Acta Pharmacologica Sinica (2010) 31: 1223–1240; doi: 10.1038/aps.2010.147

Acta Pharmacologica Sinica (2010) 31: 1223–1240; doi: 10.1038/aps.2010.147; published online 23 Aug 2010

Original Article

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

Sujit NAIR^{1, 2, 3, 4}, Avantika BARVE¹, Tin-Oo KHOR¹, Guo-xiang SHEN¹, Wen LIN¹, Jefferson Y CHAN⁵, Li CAI⁶, Ah-Ng KONG^{1, *}

¹Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ-08854, USA; ²Division of Molecular Medicine, Amrita Centre for Nanosciences and Molecular Medicine, Amrita Institute of Medical Sciences and Research Centre, Amrita Vishwa Vidyapeetham University, Health Sciences Campus, Kochi-682041, Kerala, India; ³Department of Pharmaceutics, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham University, Health Sciences Campus, Kochi-682041, Kerala, India; ⁴Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham University, Amritapuri Campus, Kollam-690525, Kerala, India; ⁵Department of Pathology, University of California, Irvine, CA-92697, USA; ⁶Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ-08854, USA

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 real-time 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-deficient 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 mmol/L) and EGCG (20 or 100 mmol/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 phytochemicals 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.

Keywords: prostate cancer; sulforaphane; EGCG; Nrf2; AP-1; ATF-2; ELK-1; gene expression profiles

This work was supported in part by RO1-CA118947 and RO1-CA094828 to Ah-Ng Tony Kong, and R21-CA133675 to Li Cai from the National Institutes of Health (NIH).

^*To whom correspondence should be addressed.
E-mail kongt@rci.rutgers.edu
Received 2010-05-30 Accepted 2010-07-22

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