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Although specific compounds found in some East Asian traditional medicines have been shown to exhibit bioactive properties, their molecular mechanisms of action remain elusive. The bark of the Alnus species has been used for the treatment of various pathological conditions including hemorrhage, alcoholism, fever, diarrhea, skin diseases, inflammation, and cancer in East Asia for centuries. In this study, we show that hirsutenone, a bioactive compound in Alnus japonica, exhibits anti-cancer effects against prostate cancer through a direct physical inhibition of Akt1/2. Hirsutenone suppressed anchorage-dependent and independent cell growth of PC3 and LNCaP human prostate cancer cells. Annexin V and Propidium iodide (PI) staining results demonstrated that hirsutenone strongly induces apoptotic cell death in both PC3 and LNCaP cells. Furthermore, treatment of hirsutenone attenuated phosphorylation of mammalian target of rapamycin (mTOR), a downstream substrate of Akt, without affecting Akt phosphorylation. Kinase and pull-down assay results clearly show that hirsutenone inhibits Akt1 and 2 by direct binding in an adenosine triphosphate (ATP)-noncompetitive manner in vitro and ex vivo. Our results show that hirsutenone suppresses human prostate cancer by targeting Akt1 and 2 as a key component to explain for anti-cancer activity of Alnus species., (© 2014 Wiley Periodicals, Inc.)

Licorice is a traditional botanical medicine, and has historically been commonly prescribed in Asia to treat various diseases. Glycyrrhizin (Gc), a triterpene compound, is the most abundant phytochemical constituent of licorice. However, high intake or long-term consumption of Gc has been associated with a number of side effects, including hypertension. However, the presence of alternative bioactive compounds in licorice with anti-carcinogenic effects has long been suspected. Licochalcone A (LicoA) is a prominent member of the chalcone family and can be isolated from licorice root. To date, there have been no reported studies on the suppressive effect of LicoA against solar ultraviolet (sUV)-induced cyclooxygenase (COX)-2 expression and the potential molecular mechanisms involved. Here, we show that LicoA, a major chalcone compound of licorice, effectively inhibits sUV-induced COX-2 expression and prostaglandin E2 PGE2 generation through the inhibition of activator protein 1 AP-1 transcriptional activity, with an effect that is notably more potent than Gc. Western blotting analysis shows that LicoA suppresses sUV-induced phosphorylation of Akt/ mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinases (ERK)1/2/p90 ribosomal protein S6 kinase (RSK) in HaCaT cells. Moreover, LicoA directly suppresses the activity of phosphoinositide 3-kinase (PI3K), mitogen-activated protein kinase kinase (MEK)1, and B-Raf, but not Raf-1 in cell-free assays, indicating that PI3K, MEK1, and B-Raf are direct molecular targets of LicoA. We also found that LicoA binds to PI3K and B-Raf in an ATP-competitive manner, although LicoA does not appear to compete with ATP for binding with MEK1. Collectively, these results provide insight into the biological action of LicoA, which may have potential for development as a skin cancer chemopreventive agent.

Studies have shown that a major metabolite of the red ginseng ginsenoside Rb1, called 20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol (GPD), exhibits anticancer properties. However, the chemotherapeutic effects and molecular mechanisms behind GPD action in human melanoma have not been previously investigated. Here we report the anticancer activity of GPD and its mechanism of action in melanoma cells. GPD, but not its parent compound Rb1, inhibited melanoma cell proliferation in a dose-dependent manner. Further investigation revealed that GPD treatment achieved this inhibition through the induction of autophagy and apoptosis, while Rb1 failed to show significant effect at the same concentrations. The inhibitory effect of GPD appears to be mediated through the induction of AMPK and the subsequent attenuation of mTOR phosphorylation. In addition, GPD activated c-Jun by inducing JNK phosphorylation. Our findings suggest that GPD suppresses melanoma growth by inducing autophagic cell death and apoptosis via AMPK/JNK pathway activation. GPD therefore has the potential to be developed as a chemotherapeutic agent for the treatment of human melanoma.

Phthalates are used in industry products, household items, and medical tools as plasticizers. Human exposure to phthalates has raised concern about its toxicity. In the present study, optimization was conducted for the simultaneous analysis of eight kinds of phthalate metabolites using gas chromatography-mass spectrometry (GC-MS): MEP, MiBP, MnBP, MBzP, MiNP, MEHP, MEOHP, and MEHHP. In order to minimize the matrix effect and to do quantitative analysis, isotope dilution and LLE-GC-MS methods were performed. Urine samples were enzymatically hydrolyzed, extracted with a mixture of n-hexane and ethyl ether (8:2; v:v), and subsequently derivatized with trimethylsilylation. All eight kinds of analytes showed clear resolution and high reproducibility in GC-MS results. The method detection limit ranged from 0.05 ng/mL to 0.2 ng/mL. Calibration curves were found to be linear from 0.2 to 100 ng/mL with -(2)>0.992. The relative standard deviation of the intraday precision using water and urine ranged from 2.1% to 16.3%. The analysis was performed with urine samples that were collected from adults residing in the Republic of Korea. The analyzed concentration results were compared according to gender and region. As a result, DEHP metabolites showed the highest detected concentration (75.92 μg/g creatinine, 100%), and MiNP, a metabolite of DiNP, showed the lowest detected concentration (0.42 μg/g creatinine, 22.5%). On average, female urine (200.76 μg/g creatinine) had a higher detected concentration of ∑8 phthalate metabolites than male urine. Samples from rural regions (211.96 μg/g creatinine) had higher levels than samples from urban regions., (© 2013.)

Quercetin is a major flavonoid compound found in red wine at a much higher concentration than the phytoalexin resveratrol. In this study, we examined potential anti-metastatic effects and found that compared to resveratrol, quercetin more potently inhibits H-Ras-induced invasion and migration in MCF10A human epithelial cells, an effect likely mediated by the mitigation of matrix metalloproteinase (MMP)-2 activation. We then measured Akt phosphorylation to investigate whether the decreased MMP-2 activation was attributable to the inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt signalling. Quercetin, but not resveratrol at equivalent concentrations, suppressed the phosphorylation of Akt and was a more potent inhibitor of PI3K activity than resveratrol. An ex vivo binding assay further revealed that quercetin directly binds to PI3K. Collectively, these results suggest that PI3K is a molecular target of quercetin for the inhibition of H-Ras-induced invasion and migration of MCF10A cells., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The c-Jun N-terminal kinases (JNK) play an important role in many physiologic processes induced by numerous stress signals. Each JNK protein appears to have a distinct function in cancer, diabetes, or Parkinson's disease. Herein, we found that licochalcone A, a major phenolic constituent isolated from licorice root, suppressed JNK1 activity but had little effect on JNK2 in vitro activity. Although licochalcone A binds with JIP1 competitively with either JNK1 or JNK2, a computer simulation model showed that after licochalcone A binding, the ATP-binding cleft of JNK1 was distorted more substantially than that of JNK2. This could reduce the affinity of JNK1 more than JNK2 for ATP binding. Furthermore, licochalcone A inhibited JNK1-mediated, but not JNK2-mediated, c-Jun phosphorylation in both ex vivo and in vitro systems. We also observed that in colon and pancreatic cancer cell lines, JNK1 is highly expressed compared with normal cell lines. In cancer cell lines, treatment with licochalcone A or knocking down JNK1 expression suppressed colon and pancreatic cancer cell proliferation and colony formation. The inhibition resulted in G1 phase arrest and apoptosis. Moreover, an in vivo xenograft mouse study showed that licochalcone A treatment effectively suppressed the growth of HCT116 xenografts, without affecting the body weight of mice. These results show that licochalcone A is a selective JNK1 inhibitor. Therefore, we suggest that because of the critical role of JNK1 in colon cancer and pancreatic carcinogenesis, licochalcone A might have preventive or therapeutic potential against these devastating diseases., (©2013 AACR.)

Licorice root is known to possess various bioactivities, including anti-inflammatory and anticancer effects. Glycyrrhizin, a triterpene compound, is the most abundant constituent of dried licorice root. However, high intake or long-term consumption of glycyrrhizin causes several side effects, such as hypertension, hypertensive encephalopathy, and hypokalemia. Therefore, finding additional active compounds other than glycyrrhizin in licorice that exhibit anticancer effects is worthwhile. We found that isoangustone A (IAA), a novel flavonoid from licorice root, suppressed proliferation of human melanoma cells. IAA significantly blocked cell-cycle progression at the G1-phase and inhibited the expression of G1-phase regulatory proteins, including cyclins D1 and E in the SK-MEL-28 human melanoma cell line. IAA suppressed the phosphorylation of Akt, GSK-3β, and JNK1/2. IAA also bound to phosphoinositide 3-kinase (PI3K), MKK4, and MKK7, strongly inhibiting their kinase activities in an ATP-competitive manner. Moreover, in a xenograft mouse model, IAA significantly decreased tumor growth, volume, and weight of SK-MEL-28 xenografts. Collectively, these results suggest that PI3K, MKK4, and MKK7 are the primary molecular targets of IAA in the suppression of cell proliferation. This insight into the biologic actions of IAA provides a molecular basis for the potential development of a new chemotherapeutic agent.

Metastasis is one of the most threatening features of the oncogenic process and the main cause of cancer-related mortality. Several studies have demonstrated that matrix metalloproteinases (MMPs) are critical for tumor invasion and metastasis. Resveratrol (3,5,4'-trihydroxystilbene), a phenolic compound of red wine, has been reported to be a natural chemopreventive agent. However, the cancer preventive effects of piceatannol (3,5,3',4'-tetrahydroxystilbene), a metabolite of resveratrol and the underlying molecular mechanisms have not yet been fully elucidated. In this study, we report that piceatannol inhi-bits H-ras-induced MMP-2 activity and the invasive phenotype of MCF10A human breast epithelial cells harboring mutated H-ras (H-ras MCF10A cells) more effectively than resveratrol. Piceatannol attenuated the H-ras-induced phosphorylation of Akt in a time- and dose-dependent manner, whereas resveratrol, at the same concentrations, did not exert an inhibitory effect. In vitro kinase assays demonstrated that piceatannol significantly inhibited phosphatidylinositol 3-kinase (PI3K) activity and suppressed phospha-tidylinositol (3,4,5)-trisphosphate (PIP3) expression in the H-ras MCF10A cells. Ex vivo pull-down assays revealed that piceatannol directly bound to PI3K, inhibiting PI3K activity. Data from molecular docking suggested that piceatannol is a more tight-binding inhibitor than resveratrol due to the additional hydrogen bond between the hydroxyl group and the backbone amide group of Val882 in the ATP-binding pocket of PI3K.

Persistent organochlorine pesticides (OCPs) are well known to accumulate in environment and to instigate disruptions in endocrine system. In the present study, 18 kinds of OCPs were bio-monitored from 1904 adult serums. Analysis was performed with headspace gas chromatography (HS-GC) which has the advantage to require small volume of serum (1mL) without complex pretreatment and (13)C isotope labeled internal standard mix was used for quantitation. As a result, eleven out of 18 OCPs, including hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethane metabolites (DDTs) were detected. HCB was the most frequently detected OCP (8.0%) with an average concentration of 1.74ngg(-1) lipid (2.10ngg(-1) lipid-99.80ngg(-1) lipid). p,p'-Dichlorodiphenyldichloroethylene (p,p'-DDE) had the highest average concentration of 21.65ngg(-1) lipid (12.80ngg(-1) lipid-2270ngg(-1) lipid) and was detected from 7.5% of serum samples. The average concentration of ∑DDT metabolites was 32.04ngg(-1) lipid (6.61ngg(-1) lipid-2800ngg(-1) lipid) with detection frequency of 9.0%. Results interpreted with respect to age groups showed increase in ∑OCPs and ∑DDTs concentrations as age increases, except for the 20. Results interpreted with respect to gender, in general, illustrated higher detected concentration of OCPs in male serums than in female serums; however, the result trend was reversed in age group of the sixties. The above results will be applicable to health impact assessment of Koreans in relation to environmental contaminations., (Published by Elsevier Ltd.)

Di(2-ethylhexyl) phthalate (DEHP) is one of the common phthalate plasticizers used primarily in soft polyvinyl chloride, which is a plastic polymer that makes up the total weight of goods from 1% up to 40% in many consumer products. The aims of this study were to examine the urinary DEHP metabolites in South Korean children and to investigate the correlation between mother and child DEHP urine excretion. Three kinds of urinary DEHP metabolites: mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (5-OH-MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (5-oxo-MEHP), were analyzed. The total of 954 samples (nChildren=392, nMothers=265, nAadults=297), including 258 mother and child pairs, were analyzed using isotope dilution gas chromatography-mass spectrometry. Many studies present higher concentration of DEHP metabolites detected from adults in reproductive age than adults in other ages. Therefore, adults who are age-matched to mothers were evaluated to serve as a standard of comparison against mothers. All statistical analysis was made by adjusting detected volume concentrations (μg/L) with respect to creatinine concentrations (mg/dL) since urinary DEHP metabolites were studied using human reference. The difference in median levels of sum of urinary DEHP metabolites was only significant when children were analyzed in relation to region (p-value≤0.005). Among the three DEHP metabolites, only MEHP of children was significantly correlated to that of paired mothers (p-value≤0.01). The present paper defines the relative metabolic rate (RMR) of DEHP metabolism for the first time in study on phthalates. Children had faster RMR than mothers and adults, specifically in the first step of DEHP metabolism (RMR1: MEHP hydroxylation to 5-OH-MEHP), and RMR1 of children between 1 and 24 months was the fastest. The above results may be used to study and assess human health risk from DEHP exposures, especially among mothers and children in Korea., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

c-Jun NH2-terminal kinases (JNKs) and phosphatidylinositol 3-kinase (PI3-K) play critical roles in chronic diseases such as cancer, type II diabetes, and obesity. We describe here the binding of quercetagetin (3,3',4',5,6,7-hydroxyflavone), related flavonoids, and SP600125 to JNK1 and PI3-K by ATP-competitive and immobilized metal ion affinity-based fluorescence polarization assays and measure the effect of quercetagetin on JNK1 and PI3-K activities. Quercetagetin attenuated the phosphorylation of c-Jun and AKT, suppressed AP-1 and NF-κB promoter activities, and also reduced cell transformation. It attenuated tumor incidence and reduced tumor volumes in a two-stage skin carcinogenesis mouse model. Our crystallographic structure determination data show that quercetagetin binds to the ATP-binding site of JNK1. Notably, the interaction between Lys55, Asp169, and Glu73 of JNK1 and the catechol moiety of quercetagetin reorients the N-terminal lobe of JNK1, thereby improving compatibility of the ligand with its binding site. The results of a theoretical docking study suggest a binding mode of PI3-K with the hydroxyl groups of the catechol moiety forming hydrogen bonds with the side chains of Asp964 and Asp841 in the p110γ catalytic subunit. These interactions could contribute to the high inhibitory activity of quercetagetin against PI3-K. Our study suggests the potential use of quercetagetin in the prevention or therapy of cancer and other chronic diseases., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A new sensor for the fluorescent and colorimetric detection of CO(2) is described. The system utilizes fluoride to activate a tetrapropyl benzobisimidazolium salt and operates in the absence of an exogenous base. On the basis of spectroscopic and theoretical analyses, the mode of action of the present system is ascribed to the fluoride-induced formation of an N-heterocyclic carbene intermediate that reacts with CO(2) to form an imidazolium carboxylate.

Naphthoimidazolium groups can form unique ionic hydrogen bonds with anions as imidazolium moieties, and in addition, they are fluorescent, so no further elaborative synthesis is needed to introduce a fluorescent group. In this paper, three naphthoimidazolium derivatives were synthesized and studied for the recognition of nucleotides. Compound 1 composed of a single naphthoimidazolium group and quaternary ammonium group did not show any significant fluorescent changes with various anions and nucleotides, such as ATP, GTP, CTP, TTP, UTP, ADP and AMP. A tripodal compound 3 bearing three naphthoimidazolium groups and three quaternary ammonium groups, respectively, showed large fluorescence enhancements with UTP, CTP and TTP and moderate fluorescence enhancements with ATP and pyrophosphate and a fluorescence quenching effect with GTP. On the other hand, compound 2 bearing two naphthoimidazolium groups and two quaternary ammonium groups displayed a selective fluorescence enhancement with ATP and a selective fluorescence quenching effect with GTP in 100% aqueous solution.

Indole-3-carbinol (I3C) is produced in Brassica vegetables such as broccoli and cabbage and has been shown to inhibit proliferation and induce apoptosis in various cancer cells, including breast, prostate, colon, and leukemia. However, only high doses of I3C were shown to inhibit cell proliferation (IC(50) = 200-300 μmol/L). Our goal here was to develop a more potent antitumor agent by modifying the structure of I3C. We created I3C derivatives and found that (3-chloroacetyl)-indole (3CAI) more strongly inhibited colon cancer cell growth than I3C. In addition, by screening 85 kinases in a competitive kinase assay, we found that 3CAI was a specific AKT inhibitor. AKT is a serine/threonine kinase that plays a pivotal role in promoting transformation and chemoresistance by inducing proliferation and inhibiting apoptosis. Therefore, AKT is regarded as a critical target for cancer therapy. 3ICA, a derivative of I3C, is a potent and specific AKT inhibitor. This compound showed significant inhibition of AKT in an in vitro kinase assay and suppressed expression of AKT direct downstream targets such as mTOR and GSK3β as well as induced growth inhibition and apoptosis in colon cancer cells. In addition, oral administration of this potent AKT inhibitor suppressed cancer cell growth in an in vivo xenograft mouse model.

Benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE) is a well-known carcinogen that is associated with skin cancer. Abnormal expression of cyclooxygenase-2 (COX-2) is an important mediator in inflammation and tumor promotion. We investigated the inhibitory effect of cyanidin-3-glucoside (C3G), an anthocyanin present in fruits, on B[a]PDE-induced COX-2 expression in mouse epidermal JB6 P+ cells. Pretreatment with C3G resulted in the reduction of B[a]PDE-induced expression of COX-2 and COX-2 promoter activity. The activation of activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) induced by B[a]PDE was also attenuated by C3G. C3G attenuated the B[a]PDE-induced phosphorylation of MEK, MKK4, Akt, and mitogen-activated protein kinases (MAPKs), but no effect on the phosphorylation of the upstream MAPK regulator Fyn. However, kinase assays demonstrated that C3G suppressed Fyn kinase activity and C3G directly binds Fyn kinase noncompetitively with ATP. By using PP2, a pharmacological inhibitor for SFKs, we showed that Fyn kinase regulates B[a]PDE-induced COX-2 expression by activating MAPKs, AP-1 and NF-κB. These results suggest that C3G suppresses B[a]PDE-induced COX-2 expression mainly by blocking the activation of the Fyn signaling pathway, which may contribute to its chemopreventive potential., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Epidemiologic and animal studies revealed that capsaicin can act as a carcinogen or cocarcinogen. However, the molecular mechanisms of the cancer-promoting effects of capsaicin are not clear. Here, we report that capsaicin has a cocarcinogenic effect on 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin carcinogenesis in vivo and is mediated through the epidermal growth factor receptor (EGFR), but not the transient receptor potential vanilloid subfamily member 1 (TRPV1). Topical application of capsaicin on the dorsal skin of 7,12-dimetylbenz(a)anthracene-initiated and TPA-promoted TRPV1 wild-type (WT) and TRPV1 knockout (KO) mice induced more and larger skin tumors in TRPV1/KO mice, suggesting a TRPV1-independent mechanism. Cyclooxygenase-2 (COX-2) was highly elevated by capsaicin treatment in tumors and murine embryonic fibroblasts from TRPV1/KO mice. Inhibitors of EGFR/MEK signaling suppressed TPA/capsaicin-induced COX-2 expression in TRPV1/KO cells, indicating that activation of EGFR and its downstream signaling is involved in COX-2 elevation. Capsaicin induced a further induction of TPA-increased COX-2 expression in EGFR/WT cells, but not in EGFR/KO cells. TPA/capsaicin cotreatment caused EGFR tyrosine phosphorylation and activated EGFR downstream signaling, including ERKs and Akt in EGFR/WT, but not EGFR/KO cells. Specific inhibition of EGFR and TRPV1 indicated that capsaicin-induced ERK activation in A431 cells was dependent on EGFR, but not TRPV1. Together, these findings suggest that capsaicin might act as a cocarcinogen in TPA-induced skin carcinogenesis through EGFR-dependent mechanisms.

Numerous in vitro and in vivo studies have shown that isoflavones exhibit anti-proliferative activity against epidermal growth factor (EGF) receptor-positive malignancies of the breast, colon, skin, and prostate. 7,3',4'-Trihydroxyisoflavone (7,3',4'-THIF) is one of the metabolites of daidzein, a well known soy isoflavone, but its chemopreventive activity and the underlying molecular mechanisms are poorly understood. In this study, 7,3',4'-THIF prevented EGF-induced neoplastic transformation and proliferation of JB6 P+ mouse epidermal cells. It significantly blocked cell cycle progression of EGF-stimulated cells at the G(1) phase. As shown by Western blot, 7,3',4'-THIF suppressed the phosphorylation of retinoblastoma protein at Ser-795 and Ser-807/Ser-811, which are the specific sites of phosphorylation by cyclin-dependent kinase (CDK) 4. It also inhibited the expression of G(1) phase-regulatory proteins, including cyclin D1, CDK4, cyclin E, and CDK2. In addition to regulating the expression of cell cycle-regulatory proteins, 7,3',4'-THIF bound to CDK4 and CDK2 and strongly inhibited their kinase activities. It also bound to phosphatidylinositol 3-kinase (PI3K), strongly inhibiting its kinase activity and thereby suppressing the Akt/GSK-3beta/AP-1 pathway and subsequently attenuating the expression of cyclin D1. Collectively, these results suggest that CDKs and PI3K are the primary molecular targets of 7,3',4'-THIF in the suppression of EGF-induced cell proliferation. These insights into the biological actions of 7,3',4'-THIF provide a molecular basis for the possible development of new chemoprotective agents.

Aims: Abnormal migration and proliferation of human aortic smooth muscle cells (HASMCs) to the intima causes intimal thickening of the aorta, which is strongly related to the development of atherosclerosis. Previous studies have suggested that red wine polyphenols, particularly resveratrol, have great protective effects against cardiovascular diseases. Here, we compared the anti-atherosclerotic effect of piceatannol, a metabolite of resveratrol, and its underlying mechanisms., Methods and Results: We demonstrated that piceatannol inhibited platelet-derived growth factor (PDGF)-BB-induced cell migration using a modified Boyden chamber assay and wound healing assay. Western blot analysis showed that PDGF-BB-induced phosphorylation of Akt, p70S6K, and p38 was inhibited by piceatannol, but not resveratrol. In vitro and ex vivo phosphoinositide 3-kinase (PI3K) assays demonstrated that piceatannol suppressed PI3K activity more effectively than resveratrol. PDGF-BB-induced migration and proliferation of HASMCs were inhibited by treatment with a commercial PI3K inhibitor, LY294002. Both in vitro and ex vivo pull-down assays revealed that piceatannol directly binds with sepharose 4B-PI3K beads in an ATP-competitive manner., Conclusion: The results of the present study demonstrate that piceatannol directly binds with PI3K in an ATP-competitive manner and suppresses PI3K activity with anti-atherosclerotic effects.

Matrix metalloproteinases (MMPs) are involved in various skin disorders, including photoaging, dermatitis, and tumorigenesis. Tumor necrosis factor (TNF)-alpha is a key proinflammatory cytokine that acts to provoke inflammation, proliferation, and tumorigenesis. The present study investigated the possible inhibitory effects of red wine polyphenols on TNF-alpha-induced upregulation of MMP-9 and on the migratory phenotype of JB6 P+ mouse epidermal (JB6 P+) cells. Red wine extract (RWE) and quercetin, which is a major flavonoid present in red wine, inhibited significantly the TNF-alpha-induced upregulation of MMP-9 and cell migration, whereas resveratrol did not have significant inhibitory effects. The inhibitory effects of RWE and quercetin were mediated by suppression of the phosphorylation of Akt and the transactivation of activator protein-1 and nuclear factor-kappaB, as determined by Western blotting and luciferase assays, respectively. Aside from Akt, quercetin had no effect on the phosphorylation of other mitogen-activated protein kinases. Direct kinase assay data revealed that RWE and quercetin inhibited phosphatidylinositol 3-kinase (PI3K) activity. The results of direct and cell-based pull-down assays demonstrated that RWE and quercetin bound to PI3K, resulting in the inhibition of PI3K activity. Using chemical inhibitors, it was confirmed that the PI3K-dependent Akt pathway was involved in TNF-alpha-induced MMP-9 upregulation and migration in JB6 P+ cells. Collectively, these results indicate that TNF-alpha-induced MMP-9 upregulation and the migratory phenotype are associated with the PI3K/Akt pathway, and that these effects are inhibited strongly by RWE and quercetin.

We identified the promoter region of the human GD3 synthase (hST8Sia I) gene to elucidate the mechanism underlying the regulation of hST8Sia I expression in human glioblastoma cells. The 5'-rapid amplification of cDNA end using mRNA prepared from U-87MG cells revealed the presence of transcription start site of hST8Sia I gene, and the 5'-terminal analysis of its product showed that transcription started from 648 nucleotides upstream of the translational initiation site. Functional analysis of the 5'-flanking region of the hST8Sia I gene by transient expression method revealed that the region from -638 to -498 is important for transcriptional activity of the hST8Sia I gene in U-87MG and T98G cells. This region lacks apparent TATA and CAAT boxes, but contains putative binding sites for transcription factors AREB6 and Elk-1. Site-directed mutagenesis and transient transfection assays demonstrated that both AREB6 and Elk-1 elements in this region were required for the promoter activity in U-87MG and T98G cells. These results indicated that both AREB6 and Elk-1 might play an essential role in the transcriptional activity of hST8Sia I gene essential for GD3 synthesis in human glioblastoma cells.

In this study, we have shown the transcriptional regulation of the human GD3 synthase (hST8Sia I) induced by valproic acid (VPA) in human neuroblastoma SK-N-BE(2)-C cells. To elucidate the mechanism underlying the regulation of hST8Sia I gene expression in VPA-stimulated SK-N-BE(2)-C cells, we characterized the promoter region of the hST8Sia I gene. Functional analysis of the 5'-flanking region of the hST8Sia I gene by the transient expression method showed that the -1146 to -646 region, which contains putative binding sites for transcription factors c-Ets-1, CREB, AP-1 and NF-kappaB, functions as the VPA-inducible promoter of hST8Sia I in SK-N-BE(2)-C cells. Site-directed mutagenesis and electrophoretic mobility shift assay indicated that the NF-kappaB binding site at -731 to -722 was crucial for the VPA-induced expression of hST8Sia I in SK-N-BE(2)-C cells. In addition, the transcriptional activity of hST8Sia I induced by VPA in SK-N-BE(2)-C cells was strongly inhibited by SP600125, which is a c-Jun N-terminal kinase (JNK) inhibitor, and GO6976, which is a protein kinase C (PKC) inhibitor, as determined by RT-PCR (reverse transcription-polymerase chain reaction) and luciferase assays. These results suggest that VPA markedly modulated transcriptional regulation of hST8Sia I gene expression through PKC/JNK signal pathways in SK-N-BE(2)-C cells.