A soybean Kunitz trypsin inhibitor reduces tumor necrosis factor-alpha production in ultraviolet-exposed primary human keratinocytes.
BACKGROUND
Cytokines are produced as a consequence of photo-damaged DNA and oxidative stress in ultraviolet (UV)-exposed keratinocytes. A soybean Kunitz trypsin inhibitor (KTI) down-regulates the expression of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) in tumor cells and inflammatory cells.


OBJECTIVE
The effect of KTI on TNF-alpha production in UV-exposed primary human keratinocytes was analyzed.


RESULTS
We show (i) UV induced up-regulation of TNF-alpha mRNA and protein expression in keratinocytes; (ii) cells treated with KTI before UV irradiation showed a significantly lower accumulation of TNF-alpha protein in a dose-dependent manner and a reduced UV-induced up-regulation of TNF-alpha mRNA expression; (iii) KTI inhibited the induction of TNF-alpha target molecules interleukin-1beta (IL-1beta) and IL-6 proteins; (iv) UV irradiation transiently activated c-Jun N-terminal kinase (JNK) and Akt signaling but only weakly activated extracellular signal-regulated kinase (ERK) and p38; (v) KTI specifically inhibited UV-induced activation of ERK, JNK, and p38, but not Akt; (vi) treatment of cells with SP600125, a pharmacological inhibitor of JNK, predominantly suppressed UV-induced up-regulation of TNF-alpha expression; and (vii) KTI did not enhance suppression of UV-induced JNK phosphorylation by SP600125.


CONCLUSIONS
KTI specifically inhibited UV-induced up-regulation of cytokine expression predominantly through suppression of JNK signaling pathway.
Kobayashi
Hiroshi
H
Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Handayama, Hamamatsu, Shizuoka, Japan.
Yoshida
Ryuji
R
Kanada
Yasufumi
Y
Fukuda
Yoichi
Y
Yagyu
Tatsuo
T
Inagaki
Kiyokazu
K
Kondo
Toshiharu
T
Kurita
Noriyuki
N
Yamada
Yoshihiko
Y
Sado
Toshiyuki
T
Kitanaka
Takashi
T
Suzuki
Mika
M
Kanayama
Naohiro
N
Terao
Toshihiko
T
D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism; D014466:Ultraviolet Rays
D016207:Cytokines; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D014360:Trypsin Inhibitor, Kunitz Soybean; D007770:L-Lactate Dehydrogenase; D020929:Mitogen-Activated Protein Kinase Kinases