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ISS
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ERK and JNK
signaling pathways are involved in the regulation of activator protein 1 and
cell death elicited by three isothiocyanates in human prostate cancer PC-3
cells.
Carcinogenesis. 2005 Nov 4
Xu C, Shen G, Yuan X, Kim JH, Gopalkrishnan A, Keum YS, Nair S, Kong AN.
Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, The State
University of New Jersey, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA.
Many isothiocyanates (ITCs) such as sulforaphane (SFN), phenethyl
isothiocyanate (PEITC) and allyl isothiocyanate (AITC) are highly effectively in
chemoprevention or reduction of the risk of cancer, and possess antitumor
activities in vitro and in vivo. The activator protein 1 (AP-1) and MAPK
signaling pathways are believed to play an important role in cancer
chemoprevention and chemotherapy due to their involvement in tumor cell growth,
proliferation, apoptosis, and survival. In the present study, we determined the
effects of SFN, PEITC and AITC on AP-1 activation, and investigated the roles of
ERK and JNK signaling pathways in the regulation of AP-1 activation and cell
death elicited by these ITCs in human prostate cancer PC-3 cells. SFN, PEITC and
AITC each induced AP-1 activity potently, and caused a significant elevation in
the phosphorylation of ERK1/2, JNK1/2, Elk-1, and c-Jun. Transfection with ERK2
and upstream kinase DNEE-MEK1 activated AP-1 activity, and transfection with
dominant-negative mutant ERK2 (dnERK2) potently decreased AP-1 activation
induced by SFN, PEITC and AITC. Transfection with JNK1 and upstream kinase MKK7
activated AP-1 activity, and transfection with dominant-negative mutant JNK1-APF
significantly attenuated AP-1 activation induced by SFN, PEITC and AITC.
Pretreatment with MEK1-ERK inhibitor U0126 and JNK inhibitor SP600125
substantially attenuated the decrease in cell viability induced by SFN, PEITC
and AITC. Transfection with dnERK2 and JNK1-APF significantly reversed the
decrease of Bcl-2 expression elicited by these ITCs. Furthermore, transfection
with dnERK2 and JNK1-APF blocked the apoptosis induced by these ITCs in PC-3
cells. Taken together our results indicate that the activation of the ERK and
JNK signaling pathways is important for transcriptional activity of AP-1, and is
involved in the regulation of cell death elicited by ITCs in PC-3 cells.
Note from ISS: Several crucifer sprouts
including broccoli sprouts are currently the most potent natural source of
sulforaphane known. They often produce 10 to 100 times the amount of
sulforaphane as their corresponding mature vegetables.
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