Inhibitory effect of citrus 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone on 12-O-tetradecanoylphorbol 13-acetate-induced skin inflammation and tumor promotion in mice

Ching-Shu Lai, Shiming Li, Chee-Yin Chai, Chih-Yu Lo, Chi-Tang Ho, Ying-Jan Wang, Min-Hsiung Pan
Carcinogenesis 2007, 28 (12): 2581-8
5-Hydroxy-3,6,7,8,3',4'-hexamethoxyflavone (5-OH-HxMF), a polymethoxyflavone, is found exclusively in the Citrus genus, particularly in the peels of sweet orange. Herein, we report the first investigation of the inhibitory effects of 5-OH-HxMF on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in mouse skin. We found that the topical application of 5-OH-HxMF can effectively inhibit the transcriptional activation of iNOS and COX-2 mRNA and protein in mouse skin stimulated by TPA. Pre-treatment with 5-OH-HxMF resulted in the reduction of TPA-induced nuclear translocation of nuclear factor-kappaB (NF-kappaB) subunit and DNA binding by blocking phosphorylation of inhibitor kappaB (IkappaB) alpha and p65 and subsequent degradation of IkappaBalpha. In addition, 5-OH-HxMF can inhibit TPA-induced phosphorylation and nuclear translocation of the signal transducer and activator of transcription-3. Moreover, 5-OH-HxMF can suppress TPA-induced activation of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt, which are upstream of NF-kappaB. We also found that 5-OH-HxMF significantly inhibited TPA-induced mouse skin inflammation by decreasing inflammatory parameters. Furthermore, 5-OH-HxMF significantly inhibited 7,12-dimethylbenz[a]anthracene/TPA-induced skin tumor formation by reducing the tumor incidence and tumor multiplicity of papillomas at 20 weeks. Therefore, all these results revealed for the first time that 5-OH-HxMF is an effective antitumor agent and its inhibitory effect is through the down-regulation of inflammatory iNOS and COX-2 gene expression in mouse skin, suggesting that 5-OH-HxMF is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"