Fustin suppressed melanoma cell growth via cAMP/PKA-dependent mechanism.

Melanoma, a cancer arising from melanocytes, requires a novel treatment strategy because of the ineffectiveness of conventional therapies in certain patients. Fustin is a flavanonol found in young fustic (Cotinus coggygria). However, little is known about its antimelanoma effects. Our study demonstrates that fustin suppresses the growth of B16 melanoma cells. Phalloidin staining of cytoskeletal actin revealed that fustin induced a conformational change in the actin structure of melanoma cells, accompanied by suppressed phosphorylation of myosin regulatory light chain 2 (MLC2), a regulator of actin structure. Furthermore, the protein kinase A (cAMP-dependent protein kinase) inhibitor H89 completely attenuated fustin-induced downregulation of phosphorylated myosin phosphatase targeting subunit 1, which is involved in dephosphorylation of MLC2. In a mouse model, administration of fustin suppressed tumor growth in B16 melanoma cells without adverse effects. In conclusion, our findings suggest that fustin effectively suppresses melanoma cell growth both in vitro and in vivo.

Dextran sulfate sodium-induced mild chronic colitis induced cognitive impairment accompanied by inhibition of neuronal maturation in adolescent mice.

INTRODUCTION: Epidemiological studies indicated that inflammatory bowel disease (IBD), with Crohn's disease and ulcerative colitis as its two main types, is associated with dementia. However, little is known about how adolescents with IBD will affect their cognitive ability as adults. The hippocampus, which is crucial for memory and adult neurogenesis, is closely associated with modulation of cognitive processes. Using a low kDa dextran sulfate sodium (DSS, 5 kDa)-induced chronic colitis (mild chronic colitis) mice model in adolescent mice, we investigated the effects of mild chronic colitis on cognitive functions and hippocampal neurogenesis from adolescent mice to adult mice. METHODS: We induced DSS-induced mild chronic colitis in C57BL/6J male mice by multiple-cycle administration of 1%-2% DSS in autoclaved drinking water. Mice were subjected to novel-object recognition and Y-maze tests. Neurogenesis markers and neuroinflammation-related proteins in the hippocampus of mice were measured. Tight junction proteins in the colon of mice were measured. RESULTS: Mild chronic colitis induced cognitive impairment and decreased adult neurogenesis. Notably, we found a positive correlation with the protein levels between tight junction protein, ZO-1, in the colon and mature neuron marker, NeuN, in the hippocampus. Moreover, mild chronic colitis leads to hippocampal neuroinflammation in adolescent mice. CONCLUSION: Our findings provide new evidence of the association between IBD and dementia risk.

PPAR/PDK4 pathway is involved in the anticancer effects of cGMP in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a type of cancer with a high mortality rate. Current treatments for PDACs often have side effects, and drug resistance in cancer stem cells (CSCs) would be also a problem. Cyclic guanosine monophosphate (cGMP) suppresses the mitochondrial function of PDACs and inhibits their CSC properties. Metabolic regulation plays a crucial role in the maintenance of CSC phenotype, and we hypothesized that cGMP induction suppresses cancer stem cell properties in the cancer cell through energy-related signaling pathways. We demonstrated that induction of cGMP upregulated the PPARα/PDK4 pathway and suppressed CSC properties in PDAC, and patients with pancreatic cancer with high PDK4 gene expression had a better prognosis than those with low gene expression. Therefore, these mechanisms may provide new therapeutic targets for the eradication of pancreatic CSCs.

A gold-complex initiated functionalization of biologically active polyphenols applied to a 18F-labeled chemical probe.

(-)-Epigallocatechin gallate (EGCG), a key component of green tea, exerts therapeutic anticancer and antiallergic properties through its binding to the 67 kDa laminin receptor. The functionalization of EGCG is a promising strategy for creating new drug candidates and chemical probes. In our study, we developed a method for effectively modifying the A ring of EGCG through an electrophilic aromatic substitution with amidomethyl 2-alkynylbenzoates initiated with a gold complex. The 2-alkynylbenzoates treated with (Ph3P)AuOTf under neutral conditions yielded N-acylimines. A further electrophilic aromatic substitution resulted in a mixture of EGCG substituted with acylaminomethyl groups at the 6 and 8 positions with a significant amount noted at the 6 position. We then explored the synthesis of 18F-labeled EGCG with a neopentyl labeling group, an effective labeling group for radiohalogens of not only fluorine-18 but also of astatine-211. To achieve this, we prepared precursors that possessed acid-sensitive protecting groups and base-unstable leaving groups using our established method. Substitution of EGCG with a neopentyl labeling group at either the C6 or C8 position did not affect its anticancer efficacy in U266 cells. Finally, we investigated the preparation of 18F-labeled EGCG. The 18F-fluorination of a mixture of 6- and 8-substituted precursors yielded the corresponding 18F-labeled compounds in 4.5% and 3.0% radiochemical yields (RCYs), respectively. Under acidic conditions, the 18F-labeled 8-substituted compound produced 18F-labeled EGCG in 37% RCY, which heralds the potential of our functionalization approach.

Phosphodiesterase 5 Inhibitor Potentiates Epigallocatechin 3-O-Gallate-Induced Apoptotic Cell Death via Activation of the cGMP Signaling Pathway in Caco-2 Cells.

Epigallocatechin 3-O-gallate (EGCG) is a predominant component in green tea with various health benefits. The 67 kDa laminin receptor (67LR) is a nonintegrin cell surface receptor that is overexpressed in various types of cancer; 67LR was identified a cell surface EGCG target that plays a pivotal role in tumor growth, metastasis, and resistance to chemotherapy. However, the plasma concentration of EGCG is limited, and its molecular mechanisms remain unelucidated in colon cancer. In this study, we found that the phosphodiesterase 5 (PDE5) inhibitor, vardenafil (VDN), potentiates EGCG-induced apoptotic cell death in colon cancer cells. The combination of EGCG and VDN induced apoptosis via activation of the endothelial nitric oxide synthase/cyclic guanosine monophosphate/protein kinase Cδ signaling pathway. In conclusion, the PDE5 inhibitor, VDN, may reduce the intracellular PDE5 enzyme activity that potentiates EGCG-induced apoptotic cell death in Caco-2 cells. These results suggest that PDE5 inhibitors can be used to elevate cGMP levels to induce 67LR-mediated, cancer-specific cell death. Therefore, EGCG may be employed as a therapeutic candidate for colon cancer.

Myricetin improves cognitive function in SAMP8 mice and upregulates brain-derived neurotrophic factor and nerve growth factor.

INTRODUCTION: Considering that neurodegeneration is an irreversible process, an efficient, low-burden approach to prevent dementia is strongly needed. Here, we show that the daily intake of myricetin normalised cognitive dysfunction in senescence-accelerated mouse prone 8 (SAMP8) mice. METHODS: SAMP8 mice were fed a diet supplemented with myricetin and novel object recognition tests and Y-maze tests were performed. Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in brains of SAMP8 mice were measured. The phosphorylation level of cAMP-response-element-binding protein (CREB) level in brains of SAMP8 mice were evaluated. Also, SH-SY5Y cells were treated with myricetin and cAMP levels were measured. RESULTS: In SAMP8 mice, neurotrophins, including BDNF and NGF, were downregulated relative to levels in their normal counterparts. In addition, myricetin intake upregulated the phosphorylation of CREB, the major transcription factor for BDNF and NGF. Also, myricetin induced cAMP upregulation, and CREB phosphorylation via a cAMP-dependent protein kinase-dependent manner in SH-SY5Y cells. CONCLUSION: Taken together, myricetin improves cognitive function in SAMP8 mice and upregulates BDNF and NGF.

Circulating miRNA profiles in mice plasma following flavonoid intake.

BACKGROUND: Polyphenols, including flavonoids, have been the focus of numerous studies that have revealed diverse health benefits. MicroRNAs (miRNAs) constitute a class of small non-coding RNAs that function as posttranscriptional regulators of gene expression. miRNAs can be detected in the blood and these so-called circulating miRNAs are potential biomarkers of various diseases. This study aimed to explore circulating miRNAs in plasma as a means to predict the biological effects of functional food ingredients. METHODS AND RESULTS: We used miRNA microarray analysis to compare plasma miRNA levels in mice orally administered three flavonoids (daidzein, quercetin, and delphinidin). Several miRNAs were differentially expressed in plasma from mice in each treatment group compared with the vehicle-treated group. The plasma levels of miR-25-5p, miR-146b-5p, and miR-501-3p were increased in the flavonoid-treated and the plasma levels of miR-148b-3p, miR-669e-5p, and miR-3962 were decreased. CONCLUSIONS: Our findings suggested that flavonoids alter miRNA expression in plasma and identified promising plasma miRNAs for assessing the functionality of flavonoids.

67-kDa Laminin Receptor-Mediated Cellular Sensing System of Green Tea Polyphenol EGCG and Functional Food Pairing.

The body is equipped with a "food factor-sensing system" that senses food factors, such as polyphenols, sulfur-containing compounds, and vitamins, taken into the body, and plays an essential role in manifesting their physiological effects. For example, (-)-epigallocatechin-3-O-gallate (EGCG), the representative catechin in green tea (Camellia sinensi L.), exerts various effects, including anti-cancer, anti-inflammatory, and anti-allergic effects, when sensed by the cell surficial protein 67-kDa laminin receptor (67LR). Here, we focus on three representative effects of EGCG and provide their specific signaling mechanisms, the 67LR-mediated EGCG-sensing systems. Various components present in foods, such as eriodictyol, hesperetin, sulfide, vitamin A, and fatty acids, have been found to act on the food factor-sensing system and affect the functionality of other foods/food factors, such as green tea extract, EGCG, or its O-methylated derivative at different experimental levels, i.e., in vitro, animal models, and/or clinical trials. These phenomena are observed by increasing or decreasing the activity or expression of EGCG-sensing-related molecules. Such functional interaction between food factors is called "functional food pairing". In this review, we introduce examples of functional food pairings using EGCG.

Eriodictyol-Amplified 67-kDa Laminin Receptor Signaling Potentiates the Antiallergic Effect of O-Methylated Catechin.

(-)-Epigallocatechin-3-O-(3-O-methyl) gallate (1, EGCG3″Me), an antiallergic O-methylated catechin, is present in high quantities in the green tea cultivar "Benifuuki" (Camellia sinensis L.). Previous studies have shown that EGCG3″Me inhibited basophil degranulation mediated through the cell-surface 67-kDa laminin receptor (67LR), but the mechanisms are not fully elucidated. This study aimed to investigate the mechanisms underlying the inhibitory effect of EGCG3″Me on IgE/antigen (Ag)-mediated degranulation and the combined effect of EGCG3″Me with eriodictyol (2), a bioactive flavanone. EGCG3″Me inhibited ß-hexosaminidase release from the rat basophilic/mast cell line RBL-2H3 stimulated by IgE/Ag and induced acid sphingomyelinase (ASM) activity. This induction was inhibited by anti-67LR antibody treatment. The ASM-specific inhibitor desipramine inhibited EGCG3″Me-induced suppression of degranulation. The soluble guanylate cyclase (sGC) inhibitor NS2028 weakened the potency of EGCG3″Me, and the sGC activator BAY41-2272 suppressed degranulation. The ability of EGCG3″Me to induce ASM activity and inhibit degranulation was amplified by eriodictyol. Furthermore, oral administration of the lemon-peel-derived eriodyctiol-7-O-glucoside (3) potentiated the suppressive effect of EGCG3″Me-rich "Benifuuki" green tea on the IgE/Ag-induced passive cutaneous anaphylaxis (PCA) reaction in BALB/c mice. These results suggest that EGCG3″Me inhibits IgE/Ag-mediated degranulation by inducing the 67LR/sGC/ASM signaling pathway, and eriodictyol amplifies this signaling.

Cancer cell selective probe by mimicking EGCG.

Targeting proteins that are overexpressed in cancer cells is the major strategy of molecular imaging and drug delivery systems. The 67-kDa laminin receptor (67LR), also known as oncofetal antigen, is overexpressed in several types of cancer, including melanoma, multiple myeloma, cervical cancer and bile duct carcinoma. 67LR is involved in tumour growth, tumour metastasis and drug resistance. Green tea polyphenol (-)-epigallocatechin-3-O-gallate (EGCG) directly binds to cell-surface 67LR and induces apoptosis through the protein kinase B (Akt)/endothelial nitric oxide synthase/nitric oxide/cyclic GMP (cGMP) axis. Here we report the optimum hydroxyl group for the utilization of EGCG as a novel fluorescent EGCG-mimic imaging probe based on 67LR agonist characters, including Akt activation and inhibitory effect on viable cell number in cancer cells. 67LR specific targeting is unambiguously confirmed with the use of a non-labelled EGCG competitive assay and 67LR knockdown. Importantly, this probe strongly binds to multiple myeloma cells compared with its binding to normal cells.

Src Mediates Epigallocatechin-3-O-Gallate-Elicited Acid Sphingomyelinase Activation.

Epigallocatechin-3-O-gallate (EGCG) is one of the major bioactive compounds known to be present in green tea. We previously reported that EGCG shows selective toxicity through activation of the protein kinase B (Akt)/cyclic guanosine monophosphate (cGMP)/acid sphingomyelinase (ASM) axis via targeting its receptor 67-kDa laminin receptor (67LR), which is overexpressed in cancer. However, little is known about upstream mechanisms of EGCG-elicited ASM activation. In this study we show that the proto-oncogene tyrosine-protein kinase Src, also known as c-src, plays a crucial role in the anticancer effect of EGCG. We showed that EGCG elicits phosphorylation of Src at Tyr 416, a crucial phosphorylation site for its activity, and that the pharmacological inhibition of Src impedes the upstream events in EGCG-induced cell death signaling including upregulation of Akt activity, increase in cGMP levels, and activation of ASM. Moreover, focal adhesion kinase (FAK), which is involved in the phosphorylation of Src, is colocalized with 67LR. EGCG treatment enhanced interaction of FAK and 67LR. Consistent with these findings, pharmacological inhibition of FAK significantly neutralized EGCG-induced upregulation of Akt activity and activation of ASM. Taken together, FAK/Src play crucial roles in the upstream signaling of EGCG.

Epigallocatechin-3-O-gallate induces acid sphingomyelinase activation through activation of phospholipase C.

Epigallocatechin-3-O-gallate (EGCG)-induced cyclic guanosine monophosphate (cGMP) plays a crucial role in EGCG-induced cell death in various types of cancer cells. However, little is known regarding the early molecular events after cGMP induction. In this study, we showed that cGMP induction is sufficient to induce the phosphorylation of protein kinase C delta (PKCδ) at Ser664, the crucial kinase for EGCG-induced activation of acid sphingomyelinase (ASM). Using a chemical inhibitor library, we revealed that the inhibitors of the negative regulators of diacylglycerol strongly increase the effect of EGCG. We also showed that EGCG treatment increased phospholipase C (PLC) activity, and the same results were obtained with cGMP inducer treatment. EGCG-induced ASM activation was completely suppressed by pharmacological inhibition of PLC. Collectively, EGCG-induced cGMP activated the cGMP/PLC/PKCδ/ASM signaling axis in multiple myeloma cells.

Green Tea Polyphenol EGCG Upregulates Tollip Expression by Suppressing Elf-1 Expression.

TLR signaling is critical to innate immune system regulation; however, aberrant TLR signaling is involved in several diseases, including insulin resistance, Alzheimer's disease, and tumor metastasis. Moreover, a recent study found that TLR-4 signaling pathway inhibition might be a target for the suppression of chronic inflammatory disorders. In this article, we show that the green tea polyphenol epigallocatechin-3-O-gallate (EGCG) increases the expression of Toll interacting protein, a strong inhibitor of TLR4 signaling, by suppressing the expression of E74-like ETS transcription factor 1 (Elf-1). A mechanistic study revealed that EGCG suppressed Elf-1 expression via protein phosphatase 2A/cyclic GMP (cGMP)-dependent mechanisms. We also confirmed that orally administered EGCG and a cGMP inducer upregulated Toll interacting protein expression, increased intracellular levels of cGMP in macrophages, and suppressed Elf-1 expression. These data support EGCG and a cGMP inducer as potential candidate suppressors of TLR4 signaling.

Long-term dietary supplementation with the green tea cultivar Sunrouge prevents age-related cognitive decline in the senescence-accelerated mouse Prone8.

A majority of the potential health benefits of green tea, including the potential to prevent cognitive decline, have been attributed to epigallocatechin gallate (EGCG). Sunrouge is a green tea cultivar that contains EGCG and several other bioactive components such as quercetin, myricetin, cyanidin and delphinidin. We compared the effects of Sunrouge and Yabukita, the most popular Japanese green tea cultivar, on cognitive function in the senescence-accelerated mouse Prone8. These mice were fed an experimental diet containing Sunrouge extract (SRE) or Yabukita extract (YBE). SRE feeding significantly prevented cognitive decline, whereas YBE feeding had little effect. Moreover, SRE feeding prevented elevation of the amyloid-ß42 level while improving the gene expression of neprilysin and decreasing beta-site APP-cleaving enzyme 1 in the brain. These preventive effects of SRE against cognitive decline were attributed to the characteristic composition of Sunrouge and strongly suggest that consumption of this cultivar could protect against age-related cognitive decline.

The FOXO3/PGC-1ß signaling axis is essential for cancer stem cell properties of pancreatic ductal adenocarcinoma.

In 95% of patients with pancreatic ductal adenocarcinoma, recurrence is observed following chemotherapy. Findings from several studies have indicated that cancer stem cells (CSCs) are resistant to anticancer agents and may be involved in cancer recurrence and metastasis. The CD44 protein is a major CSC marker, and CD44 also plays an indispensable role in the CSC properties in several cancers, including pancreatic cancer; however, no clinical approach exists to inhibit CD44 activity. Here, we have performed knock-in/knockdown experiments, and we demonstrate that the forkhead box O3 (FOXO3)/liver kinase B1 (LKB1)/AMP-activated protein kinase/peroxisome proliferator-activated receptor-γ co-activator-1ß (PGC-1ß)/pyruvate dehydrogenase-A1 pathway is essential for CD44 expression and CSC properties. We observed that patients exhibiting high pyruvate dehydrogenase-A1 expression have a poor prognosis. Systemic PGC-1ß knock-out mice are fertile and viable and do not exhibit an overt phenotype under normal conditions. This suggests that cGMP induction and PGC-1ß inhibition represent potential strategies for treating patients with pancreatic ductal adenocarcinoma.

Green Tea Polyphenol Epigallocatechin-3-gallate Suppresses Toll-like Receptor 4 Expression via Up-regulation of E3 Ubiquitin-protein Ligase RNF216.

Toll-like receptor 4 (TLR4) plays an essential role in innate immunity through inflammatory cytokine induction. Recent studies demonstrated that the abnormal activation of TLR4 has a pivotal role in obesity-induced inflammation, which is associated with several diseases, including hyperinsulinemia, hypertriglyceridemia, and cardiovascular disease. Here we demonstrate that (-)-epigallocatechin-3-O-gallate, a natural agonist of the 67-kDa laminin receptor (67LR), suppressed TLR4 expression through E3 ubiquitin-protein ring finger protein 216 (RNF216) up-regulation. Our data indicate cyclic GMP mediates 67LR agonist-dependent RNF216 up-regulation. Moreover, we show that the highly absorbent 67LR agonist (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3″Me) significantly attenuated TLR4 expression in the adipose tissue. EGCG3″Me completely inhibited the high-fat/high-sucrose (HF/HS)-induced up-regulation of tumor necrosis factor α in adipose tissue and serum monocyte chemoattractant protein-1 increase. Furthermore, this agonist intake prevented HF/HS-induced hyperinsulinemia and hypertriglyceridemia. Taken together, 67LR presents an attractive target for the relief of obesity-induced inflammation.

A harmonized immunoassay with liquid chromatography-mass spectrometry analysis in egg allergen determination.

Food allergy is a serious health issue worldwide. Implementing allergen labeling regulations is extremely challenging for regulators, food manufacturers, and analytical kit manufacturers. Here we have developed an "amino acid sequence immunoassay" approach to ELISA. The new ELISA comprises of a monoclonal antibody generated via an analyte specific peptide antigen and sodium lauryl sulfate/sulfite solution. This combination enables the antibody to access the epitope site in unfolded analyte protein. The newly developed ELISA recovered 87.1%-106.4% ovalbumin from ovalbumin-incurred model processed foods, thereby demonstrating its applicability as practical egg allergen determination. Furthermore, the comparison of LC-MS/MS and the new ELISA, which targets the amino acid sequence conforming to the LC-MS/MS detection peptide, showed a good agreement. Consequently the harmonization of two methods was demonstrated. The complementary use of the new ELISA and LC-MS analysis can offer a wide range of practical benefits in terms of easiness, cost, accuracy, and efficiency in food allergen analysis. In addition, the new assay is attractive in respect to its easy antigen preparation and predetermined specificity. Graphical abstract The ELISA composing of the monoclonal antibody targeting the amino acid sequence conformed to LC-MS detection peptide, and the protein conformation unfolding reagent was developed. In ovalbumin determination, the developed ELISA showed a good agreement with LC-MS analysis. Consequently the harmonization of immunoassay with LC-MS analysis by using common target amino acid sequence was demonstrated.

A Phytochemical-Sensing Strategy Based on Mass Spectrometry Imaging and Metabolic Profiling for Understanding the Functionality of the Medicinal Herb Green Tea.

Low-molecular-weight phytochemicals have health benefits and reduce the risk of diseases, but the mechanisms underlying their activities have remained elusive because of the lack of a methodology that can easily visualize the exact behavior of such small molecules. Recently, we developed an in situ label-free imaging technique, called mass spectrometry imaging, for visualizing spatially-resolved biotransformations based on simultaneous mapping of the major bioactive green tea polyphenol and its phase II metabolites. In addition, we established a mass spectrometry-based metabolic profiling technique capable of evaluating the bioactivities of diverse green tea extracts, which contain multiple phytochemicals, by focusing on their compositional balances. This methodology allowed us to simultaneously evaluate the relative contributions of the multiple compounds present in a multicomponent system to its bioactivity. This review highlights small molecule-sensing techniques for visualizing the complex behaviors of herbal components and linking such information to an enhanced understanding of the functionalities of multicomponent medicinal herbs.

γ-Tocotrienol upregulates aryl hydrocarbon receptor expression and enhances the anticancer effect of baicalein.

Previous studies have identified biomolecules that mediate the physiological actions of food factors, such as amino acids, vitamins, fatty acids, minerals, plant polyphenols, and lactobacilli, suggesting that our bodies are equipped with an innate system that senses which food factors are required to maintain our health. However, the effects of environmental factors on food factor sensing (FFS) remains largely unknown. Tocotorienols (T3s), which belongs to the vitamin E family, possess several physiological functions, including cholesterol lowering and neuroprotective effects. Here, we investigated the effects of naturally abundant γ-T3 on FFS-related gene expressions in melanoma using a DNA chip. Our results showed that γ-T3 increased the expression level of aryl hydrocarbon receptor (AhR), a sensing molecule to plant polyphenol baicalein. The co-treatment with γ-T3 and baicalein enhanced the anti-proliferative activity of baicalein, accompanied by the downstream events of AhR-activation induced by baicalein. These data suggest that γ-T3 upregulates AhR expression and enhances its sensitivity to baicalein.

The Synthesis of trans-Flavan-3-ol Gallates by Regioselective Oxidative Etherification and Their Cytotoxicity Mediated by 67 LR.

We report on a chiral pool approach for the synthesis of trans-flavan-3-ol gallates from epichlorohydrin. The trans-flavan-3-ol gallates were prepared by the cycloetherification of the phenol at the C2 benzylic position of 2-acylozyl-1,3-diarylpropane during regioselective C-H oxidation. The 1,3-diarylpropanes were prepared starting from epichlorohydrin by epoxide opening with A and B ring precursors, followed by acylation of the resultant alcohol with galloyl chloride. The availability of both the enantiomers of epichlorohydrin allowed the preparation of the corresponding enantiomer using the same procedure. The cytotoxicity of the compounds against U266 cells was tested, in which 5-deoxy-7,3'-O-dimethyl gallocatechin gallate exhibited cytotoxicity that was more than ten times stronger than natural (-)-EGCG. In addition, the absolute configuration of the derivatives did not critically affect the biological activity.