[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) are non-coding RNAs involved in various biological processes by regulating their target genes. Green tea polyphenol (−)-epigallocatechin-3-O-gallate (EGCG) inhibits melanoma tumor growth by activating 67-kDa laminin receptor (67LR) signaling. To examine the effect of EGCG on miRNA expression in melanoma cells, we performed miRNA microarray analysis. We showed that EGCG up-regulated miRNA-let-7b expression through 67LR in melanoma cells. The EGCG-induced up-regulation of let-7b led to down-regulation of high mobility group A2 (HMGA2), a target gene related to tumor progression. 67LR-dependent cAMP/protein kinase A (PKA)/protein phosphatase 2A (PP2A) signaling pathway activation was involved in the up-regulation of let-7b expression induced by EGCG. These findings provide a basis for understanding the mechanism of miRNA regulation by EGCG.
[Show abstract][Hide abstract] ABSTRACT: Tea (Camellia sinensis L.) is a popular beverage worldwide, and because of its possible health effects, it has received considerable attention as a medicinal herb. Unfermented green tea constituents show various biological and pharmacological activities. Recently, metabolomic approaches to study the functionality and quality of tea are becoming more common place. One such metabolomic approach, metabolic profiling, can provide information on the relationships between the metabolome and factors such as phenotype or quality. Mass spectrometry (MS) and proton nuclear magnetic resonance (1H-NMR) spectroscopy combined with multivariate statistical analyses are employed for tea metabolomic studies. The highlighted topics are divided into three sections: (1) tea chemical composition, (2) metabolic responses to tea consumption, and (3) biotransformation of dietary tea components. In this chapter, we describe the latest metabolomic techniques applicable to new avenues of tea research.
[Show abstract][Hide abstract] ABSTRACT: An epidemiological study showed that green tea consumption is associated with a reduced risk of hematopoietic malignancy. The major green tea polyphenol epigallocatechin‑3-O-gallate (EGCG) is reported to have anticancer effects. Chronic myeloid leukemia (CML) is a major hematopoietic malignancy characterized by expansion of myeloid cells. In the present study, we showed EGCG-induced acid sphingomyelinase (ASM) activation and lipid raft clustering in CML cells. The ASM inhibitor desipramine significantly reduced EGCG-induced cell death. Protein kinase Cδ is a well‑known kinase that plays an important role in ASM activation. We observed EGCG-induced phosphorylation of protein kinase Cδ at Ser664. Importantly, EGCG-induced ASM activation was significantly reduced by pretreatment of CML cells with the soluble guanylate cyclase inhibitor NS2028, suggesting that EGCG induced ASM activation through the cyclic guanosine monophosphate (cGMP)-dependent pathway. Indeed, pharmacological inhibition of a cGMP-negative regulator enhanced the anti-CML effect of EGCG. These results indicate that EGCG-induced cell death via the cGMP/ASM pathway in CML cells.
[Show abstract][Hide abstract] ABSTRACT: Green tea extract (GTE) induces apoptosis of cancer cells without adversely affecting normal cells. Several clinical trials reported that GTE was well tolerated and had potential anti-cancer efficacy. Epigallocatechin-3-O-gallate (EGCG) is the primary compound responsible for the anti-cancer effect of GTE; however, the effect of EGCG alone is limited. To identify GTE compounds capable of potentiating EGCG bioactivity, we performed metabolic profiling of 43 green tea cultivar panels by liquid chromatography-mass spectrometry (LC-MS). Here, we revealed the polyphenol eriodictyol significantly potentiated apoptosis induction by EGCG in vitro and in a mouse tumour model by amplifying EGCG-induced activation of the 67-kDa laminin receptor (67LR)/protein kinase B/endothelial nitric oxide synthase/protein kinase C delta/acid sphingomyelinase signalling pathway. Our results show that metabolic profiling is an effective chemical-mining approach for identifying botanical drugs with therapeutic potential against multiple myeloma. Metabolic profiling-based data mining could be an efficient strategy for screening additional bioactive compounds and identifying effective chemical combinations.
Full-text · Article · Mar 2015 · Scientific Reports
[Show abstract][Hide abstract] ABSTRACT: We studied the nutritional components and functional activities of 6 parts (flower bud, stem, lower main stalk, leaf stalk, leaf, root) of raw whole broccoli (Brassica oleracea var. Italica). Flower buds showed the highest levels of vitamin C (188.2 mg/100 g) and S-methylmethionine (16.7 mg/100 g). The buds contained 64.9 mg/100 g of polyphenols. Moreover, they exhibited the highest histamine release inhibitory activity. The vitamin C, S-methylmethionine and polyphenol contents of the leaves were 18%, 29% and 3.1 times those of flower buds, respectively. The leaves showed histamine release inhibitory activity and leukotriene release inhibitory activity. Additionally, the leaves tended to decrease IgE production. The leaves also showed anti-allergic activity as compared with flower buds. The vitamin C, S-methylmethionine and polyphenol contents of the roots were 13%, 25% and 83% of those of flower buds, respectively. Notably, aqueous extracts of roots produced the highest proliferative arrest in MCF-7 human breast cancer cells. These results suggest that useful components exist not only in the edible flower buds but in all parts of broccoli.
No preview · Article · Jan 2015 · Nippon Shokuhin Kagaku Kogaku Kaishi
[Show abstract][Hide abstract] ABSTRACT: The Ras/Raf/MEK/ERK pathway has been identified as a major, druggable regulator of melanoma. Mutational activation of BRAF is the most prevalent genetic alteration in human melanoma, resulting in constitutive melanoma hyperproliferation. A selective
BRAF inhibitor showed remarkable clinical activity in patients with mutated BRAF. Unfortunately, most patients acquire resistance to the BRAF inhibitor, highlighting the urgent need for new melanoma treatment strategies. Green tea polyphenol (−)-epigallocatechin-3-O-gallate (EGCG) inhibits cell proliferation independently of BRAF inhibitor sensitivity, suggesting that increased understanding of the anti-melanoma activity of EGCG may provide a novel
therapeutic target. Here, by performing functional genetic screening, we identified protein phosphatase 2A (PP2A) as a critical
factor in the suppression of melanoma cell proliferation. We demonstrated that tumor-overexpressed 67-kDa laminin receptor
(67LR) activates PP2A through adenylate cyclase/cAMP pathway eliciting inhibitions of oncoproteins and activation of tumor
suppressor Merlin. Activating 67LR/PP2A pathway leading to melanoma-specific mTOR inhibition shows strong synergy with the
BRAF inhibitor PLX4720 in the drug-resistant melanoma. Moreover, SET, a potent inhibitor of PP2A, is overexpressed on malignant
melanoma. Silencing of SET enhances 67LR/PP2A signaling. Collectively, activation of 67LR/PP2A signaling may thus be a novel
rational strategy for melanoma-specific treatment.
No preview · Article · Oct 2014 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: In this study, we revealed that a Mekabu (Udaria pinnantifida) extract enhanced immunoglobulin (Ig) production of mouse spleen lymphocytes. Furthermore, it was suggested that water-soluble and high molecular weight ingredients in the Mekabu extract have significant enhancing effect on Ig production. Therefore, fucoidan was estimated as the active component.
No preview · Article · Oct 2014 · Bioscience Biotechnology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) is a powerful technique for visualizing the distribution of a wide range of biomolecules within tissue sections. However, methodology for visualizing a bioactive ellagitannin has not yet been established. Here, we present a novel in situ label-free MALDI-MSI technique for visualizing the distribution of strictinin, a bioactive ellagitannin found in green tea, within mammalian kidney after oral dosing. Among nine representative matrix candidates, we found that 1,5-diaminonaphthalene (1,5-DAN), harmane and ferulic acid showed higher sensitivity to strictinin spotted onto a MALDI sample plate. Of these, 1,5-DAN enables visualization of a two-dimensional image of strictinin directly spotted on mouse kidney sections with the highest sensitivity. Furthermore, 1,5-DAN-based MALDI-MSI could detect the unique distribution of orally dosed strictinin within kidney sections. This in situ label-free imaging technique will contribute to the localization analysis of strictinin and its biological mechanisms.
Full-text · Article · Sep 2014 · Journal of Agricultural and Food Chemistry
[Show abstract][Hide abstract] ABSTRACT: Strictinin has been shown to suppress interleukin (IL)-4-induced signal transducer and activator of transcription (STAT)-6 phosphorylation, which is a critical event for IgE class switching. However, it is unclear how strictinin inhibits STAT6 activation. Strictinin inhibited STAT6 phosphorylation by suppressing IL-4 receptor α (IL-4Rα) activation. Strictinin was bound to the cell surface and only localized in non-lipid raft fraction of the cells where IL-4Rα was also located. In addition, strictinin directly bound to IL-4Rα and inhibited binding of IL-4 to IL-4Rα. These results suggest that IL-4Rα locating in non-lipid raft region is a target molecule for stirctinin in inhibiting STAT6 activation.
Full-text · Article · Jun 2014 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Interleukin (IL)-4 is a critical stimulator that induces ɛ germline transcripts (ɛGT) for switch recombination to initiate immunoglobulin (Ig) E and is important in allergic disease pathogenesis. We found pentagalloylglucose (PGG) inhibited IL-4-induced ɛGT expression. PGG exerted its inhibitory function by suppressing IL-4-induced activation of IL-4Rα, JAK3 and STAT6. Furthermore, tannic acid, a higher galloylated PGG, attenuated ovalbumin-induced IgE production in vivo by inhibiting IL-4-induced ɛGT expression and the IL-4 signaling pathway. In conclusion, our results suggest that tannic acid may attenuate allergic diseases by suppressing IgE production by inhibiting IL-4-induced signaling.
[Show abstract][Hide abstract] ABSTRACT: We examined the anti-allergic effect of strawberry extract on human peripheral blood mononuclear cells (PBMCs) and atopic dermatitis model mice NC/NgaTndCrlj. The addition of strawberry extract suppressed total IgE production in the cedar pollen antigen Cry j 1-stimulated PBMCs. Flow cytometric analysis showed that strawberry extract decreased the rate of CD3(+)CD4(+) helper T cells by 17.3% and increased the rate of CD3(+)CD8(+) cytotoxic T cells by 19.7% in PBMCs. Moreover, the extract inhibited the expression level of GATA3 that is the master regulator of type 2 helper T cells (Th2) in human primary pan T cells isolated from PBMCs. Oral administration of strawberry extract lowered dermatitis scores and serum IgE levels in mice. In addition, it also decreased the GATA3 expression level in mouse blood cells. These results revealed that strawberry extract suppressed the severity of atopic dermatitis through the down-regulation of serum IgE by inhibition of Th2 differentiation.
No preview · Article · Oct 2013 · Journal of Functional Foods
[Show abstract][Hide abstract] ABSTRACT: Although understanding the high-resolution spatial distribution of bioactive small molecules is indispensable for elucidating their biological or pharmacological effects, there has been no analytical technique that can easily detect the naïve molecular localization in mammalian tissues. We herein present a novel in situ label-free imaging technique for visualizing bioactive small molecules, using a polyphenol. We established a 1,5-diaminonaphthalene (1,5-DAN)-based matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) technique for visualizing epigallocatechin-3-O-gallate (EGCG), the major bioactive green tea polyphenol, within mammalian tissue micro-regions after oral dosing. Furthermore, the combination of this label-free MALDI-MSI method and a standard-independent metabolite identification method, an isotopic fine structure analysis using ultrahigh-resolution mass spectrometer, allows for the visualization of spatially-resolved biotransformation based on simultaneous mapping of EGCG and its phase II metabolites. Although this approach has limitations of the detection sensitivity, it will overcome the drawbacks associated with conventional molecular imaging techniques, and could contribute to biological discovery.
[Show abstract][Hide abstract] ABSTRACT: We investigated the effects of extracts of Benifuuki (a tea cultivar that contains methylated catechins such as epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me)) in mice fed a high-fat/high-sucrose (HF/HS) diet. This tea cultivar was then compared with an extract of Yabukita (a popular tea cultivar that lacks methylated catechins). For 6 weeks, C57BL/6J mice were fed either HF/HS diet with or without tea extracts from tea cultivars, which contained almost identical ingredients except for methylated catechins (i.e., Yabukita (0.2% and 1%) or Benifuuki (0.2% and 1%) extract powders). Supplementation with Benifuuki 0.2% markedly lowered plasma levels of TG and NEFAs compared with mice supplemented with Yabukita 0.2%. The diet containing Benifuuki 1% decreased adipose tissue weights, liver TG, and expression of lipogenic genes in the liver. These results suggested that Benifuuki had much greater lipid-lowering effects than Yabukita. Taken together, these data suggest that methylated catechins direct the strong lipid-lowering activity of Benifuuki.
[Show abstract][Hide abstract] ABSTRACT: (-)-Epigallocatechin-3-O-gallate (EGCG), a polyphenol in green tea, induces apoptosis in acute myeloid leukemia (AML) cells without affecting normal cells. In this study, we observed that cGMP acts as a cell death mediator of the EGCG-induced anti-AML effect through acid sphingomyelinase activation. EGCG activated the Akt/eNOS axis, a well-known mechanism in vascular cGMP upregulation. We also observed that a major cGMP negative regulator, phosphodiesterase 5, was overexpressed in AML cells, and PDE5 inhibitor, an anti-erectile dysfunction drug, synergistically enhanced the anti-AML effect of EGCG. This combination regimen killed AML cells via overexpressed 67-kDa laminin receptors.