Delphinidin attenuates neoplastic transformation in JB6 Cl41 mouse epidermal cells by blocking Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling.
Recent studies suggest that anthocyanidins play a pivotal role in the chemopreventive effects of fruits and vegetables. However, the underlying molecular mechanisms and cellular targets remain unknown. Neoplastic transformation of cells and inflammation are considered to be major events contributing to carcinogenesis. Here, we report that delphinidin, a major dietary anthocyanidin, inhibits tumor promoter-induced transformation and cyclooxygenase-2 (COX-2) expression in JB6 promotion-sensitive mouse skin epidermal (JB6 P+) cells by directly targeting Raf and mitogen-activated protein kinase kinase (MEK). Delphinidin inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced neoplastic transformation and COX-2 expression at both the protein and transcriptional levels. The activation of activator protein-1 and nuclear factor-kappaB induced by TPA was dose dependently inhibited by delphinidin treatment. Delphinidin strongly suppressed Raf1 and MEK1 kinase activities and subsequently attenuated TPA-induced phosphorylation of MEK, extracellular signal-regulated kinase (ERK), p90RSK, and MSK. Although delphinidin suppressed ERK and c-Jun NH(2)-terminal kinase activities, it was more effective at inhibiting Raf1 or MEK1 activities. Pull-down and competition assays revealed that delphinidin binds with Raf1 or MEK1 noncompetitively with ATP. Delphinidin also dose dependently suppressed JB6 P+ cell transformation induced by epidermal growth factor and H-Ras, both of which are involved in the activation of Raf/MEK/ERK signaling. Together, these findings suggested that the targeted inhibition of Raf1 and MEK activities and COX-2 expression by delphinidin contribute to the chemopreventive potential of fruits and vegetables.
Kang
Nam Joo
NJ
Hormel Institute, University of Minnesota, 801 16th Avenue Northeast, Austin, MN 55912, USA.
Lee
Ki Won
KW
Kwon
Jung Yeon
JY
Hwang
Mun Kyung
MK
Rogozin
Evgeny A
EA
Heo
Yong-Seok
YS
Bode
Ann M
AM
Lee
Hyong Joo
HJ
Dong
Zigang
Z
D000818:Animals; D000872:Anthocyanins / Q000494:pharmacology*; D015153:Blotting, Western; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D051546:Cyclooxygenase 2 / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D048490:raf Kinases
D000872:Anthocyanins; D051546:Cyclooxygenase 2; D048490:raf Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C017185:delphinidin