf2,AP-1,ATF2,and ELK-1 suggesting a potential regulatory mechanism of crosstalk between them.Conclusion:Taken together,our present study of transcriptome profiling the gene expression changes induced by dietary Dhytochemicals SFN and EGCG in Nrf2-deficient mice and in PC-3 cells in vitro demonstrates that the effects of SFN+EGCG could be mediated via concerted modulation of Nrf2 and AP-1 pathways in the prostate.